Digital receiver signal demodulation method, system and device and storage medium

Abstract

The invention discloses a digital receiver signal demodulation method, system and device and a storage medium, and relates to the technical field of communication software radio, and the method comprises the steps: obtaining a complex signal, and judging the quadrant of the complex signal on a coordinate system; rotating the complex signal to a first quadrant of a coordinate system according to absolute values of a real part and an imaginary part of the complex signal; determining the rotation angle and the number of iterations of the complex signal; the complex signal is subjected to multiple times of iterative rotation according to a specific rotation angle until the last iteration result is close to a real axis, and the complex signal and the iterated phase of the complex signal are output; performing error compensation on the real part of the output complex signal to serve as the amplitude of the output complex signal, and restoring the iterated phase according to the quadrant to which the initial complex signal belongs to serve as the phase of the output complex signal; according to the method, a pipeline structure is adopted according to the iteration characteristics, the data throughput is increased, and the data operation efficiency is improved. And partial operation is replaced by adopting a table look-up form, so that the resource overhead is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of communication software radio, and in particular to a digital receiver signal demodulation method, system, equipment and storage medium. Background Art

[0002] In a digital receiver, it is often necessary to calculate the amplitude and phase of the received digital signal in order to complete demodulation and analysis of the digital signal.

[0003] The existing amplitude calculation is to transfer the original signal from the FPGA hardware to the software system through the software and hardware collaborative technology, and realize it by the existing square, square root and trigonometric operations in the high-level programming language, or directly realize the square and square root operations in the FPGA by DSP operation; both solutions have considerable defects. The former will occupy a large amount of communication resources between the hardware and software in the system, and when the signal sampling rate is very high, too frequent amplitude calculation will also bring a huge workload to the processor in the software system; the latter occupies a large amount of hardware resources and has poor flexibility. Once the bit width of the input signal changes, it is necessary to rewrite the program for the amplitude calculation function, which wastes a lot of development time. The algorithm designed in the present invention can adapt to the new signal bit width by directly changing the parameter configuration in the top layer of the module. At the same time, the use of a large amount of DSP resources will also cause a sharp increase in system operation power consumption, which is not conducive to the realization of low-power design of the system.

[0004] However, the amplitude calculation methods currently used will occupy a large amount of communication resources between hardware and software, and it is difficult to provide stable input for subsequent digital signal demodulation, resulting in low signal demodulation accuracy. Summary of the invention

[0005] In view of the shortcomings of the prior art in that more important resources such as DSP and BRAM are consumed in the process of digital signal processing, and the calculation results are of low accuracy, the present invention proposes a digital receiver signal demodulation method, system, device and storage medium, which solves the problems of the prior art by iteratively approximating the phase and amplitude by rotating the input complex signal by a specific angle multiple times.

[0006] A digital receiver signal demodulation method comprises the following steps:

[0007] Collecting digital signals received by a digital receiver and converting the digital signals into complex signals;

[0008] Calculate the amplitude and phase of complex signals;

[0009] The amplification factor of the front-end amplifier of the digital receiver is controlled by the amplitude and phase of the complex signal, the amplified complex signal is input into the signal processing unit of the digital receiver, and the baseband digital signal is obtained by demodulation;

[0010] The step of calculating the amplitude and phase of the complex signal specifically includes the following steps:

[0011] Determine the quadrant to which the complex signal belongs in the xy coordinate system;

[0012] According to the absolute values ​​of the real part and the imaginary part of the complex signal, the complex signal is rotated to the first quadrant of the xy coordinate system, and the largest one of the real part and the imaginary part is exchanged with the real part;

[0013] Determine the rotation angle and iteration number of the complex signal according to the CORDIC iterative rotation angle table; iterate the complex signal multiple times according to the specific rotation angle until the last iteration result approaches the real axis, and then output the complex signal and its iterative phase;

[0014] The real part of the output complex signal is error compensated and used as the amplitude of the output complex signal, and the iterative phase is restored according to the quadrant to which the initial complex signal belongs and used as the phase of the output complex signal.

