Method and system for simulating broadband signals affected by Doppler frequency in satellite communications

Abstract

The disclosed embodiment discloses a method and system for simulating broadband signals affected by Doppler frequency in satellite communications. The method includes: sampling the received original broadband signal at the original sampling rate to obtain the signal value of the sampling point in real time; discretizing the sampling time of the original broadband signal at the original sampling rate and after being affected by the Doppler effect to obtain a discrete first time value and a second time value; storing the signal value and the first time value in parallel in multiple filter groups; triggering the filter group to perform an interpolation operation on the stored signal value based on the second time value and the first time value to obtain a signal interpolation; and frequency modulating the original broadband signal based on the carrier frequency, relative speed, and output signal interpolation to form a target signal. This method can simulate the signal conversion process through simulation technology to meet the low-cost performance testing requirements of the satellite communication system, while reducing processing time and resource consumption based on multiple filter groups.

Description

Technical Field

[0001] The present disclosure relates to the technical field of signal simulation, and in particular to a method and system for simulating broadband signals affected by Doppler frequency in satellite communications. Background Art

[0002] In the field of satellite communications, the development of communication technology has made broadband communications the mainstream. When satellites operate at high speed (such as reaching the first cosmic velocity), the Doppler effect is significant, which will cause the frequency of broadband signals to shift, seriously affecting signal demodulation and communication quality. This effect must be taken into account in the design, testing and optimization of satellite communication systems.

[0003] Traditional narrowband communications, due to their limited bandwidth, have minimal Doppler shift effects, making this effect negligible. However, wideband signals are more sensitive to this effect, and frequency offset becomes a significant issue under high-speed motion, challenging system performance. Furthermore, evaluating satellite communication system performance often requires extensive field testing, which is costly and limited by factors such as weather and equipment availability. Summary of the Invention

[0004] In view of this, the embodiments of the present disclosure provide a method for simulating broadband signals affected by Doppler frequency in satellite communications, which can simulate the signal conversion process through simulation technology, meet the low-cost performance testing requirements of satellite communication systems, and at the same time reduce processing time and resource consumption based on multiple filter groups.

[0005] In a first aspect, embodiments of the present disclosure provide a method for simulating a broadband signal affected by Doppler frequency in satellite communications, employing the following technical solutions:

[0006] Obtain the original sampling rate of the original broadband signal, the carrier frequency of the satellite, and the relative speed between the satellite and the receiving end;

[0007] receiving the original broadband signal, sampling the original broadband signal according to the original sampling rate, and obtaining signal values ​​of sampling points in real time;

[0008] Discretizing the sampling time of the original broadband signal at the original sampling rate and after being affected by the Doppler effect, respectively, to obtain a discrete first time value and a second time value;

[0009] storing the real-time acquired signal value and the first time value in parallel into a plurality of filter banks;

[0010] triggering the filter bank to perform an interpolation operation on the stored signal value based on the second time value and the first time value stored in the filter bank to obtain a signal interpolation value;

[0011] Sorting the signal interpolation according to the working timing of the plurality of filter groups, and outputting the sorted signal interpolation according to the original sampling rate;

[0012] Based on the carrier frequency, the relative speed and the output signal interpolation, the original broadband signal is frequency modulated to form a target signal, where the target signal is a broadband signal affected by the Doppler frequency.

[0013] Optionally, discretizing the sampling time of the original wideband signal at the original sampling rate and after being affected by the Doppler effect to obtain a discrete first time value and a discrete second time value includes:

[0014] When the original broadband signal is received, a first counter and a second counter are started simultaneously, wherein the counting frequency of the second counter is higher than the counting frequency of the first counter;

[0015] using the count value of the first counter to represent a discrete first time value;

[0016] Obtaining a conversion factor based on the relative speed and the speed of light;

[0017] A discrete second time value is acquired based on the count value of the second counter and the conversion factor.

[0018] Optionally, the storing the real-time acquired signal value and the first time value in parallel into a plurality of filter banks includes:

[0019] storing the real-time acquired signal values ​​in parallel in the first FIFO data buffers of the plurality of filter banks;

[0020] The first time value acquired in real time is stored in parallel in the second FIFO data buffers of the plurality of filter banks.

[0021] Optionally, triggering the filter bank to perform an interpolation operation on the stored signal value based on the second time value and the first time value stored in the filter bank to obtain a signal interpolation value includes:

[0022] extracting a start value and an operation value from the second time value;

[0023] Determine a target number according to the numbering order of the filter groups, and send the target number, the start value, and the operation value to each filter group;

[0024] When the number of the filter group is the same as the target number, triggering the filter group to compare the received start value with the earliest first time value stored in a second FIFO data buffer; wherein the second FIFO data buffer is the data buffer of the filter group;

[0025] If the comparison is consistent, a signal interpolation value is obtained based on the signal value stored in the filter bank and the received operation value.

[0026] Optionally, extracting the start value and the operation value from the second time value includes:

[0027] extracting an integer part of the second time value as a start value;

[0028] A decimal portion of the second time value is extracted as a calculation value.

[0029] Optionally, obtaining a signal interpolation value based on the signal value stored in the filter bank and the received operation value includes:

[0030] constructing a signal column vector based on the signal values ​​stored by the filter bank;

[0031] Obtaining a matrix mapping signal vector based on the signal column vector and a preset interpolation matrix;

[0032] Obtaining a decreasing exponential column vector of the operation value based on the order N of the interpolation matrix;

[0033] A signal interpolation value is obtained based on the matrix-mapped signal vector and the decreasing index column vector.

[0034] Optionally, the frequency modulating the original broadband signal based on the carrier frequency, the relative speed, and the output signal interpolation to form a target signal includes:

[0035] Obtaining a Doppler frequency based on the carrier frequency and the relative speed;

[0036] obtaining a complex signal value based on the Doppler frequency;

[0037] Obtaining a signal sample value based on the complex signal value and the output signal interpolation;

[0038] The signal sample values ​​are outputted in sequence to form a target signal.

[0039] Optionally, the method for simulating a broadband signal affected by Doppler frequency in satellite communication further includes:

[0040] Storing the startup value and the operation value in a startup value cache queue and an operation value cache queue respectively;

[0041] The start and stop of the second counter are controlled based on the remaining storage space sizes of the startup value cache queue and the operation value cache queue.

