An inter-satellite wideband multi-channel adaptive demodulation system and method
By using a multi-channel adaptive demodulation system within a single broadband physical channel, the problems of large equipment size, heavy weight, and high power consumption in traditional satellite communication systems have been solved. Autonomous rate judgment and adaptive demodulation have been achieved, reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN INSTITUE OF SPACE RADIO TECH
- Filing Date
- 2023-10-31
- Publication Date
- 2026-06-23
AI Technical Summary
Traditional satellite communication systems require multiple physical channels to receive multiple signals simultaneously, resulting in large equipment size, heavy weight, high power consumption, and high cost.
An inter-satellite broadband multi-channel adaptive demodulation system is adopted. By realizing multi-channel adaptive demodulation within a single broadband physical channel, the number of physical channels is reduced by utilizing a broadband receiving module, a target separation module, a frequency locking and phase locking module, a clock recovery module, a frame synchronization lock detection module, and an adaptive control module. Autonomous demodulation is achieved through an adaptive rate search method.
The device's size, weight, and power consumption have been reduced, lowering costs. At the same time, autonomous rate determination and adaptive demodulation have been achieved, simplifying the operation process.
Smart Images
Figure CN117560054B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of space communication and navigation technology, and particularly relates to an inter-satellite broadband multi-channel adaptive demodulation system and method. Background Technology
[0002] When satellites communicate with each other or with other spacecraft, they typically need to simultaneously receive communication signals from multiple other satellites or spacecraft. Traditional satellites require multiple physical channels to receive multiple communication signals simultaneously. Each physical channel is configured with a modulation scheme and data rate before receiving and demodulating the signal to achieve simultaneous communication with multiple target satellites or spacecraft. In this communication scheme, when a satellite communicates with multiple targets simultaneously, the number of physical channels required is large, resulting in a heavy satellite and increased overall power consumption. Furthermore, configuring the operating frequency, modulation scheme, and data rate for each channel on a target-by-target basis significantly increases the manpower and material costs of operation and control. Summary of the Invention
[0003] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide an inter-satellite broadband multi-channel adaptive demodulation system and method. It realizes multi-channel adaptive demodulation within a single broadband physical channel between satellites, which greatly reduces the number of physical channels, reduces the size, weight and power consumption of the equipment, and lowers the cost.
[0004] To address the aforementioned technical problems, this invention discloses an inter-satellite broadband multi-channel adaptive demodulation system, comprising: a broadband receiving module, a target separation module, N frequency-locking and phase-locking modules, N clock recovery modules, N frame synchronization lock detection modules, an adaptive control module, and N data output modules;
[0005] The output of the broadband receiver module is connected to the input of the target separation module;
[0006] The output of the target separation module is connected to the input of N frequency-locking and phase-locking modules respectively;
[0007] The output terminals of each frequency-locking and phase-locking module are connected to the input terminals of the corresponding clock recovery modules.
[0008] The output of each clock recovery module is connected to the input of the corresponding frame synchronization lock detection module and the input of the data output module, respectively.
[0009] The output of each frame synchronization lock detection module is connected to the input of the adaptive control module.
[0010] The output of the adaptive control module is connected to the input of each frequency-locking and phase-locking module, and the input of each clock recovery module, respectively.
[0011] Among them, N frequency locking and phase locking modules, N clock recovery modules, N frame synchronization lock detection modules and N data output modules form N channels; N≥2.
[0012] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system
[0013] The broadband receiving module is used to receive N target signals from N target inputs, and after bandpass filtering, power amplification, and analog-to-digital conversion of the N target signals, outputs a digital intermediate frequency signal.
[0014] The target separation module is used to perform down-conversion and low-pass filtering on the digital intermediate frequency signal input from the broadband receiving module to achieve signal separation and obtain N zero intermediate frequency signals; the N zero intermediate frequency signals are then output to N frequency-locked and phase-locked modules respectively.
[0015] The frequency-locking and phase-locking module is used to perform frequency-locking and phase-locking processing on the zero intermediate frequency signal and output a signal A with no frequency difference and no phase difference.
[0016] The clock recovery module is used to recover the clock of signal A and output the demodulated target information bits.
