Method, apparatus, device and medium for signal capture

Abstract

The present application discloses a method, apparatus, device and medium for signal capture, which are used to reduce the resource overhead and time delay of capturing signals. The method includes: receiving a signal; determining the frequency offset of the signal by using the energy centroid method; performing frequency offset compensation on the signal based on the frequency offset of the signal; and capturing the signal based on the frequency deviation range after the frequency offset compensation is performed on the signal. The present application performs frequency offset compensation on the signal. After the compensation, the maximum fixed frequency deviation range of the signal will become smaller, and then the length of the frequency domain search window determined based on the smaller frequency deviation range will also become smaller; in this way, the resource overhead and time delay can be reduced when capturing the signal.

Description

Technical Field

[0001] This application relates to the field of satellite communication technology, and in particular, to a method, apparatus, device, and medium for signal acquisition. Background Art

[0002] The prerequisite for processing a signal is to capture the signal. Typical signal capture methods include: coherent search method based on frequency-domain parallelism, differential correlation method. For satellite communication, due to high performance requirements and complex transmission environments, the coherent search method based on frequency-domain parallelism is generally used to capture signals.

[0003] For the coherent search method based on frequency-domain parallelism, it includes the following processes: determining the time-domain search window length according to the maximum timing deviation range; determining the frequency-domain search window length according to the maximum fixed frequency deviation range (the maximum fixed frequency deviation range is given according to specific protocol requirements, generally a fixed value, such as 2 kHz), the maximum Doppler frequency change rate range, and the maximum signal duration; determining the time-frequency search window based on the time-domain search window length and the frequency-domain search window length; searching for the synchronization header of the signal within the time-frequency search window to complete signal capture. The coherent search method based on frequency-domain parallelism has excellent performance, but has high resource overhead and large latency. Summary of the Invention

[0004] This application provides a method, apparatus, device, and medium for signal acquisition, which are used to reduce resource overhead and latency when capturing signals.

[0005] In a first aspect, this application provides a method for signal acquisition, including:

[0006] Receiving a signal;

[0007] Using the energy centroid method to determine the frequency offset of the signal;

[0008] Based on the frequency offset of the signal, performing frequency offset compensation on the signal;

[0009] Based on the frequency deviation range after performing frequency offset compensation on the signal, capturing the signal.

[0010] In a possible implementation, the using the energy centroid method to determine the frequency offset of the signal includes: based on the fast Fourier transform (FFT), determining the amplitude of the signal at each frequency point; based on the amplitude of the signal at each frequency point, determining the energy of the signal; determining the centroid of the energy of the signal; based on the centroid, determining the frequency offset of the signal.

[0011] In a possible implementation, based on the fast Fourier transform (FFT), determining the amplitude of the signal at each frequency point includes: determining the amplitude of the signal at each frequency point based on the following formula; Sigamp = fftshift(abs(fft(Sig in , N FFT ))), where sig amp is the amplitude of the signal at each frequency point, Sig in is the signal, N FFT is the number of FFT points, fft() is the FFT operation, (fftshift() is the spectrum shifting operation, and abs() represents taking the modulus value.

[0012] In a possible implementation, based on the amplitude of the signal at each frequency point, determining the energy of the signal includes: determining the energy of the signal based on the following formula; Sig pow = Sig amp 2 ; Sig total_pow = sum(Sig pow ); where sig amp is the amplitude of the signal at each frequency point, Sig pow is the energy of the signal at each frequency point, Sig total_pow is the energy of the signal.

[0013] In a possible implementation, determining the centroid of the energy of the signal includes: determining the centroid of the energy of the signal based on the following formula; Weight = sum(i * sig pow ) / sig total_pow ; where i = 0, 1,..., N FFT , N FFT is the number of FFT points.

[0014] In a possible implementation, based on the centroid, determining the frequency offset of the signal includes: determining the frequency offset of the signal based on the following formula; f offset = (Weight - N FFT / 2) * F s / N FFT ; where f offset is the frequency offset of the signal, Weight is the centroid, F s is the sampling rate of the signal, N FFT is the number of FFT points.

[0015] In a second aspect, the present application provides a signal acquisition device, the device includes:

[0016] A receiving module, configured to receive a signal;

[0017] A determining module, configured to determine the frequency offset of the signal by using the energy centroid method;

[0018] A compensation module for compensating the frequency offset of the signal based on the frequency offset of the signal;

[0019] A capture module for capturing the signal based on the frequency deviation range after compensating the frequency offset of the signal.