[0042] In a second aspect, the embodiments of the present disclosure further provide a broadband signal simulation system affected by Doppler frequency in satellite communications, which employs the following technical solutions:

[0043] The broadband signal simulation system affected by Doppler frequency in satellite communication includes a signal front-end processing module, multiple filter banks, a Doppler calculation module, a sequential value module, a FIFO buffer and a reset term rotation multiplier;

[0044] The input end of the signal front-end processing module is connected to the output end of the signal source;

[0045] The output end of the signal front-end processing module is connected to the input end of the Doppler calculation module and the input ends of the multiple filter groups;

[0046] The input end of the Doppler calculation module is also connected to the output end of the configuration module;

[0047] The output end of the Doppler calculation module is connected to the input ends of the multiple filter groups and the input end of the reset term rotation multiplier;

[0048] The output ends of the plurality of filter groups are connected to the input end of the sequential value taking module;

[0049] The sequential value taking module, the FIFO buffer and the reset item rotation multiplier are connected in sequence.

[0050] Optionally, the signal front-end processing module includes a signal receiver and a first counter, and the multiple filter banks each include a first FIFO data buffer and a second FIFO data buffer;

[0051] The input end of the signal receiver is connected to the output end of the signal source;

[0052] The output end of the signal receiver is connected to the input end of the first counter and the input end of the first FIFO data buffer respectively;

[0053] The output end of the first counter is connected to the input end of the second FIFO data buffer.

[0054] Optionally, the Doppler calculation module includes a second counter, a first operator, a start value cache queue, an operation value cache queue, a second operator, a direct digital frequency synthesizer and a controller, and the multiple filter banks further include a comparator and a digital signal processor;

[0055] The input end of the second counter is connected to the output end of the signal receiver, and the input end of the first operator is connected to the output end of the second counter and the output end of the configuration module;

[0056] The output end of the first operator is connected to the input end of the startup value cache queue and the input end of the calculation value cache queue, and the input end of the controller is connected to the output end of the startup value cache queue and the output end of the calculation value cache queue;

[0057] The input end of the comparator is connected to the output end of the controller and the output end of the second FIFO data buffer, and the controller is also connected to the second counter and the digital signal processor;

[0058] The input end of the digital signal processor is connected to the output end of the comparator and the output end of the first FIFO data buffer, and the output end of the digital signal processor is connected to the input end of the sequential value module;

[0059] The input end of the second operator is connected to the output end of the configuration module, and the output end of the second operator is connected to the input end of the direct digital frequency synthesizer;

[0060] An output terminal of the direct digital frequency synthesizer is connected to an input terminal of the reset term rotation multiplier.

[0061] The disclosed embodiments provide a method for simulating broadband signals affected by Doppler frequency in satellite communications. By acquiring the original sampling rate of the original signal, the satellite's carrier frequency, and the relative speed between the satellite and the receiver, the Doppler effect can be accurately incorporated into the broadband signal simulation. By acquiring signal values ​​at sampling points in real time and discretizing the sampling times of the original broadband signal at the original sampling rate and after the Doppler effect, a dynamic simulation of the Doppler effect in the time dimension is achieved. This means that the signal can be simulated as it is affected by Doppler frequency shift at different times, thereby gaining a more comprehensive understanding of the signal's changing characteristics and providing support for addressing complex situations in actual communications. The real-time acquired signal values ​​and first time values ​​are stored in parallel in multiple filter banks, leveraging the advantages of parallel processing and significantly improving data storage efficiency. Based on the second time value and the first time value stored by the filter bank, the filter bank is triggered to perform an interpolation operation on the stored signal values, accurately obtaining the signal interpolation value. After the Doppler effect, the signal sampling time changes. Interpolation can be used to obtain the appropriate signal value at the new time point, thereby ensuring signal continuity and accuracy. The signal interpolation is sorted according to the operating timing of multiple filter banks and output at the original sampling rate. This ensures the correct order of the output signal interpolation, avoiding signal confusion and distortion. Based on the carrier frequency, relative velocity, and the output signal interpolation, the original wideband signal is frequency modulated to form a wideband signal affected by the Doppler frequency. This frequency modulation method accurately reflects the Doppler effect in the target signal, making the generated target signal more consistent with the signal characteristics used in actual satellite communications. The generated target signal can be used to evaluate and test the performance of satellite communication systems. For example, by analyzing the target signal's bit error rate, signal-to-noise ratio, and other indicators, the system's performance under the influence of the Doppler effect can be evaluated, providing a basis for system optimization and improvement.

[0062] The above description is only an overview of the technical solution of the present disclosure. In order to more clearly understand the technical means of the present disclosure, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present disclosure more obvious and easy to understand, the following specifically cites preferred embodiments and describes them in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0064] Figure 1A schematic flow chart of a method for simulating a broadband signal affected by Doppler frequency in satellite communications provided by an embodiment of the present disclosure;

[0065] Figure 2 A schematic diagram of a signal modulation circuit provided in an embodiment of the present disclosure;

[0066] Figure 3 A schematic diagram of a process for discretizing sampling time provided in an embodiment of the present disclosure;

[0067] Figure 4 A schematic diagram of a flow chart of a parallel storage method provided in an embodiment of the present disclosure;

[0068] Figure 5 A flowchart of a filter bank control method provided by an embodiment of the present disclosure;

[0069] Figure 6 A flow chart of a signal interpolation calculation method provided in an embodiment of the present disclosure;

[0070] Figure 7 A schematic flow chart of a target signal forming method provided in an embodiment of the present disclosure;

[0071] Figure 8 The time-frequency diagram of the original broadband signal provided by the embodiment of the present disclosure;

[0072] Figure 9 A time-frequency diagram of a target signal provided by an embodiment of the present disclosure;

[0073] Figure 10 A phase difference diagram provided for an embodiment of the present disclosure; DETAILED DESCRIPTION

[0074] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0075] It should be clear that the following embodiments of the present disclosure are described through specific concrete examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other in the absence of conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0076] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0077] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure. The illustrations only show components related to the present disclosure and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0078] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described can be practiced without these specific details.

[0079] Reference Figure 1 The present disclosure provides a method for simulating a broadband signal affected by Doppler frequency in satellite communications, comprising the following steps:

[0080] S1: Obtain the original sampling rate of the original broadband signal, the satellite's carrier frequency, and the relative speed between the satellite and the receiver;

[0081] S2: Receive the original broadband signal, sample the original broadband signal according to the original sampling rate, and obtain the signal value of the sampling point in real time;

[0082] S3: discretizing the sampling time of the original broadband signal at the original sampling rate and after being affected by the Doppler effect, respectively, to obtain a discrete first time value and a discrete second time value;

[0083] S4: storing the real-time acquired signal value and the first time value in parallel into a plurality of filter banks;

[0084] S5: Based on the second time value and the first time value stored in the filter bank, trigger the filter bank to perform an interpolation operation on the stored signal value to obtain a signal interpolation value;

[0085] S6: Sort the signal interpolation according to the working sequence of the multiple filter groups, and output the sorted signal interpolation according to the original sampling rate;

[0086] S7: Based on the carrier frequency, the relative speed and the output signal interpolation, the original broadband signal is frequency modulated to form a target signal, which is a broadband signal affected by the Doppler frequency.

