Residual frequency offset compensation method, device, equipment, storage medium and computer program product

Abstract

The present application relates to the field of satellite communication technology, and discloses a residual frequency offset compensation method, device, equipment, storage medium and computer program product, including: determining the linear interpolation phase step according to the frame header information in the data frame; calculating the phase offset estimation value and the phase change parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame; when it is detected that the phase offset estimation value has a phase cross cycle, the phase offset estimation value is compensated according to the phase change parameter to obtain the modulated data phase information. A large residual frequency offset estimation and residual phase linear interpolation compensation can be performed once in each frame, which reduces the complexity of carrier precision synchronization and phase recovery, and greatly shortens the system phase recovery time under low symbol rate conditions.

Description

Technical Field

[0001] The present application relates to the field of satellite communication technology, and in particular to a residual frequency offset compensation method, device, equipment, storage medium and computer program product. Background Art

[0002] At present, in low-orbit satellite communication systems, under the conditions of low symbol rate and low signal-to-noise ratio, if fewer pilot blocks are used to make the carrier precise synchronization converge quickly, the larger residual frequency offset will cause the phase difference between adjacent pilot blocks to cross-cycle, making it impossible for the receiver to correctly estimate the residual frequency offset and phase offset, resulting in a decrease in the receiver demodulation performance. Summary of the invention

[0003] The main purpose of the present application is to provide a residual frequency offset compensation method, device, equipment, storage medium and computer program product, aiming to solve the technical problem that in the current low-orbit satellite communication system, under the conditions of low symbol rate and low signal-to-noise ratio, if fewer pilot blocks are used to make the carrier precise synchronization converge quickly, the larger residual frequency offset will cause the phase difference between adjacent pilot blocks to cross-cycle, making it impossible for the receiver to correctly estimate the residual frequency offset and phase offset, resulting in a decrease in the receiver demodulation performance.

[0004] To achieve the above object, the present application proposes a residual frequency offset compensation method, the residual frequency offset compensation method comprising:

[0005] Determine the linear interpolation phase step according to the frame header information in the data frame;

[0006] Calculate a phase offset estimation value and a phase change parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame;

[0007] When it is detected that the phase shift estimation value has a phase cross-cycle, the phase shift estimation value is compensated according to the phase change parameter to obtain the modulation data phase information.

[0008] Optionally, when it is detected that the phase shift estimation value has a phase cross-cycle, the step of compensating the phase shift estimation value according to the phase change parameter to obtain the phase information of the modulated data includes:

[0009] Calculate a first phase interpolation of the medians of two preceding and succeeding pilot signals based on the phase offset estimation value;

[0010] When it is detected that the phase offset estimation value has a phase cross cycle, performing corresponding cycle skip compensation on the first phase interpolation according to the phase change parameter to obtain a second phase interpolation;

[0011] The second phase interpolation value is divided by the interval data to obtain a linear phase interpolation step value, and considering the initial phase, the data segments in the data frame are segmentedly compensated based on the linear phase interpolation step value and the phase offset estimation value to obtain modulated data phase information.

[0012] Optionally, the frame header information includes SOF information and PLSC information;

[0013] The step of determining the linear interpolation phase step according to the frame header information in the data frame comprises:

[0014] Conjugate-multiply the SOF information and the PLSC information in the frame header information with the locally stored SOF signal and the PLSC signal respectively to obtain first phase information and second phase information;

[0015] Accumulate and sum the first phase information and the second phase information based on the number of frame header symbols in the data frame to obtain a first phase value and a second phase value;

[0016] The phase difference of the frame header information is calculated according to the first phase value and the second phase value, and a linear interpolation phase step is determined based on the phase difference and the interval data.

[0017] Optionally, before the step of conjugate-multiplying the SOF information and the PLSC information in the frame header information with the locally stored SOF signal and the PLSC signal respectively to obtain the first phase information and the second phase information, the step further includes:

[0018] Acquiring received signals when there is residual frequency offset;

[0019] The received signal is subjected to frame synchronization and frame header decoding to obtain a data frame, and the data frame is subjected to frame de-framing processing to obtain SOF information and PLSC information.

[0020] Optionally, after the step of calculating the phase difference of the frame header information according to the first phase value and the second phase value, and determining the linear interpolation phase step based on the phase difference and the interval data, the method further includes:

[0021] When there is a phase jump in the phase difference, adjusting the phase difference according to a preset adjustment period to obtain a target phase;

[0022] A calculation is performed based on the target phase, the interval data and the system sampling rate to obtain a maximum processable frequency deviation range.

[0023] Optionally, the step of calculating the phase offset estimate and the phase change parameter between any two pilot signals in the data frame based on the linear interpolation phase step comprises:

[0024] Determine a phase offset estimate between pilots based on the linear interpolation phase step and the spacing data;

[0025] The ratio of the phase offset estimate to the interval data is rounded down to obtain a phase change parameter.

[0026] In addition, to achieve the above-mentioned purpose, the present application also proposes a residual frequency offset compensation device, the residual frequency offset compensation device comprising:

[0027] A step length calculation module, used for determining a linear interpolation phase step length according to frame header information in a data frame;

[0028] An offset estimation module, used for calculating a phase offset estimation value and a phase change parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame;

[0029] The frequency offset compensation module is used to compensate the phase offset estimation value according to the phase change parameter to obtain the modulated data phase when it is detected that the phase offset estimation value crosses the phase cycle.

