Decoding method and system for dual-mode secondary radar response signal

Abstract

The present invention discloses a method and system for decoding a dual-mode secondary radar reply signal. The method comprises: obtaining pulse signal information; if the pulse width is a first pulse width, performing MarkX reply signal decoding; and if the pulse width in the information is a second pulse width, performing S-mode reply signal decoding; MarkX reply signal decoding comprises buffering pulse signal information, performing MarkX reply signal framework calculation and discrimination, obtaining information of each pulse signal in the MarkX reply signal based on the discrimination result, and then performing MarkX reply signal decoding to obtain a decoded bit stream of the MarkX reply signal; and S-mode reply signal decoding comprises buffering information of four leading pulse signals, performing S-mode reply signal framework calculation and discrimination, and then continuing to obtain pulse signal information to perform S-mode reply signal decoding to obtain a decoded bit stream of the S-mode reply signal. The present invention can quickly and accurately obtain decoded information of secondary radar reply signals of different modes.

Description

Technical Field

[0001] The present invention relates to the field of information recognition technology, and in particular to a method and system for decoding a dual-mode secondary radar response signal. Background Art

[0002] The working principle of secondary radar is that the interrogator of the ground station sends a secondary radar interrogation signal to the aerial target. After receiving the secondary radar interrogation signal, the aerial target loads the aircraft information to synthesize a secondary radar reply signal and sends it to the ground station. After receiving the secondary radar reply signal, the ground station obtains the aircraft's identity, attributes, location, special code and other surveillance information and reports it, providing intelligence support for target monitoring and flight safety.

[0003] The processing of secondary radar reply signals involves pulse detection, pulse information extraction, and pulse information decoding. Previously, after pulse information extraction, the pulse information was stored. Then, the stored data was frame-matched according to the signal type. Once the frame match was achieved, the signal within the frame was determined to detect crosstalk and the crosstalk data was removed. The information pulse was then searched for within the frame pulse to achieve target decoding. This method, which first stores the matched frame pulse signals and then performs a one-by-one comparison based on the frame pulse information to complete the decoding, limits the device's processing power and efficiency. This method is difficult to adapt to the high-density reply signal airspace environment and can result in false alarms and missed detections.

[0004] Patent CN102298146A discloses a secondary radar signal decoding method. This method uses an adaptive threshold to control the decoding switch, determines signal validity, and completes the secondary radar frame decision. It then extracts information codes and confidence bits based on the pulse frame's characteristic information, performs data fusion, and completes decoding. This pipelined operation ensures high real-time decoding performance. However, it only decodes single-pulse response signals from Mode A / C and is not applicable to the widely used Mode S response signals. Furthermore, the decoding process converts the signal into code pulses, calculates their confidence, and then performs data fusion based on the number of interrogation responses and the confidence of the code pulses. The fusion criterion requires that the response rate and the confidence of the code pulses meet a certain level. The decoding result depends on the selected confidence level. A high confidence level results in insufficient fused data, while a low confidence level results in excessive impurities in the fused data, both of which affect accuracy and make it difficult to obtain a relatively accurate decoding result. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: In response to the technical problems existing in the prior art, the present invention provides a decoding method and system for dual-mode secondary radar response signals. According to the structural characteristics of different mode signals in the secondary radar response signals, corresponding decryption methods are adopted respectively, which can quickly and accurately obtain the decoding information of the secondary radar response signals of different modes.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] A method for decoding a dual-mode secondary radar response signal comprises the following steps:

[0008] S1) acquiring information of a pulse signal, and if the pulse width of the information is the first pulse width, executing step S2); if the pulse width of the information is the second pulse width, executing step S3);

[0009] S2) Buffering the pulse signal information, performing MarkX response signal frame calculation and discrimination, if the discrimination passes, obtaining information of each pulse signal in the MarkX response signal based on the discrimination result, decoding the MarkX response signal based on the information of each pulse signal, obtaining a decoded bit stream of the MarkX response signal, and returning to step S1) until the end;

[0010] S3) Buffering the pulse signal information, performing S-mode response signal frame calculation and judgment, if the judgment is passed, continuing to obtain the pulse signal information to perform S-mode response signal decoding to obtain a decoded bit stream of the S-mode response signal.

[0011] Furthermore, the specific steps of caching the pulse signal information in step S2) include:

[0012] Release the information of the pulse signal at the head position of the first buffer index, advance the indexes corresponding to the remaining pulse signal information in the first buffer by one position, save the information of the current pulse signal at the tail position of the first buffer index, and execute the steps of calculating and judging the MarkX response signal framework.

[0013] Furthermore, the steps of calculating and judging the MarkX response signal framework in step S2) specifically include:

[0014] S22a) Select the pulse signal pulse45 of the first buffer index target position m The information is used to calculate the pulse signal pulse45 m The information and the pulse signals pulse45 before the index target position in the first buffer area index The difference in arrival time TOAD in the information index ;

[0015] S22b) If there is a difference value TOAD within the preset first interval index , then the corresponding pulse signal pulse45 index and pulse signal pulse45 m The frame pulse of the MarkX response signal, pulse signal pulse45 indexInformation and pulse signal pulse45 m The information between each pulse signal pulse45 k The information is the pulse signal information between the frame pulses in the MarkX response signal. If the difference TOAD index If both are outside the preset first interval, return to step S1).