[0087] The present disclosure provides a method for simulating broadband signals affected by Doppler frequency in satellite communications. By obtaining the original sampling rate of the original signal, the carrier frequency of the satellite, and the relative speed between the satellite and the receiving end, the Doppler effect can be accurately incorporated into the broadband signal simulation. In satellite communications, due to the relative motion between the satellite and the receiving end, Doppler frequency shift occurs, which has a significant impact on the transmission and reception of signals. This method takes these key factors into account, making the simulation results more consistent with actual satellite communication scenarios and providing more reliable data for subsequent system design and performance evaluation. By obtaining the signal values ​​of the sampling points in real time and discretizing the sampling times of the original broadband signal at the original sampling rate and after being affected by the Doppler effect, a dynamic simulation of the Doppler effect in the time dimension is achieved. This means that the situation in which the signal is affected by the Doppler frequency shift at different times can be simulated, thereby more comprehensively understanding the changing characteristics of the signal and providing support for dealing with complex situations in actual communications.

[0088] Storing the real-time signal values ​​and first-time values ​​in parallel across multiple filter banks leverages the advantages of parallel processing, significantly improving data storage efficiency. When processing broadband signals, data volumes are typically large. Using serial storage can slow processing and even lead to data backlogs. Parallel storage, however, fully utilizes the resources of multiple filter banks, accelerating data storage and ensuring the system can process large amounts of signal data in real time.

[0089] Based on the second time value and the first time value stored by the filter bank, the filter bank is triggered to perform an interpolation operation on the stored signal value, accurately obtaining the signal interpolation. Due to the Doppler effect, the sampling time of the signal changes. Through interpolation, the appropriate signal value can be obtained at the new time point, thus ensuring the continuity and accuracy of the signal. This interpolation processing method is highly flexible and can be adjusted to different simulation requirements and scenarios. For example, the degree of influence of the Doppler effect varies under different satellite motion states. By adjusting the interpolation algorithm and parameters, it can better adapt to various complex situations and improve the accuracy and reliability of the simulation.

[0090] The interpolated signals are sorted according to the operating timing of multiple filter banks and then output at the original sampling rate. This ensures the correct order of the output interpolated signals, avoiding signal confusion and distortion. In practical satellite communication systems, the correct order of signals is crucial for subsequent demodulation and decoding. This method ensures signal integrity through sorting operations. Outputting the interpolated signals at the original sampling rate ensures that the output signal has the same sampling rate as the original wideband signal, facilitating compatibility and integration with subsequent systems. This reduces additional sampling rate conversion operations, reducing system complexity and processing costs.

[0091] Based on the carrier frequency, relative velocity, and output signal interpolation, the original broadband signal is frequency modulated to generate a broadband signal affected by the Doppler frequency. This frequency modulation method accurately reflects the Doppler effect in the target signal, making the generated target signal more consistent with the signal characteristics of actual satellite communications. The generated target signal can be used to evaluate and test the performance of satellite communication systems. For example, by analyzing the target signal's bit error rate, signal-to-noise ratio, and other indicators, the system's performance under the influence of the Doppler effect can be evaluated, providing a basis for system optimization and improvement.

[0092] In S1, users can manually enter the original broadband signal's original sampling rate, the satellite's carrier frequency, and the relative speed between the satellite and the receiver through the configuration module interface. The configuration module then transmits these data to subsequent modules for calculation. The receiver refers to the device that receives the target signal.

[0093] In S2, a signal receiver is set up to receive the original wideband signal output by the signal source. The original sampling rate of the original wideband signal is the input sampling rate. At this point, the original wideband signal has not yet been affected by the Doppler effect and does not meet the testing requirements of satellite communications. Therefore, the original wideband signal is frequency modulated to add the Doppler effect to the signal and complete the Doppler signal simulation. Before adjustment, the signal receiver samples the original wideband signal at the original sampling rate, obtains sampling points in real time, and records the signal values ​​at these sampling points in bits. These recorded signal values ​​serve as the basis for subsequent interpolation operations.

[0094] Reference Figure 2 The signal modulation circuit schematic is shown. By optimizing the signal processing architecture inside the field programmable gate array (FPGA), the signal simulation mechanism is optimized. Sig_in represents the original broadband signal emitted by the signal source, and SR represents the signal receiver. SR is responsible for receiving Sig_in and sampling it according to the original sampling rate, and then outputting the signal values ​​of these sampling points, which are recorded as 、 、…、 、…。

[0095] In S3, the core goal of signal simulation is to achieve the sampling rate conversion of the original broadband signal, that is, to convert the original broadband signal at the original sampling rate into a broadband signal with Doppler frequency shift characteristics by simulating the influence of Doppler frequency. This process requires clarifying the time point corresponding to the original broadband signal under the original sampling rate conditions, as well as the time point corresponding to the signal after being affected by the Doppler effect. Discretization is the key process of converting continuous-time signals into discrete-time signals. Through discretization, the discrete time points of the original broadband signal at the original sampling rate and after being affected by the Doppler effect can be clearly determined, thereby providing the necessary foundation for the signal conversion process. Figure 3 The flowchart of sampling time discretization is shown, which includes the following steps: "Discretizing the sampling time of the original broadband signal at the original sampling rate and after being affected by the Doppler effect to obtain a discrete first time value and a discrete second time value."

[0096] S31: when the original broadband signal is received, starting the first counter and the second counter simultaneously, wherein the counting frequency of the second counter is higher than the counting frequency of the first counter;

[0097] S32: using the count value of the first counter to represent a discrete first time value;

[0098] S33: Obtain conversion factor based on relative velocity and speed of light;

[0099] S34: Acquire a discrete second time value based on the count value of the second counter and the conversion factor.

[0100] In the above steps, receiving the original wideband signal is a trigger point, at which point the first counter and the second counter are simultaneously activated. The count value of the first counter represents the sampling time points of the original wideband signal after being discretized at the original sampling rate, recorded as first time values. These first time values ​​constitute the normalized time axis of the original wideband signal. The count value of the second counter represents the sampling time points of the original wideband signal after being discretized by the Doppler effect, recorded as second time values. These second time values ​​constitute the normalized time axis of the original wideband signal (i.e., the target signal) after being affected by the Doppler effect.