[0030] In addition, to achieve the above-mentioned purpose, the present application also proposes a residual frequency offset compensation device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the residual frequency offset compensation method described above.

[0031] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the residual frequency offset compensation method described above are implemented.

[0032] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, wherein the computer program product includes a computer program, and when the computer program is executed by a processor, the steps of the residual frequency offset compensation method as described above are implemented.

[0033] The present application discloses determining the linear interpolation phase step according to the frame header information in the data frame; calculating the phase offset estimation value and the phase change parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame; when the phase offset estimation value is detected to have a phase cross cycle, the phase offset estimation value is compensated according to the phase change parameter to obtain the modulated data phase information. A large residual frequency offset estimation and residual phase linear interpolation compensation can be performed once in each frame, reducing the complexity of carrier precision synchronization and phase recovery, and greatly shortening the system phase recovery time under low symbol rate conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0036] Figure 1 This is a flow chart of a first embodiment of a residual frequency offset compensation method of the present application;

[0037] Figure 2 This is a diagram of the implementation steps of the residual frequency offset compensation method of this application;

[0038] Figure 3 This is a flow chart of a second embodiment of the residual frequency offset compensation method of the present application;

[0039] Figure 4 This is the DVB-S2 frame structure diagram used in this application;

[0040] Figure 5 A schematic diagram of a flow chart of a third embodiment of a residual frequency offset compensation method of the present application;

[0041] Figure 6 This is a block diagram of the implementation of the residual frequency offset compensation algorithm of this application;

[0042] Figure 7 This is a schematic diagram of the module structure of the residual frequency offset compensation device according to an embodiment of the present application;

[0043] Figure 8 Schematic diagram of the device structure of the hardware operating environment involved in the residual frequency offset compensation method in the embodiment of the present application.

[0044] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0045] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0046] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0047] The main solution of the embodiment of the present application is: determine the linear interpolation phase step according to the frame header information in the data frame; calculate the phase offset estimate and the phase change parameter based on the linear interpolation phase step and the interval data between any two pilot signals in the data frame; when it is detected that the phase offset estimate has a phase cross-cycle, compensate the phase offset estimate according to the phase change parameter to obtain the modulated data phase information.

[0048] Due to the rapid development of low-orbit satellite communications in recent years, with the diversification of satellite-to-ground communication mission requirements, the amount of data transmitted by the satellite-to-ground link has increased significantly. In low-orbit satellite communication systems, due to the differences in transceiver equipment and the rapid movement of satellites, the system will introduce variable frequency offsets and phase offsets. In communication systems with auxiliary data, the receiver usually first performs coarse carrier synchronization and fine carrier synchronization to compensate for the frequency offset, and then uses the auxiliary data to estimate the phase offset to compensate for the phase offset. However, under low symbol rate and low signal-to-noise ratio conditions, it takes a long time to calculate to converge to a residual frequency offset that meets the requirements. If fewer pilot blocks are used to make the carrier fine synchronization converge quickly, a larger residual frequency offset will cause the phase difference between adjacent pilot blocks to cross the period. At this time, the phase linear interpolation method cannot be used, otherwise it will cause the constellation diagram to form a loop, resulting in the problem of being unable to demodulate normally.

[0049] Therefore, the present application provides a residual frequency offset estimation and compensation method based on the DVB-S2 (Digital Video Broadcasting-Satellite Second Generation, second-generation digital video broadcasting standard) frame structure, which can solve the phase offset problem caused by large residual frequency offset under low symbol rate and changing Doppler conditions, and improve the demodulation performance of the system.

[0050] It should be noted that the execution subject of this embodiment may be a computing service device with data processing, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or an electronic device capable of realizing the above functions, etc. The following takes a satellite communication system as an example to illustrate this embodiment and the following embodiments.

[0051] Based on this, the embodiment of the present application provides a residual frequency offset compensation method, referring to Figure 1 , Figure 1 Schematic diagram of the flow chart of the first embodiment of the residual frequency offset compensation method of the present application.

[0052] In this embodiment, the residual frequency offset compensation method includes:

[0053] Step S10: determining a linear interpolation phase step according to frame header information in the data frame.

[0054] It should be understood that the data frame is a protocol data unit of the data link layer. Each data frame contains a frame header and a data part. The frame header contains important control information for synchronization, address recognition and parameter setting. The frame header based on the DVB-S2 frame structure contains SOF (Start Of Frame) segment data and PLSC (Physical Layer Signalling Code) data. The linear interpolation phase step is the phase change between two adjacent known phase points in the linear interpolation method, which is used to calculate the phase value of the unknown phase point.

