WO2024212369A1

WO2024212369A1 - Satellite signal capture method and device

Info

Publication number: WO2024212369A1
Application number: PCT/CN2023/104919
Authority: WO
Inventors: 张瑜; 王名为; 卢家林; 伍景成
Original assignee: 泰斗微电子科技有限公司
Priority date: 2023-04-10
Filing date: 2023-06-30
Publication date: 2024-10-17
Also published as: CN116520360A

Abstract

The present application discloses a satellite signal capture method and device. The method can be applied to a receiver, and the method comprises: acquiring a plurality of Doppler shifts corresponding to a plurality of satellite signals emitted by a target satellite, wherein the plurality of satellite signals are in one-to-one correspondence with the plurality of Doppler shifts, and each Doppler shift represents, when the receiver receives an input signal, a shift of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler shift; determining a Doppler shift search range according to the plurality of Doppler shifts; and according to a pseudo-random code and the Doppler shift search range, searching for a satellite signal to be captured emitted by the target satellite, so as to capture the satellite signal to be captured. The method can improve the efficiency of capturing satellite signals.

Description

Satellite signal acquisition method and device

This application claims priority to the Chinese patent application filed with the China Patent Office on April 10, 2023, with application number 202310383737.5 and invention name “Satellite Signal Capture Method and Device”, the entire contents of which are incorporated by reference into this application.

Technical Field

The present application relates to the technical field of satellite signal processing, and in particular to a satellite signal capture method and device.

Background Art

The capture of Global Navigation Satellite System (GNSS) signals is the basis for signal tracking and navigation information resolution in satellite navigation and positioning. The purpose of satellite signal capture is to obtain the carrier frequency and pseudo-random code phase (also known as pseudo-code phase) of the satellite signal, so as to enter the tracking state after capture and ensure the reception and demodulation of satellite signals. When capturing GNSS signals, when the relative speed between the receiver and the satellite is zero, the carrier frequency is the intermediate frequency after the satellite signal carrier frequency is down-converted. However, in actual applications, due to the change in the satellite's time, the relative speed between the receiver and the satellite is not equal to zero. Due to the relative speed between the receiver and the satellite, the frequency of the satellite signal received by the receiver is offset to a certain extent, that is, the Doppler frequency shift, which affects the receiver's acquisition of the carrier frequency. Therefore, in this case, if the receiver wants to obtain the carrier frequency, it must complete the frequency search process according to the size of the Doppler frequency shift.

Technical issues

In the traditional satellite signal acquisition process, it is usually necessary to traverse a larger range of Doppler frequency shifts, which makes it take a long time for the receiver to acquire the satellite signal, resulting in low efficiency in acquiring the satellite signal.

Therefore, a method is urgently needed that can improve the efficiency of capturing satellite signals.

Technical Solutions

The present application provides a satellite signal capture method and device, which can improve the efficiency of capturing satellite signals.

To solve the above problems, in a first aspect, an embodiment of the present application provides a satellite signal capture method, the method comprising: obtaining multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by a target satellite, wherein the multiple satellite signals and the multiple Doppler frequency shifts correspond one to one; each Doppler frequency shift represents an offset of the frequency of an input signal relative to the frequency of a satellite signal corresponding to each Doppler frequency shift when a receiver receives the input signal; determining a Doppler frequency shift search range based on the multiple Doppler frequency shifts; and searching for a satellite signal to be captured transmitted by the target satellite based on a pseudo-random code and the Doppler frequency shift search range to capture the satellite signal to be captured.

In one possible design, determining a Doppler frequency shift search range based on the multiple Doppler frequency shifts includes: determining a maximum Doppler frequency shift among the multiple Doppler frequency shifts as a maximum search value of the search range, and determining a minimum Doppler frequency shift among the multiple Doppler frequency shifts as a minimum search value of the search range.

Optionally, in a possible design, determining a Doppler frequency shift search range according to the multiple Doppler frequency shifts includes: determining a mean square error of the multiple Doppler frequency shifts according to the multiple Doppler frequency shifts; determining the Doppler frequency shift search range according to the mean square error, wherein a maximum Doppler frequency shift included in the search range is a product of a preset threshold and the mean square error, and the search range includes The minimum Doppler shift is the inverse of the maximum Doppler shift.

Optionally, in a possible design, searching for a satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range to capture the satellite signal to be captured includes: determining a plurality of Doppler frequency shifts to be searched according to a preset frequency step value and the Doppler frequency shift search range; mixing the acquired input signal to be analyzed and the local carrier signal to obtain an I-channel baseband signal and a Q-channel baseband signal, wherein the frequency of the local carrier signal is the same as the searched Doppler frequency shift, and the plurality of Doppler frequency shifts to be searched include the searched Doppler frequency shift; The input signal to be analyzed is a digital intermediate frequency signal obtained after the satellite signal to be captured is received by the receiver and processed by the radio frequency front-end; the I-channel baseband signal is obtained by mixing the input signal to be analyzed with the local carrier signal; the Q-channel baseband signal is obtained by mixing the input signal to be analyzed with the orthogonal signal of the local carrier signal; according to the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code, the satellite signal to be captured transmitted by the target satellite is searched to capture the satellite signal to be captured.

Optionally, in a possible design, searching for the satellite signal to be captured transmitted by the target satellite according to the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code to capture the satellite signal to be captured includes: moving the pseudo-random code sequence of the pseudo-random code by a preset number of chips in a first search Doppler frequency shift, and performing correlation operations with the I-channel baseband signal and the Q-channel baseband signal, respectively, to obtain a first correlation result of the I-channel and a second correlation result of the Q-channel, wherein the Doppler frequency shift of the first search is the Doppler frequency shift of the search; and performing correlation operations on the first correlation result and the second correlation result of the Q-channel, respectively. The first embodiment of the present invention is to perform coherent integration operation on two correlation results to obtain a first integration result of the first correlation result and a second integration result of the second correlation result; perform incoherent integration processing on the modulus value of the first integration result and the modulus value of the second integration result to obtain a first incoherent integration processing result; compare the first incoherent integration processing result with a preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the first incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the first incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.

Optionally, in a possible design, when the first non-coherent integration processing result does not exceed the preset capture threshold, and the movement in units of a preset number of code chips exceeds the code period of the pseudo-random code, the method further includes: moving the pseudo-random code sequence of the pseudo-random code in units of the preset number of code chips in the second search Doppler frequency shift, and performing correlation operations with the baseband signal of the I path and the baseband signal of the Q path, respectively, to obtain a third correlation result of the I path and a fourth correlation result of the Q path, wherein the Doppler frequency shift of the second search is the Doppler frequency shift of the search, and the Doppler frequency shift of the second search and the The Doppler frequency shifts of the first search are two different Doppler frequency shifts; the third correlation result and the fourth correlation result are integrated respectively to obtain a third integration result of the third correlation result and a fourth integration result of the fourth correlation result; the modulus value of the third integration result and the modulus value of the fourth integration result are incoherently integrated to obtain a second incoherent integration processing result; the second incoherent integration processing result is compared with the preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the second incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if If the second incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.

Optionally, in one possible design, the multiple Doppler shifts to be searched include a target Doppler shift, and after searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler shift search range to capture the satellite signal to be captured, the method further includes: in a case where the satellite signal to be captured is successfully captured according to the target Doppler shift and the pseudo-random code sequence of the pseudo-random code, if the search range does not include the target Doppler shift, performing the following operations: if the target Doppler shift is greater than the maximum Doppler shift included in the search range, updating the maximum Doppler shift included in the search range to the target Doppler shift; or, if the target Doppler shift is greater than the minimum Doppler shift included in the search range, updating the minimum Doppler shift included in the search range to the target Doppler shift.

