Satellite-borne multi-carrier wideband dispersion transmitting link system and digital pre-distortion compensation method

Abstract

The application relates to a satellite-borne multi-carrier wideband dispersion transmission link system and a digital pre-distortion compensation method. The system comprises a joint pre-distortion executor unit, a JESD204 interface module, an RFSoC module, a multi-carrier transmission channel, a first multiplexer, a second multiplexer, a high-speed data acquisition module, a soft-core computing unit, a refreshing and reconstructing unit, a parameter reading and writing module, and a power amplifier working point control and switch selection module. The joint pre-distortion executor unit is used to eliminate the group delay distortion and unbalance influence in the satellite-borne transmission link. Meanwhile, on the basis of compensating linear distortion, the GMP model is realized based on a lookup table structure at the transmission end, is used to compensate the strong nonlinearity and memory characteristics of a power amplifier, and is favorable for improving the modeling precision of the satellite power amplifier. The application is favorable for improving constellation vector amplitude error, is also favorable for reducing the design reserved bandwidth between adjacent carriers of a final-stage duplexer, and is favorable for improving frequency band utilization.

Description

Technical Field

[0001] This application relates to the field of high-speed satellite data transmission, specifically to a spaceborne multi-carrier broadband dispersive transmission link system and a digital predistortion compensation method. Background Technology

[0002] To meet the growing demand for real-time and reliable data transmission from remote sensing satellite payloads to the ground, the transmission frequency bands of satellite-to-ground links have evolved from X to higher frequency bands such as Ka, Q / V, and W, and the modulation methods have shifted towards higher-order modulation schemes. Increasing signal bandwidth and adopting higher-order modulation schemes in the high-frequency band can improve the transmission rate of satellite-to-ground links; however, the nonlinearity of power amplifiers and the dispersion effect of RF channel filters can exacerbate and degrade the communication error performance of broadband high-order modulated signals.

[0003] Traditional digital pre-distortion (DPD) is mainly used for the linearization of power amplifiers. However, in actual satellite launch links, quadrature modulation chips inevitably have amplitude / phase imbalances, and radio frequency channel filters have group delay distortions, making it difficult to ensure that the traditional DPD model and the nonlinear model of the satellite power amplifier achieve accurate matching. Summary of the Invention

[0004] To overcome at least one deficiency in the prior art, this application provides a spaceborne multi-carrier broadband dispersive transmission link system and a digital predistortion compensation method.

[0005] In the first aspect, a spaceborne multi-carrier broadband dispersive transmission link system is provided, including: a joint predistortion actuator unit, a JESD204 interface module, an RFSoC module, a multi-carrier transmission channel, a first multiplexer, a second multiplexer, a high-speed data acquisition module, a soft-core computing unit, a refresh and reconstruction unit, a parameter reading and writing module, and a power amplifier operating point control and switching selection module.

[0006] The joint predistortion actuator unit receives multi-channel raw digital baseband signals, performs orthogonal modulation error correction based on the measured orthogonal phase error, obtains multi-channel phase-corrected raw digital baseband signals, and performs joint predistortion compensation based on the bound nonlinear predistortion parameters and linear predistortion parameters to obtain compensated multi-channel digital baseband signals. The JESD204 interface module is used to receive the compensated multi-channel digital baseband signal, perform data conversion processing, and obtain the converted multi-channel digital baseband signal. The RFSoC module performs analog-to-digital conversion on the converted multi-channel digital baseband signal to obtain a multi-channel analog baseband signal; The multi-carrier transmission channel modulates the multi-channel analog baseband signal to obtain a multi-channel radio frequency modulated signal; the multi-channel radio frequency modulated signal is filtered and amplified to obtain a multi-channel power modulated signal; based on the carrier frequency of the power modulated signal, the power modulated signal of each channel is determined to be either a power modulated satellite signal or a power modulated ground signal. The first multiplexer combines all power-modulated ground signals to obtain a single ground multicarrier power-modulated signal. The second multiplexer combines all the power modulated satellite signals to obtain a single satellite multi-carrier power modulated signal. The high-speed data acquisition module performs down-conversion, analog-to-digital conversion and digital resampling on the ground multi-carrier power modulation signal to obtain a multi-channel feedback digital baseband signal. The soft-core computing unit obtains the nonlinear predistortion parameters and the linear predistortion parameters based on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal; The parameter read / write module is used to receive nonlinear predistortion parameters and linear predistortion parameters, and store them in the refresh and reconstruction unit. When needed, the linear predistortion parameters and nonlinear predistortion parameters are bound to the joint predistortion actuator unit from the refresh and reconstruction unit according to the address index. The power amplifier operating point control and switch selection module is used to acquire the solenoid current telemetry of the power amplifier in the multi-carrier transmit channel to obtain the operating point of the power amplifier and the input power backoff setting; and to control the switch matrix of the multi-carrier transmit channel to select the signal output.