[0020] In a possible implementation, the determining module is specifically configured to determine the amplitude of the signal at each frequency point based on the Fast Fourier Transform (FFT); determine the energy of the signal based on the amplitude of the signal at each frequency point; determine the centroid of the energy of the signal; and determine the frequency offset of the signal based on the centroid.

[0021] In a possible implementation, the determining module is specifically configured to determine the amplitude of the signal at each frequency point based on the following formula: Sig amp =fftshift(abs(fft(Sig in ,N FFT ))), where sig amp is the amplitude of the signal at each frequency point, Sig in is the signal, N FFT is the number of FFT points, fft(·) is the FFT operation, (fftshift(·) is the spectrum shifting operation, and abs(·) represents taking the modulus value.

[0022] In a possible implementation, the determining module is specifically configured to determine the energy of the signal based on the following formula: Sig pow =Sig amp 2 ; Sig total_pow =sum(Sig pow ); where sig amp is the amplitude of the signal at each frequency point, Sig pow is the energy of the signal at each frequency point, and Sig total_pow is the energy of the signal.

[0023] In a possible implementation, the determining module is specifically configured to determine the centroid of the energy of the signal based on the following formula: Weight = sum(i.*Sig pow ) / Sig total_pow ; where i = 0, 1,..., N FFT , and N FFT is the number of FFT points.

[0024] In a possible implementation, the determining module is specifically configured to determine the frequency offset of the signal based on the following formula: f offset =(Weight - N FFT / 2)*F s / N FFT ; where f offset is the frequency offset of the signal, Weight is the center of gravity, F s is the sampling rate of the signal, N FFT is the number of FFT points.

[0025] In a third aspect, the present application provides a communication device, including: a processor, and optionally, a memory; the processor is coupled to the memory; the memory is configured to store computer programs or instructions; the processor is configured to execute some or all of the computer programs or instructions in the memory, and when the some or all of the computer programs or instructions are executed, it is configured to implement the functions in any one of the above methods.

[0026] In a possible implementation, the device may further include a transceiver, and the transceiver is configured to send the signal processed by the processor or receive the signal input to the processor. The transceiver may perform the sending action or the receiving action of any one of the methods.

[0027] In a fourth aspect, a computer-readable storage medium is provided, which is configured to store a computer program, and the computer program includes instructions for implementing the functions in any one of the above.

[0028] Alternatively, a computer-readable storage medium is provided, which is configured to store a computer program, and when the computer program is executed by a computer, it can cause the computer to execute any one of the above methods.

[0029] In a fifth aspect, a computer program product is provided, and the computer program product includes: computer program code, and when the computer program code runs on a computer, it causes the computer to execute any one of the above methods.

[0030] The present application performs frequency offset compensation on the signal. After the compensation, the maximum fixed frequency deviation range of the signal becomes smaller, and then the length of the frequency domain search window determined based on the smaller frequency deviation range also becomes smaller; in this way, the resource overhead and latency can be reduced when capturing the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the implementation manners in the related art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the related art. Obviously, the following drawings are some embodiments of the present application, and for those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0032] Figure 1 shows a schematic flow diagram of signal capture provided by an embodiment of the present application;

[0033] Figure 2 Shows a structural diagram of a signal acquisition device provided by an embodiment of the present application;

[0034] Figure 3 Shows a structural diagram of a communication device provided by an embodiment of the present application. Detailed implementation manners

[0035] To make the objectives and implementation manners of the present application clearer, the following will clearly and completely describe the exemplary implementation manners of the present application with reference to the accompanying drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only a part, rather than all, of the embodiments of the present application. Terms such as "first", "second", "third", etc. in the specification, claims and the above drawings of the present application are used to distinguish similar or like objects or entities, and do not necessarily mean to limit a specific order or sequence, unless otherwise specified. It should be understood that such terms can be interchanged under appropriate circumstances.

[0036] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

[0037] Due to reasons such as the deviation of the local oscillator frequencies at the transmitting and receiving ends, Doppler frequency shift, etc., when the signal reaches the receiving end, the frequency is already different from when it was first transmitted. For example, if the carrier frequency of the transmitted signal is 2000 Hz and the Doppler frequency offset is assumed to be 30 Hz, and the local oscillator of the receiver generates a carrier frequency of 1998 Hz at this time, there is a frequency offset of 2000 + 30 - 1998 = 32 Hz.

