Self-adaptive baseband signal recovery method and system

Abstract

The invention discloses a self-adaptive baseband signal recovery method and system, and the method comprises the steps: carrying out the digital processing of a radio frequency signal subjected to frequency reduction processing, and obtaining a baseband signal with Doppler frequency shift; obtaining an in-phase signal and an orthogonal signal after real-time IQ decomposition; performing four-path parallel calculation to obtain four sub-signals, and transmitting the four sub-signals to a signal classifier through corresponding signal transmission channels; acquiring a Doppler phase at the current moment, determining a sub-signal transmitted at the current moment according to the Doppler phase, controlling the signal classifier to switch to a corresponding signal transmission channel according to the sub-signal transmitted at the current moment, and calculating an amplitude correction coefficient according to the Doppler phase; the sub-signals transmitted at the current moment are obtained through the signal classifier, the sub-signals are corrected through the amplitude correction coefficient, the recovered baseband signals are obtained, and the method is easy to implement, small in calculated amount, high in real-time performance and suitable for various signal systems with low time delay requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite communication signal processing, and in particular to an adaptive baseband signal recovery method and system. Background Art

[0002] With the increasing demand for despreading of satellite communication systems and signal processing of two-phase coded pulse compression radar, two-phase coded signals are widely used in pulse compression radar systems and satellite navigation communications due to their excellent range resolution in scenarios where high-speed target signals bring about large Doppler frequency shifts. In a single signal cycle, in-phase and orthogonal signals are extracted in real time, and four sub-chips are calculated. The original signal is restored by combining the timing relationship between the chips. This method is simple to implement, has a small amount of calculation, and requires few resources.

[0003] On the other hand, due to the high sensitivity of digital modulation signals to Doppler frequency shift, it also brings about the difficulty of carrier capture and the difficulty of despreading algorithm in scenarios with large Doppler frequency shift. At present, the methods to solve these problems revolve around the estimation of the carrier, including frequency scanning phase lock capture method, adaptive least squares method and maximum likelihood estimation method. These methods require pre-compensation or real-time search of carrier frequency, resulting in the following disadvantages: long capture time, difficult algorithm, high resource consumption and large processing delay. Summary of the invention

[0004] The object of the present invention is to provide an adaptive baseband signal recovery method, which can adaptively remove the Doppler frequency shift and restore the baseband signal in real time within each cycle time, has small calculation amount, good real-time performance and processing delay, and consumes less resources, and can be well applied to despreading and communication work in large Doppler frequency shift scenarios.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] On the one hand, the present application provides an adaptive baseband signal recovery system, comprising:

[0007] The A / D sampling module is used to digitize the acquired down-converted RF signal to obtain a baseband signal with Doppler frequency shift;

[0008] The orthogonal decomposition module is used to perform real-time IQ decomposition of the baseband signal with Doppler frequency shift to obtain an in-phase signal I and an orthogonal signal Q;

[0009] A real-time IQ decomposition module includes four sub-signal calculation modules for performing four-way parallel calculations on the in-phase signal I and the orthogonal signal Q to obtain four sub-signals, which are respectively transmitted to the signal selector through corresponding signal transmission channels;

[0010] The parameter calculation module is used to determine the sub-signal transmitted at the current moment according to the Doppler phase at the current moment, and generate a control signal of the signal sorter and send it to the signal sorter, and at the same time calculate the amplitude correction coefficient according to the Doppler phase at the current moment and send it to the amplitude correction module;

[0011] A signal selector, used to switch to the signal transmission channel corresponding to the sub-signal currently being transmitted according to the control signal, and transmit the sub-signal currently being transmitted to the amplitude correction module;

[0012] The amplitude correction module is used to correct the currently transmitted sub-signal according to the amplitude correction coefficient to obtain a restored baseband signal.

[0013] In some specific implementations, the digital processing includes:

[0014] After A / D sampling of the RF signal, a sampling signal is obtained; the sampling signal is quantized into a digital signal; and at the same time, the digital signal is down-converted in the digital domain using the signal generated by the DDS to obtain a baseband signal with Doppler frequency shift.