[0055] It can be understood that at the receiving end, the frame header information of the data frame is first identified and extracted through frame synchronization technology. Then, the specific sequence in the frame header (such as the synchronization sequence SOF and the physical layer signaling code PLSC) is used to conjugate multiply with the corresponding sequence stored locally to remove the phase information of the modulated signal. Then, by calculating the phase value of the signal after conjugate multiplication, the phase information of each point in the frame header can be obtained. Based on the phase information of the known points in the frame header, the system can calculate the phase difference between adjacent points, and then deduce the linear interpolation phase step. This step is used to interpolate and compensate the phase of the unknown point in subsequent data processing to restore the phase information of the original signal.

[0056] Step S20, calculating a phase offset estimation value and a phase change parameter based on the linear interpolation phase step and the interval data between any two pilot signals in the data frame.

[0057] It should be noted that the pilot is a known data inserted into the data symbol for synchronization, channel estimation or phase recovery in the communication system. In satellite communications, the pilot is often used to help the receiving end estimate and compensate for frequency offset and phase offset. The phase offset estimate refers to the difference between the signal phase obtained by calculation and the ideal phase. In satellite communications, the phase offset estimate is used to guide the receiving end to perform phase compensation to restore the phase information of the original signal. The phase change parameter refers to the parameter that describes the change of the signal phase over time or frequency in satellite communications, including frequency offset, phase offset, etc. The interval data is the number of data points or time interval between two adjacent pilot symbols in the data frame. Through the known pilot signal and the interval data between them, the channel characteristics can be estimated more accurately, thereby optimizing the data demodulation and decoding process. At the receiving end, the interval data between the pilots can be used to calculate the phase change, so as to perform phase compensation and reduce the phase error.

[0058] It should be understood that after obtaining the linear interpolation phase step, the phase value of the unknown phase point can be calculated based on the interval data between any two pilots in the data frame. Then, these calculated phase values ​​are compared with the ideal phase value to obtain the phase offset estimate. The phase change parameter can be extracted by further analyzing and processing the phase offset estimate. For example, the overall change trend of the phase can be evaluated by calculating the average value, variance and other statistics of the phase offset estimate. The relationship between the phase offset estimate and time or frequency can also be used to extract phase change parameters such as frequency deviation and phase deviation. After obtaining the phase offset estimate and phase change parameters, the receiving end can use this information for phase compensation. By adjusting the phase of the received signal, the influence of phase offset and phase change on signal quality can be eliminated or reduced. Finally, the phase information of the original signal is restored to ensure accurate demodulation of the data.

[0059] Step S30: When it is detected that the phase shift estimation value has a phase cross-cycle, the phase shift estimation value is compensated according to the phase change parameter to obtain the modulation data phase information.

[0060] It should be noted that phase cross-cycle means that during the phase estimation process, due to large frequency deviation or long observation time, the phase change exceeds 2π (one cycle), causing the phase estimation value to "jump" from the positive or negative direction to another cycle. Phase cross-cycle leads to inaccurate phase estimation, affecting the demodulation quality of the signal. The modulated data phase information is the phase information carried in the signal after modulation compensation. The receiving end needs to accurately restore this phase information to correctly demodulate the data.

[0061] For ease of understanding, the following examples are provided, but are not intended to limit the present application. Figure 2 , Figure 2 This is a diagram of the implementation steps of the residual frequency offset compensation method of the present application. First, execute step 1 to conjugate and multiply the SOF information segment in the synchronized frame header with the locally stored SOF data, obtain the phase of the conjugated data, and simultaneously obtain the phase of the PLSC and pilot block. Then execute step 2 to calculate the phase difference between the frame header SOF and PLSC, and process the phase jump; calculate the linear interpolation phase step of SOF and PLSC. Then implement step 3 to calculate the phase change of the frame header and the pilot block, as well as the data symbol phase between two adjacent pilot blocks, obtain the phase difference jump N_pi, and perform modulus processing. In step 4, the true phase difference between the front and rear pilot blocks is calculated by N_pi, and the data symbol phase step value between the pilot blocks is calculated by linear interpolation. Finally, through step 5, the initial phase and the phase accumulation value are calculated in segments in units of frames, and the segmented data is linearly interpolated to compensate the phase.

[0062] In this embodiment, the linear interpolation phase step is determined according to the frame header information in the data frame; the phase offset estimation value and the phase change parameter are calculated based on the linear interpolation phase step and the interval data between any two pilots in the data frame; when the phase offset estimation value is detected to have a phase cross cycle, the phase offset estimation value is compensated according to the phase change parameter to obtain the modulated data phase information. A large residual frequency offset estimation and residual phase linear interpolation compensation can be performed once in each frame, which reduces the complexity of carrier precision synchronization and phase recovery, and greatly shortens the system phase recovery time under low symbol rate conditions.

[0063] Reference Figure 3 , Figure 3 This is a flow chart of a second embodiment of a residual frequency offset compensation method of the present application. Based on the above first embodiment, a second embodiment of a residual frequency offset compensation method of the present application is proposed.

[0064] In this embodiment, the step S10 includes:

[0065] Step S101 : Conjugate-multiply the SOF information and the PLSC information in the frame header information with the locally stored SOF signal and PLSC signal respectively to obtain first phase information and second phase information.