Optionally, in a possible design, the multiple Doppler frequency shifts are stored in a storage space of the receiver, and acquiring the multiple Doppler frequency shifts corresponding to the multiple satellite signals transmitted by the target satellite includes: reading the multiple Doppler frequency shifts from the storage space.

In a second aspect, the present application also provides a satellite signal capture device, the device comprising: an acquisition module for acquiring multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by a target satellite, wherein the multiple satellite signals and the multiple Doppler frequency shifts correspond one to one; each Doppler frequency shift represents an offset of the frequency of an input signal relative to the frequency of a satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal; a determination module for determining a Doppler frequency shift search range based on the multiple Doppler frequency shifts; a search module for searching for a satellite signal to be captured transmitted by the target satellite based on a pseudo-random code and the Doppler frequency shift search range, so as to capture the satellite signal to be captured.

In one possible design, the determination module is further used to: determine a maximum Doppler frequency shift among the multiple Doppler frequency shifts as a maximum search value of the search range, and determine a minimum Doppler frequency shift among the multiple Doppler frequency shifts as a minimum search value of the search range.

Optionally, in another possible design, the determination module is further used to: determine the mean square error of the multiple Doppler frequency shifts based on the multiple Doppler frequency shifts; determine the Doppler frequency shift search range based on the mean square error, wherein the maximum Doppler frequency shift included in the search range is the product of a preset threshold and the mean square error, and the minimum Doppler frequency shift included in the search range is the inverse of the maximum Doppler frequency shift.

Optionally, in another possible design, the search module is also used to: determine multiple Doppler frequency shifts to be searched according to a preset frequency step value and the Doppler frequency shift search range; mix the acquired input signal to be analyzed and the local carrier signal to obtain an I-channel baseband signal and a Q-channel baseband signal, wherein the frequency of the local carrier signal is the same as the searched Doppler frequency shift, and the multiple Doppler frequency shifts to be searched include the searched Doppler frequency shift; the input signal to be analyzed is a digital intermediate frequency signal obtained after the satellite signal to be captured received by the receiver is processed by the RF front end; the I-channel baseband signal is obtained by mixing the input signal to be analyzed with the local carrier signal; the Q-channel baseband signal is obtained by mixing the input signal to be analyzed with the orthogonal signal of the local carrier signal; and according to the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code, the satellite signal to be captured transmitted by the target satellite is searched to capture the satellite signal to be captured.

Optionally, in another possible design, the search module is further used to: move the pseudo-random code sequence of the pseudo-random code in units of a preset number of chips in the Doppler frequency shift of the first search, and perform correlation operations with the baseband signal of the I channel and the baseband signal of the Q channel respectively to obtain a first correlation result of the I channel and a second correlation result of the Q channel, wherein the Doppler frequency shift of the first search is the Doppler frequency shift of the search; perform coherent integration operations on the first correlation result and the second correlation result respectively to obtain a first integration result of the first correlation result and a second integration result of the second correlation result; perform incoherent integration processing on the modulus value of the first integration result and the modulus value of the second integration result to obtain a first incoherent integration processing result; compare the first incoherent integration processing result with a preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the first incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the first incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.

Optionally, in another possible design, when the first incoherent integration processing result does not exceed the preset capture threshold, and the movement in units of a preset number of code chips exceeds the code period of the pseudo-random code, the search module is further used to: move the pseudo-random code sequence of the pseudo-random code in units of the preset number of code chips in the second search Doppler frequency shift, and perform correlation operations with the baseband signal of the I channel and the baseband signal of the Q channel respectively to obtain a third correlation result of the I channel and a fourth correlation result of the Q channel, wherein the Doppler frequency shift of the second search is the Doppler frequency shift of the search, and the Doppler frequency shift of the second search and the Doppler frequency shift of the first search are two different Doppler frequencies. shift; respectively perform integration operations on the third correlation result and the fourth correlation result to obtain a third integration result of the third correlation result and a fourth integration result of the fourth correlation result; perform incoherent integration processing on the modulus value of the third integration result and the modulus value of the fourth integration result to obtain a second incoherent integration processing result; compare the second incoherent integration processing result with the preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the second incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the second incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.

Optionally, in another possible design, the device also includes an updating module, the multiple Doppler shifts to be searched include a target Doppler shift, and after searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler shift search range to capture the satellite signal to be captured, the updating module is used to: in a case where the satellite signal to be captured is successfully captured according to the target Doppler shift and the pseudo-random code sequence of the pseudo-random code, if the search range does not include the target Doppler shift, perform the following operations: if the target Doppler shift is greater than the maximum Doppler shift included in the search range, update the maximum Doppler shift included in the search range to the target Doppler shift; or, if the target Doppler shift is greater than the minimum Doppler shift included in the search range, update the minimum Doppler shift included in the search range to the target Doppler shift.

Optionally, in another possible design, the multiple Doppler frequency shifts are stored in a storage space of the receiver, and the acquisition module is further used to: read the multiple Doppler frequency shifts from the storage space.

In a third aspect, the present application also provides a satellite information acquisition device, comprising at least one processor, wherein the at least one processor is used to couple with a memory, read and execute instructions in the memory, so as to implement the satellite information acquisition device provided in any possible design of the first aspect. method.

Optionally, the satellite information acquisition device also includes the memory.

In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is run on a computer, the computer executes the method provided in any possible design of the first aspect described above.

In a fifth aspect, the present application also provides a chip system, including a processor, for calling and running a computer program from a memory, so that a device equipped with the chip system executes the method provided in any possible design of the aforementioned first aspect.

In a sixth aspect, an embodiment of the present application further provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute a method provided in any possible design of the first aspect described above.

Beneficial Effects

The satellite signal capture method provided by the embodiment of the present application includes: obtaining multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by the target satellite, wherein the multiple satellite signals correspond to the multiple Doppler frequency shifts one by one; each Doppler frequency shift represents the frequency offset of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal; determining the Doppler frequency shift search range according to the multiple Doppler frequency shifts; searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range. In practical applications, the Doppler frequency shift is only associated with the relative motion between the target satellite and the receiver, and the local oscillator frequency deviation of the receiver. Based on this, the range of the Doppler frequency shift corresponding to the target satellite is estimable. In the above-mentioned implementation method of satellite signal capture, the receiver determines the Doppler frequency shift search range used by the receiver when searching for the satellite signal transmitted by the target satellite at the current moment according to the multiple Doppler frequency shifts corresponding to the multiple satellite signals transmitted by the target satellite at the historical moment. Among them, each Doppler frequency shift represents the offset of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal. Thereafter, the receiver searches for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range. That is to say, in the above implementation, the Doppler frequency shift search range used by the receiver when capturing the satellite signal transmitted by the target satellite is associated with the Doppler frequency shift corresponding to the satellite signal historically transmitted by the target satellite. In this way, the Doppler frequency shift search range searched by the receiver can be effectively narrowed, thereby improving the efficiency of the receiver in capturing satellite signals. In summary, the satellite signal capture method provided in the embodiment of the present application can improve the efficiency of capturing satellite signals.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG. 1 is an application scenario of the satellite signal acquisition method provided in an embodiment of the present application.

FIG2 is a schematic diagram of a satellite signal acquisition method provided in an embodiment of the present application.

FIG. 3A is a schematic diagram of the implementation process of S230 described in FIG. 2 .

FIG. 3B is a two-dimensional image of the pseudo code phase and Doppler frequency shift search range involved in the satellite signal acquisition method described in FIG. 2. Schematic diagram of the coordinate system.

FIG4 is a schematic diagram of another satellite signal acquisition method provided in an embodiment of the present application.

FIG5 is a schematic diagram of the structure of a satellite signal acquisition device provided in an embodiment of the present application.

FIG6 is a schematic diagram of the structure of a satellite signal acquisition device provided in an embodiment of the present application.

FIG. 7 is a schematic diagram of the structure of a system provided in an embodiment of the present application.

