CN105634851B - Measuring device capable of generating user-defined data file quadrature amplitude modulation signal and modulation method thereof - Google Patents
Measuring device capable of generating user-defined data file quadrature amplitude modulation signal and modulation method thereof Download PDFInfo
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Abstract
The invention discloses a measuring device capable of generating a user-defined data file quadrature amplitude modulation signal and a modulation method thereof, wherein the measuring device comprises a system control unit, a quadrature amplitude modulation unit and a quadrature amplitude control unit, when a quadrature amplitude modulation source is a user-defined data file, a baseband rate control module generates an original file baseband clock and an original file modulation clock according to a baseband rate value and a modulation mode; the storage control module generates original file baseband data according to the original file baseband clock and the custom data file; the bit width conversion module performs bit width conversion on the baseband data of the original file according to the modulation mode and the original file modulation clock to generate original file data to be modulated; and the mapping module generates a complex modulation signal of the user-defined data file according to the data to be modulated of the original file and the data of the constellation diagram. The measuring device and the modulation method can save software resources and improve response time when the modulation source is a user-defined data file.
Description
Technical Field
The invention relates to the field of test and measurement, in particular to a measuring device capable of generating a user-defined data file quadrature amplitude modulation signal and a quadrature amplitude modulation method thereof.
Background
Quadrature Amplitude Modulation (QAM) is an efficient digital Modulation and demodulation method, and compared with other Modulation techniques, the Modulation technique can fully utilize bandwidth, has a very high frequency utilization rate, and has strong noise immunity. Therefore, the method is widely applied to the fields of medium and large-capacity digital microwave communication systems, cable television network high-speed data transmission, satellite communication and the like. QAM is a vector modulation, the baseband signal to be modulated is firstly mapped to a complex plane (constellation diagram) to form 2 paths of complex modulation signals a and b (corresponding to the real part and the imaginary part of the complex plane, namely the horizontal direction and the vertical direction), then the a and b are subjected to double-sideband modulation of carrier suppression, and the signals are respectively and correspondingly modulated on two mutually orthogonal carriers (coswt and sinwt); and then adds the two to form the QAM modulated signal.
Common modulation methods for QAM include MQAM (e.g., 4QAM, 8QAM, 16QAM, 64QAM, etc.) and multilevel PSK (e.g., QPSK, 8PSK, 16PSK, etc.), and multilevel PSK is also denoted by MQAM as a specific example of QAM. Each modulation mode has a respective constellation diagram. The number part M of the above-mentioned modulation scheme name indicates the number of coordinate points on the constellation diagram, for example, the number of coordinate points of 256QAM and 8PSK is 256 and 8, respectively, QPSK, that is, quadrature phase shift keying, and the number of coordinates thereof is 4. The process of converting the baseband signal to be modulated into 2 complex modulation signals a, b according to the constellation diagram is called "mapping".
The traditional quadrature amplitude modulation adopts an analog implementation mode, and because the consistency and the stability of analog devices are not ideal enough, the performance of the system is greatly influenced, and the functions of the analog system are single. With the rapid development of digital technology, quadrature amplitude modulation realized by a digital mode, especially by a mode of combining a programmable logic array (FPGA) and a CPU, has the advantages of high integration level, good flexibility and rich functions, and can conveniently modify a QAM modulation mode.
A method for generating a quadrature amplitude modulated signal is described in patent document entitled "method, device and digital signal generator for generating a quadrature amplitude modulated signal" with patent application number 201110431543.5. Referring to fig. 1, which is a schematic structural diagram of a QAM modulation control unit 1 disclosed in this patent document, the QAM modulation control unit 1 is used for mapping a modulation source into a complex modulation signal, and includes: the device comprises a control module 101, a modulation source selection module 102, a baseband rate control module 103, a modulation file memory 104, a memory controller 105, a pseudo-random sequence generation module 106 and an analog-to-digital conversion module 107.
When the modulation source is selected as an external analog source, the analog-to-digital conversion module 107 is configured to convert an externally input analog quantity of the mapped 2-channel complex modulation signal into a digital quantity, and then send the digital quantity to the modulation source selection module 102, and the modulation source selection module 102 selects and outputs the digital quantity according to the modulation source;
when the modulation source is selected as the pseudorandom sequence, the pseudorandom sequence generation module 106 is configured to map the pseudorandom sequence into a complex modulation signal according to a modulation mode set by a user, and send the complex modulation signal to the modulation source selection module 102, where the modulation modes are different, and sequence formats of data output by the pseudorandom sequence generation module 106 are also different accordingly, for example: when the modulation mode is 16QAM, the pseudo-random sequence generation module 106 sequentially circulates the first 2 bits of the pseudo-random sequence as one path a of the complex modulation signal and the second 2 bits as the other path b of the complex modulation signal; when the modulation mode is 64QAM, the pseudo-random sequence generation module 106 cycles the first 3 bits of the pseudo-random sequence as a and the second 3 bits as b in sequence, and finally generates a modulation signal to be sent to the modulation element selection module 102, and the modulation source selection module 102 selects and outputs the modulation signal according to the modulation source;
when the modulation source is selected as the custom data file, modulation file memory 104 and memory controller 105 are used to enable the storage and reading of the custom data file. Before QAM modulation starts, a central processing unit (not shown in fig. 1) of the system first writes a user-defined data file into a memory, then reads the user-defined data file from the memory according to a modulation mode set by a user, maps the user-defined data file into 2-channel complex modulation signals, and writes the complex modulation signals into a modulation file memory 104 through a control module 101 and a memory controller 105; when modulation is started, the memory controller 105 reads the 2-channel complex modulation signal from the modulation file memory 104 into the modulation source selection module 102, and the modulation source selection module 102 selects and outputs the modulation signal according to the modulation source.
