Method, apparatus, and device for aligning UAV communication signals in complex channels

Abstract

Embodiments of the present application provide a method, apparatus, and device for aligning UAV communication signals in a complex channel. The method includes performing matched filtering on signal data to obtain optimized signal data; performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code in the preamble; borrowing the same number of chips as the unique word chips in the preamble to combine with the unique word to obtain a combined unique word; based on the starting position of the pseudo-code period in the preamble, correlating with the combined unique word, and after the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word; based on the starting position of the unique word, performing initial carrier synchronization through the preamble and the unique word, correcting the frequency offset of the signal data, and performing demodulation output after the correction is completed. In this way, stable communication in a complex channel environment is achieved.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of communications, and in particular, to a method, apparatus, and device for aligning UAV communication signals in complex channels. Background Art

[0002] In view of the requirements of various operations for UAV systems, how to enable the UAV measurement and control system to achieve reliable transmission of information in non-line-of-sight paths in cities, long-distance suburban channels, and dense forest environments, that is, in harsh urban complex channel environments without line-of-sight paths, low transmission power, and long transmission distances, and under low signal-to-noise ratio conditions, that is, how to achieve fast and accurate data synchronization in complex channels, is an urgent problem to be solved currently. Summary of the Invention

[0003] According to an embodiment of the present application, a solution for aligning UAV communication signals in complex channels is provided.

[0004] In a first aspect of the present application, a method for aligning UAV communication signals in complex channels is provided. The method includes:

[0005] Performing matched filtering on signal data to obtain optimized signal data; the frame structure of the signal data includes a preamble, a unique word, and data;

[0006] Performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code period in the preamble;

[0007] Combining the same number of chips as the unique word chips in the preamble with the unique word to obtain a combined unique word;

[0008] Based on the starting position of the pseudo-code period in the preamble, performing correlation with the combined unique word. After the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word;

[0009] Based on the starting position of the unique word, performing initial carrier synchronization through the preamble and the unique word to obtain an initial frequency offset and an initial phase offset;

[0010] Based on the initial frequency offset and the initial phase offset, performing frequency offset correction on the signal data, and after the correction is completed, performing demodulation output.

[0011] Further, the performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code in the preamble includes:

[0012] Performing sliding correlation on the pseudo-code in the preamble and calculating the signal peak-to-average ratio;

[0013] Based on the peak-to-average ratio of the signal and the absolute value threshold, determine the initial phase time of the pseudo-code, and obtain the starting position of the pseudo-code in the preamble.

[0014] Further, it further includes:

[0015] When calculating the peak-to-average ratio of the signal, the current signal and every n*TP points before the current signal are not involved in the calculation.

[0016] Further, the method for performing burst fine capture on the optimized signal data through an asymmetric threshold decision after correlating the starting position of the pseudo-code period in the preamble with the joint unique word to obtain the starting position of the unique word includes:

[0017] Based on the starting position of the pseudo-code period in the preamble, perform correlation with the joint unique word every other pseudo-code period; the length of the correlation is the number of chips of the joint unique word;

[0018] Based on the chips after the correlation is completed, perform burst fine capture on the optimized signal data through an asymmetric threshold decision to determine the starting position of the unique word.

[0019] Further, the initial frequency offset is calculated by the following formula:

[0020]

[0021] where is the frequency point searched by f;

[0022] L is the number of sampling points;

[0023] r k is the data used for estimation;

[0024] T b is the sampling rate.

[0025] Further, the initial phase offset is calculated by the following formula:

[0026]

[0027] where angle represents the calculated phase.

[0028] Further, the signal data includes:

[0029] Single-bit data quantized to [1, -1].

[0030] In the second aspect of the present application, a device for aligning UAV communication signals under complex channels is provided. The device includes:

[0031] An optimization module for performing matched filtering on signal data to obtain optimized signal data; the frame structure of the signal data includes a preamble, a unique word, and data;

[0032] A first capture module for performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code in the preamble;

[0033] A second capture module for combining the unique word with the same number of chips as the unique word in the preamble to obtain a combined unique word; based on the starting position of the pseudo-code period in the preamble, correlating with the combined unique word, and after the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word;

[0034] A calculation module for performing initial carrier synchronization through the preamble and the unique word based on the starting position of the unique word to obtain an initial frequency offset and an initial phase offset;

[0035] A correction module for performing frequency offset correction on the signal data based on the initial frequency offset and the initial phase offset, and performing demodulation output after the correction is completed.