[0101] Because the Doppler effect changes the spectrum of the original broadband signal, thereby affecting the phase and time characteristics of the original broadband signal, there will be a time difference between the signal affected by the Doppler effect and the original broadband signal. In order to accurately compare and process the original broadband signal and the signal affected by the Doppler effect, the two need to be aligned in time, which is usually achieved with the help of interpolation operations. In order to facilitate the completion of the interpolation operation, the time resolution after the interpolation operation can be made higher, that is, the time points after discretization need to be denser. This requires that the counting frequency of the second counter is higher than the counting frequency of the first counter, so that the rate at which the second counter generates time axis marks is greater than that of the first counter, thereby obtaining more precise time discrete values ​​and providing a better time reference for accurate interpolation. For example, if the counting frequency of the first counter is 100MHz, the counting frequency of the second counter can be set to 400MHz.

[0102] The second time value is equal to the product of the count value of the second counter and the conversion factor. The conversion factor refers to the proportional factor of compression and stretching of the original broadband signal under high-speed motion. The calculation formula of the second time value is as follows:

[0103] ;(Formula 1)

[0104] In formula 1, is a time series index of the target signal, used to mark the order of each count of the second counter and the order of generating the second time value; For the A second time value; The first count values; is the conversion factor, is the ratio between the relative velocity and the speed of light, that is , is the relative speed; The speed of light.

[0105] Reference Figure 2 , CNT1 represents the first counter, CNT1 is connected to the signal receiver SR, and is used to bind the output of Sig_in, and CNT2 represents the second counter. When SR receives the original broadband signal, it sends a start instruction to CNT1 and CNT2. After receiving the start instruction, the first counter and the second counter start counting according to their respective frequencies. The first counter generates a first time value in real time, which is recorded as 、 、…、 ,…. CNT1 and SR together constitute the signal front-end processing module, which is Figure 2It is represented as FE, which is used to receive and process the original broadband signal and output the signal value of the sampling point and the corresponding first time value The count value generated by the second counter is recorded as 、 、…、 , ..., AU1 represents a first operator, which is used to generate a count value according to the second counter And configure the relative speed of the module output , calculate the second time value.

[0106] To accurately process and analyze the original wideband signal at the original sampling rate while accounting for changes in signal characteristics due to the Doppler effect, it is necessary to align the time points of the signal at the original sampling rate with the equivalent time points of the signal after the Doppler effect. The auto-increment function of the first and second counters is used to discretize time, generating discretized first and second time values. These discretized first and second time values ​​provide the basis for this signal time point alignment, allowing comparison and processing of the original wideband signal at the original sampling rate with the corresponding time points of the signal after the Doppler effect (although the signal frequency has changed due to the effect, they can still be linked through the time correspondence). Furthermore, the discretized signal and time values ​​enhance signal processing flexibility. In digital signal processing systems, these discrete values ​​can be efficiently stored and processed, supporting a variety of complex signal processing algorithms. This provides a powerful foundation for accurate analysis of wideband signal characteristics affected by the Doppler effect and precise target detection and location, among other applications.

[0107] In S4, refer to Figure 4 The flowchart of the parallel storage method shown in the figure, "Parallel storage of real-time acquired signal values ​​and first time values ​​into multiple filter banks" includes the following steps:

[0108] S41: storing the real-time acquired signal values ​​in parallel into the first FIFO data buffers of the plurality of filter banks;

[0109] S42: The first time value acquired in real time is stored in parallel in the second FIFO data buffers of the plurality of filter banks.

[0110] In the above steps, refer to Figure 2 , multiple filter groups are pre-set, and these filter groups complete the interpolation operation of the signal value in parallel, thereby improving the conversion speed of the original broadband signal. The number of filter groups can be freely adjusted according to the FPGA resources, and each filter group has its own number, such as FB1, FB2, ..., FB h 、…、FB H , where h is the number and H is the total number of filter banks.

[0111] In order to facilitate each filter to process the signal value in time according to the time point, the signal value and the corresponding first time value need to be stored in parallel in the corresponding FIFO data buffer (First-In-First-Out Data Buffer). Each filter group includes two FIFO data buffers with first-in-first-out characteristics. When the data is full, if there is new data, the earliest stored data (at the head of the data queue) will be moved out, and then the new data will be stored at the tail of the data queue. One of the FIFO data buffers is used to store the signal value, recorded as the first FIFO data buffer; the other is used to store the first time value, recorded as the second FIFO data buffer. Figure 2 In FIG, Buffer1 represents the first FIFO data buffer, and Buffer2 represents the second FIFO data buffer.

[0112] The method of storing the real-time acquired signal value and the first time value in parallel in each filter bank can, on the one hand, facilitate subsequent interpolation operations. The storage can establish a corresponding relationship between the signal value and the first time value, which is conducive to accurate interpolation based on the time point at the original sampling rate. The filter bank characteristics can also be used to interpolate the stored signal in a targeted manner, improving accuracy and efficiency. On the other hand, it helps to achieve parallel processing and improve efficiency. Multiple filter banks working in parallel can give full play to the advantages of parallel processing, shorten signal conversion time, and meet real-time signal processing requirements. In addition, it also facilitates the sorting and output of signal interpolation, provides a unified data source for sorting, adapts to the differences in the working timing of different filter banks, and ensures that when the original broadband signal is frequency modulated based on the carrier frequency, relative speed, and output signal interpolation, the target signal affected by the Doppler frequency is smoothly formed, ensuring the stability and accuracy of the target signal output.

[0113] In S5, refer to Figure 5 The flowchart of the filter bank control method shown in the figure, "triggering the filter bank to perform an interpolation operation on the stored signal value based on the second time value and the first time value stored in the filter bank to obtain a signal interpolation value" includes the following steps:

[0114] S51: extracting a start value and an operation value from the second time value;

[0115] S52: Determine the target number according to the order of the filter groups, and send the target number, the start value, and the operation value to each filter group;

[0116] S53: When the filter group number is the same as the target number, the filter group is triggered to compare the received start value with the first time value stored earliest in the second FIFO data buffer; if the comparison is consistent, S54 is executed; if the comparison is inconsistent, S55 is executed;

[0117] S54: Obtaining a signal interpolation value based on the signal value stored in the filter bank and the received operation value;

[0118] S55: The task of not triggering interpolation operation.

[0119] In the above steps, the start value is used to trigger the filter bank to begin interpolation operations, while the run value is used in conjunction with the corresponding signal value to participate in the specific interpolation operation. First, the second time value is processed and split into an integer portion and a decimal portion, with the integer portion serving as the start value and the decimal portion serving as the run value. Next, the target numbers are determined sequentially, starting with the smallest filter bank number and setting it as the first target number. Subsequently, the extracted start value, run value, and target number are transmitted to each filter bank via a data transmission channel. Upon receiving the target number, each filter bank checks whether its own number matches the received target number. If the filter bank number matches the target number, the filter bank reads the oldest stored first time value from its second FIFO data buffer. Due to the first-in, first-out nature of the second FIFO data buffer, the oldest stored first time value is located at the beginning of the buffer. The start value received by the filter bank is then compared with the read first time value. If the comparison is consistent, it means that the current time point has met the triggering conditions for the filter bank to perform interpolation operations. At this time, the filter bank can be triggered to perform interpolation operations on the signal values ​​stored in the first FIFO data buffer. In other words, the filter bank will calculate the signal interpolation value according to the preset interpolation algorithm based on the received operation value and the stored signal value. If the comparison is inconsistent, it means that the current time point has not yet met the requirements for the filter bank to perform interpolation operations. At this time, the filter bank interpolation operation task is not triggered.