From the above, there are two main technical problems in the prior art:
1. when the modulation source is selected as the pseudo-random sequence, the pseudo-random sequence generation module 106 maps the generated pseudo-random sequence, and the mapping principle is as follows: firstly, a serial pseudo-random sequence is generated, and then the first N/2 bits and the last N/2 bits of the serial code stream (pseudo-random sequence) are respectively used as complex modulation signals a and b according to different modulation modes. For 4QAM, 8QAM, 16QAM, 64QAM, 256QAM, 512QAM, QPSK, 8PSK, 16PSK, the N values are 2, 3, 4, 6, 8, 9, 2,3、4，M＝2N. Therefore, the method for generating the modulation signal in the prior art can only realize the modulation mode with the even number of N, but cannot realize the modulation modes with the odd number of N, such as 8QAM, 8PSK and the like.
2. When the modulation source is selected as the custom data file, the custom data file is mapped by the central processing unit, and the advantage is that the custom constellation diagram is supported. However, when the user reconfigures the user-defined data file or modifies the modulation scheme, the central processing unit needs to retrieve the self-defined data file from the memory again, and perform mapping processing on the data according to the modified modulation scheme. The central processing unit typically reads the non-volatile memory (e.g., Flash memory) at a slow rate and the central processing unit needs to map each value of the custom data file before writing to modulation file memory 104. The above-described process flow brings about the following problems: the processing time of reading, mapping and writing in the central processing unit is longer, so that the response time is slow when the modulation mode is modified or the user-defined data file is modified, and a large amount of resources of the central processing unit are occupied; moreover, when mapping a custom data file, for example, 8QAM, the numerical value of the custom data file with 3 bits is to be mapped to a complex modulation signal with 2 paths of higher data bit widths, and in order to ensure the accuracy of coordinates on a constellation diagram, the data bit width of the complex modulation signal is usually 16 bits, that is, 3 bits are to be amplified to 2 paths of 16 bits, which is amplified by nearly 10 times, that is, the capacity of a memory storing the 2 paths of complex modulation signals is 10 times of that of the custom data file, which obviously causes great resource waste.
Disclosure of Invention
In order to solve the second technical problem in the prior art, the invention provides a measuring device of a user-defined data file quadrature amplitude modulation signal and a modulation method thereof, which can reduce the processing time of a central processing unit and save the resources of the central processing unit.
The invention provides a measuring device capable of generating a user-defined data file quadrature amplitude modulation signal, which comprises a system control unit, a quadrature amplitude modulation unit and a quadrature amplitude control unit, wherein the system control unit generates a quadrature amplitude modulation mode, a quadrature amplitude modulation source, a baseband rate value, constellation map data, a carrier frequency, a user-defined data file or a sequence order according to user input setting; the quadrature amplitude control unit generates a complex modulation signal according to a quadrature amplitude modulation mode, a quadrature amplitude modulation source, a baseband rate value, constellation diagram data, a sequence order or a user-defined data file; the quadrature amplitude modulation unit generates a quadrature amplitude modulated signal according to the complex modulation signal and the carrier frequency; the quadrature amplitude control unit comprises a baseband rate control module, a storage control module, a bit width conversion module and a mapping module, when the quadrature amplitude modulation source is a user-defined data file, the baseband rate control module generates an original file baseband clock and an original file modulation clock according to a baseband rate value and a modulation mode; the storage control module generates original file baseband data according to the original file baseband clock and the custom data file; the bit width conversion module performs bit width conversion on the baseband data of the original file according to the modulation mode and the original file modulation clock to generate original file data to be modulated; and the mapping module generates a complex modulation signal of the user-defined data file according to the data to be modulated of the original file and the data of the constellation diagram.