[0036] In the third aspect of the present application, an electronic device is provided. The electronic device includes: a memory and a processor, a computer program is stored on the memory, and when the processor executes the program, the method described above is implemented.

[0037] In the fourth aspect of the present application, a computer-readable storage device is provided, on which a computer program is stored, and when the program is executed by a processor, the method according to the first aspect of the present application is implemented.

[0038] The method for aligning UAV communication signals in a complex channel provided by the embodiments of the present application obtains optimized signal data by performing matched filtering on signal data; the frame structure of the signal data includes a preamble, a unique word, and data; performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code period in the preamble; combining the unique word with the same number of chips as the unique word in the preamble to obtain a combined unique word; based on the starting position of the pseudo-code period in the preamble, correlating with the combined unique word, and after the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word; performing initial carrier synchronization through the preamble and the unique word based on the starting position of the unique word to obtain an initial frequency offset and an initial phase offset; performing frequency offset correction on the signal data based on the initial frequency offset and the initial phase offset, and performing demodulation output after the correction is completed, and accurate fine synchronization can still be achieved when there is a sampling frequency deviation in the system.

[0039] It should be understood that the content described in the Summary of the Invention section is not intended to limit the key or important features of the embodiments of the present application, nor to limit the scope of the present application. Other features of the present application will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In conjunction with the accompanying drawings and with reference to the following detailed description, the above and other features, advantages, and aspects of the embodiments of the present application will become more apparent. In the drawings, the same or similar reference numerals denote the same or similar elements, where:

[0041] Figure 1 is a flowchart of a method for aligning UAV communication signals in a complex channel according to an embodiment of the present application;

[0042] Figure 2 is a schematic diagram of the frame structure of a burst spread spectrum communication system according to an embodiment of the present application;

[0043] Figure 3 is a schematic diagram of burst coarse acquisition according to an embodiment of the present application;

[0044] Figure 4 is a schematic diagram of auxiliary word synchronization acquisition according to an embodiment of the present application;

[0045] Figure 5 is a schematic diagram of the correlation peak-to-average ratio according to an embodiment of the present application;

[0046] Figure 6 is a schematic diagram of calculating the mean power using a FIFO according to an embodiment of the present application;

[0047] Figure 7 is a schematic diagram of an extended unique word according to an embodiment of the present application;

[0048] Figure 8 is a schematic diagram of fine synchronization according to an embodiment of the present application;

[0049] Figure 9 is a schematic diagram of the correlation peak point according to an embodiment of the present application;

[0050] Figure 10 is a schematic diagram of a carrier synchronization structure based on a frequency offset estimation and compensation algorithm according to an embodiment of the present application;

[0051] Figure 11 is a block diagram of a device for aligning UAV communication signals in a complex channel according to an embodiment of the present application;

[0052] Figure 12 is a schematic diagram of a terminal device or a server suitable for implementing the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0054] In addition, the term "and / or" in this article is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the preceding and following associated objects.

[0055] Term Explanation:

[0056] Coarse synchronization and fine synchronization:

[0057] Synchronization technology is usually completed in two steps: coarse synchronization and fine synchronization. The specific method is to capture and search for the synchronization sequence in an indefinite time window, perform circular correlation on the synchronization sequence, and when the peak value exceeds a certain level, it can be determined that the two are aligned; then select a detection and search algorithm suitable for the synchronization header structure to process the correlation value and determine whether the capture is successful. If the search terminates at a certain point, it can be regarded as successful coarse synchronization. It should be noted that coarse synchronization does not necessarily find the true synchronization starting point.

