JP2000266834A - Gps accepting station with communication function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a maximum operation speed without increasing a consumption power by a circuit as small as possible at a GPS accepting station with a communication function. SOLUTION: The station includes a memory 13 for storing outputs of an RF front end part 12 which frequency converts GPS signals received by a GPS antenna 11, a switching device 14 for switching signals read out from the memory 13 and signals outputted from the RF front end part 12, a control circuit 19 for shutting the supply of a power source to the RF front end part 12 while signals read out from the memory 13 are outputted from the switching device 14, a means 18 for generating dummy noise code signals of satellite numbers informed from a base station, a plurality of correlators 16 for obtaining a correction to the pseudo noise code signals, and a plurality of automatic tracking parts 17 for outputting data for position calculation to be sent to the base station. In this constitution, once signals from a GPS receiving part are stored inside the memory, operations can be made at high speed and, the problem of wrong locking which is generally in a trade-off relationship to a high-speed performance can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS (Global Positioning System) having communication means such as a mobile phone, a satellite mobile phone, and a PHS.
The present invention relates to a receiving terminal of a bal Positioning System (bal Positioning System).

[0002]

2. Description of the Related Art FIG. 5 shows a schematic configuration of a GPS receiving terminal with a communication function. In the figure, SV1 to SV3 are GPS visible satellites, and information such as satellite numbers and Doppler frequencies are obtained from signals received by the base station 30 via the GPS antenna 31 and transmitted to the GPS receiving terminal 10 via the communication means 22 and 21. Will be informed. The GPS receiving terminal 10 performs only frequency synchronization and phase synchronization processing for capturing and tracking signals from visible satellites received by the GPS antenna 11, and transmits data necessary for calculating its own current position to the communication means. 2
The information is sent to the base station 30 via the terminals 1 and 22. In the base station 30, G
G based on the data sent from the PS receiving terminal 10
The position and the like of the PS receiving terminal 10 are calculated. In order to increase the accuracy of the position calculation, the base station 30 may use DGPS correction information received from the FM broadcast receiving antenna 32 or the like. The calculated location information of the terminal 10 is used by the base station 30 or, depending on the application, the communication means 22, 2
1 is also transmitted to the GPS receiving terminal 10.

[0003]

SUMMARY OF THE INVENTION This GP with a communication function
The S receiving terminal is used for a personal navigation system, a search for a wandering elderly person, a position detection system for crime prevention, and the like, and it is desired to reduce the size and weight so as to be suitable for carrying, and enable long-time use. Therefore, it is desired to reduce the power consumption of the battery.

In a GPS receiving terminal with a communication function,
As described above, it is not necessary to perform the operation for determining the position in the terminal body, and the operation for determining the position is performed in the base station. Also,
Since information related to GPS visible satellites is also given from the base station, the GP built into the car navigation system
Unlike the S receiving device, it is not necessary to perform the search processing for knowing the satellite number of the visible satellite. For this reason, compared to a GPS receiving terminal without a communication function, the required circuits are smaller and the time required for positioning can be reduced.

However, since the communication function is provided, when the GPS reception function and the communication function are used at the same time, the power consumption increases. Further, if a plurality of correlators are simultaneously operated in order to speed up a correlation operation for achieving phase synchronization, power consumption further increases. Further, if the speed of the correlation calculation is increased, the possibility of erroneous satellite lock increases.

The present invention has been made in view of such circumstances, and it is an object of a GPS receiving terminal with a communication function to obtain a maximum operation speed with a circuit as small as possible without increasing power consumption. is there.

[0007]

According to the present invention, a G having a communication function is provided.
The basic principle of the PS receiving terminal is to take the signal output from the GPS receiving unit into the memory once and use it repeatedly several times. The configuration allows for maximum efficiency.

Specifically, according to the first aspect of the present invention, G
A PS antenna 11, a GPS receiving unit (RF front end unit 12) for frequency-converting a GPS signal received by the GPS antenna 11, a memory 13 for storing signals output from the GPS receiving unit, and a signal read from the memory 13. A switch 14 for switching between a signal and a signal output from the GPS receiver; and a control circuit 19 for shutting off power supply to the GPS receiver during a period in which a signal read from the memory 13 is output from the switch 14. Communication means 21 for exchanging signals with a base station 30 having an arithmetic function for calculating terminal positions and the like
A pseudo-noise code signal generator 18 for generating pseudo-noise code signals for capturing visible satellites in a plurality of different phases based on information on visible satellites notified from the base station 30 by the communication means 21; A plurality of correlators 16 for obtaining a correlation between the signal output from the signal 14 and the pseudo-noise code signal.
And a plurality of automatic tracking units 17 that output data for position calculation to be sent to the base station 30 via the communication unit 21.