Embodiments of the present invention

The technical solution in the present application will be described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

The term "include" herein indicates the presence of the described features, integral bodies, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, integral bodies, steps, operations, elements, components and/or their collections. The terms "include", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

The term "and/or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and/or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.

In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, "at least one" means one or more, and "more than one" means two or more, unless otherwise clearly and specifically defined.

First, the professional terms involved in the embodiments of the present application are introduced.

Doppler Shift

Doppler shift refers to the change in phase and frequency caused by the difference in propagation distance when a mobile station moves in a certain direction at a constant speed. This change is usually called Doppler shift. It reveals the law that the properties of waves change during movement. The difference between the transmitted and received frequencies caused by the Doppler effect is called Doppler shift. It reveals the law that the properties of waves change during movement.

Below, application scenarios applicable to the embodiments of the present application are introduced in conjunction with the accompanying drawings.

FIG1 is an application scenario applicable to the satellite signal acquisition method provided in an embodiment of the present application. Exemplarily, the application scenario shown in FIG1 includes: at least one satellite 110 and at least one receiver 120. It is understandable that FIG1 may also include a greater number of satellites and a greater number of receivers, which is not specifically limited.

Satellite 110 is used to transmit satellite signals.

The receiver 120 is used to search for satellite signals transmitted by the satellite 110 and track the searched satellite signals.

It should be understood that the application scenario shown in Figure 1 is only for illustration and does not constitute any limitation on the application scenario to which the embodiments of the present application are applicable. For example, the scenario shown in Figure 1 may also include a greater number of receivers or satellites.

Next, the satellite signal capture method provided in the embodiment of the present application is described in detail in conjunction with Figures 2 to 4.

FIG. 2 is a schematic diagram of a satellite signal acquisition method provided in an embodiment of the present application. The satellite signal acquisition method provided in an embodiment of the present application can be executed by a receiver. It is understandable that the receiver can be implemented as software, or a combination of software and hardware. In some implementations, when the receiver is implemented as software, it can be understood that the function of the receiver described in FIG. 2 can be implemented by software simulation. In other implementations, when the receiver is implemented as a combination of software and hardware, the method performed by the receiver described in FIG. 2 can be implemented by controlling the receiver by software. Exemplarily, the receiver in the embodiment of the present application can be, but is not limited to, the receiver 120 shown in FIG. 1. As shown in FIG. 2, the satellite signal acquisition method provided in an embodiment of the present application includes S210 to S230. Below, S210 to S230 are described in detail.

S210, obtaining multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by the target satellite, wherein the multiple satellite signals correspond to the multiple Doppler frequency shifts one by one; each Doppler frequency shift represents an offset of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal.

In an embodiment of the present application, the method described in S210 above may be performed by a receiver. Exemplarily, the receiver may be, but is not limited to, the receiver 120 shown in FIG. 1 . The implementation manner in which the receiver obtains multiple Doppler frequency shifts corresponding to multiple satellite signals is not specifically limited. In some implementations, multiple Doppler frequency shifts are stored in the storage space of the receiver, and the multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by the target satellite are obtained, including: reading multiple Doppler frequency shifts from the storage space. In the above implementation, the multiple Doppler frequency shifts stored in the storage space of the receiver may be determined by the receiver analyzing multiple input signals corresponding to the multiple satellite signals. Alternatively, the multiple Doppler frequency shifts stored in the storage space of the receiver may also be determined by other devices analyzing multiple input signals corresponding to the multiple satellite signals, after which the other devices send the obtained multiple Doppler frequency shifts corresponding to the target satellites to the receiver, and the receiver stores the received multiple Doppler frequency shifts in the storage space. For example, the above other devices may be, but are not limited to, other receivers other than the receiver. In an embodiment of the present application, the type of storage space of the above-mentioned receiver can be set according to the actual application scenario. In some application scenarios where power is turned on again after power failure, the storage space of the receiver described in the above implementation method may be, but is not limited to: non-volatile memory flash, or eeprom. Optionally, in other scenarios where power failure is not required, the storage space of the receiver described in the above implementation method may be, but is not limited to, RAM. In an embodiment of the present application, the number of multiple Doppler frequency shifts is not specifically limited. For example, the multiple Doppler frequency shifts may be, but are not limited to, 2, 3, 5, or 10, etc. The number of multiple Doppler frequency shifts can be determined specifically according to the actual application scenario. For example, referring to the satellite signal acquisition method described in FIG. 4 below, FIG. 4 takes i Doppler frequency shifts as an example for description, that is, the i Doppler frequency shifts described in FIG. 4 are a specific example of the above multiple Doppler frequency shifts.

S220, determining a Doppler frequency shift search range according to the multiple Doppler frequency shifts.

In the embodiment of the present application, the implementation method of determining the Doppler frequency shift search range according to multiple Doppler frequency shifts is not specifically limited. In some implementations, executing the above S220, that is, determining the Doppler frequency shift search range according to multiple Doppler frequency shifts, includes: The maximum Doppler frequency shift among the Doppler frequency shifts is determined as the maximum search value of the search range, and the minimum Doppler frequency shift among the multiple Doppler frequency shifts is determined as the minimum search value of the search range. In the above implementation, the maximum Doppler frequency shift among the multiple Doppler frequency shifts corresponding to the target satellite obtained historically is determined as the maximum search value included in the frequency search range, and the minimum Doppler frequency shift among the multiple Doppler frequency shifts corresponding to the target satellite obtained historically is determined as the minimum search value included in the frequency search range. In practical applications, the method for determining the Doppler frequency shift range described in the above implementation can be, but is not limited to, applicable to the following scenario: in this scenario, the multiple Doppler frequency shifts corresponding to the target satellite obtained by the receiver are multiple continuous values. Optionally, in some other implementations, the above S220 is performed, that is, according to the multiple Doppler shifts, the mean square error of the multiple Doppler shifts is determined; according to the mean square error, the Doppler shift search range is determined, wherein the maximum Doppler shift included in the search range is the product of a preset threshold and the mean square error, and the minimum Doppler shift included in the search range is the inverse of the maximum Doppler shift. In practical applications, the method for determining the Doppler shift range described in the above implementation may be applicable to, but not limited to, the following scenarios: in this scenario, the multiple Doppler shifts corresponding to the target satellites obtained by the receiver are multiple discrete values. Below, an example is given to describe that the maximum and minimum values of the Doppler shift search range are the product of a preset threshold and the mean square error. For example, multiple Doppler shifts are calculated, and the mean square error of the multiple Doppler shifts is obtained as σ. Therefore, the Doppler shift range can be set to [-3σ, +3σ]. It should be noted that the above two implementation methods are only illustrative and do not constitute any limitation on the “multiple Doppler frequency shifts, determining the Doppler frequency shift search range” provided in the embodiments of the present application.

S230, searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range to obtain the satellite signal to be captured.

In the embodiment of the present application, the type of pseudo-random code is not specifically limited. For example, the pseudo-random code described in S230 above may be, but is not limited to, a CA code or a P code. For example, taking the CA code as an example, for the CA code of GPS, the code step value is generally set to 1/2 chip. Since the CA code is 1023 chips long, it is considered that the code phase has 2046 values in the capture of GPS. A code period of the CA code may be 1 millisecond (ms).