[0015] Furthermore, the determining of the quadrant to which the input complex signal belongs in the xy coordinate system is performed by determining the quadrant to which the complex signal belongs according to the difference in magnitudes of the real part and the imaginary part of the complex signal.

[0016] Furthermore, the calculation formula for the real part and the imaginary part of the output complex signal is:

[0017] x i+1 =x i -y i tanθ

[0018] y i+1 =y i +x i tanθ

[0019] Among them, x i Represents the value of the real part at the i-th iteration, y i represents the value of the imaginary part at the i-th iteration, x i+1 Represents the value of the real part at the i+1th iteration, y i+1 Represents the value of the real part at the i+1th iteration; θ represents the rotation angle, and the positive or negative value of θ represents the direction of rotation.

[0020] Furthermore, the complex signal is rotated to the first quadrant of the xy coordinate system based on the absolute values ​​of the real and imaginary parts of the complex signal. Specifically, the coordinates of the point where the complex signal is located at the end of the coordinate system are selected, and the absolute values ​​of the horizontal and vertical coordinates of the point are taken at the same time to convert the coordinates of the point into positive numbers, thereby rotating the complex signal to the first quadrant of the xy coordinate system.

[0021] Furthermore, the real part of the output complex signal is approximately equal to the approximate value of the signal amplitude, and the amplitude of the output complex signal is obtained by multiplying the approximate value of the signal amplitude by a compensation coefficient.

[0022] The present invention also includes a digital receiver signal demodulation system, comprising:

[0023] An acquisition module, used for acquiring digital signals received by a digital receiver and converting the digital signals into complex signals;

[0024] A calculation module, used for calculating the amplitude and phase of the complex signal;

[0025] A demodulation module is used to control the gain of the front-end amplifier of the digital receiver through the amplitude and phase of the complex signal, input the amplified complex signal into the signal processing unit of the digital receiver, and demodulate to obtain a baseband digital signal;

[0026] Wherein, the calculation module includes:

[0027] A determination unit, used for determining the quadrant to which the input complex signal belongs in the xy coordinate system;

[0028] A rotation unit, for rotating the complex signal to the first quadrant of the xy coordinate system according to the absolute values ​​of the real part and the imaginary part of the complex signal, and exchanging the largest one of the real part and the imaginary part to the real part;

[0029] The iterative rotation unit is used to determine the rotation angle and iteration number of the complex signal according to the CORDIC iterative rotation angle table; the complex signal is iteratively rotated multiple times according to the specific rotation angle until the last iteration result approaches the real axis, and then the complex signal and its iterative phase are output;

[0030] The amplitude and phase output unit is used to perform error compensation on the real part of the output complex signal as the amplitude of the output complex signal, and restore the iterated phase according to the quadrant to which the initial complex signal belongs as the phase of the output complex signal.

[0031] The present invention also includes a digital receiver signal demodulation computer device, including: a memory, a processor and a computer program stored in the memory, and the processor implements the steps of the digital receiver signal demodulation method when executing the computer program.

[0032] The present invention also includes a readable storage medium, wherein the readable storage medium stores a computer program, wherein the computer program includes program instructions, and when the program instructions are executed by a processor, the steps of the digital receiver signal demodulation method are executed.

[0033] The present invention provides a digital receiver signal demodulation method, system, device and storage medium, which have the following beneficial effects:

[0034] The present invention uses the CORDIC algorithm to calculate the amplitude and phase of the input complex signal, and replaces the original complex square, square root and trigonometric function operations with simple addition and shift calculations, so that it can be implemented in FPGA. At the same time, according to its iterative characteristics, a pipeline structure is adopted to increase the data throughput and improve the data operation efficiency. The table lookup form is used to replace part of the operation, saving resource overhead; the input complex signal is rotated by a specific angle for multiple times to iteratively approximate to obtain the phase and amplitude. Compared with directly calling the IP core, the calculation method consumes fewer important resources such as DSP and BRAM, and the calculation result is more accurate; the front-end amplifier of the digital receiver is controlled according to the amplitude and phase of the input complex signal, and the amplitude of the signal is closed-loop controlled, which can stabilize the amplitude of the digital signal to provide a stable input for the subsequent demodulation algorithm, improve the accuracy of signal demodulation, and reduce the hardware resource consumption of the digital receiver while ensuring the same demodulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the CORDIC algorithm vector rotation in the present invention specification;

[0036] Figure 2 It is a case structure block diagram in an embodiment of the present invention;

[0037] Figure 3 A quadrant division diagram of a preprocessing module in an embodiment of the present invention;

[0038] Figure 4 Schematic diagram of USB signal demodulation output in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0040] The Coordinate Rotation Digital Computer (CORDIC) algorithm was first proposed by JD Volder1 in 1959 and was originally used in navigation systems. The algorithm rotates a specific angle multiple times, such as Figure 1 As shown, simple shifts and additions are used instead of multiplications, so that the calculation of vector rotation and orientation no longer requires complex calculations such as trigonometric functions, multiplication, and square root. Because of the iterative nature of CORDIC itself, it is also very suitable for pipeline form, which greatly improves the data throughput. Therefore, the CORDIC algorithm is very suitable for hardware implementation on FPGA.

[0041] The present invention proposes a digital receiver signal demodulation method, which uses the CORDIC algorithm to calculate the amplitude and phase of the input complex signal, and replaces the original complex square, square root and trigonometric function operations with simple addition and shift calculations, so that it can be implemented in FPGA, and specifically includes the following steps:

[0042] Step 1: Preprocess the input signal IQ of the digital receiver, and rotate the input complex signal to the first quadrant by taking the absolute value method (select the coordinates of the point where the complex signal is located at the end of the coordinate system, take the absolute values ​​of the horizontal and vertical coordinates of the point at the same time to convert the coordinates of the point into positive numbers, thereby rotating the complex signal to the first quadrant of the xy coordinate system), and ensure that the complex signal is located in the lower half of the first quadrant by exchanging the larger number to the real part to facilitate subsequent calculations.

[0043] Step 2: In the process of obtaining the absolute value and exchanging the imaginary and real parts, the quadrant position of the original signal is inferred according to the process, and the quadrant position is recorded and sent to the subsequent processing module together with the data. The quadrant information can be used for subsequent phase recovery.

[0044] Step 3: In the iterative calculation module, the direction of the rotation is determined according to the positive or negative of the imaginary part of the input signal, that is, the positive or negative of θ. After determination, according to the formula x i+1 =x i -y i tanθ and y i+1 =y i +x i tanθ calculates the real and imaginary parts of the complex signal after rotation. Because the rotation angle has a special value, this step can use shift operations instead of multiplication and trigonometric operations.

[0045] Step 4: While calculating the real and imaginary parts of the complex signal after rotation, the phase change caused by the rotation is recorded by looking up Table 1 according to the direction of rotation and the number of iterations, and is transmitted to the next stage together with the complex signal.

[0046] Table 1 Iterative rotation angle table

[0047]

[0048] Step 5: Repeat steps 3 and 4 according to the preset angle table until the accuracy of the iterative result meets the design requirements.

[0049] Step 6: The real part of the last stage output signal is error compensated and output as the amplitude. The phase of the last stage output is restored according to the rotation information recorded in the preprocessing and output as the phase (in the preprocessing process, all input vectors are rotated to the lower half of the first quadrant by taking the absolute value and exchanging the larger one to the real part. The finally calculated phase is not the true value, and the phase needs to be restored according to the original phase information recorded by the preprocessing module before rotation).