[0120] Reference Figure 2 , the first operator AU1 and the counter CNT2 are part of the Doppler calculation module, which is used to control each filter group to perform interpolation operations. The module also includes a controller, which is represented by CTRL, and the Doppler calculation module is represented by SRC. After calculating the second time value, the first operator AU1 extracts the start value and the operation value from it, Int represents the start value, and frac represents the operation value. For example, when the second time values ​​are [0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5], the extracted start values ​​are Int = [0, 0, 1, 1, 2, 2, 3, 3], and the operation values ​​are frac = [0, 0.5, 0, 0.5, 0, 0.5, 0, 0.5]. CTRL determines the target number according to the numbering order of the filter group. Figure 2In the Target, the target number is represented by Target. For example, the initial value of Target is number 1, and then it changes to number 2, number 3, and finally number H. After all numbers are traversed, polling will continue, starting again from number 1.

[0121] Each filter bank includes a comparator and a digital signal processor. Figure 2 In the figure, the comparator is represented by CMP, and the digital signal processor is represented by DSP. CTRL sends Int and Target to the CMP of each filter bank, and frac to the DSP of each filter bank. After receiving this data, the CMP compares the filter bank number with the result of Target. This triggers a comparison between Int and the earliest first time value stored in the second FIFO data buffer Buffer2 of the filter bank. When both comparisons meet the conditions, the interpolation operation for the filter bank is started. At this time, the CMP sends a calculation instruction to the DSP, which, upon receiving the calculation instruction, begins the interpolation operation using frac.

[0122] Furthermore, the counting frequency of the second counter is relatively high, which makes the real-time generation speed of the second time value relatively fast. In order to process the generated second time value in a timely manner, a startup value cache queue and an operation value cache queue are configured in the Doppler calculation module, wherein the startup value cache queue is used to store the generated startup value, and the operation value cache queue is used to store the generated operation value. The remaining storage space size of the startup value cache queue and the operation value cache queue is monitored in real time. When the remaining storage space size of any cache queue is lower than the first threshold, it means that the cache queue is about to be full, and the counting operation of the second counter is suspended. The remaining storage space size of the cache queue continues to be monitored. When the remaining storage space size is higher than the second threshold, it indicates that the cache queue has released enough space and the second counter is restarted. When the remaining storage space size of any cache queue is higher than the third threshold, it means that the buffered data in the cache queue is about to be used up, and the counting frequency of the second counter needs to be accelerated.

[0123] exist Figure 2 In the figure, BQ1 represents the startup value cache queue, and BQ2 represents the calculation value cache queue. CTRL not only extracts Int and frac from BQ1 and BQ2 respectively, but also monitors the remaining storage space of BQ1 and BQ2 in real time, and controls the start and stop of the second counter based on the remaining storage space of the two.

[0124] By configuring the startup value cache queue and the calculation value cache queue to promptly process the frequently generated startup values ​​and calculation values, and monitoring the remaining storage space of the cache queue in real time, the counting is paused to prevent overflow when the value is below the first threshold, and the counting is restarted to ensure continuity when the value is above the second threshold. When the value is above the third threshold, the counting frequency is accelerated to dynamically respond to the situation where the buffered data is about to run out, which can improve data processing efficiency, stability and flexibility.

[0125] When the filter group is triggered to perform interpolation operation, the filter group starts to calculate the signal interpolation. Figure 6 The flowchart of the signal interpolation calculation method shown in the figure "Obtaining a signal interpolation value based on the signal value stored in the filter bank and the received operation value" includes the following steps:

[0126] S541: Constructing a signal column vector based on the signal values ​​stored in the filter bank;

[0127] S542: Obtain a matrix mapping signal vector based on the signal column vector and a preset interpolation matrix;

[0128] S543: Obtaining a decreasing exponential column vector of the operation value based on the order N of the interpolation matrix;

[0129] S544: Obtain signal interpolation based on the matrix mapping signal vector and the decreasing index column vector.

[0130] In the above steps, the interpolation matrix is ​​a matrix with N rows and N columns. The number of storage units of Buffer1 and Buffer2 is set to be equal to the order N, so that the number of signal values ​​stored by the filter bank and the number of first time values ​​are always N. This not only facilitates the alignment of the signal value with the first time value, but also helps in the subsequent calculation of the signal value stored by the filter bank and the interpolation matrix. First, the signal value stored by the filter bank is constructed as a signal column vector. The expression of the signal column vector is as follows:

[0131] ;(Formula 2)

[0132] In formula 2, is the time series index of the original width signal, which is used to mark the generation order of the signal value. The order of the marked signal value is consistent with the order of each count of the first counter. At the same time, the order of each count of the first counter is also the generation order of the first time value. is the signal column vector; For the signal values; is the transpose of the matrix.

[0133] The interpolation matrix can be generated by various methods such as the sinc method (Single function method) and the Lagrange method. The general expression of the interpolation matrix is ​​as follows:

[0134] ;(Formula 3)

[0135] In formula 3, is the interpolation matrix, … is the element value of the interpolation matrix.

[0136] Taking the Lagrange method as an example, construct an interpolation matrix of N=4, and for each interpolation point and , calculate the polynomial coefficients through the Lagrange interpolation polynomial, where, , , the expression of the Lagrange interpolation polynomial is as follows:

[0137] ;(Formula 4)

[0138] In formula 4, is the independent variable; is the Lagrangian basis function.

[0139] Substitute into formula 4 value, calculated 、 、 、 The polynomial coefficients of , these polynomial coefficients form a coefficient matrix, the expression of the coefficient matrix is ​​as follows:

[0140] ;(Formula 5)

[0141] In formula 5, is the coefficient matrix.

[0142] The calculation results of the interpolation matrix are as follows:

[0143] ;(Formula 6)

[0144] Multiply the signal column vector by the interpolation matrix to obtain an N+1-order matrix-mapped signal vector. Calculate the decreasing exponent column vectors of the operation values ​​according to the matrix order N. The elements in the decreasing exponent column vectors are the powers of the operation values, and the powers decrease from N−1 to 0. The expression of the decreasing exponent column vector is as follows:

[0145] ;(Formula 7)

[0146] In formula 7, is a column vector of decreasing exponents.