Executing the above S230, that is, searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range to capture the satellite signal to be captured, includes: determining a plurality of Doppler frequency shifts to be searched according to a preset frequency step value and the Doppler frequency shift search range; mixing the acquired input signal to be analyzed and the local carrier signal to obtain an I-channel baseband signal and a Q-channel baseband signal, wherein the frequency of the local carrier signal is the same as the Doppler frequency shift to be searched, and the plurality of Doppler frequency shifts to be searched include the Doppler frequency shift to be searched. Doppler frequency shift; the input signal to be analyzed is a digital intermediate frequency signal obtained after the satellite signal to be captured is received by the receiver and processed by the RF front end; the I-channel baseband signal is obtained by mixing the input signal to be analyzed with the local carrier signal; the Q-channel baseband signal is obtained by mixing the input signal to be analyzed with the orthogonal signal of the local carrier signal; according to the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code, the satellite signal to be captured transmitted by the target satellite is searched to capture the satellite signal to be captured. The above-mentioned local carrier information can be a signal generated by the receiver, wherein the frequency of the local carrier signal is the same as the Doppler frequency shift currently being searched. Exemplarily, FIG3A shows a schematic diagram of the processing flow of the receiver described in the above implementation method processing the input signal to be analyzed to obtain the I-channel baseband signal and the Q-channel baseband signal. The size of the above-mentioned preset frequency step value is not specifically limited and can be selected according to the actual scenario. For example, the above-mentioned preset frequency step value can be but is not limited to 500Hz or 1000Hz. Exemplarily, Doppler The Doppler frequency shift search range can be [-6500Hz, +6500Hz], and the preset frequency step value can be 1000Hz. Based on this, multiple Doppler frequency shifts to be searched can include: -6500Hz, -5500Hz, -4500Hz, -3500Hz, -2500Hz, -1500Hz, -500Hz, 500Hz, 1500Hz, 2500Hz, 3500Hz, 4500Hz, 5500Hz and 6500Hz. For example, referring to the two-dimensional coordinate system shown in Fig. 3B, the abscissa of the two-dimensional coordinate system represents the Doppler frequency shift search range, wherein the Doppler frequency shift search range is [-6500Hz, +6500Hz], and the difference between any two adjacent Doppler frequency shifts is equal to the preset frequency step value. In Fig. 3B, the search unit represents (the Doppler frequency shift searched and the pseudo code phase searched). It can be understood that the process of searching for pseudo code phase and Doppler frequency shift described in the above implementation is a serial search process. Among them, the above serial search process adopts a chip priority strategy, that is, all chip positions are searched on a Doppler frequency shift, and after all chip positions are excluded, all chip positions are searched again on a new Doppler frequency shift. Optionally, the above serial search method can also be replaced by a Doppler priority strategy, specifically: at a chip position, all Doppler frequency shifts are first detected, and after all Doppler frequency shifts are excluded, the next code deviation is detected. Optionally, in other implementations, the Doppler frequency shift search range provided in the embodiment of the present application can also be applied to the parallel search process in the frequency domain. The specific implementation method of the receiver using the frequency domain parallel search method to search for the satellite signal to be captured transmitted by the target satellite according to the pseudo code phase and Doppler frequency shift search range is consistent with the frequency shift parallel search principle provided in the traditional technology, and will not be described in detail here.

Optionally, in some implementations, the above implementations describe searching for the satellite signal to be captured transmitted by the target satellite based on the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code to capture the satellite signal to be captured, including: moving the pseudo-random code sequence of the pseudo-random code by a preset number of code chips in a first search Doppler frequency shift, and performing correlation operations with the I-channel baseband signal and the Q-channel baseband signal, respectively, to obtain a first correlation result for the I-channel and a second correlation result for the Q-channel, wherein the Doppler frequency shift of the first search is the Doppler frequency shift of the search; and performing correlation operations on the first correlation result and the second correlation result of the Q-channel, respectively. The first and second correlation results are coherently integrated to obtain a first integration result of the first correlation result and a second integration result of the second correlation result; the modulus value of the first integration result and the modulus value of the second integration result are incoherently integrated to obtain a first incoherent integration processing result; the first incoherent integration processing result is compared with a preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the first incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the first incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured. Optionally, in some implementations, the following steps may also be performed: according to the first integration result, the modulus value of the first integration result is obtained; and, according to the second integration result, the modulus value of the second integration result is obtained. Exemplarily, FIG3A shows a flowchart of the above-mentioned processing of the first integration result and the second integration result to obtain the incoherent integration result. The preset number of chips described in the above implementation is not specifically limited and can be selected according to actual needs. Exemplarily, the preset number of code chips can be set as half a code chip or 1 code chip but is not limited to it. If the above implementation method determines that the first incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured has not been successfully captured. Thereafter, it is necessary to use pseudo-random codes and other Doppler frequency shifts for searching, wherein the other Doppler frequency shifts are: multiple Doppler frequency shifts to be searched include Doppler frequency shifts other than the Doppler frequency shift of the first search. Based on this, in some implementation methods, when the first incoherent integration processing result does not exceed the preset capture threshold, and the movement in units of a preset number of code chips exceeds the code period of the pseudo-random code, the method further includes: in the second search, the Doppler frequency shift moves the pseudo-random code sequence of the pseudo-random code in units of a preset number of code chips, and respectively compares it with the baseband signal of the I channel and the baseband signal of the Q channel. The third correlation result of the I channel and the fourth correlation result of the Q channel are obtained by performing correlation operation on the signals, wherein the Doppler frequency shift of the second search is the Doppler frequency shift of the search, and the Doppler frequency shift of the second search and the Doppler frequency shift of the first search are two different Doppler frequency shifts; the third correlation result and the fourth correlation result are respectively integrated to obtain a third integral result of the third correlation result and a fourth integral result of the fourth correlation result; the modulus value of the third integral result and the modulus value of the fourth integral result are incoherently integrated to obtain a second incoherent integration processing result; the second incoherent integration processing result is compared with a preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the second incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the second incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured. The Doppler frequency shift of the second search and the Doppler frequency shift of the first search are two different Doppler frequency shifts, and the Doppler frequency shift of the first search and the Doppler frequency shift of the second search are not specifically limited. For example, the Doppler frequency shift of the first search and the Doppler frequency shift of the second search can be two adjacent Doppler frequency shifts among a plurality of Doppler frequency shifts to be searched, or the Doppler frequency shift of the first search and the Doppler frequency shift of the second search can also be two non-adjacent Doppler frequency shifts among a plurality of Doppler frequency shifts to be searched. It should be noted that in actual applications, when the receiver captures the signal transmitted by the target satellite, the receiver will search for all visible satellites, wherein all visible satellites include the target satellite and satellites other than the target satellite. Among them, the pseudo-random code of each satellite is different, that is, when the pseudo-random code described in the above implementation is not a pseudo-random code associated with the target satellite, the above search process can be regarded as a three-dimensional search for pseudo-random code-frequency-phase. Optionally, when the pseudo-random code described in the above implementation is a pseudo-random code associated with the target satellite, the above search process can be regarded as a two-dimensional search for frequency-phase (ie, determined according to the pseudo-random code associated with the target satellite).

In the embodiment of the present application, the Doppler frequency shift range determined in S220 may also be updated. The updating method for updating the Doppler frequency shift range determined in S220 is not specifically limited. A method for updating the Doppler frequency shift range provided in the embodiment of the present application is described below. In some implementations, the multiple Doppler shifts to be searched include a target Doppler shift. After searching for a satellite signal to be captured transmitted by a target satellite according to a pseudo-random code and a Doppler shift search range to capture the satellite signal to be captured, the method further includes: in the case where the satellite signal to be captured is successfully captured according to the target Doppler shift and a pseudo-random code sequence of a pseudo-random code, if the search range does not include the target Doppler shift, the following operations are performed: if the target Doppler shift is greater than the maximum Doppler shift included in the search range, the maximum Doppler shift included in the search range is updated to the target Doppler shift; or, if the target Doppler shift is greater than the minimum Doppler shift included in the search range, the minimum Doppler shift included in the search range is updated to the target Doppler shift. It should be understood that the method for updating the Doppler shift range described in the above implementation is only for illustration and does not constitute any limitation. That is, other methods can also be used to update the Doppler shift search range using the target Doppler shift.