[0058] Further, after coarse synchronization is completed, enter the fine synchronization tracking process, that is, perform circular correlation processing on the subsequent two sequences and their correlation values to further improve the synchronization accuracy or find the true starting point. Perform a correlation operation on the local modulated sequence signal corresponding to the received frequency hopping synchronization header. Within the detection time window, if the correlation value does not exceed the threshold level, the capture fails and continue to search; if the correlation value output within the detection time window exceeds the threshold level, the capture is successful, coarse synchronization is completed, stop searching, and the system enters the tracking state.

[0059] Further, in the tracking state, that is, continue to check whether the correlation value output exceeds the threshold level within a certain time range. The time range at this time is smaller than that of coarse synchronization. If the condition is met, fine synchronization is completed, and the subsequent demodulation work starts from the data start position.

[0060] Figure 1 The flowchart of a method for aligning UAV communication signals in a complex channel according to an embodiment of the present disclosure is shown. The method includes:

[0061] S110, perform matched filtering on the signal data to obtain optimized signal data.

[0062] In some embodiments, the present disclosure can be applied to systems such as burst spread spectrum communication and continuous spread spectrum. The frame structure adopted is as Figure 2 shown, including a preamble (auxiliary synchronization word), a unique word, and data.

[0063] The values of the preamble, unique word, and data are non-fixed values and can be determined according to different application scenarios.

[0064] For the convenience of explaining the present disclosure, taking the assignment in Figure 2 as an example, the chip rate is set to 10 Mcps at the same time;

[0065] The maximum Doppler frequency offset is ±5 kHz;

[0066] ADC sampling rate: 40 MHz (4 times sampling) or 80 MHz (8 times sampling);

[0067] Processing clock frequency: 80 MHz.

[0068] It should be noted that the above settings (assignments) can be adjusted according to the actual application scenario.

[0069] In some embodiments, referring to Figure 2 , there is a preamble of 32 * 128 = 4096 chips in front of each burst, the content of which is 32 known pseudo-codes repeated 128 times; then there is a known unique word of 1024 chips; finally, there is data, which can adopt one of 64 / 32 / 16 times spreading (spreading ratio), corresponding to 1280 / 2560 / 5120 symbols respectively; it should be noted that the length of the data symbol and the spreading ratio are not limited, and the above values are only for illustrative purposes.

[0070] In some embodiments, first, the signal data obtained by ADC sampling is subjected to matched filtering to filter out out-of-band noise and maximize the signal energy, obtaining optimized signal data.

[0071] Among them, the form of the matched filter depends on the form of the shaping filter at the transmitting end. If the transmitting end is rectangular shaping, the matched filter is also a rectangular filter. If the transmitting end is root-raised cosine shaping, the matched filter is also a root-raised cosine filter.

[0072] S120. Perform burst rough capture on the optimized signal data to obtain the starting position of the pseudo-code in the preamble.

[0073] Among them, burst rough capture is a process of performing sliding correlation using a spread spectrum pseudo-code. Once the correlation peak exceeds the threshold, the initial code phase time of the spread spectrum codeword in the received signal can be accurately obtained, that is, the starting position of the 32-bit long pseudo-code.

[0074] Specifically, referring to Figure 3 :

[0075] The spreading code pseudo - code period is TP = 32. That is, when capturing, it takes at most the time to search for TP = 32 pseudo - code phases. That is, the synchronization crossing accuracy is 32 symbols. The search is carried out by the data segmentation method. Each time, the time for correlation is the time of 16 segments of pseudo - code (16 pseudo - code periods), 16 * 32 = 512 chips.

[0076] Each segment of data is searched for 17.5 chips of time. After completing the search of one segment of data, it enters the waiting state. When the next segment of data is received in full, the search starts again until the correlation peak exceeds the threshold and the capture is completed.

[0077] Further, when searching for 17.5 chips in each segment of data, correlation is carried out at intervals of T c / 4 within each chip. That is, a total of 17.5T c ÷T c / 4 = 70 correlation values at time points are required for each segment of data.

[0078] Further, for each correlation, it can be implemented by an accumulator. The accumulator accumulates the received data at chip intervals according to the known pseudo - code period, and calculates its modulus value as the correlation value after accumulation; it takes 32 * 16 = 512 clock cycles to complete one correlation. At a processing clock frequency of 80 MHz, there are 32 * 16 * 8 = 4096 clock cycles available for one segment of data. Considering the processing overhead, one correlator can complete 7 correlation calculations within this time. That is, 70 / 7 = 10 correlators are required for parallel search.