[0147] The decreasing exponential column vector is transposed and multiplied with the matrix mapping signal vector, and then the sum is obtained to obtain the signal interpolation. The calculation formula of the signal interpolation is as follows:

[0148] ;(Formula 8)

[0149] In formula 8, For the Signal interpolation calculated by filter banks; Maps the signal vector to the matrix.

[0150] Reference Figure 2 The digital signal processor DSP reads signal values ​​from the first FIFO data buffer Buffer1, constructs a signal column vector from the read signal values, and then calculates the signal interpolation value by combining it with the operation value frac sent by the controller CTRL. The row vector composed of the extracted operation values ​​can be compared to a time axis, and the calculated signal interpolation values ​​are equivalent to the signal sampling values ​​corresponding to each time point on this time axis. For example, assuming that the starting value calculated by the Doppler calculation module is 24, the input signal flows through the filter bank FB1 sequentially. When the first time value of 24 is stored, the condition is triggered and the difference operation begins. The calculation result is output as: 0.4677 + 0.8839i, which is sent to the FIFO buffer and output according to the original sampling rate of 100Mhz.

[0151] In S6, the filter banks execute their operations sequentially according to their numbering order. Therefore, the operating timing of the filter banks is determined by the numbering order. The filter bank numbers corresponding to the signal interpolation are sorted in ascending order. The signal interpolation is stored in the FIFO buffer according to this sorting order. The field programmable gate array outputs the sorted signal interpolation in the FIFO buffer at the original sampling rate.

[0152] Reference Figure 2 , SVM represents the sequential value module, FIFOCache represents the FIFO buffer, SVM is responsible for arranging the filter group numbers corresponding to the signal interpolation in ascending order, and storing the signal interpolation in FIFOCache according to the sorting order. By this method, it can ensure that the field programmable gate array can correctly output the order of signal interpolation. The output order of FIFOCache for signal interpolation from front to back is 、…、 、…、 、 、…、 、…。

[0153] In S7, refer to Figure 7The flow chart of the target signal formation method is shown. "Based on the carrier frequency, relative speed, and output signal interpolation, the original broadband signal is frequency modulated to form the target signal." The method includes the following steps:

[0154] S71: Obtaining Doppler frequency based on carrier frequency and relative speed;

[0155] S72: Acquire a complex signal value based on the Doppler frequency;

[0156] S73: Obtaining a signal sample value based on the complex signal value and the output signal interpolation;

[0157] S74: Output signal sample values ​​in sequence to form a target signal.

[0158] In the above steps, the Doppler calculation module is also used to calculate the complex signal value and transmit it to the reset term rotation multiplier, wherein the complex signal is a signal expressed in complex form, which can simultaneously reflect the amplitude and phase information of the signal, and its frequency is the same as the Doppler frequency. In the process of continuously generating complex signals, each exact time point corresponds to a specific value of the complex signal. This value is the complex signal value, which changes with time. Every time the FIFO buffer outputs a signal interpolation, the reset term rotation multiplier multiplies the signal interpolation with the received complex signal value to obtain the corresponding signal sample value. These signal sample values ​​are output in sequence according to the output order of the signal interpolation, and these signal sample values ​​output in sequence together form the target signal affected by the Doppler frequency.

[0159] The calculation formula of Doppler frequency is as follows:

[0160] ;(Formula 9)

[0161] In formula 9, is the Doppler frequency; is the carrier frequency.

[0162] The Doppler calculation module also includes a second operator and a digital frequency synthesizer (Direct Digital Synthesizer). Figure 2 In the equation, AU2 represents the second operator, DDS represents the digital frequency synthesizer, RTRM represents the reset term rotation multiplier, and s(t) represents the complex signal value at the tth moment. The second operator is based on the carrier frequency output by the configuration module. and relative speed , calculate the Doppler frequency , DDS generates a complex signal based on the Doppler frequency and outputs s(t), and RTRM combines s(t) with Multiply, get and output the signal sample value, the output order of the signal sample value from front to back is 、…、 、…、 、 、…、 ,…, these sequentially output signal sample values ​​form the target signal.

[0163] In summary, the Doppler calculation module precisely controls the filter bank calculation process based on the original sampling rate of the original broadband signal and the relative speed between the signal source and the receiver. Assuming four filter banks are configured, when data from each sampling point arrives, the filter bank combinations involved may be [1], [1,2], [1,2,3], or [1,2,3,4]. This means that the number of activated filter banks changes in real time with the amount of data. Each filter bank operates according to the instructions issued by the Doppler calculation module and calculates signal interpolation. The output results of filter banks 1-4 may appear as [O1], [O1,O2], [O1, O2,O3], or [O1, O2,O3,O4]. These calculated signal interpolations are sent to the sequential evaluation module for sorting. In this way, the FPGA can simultaneously utilize multiple filter banks to complete signal interpolation, accelerating signal processing. Moreover, when the original sampling rate or other related parameters of the original broadband signal change, this method can still effectively introduce the influence of Doppler frequency into the original broadband signal, thereby improving the flexibility of signal conversion and enabling simulation tasks to more accurately and efficiently simulate actual scenarios affected by Doppler frequency in satellite communications, providing a more reliable basis for the design, testing and optimization of satellite communication systems.

[0164] Taking the original sampling rate of 1200MHz as an example, a broadband swept frequency complex signal with a bandwidth of 240MHz is constructed and used as the original broadband signal. The duration and idle time of the original broadband signal are both set to 1×10⁻ 5 Sec. Reference Figure 8 The original broadband signal time-frequency diagram and Figure 9 The target signal time-frequency diagram shown analyzes the Doppler effect at different relative speeds during the signal conversion process through four filter banks. In the extreme case, when the relative speed of the two satellites reaches 2×7900=15800m / s (i.e., twice the first cosmic velocity), the Doppler effect is present, but because this speed is extremely small compared to the speed of light, its impact is not significant. However, when the relative speed is increased to 0.6c (c is the speed of light in a vacuum, approximately 3×10 8 m / s, 0.6c is 1.8×10 8m / s), the conversion factor is 2, and the Doppler effect causes significant signal compression. Specifically, the length of the Doppler-compressed signal is halved, while the bandwidth of the original wideband signal is doubled and the time is halved. This result fully meets simulation expectations.

[0165] Fix the relative speed to 2 times the first cosmic speed, keep other parameters unchanged, refer to Figure 10 The phase difference diagram between the original broadband signal and the target signal shows that the original broadband signal and the target signal maintain phase consistency at the beginning of the simulation. However, towards the end of the simulation, a phase difference of -22° develops between the two. This phenomenon clearly demonstrates that this simulation method can accurately reflect the Doppler effect on broadband signals at high speeds, providing good simulation results and reliability, making it suitable for simulating broadband Doppler signals at the first cosmic velocity.