It should be understood that the method shown in FIG. 2 is for illustration only and does not constitute any limitation on the satellite signal acquisition method provided in the embodiment of the present application. For example, the pseudo-random code described in S210 may be a pseudo-random code associated with the target satellite, or, in the case where the pseudo-random code described in S210 may not be a pseudo-random code associated with the target satellite, it is still necessary to perform a step of updating the pseudo-random code to obtain the pseudo-random code described in S210.

In practical applications, the Doppler frequency shift is only related to the relative motion between the target satellite and the receiver, and the local oscillator frequency deviation of the receiver. Based on this, the range of the Doppler frequency shift corresponding to the target satellite is estimable. The multiple Doppler frequency shifts corresponding to the multiple satellite signals transmitted at the historical moment determine the Doppler frequency shift search range used by the receiver when searching for the satellite signal transmitted by the target satellite at the current moment. Wherein, each Doppler frequency shift represents the offset of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal. Thereafter, the receiver searches for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range. That is to say, in the above implementation, the Doppler frequency shift search range used by the receiver when capturing the satellite signal transmitted by the target satellite is associated with the Doppler frequency shift corresponding to the satellite signal transmitted by the target satellite in history, so that the Doppler frequency shift search range searched by the receiver can be effectively narrowed, thereby improving the efficiency of the receiver in capturing satellite signals. In addition, when the receiver successfully captures the satellite signal to be captured transmitted by the target satellite according to the Doppler frequency shift and pseudo-random code currently searched, the Doppler frequency shift search range can also be updated using the Doppler frequency shift currently searched, so as to improve the accuracy of the Doppler frequency shift search range. In summary, the satellite signal capturing method provided in the embodiments of the present application can improve the efficiency of capturing satellite signals.

Next, another satellite signal capture method provided by an embodiment of the present application is introduced in conjunction with FIG. 4 . It can be understood that the satellite signal capture method described in FIG. 4 is a specific example of the satellite signal capture method described in FIG. 2 above, and the method described in FIG. 4 is only for illustration and does not constitute any limitation to the satellite signal capture method provided by the present application. It can be understood that the receiver shown in FIG. 4 is a specific example of the receiver shown in FIG. 2 above. Specifically, the i satellite signals described in FIG. 4 are an example of the multiple satellite signals described in FIG. 2 above, the i Doppler frequency shifts described in FIG. 4 are an example of the multiple Doppler frequency shifts described in FIG. 2 above, and the input signal #1 to be analyzed described in FIG. 4 is an example of the input signal to be analyzed described in FIG. 2 above.

FIG4 is a schematic diagram of another satellite signal acquisition method provided in an embodiment of the present application. The satellite signal acquisition method provided in an embodiment of the present application can be executed by a receiver. It is understandable that the receiver can be implemented as software, or a combination of software and hardware. In some implementations, when the receiver is implemented as software, it can be understood that the function of the receiver described in FIG4 can be implemented by software simulation. In other implementations, when the receiver is implemented as a combination of software and hardware, the method performed by the receiver described in FIG4 can be implemented by controlling the receiver by software. Exemplarily, as shown in FIG4, the method includes steps S401 to S409. Below, steps S401 to S409 are described in detail.

401. The receiver obtains i Doppler frequency shifts corresponding to i satellite signals, wherein the i-th satellite signal is a digital intermediate frequency signal obtained after the i-th satellite signal transmitted by the target satellite and received by the receiver is processed by the radio frequency front end. The i satellite signals correspond to the i Doppler frequency shifts one by one, and i is a positive integer greater than or equal to 2.

In an embodiment of the present application, i Doppler frequency shifts may be stored in a storage space of the receiver (for example, but not limited to, a non-volatile memory flash, or an eeprom). Based on this, the receiver obtains i Doppler frequency shifts corresponding to i satellite signals transmitted by the target satellite, including: the receiver reads i Doppler frequency shifts from the storage space to obtain i Doppler frequency shifts.

The i-th satellite signal described in S401 above is a digital intermediate frequency signal obtained by processing the i-th satellite signal transmitted by the target satellite received by the receiver through the RF front end. Optionally, in other implementations, the i-th satellite signal may also be a digital intermediate frequency signal obtained by processing the i-th satellite signal transmitted by the target satellite received by the receiver through RF amplification, down-conversion and quantization.

S402: The receiver determines a Doppler frequency shift search range according to i Doppler frequency shifts.

In the embodiment of the present application, the method for the receiver to determine the Doppler frequency shift search range according to i Doppler frequency shifts is the same as the method described in S220 above. For details not described in detail here, please refer to the relevant description of S220 above.

In the above, in combination with S401 and S402, a method for determining a Doppler frequency shift search range according to i Doppler frequency shifts corresponding to a target satellite is described. Next, a capture process of capturing a satellite signal to be captured transmitted by a target satellite according to a determined Doppler frequency shift search range provided by an embodiment of the present application is described.

403. The receiver determines a candidate Doppler frequency shift and a candidate pseudo code phase according to the Doppler frequency shift search range and the CA code.

In an embodiment of the present application, the Doppler shift search range and the pseudo-random code sequence corresponding to the CA code can constitute a two-dimensional coordinate system. Wherein, the abscissa and ordinate of the two-dimensional coordinate system represent the Doppler shift search range and the pseudo-random code sequence corresponding to the CA code, respectively. For the CA code of GPS, if the code step value is set to 0.5 chips, since the CA code is 1023 chips long, it is considered that the code phase has 2046 values in the capture of GPS. If the code step value is set to 1 chip, since the CA code is 1023 chips long, it is considered that the code phase has 1023 values in the capture of GPS. Wherein, one code period of the CA code is 20 milliseconds (ms). Exemplarily, referring to the two-dimensional coordinate system shown in FIG3B, in FIG3B, the abscissa of the two-dimensional coordinate system represents the range of the Doppler shift as [-6500Hz, 6500Hz], and the ordinate of the two-dimensional coordinate system represents the range of the pseudo-code phase as [0°, 1023°]. It can be understood that the search unit represented by any square shown in FIG. 3B is: the searched Doppler frequency shift (i.e., the candidate Doppler frequency shift described in the embodiment of the present application) and the searched pseudo code phase (the candidate pseudo code phase described in the embodiment of the present application). In the case where the candidate Doppler frequency shift and the candidate pseudo code phase corresponding to any square can successfully capture the satellite signal transmitted by the target satellite, the candidate Doppler frequency shift and the candidate pseudo code phase are respectively determined as the target Doppler frequency shift and the target pseudo code phase.

In an embodiment of the present application, the candidate Doppler shift and the candidate code phase can be selected in a two-dimensional coordinate system in a certain order, but the order of selection is not specifically limited. Exemplarily, taking the two-dimensional coordinate system shown in FIG3B as an example, the candidate Doppler shift and the candidate pseudo-code phase can be selected in sequence along the pseudo-code phase direction starting from the lower left corner of the two-dimensional coordinate system. In some implementations, if the code step value is set to 1 chip, the candidate Doppler shift and the candidate pseudo-code phase selected for the first time are the Doppler shift and the pseudo-code phase corresponding to the symbol "A1" in FIG3B, and the candidate Doppler shift and the candidate pseudo-code phase selected for the second time are the Doppler shift and the pseudo-code phase corresponding to the symbol "A2" in FIG3B, and so on. Without changing the Doppler shift, after selecting the pseudo-code phases of the first column in sequence, next, change the Doppler shift, and then select the pseudo-code phases of the second column in sequence. Taking FIG. 3B as an example, the Doppler frequency shift and pseudo code phase corresponding to the symbol "A1" are selected for the first time, and the Doppler frequency shift and pseudo code phase corresponding to the symbol "A2" are selected for the second time, until the selection of the pseudo code phase of the first column is completed. Thereafter, the Doppler frequency shift and pseudo code phase corresponding to the symbol "B1" are selected, until the selection of the pseudo code phase of the second column is completed. By analogy, the selection of all Doppler frequency shifts and pseudo code phases included in the two-dimensional coordinate system is completed.