[0038] Figure 1 Shows a schematic flow diagram of a signal acquisition provided by an embodiment of the present application, and this process includes the following steps:

[0039] Step 101: Receive a signal.

[0040] This signal can be a signal sent by a satellite.

[0041] This signal acquisition method can be applied to the receiving end, which can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; it can also be deployed on the water surface (such as ships, etc.); it can also be deployed in the air (such as on airplanes, balloons, etc.). The receiving end can be a mobile phone, a tablet, a computer with wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, etc.

[0042] Step 102: Use the energy centroid method to determine the frequency offset of the signal.

[0043] Step 103: Based on the frequency offset of the signal, perform frequency offset compensation on the signal.

[0044] For example, determine the phase compensation factor corresponding to the frequency offset of each sampling point of the signal, and multiply each point of the obtained signal by the conjugate of the phase compensation factor, that is, complete the frequency offset compensation of the signal. Frequency offset compensation is to compensate the frequency offset of the signal passing through the channel. For example, if the signal was originally offset by 50 Hz, and the energy centroid method is used to determine that the frequency offset of the signal is 48 Hz, after compensating back 48 Hz, the frequency offset of the signal is 2 Hz.

[0045] Step 104: Based on the frequency deviation range after performing frequency offset compensation on the signal, acquire the signal.

[0046] Acquiring the signal can be understood as determining the position of the signal.

[0047] The process of Step 104 can adopt a conventional acquisition algorithm.

[0048] In the current satellite communication system, conventional acquisition algorithms are used for frequency offset estimation. The current acquisition algorithms are mainly based on the received signal, which is the product of the local generated pseudo-code sequence and the local carrier. The received signal is multiplied by the local generated pseudo-code sequence to form an in-phase signal, and then is orthogonal to the local carrier to form an orthogonal signal. When the two signals cross each other, acquisition can be completed.

[0049] The present application compensates for the frequency offset of the signal. After the compensation, the range of the frequency deviation of the signal becomes smaller, and then the length of the frequency-domain search window determined based on the reduced frequency deviation range also becomes smaller. In this way, the resource overhead and latency can be reduced when capturing the signal.

[0050] Before the conventional capture algorithm, a one-step coarse frequency offset estimation based on the energy centroid method is added to reduce the search range and improve the search time and accuracy.

[0051] The following introduces a possible implementation of determining the frequency offset of the signal using the energy centroid method:

[0052] First, based on the fast Fourier transform (FFT), determine the amplitude of the signal at each frequency point;

[0053] Then, based on the amplitudes of the signal at each frequency point, determine the energy of the signal; where each frequency point is the frequency point at which the signal is received;

[0054] Next, determine the centroid of the energy of the signal;

[0055] Finally, based on the centroid, determine the frequency offset of the signal.

[0056] The following details each process:

[0057] When determining the amplitude of the signal at each frequency point based on the fast Fourier transform (FFT), specifically, it can be: based on the following formula, determine the amplitude of the signal at each frequency point;

[0058] Sig amp =fftshift(abs(fft(Sig in ,N FFT )));

[0059] where sig amp is the amplitude of the signal at each frequency point, Sig in is the signal, N FFT is the number of FFT points, fft(·) is the FFT operation, (fftshift(·) is the spectrum shifting operation, only used for spectrum observation and does not affect the signal amplitude, and abs(·) represents taking the modulus value.

[0060] The amplitude at each frequency point is the spectral amplitude. The spectrum is short for the frequency spectrum density and is the distribution curve of frequency. A complex oscillation is decomposed into harmonic oscillations with different amplitudes and frequencies, and the graph of the amplitudes of these harmonic oscillations arranged by frequency is called the spectrum. The abscissa of the spectrum is a certain frequency, and the ordinate represents the spectral value corresponding to this frequency, that is, the magnitude of the amplitude, indicating the strength of the signal corresponding to the spectral value of this frequency.

[0061] When determining the energy of the signal based on the amplitude of the signal at each frequency point, specifically, it can be: determining the energy of the signal based on the following formula;

[0062] Sig pow = Sig amp 2 ; Sig total_pow = sum(Sig pow );

[0063] where sig amp is the amplitude of the signal at each frequency point, Sig pow is the energy of the signal at each frequency point, and Sig total_pow is the energy of the signal.