[0050] First, the number of CORDIC algorithm iterations is determined according to the system requirements and the CORDIC iteration rotation angle table (Table 1). In this case, 15 iterations are selected. The overall structure diagram of this case is shown in the figure. Figure 2 As shown in the figure, after the input complex signal is sent to the CORDIC module, the quadrant to which the input signal belongs is determined based on the difference in the real part and the imaginary part, as shown in the figure. Figure 3 After recording this information, take the absolute value of both the real and imaginary parts and swap the larger value to the real part, so that the input complex signal is rotated to Figure 3 The processed data and the recorded phase information are simultaneously sent to the subsequent iteration module.

[0051] In the iteration module, each stage rotates the corresponding angle in accordance with the rotation angle given in Table 1. When the input vector is in region 0, it rotates clockwise, and when it is in region 7, it rotates counterclockwise. The final iteration goal is to make the output complex signal as close to the real axis as possible. After determining the rotation direction, the phase change caused by the iteration of this stage is recorded by using a table lookup method.

[0052] After repeating the iteration module fifteen times, the result of the last iteration is very close to the real axis, so it can be approximately considered that the real part of the complex signal output is the amplitude of the signal. At the same time, the phase before the iteration can also be inferred from the phase change recorded in the iteration.

[0053] Since the amplitude of the complex signal is approximated during the rotation process, it needs to be multiplied by a compensation coefficient to obtain the true input signal amplitude. At the same time, the phase also needs to be restored according to the area information recorded in the pre-processing module before output.

[0054] The simulation effect of the present invention is as follows Figure 4 As shown, when a single tone signal is input, the output phase presents an oblique triangle wave, and the period is the same as the input signal. The output amplitude fluctuates only in a small range and remains basically stable. The output result is in line with expectations.

[0055] Based on the same inventive concept, the present invention also proposes a digital receiver signal demodulation system, comprising:

[0056] The acquisition module is used to acquire the digital signal received by the digital receiver and convert the digital signal into a complex signal.

[0057] The calculation module is used to calculate the amplitude and phase of the complex signal.

[0058] The demodulation module is used to control the gain of the front-end amplifier of the digital receiver through the amplitude and phase of the complex signal, input the amplified complex signal into the signal processing unit of the digital receiver, and demodulate to obtain the baseband digital signal.

[0059] The calculation module includes:

[0060] The judging unit is used to judge the quadrant to which the input complex signal belongs in the xy coordinate system.

[0061] The rotation unit is used to rotate the complex signal to the first quadrant of the xy coordinate system according to the absolute values ​​of the real part and the imaginary part of the complex signal, and to exchange the largest one of the real part and the imaginary part with the real part.

[0062] The iterative rotation unit is used to determine the rotation angle and the number of iterations of the complex signal according to the CORDIC iterative rotation angle table; the complex signal is iteratively rotated multiple times according to the specific rotation angle until the last iteration result approaches the real axis, and then the complex signal and its iterative phase are output.

[0063] The amplitude and phase output unit is used to perform error compensation on the real part of the output complex signal as the amplitude of the output complex signal, and restore the iterated phase according to the quadrant to which the initial complex signal belongs as the phase of the output complex signal.

[0064] Based on the same inventive concept, the present invention also proposes a digital receiver signal demodulation computer device, comprising: a memory, a processor and a computer program stored in the memory, and the processor implements the steps of the digital receiver signal demodulation method when executing the computer program.