In the embodiment of the present application, the steps described in S404 to S408 are repeatedly performed for each candidate Doppler frequency shift and candidate code phase until it can be determined that the receiver has successfully captured the satellite signal based on a pair of candidate Doppler frequency shift and candidate code phase, after which the process of capturing the satellite signal can be terminated.

S404, the receiver performs mixing processing on the received input signal #1 to be analyzed and the local carrier signal to obtain an I baseband signal and a Q baseband signal.

Among them, input signal #1 is the satellite signal transmitted by the target satellite received by the receiver and converted into a digital intermediate frequency signal after being processed by the RF front end. The frequency of the local carrier signal is the same as the candidate Doppler frequency shift. The I-channel baseband signal is obtained by mixing the input signal with the local carrier signal; the Q-channel baseband signal is obtained by mixing the input signal with the orthogonal signal of the local carrier signal. Exemplarily, Figure 3A shows the process of processing the input signal to be analyzed to obtain the I-channel baseband signal and the Q-channel baseband signal. Figure 3A shows that the input signal to be analyzed can be the input signal #1 described in S404 above, and the local oscillator shown in Figure 3A is used to generate a local carrier signal with the same frequency as the candidate Doppler frequency shift.

S405, the receiver performs correlation operations on the I baseband signal and the Q baseband signal respectively according to the candidate pseudo code phase to obtain correlation operation result 1 of the I baseband signal and correlation operation result 2 of the Q baseband signal.

Executing the above S405, i.e., the receiver performs correlation operations on the I-channel baseband signal and the Q-channel baseband signal respectively according to the candidate pseudo code phase to obtain correlation operation result 1 of the I-channel baseband signal and correlation operation result 2 of the Q-channel baseband signal, includes: the receiver adjusts the phase of the I-channel baseband signal and the Q-channel baseband signal respectively according to the candidate pseudo code phase, so that the adjusted phases of the I-channel baseband signal and the adjusted phases of the Q-channel baseband signal are the same as the candidate pseudo code phase; the receiver performs correlation operations on the adjusted I-channel baseband signal and the adjusted Q-channel baseband signal to obtain correlation operation result 1 of the I-channel baseband signal and correlation operation result 2 of the Q-channel baseband signal. Exemplarily, referring to FIG. 3A , the pseudo random code generator shown in FIG. 3A is used to generate a candidate pseudo random code.

S406, the receiver performs coherent integration operations on the correlation operation result 1 and the correlation operation result 2 respectively to obtain an integration result of the correlation operation result 1 and an integration result of the correlation operation result 2.

The coherent integration processing flow described in S406 above is the same as the coherent integration processing flow in the conventional technology, and will not be described in detail here.

S407, the receiver performs non-coherent integration processing on the modulus value of the integration result of the correlation operation result 1 and the modulus value of the integration result of the correlation operation result 2 to obtain a non-coherent integration processing result.

The incoherent integration processing flow described in S407 above is the same as the incoherent integration processing flow in the conventional technology, and will not be described in detail here.

S408: The receiver determines whether the receiver has successfully captured the input signal #1 according to the non-coherent integration processing result and the preset capture threshold.

In an embodiment of the present application, the receiver determines whether the receiver has successfully captured the input signal #1 based on the incoherent integration processing result and the preset capture threshold, including: if the receiver determines that the incoherent integration processing result exceeds the preset capture threshold, it is determined that the receiver has successfully captured the input signal #1; or, if the receiver determines that the incoherent integration processing result does not exceed the preset capture threshold, it is determined that the receiver has not captured the input signal #1.

In the embodiment of the present application, after executing the above S408, if it is determined that the receiver has successfully captured the input signal #1, then after executing the above S408, S409 is continued to be executed; if it is determined that the receiver has not captured the input signal #1, then after executing the above S408, S403 is continued to be executed, wherein, in this implementation, the candidate Doppler frequency shift and the candidate code phase described in S403 need to be updated, that is, the steps described in S403 to S408 are re-executed using the updated candidate Doppler frequency shift and the candidate code phase. Exemplarily,

S409: The receiver updates the Doppler frequency shift search range according to the candidate Doppler frequency shift to obtain an updated Doppler frequency shift search range.

After executing S408, continue to execute S409, that is, when the receiver successfully captures the candidate Doppler frequency shift and the candidate pseudo code phase When the satellite signal to be captured transmitted by the target satellite is acquired, the candidate Doppler frequency shift and the candidate pseudo code phase can be considered as the Doppler frequency shift and the pseudo code phase of the satellite signal to be captured transmitted by the target satellite that are finally successfully captured. In practical applications, the Doppler frequency shift corresponding to a satellite is estimable. Based on this, in the embodiment of the present application, the Doppler frequency shift range described in S402 can also be updated according to the Doppler frequency shift corresponding to the target satellite determined in S409 (i.e., the candidate Doppler frequency shift described in S409).

In the embodiment of the present application, in some implementations, the above S409 is executed, that is, the receiver updates the Doppler frequency shift search range according to the candidate Doppler frequency shift to obtain the updated Doppler frequency shift search range, including: if the candidate Doppler frequency shift is greater than the maximum value of the Doppler frequency shift search range, the maximum value of the Doppler frequency shift search range is updated using the candidate Doppler frequency shift; if the candidate Doppler frequency shift is greater than the minimum value of the Doppler frequency shift search range, the minimum value of the Doppler frequency shift search range is updated using the candidate Doppler frequency shift. Optionally, in other implementations, the receiver updates the Doppler frequency shift search range according to the candidate Doppler frequency shift to obtain the updated Doppler frequency shift search range, including: determining a new mean square error according to the above multiple candidate Doppler frequency shifts and the candidate Doppler frequency shift described in the above S409; and determining the updated Doppler frequency shift search range according to the new mean square error.

It should be understood that the method shown in FIG. 4 is only for illustration and does not constitute any limitation on the satellite signal capture method provided in the embodiment of the present application. It is understandable that the method shown in FIG. 4 is described by taking the receiver capturing a satellite signal transmitted by a target satellite as an example. Optionally, the receiver in the method shown in FIG. 4 can also capture satellite signals transmitted by multiple target satellites, wherein the principle of the receiver capturing the satellite signal transmitted by each target satellite is the same. The implementation method of determining the Doppler frequency shift search range of the target satellite according to the i Doppler frequency shifts of the target satellite shown in FIG. 4 is only for illustration. In other words, other calculation methods can also be used to determine the Doppler frequency shift search range of the target satellite according to the i Doppler frequency shifts of the target satellite. For example, the CA code can also be replaced by the P code, and accordingly, the range of the pseudo-code coordinates of the two-dimensional coordinate system needs to be replaced by the range of the random code sequence corresponding to the P code. For example, in the above implementation, the two-dimensional coordinate system is searched in a serial search manner. Optionally, the two-dimensional coordinate system can also be searched in a parallel search manner, wherein the parallel search method is the same as the parallel search method described in the traditional technology and will not be described in detail here.

In an embodiment of the present application, the receiver determines the Doppler frequency shift search range used by the receiver when searching for the satellite signal transmitted by the target satellite at the current moment according to the i Doppler frequency shifts corresponding to the i satellite signals transmitted by the target satellite at the historical moment. Wherein, each Doppler frequency shift represents the offset of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal. Thereafter, the receiver searches for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range. That is to say, in the above implementation, the Doppler frequency shift search range used by the receiver when capturing the satellite signal transmitted by the target satellite is associated with the Doppler frequency shift corresponding to the satellite signal transmitted by the target satellite in history. In this way, the Doppler frequency shift search range searched by the receiver can be effectively narrowed, thereby improving the efficiency of the receiver in capturing satellite signals. In addition, when the receiver successfully captures the satellite signal to be captured transmitted by the target satellite according to the Doppler frequency shift and pseudo-random code currently being searched, the Doppler frequency shift search range can also be updated using the Doppler frequency shift currently being searched, which is helpful to improve the accuracy of the Doppler frequency shift search range. In summary, the satellite signal capture method provided in the embodiment of the present application can improve the efficiency of capturing satellite signals.