[0066] It should be understood that the first phase information and the second phase information are SOF information and PLSC information respectively, which remove the phase information of the modulated signal, and can be used for subsequent phase compensation, frequency offset estimation and other processing, thereby helping the receiving end to correctly modulate and decode data. Conjugate multiplication refers to multiplying the conjugate of two complex signals (that is, the real part remains unchanged and the imaginary part is negated) with another complex signal. In communication systems, conjugate multiplication is often used to remove the phase information of the modulated signal to obtain the amplitude information or phase difference information of the signal.

[0067] It is understandable that, at the receiving end, in order to perform frame synchronization and decoding of physical layer signaling, the same SOF signal and PLSC signal as the transmitting end are usually pre-stored, and these locally stored signals are used to match and compare with the received signals.

[0068] For ease of understanding, the following examples are provided, but are not intended to limit the present application. Figure 4 , Figure 4This is a diagram of the DVB-S2 frame structure used in this application. The figure is divided into two main areas: the valid data area and the PL frame header and pilot block area. In the valid data area, the data is organized into multiple time slots (Slots), from Slot-1 to Slot-S. These time slots are the basic units of data transmission, and each time slot can contain a certain number of symbols for transmitting user data. In the PL frame header and pilot block area, the data structure includes a PL frame header and multiple pilot blocks. The PL frame header contains two important parts: SOF and PLSC. SOF is a sequence of 26 symbols used to indicate the start of the frame. π / 2 - BPSK is a binary phase-shift keying (BPSK) modulation method, and π / 2 means that the phase is offset by 90 degrees. PLSC is a sequence of 64 symbols used to assist the receiving end in phase and frequency synchronization. The pilot block area consists of 16 time slots, each of which contains a certain number of symbols. The pilot block is used to provide the reference signal required by the receiving end for channel estimation and phase correction. It contains 36 symbols and the pilot structure can be pre-set. In the figure, the modulation mode of the 16 time slots can be changed, which means that the modulation mode of the pilot block can be adjusted as needed.

[0069] After the received signal is synchronized, it first undergoes frame synchronization and frame header RM decoding, then the decoded data is modulated and stored, and then the data is processed frame by frame. A frame of data is taken and deframed to obtain the frame header SOF information, PLSC information and pilot signal, and the SOF information is conjugate multiplied with the locally stored SOF information to remove the phase information of the modulated signal:

[0070]

[0071] in, The first phase information after removing the modulation signal for SOF information, To receive the SOF signal, For local storage A SOF signal. The length of the SOF symbol is 26. is the modulation signal amplitude (A=1). For the The first The modulation phase of the transmitting SOF signal, is the residual frequency offset information after coarse frequency offset compensation, is the system sampling rate, is the noise signal received by the receiving end, is the length of a data frame, j is the imaginary unit, is the phase of the SOF information noise.

[0072] Conjugate and multiply the frame header PLSC information with the locally stored PLSC information to remove the phase information of the modulated signal:

[0073]

[0074] In the above formula, For the 64 PLSC signals received, For the 64 PLSC signals stored locally, the first 63 data are taken for calculation. The length of the PLSC symbol is 64. is the modulation signal amplitude (A=1), The first phase information after removing the modulation signal for PLSC information, is the phase of the PLSC information noise. For the The first The modulation phase of the transmitting PLSC signal.

[0075] Step S102: Accumulate and sum the first phase information and the second phase information based on the number of frame header symbols in the data frame to obtain a first phase value and a second phase value.

[0076] It can be understood that, considering the existence of residual frequency offset and phase noise, by accumulating and summing the first phase information and the second phase information, the phase information of all frame header symbols in the data frame can be fully utilized. The accumulation operation can smooth out the influence of random noise and interference on the phase of a single symbol, thereby improving the overall accuracy of phase estimation.

[0077] In one example, the processed data of the processed SOF symbol is accumulated, and a first phase value is obtained from the accumulated data. ,get:

[0078]

[0079] Taking into account the existence of residual frequency offset and phase noise, the phase estimated by the above formula is only the average phase in the SOF block, which can be considered as the phase at the middle SOF. At this time, the phase value of the 13th symbol in the SOF symbol is obtained by calculation.

[0080] The processed data of the processed PLSC symbol is accumulated, and the phase value is obtained from the accumulated data to obtain the second phase value :

[0081]

[0082] Taking into account the existence of residual frequency offset and phase noise, the phase estimated by the above formula is only the average phase within the PLSC block, which can be considered as the phase at the middle PLSC. At this time, the phase value of the 33rd symbol in the PLSC symbol is obtained by calculation.

[0083] Step S103: calculating the phase difference of the frame header information according to the first phase value and the second phase value, and determining the linear interpolation phase step based on the phase difference and the interval data.

[0084] It is understandable that when calculating the phase difference of the frame header information based on the first phase value and the second phase value, if a phase jump occurs in the processed phase difference, the phase difference needs to be post-processed accordingly, and then the linear interpolation phase step is determined based on the phase difference and the interval data.

[0085] In one example, the phase difference between SOF and PLSC is:

[0086]

[0087] At this time, according to the data frame structure, the interval between SOF and PLSC is ; The phase change step caused by the frequency deviation can be obtained as :

[0088]

[0089] Of course, in order to quickly and accurately obtain SOF information and PLSC information and improve the efficiency of data frame processing, before step S101, it also includes: collecting the received signal when there is residual frequency deviation; performing frame synchronization and frame header decoding on the received signal to obtain a data frame, and de-framing the data frame to obtain SOF information and PLSC information.