[0065] Based on the same inventive concept, the present invention also proposes a readable storage medium, which stores a computer program. The computer program includes program instructions. When the program instructions are executed by a processor, they are used to execute the steps of the digital receiver signal demodulation method.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A digital receiver signal demodulation method, characterized in that: The following steps are involved: Collecting digital signals received by a digital receiver and converting the digital signals into complex signals; Calculate the amplitude and phase of complex signals; The amplification factor of the front-end amplifier of the digital receiver is controlled by the amplitude and phase of the complex signal, the amplified complex signal is input into the signal processing unit of the digital receiver, and the baseband digital signal is obtained by demodulation; The step of calculating the amplitude and phase of the complex signal specifically includes the following steps: Determine the quadrant to which the complex signal belongs in the xy coordinate system; According to the absolute values ​​of the real part and the imaginary part of the complex signal, the complex signal is rotated to the first quadrant of the xy coordinate system, and the largest one of the real part and the imaginary part is exchanged with the real part; Determine the rotation angle and iteration number of the complex signal according to the CORDIC iterative rotation angle table; iterate the complex signal multiple times according to the specific rotation angle until the last iteration result approaches the real axis, and then output the complex signal and its iterative phase; The real part of the output complex signal is error compensated and used as the amplitude of the output complex signal, and the iterative phase is restored according to the quadrant to which the initial complex signal belongs and used as the phase of the output complex signal.

2. A digital receiver signal demodulation method according to claim 1, characterized in that: The determining of the quadrant to which the input complex signal belongs on the xy coordinate system is performed by determining the quadrant to which the complex signal belongs according to the difference in magnitude between the real part and the imaginary part of the complex signal.

3. A digital receiver signal demodulation method according to claim 1, characterized in that: The calculation formula for the real part and imaginary part of the output complex signal is: x i+1 =x i -y i tanθ and i+1 =and i +x i tanθ Among them, x i Represents the value of the real part at the i-th iteration, y i represents the value of the imaginary part at the i-th iteration, x i+1 Represents the value of the real part at the i+1th iteration, y i+1 Represents the value of the real part at the i+1th iteration; θ represents the rotation angle, and the positive or negative value of θ represents the direction of rotation.

4. A digital receiver signal demodulation method according to claim 1, characterized in that: The complex signal is rotated to the first quadrant of the xy coordinate system based on the absolute values ​​of the real and imaginary parts of the complex signal. Specifically, the coordinates of the point where the complex signal is located at the end of the coordinate system are selected, and the absolute values ​​of the horizontal and vertical coordinates of the point are taken at the same time to convert the coordinates of the point into positive numbers, thereby rotating the complex signal to the first quadrant of the xy coordinate system.

5. A digital receiver signal demodulation method according to claim 1, characterized in that: The real part of the output complex signal is approximately the approximate value of the signal amplitude, and the amplitude of the output complex signal is obtained by multiplying the approximate value of the signal amplitude by the compensation coefficient.

6. A digital receiver signal demodulation system, characterized in that: include: An acquisition module, used for acquiring digital signals received by a digital receiver and converting the digital signals into complex signals; A calculation module, used for calculating the amplitude and phase of the complex signal; A demodulation module is used to control the gain of the front-end amplifier of the digital receiver through the amplitude and phase of the complex signal, input the amplified complex signal into the signal processing unit of the digital receiver, and demodulate to obtain a baseband digital signal; Wherein, the calculation module includes: A determination unit, used for determining the quadrant to which the input complex signal belongs in the xy coordinate system; A rotation unit, for rotating the complex signal to the first quadrant of the xy coordinate system according to the absolute values ​​of the real part and the imaginary part of the complex signal, and exchanging the largest one of the real part and the imaginary part to the real part; The iterative rotation unit is used to determine the rotation angle and iteration number of the complex signal according to the CORDIC iterative rotation angle table; the complex signal is iteratively rotated multiple times according to the specific rotation angle until the last iteration result approaches the real axis, and then the complex signal and its iterative phase are output; The amplitude and phase output unit is used to perform error compensation on the real part of the output complex signal as the amplitude of the output complex signal, and restore the iterated phase according to the quadrant to which the initial complex signal belongs as the phase of the output complex signal.

7. A digital receiver signal demodulation computer device, characterized in that: include: A memory, a processor and a computer program stored in the memory, wherein the processor implements the steps of the digital receiver signal demodulation method according to any one of claims 1 to 5 when executing the computer program.

8. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and the computer program includes program instructions. When the program instructions are executed by a processor, they are used to execute the steps of the digital receiver signal demodulation method according to any one of claims 1 to 5.

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