In the measuring device of the present invention, the quadrature amplitude modulation unit may further include a pseudo random sequence generation module and a serial-to-parallel conversion module, and when the quadrature amplitude modulation source is a pseudo random sequence, the baseband rate control module generates a pseudo random sequence baseband clock and a pseudo random sequence modulation clock according to a baseband rate value and a modulation mode; the pseudo-random sequence generation module generates pseudo-random sequence serial data according to the pseudo-random sequence baseband clock and the sequence order; the serial-parallel conversion module carries out serial-parallel conversion on the pseudo-random sequence serial data according to the modulation mode and the pseudo-random sequence modulation clock to generate pseudo-random sequence data to be modulated; and the mapping module generates a pseudo-random sequence complex modulation signal according to the pseudo-random sequence data to be modulated and the constellation diagram data.
In the measuring device of the present invention, the mapping module may further include an address generating module, a constellation data storage module, and a complex modulation signal generating module, where the address generating module generates a mapping address according to a quadrature amplitude modulation source; the constellation diagram data storage module stores the constellation diagram data; the complex modulation signal generation module generates the complex modulation signal according to the quadrature amplitude modulation source, the mapping address and the constellation diagram data.
In the measuring device of the invention, when the quadrature amplitude modulation source is a user-defined data file, the address generating module selects the original file to-be-modulated data as the mapping address; the complex modulation signal generation module reads the constellation diagram data in the constellation storage module according to the mapping address and obtains the complex modulation signal of the user-defined data file according to the read data.
In the measuring device of the invention, when the quadrature amplitude modulation source is a pseudorandom sequence, the address generation module selects data to be modulated of the pseudorandom sequence as a mapping address; the complex modulation signal generation module reads the constellation diagram data in the constellation storage module according to the mapping address and obtains the pseudo-random sequence complex modulation signal according to the read data.
In the measuring device of the present invention, a ratio of the frequency value of the original file modulation clock to the frequency value of the original file baseband clock may be D: n, D is the bit width of each data of the user-defined data file, and the number of points on the constellation diagram corresponding to the modulation mode is 2N。
In the measuring device of the invention, the storage control module can also convert the self-defined data file into original file data according to a system communication protocol and store the original file data, and read the original file data according to an original file baseband clock to generate original file baseband data.
In the measuring device of the invention, the bit width conversion module can also convert the original file baseband data with D bits into original file to-be-modulated data with N bits according to the original file modulation clock, wherein D is the bit of each data of the user-defined data fileWide, the number of points on the constellation diagram corresponding to the modulation scheme is 2N。
In the measuring apparatus of the present invention, the qam unit may further be formed by an FPGA device.
The invention also provides a user-defined data file quadrature amplitude modulation method, which comprises the following steps:
1) generating a quadrature amplitude modulation mode, a quadrature amplitude modulation source, a baseband rate value, constellation data, a user-defined data file and a carrier frequency according to user input setting;
2) generating an original file baseband clock and an original file modulation clock according to the baseband rate value and the modulation mode;
3) generating original file baseband data according to the original file baseband clock and the custom data file;
4) performing bit width conversion on the baseband data of the original file according to the modulation mode and the original file modulation clock to generate original file data to be modulated;
5) generating a user-defined data file complex modulation signal according to original file data to be modulated and constellation diagram data;
6) and generating a modulated signal of the user-defined data file according to the modulated signal of the user-defined data file and the carrier frequency.
Compared with the prior art, when the user-defined data file is used as a modulation source, the measuring device and the quadrature amplitude modulation method do not need a system control unit to perform mapping processing when the user-defined data file is modified by performing bit width conversion on an original file and improving a mapping method of a constellation diagram, so that software processing resources are saved, and response time is shortened; the capacity of the memory for storing the original file is the length of the custom data file, and compared with the prior art for writing the modulated file memory of the mapped 2-path complex modulated signal, the capacity of the memory does not need extra memory capacity. But also the constellation data can be customized.
In addition, when the pseudo-random sequence is a modulation source, the method can support all modulation modes and can customize the constellation map by performing serial-parallel conversion on the pseudo-random sequence and improving the mapping method of the constellation map, so that the application range is wider and more flexible.
And when the user modifies the modulation mode or the constellation diagram, the invention only needs to reconfigure the modulation mode and writes the new constellation diagram coordinate data into the mapping memory, because the maximum length of the constellation diagram data is only 512, the writing time is shorter, and excessive software processing resources are not consumed.
Drawings
Fig. 1 is a schematic diagram of a QAM modulation control unit 1 in the prior art.
Fig. 2 is a schematic structural diagram of a measuring apparatus 2 capable of generating a quadrature amplitude modulation signal of a custom data file in the embodiment of the present invention.
Fig. 3 is a schematic structural diagram of the quadrature amplitude control unit 202 in the embodiment of the present invention.
Fig. 4 is a rectangular constellation of 16 QAM.
Fig. 5 is a concentric constellation of 16 QAM.
FIG. 6 is a flowchart of a method for quadrature amplitude modulation of a custom data file according to an embodiment of the present invention
Fig. 7 is a schematic structural diagram of the pseudo-random sequence generation module 302 in the embodiment of the present invention.
Fig. 8 is a flowchart of a quadrature amplitude modulation method for pseudo random sequences in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clear, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.