[0007] In one embodiment, the combined predistortion actuator unit includes multiple combined predistortion actuators, each of which receives a channel of raw digital baseband signal; Each joint predistortion actuator includes a quadrature modulation error corrector (QEC), a digital phase shifter (DPD) actuator module, and a linear pre-equalizer. The QEC receives the original digital baseband signal and corrects the phase imbalance introduced by the quadrature inverter in the multi-carrier transmit channel based on the measured quadrature phase error, obtaining the phase-corrected original digital baseband signal. The DPD actuator module receives the phase-corrected original digital baseband signal and compensates for the strong nonlinearity and memory characteristics introduced by the power amplifier in the multi-carrier transmit channel based on the bound nonlinear predistortion parameters. The linear pre-equalizer compensates for the dispersion characteristics caused by the delay of the first multiplexer group based on the bound linear predistortion parameters.

[0008] In one embodiment, the DPD actuator module includes: a CORDIC module; a first delay unit, a second delay unit, a third delay unit, a fourth delay unit, a fifth delay unit, a sixth delay unit, a seventh delay unit, an eighth delay unit, a ninth delay unit, and a tenth delay unit; a first RAM, a second RAM, a third RAM, a fourth RAM, a fifth RAM, a sixth RAM, a seventh RAM, an eighth RAM, a ninth RAM, a tenth RAM, an eleventh RAM, and a twelfth RAM; a first complex multiply-accumulate unit, a second complex multiply-accumulate unit, a third complex multiply-accumulate unit, and a fourth complex multiply-accumulate unit; and a first accumulator. The read address signal ports of the first RAM, the second RAM, and the third RAM are all connected to the CORDIC module, the read data signal ports are all connected to the first complex multiply-accumulate, and the write address signal port and the write data signal port are connected to the parameter read / write module. The read address signal ports of the fourth RAM, fifth RAM, and sixth RAM are all connected to the second delay unit, the read data signal port is connected to the second complex multiply-accumulate unit, and the write address signal port and write data signal port are connected to the parameter read / write module. The read address signal ports of the seventh RAM, the eighth RAM, and the ninth RAM are connected to the fourth delay unit, the read data signal ports are connected to the third complex multiply-accumulate unit, and the write address signal ports and write data signal ports are connected to the parameter read / write module. The read address signal ports of the 10th RAM, 11th RAM, and 12th RAM are connected to the 6th delay unit, the read data signal ports are connected to the 4th complex multiply-accumulate unit, and the write address signal ports and write data signal ports are connected to the parameter read / write module. The first accumulator is connected to the output ports of the first complex multiplication accumulator, the second complex multiplication accumulator, the third complex multiplication accumulator, and the fourth complex multiplication accumulator. The first delay unit, the third delay unit, the fifth delay unit, the tenth delay unit, and the fourth complex multiplication accumulator are connected in sequence; The phase-corrected original digital baseband signal is input to the first delay unit, the CORDIC module, and the seventh delay unit, respectively.

[0009] In one embodiment, the linear pre-equalizer includes: eight delay units, nine complex multipliers, and a second accumulator; Eight delay units are connected in sequence, and the outputs of the eight delay units are each connected to a complex multiplier; the outputs of the nine complex multipliers are connected to a second accumulator. All nine complex multipliers are connected to a parameter read / write module for binding linear predistortion parameters.

[0010] In one embodiment, the RFSoC module includes multiple baseband digital-to-analog converters (DACs), each including an I-branch DAC and a Q-branch DAC, for performing analog-to-digital conversion on the I-component signal and the Q-component signal of the digital baseband signal, respectively.

[0011] In one embodiment, the multi-carrier transmit channel includes multiple transmit channel units and a switching matrix. Each transmit channel unit includes an orthogonal frequency converter, an analog bandpass filter, a power amplifier, and an isolator. Each transmit channel unit receives an analog baseband signal from one channel. The quadrature inverter orthogonally modulates the analog baseband signal into a radio frequency modulated signal with a specific carrier frequency. The analog bandpass filter performs channel filtering on the radio frequency modulated signal, the power amplifier amplifies the power of the channel-filtered signal, and then the signal is isolated by an isolator to output the power modulated signal. If there is only one carrier frequency in the output multi-channel power modulation signal, then the power modulation signal corresponding to that carrier frequency is a power modulation signal to satellite. If there is more than one carrier frequency in the output multi-channel power modulation signal, then the power modulation signal corresponding to that carrier frequency is a power modulation signal to ground. The switching matrix outputs all power-modulated satellite signals to the second multiplexer and all power-modulated ground signals to the first multiplexer.

[0012] In one embodiment, the high-speed data acquisition module includes a frequency conversion module, an analog-to-digital converter, and a vector signal processing module, which are used to perform down-conversion, analog-to-digital conversion, and digital resampling processing on the ground multi-carrier power modulation signal, respectively.

[0013] In one embodiment, the soft-core computing unit includes a linear blind equalizer, a preprocessing module, and a joint DPD coefficient extraction module; The linear blind equalizer accepts multi-channel feedback digital baseband signals, uses the LMS algorithm to obtain equalizer tap coefficients, and outputs the equalizer tap coefficients as linear predistortion parameters to the parameter read / write module after fixed-point quantization. The preprocessing module performs frequency deviation, phase deviation elimination, and time domain alignment processing on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal, and outputs the aligned feedback digital baseband signal and the original digital baseband signal after phase correction. The joint DPD coefficient extraction module uses the least squares method to solve for the estimated coefficient vector of DPD by matrix inversion based on the aligned feedback digital baseband signal and the phase-corrected original digital baseband signal. The estimated value is then output as a nonlinear predistortion parameter to the parameter reading and writing module after fixed-point quantization.