[0015] In some specific implementation schemes, the CORDIC algorithm is used in the orthogonal decomposition module to perform real-time IQ decomposition of the baseband signal with Doppler frequency shift to obtain the in-phase signal and the in-phase signal I and the orthogonal signal Q, where the I-path signal is I=sin(x+θ), the Q-path signal is Q=cos(x+θ), θ represents the phase modulation information, x represents the phase difference between the transmitted and received signals, and the frequency value of x is the Doppler frequency shift.

[0016] In some specific implementations, the four sub-signal calculation modules respectively perform the following calculation process to obtain four sub-signals:

[0017] Sig 1 =I+Q=sin(x+θ)+cos(x+θ)=sin(x+θ+0.25π)

[0018] Sig 2 =IQ=sin(x+θ)-cos(x+θ)=sin(x+θ-0.25π)

[0019] Sig 3 =-IQ=-sin(x+θ)-cos(x+θ)=sin(x+θ-0.75π)

[0020] Sig 4 =QI=cos(x+θ)-sin(x+θ)=sin(x+θ-1.25π);

[0021] In some specific implementations, the parameter calculation module obtains the Doppler phase at the current moment The calculation process is:

[0022]

[0023] in, Indicates the preset initial phase, ft indicates the current moment, and unwrap indicates The calculated phase is subjected to unwrapping calculation.

[0024] In some specific implementation schemes, the parameter calculation module pre-stores the numbers of each signal transmission channel in the real-time IQ decomposition module and the quadrants corresponding to the sub-signals transmitted by each signal transmission channel. The process of determining the sub-signal transmitted at the current moment is:

[0025] Determine the quadrant position of the Doppler phase at the current moment according to the Doppler phase at the current moment, and determine the number of the signal transmission channel according to the comparison between the quadrant position and the quadrant corresponding to each sub-signal channel;

[0026] A control signal is generated according to the number of the signal transmission channel to control the signal selector to switch to the corresponding signal transmission channel.

[0027] In some specific implementations, the amplitude correction coefficient A C The calculation process is:

[0028]

[0029] Among them, abs represents the absolute value function.

[0030] In a second aspect, the present application provides an adaptive baseband signal recovery method, which specifically includes the following steps:

[0031] S1, obtaining a down-converted radio frequency signal, and digitizing the radio frequency signal to obtain a baseband signal with a Doppler frequency shift;

[0032] S2, performing real-time IQ decomposition on the baseband signal with Doppler frequency shift to obtain an in-phase signal and an orthogonal signal;

[0033] S3, perform four-way parallel calculation on the in-phase signal and the orthogonal signal to obtain four sub-signals and transmit them to the signal selector through their corresponding signal transmission channels respectively;

[0034] S4, obtaining the Doppler phase at the current moment, determining the sub-signal transmitted at the current moment according to the Doppler phase, and controlling the signal sorter to switch to the corresponding signal transmission channel according to the sub-signal transmitted at the current moment, and calculating the amplitude correction coefficient according to the Doppler phase;

[0035] S5. Obtain the sub-signal currently transmitted through the signal selector, and correct the sub-signal using the amplitude correction coefficient to obtain a restored baseband signal.

[0036] In some specific implementations, the parameter calculation module obtains the Doppler phase at the current moment The calculation process is:

[0037]

[0038] in, Indicates the preset initial phase, ft indicates the current moment, and unwrap indicates The calculated phase is subjected to unwrapping calculation.

[0039] In some specific implementations, the amplitude correction coefficient A C The calculation process is:

[0040]

[0041] Among them, abs represents the absolute value function.

[0042] The inventive concept of the present invention is:

[0043] Currently, the problems of difficult carrier capture and demodulation algorithms in the scenario of Doppler frequency shift mostly revolve around the estimation of the carrier. This process requires pre-compensation or real-time search of the carrier frequency, which leads to problems such as long capture time, difficult algorithms, high resource consumption, and large processing delays.