[0017] The frame synchronization lock detection module is used to perform frame synchronization lock detection on the demodulated target information bits; if the frame is determined to be synchronized, a frame synchronization flag is given; if the frame is determined to be out of sync, a frame out of sync flag is given.
[0018] The data output module is used to output the demodulated target information bits after the frame synchronization flag is detected;
[0019] The adaptive control module is used to perform adaptive code rate control on each channel, and to achieve adaptive switching within a known rate range.
[0020] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system, the broadband receiving module includes: a bandpass filter, a power amplifier, and an ADC;
[0021] A bandpass filter is used to receive N target signals from N target inputs, perform bandpass filtering on the N target signals to filter out interference signals, and output an intermediate frequency signal.
[0022] A power amplifier is used to amplify the power of intermediate frequency signals.
[0023] An ADC is used to perform analog-to-digital conversion on an intermediate frequency (IF) signal after power amplification, and output a digital IF signal.
[0024] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system
[0025] The bandpass filter has a 3dB passband bandwidth that covers the lowest frequency fxmin and the highest frequency fxmax of all target signals;
[0026] When a power amplifier amplifies an intermediate frequency (IF) signal, it amplifies the IF signal power to the operating range required by the ADC.
[0027] The ADC sampling rate fs satisfies the bandpass sampling theorem: 2fxmin / m≤fs≤2fxmax / (m-1); where 1≤m≤fH / B, and m is rounded down; fH represents the highest frequency of the bandpass signal, and B represents the bandpass bandwidth.
[0028] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system
[0029] When the target separation module downconverts the digital intermediate frequency signal, it downconverts the digital intermediate frequency signal to 0 frequency; the downconversion frequency point can be set and rewritten, and the initial downconversion frequency point corresponds one-to-one with the target frequency point of each target signal.
[0030] The target separation module uses a low-pass filter for low-pass filtering; the 3dB passband bandwidth of the low-pass filter is not less than the maximum value of the baseband bandwidth of all target signals.
[0031] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system, when the frequency-locking and phase-locking modules process the zero intermediate frequency signal, they square the I / Q signal, pass it through a complex multiplier to calculate the cross product, and then feed it into a second-order loop filter for loop filtering. After detecting the frequency offset value, they perform a rotation transformation to compensate for the remaining frequency difference. After frequency locking, they perform phase locking, calculate the phase error, feed it into a second-order loop filter for loop filtering, and then perform a rotation transformation to compensate for the remaining phase difference.
[0032] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system, the clock recovery module uses the early-late gate algorithm to extract signal A and sample data, recover the information bits, and obtain the demodulated target information bits.
[0033] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system, when the frame synchronization lock detection module performs frame synchronization lock detection on the demodulated target information bits, if the frame header and frame length of the demodulated target information bits for k consecutive frames meet the target information transmission characteristics, it is determined to be frame synchronized; otherwise, it is determined to be frame unsynchronized; where k≥3.
[0034] In the aforementioned inter-satellite broadband multi-channel adaptive demodulation system, when the adaptive control module performs adaptive code rate control on each channel, it searches for rates from high speed to low speed within each rate level. If the current rate cannot be synchronized within a specified time, the entire demodulation system is reset and then the next rate is used for frame synchronization determination. This process continues until a certain rate X is locked. If the lock is lost while rate X is locked, the system jumps back to the highest rate level and starts searching again.
[0035] Accordingly, this invention also discloses an inter-satellite broadband multi-channel adaptive demodulation method, comprising:
[0036] The system receives N target signals from N target inputs via a broadband receiving module. After bandpass filtering, power amplification, and analog-to-digital conversion of the N target signals, it outputs a digital intermediate frequency signal; where N≥2.
[0037] After the target separation module performs down-conversion and low-pass filtering on the digital intermediate frequency signal input to the broadband receiving module, signal separation is achieved, resulting in N zero intermediate frequency signals; the N zero intermediate frequency signals are then output to N frequency-locked and phase-locked modules respectively.
[0038] After N frequency-locking and phase-locking modules are used to process N zero intermediate frequency signals, N signals A with no frequency difference and no phase difference are output.