In the above, in combination with FIG. 1 to FIG. 4, the application scenarios and satellite signal capture methods provided by the present application are described in detail. Method. Below, the satellite signal acquisition device, equipment and system provided by the present application are introduced in conjunction with Figures 5 to 7. It should be understood that the satellite signal acquisition method described above corresponds to the satellite signal acquisition device, equipment and system described below, and the content not described in detail below can refer to the relevant description in the above method embodiment.

Corresponding to a satellite signal capturing method provided in an embodiment of the present application, an embodiment of the present application provides a satellite signal capturing device.

FIG5 is a schematic diagram of the structure of a satellite signal acquisition device provided by an embodiment of the present application. As shown in FIG5, the satellite signal acquisition device includes an acquisition module 510, a determination module 520, and a search module 530. The functions of each module in the acquisition module 510, the determination module 520, and the search module 530 are described in detail below.

The acquisition module 510 is used to: acquire multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by the target satellite, wherein the multiple satellite signals and the multiple Doppler frequency shifts correspond one to one; each Doppler frequency shift represents the offset of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal; the determination module 520 is used to: determine the Doppler frequency shift search range according to the multiple Doppler frequency shifts; the search module 530 is used to: search for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range, so as to capture the satellite signal to be captured.

In one possible design, the determination module 520 is further used to: determine the maximum Doppler frequency shift among the multiple Doppler frequency shifts as the maximum search value of the search range, and determine the minimum Doppler frequency shift among the multiple Doppler frequency shifts as the minimum search value of the search range.

Optionally, in another possible design, the determination module 520 is further used to: determine the mean square error of the multiple Doppler frequency shifts based on the multiple Doppler frequency shifts; determine the Doppler frequency shift search range based on the mean square error, wherein the maximum Doppler frequency shift included in the search range is the product of a preset threshold and the mean square error, and the minimum Doppler frequency shift included in the search range is the inverse of the maximum Doppler frequency shift.

Optionally, in another possible design, the search module 530 is also used to: determine multiple Doppler frequency shifts to be searched according to a preset frequency step value and the Doppler frequency shift search range; mix the acquired input signal to be analyzed and the local carrier signal to obtain an I-channel baseband signal and a Q-channel baseband signal, wherein the frequency of the local carrier signal is the same as the searched Doppler frequency shift, and the multiple Doppler frequency shifts to be searched include the searched Doppler frequency shift; the input signal to be analyzed is a digital intermediate frequency signal obtained after the satellite signal to be captured received by the receiver is processed by the RF front end; the I-channel baseband signal is obtained by mixing the input signal to be analyzed with the local carrier signal; the Q-channel baseband signal is obtained by mixing the input signal to be analyzed with the orthogonal signal of the local carrier signal; and according to the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code, the satellite signal to be captured transmitted by the target satellite is searched to capture the satellite signal to be captured.

Optionally, in another possible design, the search module 530 is further used to: move the pseudo-random code sequence of the pseudo-random code in units of a preset number of chips in the Doppler frequency shift of the first search, and perform correlation operations with the baseband signal of the I path and the baseband signal of the Q path respectively to obtain a first correlation result of the I path and a second correlation result of the Q path, wherein the Doppler frequency shift of the first search is the Doppler frequency shift of the search; perform coherent integration operations on the first correlation result and the second correlation result respectively, Obtain a first integration result of the first correlation result and a second integration result of the second correlation result; perform incoherent integration processing on the modulus value of the first integration result and the modulus value of the second integration result to obtain a first incoherent integration processing result; compare the first incoherent integration processing result with a preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the first incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the first incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.

Optionally, in another possible design, when the first non-coherent integration processing result does not exceed a preset capture threshold, and the movement in units of a preset number of code chips exceeds the code period of the pseudo-random code, the search module 530 is further used to: move the pseudo-random code sequence of the pseudo-random code in units of the preset number of code chips in the second search Doppler frequency shift, and perform correlation operations with the baseband signal of the I path and the baseband signal of the Q path respectively to obtain a third correlation result of the I path and a fourth correlation result of the Q path, wherein the Doppler frequency shift of the second search is the Doppler frequency shift of the search, and the Doppler frequency shift of the second search and the Doppler frequency shift of the first search are two different Doppler frequencies. shift; respectively perform integration operations on the third correlation result and the fourth correlation result to obtain a third integration result of the third correlation result and a fourth integration result of the fourth correlation result; perform incoherent integration processing on the modulus value of the third integration result and the modulus value of the fourth integration result to obtain a second incoherent integration processing result; compare the second incoherent integration processing result with the preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the second incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the second incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.

Optionally, in another possible design, the device also includes an updating module 540, and the multiple Doppler shifts to be searched include a target Doppler shift. After searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler shift search range to capture the satellite signal to be captured, the updating module 540 is used to: in a case where the satellite signal to be captured is successfully captured according to the target Doppler shift and the pseudo-random code sequence of the pseudo-random code, if the search range does not include the target Doppler shift, perform the following operations: if the target Doppler shift is greater than the maximum Doppler shift included in the search range, update the maximum Doppler shift included in the search range to the target Doppler shift; or, if the target Doppler shift is greater than the minimum Doppler shift included in the search range, update the minimum Doppler shift included in the search range to the target Doppler shift.

Optionally, in another possible design, the multiple Doppler frequency shifts are stored in a storage space of the receiver, and the acquisition module 510 is further used to: read the multiple Doppler frequency shifts from the storage space.

Corresponding to a satellite signal capture method provided in an embodiment of the present application, an embodiment of the present application provides a satellite signal capture device.

FIG6 is a schematic diagram of the structure of a satellite signal acquisition device provided in an embodiment of the present application. As shown in FIG6 , the device includes a memory 601, a processor 602, a communication interface 603, and a communication bus 604. The memory 601, the processor 602, and the communication interface 603 are connected to each other through the communication bus 604.

The memory 601 may be a read only memory (ROM), a static storage device, a dynamic storage device or a random access memory (RAM). The memory 601 may store a program. When the program stored in the memory 601 is processed When the processor 602 executes, the processor 602 and the communication interface 603 are used to execute each step of the satellite signal acquisition method of the embodiment of the present application.

Processor 602 can adopt a general-purpose central processing unit (CPU), a microprocessor, an application specific integrated circuit (ASIC), a graphics processing unit (GPU) or one or more integrated circuits to execute relevant programs to implement the functions required to be performed by the units in the satellite signal acquisition device of the embodiment of the present application, or to execute the various steps of the satellite signal acquisition method of the embodiment of the present application.

The processor 602 may also be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the satellite signal acquisition method provided by the present application may be completed by an integrated logic circuit of hardware or software instructions in the processor 602. The above-mentioned processor 602 may also be a general-purpose processor, a digital signal processor (digital signal processing, DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application may be directly embodied as being executed by a hardware decoding processor, or may be executed by a combination of hardware and software modules in a decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 601, and the processor 602 reads the information in the memory 601, and combines its hardware to complete the functions required to be performed by the units included in the satellite signal capture device of the embodiment of the present application, or executes the satellite signal capture method of the method embodiment of the present application.

The communication interface 603 uses a transceiver device such as but not limited to a transceiver to implement communication between the device shown in FIG. 6 and other devices or a communication network.

The communication bus 604 may include a path for transmitting information between the various components of the device shown in FIG. 6 (eg, the memory 601 , the processor 602 , and the communication interface 603 ).