[0064] When determining the centroid of the energy of the signal, specifically, it can be: determining the centroid of the energy of the signal based on the following formula;

[0065] Weight = sum(i.*Sig pow ) / Sig total_pow ;

[0066] where i = 0, 1,..., N FFT , and N FFT is the number of FFT points.

[0067] When determining the frequency offset of the signal based on the centroid, specifically, it can be:

[0068] Determining the frequency offset of the signal based on the following formula;

[0069] f offset = (Weight - N FFT / 2) * F s / N FFT ;

[0070] where f offset is the frequency offset of the signal, Weight is the centroid, F s is the sampling rate of the signal, and N FFT is the number of FFT points. Among them, the frequency offset of the signal is the offset value of the centroid, and the centroid offset value is the value of the change in the centroid before and after the signal passes through the channel.

[0071] The maximum fixed frequency deviation range will be given according to specific protocol requirements. Generally, it is a fixed value, assumed to be C (it may be a large number like 2 kHz, which depends on the situation. The size of C determines the anti-interference ability of the frequency offset estimation algorithm). Through the energy centroid method for frequency offset estimation, and after frequency offset compensation of the signal, this maximum fixed frequency deviation range will be reduced. For example, it is reduced to about [-10 Hz, 10 Hz]. In this way, the maximum fixed frequency deviation range becomes smaller, and the search range of the frequency domain parallel algorithm will become smaller, thus reducing the total resource consumption.

[0072] In addition, through simulation, the accuracy of frequency offset estimation will also increase. After simulation, the accuracy of frequency offset estimation can be improved by about 20% under the condition of the same signal-to-noise ratio.

[0073] Based on the same technical concept, as Figure 2 shown, the present application also provides a signal acquisition device, and the device includes:

[0074] A receiving module 21, configured to receive a signal;

[0075] A determining module 22, configured to determine the frequency offset of the signal by using the energy centroid method;

[0076] A compensation module 23, configured to perform frequency offset compensation on the signal based on the frequency offset of the signal;

[0077] A capturing module 24, configured to capture the signal based on the frequency deviation range after frequency offset compensation of the signal.

[0078] In a possible implementation, the determining module 22 is specifically configured to determine the amplitude of the signal at each frequency point based on the fast Fourier transform FFT; determine the energy of the signal based on the amplitude of the signal at each frequency point; determine the centroid of the energy of the signal; and determine the frequency offset of the signal based on the centroid.

[0079] In a possible implementation, the determining module 22 is specifically configured to determine the amplitude of the signal at each frequency point based on the following formula; Sig amp =fftshift(abs(fft(Sig in ,N FFT ))), where sig amp is the amplitude of the signal at each frequency point, Sig in is the signal, N FFT is the number of FFT points, fft() is the FFT operation, (fftshift() is the spectrum shifting operation, and abs() represents taking the modulus value.

[0080] In a possible implementation, the determining module 22 is specifically configured to determine the energy of the signal based on the following formula: Sig pow = Sig amp 2 ; Sig total_pow = sum(Sig pow ); where sig amp is the amplitude of the signal at each frequency point, Sig pow is the energy of the signal at each frequency point, and Sig total_pow is the energy of the signal.

[0081] In a possible implementation, the determining module 22 is specifically configured to determine the center of gravity of the energy of the signal based on the following formula: Weight = sum(i.*Sig pow ) / Sig total_pow ; where i = 0, 1,..., N FFT , and N FFT is the number of FFT points.

[0082] In a possible implementation, the determining module 22 is specifically configured to determine the frequency offset of the signal based on the following formula: f offset = (Weight - N FFT / 2) * F s / N FFT ; where f offset is the frequency offset of the signal, Weight is the center of gravity, F s is the sampling rate of the signal, and N FFT is the number of FFT points.

[0083] Based on the same technical concept, the present application also provides a communication device, Figure 3 which shows a schematic structural diagram of a communication device, as Figure 3 shown, including: a processor 31. Optionally, it further includes: a communication interface 32, a memory 33, and a communication bus 34. Among them, the processor 31, the communication interface 32, and the memory 33 communicate with each other through the communication bus 34;

[0084] A computer program is stored in the memory 33. When the program is executed by the processor 31, the processor 31 is caused to complete the steps of the above signal capture method.