[0014] In one embodiment, the refresh and reconfiguration unit includes a timed refresh chip and a Flash memory.

[0015] Secondly, a digital predistortion compensation method is provided, based on the aforementioned spaceborne multi-carrier broadband dispersive transmission link system, including: Step 1: Set the initial state modulation mode to where n is the modulation order; Step 2: Actual measurement of the phase imbalance error of the quadrature inverter in the multi-carrier transmission channel. The original I-branch digital baseband signal is processed. Multiply-accumulate processing is performed on the original Q-branch digital baseband signal. Multiply-accumulate processing yields the phase-corrected original digital baseband signal.

[0016] Step 3: Load the initial state parameters of the linear pre-equalizer; Step 4: Collect remote measurements of the solenoid current of the power amplifier in the multi-carrier transmission channel and set the power amplifier to its actual working state; Step 5: Acquire the ground-based multi-carrier power modulation signal, perform down-conversion, analog-to-digital conversion and digital resampling processing to obtain a multi-channel feedback digital baseband signal; Step 6: Perform linear blind equalization iteration at the receiving end and use the LMS algorithm to obtain the equalizer tap coefficients; Step 7: When the error signal approaches zero, the equalizer tap coefficients are quantized at fixed point and output as linear predistortion parameters to the parameter read / write module; the parameter read / write module stores them in the refresh and reconstruction unit, completing the extraction of linear predistortion parameters and the storage without power loss. Step 8: The parameter read / write module reads the linear predistortion parameters from the refresh and reconstruction unit, binds them to the linear preequalizer, and completes the process. Modulation mode compensation for linear distortion of satellite channels; Step 9: Perform frequency deviation, phase deviation elimination and time domain alignment processing on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal, and output the aligned feedback digital baseband signal and the original digital baseband signal after phase correction. Step 10: Based on the aligned feedback digital baseband signal and the phase-corrected original digital baseband signal, the coefficient vector estimate of DPD is solved by matrix inversion using the least squares method, and then output as nonlinear predistortion parameter to the parameter read / write module after fixed-point quantization; and stored in the refresh and reconstruction unit through the parameter read / write module to complete the extraction of nonlinear predistortion parameters and power-off non-loss storage.

[0017] Compared with the prior art, this application has the following beneficial effects: 1. The spaceborne multi-carrier broadband dispersive transmission link system and digital predistortion compensation method of this application employ a joint predistortion actuator unit at the transmitter end to eliminate group delay distortion and imbalance effects in the spaceborne transmission link, effectively improving constellation diagram vector amplitude errors. Simultaneously, based on linear distortion compensation, a GMP model is implemented at the transmitter end using a lookup table structure to compensate for the strong nonlinearity and memory characteristics of the power amplifier, which is beneficial for improving the modeling accuracy of the satellite power amplifier. This application helps to reduce the design reserve protection bandwidth between adjacent carriers of the final-stage multiplexer, thus improving bandwidth utilization.

[0018] 2. This application improves the quality-efficiency ratio, integration, and reliability of the spaceborne multi-carrier transmission system. The RFSoC used in this application integrates multiple digital-to-analog converters and analog-to-digital converters, which can be used not only for digital-to-analog conversion in the transmission channel but also for analog-to-digital conversion in the feedback reception channel. The system also has multi-carrier ground-to-satellite transmission capabilities, with redundant output of ground signals for each carrier frequency, resulting in high reliability. Attached Figure Description

[0019] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings, which, together with the detailed description below, are incorporated in and form part of this specification. In the drawings: Figure 1 A schematic diagram of a spaceborne multi-carrier broadband dispersive transmission link system is shown. Figure 2 The amplitude-frequency response curve and group delay response curve of the first multiplexer are shown; Figure 3 A schematic diagram of the DPD actuator module is shown; Figure 4 A schematic diagram of a linear pre-equalizer is shown.

[0020] Figure label: 1—First delay unit, 2—Second delay unit, 3—Third delay unit, 4—Fourth delay unit, 5—Fifth delay unit, 6—Sixth delay unit, 7—Seventh delay unit, 8—Eighth delay unit, 9—Ninth delay unit, 10—Tenth delay unit, 11—CORDIC module, 12—First RAM, 13—Second RAM, 14—Third RAM, 15—Fourth RAM, 16—Fifth RAM, 17—Sixth RAM, 18—Seventh RAM, 19—Eighth RAM, 20—Ninth RAM, 21—Tenth RAM, 22—Eleventh RAM, 23—Twelfth RAM, 24—First complex multiply-accumulator, 25—Second complex multiply-accumulator, 26—Third complex multiply-accumulator, 27—Fourth complex multiply-accumulator, 28—First accumulator. Detailed Implementation

[0021] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer’s specific objectives, and these decisions may vary as the embodiments differ.