Fig. 2 is a schematic structural diagram of a measuring apparatus 2 capable of generating a quadrature amplitude modulation signal of a custom data file according to an embodiment of the present invention.
In the present embodiment, the measurement apparatus 2 includes a system control unit 201, a quadrature amplitude control unit 202, and a quadrature amplitude modulation unit 203.
The system control unit 201 is configured to generate a quadrature amplitude modulation mode, a quadrature amplitude modulation source, a baseband rate value, constellation data, a carrier frequency, and a sequence order or a custom data file according to user input settings.
In the present embodiment, the system control unit 201 includes an input unit, a clock unit, a storage unit and a central processing unit, wherein the input unit is used for receiving input settings of a user, the clock unit is used for generating a system working clock, the storage unit is used for storing various system parameters, measurement data and the like, the central processing unit is used for generating corresponding system parameters according to the input settings of the user and sending the system parameters to the quadrature amplitude modulation unit 202 and the quadrature amplitude modulation unit 203, before quadrature amplitude modulation, a user needs to select one of a pseudo-random sequence, a user-defined data file and an external analog source as a quadrature amplitude modulation source, then, according to the measurement requirement, the quadrature amplitude modulation mode, the baseband rate value, the constellation data, the carrier frequency, and the sequence order (set when the modulation source is a pseudorandom sequence) or the user-defined data file (set when the modulation source is the user-defined data file) are set.
The qam control unit 202 is configured to generate complex modulation signals a and b according to a qam scheme, a qam source, a baseband rate value, constellation data, and a sequence order or a custom data file.
The quadrature amplitude modulation unit 203 generates a quadrature amplitude modulated signal according to the complex modulation signals a and b and the carrier frequency;
in this embodiment, the quadrature amplitude modulation unit 203 includes a digital control oscillator 2031, a first multiplier 2032, a second multiplier 2033, an adder 2034, and an output unit 2035, the digital control oscillator 2031 outputs two mutually orthogonal co-frequency carriers cos ω t and sin ω t according to a carrier frequency, and respectively sends them to the first multiplier 2032 and the second multiplier 2032, the quadrature amplitude control unit 202 sends the generated complex modulation signals a and b respectively to the first multiplier 2032 and the second multiplier 2033, and after multiplying them with the carriers, adds them in the adder 2034, and finally obtains the digital quadrature amplitude modulation signal c: the output unit 2035 converts the digital quadrature amplitude modulated signal c into an analog quadrature amplitude modulated signal d, and outputs the analog quadrature amplitude modulated signal d.
The configuration of the quadrature amplitude control unit 202 and the workflow of generating the complex modulated signal in the present embodiment will be described in detail below.
Referring to fig. 3, it is a schematic structural diagram of the quadrature amplitude control unit 202 in the present embodiment.
As mentioned above, the system control unit 201 generates various parameters according to the user input setting, when the user sets the qam source to be a custom data file, the qam mode w1, the baseband rate value w2, the constellation data w3, and the custom data file w10 need to be set, and the system control unit 201 sends these parameters generated according to the user setting to each module in the qam unit 202, so as to generate the custom data file complex modulation signals a2 and b 2.
When the qam source is a custom data file, the baseband rate control module 301 generates an original file baseband clock w11 and an original file modulation clock w12 according to the baseband rate value w2 and the qam scheme w 1.
In this embodiment, the baseband rate control module 301 generates an original file baseband clock w11 according to a baseband rate value w2, and the frequency value of the original file baseband clock w11 generated by the baseband rate control module 301 is equal to the baseband rate value w 2; the baseband rate control module 301 further generates an original file modulation clock w12 according to the quadrature amplitude modulation scheme w1 and the baseband rate value w2, assuming that the quadrature amplitude modulation scheme w1 is represented by MQAM, and M is 2NThe number of coordinate points on the constellation corresponding to the QAM method is 2NThe frequency value of the original file modulation clock w12 generated by the baseband rate control module 301 is equal to the D/N of the original file baseband clock w11, so the frequency value of the original file modulation clock w12 is equal to the D/N of the baseband rate value w 2. D is the bit width of each datum in the custom data file.
The storage control module 305 generates original file baseband data w13 according to the original file baseband clock w11 and the custom data file w 10.
In this embodiment, the storage control module 305 performs format conversion on the custom data file w10 according to the system communication protocol of the measuring apparatus 2, converts the custom data file w10 into original file data, and stores the original file data, where the format conversion refers to converting the custom data file w10 into a format required by the system communication protocol, and does not involve mapping of data; when the system control unit 201 sends a signal for starting modulation, the storage control module 305 reads the original file data according to the frequency value of the original file baseband clock w11 to generate original file baseband data w 13.
In this embodiment, the system control unit 201 directly sends the custom data file w10 to the storage control module 305 without any processing, so that the data length of the original file data (the format-converted custom data file) stored by the storage control module 306 is the data length of the custom data file w10, and no additional storage space is needed, and the system control unit 201 does not need to perform complicated processing each time the custom data file w10 is modified, thereby saving software resources and increasing response time.