[0079] Further, since the maximum frequency offset is only ±5 kHz, the phase rotation generated during the correlation time is only 2π * 32 * 16 * 5 kHz / 10 MHz = 0.512π, and the loss of the correlation value is about 1 dB, which is very small. Therefore, it is not necessary to search in the frequency - offset domain anymore.

[0080] Further, since the capture pseudo - code period is 1024 chips, the anti - noise ability is slightly insufficient. Therefore, the auxiliary word can use 2048 chips (the unique word 1024 borrows a part of the auxiliary word 1024 to also reach a length of 2048, and the lengths need to be unified) at low SNR. That is, 48 pseudo - code periods, 48 * 32 = 2048 chips. At the same time, in order to save resources, the received data can be quantized only to [1, - 1], the received data is single - BIT, and the local data is also single - BIT, so as to reduce the data bit - width and at the same time increase the number of correlation points to enhance the anti - interference performance.

[0081] After simulation experiments, after becoming single BIT, the anti-noise ability is reduced by 2 dB, the length increases to 4 times, and the anti-noise ability is improved by 6 dB, achieving an obvious improvement effect.

[0082] Further, referring to Figure 4 , there are two conditions for assisting the word capture decision:

[0083] The first one is Figure 4 the peak-to-average ratio shown in

[0084] , that is, the mean value PowAVER of the received signal is multiplied by a peak-to-average ratio PAR, THR1 = PowAVER * PAR; Figure 4 The second one is

[0085] the absolute value threshold shown in Figure 5 and Figure 6 . When calculating the peak-to-average ratio of the signal, the current signal and every n * TP = 32n (n = 0, 1, 2,... N) points before the current signal do not participate in the mean value calculation. The TP part does not participate in the calculation to reduce the mean value at the moment when the peak arrives. At this time, a larger PAR can be obtained, greatly improving the capture probability; that is, the periodic peak points do not participate in the calculation when calculating the mean value, so that when encountering a real peak point, the mean power will not be too high.

[0086] S130, borrow the same number of chips as the unique word in the preamble and combine them with the unique word to obtain a combined unique word; based on the starting position of the pseudo-code period in the preamble, perform correlation with the combined unique word. After the correlation is completed, perform burst fine capture on the optimized signal data through an asymmetric threshold decision method to obtain the starting position of the unique word.

[0087] Among them, the combined unique word is composed of the unique word and the same number of chips as the unique word in the preamble.

[0088] For example, if the unique word includes 1024 chips, then borrow 1024 chips from the preamble and form 2048 chips after combination.

[0089] In some embodiments, the starting position of the unique word is determined by burst fine capture (using a unique word of 1024 chips). That is, according to the position found by coarse capture (the starting position of the 32-bit long pseudo-code), every 32 chips, that is, one pseudo-code period, the received data is correlated with the unique word, and the correlation time length is 1024 chips. If the correlation peak exceeds the threshold value, it is considered that the starting position of the unique word is found.

[0090] Further, in order to obtain a more accurate starting position, two sampling points before and after the current position on the capture can be used as starting points, and then two correlation values are calculated. The position with the largest correlation value among the three is taken as the final starting position to complete the fine capture.

[0091] Under normal circumstances, the chip offset caused by Doppler in the data phase is small. Therefore, the chips do not need to be tracked in the data phase. For example, there are 64 * 1280 = 81920 chips in the data part, and the maximum speed does not exceed Mach 1. At this time, the maximum chip offset caused by Doppler is 81920 * 340 / c = 0.093 chips, which is very small.

[0092] In some embodiments, referring to Figure 7 and Figure 8 , in order to further improve the synchronization anti-noise performance, when performing unique word synchronization, 1024 points in the auxiliary word are borrowed to complete the unique word synchronization. That is, 32 pseudo-code periods in the auxiliary word and the subsequent unique word are combined to form a combined unique word to achieve fine synchronization.