[0044] In view of this, the present application proposes a system that does not require pre-compensation and search for carriers, does not require estimation of carriers, and does not use other devices such as discriminators or phase-locked loops to assist. In the scenario where a high-speed target signal brings a large Doppler frequency shift, in a single signal cycle, after the A / D processing is completed, a field programmable gate array is used to complete the use of a digital down-conversion module in the digital domain to obtain a baseband signal with Doppler frequency shift; then, through the orthogonal decomposition module, an in-phase signal I and an orthogonal signal Q are obtained; then, in the real-time IQ decomposition module, four sub-signals are calculated; finally, through the parameter calculation module, the quadrant where the current Doppler phase is located is obtained, and the current corresponding sub-signal is correctly output through the four-selection module. After amplitude correction, the baseband signal with the Doppler frequency shift removed can be obtained at the output port. The method is simple to implement, has a small amount of calculation, and is implemented through a field programmable gate array (FPGA), has strong real-time performance, and is suitable for various signal systems requiring low latency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A block diagram of an adaptive baseband signal recovery system provided by an embodiment of the present invention;

[0046] Figure 2 It is a time domain schematic diagram of the baseband signal when there is no Doppler frequency shift;

[0047] Figure 3 Schematic diagram of baseband signal demodulation measurement results when there is no Doppler frequency shift, where (a) represents the measurement time diagram, (b) represents the spectrum diagram, and (c) represents the output result diagram;

[0048] Figure 4 It is the time domain waveform diagram of the echo signal with Doppler frequency shift;

[0049] Figure 5 The demodulation test diagram of the baseband signal with Doppler frequency shift, where (a) is the measurement time diagram, (b) is the spectrum diagram, and (c) is the output result diagram;

[0050] Figure 6 A schematic diagram of time domain test results of four sub-signals in a sub-signal calculation module provided in an embodiment of the present invention; wherein (a) is a schematic diagram of a time domain test result of sig1, (b) is a schematic diagram of a time domain test result of sig2; (c) is a schematic diagram of a time domain test result of sig3; (d) is a schematic diagram of a time domain test result of sig4;

[0051] Figure 7 A time domain schematic diagram of a restored baseband signal provided by an embodiment of the present invention;

[0052] Figure 8 A schematic diagram of a demodulation test result of a recovered baseband signal provided in an embodiment of the present invention, wherein (a) represents a measurement time diagram, (b) represents a spectrum diagram, and (c) represents an output result schematic diagram. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0055] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0056] Additionally, descriptions of well-known structures, functions, and configurations may be omitted for clarity and conciseness.One of ordinary skill in the art will recognize that various changes and modifications may be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0057] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0058] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0059] Before introducing the specific implementation methods of this application, the concepts involved are first explained:

[0060] Example 1

[0061] like Figure 1 As shown, this embodiment provides an adaptive baseband signal recovery system, including:

[0062] The A / D sampling module is used to digitize the acquired down-converted RF signal to obtain a baseband signal with Doppler frequency shift;

[0063] The orthogonal decomposition module is used to perform real-time IQ decomposition of the baseband signal with Doppler frequency shift to obtain an in-phase signal I and an orthogonal signal Q;

[0064] A real-time IQ decomposition module includes four sub-signal calculation modules for performing four-way parallel calculations on the in-phase signal I and the orthogonal signal Q to obtain four sub-signals, which are respectively transmitted to the signal selector through corresponding signal transmission channels;

[0065] The parameter calculation module is used to determine the sub-signal transmitted at the current moment according to the Doppler phase at the current moment, and generate a control signal of the signal sorter and send it to the signal sorter, and at the same time calculate the amplitude correction coefficient according to the Doppler phase at the current moment and send it to the amplitude correction module;

[0066] A signal selector, used to switch to the signal transmission channel corresponding to the sub-signal currently being transmitted according to the control signal, and transmit the sub-signal currently being transmitted to the amplitude correction module;

[0067] The amplitude correction module is used to correct the currently transmitted sub-signal according to the amplitude correction coefficient to obtain a restored baseband signal.

[0068] In the digital modulation communication scenario, if the signal is compressed to find the pulse pressure peak, the amplitude error of the recovered signal will be particularly large. In order to avoid this situation, the signal is amplitude corrected in this application to expand the applicable scenarios.

[0069] Based on Figure 1 The specific processing process in each module of the system is as follows:

[0070] In the A / D sampling module, the digital processing includes:

[0071] After A / D sampling of the RF signal, a sampling signal is obtained; the sampling signal is quantized into a digital signal; and at the same time, the digital signal is down-converted in the digital domain using the signal generated by the DDS to obtain a baseband signal with Doppler frequency shift.

[0072] It should be noted that A / D sampling conversion and digital down-conversion processing are both commonly used methods and will not be described in detail in this application.