[0039] N clock recovery modules are used to restore the clock of N signals A respectively, and the demodulated N target information bits are output.
[0040] The frame synchronization lock detection module performs frame synchronization lock detection on each demodulated target information bit; if the frame is determined to be synchronized, a frame synchronization flag is given; if the frame is determined to be out of sync, a frame out of sync flag is given.
[0041] After recognizing the frame synchronization flags of N target information bits, each of the N data output modules outputs the corresponding demodulated target information bits.
[0042] The adaptive control module performs adaptive code rate control on each channel, achieving adaptive switching within a known rate range.
[0043] The present invention has the following advantages:
[0044] (1) This invention discloses an inter-satellite broadband multi-channel adaptive demodulation system, which performs reception, target separation and demodulation in a broadband physical channel. Compared with the traditional implementation of multiple physical channels, it greatly reduces the number of physical channels, reduces the size, weight and power consumption of the equipment, and lowers the cost.
[0045] (2) This invention discloses an inter-satellite broadband multi-channel adaptive demodulation system. Using an adaptive rate search method, it can autonomously determine the rate level of the target signal and achieve adaptive demodulation without the need for external command intervention, making it convenient and quick to use.
[0046] (3) This invention discloses an inter-satellite broadband multi-channel adaptive demodulation system. The functions of target separation, frequency locking and phase locking, clock recovery and adaptive control are easy to implement using FPGA or ASIC, and are simple to implement and highly applicable. Attached Figure Description
[0047] Figure 1 This is a structural block diagram of an inter-satellite broadband multi-channel adaptive demodulation system according to an embodiment of the present invention;
[0048] Figure 2 This is a schematic diagram of a bandpass filter for a broadband receiving module in an embodiment of the present invention;
[0049] Figure 3 This is a schematic diagram of a target separation module low-pass filtering in an embodiment of the present invention;
[0050] Figure 4 This is a schematic diagram illustrating the working principle of a clock recovery module in an embodiment of the present invention.
[0051] Figure 5 This is a flowchart of an adaptive code rate determination and control method in an embodiment of the present invention. Detailed Implementation
[0052] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed herein will be described in further detail below with reference to the accompanying drawings.
[0053] One of the core ideas of this invention is to propose an inter-satellite broadband multi-channel adaptive demodulation system for application scenarios where satellites communicate with multiple targets simultaneously. On the one hand, it can ensure the simultaneous reception and demodulation of multiple signals while reducing the number of physical channels. On the other hand, it has the feature of adaptive rate switching, which can autonomously determine the rate level of the target signal and realize adaptive demodulation without the need for external command intervention.
[0054] like Figure 1In this embodiment, the inter-satellite broadband multi-channel adaptive demodulation system includes: a broadband receiving module, a target separation module, N frequency-locked and phase-locked modules, N clock recovery modules, N frame synchronization lock detection modules, an adaptive control module, and N data output modules. The output of the broadband receiving module is connected to the input of the target separation module; the output of the target separation module is connected to the input of each of the N frequency-locked and phase-locked modules; the output of each frequency-locked and phase-locked module is connected to the input of its corresponding clock recovery module; the output of each clock recovery module is connected to the input of its corresponding frame synchronization lock detection module and the input of its corresponding data output module; the output of each frame synchronization lock detection module is connected to the input of its adaptive control module; and the output of the adaptive control module is connected to the input of each frequency-locked and phase-locked module and the input of its corresponding clock recovery module. The N frequency-locked and phase-locked modules, the N clock recovery modules, the N frame synchronization lock detection modules, and the N data output modules form N channels, where N ≥ 2.
[0055] In this embodiment, the functions of each module in the inter-satellite broadband multi-channel adaptive demodulation system are as follows:
[0056] The broadband receiver module is used to receive N target signals from N target inputs, and after bandpass filtering, power amplification, and analog-to-digital conversion of the N target signals, outputs a digital intermediate frequency signal.
[0057] In this embodiment, the broadband receiving module includes, but is not limited to, a bandpass filter, a power amplifier, and an ADC. Wherein, for example... Figure 2 As shown, a bandpass filter receives N target signals from N target inputs, performs bandpass filtering on these N signals to remove interference signals, and outputs an intermediate frequency (IF) signal. A power amplifier amplifies the IF signal. An analog-to-digital converter (ADC) performs analog-to-digital conversion on the amplified IF signal, outputting a digital IF signal.