[0093] Specifically, when performing auxiliary word synchronization, the synchronization accuracy is 1 / 4 chip. After the auxiliary word synchronization is successful (32×64), combined synchronization is performed, that is, the synchronization is changed to the combined synchronization of the unique word and the auxiliary word, and 32 * 32 = 1024 auxiliary words and 1024 unique words are borrowed for combined synchronization. At this time, the synchronization accuracy is 32 chips. When the combined synchronization is successful, a peak tip appears (refer to Figure 9 ), and when the correlation peak (peak tip) meets the threshold, the fine synchronization is completed.

[0094] Further, based on the combined unique word (extended unique word), the correlation peak point is determined.

[0095] Specifically, referring to Figure 9 , the peak-to-average ratio (PAR) threshold of the left side (auxiliary word), the peak-to-average ratio threshold of the right side (1024 auxiliary words plus 1024 unique words), and the absolute value threshold are calculated respectively. The peak point when all three are satisfied is the required correlation peak point, and the starting position of the unique word is determined according to the correlation peak point. Among them, the peak-to-average ratio is the ratio of the sum of the squares of the maximum value of the transmitted signal to the average value of the square of the signal.

[0096] Further, referring to Figure 9 , the PAR calculation of left-right asymmetry is performed. The left PAR = 1.25 and the right PAR = 5. It can be seen that the right condition is more stringent. The reason is that there has been a matching auxiliary word in front of the left side, and the integrated power will be relatively high, while there is no matching auxiliary word integration on the right side. Therefore, different thresholds can be set to achieve the purpose of detecting the peak point.

[0097] S140. Based on the starting position of the unique word, perform initial carrier synchronization through the preamble and the unique word to obtain an initial frequency offset and an initial phase offset.

[0098] In some embodiments, based on a known preamble and a unique word, estimate the initial frequency offset. Based on the initial frequency offset, use a carrier synchronization algorithm based on frequency offset estimation and compensation to estimate the frequency offset, and then compensate the original signal. This operation is always performed during the demodulation process. Among them, the carrier synchronization structure based on the frequency offset estimation and compensation algorithm is as Figure 10 shown.

[0099] In some embodiments, use the maximum likelihood estimation algorithm to estimate the frequency offset. The data length used for estimation is 64 * 16 = 1024 chips, including 512 unique codes and 512 adjacent preambles.

[0100] Further, in order to reduce the computational amount, the data can be despread first and integrated according to a period of 64 chips, reducing the number of sampling points to 16 points and the sampling rate to 10 Mcps / 64 = 156.25 kHz. That is, perform SP integration according to a certain spreading ratio, and calculate (estimate) the frequency offset while reducing the sampling points and rate.

[0101] Further, the initial frequency offset is estimated in the following manner:

[0102] Among them, the initial frequency offset estimation uses the maximum likelihood algorithm. The searched frequency offset range is ±5 kHz, linear search is used, the search step is 0.2 kHz, and a total of 50 searches are performed. The frequency offset estimation value is (take the f value that makes the following calculation formula the largest):

[0103]

[0104] Among them, is the frequency point searched by f;

[0105] L is the number of sampling points (16);

[0106] r k is the data used for estimation (1 / 156.25 kHz);

[0107] T b is the sampling rate;

[0108] arg represents a set;

[0109] At this time, the maximum frequency offset estimation error is 0.2 kHz / 2 = 0.1 kHz, and the maximum phase offset generated within this section of data is 2π * 16 * 0.1 kHz / 1 / 156.25 kHz = 0.02048π = 3.68°, which has a very small impact on demodulation and can be ignored.

[0110] In some embodiments, based on the initial frequency offset, the initial phase offset is calculated by the following formula:

[0111]

[0112] wherein, the "angle" represents obtaining the phase.

[0113] S150. Based on the initial frequency offset and the initial phase offset, perform frequency offset correction on the signal data, and after the correction is completed, perform demodulation output.

[0114] In some embodiments, based on the initial frequency offset and the initial phase offset, perform frequency offset correction by the following formula:

[0115]

[0116] wherein, is the initial frequency offset;

[0117] is the initial phase offset.

[0118] In some embodiments, based on the frequency offset, perform compensation on the original signal, and this operation is always performed during the demodulation process. After the compensation is completed, perform demodulation output, refer to Figure 9 .