The bit width conversion module 306 performs bit width conversion on the original file baseband data w13 according to the quadrature amplitude modulation manner w1 and the original file modulation clock w12 to generate original file data to be modulated w 14.
In this embodiment, the bit width conversion module 306 performs bit width conversion on the original file baseband data w13 according to the QAM scheme w1 and the original file modulation clock w12, and converts the original file baseband data w13 with D (D is the bit width of each data in the custom data file) bits into parallel data with N bit width — the original file data to be modulated w14, for example, w1 is 8QAM, and then M is 2N，8＝23So that N is 3, the bit-width conversion module 306 converts the D-bit original file baseband data w13 into 3-bit original file to-be-modulated data w14 according to the original file modulation clock w 12. It can be seen that the rate of the original file baseband data w13 is obtained from the frequency of the original file baseband clock w11, the rate of the original file to-be-modulated data w14 is obtained from the frequency of the original file modulation clock w12, and as mentioned above, the ratio of the frequency values of the original file modulation clock w12 and the original file baseband clock w11 is D: n, so that the original file baseband number of D bits can be realizedAnd converting the data bit width between the data w13 and the original file to-be-modulated data w14 with the N bit width.
The mapping module 304 generates the complex modulation signals a2 and b2 of the custom data file according to the original file to-be-modulated data w14 and the constellation diagram data w 3.
In this embodiment, the mapping module 304 includes an address generating module, a constellation data storage module, and a complex modulation signal generating module. When the quadrature amplitude modulation source is a custom data file, the address generation module takes original file to-be-modulated data w14 as a mapping address; the constellation diagram data storage module stores constellation diagram data w3 input by a user, and the complex modulation signal generation module reads the constellation diagram data w3 in the constellation diagram storage module according to the mapping address and generates complex modulation signals a2 and b2 of the user-defined data file according to the read data.
In the present embodiment, the constellation data w3 input by the user may be standard or may be defined by the user. The following illustrates that the invention can realize the self-defined constellation diagram data and meet different requirements of users.
Referring to fig. 4, a rectangular constellation of 16 QAM. The rectangular constellation diagram of 16QAM has 16 coordinate points, the data of each coordinate point is respectively stored in a storage unit in the constellation diagram data storage module, and the addresses of the storage units are 0000 to 1111. When a user edits the constellation diagram data, the coordinate position (x, y) of each coordinate point on the constellation diagram can be defined, the complex modulation signal generation module takes the original file data to be modulated w14 as a mapping address, and the position data of each coordinate point on the coordinate system is taken out from each storage unit in the constellation diagram data storage module to generate original file complex modulation signals a2 and b 2.
For the constellation diagram edited by the user, the sequence of the coordinate points is actually the mapping address; and the specific position of the coordinate point is the constellation data w 3. It can be seen that a one-to-one mapping relationship is established between the mapping addresses and the constellation data w3 by the above method.
Each storage unit of the constellation diagram data storage module stores coordinate point coordinate data with 2P-bit widths (P is the bit width of the digital-to-analog converter), and high P bits and low P bits of the coordinate data read according to the mapping address are respectively used as a complex modulation signal a2 and b2 of the custom data file.
Referring again to fig. 5, it is a 16QAM concentric constellation diagram, which is also 16 coordinate points, but the user-defined constellation data w3 is different, that is, the coordinate positions of the coordinate points are different, so the custom data file modulation data a2 and b2 generated according to the above method are also different.
Therefore, by adopting the constellation map data mapping method, a user can self-define the constellation map data as required and generate a plurality of self-defined data file complex modulation signals, so that a plurality of quadrature amplitude modulation signals are generated and a plurality of measurement requirements are met.
Fig. 6 is a flowchart of a method for quadrature amplitude modulation of a custom data file in this embodiment, which includes the following steps:
step 601: generating a quadrature amplitude modulation mode w1, a quadrature amplitude modulation source, a baseband speed value w2, constellation diagram data w3, a custom data file w10 and a carrier frequency w4 according to user input setting;
step 602: generating an original file baseband clock w11 and an original file modulation clock w12 according to a baseband rate value w2 and a quadrature amplitude modulation mode w 1;
step 603: generating original file baseband data w13 according to an original file baseband clock w11 and a custom data file w 10;
step 604: according to a quadrature amplitude modulation mode w1 and an original file modulation clock w12, performing bit width conversion on original file baseband data w13 to generate original file data to be modulated w 14;
step 605: generating a complex modulation signal a2 and a complex modulation signal b2 of a custom data file according to original file data to be modulated w14 and constellation diagram data w 3;
step 606: the custom data file modulated signal is generated according to the custom data file modulated signals a2, b2 and carrier frequency w 4.