[0090] It should be understood that residual frequency deviation refers to the frequency deviation that still exists after frequency correction during the signal reception process. This deviation may be caused by factors such as frequency mismatch between the transmitter and the receiver, frequency distortion or noise interference in the channel. The received signal refers to the electromagnetic wave signal transmitted from the transmitter through the antenna or other receiving device. After these signals are transmitted through the channel, they will be affected by attenuation, noise interference and distortion. Frame synchronization refers to the ability of the receiving end to accurately identify and synchronize to the starting position of the data frame sent by the sending end in a digital communication system. Frame header decoding refers to the decoding of the frame header part of the received data frame to extract the information carried in the frame header, such as frame type, frame length, source address and destination address.

[0091] In one example, when there is residual frequency deviation in the received signal, Packet reception signal It can be expressed as:

[0092]

[0093] In the above formula For the The first The modulation phase of the transmitting signal, is the residual frequency offset information after coarse frequency offset compensation, is the system sampling rate, is the noise signal received by the receiving end, is the length of a data frame. j is the imaginary unit. is the phase of the noise.

[0094] After the received signal is synchronized, it first undergoes frame synchronization and frame header RM decoding, then the decoded data is modulated and stored, and then the data is processed frame by frame. A frame of data is taken and deframed to obtain the frame header SOF information, PLSC information and pilot signal.

[0095] Of course, in order to determine the frequency deviation range that the system can handle and improve the adaptability of the system, after step S103, it also includes: when there is a phase jump in the phase difference, adjusting the phase difference according to a preset adjustment period to obtain the target phase; calculating based on the target phase, the interval data and the system sampling rate to obtain the maximum frequency deviation range that can be handled.

[0096] It is understandable that when a phase difference jump is detected (i.e., the phase difference suddenly changes significantly), the phase difference needs to be adjusted according to a preset adjustment period. The adjustment period can be determined based on the stability requirements of the system, the provisions of the communication protocol, or the statistical results of experimental data. By adjusting the phase difference, it gradually approaches or reaches a predetermined target value, which is called the target phase. The determination of the target phase may depend on the specific requirements of the system, such as the communication rate, bit error rate, etc.

[0097] In one example, the processed phase If there is a phase jump, the phase needs to be processed:

[0098]

[0099] At this time, according to the data frame structure, the interval between SOF and PLSC is ; The phase change step caused by the frequency deviation can be obtained as:

[0100]

[0101] Through the calculated phase value, it can be seen from the above formula that the maximum frequency deviation range that this solution can handle is:

[0102]

[0103] It should be noted that when performing calculations, attention should be paid to the accuracy and reliability of the parameters. For example, the system sampling rate should be high enough to capture subtle changes in the signal; the interval data should accurately reflect the actual time interval between signals. In addition, the impact of factors such as signal noise and interference on the calculation results needs to be considered. In practical applications, multiple measurements and statistical analysis may be required to improve the accuracy of the calculation results.

[0104] In this embodiment, the SOF information and PLSC information in the frame header information are conjugate multiplied with the locally stored SOF signal and PLSC signal respectively to obtain the first phase information and the second phase information; the first phase information and the second phase information are cumulatively summed based on the number of frame header symbols in the data frame to obtain the first phase value and the second phase value; the phase difference of the frame header information is calculated based on the first phase value and the second phase value, and the linear interpolation phase step is determined based on the phase difference and the interval data. By conjugate multiplying the SOF information and the PLSC information with the locally stored signal, the first phase information and the second phase information are obtained to remove the phase information of the modulated signal, and the existence of residual frequency offset and phase noise is taken into account, and an accurate estimation value is obtained, thereby improving the efficiency of data frame processing.

[0105] Reference Figure 5 , Figure 5 This is a flow chart of a third embodiment of a residual frequency offset compensation method of the present application. Based on the above second embodiment, a third embodiment of a residual frequency offset compensation method of the present application is proposed.

[0106] In this embodiment, the step S20 includes:

[0107] Step S201: determining a phase offset estimation value between pilot signals according to the linear interpolation phase step and the interval data.

[0108] It should be understood that the phase offset estimate refers to the estimated result of the signal phase offset in the signal processing or communication system, which can be calculated by a certain algorithm or method (such as linear interpolation, least squares method, Kalman filtering, etc.), and reflects the difference between the actual phase of the signal and the ideal phase.

[0109] It can be understood that, according to the linear interpolation phase step and the interval data, the phase offset estimation value between each pilot signal can be determined by using the known linear interpolation phase step to perform phase interpolation between two adjacent pilot signals according to a certain rule (such as equal interval, equal phase change, etc.), and then, in combination with the interval data between the pilot signals, the phase offset estimation value corresponding to each interpolation point is calculated. In one example, when the two phase change steps are In the case of , the phase change between the two pilots is:

[0110]

[0111] In the above formula, is the estimated phase offset between PLSC and the first pilot, For the The pilot and The phase offset estimation value between adjacent pilot blocks of a pilot. Len1 is the interval data between PLSC and the first pilot, and Len2 is the interval data between the first and second pilot blocks. The pilot and The pilot blocks contain the interval data between adjacent pilot blocks.