[0166] Reference Figure 2 , the present disclosure provides a broadband signal simulation system affected by Doppler frequency in satellite communications, comprising a signal front-end processing module, multiple filter banks, a Doppler calculation module, a sequential value module, a FIFO buffer and a reset term rotation multiplier;

[0167] The input end of the signal front-end processing module is connected to the output end of the signal source;

[0168] The output end of the signal front-end processing module is connected to the input end of the Doppler calculation module and the input ends of the plurality of filter groups;

[0169] The input end of the Doppler calculation module is also connected to the output end of the configuration module;

[0170] The output end of the Doppler calculation module is connected to the input ends of the plurality of filter banks and the input end of the reset term rotation multiplier;

[0171] The output ends of the plurality of filter banks are connected to the input ends of the sequential value taking modules;

[0172] The sequential value module, the FIFO buffer and the reset item rotation multiplier are connected in sequence.

[0173] The Doppler calculation module receives the original sampling rate of the original signal sent by the configuration module, the carrier frequency of the satellite, and the relative speed between the satellite and the receiving end; the signal front-end processing module receives the original signal transmitted by the signal source, samples the original signal according to the original sampling rate, obtains the signal value of the sampling point in real time, and discretizes the sampling time of the original signal at the original sampling rate to obtain a discrete first time value, and stores the real-time obtained signal value and the first time value in parallel in multiple filter groups;

[0174] The Doppler calculation module discretizes the sampling time of the original signal after being affected by the Doppler effect to obtain a discrete second time value, and triggers the filter bank to perform an interpolation operation on the stored signal value based on the second time value and the first time value stored in the filter bank to obtain a signal interpolation value;

[0175] The sequential value module sorts the signal interpolation according to the working sequence of multiple filter groups, stores the signal interpolation in the FIFO buffer in the sorted order, and the field programmable gate array outputs the sorted signal interpolation in the FIFO buffer according to the target sampling rate;

[0176] The Doppler calculation module obtains the Doppler frequency based on the carrier frequency and the relative speed, and obtains the complex signal value based on the Doppler frequency; the reset term rotation multiplier obtains the signal sample value based on the complex signal value and the output signal interpolation; and the signal sample values ​​are output in sequence to form the target signal.

[0177] Furthermore, the signal front-end processing module includes a signal receiver and a first counter, and the plurality of filter banks each include a first FIFO data buffer and a second FIFO data buffer;

[0178] The input end of the signal receiver is connected to the output end of the signal source;

[0179] The output end of the signal receiver is connected to the input end of the first counter and the input end of the first FIFO data buffer respectively;

[0180] The output end of the first counter is connected to the input end of the second FIFO data buffer.

[0181] In which, when the signal receiver receives the original signal, the first counter is controlled to start counting, and the count value of the first counter is used to represent the discrete first time value. At the same time, the signal receiver obtains the signal value of the sampling point in real time through the original sampling rate; the real-time obtained signal value is stored in parallel in the first FIFO data buffer of multiple filter groups; the real-time obtained first time value is stored in parallel in the second FIFO data buffer of multiple filter groups.

[0182] Furthermore, the Doppler calculation module includes a second counter, a first operator, a start value cache queue, an operation value cache queue, a second operator, a direct digital frequency synthesizer and a controller, and the plurality of filter banks also include a comparator and a digital signal processor;

[0183] The input end of the second counter is connected to the output end of the signal receiver, and the input end of the first operator is connected to the output end of the second counter and the output end of the configuration module;

[0184] The output end of the first operator is connected to the input end of the startup value cache queue and the input end of the calculation value cache queue, and the input end of the controller is connected to the output end of the startup value cache queue and the output end of the calculation value cache queue;

[0185] The input end of the comparator is connected to the output end of the controller and the output end of the second FIFO data buffer, and the controller is also connected to the second counter and the digital signal processor;

[0186] The input end of the digital signal processor is connected to the output end of the comparator and the output end of the first FIFO data buffer, and the output end of the digital signal processor is connected to the input end of the sequential value module;

[0187] The input end of the second operator is connected to the output end of the configuration module, and the output end of the second operator is connected to the input end of the direct digital frequency synthesizer;

[0188] An output terminal of the direct digital frequency synthesizer is connected to an input terminal of the reset term rotation multiplier.

[0189] When the signal receiver receives the original signal, the second counter is controlled to start counting; the first operator obtains the conversion factor according to the relative speed output by the configuration module, and obtains the discrete second time value based on the count value of the second counter and the conversion factor.

[0190] The first operator extracts the start value and the operation value from the second time value and stores them in the start value cache queue and the operation value cache queue respectively; the controller controls the start and stop of the second counter based on the remaining storage space size of the start value cache queue and the operation value cache queue.

[0191] The controller also determines the target number according to the numbering order of the filter groups, and sends the target number, start value and operation value to each filter group; when the number of the filter group is the same as the target number, the filter group is triggered to compare the received start value with the first time value stored earliest in the second FIFO data buffer; if the comparison is consistent, the signal interpolation is obtained based on the signal value stored in the filter group and the received operation value.

[0192] The second operator obtains the Doppler frequency based on the carrier frequency and relative speed output by the configuration module; the direct digital frequency synthesizer obtains the complex signal value based on the Doppler frequency output by the second operator; and the reset term rotation multiplier interpolates the complex signal value output by the direct digital frequency synthesizer and the signal output by the FIFO buffer to form a target signal.

[0193] The various variations and specific examples of the above-mentioned method for simulating broadband signals affected by Doppler frequency in satellite communications are also applicable to the broadband signal simulation system affected by Doppler frequency in satellite communications provided in the present disclosure. Through the above-mentioned detailed description of the method for simulating broadband signals affected by Doppler frequency in satellite communications, those skilled in the art can clearly know the implementation method of the broadband signal simulation system affected by Doppler frequency in satellite communications. For the sake of brevity of the specification, it will not be described in detail here.

[0194] The basic principles of the present disclosure have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this disclosure are merely illustrative and not restrictive, and should not be construed as necessarily possessed by each embodiment of the present disclosure. Furthermore, the specific details disclosed above are provided for illustrative purposes and to facilitate understanding, rather than as limitations. These details do not limit the present disclosure to necessarily being implemented using these specific details.

[0195] In the present disclosure, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. The block diagrams of the devices, devices, equipment, and systems involved in the present disclosure are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0196] Additionally, as used herein, "or" used in a list of items beginning with "at least one" indicates a separate list, so that, for example, a list of "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not mean that the example described is preferred or better than other examples.