[0119] According to the embodiments of the present disclosure, the following technical effects are achieved:

[0120] Adopt the joint use of the auxiliary word and the unique word for synchronization capture. Complete coarse synchronization through the auxiliary word, and complete fine synchronization through the unique word in combination with part of the auxiliary word. When there is a sampling frequency deviation in the system, accurate fine synchronization can still be achieved, and at the same time, the anti-noise performance of the system is improved.

[0121] That is, through the method of the present disclosure, stable communication of the UAV measurement and control system in a harsh urban complex channel environment without a direct line-of-sight path, low transmission power, and long transmission distance is achieved.

[0122] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present application is not limited by the described action sequence, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to the present application.

[0123] The above is the introduction of the method embodiments. The following further illustrates the solution of the present application through device embodiments.

[0124] Figure 11The block diagram of the apparatus 1000 for aligning UAV communication signals under complex channels according to an embodiment of the present application is shown as Figure 11 shown, the apparatus 1100 includes:

[0125] An optimization module 1110, configured to perform matched filtering on signal data to obtain optimized signal data; the frame structure of the signal data includes a preamble, a unique word, and data;

[0126] A first capture module 1120, configured to perform burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code in the preamble;

[0127] A second capture module 1130, configured to combine the unique word with the same number of chips as the unique word in the preamble to obtain a combined unique word; based on the starting position of the pseudo-code in the preamble, combine the preamble and the unique word, and perform burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word;

[0128] A calculation module 1140, configured to perform initial carrier synchronization through the preamble and the unique word based on the starting position of the unique word to obtain an initial frequency offset and an initial phase offset;

[0129] A correction module 1150, configured to perform frequency offset correction on the signal data based on the initial frequency offset and the initial phase offset, and perform demodulation output after the correction is completed.

[0130] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the described modules can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0131] Figure 12 The structural schematic diagram of a terminal device or a server suitable for implementing the embodiments of the present application is shown.

[0132] As Figure 12 shown, the terminal device or the server includes a central processing unit (CPU) 1201, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 1202 or the program loaded from the storage section 1208 into the random access memory (RAM) 1203. In the RAM 1203, various programs and data required for the operation of the terminal device or the server are also stored. The CPU 1201, the ROM 1202, and the RAM 1203 are connected to each other through a bus 1204. The input / output (I / O) interface 1205 is also connected to the bus 1204.

[0133] The following components are connected to the I / O interface 1205: an input section 1206 including a keyboard, a mouse, etc.; an output section 1207 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc. and a speaker, etc.; a storage section 1208 including a hard disk, etc.; and a communication section 1209 including a network interface card such as a LAN card, a modem, etc. The communication section 1209 performs communication processing via a network such as the Internet. A drive 1210 is also connected to the I / O interface 1205 as required. A removable medium 1211 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc. is mounted on the drive 1210 as required so that a computer program read from the same can be installed into the storage section 1208 as required.

[0134] Specifically, according to an embodiment of the present application, the above method flow steps can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product which includes a computer program carried on a machine-readable medium, and the computer program includes program codes for performing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through the communication section 1209, and / or installed from the removable medium 1211. When the computer program is executed by a central processing unit (CPU) 1201, the above functions defined in the system of the present application are executed.

[0135] It should be noted that the computer-readable device shown in this application can be a computer-readable signal medium, a computer-readable storage medium, or any combination of the two. A computer-readable storage device can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples of a computer-readable storage device can 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), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this application, a computer-readable storage device can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium can include a data signal propagated in a baseband or as part of a carrier wave, which carries computer-readable program code. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on a computer-readable medium can be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0136] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram can represent a module, a program segment, or a part of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks can occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks shown can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0137] The units or modules involved in the embodiments described in this application can be implemented in software or in hardware. The described units or modules can also be provided in a processor. Among them, the names of these units or modules do not, in some cases, constitute a limitation on the units or modules themselves.

[0138] As another aspect, this application also provides a computer-readable storage medium, which can be included in the electronic device described in the above embodiments; or it can exist separately without being assembled into the electronic device. The above computer-readable storage medium stores one or more programs, and when the foregoing programs are executed by one or more processors, the methods described in this application are implemented.