The specific implementation method of the quadrature amplitude modulation method for the custom data file can refer to the method for generating the custom data file modulated signal by the measuring device 2, and is not described herein again.
As another illustration of the present embodiment, the quadrature amplitude control unit 202 further includes a baseband rate control module 301, a pseudo-random sequence generation module 302, a serial-to-parallel conversion module 303, and a mapping module 304.
As mentioned above, the system control unit 201 generates various parameters to the quadrature amplitude control unit 202 according to the user input setting, when the user sets the quadrature amplitude modulation source to be the pseudo random sequence, the quadrature amplitude modulation manner w1, the baseband rate value w2, the constellation diagram data w3 and the sequence order w5 need to be set, and the system control unit 201 sends these parameters generated according to the user setting to each module in the quadrature amplitude control unit 202 for generating the pseudo random sequence complex modulation signals a1 and b 1.
When the qam source is a pseudo random sequence, the baseband rate control module 301 is configured to generate a pseudo random sequence baseband clock w6 and a pseudo random sequence modulation clock w7 according to the qam pattern w1 and the baseband rate value w 2.
In the embodiment, the baseband rate control module 301 generates a pseudo-random sequence baseband clock w6 according to a baseband rate value w2, and the frequency value of the pseudo-random sequence baseband clock w6 generated by the baseband rate control module 301 is equal to the baseband rate value w 2; the baseband rate control module 301 further generates a pseudo random sequence modulation clock w7 according to the quadrature amplitude modulation scheme w1 and the baseband rate value w2, assuming that the quadrature amplitude modulation scheme w1 is represented by MQAM, and M is 2NThe number of coordinate points on the constellation corresponding to the QAM method is 2NThe frequency value of the pseudo-random sequence modulation clock w7 generated by the baseband rate control module 301 is equal to 1/N of the pseudo-random sequence baseband clock w6, so the frequency value of the pseudo-random sequence modulation clock w7 is equal to 1/N of the baseband rate value w 2.
The pseudo-random sequence generation module 302 generates pseudo-random sequence serial data w8 according to the pseudo-random sequence baseband clock w6 and the sequence order w 5.
Referring to fig. 7, a schematic diagram of the structure of the pseudo-random sequence generation module 302 is shown. In the present embodiment, pseudo-randomThe sequence generation module 302 is composed of a maximal length linear feedback shift register, a w 5-order shift register composed of w5 registers, w5 is the sequence order of the pseudo-random sequence, and the output of each register is x under the control of the pseudo-random sequence baseband clock w60、x1…xw5-2、xw5-1The feedback unit 401 feeds back the result of formula 1 to the level 1 register. Wherein, CiCalled feedback coefficient, having a value of 0 or 1, the feedback coefficients being different, xw5-1Pseudo-random sequence serial data w8 of different sequence order is generated.
Equation 1
The serial-parallel conversion module 303 performs serial-parallel conversion on the pseudo-random sequence serial data w8 according to the quadrature amplitude modulation mode w1 and the pseudo-random sequence modulation clock w7 to generate pseudo-random sequence data to be modulated w 9.
In this embodiment, the serial-to-parallel conversion module 303 performs serial-to-parallel conversion on the pseudo-random sequence serial data w8 according to the quadrature amplitude modulation manner w1 and the pseudo-random sequence modulation clock w7, and converts the 1-bit pseudo-random sequence serial data into parallel data with N-bit width, i.e., the pseudo-random sequence data to be modulated w9, where w1 is 8QAM, and then M is 2N，8＝23So N is 3, the serial-to-parallel conversion module 303 converts the 1-bit pseudo-random sequence serial data into 3-bit pseudo-random sequence data to be modulated w9 according to the pseudo-random sequence modulation clock w 7. It can be seen that the rate of the pseudo-random sequence serial data w8 is obtained from the frequency of the pseudo-random sequence baseband clock w6, the rate of the pseudo-random sequence data to be modulated w9 is obtained from the frequency of the pseudo-random sequence modulation clock w7, and as mentioned above, the ratio of the frequency values of the pseudo-random sequence modulation clock w7 and the pseudo-random sequence baseband clock w6 is 1: n, therefore, data bit width conversion between the 1-bit pseudo random sequence serial data w8 and the N-bit pseudo random sequence tone data w9 can be realized.
The mapping module 304 generates pseudo-random sequence complex modulation signals a1 and b1 according to the pseudo-random sequence data w9 to be modulated and the constellation data w 3.
In this embodiment, the mapping module 304 includes an address generating module, a constellation data storage module, and a complex modulation signal generating module. When the quadrature amplitude modulation source is a pseudo-random sequence, the address generation module takes the pseudo-random sequence data to be modulated w9 as a mapping address; the constellation diagram data storage module stores constellation diagram data w3 input by a user, and the complex modulation signal generation module reads the constellation diagram data w3 in the constellation diagram storage module according to the mapping address and generates pseudo-random sequence complex modulation signals a1 and b1 according to the read data.