[0197] It should also be noted that in the system and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0198] Various changes, substitutions, and modifications may be made to the technology described herein without departing from the teachings defined by the appended claims. Moreover, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of things, means, methods, and actions described above. Currently existing or later developed processes, machines, manufactures, compositions of things, means, methods, or actions that perform substantially the same function or achieve substantially the same results as the corresponding aspects described herein may be utilized. Accordingly, the appended claims include within their scope such processes, machines, manufactures, compositions of things, means, methods, or actions.

[0199] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0200] The above description has been provided for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for simulating a broadband signal affected by Doppler frequency in satellite communications, characterized in that: include: Obtain the original sampling rate of the original broadband signal, the carrier frequency of the satellite, and the relative speed between the satellite and the receiving end; receiving the original broadband signal, sampling the original broadband signal according to the original sampling rate, and obtaining signal values ​​of sampling points in real time; Discretizing the sampling time of the original broadband signal at the original sampling rate and after being affected by the Doppler effect, respectively, to obtain a discrete first time value and a second time value; The step of discretizing the sampling time of the original broadband signal at the original sampling rate and after being affected by the Doppler effect to obtain a discrete first time value and a discrete second time value comprises: When the original broadband signal is received, a first counter and a second counter are started simultaneously, wherein the counting frequency of the second counter is higher than the counting frequency of the first counter; using the count value of the first counter to represent a discrete first time value; Obtaining a conversion factor based on the relative speed and the speed of light; acquiring a discrete second time value based on the count value of the second counter and the conversion factor; storing the real-time acquired signal value and the first time value in parallel into a plurality of filter banks; triggering the filter bank to perform an interpolation operation on the stored signal value based on the second time value and the first time value stored in the filter bank to obtain a signal interpolation value; The step of triggering the filter bank to perform an interpolation operation on the stored signal value based on the second time value and the first time value stored in the filter bank to obtain a signal interpolation value includes: extracting a start value and an operation value from the second time value; Determine a target number according to the numbering order of the filter groups, and send the target number, the start value, and the operation value to each filter group; When the number of the filter group is the same as the target number, triggering the filter group to compare the received start value with the earliest first time value stored in a second FIFO data buffer; wherein the second FIFO data buffer is the data buffer of the filter group; If the comparison is consistent, obtaining a signal interpolation value based on the signal value stored in the filter bank and the received operation value; The step of extracting the start value and the operation value from the second time value includes: extracting an integer part of the second time value as a start value; extracting a decimal part of the second time value as a calculation value; The step of obtaining a signal interpolation value based on the signal value stored in the filter bank and the received operation value comprises: constructing a signal column vector based on the signal values ​​stored by the filter bank; Obtaining a matrix mapping signal vector based on the signal column vector and a preset interpolation matrix; Obtaining a decreasing exponential column vector of the operation value based on the order N of the interpolation matrix; Obtaining a signal interpolation value based on the matrix mapping signal vector and the decreasing index column vector; Sorting the signal interpolation according to the working timing of the plurality of filter groups, and outputting the sorted signal interpolation according to the original sampling rate; frequency modulating the original broadband signal based on the carrier frequency, the relative speed, and the output signal interpolation to form a target signal, wherein the target signal is a broadband signal affected by the Doppler frequency; The step of frequency modulating the original broadband signal based on the carrier frequency, the relative speed, and the output signal interpolation to form a target signal includes: Obtaining a Doppler frequency based on the carrier frequency and the relative speed; obtaining a complex signal value based on the Doppler frequency; Obtaining a signal sample value based on the complex signal value and the output signal interpolation; The signal sample values ​​are outputted in sequence to form a target signal.

2. The method for simulating a broadband signal affected by Doppler frequency in satellite communication according to claim 1, wherein: The step of storing the real-time acquired signal value and the first time value in parallel into a plurality of filter banks comprises: storing the real-time acquired signal values ​​in parallel in the first FIFO data buffers of the plurality of filter banks; The first time value acquired in real time is stored in parallel in the second FIFO data buffers of the plurality of filter banks.

3. The method for simulating a broadband signal affected by Doppler frequency in satellite communication according to claim 1, wherein: Also includes: Storing the startup value and the operation value in a startup value cache queue and an operation value cache queue respectively; The start and stop of the second counter are controlled based on the remaining storage space sizes of the startup value cache queue and the operation value cache queue.

4. A system for simulating a broadband signal affected by Doppler frequency in satellite communications, configured to execute the method for simulating a broadband signal affected by Doppler frequency in satellite communications as claimed in any one of claims 1 to 3, characterized in that: It includes a signal front-end processing module, multiple filter banks, a Doppler calculation module, a sequential value module, a FIFO buffer and a reset item rotation multiplier; The input end of the signal front-end processing module is connected to the output end of the signal source; The output end of the signal front-end processing module is connected to the input end of the Doppler calculation module and the input ends of the multiple filter groups; The input end of the Doppler calculation module is also connected to the output end of the configuration module; The output end of the Doppler calculation module is connected to the input ends of the multiple filter groups and the input end of the reset term rotation multiplier; The output ends of the plurality of filter groups are connected to the input end of the sequential value taking module; The sequential value taking module, the FIFO buffer and the reset item rotation multiplier are connected in sequence.

5. The broadband signal simulation system affected by Doppler frequency in satellite communication according to claim 4, characterized in that: The signal front-end processing module includes a signal receiver and a first counter, and the plurality of filter banks each include a first FIFO data buffer and a second FIFO data buffer; The input end of the signal receiver is connected to the output end of the signal source; The output end of the signal receiver is connected to the input end of the first counter and the input end of the first FIFO data buffer respectively; The output end of the first counter is connected to the input end of the second FIFO data buffer.

6. The broadband signal simulation system affected by Doppler frequency in satellite communication according to claim 5, characterized in that: The Doppler calculation module includes a second counter, a first operator, a start value cache queue, an operation value cache queue, a second operator, a direct digital frequency synthesizer and a controller, and the multiple filter banks also include a comparator and a digital signal processor; The input end of the second counter is connected to the output end of the signal receiver, and the input end of the first operator is connected to the output end of the second counter and the output end of the configuration module; The output end of the first operator is connected to the input end of the startup value cache queue and the input end of the calculation value cache queue, and the input end of the controller is connected to the output end of the startup value cache queue and the output end of the calculation value cache queue; The input end of the comparator is connected to the output end of the controller and the output end of the second FIFO data buffer, and the controller is also connected to the second counter and the digital signal processor; The input end of the digital signal processor is connected to the output end of the comparator and the output end of the first FIFO data buffer, and the output end of the digital signal processor is connected to the input end of the sequential value module; The input end of the second operator is connected to the output end of the configuration module, and the output end of the second operator is connected to the input end of the direct digital frequency synthesizer; An output terminal of the direct digital frequency synthesizer is connected to an input terminal of the reset term rotation multiplier.

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