[0058] Preferably, the bandpass filter's 3dB passband bandwidth covers the lowest frequency fxmin and the highest frequency fxmax of all target signals. When the power amplifier performs power amplification on the intermediate frequency (IF) signal, it amplifies the IF signal power to the operating range required by the ADC. The ADC sampling rate fs satisfies the bandpass sampling theorem: 2fxmin / m ≤ fs ≤ 2fxmax / (m-1), to prevent spectral aliasing; where 1 ≤ m ≤ fH / B, and m is rounded down; fH represents the highest frequency of the bandpass signal, and B represents the bandpass bandwidth.
[0059] The target separation module is used to perform down-conversion and low-pass filtering on the digital intermediate frequency signal input from the broadband receiving module to achieve signal separation and obtain N zero intermediate frequency signals; the N zero intermediate frequency signals are then output to N frequency-locked and phase-locked modules respectively.
[0060] In this embodiment, when the target separation module down-converts the digital intermediate frequency (IF) signal, it down-converts the IF signal to frequency 0. The down-conversion frequency can be rewritten through settings, and the initial down-conversion frequency corresponds one-to-one with the target frequency of each target signal. The target separation module uses a low-pass filter for low-pass filtering; the 3dB passband bandwidth of the low-pass filter is not less than the maximum value of the baseband bandwidth of all target signals.
[0061] Preferably, taking four targets (target 1, target 2, target 3, and target 4) as an example: the intermediate frequency points corresponding to target 1, target 2, target 3, and target 4 are f1, f2, f3, and f4, respectively. Sine and cosine signals for down-conversion are generated by a DDS. The frequency control words for channels 1, 2, 3, and 4 in the DDS can be set, but their initial values correspond to the center frequency f after ADC sampling, respectively. 11 f 12 f 13 f 14 The correspondence between the frequency control word and the frequency is shown in the following formula (1):
[0062] f out =(f clk / 2 b )·K···(1)
[0063] Among them, f out Corresponding to the center frequency after ADC sampling, f clk Corresponding to the sampling frequency, b represents the phase bit width, and K represents the frequency control word.
[0064] Then, digital frequency conversion is performed, multiplying the broadband signal by sine and cosine signals respectively to generate in-phase signals (I-channel) and quadrature signals (Q-channel).
[0065] Furthermore, such as Figure 3 As shown, target separation is achieved by using a low-pass filter.
[0066] The frequency-locking and phase-locking module is used to perform frequency-locking and phase-locking processing on the zero intermediate frequency signal, and output a signal A with no frequency difference and no phase difference.
[0067] In this embodiment, the frequency locking and phase locking module performs frequency locking and phase locking processing on the zero intermediate frequency signal:
[0068] Frequency locking. Squaring the I / Q signals respectively; then passing them through a complex multiplier to calculate the cross product, as shown in formula (2) below; then sending the cross product into a second-order loop filter for filtering, identifying the frequency offset value, and performing a rotation transformation to compensate for the remaining frequency difference.
[0069] IM{[I(n)+j×Q(n)]*[I(n-1)-j×Q(n-1)]}=I(n-1)×Q(n)-I(n)×Q(n-1)···(2)
[0070] Where I(n) represents the sampling data of I-channel signal and Q(n) represents the sampling data of Q-channel signal.
[0071] After frequency locking, phase locking is performed. The remaining phase difference is calculated using the I / Q signals, as shown in formula (3) below; then loop filtering is performed through a second-order loop filter; then rotation transformation is performed to compensate for the remaining phase difference.
[0072] Q′(n)×sign[I′(n)]-I′(n)×sign[Q′(n)]···(3)
[0073] Where Q′(n) represents the Q-channel sampled data after frequency discrimination, and I′(n) represents the I-channel sampled data after frequency discrimination.
[0074] The clock recovery module is used to recover the clock of signal A and output the demodulated target information bits.