[0073] In the orthogonal decomposition module, the CORDIC algorithm is used to perform real-time IQ decomposition of the baseband signal with Doppler frequency shift to obtain the in-phase signal and the in-phase signal I and the orthogonal signal Q, where the I-path signal is I=sin(x+θ), the Q-path signal is Q=cos(x+θ), θ represents the phase modulation information, x represents the phase difference between the transmitted and received signals, x is in one of the four quadrants between 0-2π, and the frequency value of x is the Doppler frequency shift.

[0074] The four sub-signal calculation modules respectively perform the following calculation process to obtain four sub-signals:

[0075] Sig 1 =I+Q=sin(x+θ)+cos(x+θ)=sin(x+θ+0.25π)

[0076] Sig 2 =IQ=sin(x+θ)-cos(x+θ)=sin(x+θ-0.25π)

[0077] Sig 3 =-IQ=-sin(x+θ)-cos(x+θ)=sin(x+θ-0.75π)

[0078] Sig 4 =QI=cos(x+θ)-sin(x+θ)=sin(x+θ-1.25π);

[0079] Among them, the four sub-signals are located in four quadrants respectively, among which Sig 1 Corresponding to the first quadrant, Sig 2 Corresponding to the second quadrant, Sig 3Corresponding to the third quadrant, Sig 4 Corresponding to the fourth quadrant. And the above formula normalizes the amplitude in the simplified calculation.

[0080] The Doppler phase at the current moment is obtained in the parameter calculation module The calculation process is:

[0081]

[0082] in, Indicates the preset initial phase, ft indicates the current moment, and unwrap indicates The calculated phase is subjected to unwrapping calculation.

[0083] Specifically, in order to switch the signal sorter to the corresponding transmission channel, each sub-signal calculation module can be defined, and the calculation formulas of the four sub-signal calculation modules are fixed as follows:

[0084] Sig 1 =I+Q

[0085] Sig 2 =IQ

[0086] Sig 3 =-IQ

[0087] Sig 4 =QI

[0088] Therefore, the four sub-signal calculation modules are numbered respectively, and the parameter calculation module pre-stores the numbers of the signal transmission channels in the real-time IQ decomposition module and the quadrants corresponding to the sub-signals transmitted by the signal transmission channels. In this way, the corresponding transmission channel can be located according to the quadrant determined by the Doppler phase, and the process of determining the sub-signal transmitted at the current moment is as follows:

[0089] Determine the quadrant position of the Doppler phase at the current moment according to the Doppler phase at the current moment, and determine the number of the signal transmission channel according to the comparison between the quadrant position and the quadrant corresponding to each sub-signal channel;

[0090] A control signal is generated according to the number of the signal transmission channel to control the signal selector to switch to the corresponding signal transmission channel.

[0091] Amplitude correction factor A C The calculation process is:

[0092]

[0093] Among them, abs represents the absolute value function.

[0094] Example 2

[0095] Based on the system of Example 1, this embodiment provides an adaptive baseband signal recovery method and is described in conjunction with specific data. This embodiment takes the communication digital modulation signal transmission wavelength of 0.04 meters, the symbol rate of 1Msps, and the use of a raised cosine filter with a roll-off factor of 0.35 for shaping filtering as an example. Figure 2 It can be seen that when there is no Doppler frequency shift in the signal time domain, its demodulation is as follows Figure 3 As shown in (a)-(c), it can be seen that the demodulated EVM is about 0.8% rms. When the source speed is 3000m / s, the time domain waveform of the echo signal is as follows: Figure 4 As shown in the figure, in the case of Doppler frequency shift, the demodulation Figure 5 As shown in (a)-(c), it can be seen that the demodulation EVM is about 25% rms. Compared with the case without Doppler frequency shift, the demodulation quality is greatly affected. The system involved in the present invention can be used to recover the baseband signal and obtain the correct demodulation result. The specific implementation process is as follows:

[0096] S1, obtaining a down-converted radio frequency signal, and digitizing the radio frequency signal to obtain a baseband signal with a Doppler frequency shift;

[0097] The A / D sampling module performs A / D sampling on the down-converted RF signal and quantizes it into a digital signal. At the same time, the signal generated by DDS is used to down-convert the aforementioned signal in the digital domain to obtain a baseband signal with Doppler frequency shift.