It can be seen that the present invention is achieved by performing 1: the serial-parallel conversion of N ensures that the data mapping processing is not limited by N being an odd number any more, the modulation mode of N being an odd number and N being an even number can be realized, and the application range is wider and more flexible.
In the present embodiment, the constellation data w3 input by the user may be standard or may be defined by the user. The following illustrates that the invention can realize the self-defined constellation diagram data and meet different requirements of users.
Referring to fig. 4, a rectangular constellation of 16 QAM. The rectangular constellation diagram of 16QAM has 16 coordinate points, the data of each coordinate point is respectively stored in a storage unit in the constellation diagram data storage module, and the addresses of the storage units are 0000 to 1111. When a user edits the constellation diagram data, the coordinate position (x, y) of each coordinate point on the constellation diagram can be defined, the complex modulation signal generation module takes the pseudo-random sequence data to be modulated w9 as a mapping address, and the position data of each coordinate point on the coordinate system is taken out from each storage unit in the constellation diagram data storage module to generate pseudo-random sequence complex modulation signals a1 and b 1.
For the constellation diagram edited by the user, the sequence of the coordinate points is actually the mapping address; and the specific position of the coordinate point is the constellation data w 3. It can be seen that a one-to-one mapping relationship is established between the mapping addresses and the constellation data w3 by the above method.
Each storage unit of the constellation diagram data storage module stores coordinate point coordinate data with 2P bit widths (P is the bit width of a digital-to-analog converter), and high P bits and low P bits of the coordinate data read according to a mapping address are respectively used as pseudo-random sequence complex modulation signals a1 and b 1.
Referring again to fig. 5, the 16QAM concentric constellation is also 16 coordinate points, but the user-defined constellation data w3 is different, that is, the coordinate positions of the respective coordinate points are different, so the pseudo random sequence modulation data a1 and b1 generated by the above method are also different.
Therefore, by adopting the constellation diagram data mapping method, a user can self-define the constellation diagram data as required and generate a plurality of pseudo-random sequence complex modulation signals, so that a plurality of quadrature amplitude modulation signals are generated and a plurality of measurement requirements are met.
Fig. 8 is a flowchart of a pseudo random sequence quadrature amplitude modulation method in this embodiment, which includes the following steps:
step 801: generating a quadrature amplitude modulation mode w1, a quadrature amplitude modulation source, a baseband rate value w2, constellation diagram data w3, a sequence order w5 and a carrier frequency w4 according to user input setting;
step 802: generating a pseudo-random sequence baseband clock w6 and a pseudo-random sequence modulation clock w7 according to a baseband rate value w2 and a quadrature amplitude modulation mode w 1;
step 803: generating pseudo-random sequence serial data w8 according to the pseudo-random sequence baseband clock w6 and the sequence order w 5;
step 804: according to a quadrature amplitude modulation mode w1 and a pseudo-random sequence modulation clock w7, serial-parallel conversion is carried out on pseudo-random sequence serial data w8 to generate pseudo-random sequence data to be modulated w 9;
step 805: generating pseudo-random sequence complex modulation signals a1 and b1 according to the pseudo-random sequence data w9 to be modulated and the constellation data w 3;
step 806: the pseudo-random sequence modulated signal is generated according to the pseudo-random sequence complex modulated signals a1 and b1 and the carrier frequency w 4.
For a specific implementation method, reference may be made to a method for generating a pseudo-random sequence modulated signal by the measurement apparatus 2, and details are not described here.
In the present embodiment, the quadrature amplitude control unit 202 is constituted by an FPGA device.
According to the measuring device and the quadrature amplitude modulation method capable of generating the quadrature amplitude modulation signal of the user-defined data file, bit width conversion is carried out on the original file, and the mapping method of the constellation diagram is improved, so that when the user-defined data file is modified, a system control unit is not needed to carry out mapping processing, software processing resources are saved, and response time is shortened; the capacity of the memory for storing the original file is the length of the custom data file, and compared with the prior art for writing the modulated file memory of the mapped 2-path complex modulated signal, the capacity of the memory does not need extra memory capacity. But also the constellation data can be customized.
In addition, when the pseudo-random sequence is used as a modulation source, the measuring device and the quadrature amplitude modulation method can support all modulation modes when the pseudo-random sequence is used as the modulation source by performing serial-parallel conversion on the pseudo-random sequence and improving the mapping method of the constellation diagram, and can also perform user-defined constellation diagram, so that the application range is wider and more flexible.
And when the user modifies the modulation mode or the constellation diagram, the invention only needs to reconfigure the modulation mode and writes the new constellation diagram coordinate data into the mapping memory, because the maximum length of the constellation diagram data is only 512, the writing time is shorter, and excessive software processing resources are not consumed.