[0075] In this embodiment, the clock recovery module uses the early-late gate algorithm to extract signal A and sample data, recovering the information bits and obtaining the demodulated target information bits. For example... Figure 4 As shown, energy is calculated by integrating through the leading and lagging branches respectively, and the clock error is calculated by subtraction. The clock error is then fed into a second-order loop filter for loop filtering. The filter output is then used to control the NCO overflow to adjust the sampling position. The above process is repeated until the clock is restored to lock.
[0076] The frame synchronization lock detection module is used to perform frame synchronization lock detection on the demodulated target information bits. If the frame is determined to be synchronized, a frame synchronization flag is given; if the frame is determined to be out of sync, a frame out of sync flag is given.
[0077] In this embodiment, when the frame synchronization lock detection module performs frame synchronization lock detection on the demodulated target information bits, if the frame headers and frame lengths of the demodulated target information bits for k consecutive frames satisfy the target information transmission characteristics, then it is determined to be frame synchronized and a frame synchronization identifier is given; otherwise, it is determined to be frame desynchronized and a frame desynchronization identifier is given. Wherein, k≥3.
[0078] The data output module is used to output the demodulated target information bits after the frame synchronization flag is detected.
[0079] The adaptive control module is used to perform adaptive code rate control on each channel, and to achieve adaptive switching within a known rate range.
[0080] In this embodiment, when the adaptive control module performs adaptive code rate control on each channel, it searches and traverses the rate from high speed to low speed within each rate level. If the current rate cannot be synchronized within a specified time, the entire demodulation system is reset and then the next rate is used for frame synchronization determination. This process continues until a certain rate level X is locked. If the lock is lost when rate X is locked, the system jumps back to the highest rate level and starts searching again.
[0081] Preferred, such as Figure 5 As shown, adaptive code rate status determination and control are implemented within a known rate range, divided into full-speed adaptive mode, high-speed adaptive mode, and low-speed adaptive mode:
[0082] In full-speed adaptive mode: A full-rate scan is performed across high-speed rate 1, high-speed rate 2, high-speed rate 3, low-speed rate 1, low-speed rate 2, and low-speed rate 3. The scan begins at the highest rate 1. If rate 1 locks within a specified time, the demodulation parameters are maintained at rate 1, and data is output at that rate. If rate 1 fails to lock within the specified time, the scan proceeds to high-speed rate 2. After resetting the demodulation module, the lock status is determined within a specified time at rate 2, continuing until the lowest rate 3. If the lock is lost while in a locked state, the scan returns to the highest rate in that mode and restarts the search.
[0083] In high-speed adaptive mode: a full-rate scan is performed on high-speed rates 1, 2, and 3. The scan begins at the highest rate 1. If rate 1 locks within a specified time, the demodulation parameters are maintained at rate 1, and data is output at that rate. If rate 1 fails to lock within the specified time, the scan proceeds to high-speed rate 2. After resetting the demodulation module, the lock status is determined within a specified time at rate 2, continuing until high-speed rate 3. If the lock is lost while in a locked state, the scan returns to the highest rate in that mode and restarts the search.
[0084] In low-speed adaptive mode: a full-rate scan is performed on low-speed rates 1, 2, and 3. The scan begins at low-speed rate 1. If rate 1 locks within a specified time, the demodulation parameters are maintained at rate 1, and data is output at that rate. If rate 1 fails to lock within the specified time, the scan proceeds to low-speed rate 2. After resetting the demodulation module, the lock status is determined within a specified time at rate 2, continuing until low-speed rate 3. If the lock is lost while in the locked state, the scan jumps back to the highest rate in this mode and restarts the search.
[0085] It should be noted that the target separation module, N frequency locking and phase locking modules, N clock recovery modules, N frame synchronization lock detection modules, adaptive control module, and N data output modules can be implemented based on FPGA or ASIC.
[0086] Based on the above embodiments, the present invention also discloses an inter-satellite broadband multi-channel adaptive demodulation method, comprising:
[0087] The system receives N target signals from N target inputs via a broadband receiving module. After bandpass filtering, power amplification, and analog-to-digital conversion of the N target signals, it outputs a digital intermediate frequency signal; where N≥2.