[0112] Step S202: round down the ratio of the phase offset estimation value to the interval data to obtain a phase change parameter.

[0113] It should be understood that the phase change parameter is a parameter used to describe whether the phase difference between two previous and next pilot signals will have a phase jump.

[0114] It is understandable that in actual signal processing or communication systems, due to hardware limitations, computational complexity, etc., it is usually necessary to quantize continuously changing signals. The ratio of the phase offset estimate to the interval data is rounded down, and the continuously changing phase offset is converted into a discrete phase change parameter. By rounding down, the subsequent calculation process can be simplified.

[0115] In one example, since the distance between pilots is relatively long and the frequency offset variation in the unknown system, the parameter is set , used to determine whether the phase difference between the two pilot signals will have a phase jump. The calculation formula is as follows:

[0116]

[0117] In the subsequent case of cycle skipping due to large residual frequency deviation, the parameters , to make corresponding compensation.

[0118] In this embodiment, the step S30 includes:

[0119] Step S301: Calculate a first phase interpolation of the medians of two preceding and succeeding pilot signals based on the phase offset estimation value.

[0120] It should be understood that when the phase offset between two pilot signals (or pilot points) is known or estimated, in order to more accurately describe the phase change between the two pilot signals, it is often necessary to insert one or more additional phase points between them. These additionally inserted phase points are called phase interpolation points. The interpolation points are usually located near the midpoint of the two pilot signals (but not necessarily exactly at the midpoint), and their phase values ​​are calculated by some interpolation algorithm (such as linear interpolation, quadratic interpolation, etc.).

[0121] It is understandable that, when it is detected that the calculated first phase interpolation value has a phase jump, its phase also needs to be processed.

[0122] In one example, the formula for calculating the first phase interpolation of the median values ​​of the two preceding and succeeding pilot signals is as follows:

[0123]

[0124] in, For the The pilot and The estimated value of the phase offset between adjacent pilot blocks, For the The pilot and The estimated value of the phase offset between adjacent pilot blocks, is the initial phase interpolation. When detecting that the calculated first phase interpolation value has a phase jump, the initial phase interpolation value is processed to obtain the first phase interpolation value.

[0125] Step S302: When it is detected that the phase offset estimation value has a phase cross-cycle, corresponding cycle skip compensation is performed on the first phase interpolation according to the phase change parameter to obtain a second phase interpolation.

[0126] It should be understood that the phase cross cycle will cause the continuity of the phase information to be destroyed. Cycle skip compensation can restore the continuity of the phase and make the phase information more accurate. In digital communication systems, phase errors may cause the generation and propagation of bit errors. Cycle skip compensation can reduce the phase error, thereby reducing the bit error rate and improving the reliability of the system.

[0127] It can be understood that when a phase cross-cycle is detected, the phase change parameter can be used to determine the number and direction of the cycle jump, so as to perform corresponding compensation on the first phase interpolation.

[0128] In one example, due to the large residual frequency offset, , If there is a skip cycle, Perform phase jump compensation, the specific changes are as follows:

[0129]

[0130] in, It is the phase difference caused by frequency deviation between the two pilot tones before and after the cycle jump.

[0131] Step S303, dividing the second phase interpolation and the interval data to obtain a linear phase interpolation step value, and considering the initial phase, performing segmented compensation on the data segments in the data frame based on the linear phase interpolation step value and the phase offset estimation value to obtain modulated data phase information.

[0132] It should be noted that the linear phase interpolation step value refers to the phase change per unit time (or space) between two known phase points (such as the phase of two pilot signals) calculated by linear interpolation. Segmented compensation is to divide the data into multiple segments according to a certain rule in data processing, and then perform compensation processing on each segment to improve data quality when the data may be affected by various factors (such as noise, interference, distortion, etc.), resulting in a decrease in data quality.

[0133] For ease of understanding, the following examples are provided, but are not intended to limit the present application. Figure 6 , Figure 6 This is a block diagram for the implementation of the residual frequency offset compensation algorithm of the present application. In the figure, PLSC symbols and SOF numbers are extracted from the received data frame. They are used to perform conjugate multiplication with the locally stored PLSC symbols and SOF symbols to estimate the data phase. Next, the process enters the phase jump processing stage to calculate the phase interpolation step, which is to compensate for the phase changes that may occur in the signal during transmission. Then, the pilot block phase difference is calculated, which involves analyzing the phase changes of the data symbols between the pilot blocks to determine the changes in the phase difference. After obtaining the change in the phase difference, data segment phase compensation is continued, and the data symbol phase step value between the pilot blocks is calculated by linear interpolation, thereby achieving phase compensation for the entire data segment.

[0134] The phase interpolation step value between two pilot blocks obtained after cycle skip compensation is:

[0135]

[0136] in =18+1440+18=1476; is the phase difference between the two pilot signals due to the residual frequency offset. Then, the data is linearly interpolated to obtain the phase interpolation result between the two pilot signals.