[0022] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution according to this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0023] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.

[0024] This application provides a spaceborne multi-carrier broadband dispersive transmission link system. Figure 1 A schematic diagram of a spaceborne multi-carrier broadband dispersive transmission link system is shown. (See attached diagram) Figure 1 The system includes: a combined predistortion actuator unit, a JESD204 interface module, an RFSoC module, a multi-carrier transmit channel, a first multiplexer, a second multiplexer, a high-speed data acquisition module, a soft-core computing unit, a refresh and reconstruction unit, a parameter read / write module, and a power amplifier operating point control and switch selection module. The functions of each module are described in detail below.

[0025] The joint predistortion actuator unit receives multi-channel raw digital baseband signals, performs quadrature modulation error correction (QEC) based on the measured quadrature phase error, obtains multi-channel phase-corrected raw digital baseband signals, and performs joint predistortion compensation based on the bound nonlinear predistortion parameters and linear predistortion parameters to obtain compensated multi-channel digital baseband signals. The JESD204 interface module is used to receive the compensated multi-channel digital baseband signal, perform data conversion processing, and obtain the converted multi-channel digital baseband signal. The RFSoC module performs analog-to-digital conversion on the converted multi-channel digital baseband signal to obtain a multi-channel analog baseband signal; The multi-carrier transmission channel modulates the multi-channel analog baseband signal to obtain a multi-channel radio frequency modulated signal; the multi-channel radio frequency modulated signal is filtered and amplified to obtain a multi-channel power modulated signal; based on the carrier frequency of the power modulated signal, the power modulated signal of each channel is determined to be either a power modulated satellite signal or a power modulated ground signal. The first multiplexer combines all power-modulated ground signals to obtain a ground-based multi-carrier power-modulated signal. Here, each filter passband of the first multiplexer has an inherent parabolic group delay characteristic, and the dispersion characteristic of the group delay will cause severe diffusion of the constellation point distribution of the broadband high-order modulation signal, thereby reducing the communication error rate performance. Figure 2 The amplitude-frequency response curve and group delay response curve of the first multiplexer are shown.

[0026] The second multiplexer combines all the power modulated satellite signals to obtain a single satellite multi-carrier power modulated signal. The high-speed data acquisition module performs down-conversion, analog-to-digital conversion and digital resampling on the ground multi-carrier power modulation signal to obtain a multi-channel feedback digital baseband signal. The soft-core computing unit obtains the nonlinear predistortion parameters and the linear predistortion parameters based on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal; The parameter read / write module is used to receive nonlinear predistortion parameters and linear predistortion parameters, and store them in the refresh and reconstruction unit. When needed, the linear predistortion parameters and nonlinear predistortion parameters are bound to the joint predistortion actuator unit from the refresh and reconstruction unit according to the address index. The power amplifier operating point control and switch selection module is used to acquire the solenoid current telemetry of the power amplifier in the multi-carrier transmit channel to obtain the operating point of the power amplifier and the input power backoff setting; and to control the switch matrix of the multi-carrier transmit channel to select the signal output.

[0027] In one embodiment, the combined predistortion actuator unit includes multiple combined predistortion actuators, each of which receives a channel of raw digital baseband signal; Each joint predistortion actuator includes Each joint predistortion actuator includes a quadrature modulation error corrector (QEC), a DPD actuator module, and a linear pre-equalizer; the QEC receives the original digital baseband signal and performs quadrature modulation error correction on the phase imbalance introduced by the quadrature inverter in the multi-carrier transmit channel based on the measured quadrature phase error, to obtain the phase-corrected original digital baseband signal; the DPD actuator module receives the phase-corrected original digital baseband signal and compensates for the strong nonlinearity and memory characteristics introduced by the power amplifier in the multi-carrier transmit channel based on the bound nonlinear predistortion parameters; the linear pre-equalizer compensates for the dispersion characteristics caused by the delay of the first multiplexer group based on the bound linear predistortion parameters.

[0028] Here, the first DPD actuator module adopts... The lookup table structure of the GMP model is implemented, where, Depth of memory for primary items The order of the main term nonlinearity For the memory depth of delayed cross terms, The nonlinear order of the delayed cross term The cross order of the delayed cross term. For the memory depth of feedforward cross terms, The nonlinear order of the feedforward cross term, is the cross order of the feedforward cross term.

[0029] The linear pre-equalizer is implemented using a parallel 9th-order complex filter structure.