Claims (10)
1. A measuring device capable of generating a user-defined data file quadrature amplitude modulation signal comprises a system control unit, a quadrature amplitude modulation unit and a quadrature amplitude control unit,
the system control unit generates an orthogonal amplitude modulation mode, an orthogonal amplitude modulation source, a baseband rate value, constellation data, a carrier frequency and a custom data file according to user input setting, or generates the orthogonal amplitude modulation mode, the orthogonal amplitude modulation source, the baseband rate value, the constellation data, the carrier frequency and a sequence order;
the quadrature amplitude control unit generates a complex modulation signal according to the quadrature amplitude modulation mode, the quadrature amplitude modulation source, the baseband rate value, the constellation diagram data and the sequence order, or according to the quadrature amplitude modulation mode, the quadrature amplitude modulation source, the baseband rate value, the constellation diagram data and the user-defined data file;
the quadrature amplitude modulation unit generates a quadrature amplitude modulated signal according to the complex modulation signal and the carrier frequency;
it is characterized in that the preparation method is characterized in that,
the quadrature amplitude control unit comprises a baseband rate control module, a storage control module, a bit width conversion module and a mapping module,
when the qam source is a custom data file,
the base band rate control module generates an original file base band clock and an original file modulation clock according to the base band rate value and the modulation mode;
the storage control module generates original file baseband data according to the original file baseband clock and the custom data file;
the bit width conversion module performs bit width conversion on the baseband data of the original file according to the modulation mode and the original file modulation clock to generate original file data to be modulated;
and the mapping module generates a complex modulation signal of the user-defined data file according to the data to be modulated of the original file and the data of the constellation diagram.
2. The measurement device according to claim 1, wherein the QAM unit further comprises a pseudo-random sequence generation module and a serial-to-parallel conversion module,
when the quadrature amplitude modulation source is a pseudo-random sequence,
the base band rate control module generates a pseudo-random sequence base band clock and a pseudo-random sequence modulation clock according to the base band rate value and the modulation mode;
the pseudo-random sequence generation module generates pseudo-random sequence serial data according to the pseudo-random sequence baseband clock and the sequence order;
the serial-parallel conversion module carries out serial-parallel conversion on the pseudo-random sequence serial data according to the modulation mode and the pseudo-random sequence modulation clock to generate pseudo-random sequence data to be modulated;
and the mapping module generates a pseudo-random sequence complex modulation signal according to the pseudo-random sequence data to be modulated and the constellation diagram data.
3. A measuring device according to claim 1 or 2,
the mapping module comprises an address generating module, a constellation diagram data storage module and a complex modulation signal generating module,
the address generation module generates a mapping address according to the quadrature amplitude modulation source;
the constellation diagram data storage module stores the constellation diagram data;
the complex modulation signal generation module generates the complex modulation signal according to the quadrature amplitude modulation source, the mapping address and the constellation diagram data.
4. A measuring device according to claim 3,
when the qam source is a custom data file,
the address generation module selects original file data to be modulated as a mapping address;
the complex modulation signal generation module reads the constellation diagram data in the constellation diagram data storage module according to the mapping address, and obtains the complex modulation signal of the user-defined data file according to the read data.
5. A measuring device according to claim 3,
when the quadrature amplitude modulation source is a pseudo-random sequence,
the address generation module selects pseudo-random sequence data to be modulated as a mapping address;
the complex modulation signal generation module reads the constellation diagram data in the constellation diagram data storage module according to the mapping address, and obtains the pseudo-random sequence complex modulation signal according to the read data.
6. The measuring device of claim 1,
the ratio of the frequency value of the original file modulation clock to the frequency value of the original file baseband clock is D: n and D are bit width of each data of the user-defined data file, and the number of coordinate points on the constellation diagram corresponding to the modulation mode is 2N。
7. The measuring device of claim 1,
and the storage control module converts the user-defined data file into original file data according to a system communication protocol and stores the original file data, and reads the original file data according to an original file baseband clock to generate original file baseband data.
8. The measuring device of claim 1,
the bit width conversion module converts D bits of original file baseband data into N bits of original file to-be-modulated data according to an original file modulation clock, D is the bit width of each data of the user-defined data file, and the number of coordinate points on a constellation diagram corresponding to a modulation mode is 2N。
9. A measuring device according to claim 1 or 2,
the quadrature amplitude modulation unit is composed of FPGA devices.
10. A quadrature amplitude modulation method for a user-defined data file is characterized by comprising the following steps:
1) generating a quadrature amplitude modulation mode, a quadrature amplitude modulation source, a baseband rate value, constellation data, a user-defined data file and a carrier frequency according to user input setting;
2) generating an original file baseband clock and an original file modulation clock according to the baseband rate value and the modulation mode;
3) generating original file baseband data according to the original file baseband clock and the custom data file;
4) performing bit width conversion on the baseband data of the original file according to the modulation mode and the original file modulation clock to generate original file data to be modulated;
5) generating a user-defined data file complex modulation signal according to original file data to be modulated and constellation diagram data;
6) and generating a modulated signal of the user-defined data file according to the modulated signal of the user-defined data file and the carrier frequency.
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