[0139] The above description is only for the preferred embodiments of this application and the description of the technical principles applied. Those skilled in the art should understand that the scope of the application involved in this application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the foregoing inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions described in this application.

Claims

1. A method for aligning UAV communication signals under complex channels, characterized in that Including: Performing matched filtering on the signal data to obtain optimized signal data; the frame structure of the signal data includes a preamble, a unique word, and data; Performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code period in the preamble; Borrowing the same number of chips as the unique word in the preamble and combining them with the unique word to obtain a combined unique word; Based on the starting position of the pseudo-code period in the preamble, correlating with the combined unique word. After the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word; Based on the starting position of the unique word, performing initial carrier synchronization through the preamble and the unique word to obtain an initial frequency offset and an initial phase offset; Based on the initial frequency offset and the initial phase offset, correcting the frequency offset of the signal data. After the correction is completed, performing demodulation output; The performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code in the preamble includes: Performing sliding correlation on the pseudo-code in the preamble and calculating the signal peak-to-average ratio; when calculating the signal peak-to-average ratio, the current signal and every n*TP points before the current signal are not involved in the calculation; Based on the signal peak-to-average ratio and the absolute value threshold, determining the initial phase time of the pseudo-code to obtain the starting position of the pseudo-code in the preamble; the correlating with the combined unique word based on the starting position of the pseudo-code period in the preamble. After the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word includes: Based on the starting position of the pseudo-code period in the preamble, correlating with the combined unique word every other pseudo-code period; the length of the correlation is the number of chips of the combined unique word; Based on the chips after the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to determine the starting position of the unique word.

2. The method according to claim 1, wherein The initial frequency offset is calculated by the following formula: , where is the frequency point searched by f; L is the number of sampling points; rk is the data used for estimation; Tb is the sampling rate.

3. The method according to claim 2, characterized in that, The initial phase offset is calculated by the following formula: , where angle represents the calculated phase.

4. The method according to claim 3, characterized in that The signal data includes: Single-bit data quantized to [1, -1].

5. An apparatus for aligning UAV communication signals under complex channels, characterized in that, Including: An optimization module for performing matched filtering on the signal data to obtain optimized signal data; the frame structure of the signal data includes a preamble, a unique word, and data; A first capture module for performing burst coarse capture on the optimized signal data to obtain the starting position of the pseudo-code in the preamble; A second capture module for borrowing the same number of chips as the unique word in the preamble and combining them with the unique word to obtain a combined unique word; based on the starting position of the pseudo-code period in the preamble, correlating with the combined unique word. After the correlation is completed, performing burst fine capture on the optimized signal data by means of asymmetric threshold decision to obtain the starting position of the unique word; A calculation module, configured to perform initial carrier synchronization on the basis of the starting position of the unique word through the preamble and the unique word, so as to obtain an initial frequency offset and an initial phase offset; A correction module, configured to perform frequency offset correction on the signal data on the basis of the initial frequency offset and the initial phase offset, and perform demodulation output after the correction is completed; The obtaining of the starting position of the pseudo-code in the preamble by performing burst coarse capture on the optimized signal data includes: Performing sliding correlation on the pseudo-code in the preamble to calculate the signal peak-to-average ratio; when calculating the signal peak-to-average ratio, the current signal and every n*TP points before the current signal are not involved in the calculation; The performing of burst fine capture on the optimized signal data by correlating the starting position of the pseudo-code period in the preamble with the combined unique word and, after the correlation is completed, by means of an asymmetric threshold decision to obtain the starting position of the unique word includes: Correlating the starting position of the pseudo-code period in the preamble with the combined unique word every other pseudo-code period; the length of the correlation is the number of chips of the combined unique word; Performing burst fine capture on the optimized signal data by means of an asymmetric threshold decision on the basis of the chips after the correlation is completed to determine the starting position of the unique word.

6. An electronic device, comprising a memory and a processor, wherein a computer program is stored on the memory, characterized in that, When the processor executes the computer program, the method according to any one of claims 1 to 4 is implemented.

7. A computer-readable storage device having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

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