[0137]

[0138] Then the data phase is compensated. The compensation is segmented and the initial phase must be considered. Phase compensation is performed on the middle data segment as shown below:

[0139]

[0140] Finally, according to the calculated phase step value And the obtained phase value , segmented compensation modulation data phase Through the simulation of the algorithm, the proposed compensation scheme can compensate for the residual frequency deviation of 1 / 45 of the symbol rate under low signal-to-noise ratio and low symbol rate conditions, especially when there is a changing Doppler, and can correctly restore the phase information of the modulated data.

[0141] In this embodiment, the ratio of the phase offset estimate to the interval data is rounded down to obtain a phase change parameter, which optimizes the phase change parameter acquisition process and provides accurate parameters for subsequent phase compensation. The data is used to calculate the phase difference to determine the residual frequency deviation and the frame header position. When the phase cross-cycle is detected, phase compensation is performed and the linear phase interpolation step value is calculated, thereby restoring high-order modulated data without distortion under complex conditions.

[0142] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the residual frequency offset compensation method of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0143] The present application also provides a residual frequency offset compensation device, please refer to Figure 7 , the residual frequency offset compensation device comprises:

[0144] A step length calculation module 10, used to determine a linear interpolation phase step length according to frame header information in a data frame;

[0145] An offset estimation module 20, configured to calculate a phase offset estimation value and a phase variation parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame;

[0146] The frequency offset compensation module 30 is used to compensate the phase offset estimation value according to the phase change parameter to obtain the modulated data phase when it is detected that the phase offset estimation value crosses the phase cycle.

[0147] The residual frequency offset compensation device provided by the present application adopts the residual frequency offset compensation method in the above-mentioned embodiment, which can solve the current technical problem in low-orbit satellite communication systems that, under the conditions of low symbol rate and low signal-to-noise ratio, if fewer pilot blocks are used to make the carrier precise synchronization converge quickly, a larger residual frequency offset will cause the phase difference between adjacent pilot blocks to cross-cycle, making it impossible for the receiver to correctly estimate the residual frequency offset and phase offset, resulting in a decrease in the demodulation performance of the receiver. Compared with the prior art, the beneficial effects of the residual frequency offset compensation device provided by the present application are the same as the beneficial effects of the residual frequency offset compensation method provided by the above-mentioned embodiment, and the other technical features in the residual frequency offset compensation device are the same as the features disclosed in the above-mentioned embodiment method, which will not be repeated here.

[0148] The present application provides a residual frequency offset compensation device, which includes: at least one processor; and a memory that is communicatively connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the residual frequency offset compensation method in the above-mentioned embodiment.

[0149] Reference below Figure 8 , which shows a schematic diagram of the structure of a residual frequency offset compensation device suitable for implementing the embodiment of the present application. The residual frequency offset compensation device in the embodiment of the present application may include but is not limited to mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), PMPs (Portable Media Players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 8 The residual frequency offset compensation device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0150] like Figure 8As shown, the residual frequency offset compensation device may include a processing device 1001 (such as a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the residual frequency offset compensation device are also stored. The processing device 1001, ROM1002 and RAM1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems can be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the residual frequency offset compensation device to communicate wirelessly or wired with other devices to exchange data. Although the residual frequency offset compensation device with various systems is shown in the figure, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or have alternatively.

[0151] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0152] The residual frequency offset compensation device provided by the present application adopts the residual frequency offset compensation method in the above embodiment, which can solve the current technical problem in low-orbit satellite communication systems that, under the conditions of low symbol rate and low signal-to-noise ratio, if fewer pilot blocks are used to make the carrier precise synchronization converge quickly, a larger residual frequency offset will cause the phase difference between adjacent pilot blocks to cross-cycle, making it impossible for the receiver to correctly estimate the residual frequency offset and phase offset, resulting in a decrease in the demodulation performance of the receiver. Compared with the prior art, the beneficial effects of the residual frequency offset compensation device provided by the present application are the same as the beneficial effects of the residual frequency offset compensation method provided in the above embodiment, and the other technical features in the residual frequency offset compensation device are the same as the features disclosed in the method of the previous embodiment, which will not be repeated here.

[0153] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0154] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0155] The present application provides a computer-readable storage medium having computer-readable program instructions (ie, computer programs) stored thereon, and the computer-readable program instructions are used to execute the residual frequency offset compensation method in the above-mentioned embodiment.

[0156] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM: Random Access Memory), a read-only memory (ROM: Read Only Memory), an erasable programmable read-only memory (EPROM: Erasable Programmable Read Only Memory or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM: CD-Read Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency: Radio Frequency), etc., or any suitable combination of the above.

[0157] The computer-readable storage medium may be included in the residual frequency offset compensation device; or may exist independently without being assembled into the residual frequency offset compensation device.

[0158] The computer-readable storage medium carries one or more programs. When the one or more programs are executed by the residual frequency offset compensation device, the residual frequency offset compensation device executes the residual frequency offset compensation method described above.