[0085] The communication bus mentioned in the above communication device may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of convenience of representation, only a thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0086] The communication interface 32 is used for communication between the above communication device and other devices.

[0087] The memory may include a Random Access Memory (RAM), or may also include a Non-Volatile Memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located far from the aforementioned processor.

[0088] The above processor may be a general-purpose processor, including a central processing unit, a Network Processor (NP), etc.; it may also be a Digital Signal Processing (DSP), an application-specific integrated circuit, a field-programmable gate array, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0089] Based on the same technical concept, on the basis of the above embodiments, the present application provides a computer-readable storage medium, in which a computer program executable by a communication device is stored, and the computer-executable instructions are used to cause a computer to execute the steps of the above signal capture method.

[0090] The above computer-readable storage medium may be any available medium or data storage device accessible by the processor in the communication device, including but not limited to magnetic memories such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc., optical memories such as CDs, DVDs, BDs, HVDs, etc., and semiconductor memories such as ROM, EPROM, EEPROM, non-volatile memories (NAND FLASH), solid-state drives (SSD), etc.

[0091] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0092] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices produce means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0093] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0094] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0095] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A method for signal acquisition, characterized in that, Comprising: Receiving a signal; Using the energy centroid method to determine the frequency offset of the signal; Based on the frequency offset of the signal, performing frequency offset compensation on the signal; Based on the frequency deviation range after performing frequency offset compensation on the signal, capturing the signal; The using the energy centroid method to determine the frequency offset of the signal includes: Based on the fast Fourier transform (FFT), determining the amplitude of the signal at each frequency point; Based on the amplitude of the signal at each frequency point, determining the energy of the signal; Determining the centroid of the energy of the signal; Based on the centroid, determining the frequency offset of the signal.

2. The method according to claim 1, wherein Based on the fast Fourier transform (FFT), determining the amplitude of the signal at each frequency point includes: Based on the following formula, determining the amplitude of the signal at each frequency point; Sig amp = fftshift(abs(fft(Sig in , N FFT ))), where Sig amp is the amplitude of the signal at each frequency point, Sig in is the signal, N FFT is the number of FFT points, fft(·) is the FFT operation, fftshift(·) is the spectrum shifting operation, and abs(·) represents taking the modulus value.

3. The method according to claim 1, wherein Based on the amplitude of the signal at each frequency point, determining the energy of the signal includes: Based on the following formula, determining the energy of the signal; Sig pow = Sig amp 2 ; Sig total_pow = sum(Sig pow ); Among them, Sig amp is the amplitude of the signal at each frequency point, Sig pow is the energy of the signal at each frequency point, Sig total_pow is the energy of the signal.

4. The method according to claim 1, characterized in that The determining the centroid of the energy of the signal includes: Based on the following formula, determining the centroid of the energy of the signal; Weight=sum(i.*Sig pow ) / Sig total_pow ; where \(i = 0, 1, \ldots, N\) FFT , \(N\) FFT is the number of FFT points.

5. The method according to claim 1, wherein The based on the centroid, determining the frequency offset of the signal includes: Based on the following formula, determining the frequency offset of the signal; f offset = (Weight - N FFT / 2) * F s / N FFT ; where f offset is the frequency offset of the signal, Weight is the center of gravity, F s is the sampling rate of the signal, N FFT is the number of FFT points.

6. A signal acquisition device, characterized in that, The device includes: An acquisition module, configured to receive a signal; A determination module, configured to use the energy centroid method to determine the frequency offset of the signal; A compensation module, configured to perform frequency offset compensation on the signal based on the frequency offset of the signal; A capture module, configured to capture the signal based on the frequency deviation range after performing frequency offset compensation on the signal; The determination module is specifically configured to: based on the fast Fourier transform (FFT), determine the amplitude of the signal at each frequency point; based on the amplitude of the signal at each frequency point, determine the energy of the signal; determine the centroid of the energy of the signal; based on the centroid, determine the frequency offset of the signal.

7. A communication device, characterized in that, Comprising: A processor and a memory; The memory is configured to store computer programs or instructions; The processor is configured to execute some or all of the computer programs or instructions in the memory, and when the some or all of the computer programs or instructions are executed, is configured to implement the method according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, For storing a computer program, the computer program includes instructions for implementing the method according to any one of claims 1-5.

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