[0030] In one embodiment, Figure 3 A schematic diagram of the DPD actuator module is shown; see [link / reference]. Figure 3 The DPD actuator module includes: a CORDIC module 11; a first delay unit 1, a second delay unit 2, a third delay unit 3, a fourth delay unit 4, a fifth delay unit 5, a sixth delay unit 6, a seventh delay unit 7, an eighth delay unit 8, a ninth delay unit 9, and a tenth delay unit 10; a first RAM 12, a second RAM 13, a third RAM 14, a fourth RAM 15, a fifth RAM 16, a sixth RAM 17, a seventh RAM 18, an eighth RAM 19, a ninth RAM 20, a tenth RAM 21, an eleventh RAM 22, and a twelfth RAM 23; a first complex multiply-accumulate unit 24, a second complex multiply-accumulate unit 25, a third complex multiply-accumulate unit 26, a fourth complex multiply-accumulate unit 27; and a first accumulator 28. The read address signal ports of the first RAM 12, the second RAM 13, and the third RAM 14 are all connected to the CORDIC module 11, the read data signal ports are all connected to the first complex multiply accumulator 24, and the write address signal port and the write data signal port are connected to the parameter read and write module. The read address signal ports of the fourth RAM 15, the fifth RAM 16, and the sixth RAM 17 are all connected to the second delay unit 2, the read data signal ports are connected to the second complex multiply accumulator 25, and the write address signal ports and write data signal ports are connected to the parameter read / write module 9. The read address signal ports of the seventh RAM18, the eighth RAM19, and the ninth RAM20 are connected to the fourth delay unit 4, the read data signal ports are connected to the third complex multiply accumulator 26, and the write address signal ports and write data signal ports are connected to the parameter read and write module. The read address signal ports of the tenth RAM 21, the eleventh RAM 22, and the twelfth RAM 23 are connected to the sixth delay unit 6, the read data signal ports are connected to the fourth complex multiply accumulator 27, and the write address signal ports and write data signal ports are connected to the parameter read and write module. The first accumulator 28 is connected to the output ports of the first complex multiplication accumulator 24, the second complex multiplication accumulator 25, the third complex multiplication accumulator 26, and the fourth complex multiplication accumulator 27. The first delay unit 1, the third delay unit 3, the fifth delay unit 5, the tenth delay unit 10 and the fourth complex multiplication accumulator 27 are connected in sequence; The phase-corrected original digital baseband signal is input to the first delay unit 1, the CORDIC module 11, and the seventh delay unit 7, respectively.

[0031] In one embodiment, Figure 4 A schematic diagram of a linear pre-equalizer is shown; see [link / reference]. Figure 4 The linear pre-equalizer includes: eight delay units, nine complex multipliers, and a second accumulator; Eight delay units are connected in sequence, and the outputs of the eight delay units are each connected to a complex multiplier. The remaining complex multiplier and the first delay unit among the eight delay units receive the signal output by the DPD actuator module; the outputs of the nine complex multipliers are connected to the second accumulator. All nine complex multipliers are connected to a parameter read / write module for binding linear predistortion parameters.

[0032] In one embodiment, the RFSoC module includes multiple baseband digital-to-analog converters (DACs), each including an I-branch DAC and a Q-branch DAC, used for analog-to-digital conversion of the I-component and Q-component signals of the digital baseband signal, respectively. Depending on the actual application scenario, the RFSoC module can be implemented using the JFM9RFVU3P5G RFSoC, which can be used to implement 8 sets of baseband DACs.

[0033] In one embodiment, the multi-carrier transmit channel includes multiple transmit channel units and a switching matrix. Each transmit channel unit includes an orthogonal frequency converter, an analog bandpass filter, a power amplifier, and an isolator. Each transmit channel unit receives an analog baseband signal from one channel. The quadrature inverter orthogonally modulates the analog baseband signal into a radio frequency modulated signal with a specific carrier frequency. The analog bandpass filter performs channel filtering on the radio frequency modulated signal, the power amplifier amplifies the power of the channel-filtered signal, and then the signal is isolated by an isolator to output the power modulated signal. If there is only one carrier frequency in the output multi-channel power modulation signal, then the power modulation signal corresponding to that carrier frequency is a power modulation signal to satellite. If there is more than one carrier frequency in the output multi-channel power modulation signal, then the power modulation signal corresponding to that carrier frequency is a power modulation signal to ground. The switching matrix outputs all power-modulated satellite signals to the second multiplexer and all power-modulated ground signals to the first multiplexer.

[0034] Here, the carrier frequency of the RF modulation signal in the first channel is... or The carrier frequency of the radio frequency modulation signal in the second channel is or And so on, the carrier frequency of the RF modulation signal of the Nth channel is or In actual operation, if only the carrier frequency of the RF modulation signal of the first channel is... The carrier frequency of the power modulation signal for all channels is If there is only one signal, then the power modulation signal corresponding to the first channel is the power modulation signal to satellite. The power modulation signals corresponding to the other channels are the power modulation signals to ground.

[0035] In one embodiment, the high-speed data acquisition module includes a frequency conversion module, an analog-to-digital converter, and a vector signal processing module, which are used to perform down-conversion, analog-to-digital conversion, and digital resampling processing on the ground multi-carrier power modulation signal, respectively.

[0036] In one embodiment, the soft-core computing unit includes a linear blind equalizer, a preprocessing module, and a joint DPD coefficient extraction module; The linear blind equalizer accepts multi-channel feedback digital baseband signals, uses the LMS algorithm to obtain the equalizer tap coefficients, and then performs fixed-point quantization on these coefficients, outputting them as linear predistortion parameters to the parameter read / write module. The equalizer tap coefficients are 9th-order complex equalizer tap coefficients, with a micro-iteration step size of [missing value]. Magnitude.