Here, the number of the auto-tracking unit 17 is smaller than that of the correlator 16, and a plurality of pseudo-noise code signals of the same frequency and shifted in phase are input to the plurality of correlators 16, and output from the switch 14. A plurality of correlations having different phases are simultaneously generated for a pseudo-noise code signal having the same satellite number by calculating a correlation with a signal, and a phase having a peak carrier correlation value is used for phase synchronization of one automatic tracking unit. Thereby, the time until the phase synchronization is established can be reduced. Further, by calculating the sum of a plurality of carrier correlation values near the peak and comparing the sum with a predetermined threshold, a steep peak can be excluded as an erroneous satellite lock. Further, the process of sampling the signal from the GPS receiving unit a plurality of times during 1 ms, which is the code length of the C / A code, and storing it in the memory is continued for a predetermined time, and the code of the C / A code is started from the sampling start time. The carrier-to-noise ratio can be increased by inputting the correlated data by shifting the time axis every 1 ms and superimposing the data on an integral multiple of the length of 1 ms.

[0010] Further, the calculation time can be further shortened by diverting the offset peculiar to the circuit obtained when the first satellite is captured and tracked during the capture and tracking of the second and subsequent satellites. After capturing and tracking the first satellite,
When acquiring and tracking the second and subsequent satellites, a specific chip of the pseudo noise code of the first satellite (for example, the first chip) and the same chip of the pseudo noise code of the second and subsequent satellites are received. Alternatively, the time difference between the two may be calculated in units of chips and transmitted to the base station. In addition, when accumulating the signal from the GPS receiver in the memory, the amount of accumulation is variable, so that the positioning time can be shortened when the reception condition is good.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG.
FIG. 2 is a block diagram illustrating a configuration of a PS receiving terminal 10 as an example. In the figure, reference numeral 11 denotes a GPS antenna, and 12 denotes an RF front end unit as a GPS receiving unit, which receives a 1.57542 GHz high frequency from a GPS satellite, converts the frequency, and outputs a digital signal of about several MHz.
Reference numeral 13 denotes a memory that stores digital signals output from the RF front-end unit 12 over a predetermined time.
Reference numeral 14 denotes a switch for selecting whether to send the data output from the RF front-end unit 12 to the correlator 16 as it is, or to send to the correlator 16 the data once read out of the data stored in the memory 13. . Reference numeral 15 denotes an adder, which is used in Example 4 to improve the carrier-to-noise ratio by adding data every 1 ms. Reference numeral 16 denotes a correlator that operates n (n is an integer of 3 or more) correlators simultaneously so that phase synchronization can be quickly established. That is, the pseudo-noise code signal generator 18 generates a pseudo-noise code of the number of the visible satellite, and generates n pseudo-noise code signals whose phases are slightly shifted from the first to n-th pseudo-noise code signals. And input to the correlator 16 of the
4 is correlated with the signal output from the fourth signal. As a result, the phase at which the carrier correlation value reaches a peak can be found in a short time. Reference numeral 17 denotes an automatic tracking unit, and m (m
Is an integer of 3 or more and n> m), locks signals from different visible satellites and transmits them to the base station 30 via the communication means 21 and 22 in FIG. The base station 30 analyzes signals from three or more satellites and
The position of the S receiving terminal 10 is calculated. The base station 30 notifies the GPS receiving terminal 10 of information about visible satellites via the communication means 22 and 21 in advance. This eliminates the need for the GPS receiving terminal to search for the number of the visible satellite, and the plurality of correlators 16 start from the processing for achieving phase synchronization with the pseudo-noise code of the satellite number notified from the base station 10. And the time required for positioning can be reduced. In addition, the control circuit 19 controls the operation of each unit, and stops the operation of the RF front-end unit 12 while data is being read from the memory 13 to the correlator 16, thereby reducing power consumption. .

In this embodiment, (n-m + 1) correlators 16 share one automatic tracking unit 17. When the number of correlators 16 and the number of automatic tracking units 17 are different,
A plurality of correlators are assigned to one automatic tracking unit. In general, the number of the auto-tracking units is only required to be equal to the number of visible satellites, and thus is often smaller than the number of correlators. Also, 1
The circuit-specific offset (that is, the difference between the pseudo-noise code from the satellite and the pseudo-noise code of the receiver) obtained when the second satellite is acquired and tracked is obtained when the second and subsequent satellites are acquired and tracked. By diverting, the second and subsequent satellites can be easily captured and tracked. In addition, the first satellite
After the tracking, when capturing and tracking the second and subsequent satellites, a specific chip (for example, the first chip) of the pseudo noise code of the first satellite and the same chip of the second and subsequent satellites are used. The difference in reception time may be calculated in units of the number of chips and transmitted to the base station.