[0088] After the target separation module performs down-conversion and low-pass filtering on the digital intermediate frequency signal input to the broadband receiving module, signal separation is achieved, resulting in N zero intermediate frequency signals. The N zero intermediate frequency signals are then output to N frequency-locked and phase-locked modules respectively.
[0089] After N frequency-locking and phase-locking modules are used to process N zero-IF signals, N signals A with no frequency difference and no phase difference are output.
[0090] The clocks of N signals A are restored by N clock recovery modules, and the demodulated N target information bits are output.
[0091] The frame synchronization lock detection module performs frame synchronization lock detection on each demodulated target information bit; if the frame is determined to be synchronized, a frame synchronization flag is given; if the frame is determined to be out of sync, a frame out of sync flag is given.
[0092] After recognizing the frame synchronization flags of N target information bits, each of the N data output modules outputs the corresponding demodulated target information bits.
[0093] The adaptive control module performs adaptive code rate control on each channel, achieving adaptive switching within a known rate range.
[0094] In summary, the inter-satellite broadband multi-channel adaptive demodulation system described in this invention achieves multi-channel adaptive demodulation within a single broadband physical channel between satellites. While reducing the number of physical channels, it still ensures simultaneous reception and demodulation of multiple signals, thereby reducing the size, weight, and cost of the equipment. Furthermore, its adaptive rate switching feature allows it to autonomously determine the rate level of the target signal and achieve adaptive demodulation without the need for external command intervention, making it convenient and quick to use.
[0095] As the system implementation is in contrast to the method implementation, it is described in a simpler way. For relevant details, please refer to the description in the method implementation section.
[0096] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.
[0097] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. An inter-satellite broadband multi-channel adaptive demodulation system, characterized in that, include: The system comprises a broadband receiver module, a target separation module, N frequency-locking and phase-locking modules, N clock recovery modules, N frame synchronization lock detection modules, an adaptive control module, and N data output modules. The output of the broadband receiving module is connected to the input of the target separation module; wherein, the broadband receiving module is used to receive N target signals from N target inputs, and after bandpass filtering, power amplification, and analog-to-digital conversion of the N target signals, outputs a digital intermediate frequency signal; The output of the target separation module is connected to the input of N frequency-locked and phase-locked modules respectively; the target separation module is used to perform down-conversion and low-pass filtering on the digital intermediate frequency signal input from the broadband receiving module to achieve signal separation and obtain N zero intermediate frequency signals; the N zero intermediate frequency signals are then output to the N frequency-locked and phase-locked modules respectively. The output terminals of each frequency-locking and phase-locking module are connected to the input terminals of the corresponding clock recovery modules. The output of each clock recovery module is connected to the input of the corresponding frame synchronization lock detection module and the input of the data output module, respectively. The output of each frame synchronization lock detection module is connected to the input of the adaptive control module. The output of the adaptive control module is connected to the input of each frequency-locking and phase-locking module, and the input of each clock recovery module, respectively. The system comprises N frequency-locking and phase-locking modules, N clock recovery modules, N frame synchronization lock detection modules, and N data output modules, forming N channels. The adaptive control module performs adaptive code rate control on each channel, traversing the rate search from high to low within each rate level. If frame synchronization fails at the current rate within a specified time, the entire demodulation system is reset, and the system proceeds to the next rate for frame synchronization determination, and so on, until it locks onto a certain rate level X. If the lock is lost while rate X is locked, the system jumps back to the highest rate level and restarts the search. N ≥ 2.
2. The inter-satellite broadband multi-channel adaptive demodulation system according to claim 1, characterized in that, The frequency-locking and phase-locking module is used to perform frequency-locking and phase-locking processing on the zero intermediate frequency signal and output a signal A with no frequency difference and no phase difference. The clock recovery module is used to recover the clock of signal A and output the demodulated target information bits. The frame synchronization lock detection module is used to perform frame synchronization lock detection on the demodulated target information bits; If the frames are determined to be synchronized, a frame synchronization flag is given; if the frames are determined to be out of sync, a frame out of sync flag is given. The data output module is used to output the demodulated target information bits after the frame synchronization flag is detected; The adaptive control module is used to perform adaptive code rate control on each channel, and to achieve adaptive switching within a known rate range.