[0037] The preprocessing module performs frequency deviation, phase deviation elimination, and time domain alignment processing on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal, and outputs the aligned feedback digital baseband signal and the original digital baseband signal after phase correction. The joint DPD coefficient extraction module uses the least squares method to solve for the estimated coefficient vector of DPD by matrix inversion based on the aligned feedback digital baseband signal and the phase-corrected original digital baseband signal. The estimated value is then output as a nonlinear predistortion parameter to the parameter reading and writing module after fixed-point quantization.

[0038] In one embodiment, the refresh and reconfiguration unit includes a timed refresh chip and a Flash memory. The refresh and reconfiguration unit serves two purposes: firstly, it improves the radiation resistance of digital devices through timed refresh; secondly, it enables power-adjusted, non-linear predistortion parameters for storage and read / write without data loss. Depending on the application scenario, the timed refresh chip can be implemented using JFMRS01RH, A3PE300, or JRTAX2000.

[0039] This application also provides a digital predistortion compensation method based on the aforementioned spaceborne multi-carrier broadband dispersive transmission link system. The method includes: Step 1: Set the initial state modulation mode to n is the modulation order, which can be 4; Step 2: Actual measurement of the phase imbalance error of the quadrature inverter in the multi-carrier transmission channel. The original I-branch digital baseband signal is processed. Multiply-accumulate processing is performed on the original Q-branch digital baseband signal. Multiply-accumulate processing yields the phase-corrected original digital baseband signal. Among these... Represents the sine function. This represents the cosine function. The original I-branch digital baseband signal and the original Q-branch digital baseband signal are the two branch signals of the original digital baseband signal.

[0040] Step 3: Linear pre-equalizer sets initial state parameters. ; Step 4: Collect remote measurements of the solenoid current of the power amplifier in the multi-carrier transmission channel and set the power amplifier to its actual working state; Step 5: Acquire the ground-based multi-carrier power modulation signal, perform down-conversion, analog-to-digital conversion and digital resampling processing to obtain a multi-channel feedback digital baseband signal; Step 6: Perform linear blind equalization iteration at the receiving end and use the LMS algorithm to obtain the equalizer tap coefficients; Step 7: When the error signal approaches zero, the equalizer tap coefficients are quantized at fixed point and output as linear predistortion parameters to the parameter read / write module; the parameter read / write module stores them in the refresh and reconstruction unit, completing the extraction of linear predistortion parameters and the storage without power loss. Step 8: The parameter read / write module reads the linear predistortion parameters from the refresh and reconstruction unit, binds them to the linear preequalizer, and completes the process. Modulation mode compensation for linear distortion of satellite channels; Step 9: Perform frequency deviation, phase deviation elimination and time domain alignment processing on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal, and output the aligned feedback digital baseband signal and the original digital baseband signal after phase correction. Step 10: Based on the aligned feedback digital baseband signal and the phase-corrected original digital baseband signal, the coefficient vector estimate of DPD is solved by matrix inversion using the least squares method, and then output as nonlinear predistortion parameter to the parameter read / write module after fixed-point quantization; and stored in the refresh and reconstruction unit through the parameter read / write module to complete the extraction of nonlinear predistortion parameters and power-off non-loss storage.

[0041] In summary, this application has the following technical effects: 1. The spaceborne multi-carrier broadband dispersive transmission link system and digital predistortion compensation method of this application employ a joint predistortion actuator unit at the transmitter end to eliminate group delay distortion and imbalance effects in the spaceborne transmission link, effectively improving constellation diagram vector amplitude errors. Simultaneously, based on linear distortion compensation, a GMP model is implemented at the transmitter end using a lookup table structure to compensate for the strong nonlinearity and memory characteristics of the power amplifier, which is beneficial for improving the modeling accuracy of the satellite power amplifier. This application helps to reduce the design reserve protection bandwidth between adjacent carriers of the final-stage multiplexer, thus improving bandwidth utilization.

[0042] 2. This application improves the quality-efficiency ratio, integration, and reliability of the spaceborne multi-carrier transmission system. The RFSoC used in this application integrates multiple digital-to-analog converters and analog-to-digital converters, which can be used not only for digital-to-analog conversion in the transmission channel but also for analog-to-digital conversion in the feedback reception channel. The system also has multi-carrier ground-to-satellite transmission capabilities, with redundant output of ground signals for each carrier frequency, resulting in high reliability.