Corresponding to a satellite signal acquisition method provided in an embodiment of the present application, an embodiment of the present application provides a system.

FIG7 is a schematic diagram of the structure of a system provided by an embodiment of the present application. As shown in FIG7, the system includes a satellite signal acquisition device 710, wherein the satellite signal acquisition device 710 may be the satellite signal acquisition device shown in FIG6 above. In other words, the satellite signal acquisition device 710 has the same functions as the satellite signal acquisition device shown in FIG6 above.

An embodiment of the present application also provides a computer-readable storage medium, which includes a computer program. When the computer-readable storage medium is run on a computer, the computer is enabled to execute the satellite signal acquisition method provided by the above method embodiment.

The present application also provides a chip system, including a processor, for calling and running a computer program from a memory, so that a device equipped with the chip system executes the satellite signal acquisition method provided in the above method embodiment.

An embodiment of the present application also provides a computer program product comprising instructions. When the computer program product is run on a computer, the computer is enabled to execute the satellite signal acquisition method provided by the above method embodiment.

Those skilled in the art will appreciate that the units and algorithm steps of each example described in the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software, Depending on the specific application and design constraints of the technical solution, professional and technical personnel may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program codes.

The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

A satellite signal acquisition method, characterized in that the method comprises:

Acquire multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by the target satellite, wherein the multiple satellite signals correspond to the multiple Doppler frequency shifts one by one; each Doppler frequency shift represents an offset of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal;

Determining a Doppler frequency shift search range according to the multiple Doppler frequency shifts;

The satellite signal to be captured transmitted by the target satellite is searched according to the pseudo-random code and the Doppler frequency shift search range, so as to capture the satellite signal to be captured.
The method according to claim 1, characterized in that the step of determining a Doppler frequency shift search range according to the multiple Doppler frequency shifts comprises:

A maximum Doppler frequency shift among the plurality of Doppler frequency shifts is determined as a maximum search value of the search range, and a minimum Doppler frequency shift among the plurality of Doppler frequency shifts is determined as a minimum search value of the search range.
The method according to claim 1, characterized in that the step of determining a Doppler frequency shift search range according to the multiple Doppler frequency shifts comprises:

Determining mean square errors of the multiple Doppler frequency shifts according to the multiple Doppler frequency shifts;

The Doppler frequency shift search range is determined according to the mean square error, wherein a maximum Doppler frequency shift included in the search range is a product of a preset threshold and the mean square error, and a minimum Doppler frequency shift included in the search range is an inverse of the maximum Doppler frequency shift.
The method according to any one of claims 1 to 3, characterized in that the step of searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range to capture the satellite signal to be captured comprises:

Determining a plurality of Doppler frequency shifts to be searched according to a preset frequency step value and the Doppler frequency shift search range;

The acquired input signal to be analyzed and the local carrier signal are mixed to obtain an I-channel baseband signal and a Q-channel baseband signal, wherein the frequency of the local carrier signal is the same as the Doppler frequency shift to be searched, and the multiple Doppler frequency shifts to be searched include the Doppler frequency shift to be searched; the input signal to be analyzed is a digital intermediate frequency signal obtained after the satellite signal to be captured received by the receiver is processed by the radio frequency front end; the I-channel baseband signal is obtained by mixing the input signal to be analyzed with the local carrier signal; the Q-channel baseband signal is obtained by mixing the input signal to be analyzed with the orthogonal signal of the local carrier signal;

According to the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code, a satellite signal to be captured transmitted by the target satellite is searched to capture the satellite signal to be captured.
The method according to claim 4 is characterized in that the step of searching for the satellite signal to be captured transmitted by the target satellite according to the I-channel baseband signal, the Q-channel baseband signal and the pseudo-random code sequence corresponding to the pseudo-random code to capture the satellite signal to be captured comprises:

The Doppler frequency shift of the first search is used to move the pseudo-random code sequence of the pseudo-random code by a preset number of chips, and respectively perform correlation operations with the baseband signal of the I path and the baseband signal of the Q path to obtain a first correlation result of the I path and a second correlation result of the Q path, wherein the Doppler frequency shift of the first search is the Doppler frequency shift of the search;

Performing coherent integration operations on the first correlation result and the second correlation result respectively to obtain a first integration result of the first correlation result and a second integration result of the second correlation result;

Performing incoherent integration processing on the modulus value of the first integration result and the modulus value of the second integration result to obtain a first incoherent integration processing result;

The first incoherent integration processing result is compared with a preset capture threshold to determine whether the satellite signal to be captured is successfully captured; if the incoherent integration processing exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the incoherent integration processing does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.
The method according to claim 5, characterized in that, when the first non-coherent integration processing result does not exceed the preset capture threshold, and the movement in units of a preset number of chips exceeds the code period of the pseudo-random code, the method further comprises:

The Doppler frequency shift of the second search is used to move the pseudo-random code sequence of the pseudo-random code in units of the preset number of chips, and respectively perform correlation operations with the baseband signal of the I path and the baseband signal of the Q path to obtain a third correlation result of the I path and a fourth correlation result of the Q path, wherein the Doppler frequency shift of the second search is the Doppler frequency shift of the search, and the Doppler frequency shift of the second search and the Doppler frequency shift of the first search are two different Doppler frequency shifts;

Performing integration operations on the third correlation result and the fourth correlation result respectively to obtain a third integration result of the third correlation result and a fourth integration result of the fourth correlation result;

Perform incoherent integration processing on the modulus value of the third integration result and the modulus value of the fourth integration result to obtain a second incoherent integration processing result; compare the second incoherent integration processing result with the preset capture threshold to determine whether the satellite signal to be captured is successfully captured; wherein, if the second incoherent integration processing result exceeds the preset capture threshold, the satellite signal to be captured is successfully captured; if the second incoherent integration processing result does not exceed the preset capture threshold, the satellite signal to be captured is not successfully captured.
The method according to any one of claims 4 to 6, characterized in that the multiple Doppler frequency shifts to be searched include a target Doppler frequency shift, and after searching for the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range to capture the satellite signal to be captured, the method further comprises:

In the case where the satellite signal to be captured is successfully captured according to the target Doppler frequency shift and the pseudo-random code sequence of the pseudo-random code, if the search range does not include the target Doppler frequency shift, the following operations are performed:

If the target Doppler shift is greater than the maximum Doppler shift included in the search range, then updating the maximum Doppler shift included in the search range to the target Doppler shift; or,

If the target Doppler shift is greater than the minimum Doppler shift included in the search range, the minimum Doppler shift included in the search range is The small Doppler frequency shift is updated to the target Doppler frequency shift.
The method according to any one of claims 1 to 7, characterized in that the multiple Doppler frequency shifts are stored in the storage space of the receiver, and the acquiring multiple Doppler frequency shifts corresponding to the multiple satellite signals transmitted by the target satellite comprises:

The plurality of Doppler frequency shifts are read from the storage space.
A satellite signal acquisition device, characterized in that the device comprises:

An acquisition device is used to acquire multiple Doppler frequency shifts corresponding to multiple satellite signals transmitted by a target satellite, wherein the multiple satellite signals correspond to the multiple Doppler frequency shifts one by one; each Doppler frequency shift represents the offset of the frequency of the input signal relative to the frequency of the satellite signal corresponding to each Doppler frequency shift when the receiver receives the input signal;

A determining device, configured to determine a Doppler frequency shift search range according to the plurality of Doppler frequency shifts;

The searching device is used to search the satellite signal to be captured transmitted by the target satellite according to the pseudo-random code and the Doppler frequency shift search range, so as to capture the satellite signal to be captured.
A satellite signal acquisition device, characterized in that it comprises at least one processor, wherein the at least one processor is used to couple with a memory, read and execute instructions in the memory, so as to implement the method as described in any one of claims 1 to 8.