[0098] S2, performing real-time IQ decomposition on the baseband signal with Doppler frequency shift to obtain an in-phase signal and an orthogonal signal;

[0099] In the digital domain, the CORDIC algorithm is used to perform real-time IQ decomposition on the baseband signal with Doppler frequency shift obtained in step 1 to obtain a pair of orthogonal signals I and Q, such as Figure 4 shown.

[0100] S3, perform four-way parallel calculation on the in-phase signal and the orthogonal signal to obtain four sub-signals and transmit them to the signal selector through their corresponding signal transmission channels respectively;

[0101] The in-phase signal and the orthogonal signal are calculated in four parallel paths to obtain four sub-signals as follows: Figure 6 (a) Sig 1 =I+Q, such as Figure 6 (b) Sig 2 =IQ, such as Figure 6 (c) Sig 3 = -IQ, such as Figure 6(d) Sig 4 =QI;

[0102] S4, obtaining the Doppler phase at the current moment, determining the sub-signal transmitted at the current moment according to the Doppler phase, and controlling the signal sorter to switch to the corresponding signal transmission channel according to the sub-signal transmitted at the current moment, and calculating the amplitude correction coefficient according to the Doppler phase;

[0103] In the parameter calculation module, the quadrant corresponding to the current moment, that is, the phase of the Doppler frequency shift signal, is calculated. The first quadrant corresponds to 0~0.5π, the second quadrant corresponds to 0.5π~π, the third quadrant corresponds to -0.5π~0, and the fourth quadrant corresponds to -π~0.5π; then the calculated quadrant is used to generate the corresponding control signal, that is, the sub-signal Sig is selected in the first quadrant. 1 , select sub-signal Sig in the second quadrant 2 , select sub-signal Sig in the three quadrants 3 , select sub-signal Sig in the four quadrants 4 , the sub-signal is always in phase with the baseband signal;

[0104] For example, at time 5555.75us, the phase of the Doppler frequency shift is 2.2777rad, then it is judged to be in the second-phase quadrant, and the parameter calculation module outputs the selected sub-signal Sig 2 control signal;

[0105] The amplitude correction factor at the current moment can be calculated as

[0106]

[0107] S5. Obtain the sub-signal currently transmitted through the signal selector, and correct the sub-signal using the amplitude correction coefficient to obtain a restored baseband signal.

[0108] The signal selector is a four-to-one signal selector. The four-to-one signal selector selects the corresponding branched sub-signal for output according to the control signal sent by the parameter calculation module to obtain the restored baseband signal. For example, at time 5555.75us, the parameter calculation module outputs the selected sub-signal Sig 2 The control signal of the four-to-one signal selector selects the sub-signal Sig 2 .

[0109] In the amplitude correction module, the signal is amplitude corrected, that is, multiplied by the amplitude correction coefficient A C And output to get the restored baseband signal.

[0110] For example, at time 5555.75us, the amplitude correction module will perform amplitude correction before the signal is output, and the correction coefficient is 0.753, which is calculated and given in the parameter calculation module.

[0111] like Figure 7-Figure 8 This is an experimental result diagram obtained according to the above example. It can be seen that this embodiment can successfully recover the digital modulation baseband signal from the signal with Doppler frequency shift. The waveform of the recovered baseband digital modulation signal is as follows: Figure 7 As shown, the demodulation result of the restored baseband digital modulation signal is as follows Figure 8 As shown in (a)-(c), the demodulation EVM is about 1.7% rms, which is significantly reduced compared with the demodulation result of the baseband signal with Doppler frequency shift. This result shows that the method proposed in this application can be used as a baseband signal recovery method to adaptively eliminate Doppler frequency shift.

[0112] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. An adaptive baseband signal recovery system, characterized in that: include: The A / D sampling module is used to digitize the acquired down-converted RF signal to obtain a baseband signal with Doppler frequency shift; The orthogonal decomposition module is used to perform real-time IQ decomposition of the baseband signal with Doppler frequency shift to obtain an in-phase signal I and an orthogonal signal Q; A real-time IQ decomposition module includes four sub-signal calculation modules for performing four-way parallel calculations on the in-phase signal I and the orthogonal signal Q to obtain four sub-signals, which are respectively transmitted to the signal selector through corresponding signal transmission channels; The parameter calculation module is used to determine the sub-signal transmitted at the current moment according to the Doppler phase at the current moment, and generate a control signal of the signal sorter and send it to the signal sorter, and at the same time calculate the amplitude correction coefficient according to the Doppler phase at the current moment and send it to the amplitude correction module; A signal selector, used to switch to the signal transmission channel corresponding to the sub-signal currently being transmitted according to the control signal, and transmit the sub-signal currently being transmitted to the amplitude correction module; The amplitude correction module is used to correct the currently transmitted sub-signal according to the amplitude correction coefficient to obtain a restored baseband signal.