[0043] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A spaceborne multi-carrier broadband dispersive transmission link system, characterized in that, include: Combined predistortion actuator unit, JESD204 interface module, RFSoC module, multi-carrier transmit channel, first multiplexer, second multiplexer, high-speed data acquisition module, soft core computing unit, refresh and reconfiguration unit, parameter read and write module, power amplifier operating point control and switch selection module; The combined predistortion actuator unit receives multi-channel raw digital baseband signals, performs quadrature modulation error correction based on the measured quadrature phase error, obtains multi-channel phase-corrected raw digital baseband signals, and performs combined predistortion compensation based on the bound nonlinear predistortion parameters and linear predistortion parameters to obtain compensated multi-channel digital baseband signals. The JESD204 interface module is used to receive the compensated multi-channel digital baseband signal, perform data conversion processing, and obtain the converted multi-channel digital baseband signal. The RFSoC module performs analog-to-digital conversion on the converted multi-channel digital baseband signal to obtain a multi-channel analog baseband signal; The multi-carrier transmission channel modulates the multi-channel analog baseband signal to obtain a multi-channel radio frequency modulated signal; the multi-channel radio frequency modulated signal is filtered and amplified to obtain a multi-channel power modulated signal; based on the carrier frequency of the power modulated signal, the power modulated signal of each channel is determined to be either a power modulated satellite signal or a power modulated ground signal. The first multiplexer combines all power-modulated ground signals to obtain a single ground-multi-carrier power-modulated signal. The second multiplexer combines all the power-modulated satellite signals to obtain a single satellite multi-carrier power-modulated signal; The high-speed data acquisition module performs down-conversion, analog-to-digital conversion and digital resampling on the ground multi-carrier power modulation signal to obtain a multi-channel feedback digital baseband signal. The soft-core computing unit obtains nonlinear predistortion parameters and linear predistortion parameters based on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal. The parameter read / write module is used to receive the nonlinear predistortion parameters and the linear predistortion parameters, and store them in the refresh and reconstruction unit. When in use, the linear predistortion parameters and the nonlinear predistortion parameters are bound to the joint predistortion actuator unit from the refresh and reconstruction unit according to the address index. The power amplifier operating point control and switch selection module is used to collect the solenoid current telemetry of the power amplifier of the multi-carrier transmission channel to obtain the operating point and input power backoff setting of the power amplifier; and to control the switch matrix of the multi-carrier transmission channel to select the signal output.

2. The system as described in claim 1, characterized in that, The combined predistortion actuator unit includes multiple combined predistortion actuators, each of which receives a channel of raw digital baseband signal; Each joint predistortion actuator includes a quadrature modulation error corrector (QEC), a DPD actuator module, and a linear pre-equalizer. The QEC receives the original digital baseband signal and performs quadrature modulation error correction on the phase imbalance introduced by the quadrature frequency converter in the multi-carrier transmission channel based on the measured quadrature phase error, thereby obtaining the phase-corrected original digital baseband signal. The DPD actuator module receives the phase-corrected original digital baseband signal and compensates for the strong nonlinearity and memory characteristics introduced by the power amplifier in the multi-carrier transmit channel based on the bound nonlinear predistortion parameters; the linear pre-equalizer compensates for the dispersion characteristics caused by the delay of the first multiplexer group based on the bound linear predistortion parameters.

3. The system as described in claim 2, characterized in that, The DPD actuator module includes: a CORDIC module (11); a first delay unit (1), a second delay unit (2), a third delay unit (3), a fourth delay unit (4), a fifth delay unit (5), a sixth delay unit (6), a seventh delay unit (7), an eighth delay unit (8), a ninth delay unit (9), and a tenth delay unit (10); a first RAM (12), a second RAM (13), a third RAM (14), a fourth RAM (15), a fifth RAM (16), a sixth RAM (17), a seventh RAM (18), an eighth RAM (19), a ninth RAM (20), a tenth RAM (21), an eleventh RAM (22), and a twelfth RAM (23); a first complex multiply-accumulate unit (24), a second complex multiply-accumulate unit (25), a third complex multiply-accumulate unit (26), a fourth complex multiply-accumulate unit (27); and a first accumulator (28). The read address signal ports of the first RAM (12), the second RAM (13), and the third RAM (14) are all connected to the CORDIC module (11), the read data signal ports are all connected to the first complex multiply accumulator (24), and the write address signal port and the write data signal port are connected to the parameter read and write module. The read address signal ports of the fourth RAM (15), the fifth RAM (16), and the sixth RAM (17) are all connected to the second delay unit (2), the read data signal port is connected to the second complex multiply accumulator (25), and the write address signal port and the write data signal port are connected to the parameter read and write module. The read address signal ports of the seventh RAM (18), the eighth RAM (19), and the ninth RAM (20) are connected to the fourth delay unit (4), the read data signal ports are connected to the third complex multiply accumulator (26), and the write address signal ports and write data signal ports are connected to the parameter read / write module. The read address signal ports of the tenth RAM (21), the eleventh RAM (22), and the twelfth RAM (23) are connected to the sixth delay unit (6), the read data signal ports are connected to the fourth complex multiply accumulator (27), and the write address signal ports and write data signal ports are connected to the parameter read / write module. The first accumulator (28) is connected to the output ports of the first complex multiplication accumulator (24), the second complex multiplication accumulator (25), the third complex multiplication accumulator (26), and the fourth complex multiplication accumulator (27); The first delay unit (1), the third delay unit (3), the fifth delay unit (5), the tenth delay unit (10), and the fourth complex multiply accumulator (27) are connected in sequence; The phase-corrected original digital baseband signal is input to the first delay unit (1), the CORDIC module (11), and the seventh delay unit (7), respectively.