[0159] Computer program code for performing the operations of the present application may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0160] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0161] The modules involved in the embodiments described in this application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0162] The readable storage medium provided by the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned residual frequency offset compensation method, and can solve the current technical problem in low-orbit satellite communication systems that, under the conditions of low symbol rate and low signal-to-noise ratio, if fewer pilot blocks are used to make the carrier precise synchronization converge quickly, a larger residual frequency offset will cause the phase difference between adjacent pilot blocks to cross-cycle, making it impossible for the receiver to correctly estimate the residual frequency offset and phase offset, resulting in a decrease in the demodulation performance of the receiver. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present application are the same as the beneficial effects of the residual frequency offset compensation method provided by the above-mentioned embodiment, which will not be repeated here.

[0163] The present application also provides a computer program product, including a computer program, which implements the steps of the residual frequency offset compensation method as described above when the computer program is executed by a processor.

[0164] The computer program product provided by the present application can solve the technical problem that in the current low-orbit satellite communication system, under the conditions of low symbol rate and low signal-to-noise ratio, if fewer pilot blocks are used to make the carrier precise synchronization converge quickly, a large residual frequency offset will cause the phase difference between adjacent pilot blocks to cross the cycle, making it impossible for the receiver to correctly estimate the residual frequency offset and phase offset, resulting in a decrease in the demodulation performance of the receiver. Compared with the prior art, the beneficial effects of the computer program product provided by the present application are the same as the beneficial effects of the residual frequency offset compensation method provided in the above embodiment, which will not be repeated here.

[0165] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A residual frequency offset compensation method, characterized in that: The residual frequency offset compensation method comprises: Determine the linear interpolation phase step according to the frame header information in the data frame; Calculate a phase offset estimation value and a phase change parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame; When it is detected that the phase shift estimation value has a phase cross cycle, the phase shift estimation value is compensated according to the phase change parameter to obtain the modulation data phase information; The step of calculating the phase offset estimation value and the phase change parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame comprises: Determine a phase offset estimate between pilots based on the linear interpolation phase step and the spacing data; The ratio of the phase offset estimate to the interval data is rounded down to obtain a phase change parameter.

2. The residual frequency offset compensation method according to claim 1, characterized in that: The step of compensating the phase offset estimation value according to the phase change parameter to obtain the phase information of the modulated data when it is detected that the phase offset estimation value crosses the phase cycle includes: Calculate a first phase interpolation of the medians of two preceding and succeeding pilot signals based on the phase offset estimation value; When it is detected that the phase offset estimation value has a phase cross cycle, performing corresponding cycle skip compensation on the first phase interpolation according to the phase change parameter to obtain a second phase interpolation; The second phase interpolation value is divided by the interval data to obtain a linear phase interpolation step value, and considering the initial phase, the data segments in the data frame are segmentedly compensated based on the linear phase interpolation step value and the phase offset estimation value to obtain modulated data phase information.

3. The residual frequency offset compensation method according to claim 1, characterized in that: The frame header information includes SOF information and PLSC information; The step of determining the linear interpolation phase step according to the frame header information in the data frame comprises: Conjugate-multiply the SOF information and the PLSC information in the frame header information with the locally stored SOF signal and the PLSC signal respectively to obtain first phase information and second phase information; Accumulate and sum the first phase information and the second phase information based on the number of frame header symbols in the data frame to obtain a first phase value and a second phase value; The phase difference of the frame header information is calculated according to the first phase value and the second phase value, and a linear interpolation phase step is determined based on the phase difference and the interval data.

4. The residual frequency offset compensation method according to claim 3, characterized in that: Before the step of conjugating and multiplying the SOF information and the PLSC information in the frame header information with the locally stored SOF signal and the PLSC signal respectively to obtain the first phase information and the second phase information, the method further includes: Acquiring received signals when there is residual frequency offset; The received signal is subjected to frame synchronization and frame header decoding to obtain a data frame, and the data frame is subjected to frame de-framing processing to obtain SOF information and PLSC information.

5. The residual frequency offset compensation method according to claim 3, characterized in that: After the step of calculating the phase difference of the frame header information according to the first phase value and the second phase value, and determining the linear interpolation phase step based on the phase difference and the interval data, the method further includes: When there is a phase jump in the phase difference, adjusting the phase difference according to a preset adjustment period to obtain a target phase; A calculation is performed based on the target phase, the interval data and the system sampling rate to obtain a maximum processable frequency deviation range.

6. A residual frequency offset compensation device, characterized in that: The device comprises: A step length calculation module, used for determining a linear interpolation phase step length according to frame header information in a data frame; An offset estimation module, used for calculating a phase offset estimation value and a phase change parameter based on the linear interpolation phase step and the interval data between any two pilots in the data frame; A frequency offset compensation module, configured to compensate the phase offset estimation value according to the phase change parameter to obtain a modulated data phase when it is detected that the phase offset estimation value crosses a phase cycle; The offset estimation module is further used to determine the phase offset estimation value between each pilot tone according to the linear interpolation phase step and the interval data; The ratio of the phase offset estimate to the interval data is rounded down to obtain a phase change parameter.

7. A residual frequency offset compensation device, characterized in that: The device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the residual frequency offset compensation method according to any one of claims 1 to 5.

8. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the residual frequency offset compensation method according to any one of claims 1 to 5 are implemented.

9. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the residual frequency offset compensation method according to any one of claims 1 to 5 are implemented.

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