(Embodiment 2) FIG. 2 is an explanatory view of the second embodiment. The curve in the figure shows the curve of the carrier correlation value. The horizontal axis of the graph is the phase shift, the vertical axis is the carrier correlation value, and the point x plotted on the graph is the carrier correlation value obtained by the first to n-th correlators at a certain time. is there. As described above, since a plurality of carrier correlation values are obtained simultaneously by a plurality of correlators, a phase at which the carrier correlation value has a peak can be obtained in a short time. When the GPS receiver and the correlator are not operated simultaneously, but the GPS receiver is operating, the operation of the correlator is stopped, the received data is temporarily stored in the memory, and the data is stored from the memory. In the reading period, G
By stopping the operation of the PS receiving unit and starting the operation of the correlator, the peak of the power consumption can be reduced. Furthermore, the speed of reading data from the memory is made faster than the speed of storing data in the memory, so that the speed of the correlation operation in the correlator can be increased, and the data from the GPS receiver is directly used. Compared to the case, the time required to capture all visible satellites can be reduced, and the total power consumption can be reduced accordingly.

(Embodiment 3) FIG. 3 is an explanatory view of the third embodiment. Two curves in the figure show curves of the carrier correlation value. The horizontal axis of the graph is the phase shift, the vertical axis is the carrier correlation value, and the point x plotted on the graph is the carrier correlation value obtained by the first to n-th correlators at a certain time. is there. The curve on the left is the curve of the carrier correlation value of the desired satellite (SV1), and the curve on the right is the curve of the carrier correlation value of another satellite (SV2) other than the desired satellite. When there is an obstruction between the desired satellite SV1 and the receiver and the reception condition is poor, and there is little obstruction between the other satellite SV2 which is not the desired satellite and the receiver, the signal received from each satellite in this way. The intensity may be approximately equal. In such a case, it is necessary to set a low threshold value as indicated by a broken line, and if the correlation value is only one point, the correlation of another satellite which is not the desired satellite is also the same as the correlation of the desired satellite. It can be mistaken. But,
In general, since the curve of the correlation value of another satellite that is not the desired satellite is steeper than the curve of the correlation value of the desired satellite,
Taking the sum of the correlation values represented by × and using the sum as a criterion, when the correlation is determined by only one correlation value, the correlation value of another satellite that is not the desired satellite is used as the correlation value of the desired satellite. It is possible to avoid occurrence of an erroneous satellite lock mistaken for the value.

(Embodiment 4) FIG. 4 is an explanatory view of claim 4. In this example, when data output from the GPS receiving unit is stored in the memory, sampling is performed 2048 times per 1 ms, and the time axis is shifted every 1 ms.
A state where the data is overlapped by 3 ms and stored in another address of the memory is shown. Here, 1 ms refers to the pseudo noise code (PN code) of C / C
This corresponds to the code length of the A code. When the data stored at the different address is read from the memory and sent to the correlator,
The superimposed data also appears to the correlator as if it were sampled 2048 times in 1 ms, but the carrier to noise ratio is improved. This is because the carrier component has a correlation every 1 ms, which is the code length of the C / A code, but the noise component has a Gaussian distribution, and when superimposed, the increase rate of the carrier component exceeds the increase rate of the noise component. is there. This makes it possible to increase the carrier-to-noise ratio and minimize the influence of noise components with a simple circuit configuration. In the case of performing a process of overlaying data in a memory by shifting the time axis as in the present embodiment, a large amount of data to be stored in the memory is required. By omitting the above processing, the amount of data stored in the memory can be reduced, and the processing can be speeded up.

In the present embodiment, an example has been described in which data superimposed by shifting the time axis is stored at another address of the memory 13. However, as shown in FIG.
In the case where the adder 15 is arranged between the correlator 16 and the correlator 16,
4 ms of data shown in FIG.
4, the data is read out and stored in the buffer of the adder 15, and the data after the addition by shifting the time axis as shown in FIG. 4B is output from the adder 15 at a rate of 2048 samples per 1 ms. May be output. In this case, the capacity of the memory 13 can be reduced.

[0017]

According to the first aspect of the present invention, by temporarily storing a signal from the GPS receiving unit in the memory,
The operation can be performed at high speed, and the problem of erroneous lock, which is usually in a trade-off relationship with high speed, can be avoided. In addition, since the power supply to the GPS receiving unit can be shut off during a period in which a signal is being read from the memory, power consumption can be reduced and the circuit scale can be reduced.

According to the second aspect of the present invention, a plurality of pseudo-noise code signals having the same frequency but shifted in phase are input to a plurality of correlators, and a correlation with a signal output from the switch is obtained. By simultaneously generating a plurality of correlations having different phases with respect to the pseudo-noise code signal of the same satellite number, the peak of the carrier correlation value can be calculated at high speed. According to the third aspect of the present invention, the sum of the vicinity of the peaks of the plurality of carrier correlation values is obtained and compared with a predetermined threshold value. Can be prevented from being locked to the signal.