2. The adaptive baseband signal recovery system according to claim 1, characterized in that: Digital processing includes: After A / D sampling of the RF signal, a sampling signal is obtained; the sampling signal is quantized into a digital signal; and at the same time, the digital signal is down-converted in the digital domain using the signal generated by the DDS to obtain a baseband signal with Doppler frequency shift.

3. The adaptive baseband signal recovery system according to claim 1, characterized in that: In the orthogonal decomposition module, the CORDIC algorithm is used to perform real-time IQ decomposition of the baseband signal with Doppler frequency shift to obtain the in-phase signal I and the orthogonal signal Q, where the in-phase signal I is: I = sin(x + θ), and the orthogonal signal Q is: Q = cos(x + θ), θ represents the phase modulation information, x represents the phase difference between the transmitted and received signals, and the frequency value of x is the Doppler frequency shift.

4. The adaptive baseband signal recovery system according to claim 3, characterized in that: The four sub-signal calculation modules respectively perform the following calculation process to obtain four sub-signals: Sig1=I+Q=sin(x+θ)+cos(x+θ)=sin(x+θ+0.25π) Sig2=IQ=sin(x+θ)-cos(x+θ)=sin(x+θ-0.25π) Sig3=-IQ=-sin(x+θ)-cos(x+θ)=sin(x+θ-0.75π) Sig4=QI=cos(x+θ)-sin(x+θ)=sin(x+θ-1.25π).

5. The adaptive baseband signal recovery system according to claim 1, characterized in that: The Doppler phase at the current moment is obtained in the parameter calculation module The calculation process is: in, Indicates the preset initial phase, ft indicates the current moment, and unwrap indicates The calculated phase is subjected to unwrapping calculation.

6. The adaptive baseband signal recovery system according to claim 5, characterized in that: The parameter calculation module pre-stores the numbers of each signal transmission channel in the real-time IQ decomposition module and the quadrants corresponding to the sub-signals transmitted by each signal transmission channel. The process of determining the sub-signal transmitted at the current moment is: Determine the quadrant position of the Doppler phase at the current moment according to the Doppler phase at the current moment, and determine the number of the signal transmission channel according to the comparison between the quadrant position and the quadrant corresponding to each sub-signal channel; A control signal is generated according to the number of the signal transmission channel to control the signal selector to switch to the corresponding signal transmission channel.

7. The adaptive baseband signal recovery system according to claim 5, characterized in that: Amplitude correction factor A C The calculation process is: Among them, abs represents the absolute value function.

8. An adaptive baseband signal recovery method, characterized in that: The specific steps include: S1, obtaining a down-converted radio frequency signal, and digitizing the radio frequency signal to obtain a baseband signal with a Doppler frequency shift; S2, performing real-time IQ decomposition on the baseband signal with Doppler frequency shift to obtain an in-phase signal and an orthogonal signal; S3, performing four-way parallel calculation on the in-phase signal and the orthogonal signal to obtain four sub-signals and transmitting them to the signal selector through their corresponding signal transmission channels respectively; S4, obtaining the Doppler phase at the current moment, determining the sub-signal transmitted at the current moment according to the Doppler phase, and controlling the signal sorter to switch to the corresponding signal transmission channel according to the sub-signal transmitted at the current moment, and calculating the amplitude correction coefficient according to the Doppler phase; S5. Obtain the sub-signal currently transmitted through the signal selector, and correct the sub-signal using the amplitude correction coefficient to obtain a restored baseband signal.

9. The adaptive baseband signal recovery method according to claim 8, characterized in that: The Doppler phase at the current moment is obtained in the parameter calculation module The calculation process is: in, Indicates the preset initial phase, ft indicates the current moment, and unwrap indicates The calculated phase is subjected to unwrapping calculation.

10. The adaptive baseband signal recovery method according to claim 9, characterized in that: Amplitude correction factor A C The calculation process is: Among them, abs represents the absolute value function.

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