4. The system as described in claim 2, characterized in that, The linear pre-equalizer includes: eight delay units, nine complex multipliers, and a second accumulator; The eight delay units are connected in sequence, and the output of each of the eight delay units is connected to a complex multiplier; the output of the nine complex multipliers is connected to the second accumulator. All nine complex multipliers are connected to the parameter read / write module for binding linear predistortion parameters.

5. The system as described in claim 1, characterized in that, The RFSoC module includes multiple baseband digital-to-analog converters (DACs), each including an I-branch DAC and a Q-branch DAC, which are used to perform analog-to-digital conversion on the I-component signal and the Q-component signal of the digital baseband signal, respectively.

6. The system as described in claim 1, characterized in that, The multi-carrier transmission channel includes multiple transmission channel units and a switching matrix. Each transmission channel unit includes an orthogonal frequency converter, an analog bandpass filter, a power amplifier, and an isolator. Each transmission channel unit receives an analog baseband signal from one channel. The quadrature inverter orthogonally modulates the analog baseband signal into a radio frequency modulation signal with a specific carrier frequency. The analog bandpass filter performs channel filtering on the radio frequency modulation signal. The power amplifier amplifies the power of the channel-filtered signal and then isolates the signal through the isolator to output a power modulation signal. If there is only one carrier frequency in the output multi-channel power modulation signal, then the power modulation signal corresponding to that carrier frequency is a power modulation signal to satellite. If there is more than one carrier frequency in the output multi-channel power modulation signal, then the power modulation signal corresponding to that carrier frequency is a power modulation signal to ground. The switching matrix outputs all power-modulated satellite signals to the second multiplexer and all power-modulated ground signals to the first multiplexer.

7. The system as described in claim 1, characterized in that, The high-speed data acquisition module includes a frequency conversion module, an analog-to-digital converter, and a vector signal processing module, which are used to perform down-conversion, analog-to-digital conversion, and digital resampling processing on the ground multi-carrier power modulation signal, respectively.

8. The system as described in claim 1, characterized in that, The soft-core computing unit includes a linear blind equalizer, a preprocessing module, and a joint DPD coefficient extraction module; The linear blind equalizer receives the multi-channel feedback digital baseband signal, uses the LMS algorithm to obtain the equalizer tap coefficients, and outputs the equalizer tap coefficients as linear predistortion parameters to the parameter read / write module after fixed-point quantization. The preprocessing module performs frequency deviation, phase deviation elimination, and time domain alignment processing on the multi-channel phase-corrected original digital baseband signal and the multi-channel feedback digital baseband signal, and outputs the aligned feedback digital baseband signal and the phase-corrected original digital baseband signal. The joint DPD coefficient extraction module uses the least squares method to solve for the estimated coefficient vector of DPD by matrix inversion based on the aligned feedback digital baseband signal and the phase-corrected original digital baseband signal. The estimated value is then output to the parameter read / write module as a nonlinear predistortion parameter after fixed-point quantization.

9. The system as described in claim 1, characterized in that, The refresh and reconfiguration unit includes a timed refresh chip and a Flash memory.

10. A digital predistortion compensation method, based on the spaceborne multi-carrier broadband dispersive transmission link system according to any one of claims 1-9, characterized in that, include: Step 1: Set the initial state modulation mode to where n is the modulation order; Step 2: Actual measurement of the phase imbalance error of the quadrature inverter in the multi-carrier transmission channel. The original I-branch digital baseband signal is processed. Multiply-accumulate processing is performed on the original Q-branch digital baseband signal. Multiply-accumulate processing yields the phase-corrected original digital baseband signal; Step 3: Load the initial state parameters of the linear pre-equalizer; Step 4: Collect remote measurements of the solenoid current of the power amplifier in the multi-carrier transmission channel and set the power amplifier to its actual working state; Step 5: Acquire the ground-based multi-carrier power modulation signal, perform down-conversion, analog-to-digital conversion and digital resampling processing to obtain a multi-channel feedback digital baseband signal; Step 6: Perform linear blind equalization iteration at the receiving end and use the LMS algorithm to obtain the equalizer tap coefficients; Step 7: When the error signal approaches zero, the equalizer tap coefficients are quantized at fixed point and output as linear predistortion parameters to the parameter read / write module. The parameter read / write module stores it in the refresh and reconstruction unit, completing the extraction of linear predistortion parameters and ensuring that the storage is not lost when power is off. Step 8: The parameter read / write module reads the linear predistortion parameters from the refresh and reconstruction unit, binds them to the linear preequalizer, and completes the process. Modulation mode compensation for linear distortion of satellite channels; Step 9: Perform frequency deviation, phase deviation elimination and time domain alignment processing on the original digital baseband signal after multi-channel phase correction and the multi-channel feedback digital baseband signal, and output the aligned feedback digital baseband signal and the original digital baseband signal after phase correction. Step 10: Based on the aligned feedback digital baseband signal and the phase-corrected original digital baseband signal, the coefficient vector estimate of DPD is solved by matrix inversion using the least squares method, and then output as a nonlinear predistortion parameter to the parameter read / write module after fixed-point quantization. The parameters are then stored in the refresh and reconstruction unit via the parameter read / write module, thus completing the extraction of nonlinear predistortion parameters and ensuring that the storage is not lost even when power is off.

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