According to the fourth aspect of the present invention, the process of sampling the signal from the GPS receiving section a plurality of times during the 1 ms which is the code length of the C / A code and storing the signal in the memory is continued for a predetermined time, The data obtained by superimposing the data corresponding to an integer multiple of 1 ms, which is the code length of the C / A code from the sampling start time, by shifting the time axis every 1 ms and inputting the data to the correlator, is used as a carrier pair. The noise ratio can be increased, and the difference between the Doppler frequency from the base station and the actual Doppler frequency can be sensed.

According to the fifth aspect of the present invention, the offset unique to the circuit obtained when the first satellite is captured and tracked is diverted when capturing and tracking the second and subsequent satellites. The time required for capturing and tracking satellites beyond the eye can be reduced. According to the invention of claim 6, after the first satellite is captured and tracked, when the second and subsequent satellites are captured and tracked, the specific chip of the pseudo-noise code of the first satellite and the second chip are used. The difference between the times of receiving the same chip of the pseudo-noise code of the second and subsequent satellites is calculated in chip units and transmitted to the base station, so the time required for acquisition and tracking of the second and subsequent satellites is reduced. Can be shortened. According to the invention of claim 7, when the signal from the GPS receiving unit is stored in the memory, the amount of storage can be made variable, so that high-speed correlation can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a GPS receiving terminal with a communication function of the present invention.

FIG. 2 is an explanatory diagram of the invention of claim 2;

FIG. 3 is an explanatory view of the invention of claim 3;

FIG. 4 is an explanatory view of the invention of claim 4;

FIG. 5 is an explanatory diagram showing a usage state of a conventional GPS receiving terminal with a communication function.

[Explanation of symbols]

 Reference Signs List 10 GPS receiving terminal 11 GPS antenna 12 RF front end unit 13 Memory 14 Switcher 15 Adder 16 Correlator 17 Automatic tracking unit 18 Pseudo noise code generator 19 Control circuit 21 Communication means (GPS receiving terminal side) 22 Communication means (base) (Station side) 30 base stations

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (7)

[Claims] 1. A GPS antenna, a GPS receiver for frequency-converting a GPS signal received by a GPS antenna, a memory for storing a signal output from the GPS receiver, a signal read from the memory and a signal from the GPS receiver. A switch for switching a signal to be output, and a GP during a period in which a signal read from the memory is output from the switch.
A control circuit for shutting off the power supply to the S receiver, communication means for exchanging signals with a base station having an arithmetic function for terminal position and the like, and a visible satellite based on information of the visible satellite notified from the base station by the communication means A pseudo-noise code signal generator for generating pseudo-noise code signals for capturing signals at a plurality of different phases, a plurality of correlators for obtaining a correlation between the signal output from the switch and the pseudo-noise code signal, and communication means And a plurality of automatic tracking units for outputting data for position calculation to be sent to the base station via the communication unit
S receiving terminal. 2. The automatic tracking unit according to claim 1, wherein the number of the auto-tracking units is smaller than that of the correlators. By calculating the correlation with the signal,
A GPS receiver with a communication function, wherein a plurality of correlations having different phases are simultaneously generated for pseudo-noise code signals having the same satellite number, and a phase at which a carrier correlation value becomes a peak is used for phase synchronization of one automatic tracking unit. Terminal. 3. The GPS receiving terminal with a communication function according to claim 2, wherein a sum of a plurality of carrier correlation values near the peak is compared with a predetermined threshold. 4. The method according to claim 1, wherein the process of sampling the signal from the GPS receiving unit a plurality of times during 1 ms, which is the code length of the C / A code, and accumulating the signal in the memory is continued for a predetermined time, and the sampling is started. A communication function characterized in that, for data corresponding to an integral multiple of 1 ms, which is the code length of the C / A code from time, data obtained by superimposing the data by shifting the time axis every 1 ms is used as an input to the correlator. With GPS receiver. 5. The method according to claim 1, wherein the circuit-specific offset obtained when the first satellite is acquired and tracked is:
A GPS receiving terminal with a communication function, wherein the GPS receiving terminal is used for capturing and tracking a second and subsequent satellites. 6. The method according to claim 1, wherein after capturing and tracking the first satellite, when capturing and tracking the second and subsequent satellites, a specific chip of the pseudo noise code of the first satellite is used. A GPS receiving terminal with a communication function, which calculates a difference in time for receiving the same chip of the pseudo noise code of the second and subsequent satellites in units of the number of chips and transmits the result to a base station. 7. The GPS receiving terminal with a communication function according to claim 1, wherein when storing the signal from the GPS receiving unit in the memory, the amount of the storage is variable.