3. The inter-satellite broadband multi-channel adaptive demodulation system according to claim 2, characterized in that, The broadband receiver module includes: a bandpass filter, a power amplifier, and an ADC; A bandpass filter is used to receive N target signals from N target inputs, perform bandpass filtering on the N target signals to filter out interference signals, and output an intermediate frequency signal. A power amplifier is used to amplify the power of intermediate frequency signals. An ADC is used to perform analog-to-digital conversion on an intermediate frequency (IF) signal after power amplification, and output a digital IF signal.
4. The inter-satellite broadband multi-channel adaptive demodulation system according to claim 3, characterized in that, The bandpass filter has a 3dB passband bandwidth that covers the lowest frequency fxmin and the highest frequency fxmax of all target signals; When a power amplifier amplifies an intermediate frequency (IF) signal, it amplifies the IF signal power to the operating range required by the ADC. The ADC sampling rate fs satisfies the bandpass sampling theorem: 2fxmin / m≤fs≤2fxmax / (m-1); where 1≤m≤fH / B, and m is rounded down; fH represents the highest frequency of the bandpass signal, and B represents the bandpass bandwidth.
5. The inter-satellite broadband multi-channel adaptive demodulation system according to claim 2, characterized in that, When the target separation module downconverts the digital intermediate frequency signal, it downconverts the digital intermediate frequency signal to 0 frequency; the downconversion frequency point can be set and rewritten, and the initial downconversion frequency point corresponds one-to-one with the target frequency point of each target signal. The target separation module uses a low-pass filter for low-pass filtering; the 3dB passband bandwidth of the low-pass filter is not less than the maximum value of the baseband bandwidth of all target signals.
6. The inter-satellite broadband multi-channel adaptive demodulation system according to claim 2, characterized in that, When the frequency-locking and phase-locking module processes the zero intermediate frequency signal, it squares the I / Q signal, passes it through a complex multiplier to calculate the cross product, and then sends it to a second-order loop filter for loop filtering. After detecting the frequency offset value, it performs a rotation transformation to compensate for the remaining frequency difference. After frequency locking, it performs phase locking, calculates the phase error, sends it to a second-order loop filter for loop filtering, and then performs a rotation transformation to compensate for the remaining phase difference.
7. The inter-satellite broadband multi-channel adaptive demodulation system according to claim 2, characterized in that, The clock recovery module uses the early-late gate algorithm to extract signal A and sample data, recover the information bits, and obtain the demodulated target information bits.
8. The inter-satellite broadband multi-channel adaptive demodulation system according to claim 2, characterized in that, When the frame synchronization lock detection module performs frame synchronization lock detection on the demodulated target information bits, if the frame header and frame length of the demodulated target information bits for k consecutive frames meet the target information transmission characteristics, it is determined to be frame synchronized; otherwise, it is determined to be frame unsynchronized; where k≥3.
9. An inter-satellite broadband multi-channel adaptive demodulation method based on the inter-satellite broadband multi-channel adaptive demodulation system according to claim 1, characterized in that, include: The system receives N target signals from N target inputs via a broadband receiving module. After bandpass filtering, power amplification, and analog-to-digital conversion of the N target signals, it outputs a digital intermediate frequency signal. After the target separation module performs down-conversion and low-pass filtering on the digital intermediate frequency signal input to the broadband receiving module, signal separation is achieved, resulting in N zero intermediate frequency signals; the N zero intermediate frequency signals are then output to N frequency-locked and phase-locked modules respectively. After N frequency-locking and phase-locking modules are used to process N zero intermediate frequency signals, N signals A with no frequency difference and no phase difference are output. N clock recovery modules are used to restore the clock of N signals A respectively, and the demodulated N target information bits are output. The frame synchronization lock detection module performs frame synchronization lock detection on each demodulated target information bit. If the frames are determined to be synchronized, a frame synchronization flag is given; if the frames are determined to be out of sync, a frame out of sync flag is given. After recognizing the frame synchronization flags of N target information bits, each of the N data output modules outputs the corresponding demodulated target information bits. The adaptive control module performs adaptive code rate control on each channel, achieving adaptive switching within a known rate range.