[0016] Furthermore, in step S2), the specific steps of decoding the MarkX response signal according to the information of each pulse signal include:

[0017] S23a) Calculate each pulse signal pulse45 respectively k Information and pulse signal pulse45 index The difference in arrival time in the information is obtained, and the difference is divided by the first preset value to obtain the calculation result dist corresponding to each pulse signal;

[0018] S23b) rounding off the calculated result dist to an integer and then subtracting 1 to obtain each pulse signal pulse45 k The decoded bitstream bitstream_Mark is initialized according to the information of the MarkX response signal, and the pulse signal pulse45 is k The corresponding element in the decoded bitstream bitstream_Mark is set to the target value;

[0019] S23c) Calculate the pulse signal pulse45 at the tail position of the first buffer index n Information and pulse signal pulse45 m The difference in arrival time TOAD in the information SPI , if the difference TOAD SPI In a preset second interval, the corresponding element of the SPI pulse of the MarkX response signal in the decoded bitstream bitstream_Mark is set to a target value.

[0020] Furthermore, the specific steps of caching the pulse signal information in step S3) include:

[0021] Release the information of the pulse signal at the head position of the second buffer index, advance the indexes corresponding to the remaining pulse signal information in the second buffer by one position, save the information of the current pulse signal at the tail position of the second buffer index, and execute the steps of calculating and judging the S-mode response signal framework.

[0022] Furthermore, the calculation and determination of the Mode S reply signal framework in step S3) specifically includes the following steps:

[0023] S32a) respectively calculating the difference in arrival time between the information of the pulse signal at the index head position of the second buffer area and the information of each pulse signal at the index other positions;

[0024] S32b) If the differences are all within the corresponding preset intervals, the pulse corresponding to the second buffer area is the leading pulse of the S-mode response signal, and the judgment is passed; otherwise, the process returns to step S1).

[0025] Furthermore, in step S3), the specific steps of continuing to obtain information of the pulse signal to decode the S-mode response signal include: continuing to obtain information of the pulse signal, updating the corresponding center point pulse according to the pulse width type and arrival time of the information i The value of the center point pulse i The corresponding comparison benchmark point ben i The comparison result of the values ​​of is used to obtain the value of each element in the decoded bit stream of the S-mode response signal.

[0026] Furthermore, before continuing to obtain the information of the pulse signal, the step of calculating the comparison reference point is also included, specifically including: according to the arrival time of the information of the pulse signal at the index head position of the second buffer area and the response data block length of the S mode response signal, the pulse of each center point is calculated. i The corresponding comparison benchmark point ben i , the function expression is as follows:

[0027] ben i =pulse500+8.25+(i-1)

[0028] In the above formula, i is the sequence number, 1≤i≤N, N is the response data block duration of the S-mode response signal, and pulse500 is the arrival time of the pulse signal information at the index head position of the second buffer area.

[0029] Further, continue to obtain the information of the pulse signal, and update the corresponding center point pulse according to the pulse width type and arrival time of the information i The value of the center point pulse i The corresponding comparison point ben i The step of obtaining the value of each element in the decoded bit stream of the Mode S response signal based on the comparison result of the values ​​of

[0030] S33a) initializing a decoded bitstream bitstream_S of the S-mode response signal according to the response information of the S-mode response signal;

[0031] S33b) obtains information of the current pulse signal, and if the pulse width of the information is the second pulse width, executes step S33c), and if the pulse width of the information is the third pulse width, executes step S33d).

[0032] S33c) Assign the arrival time of the current pulse signal information to the center point pulse i , increment the value of i by 1 and execute step S33e);

[0033] S33d) Assign the first target time before the arrival time of the current pulse signal information and the second target time after the arrival time to the center point pulse respectively i and pulse i+1 , increment the value of i by 2 and execute step S33e);

[0034] S33e) If the center point pulse i The value is smaller than the corresponding comparison benchmark point ben i , set the corresponding element in the decoded bitstream bitstream_S to the first value, if the center point pulse i The value is greater than the corresponding comparison benchmark point ben i , set the corresponding element in the decoded bitstream bitstream_S to the second value, and return to step S33b) until the pulse signal is obtained.

[0035] The present invention also provides a dual-mode secondary radar response signal decoding system, comprising:

[0036] a pulse classification unit configured to obtain information about a pulse signal, and if the pulse width of the information is the first pulse width, send the information about the pulse signal to a MarkX response signal decoding unit; and if the pulse width of the information is the second pulse width, send the information about the pulse signal to an S-mode response signal decoding unit;

[0037] The MarkX response signal decoding unit is used to cache the information of the pulse signal and perform MarkX response signal frame calculation and judgment. If the judgment is successful, the information of each pulse signal in the MarkX response signal is obtained according to the judgment result, and the MarkX response signal is decoded according to the information of each pulse signal to obtain a decoded bit stream of the MarkX response signal;

[0038] The S-mode response signal decoding unit is used to cache the information of the pulse signal and perform S-mode response signal frame calculation and judgment. If the judgment is passed, it continues to obtain the information of the pulse signal to perform S-mode response signal decoding to obtain the decoded bit stream of the S-mode response signal.

[0039] Compared with the prior art, the advantages of the present invention are:

[0040] The present invention adopts two different decoding methods based on the structural characteristics of the unfair mode response signals, which can quickly decode the information of the multi-mode secondary radar response signals. In addition, the present invention adopts a pipeline processing method for decoding the two types of secondary radar response signals, which can achieve real-time processing of the decoding results. Therefore, to a certain extent, the processing capability and efficiency of the multi-mode secondary radar response signals are improved, and the adaptability to the airspace environment with high-density response signals is also improved, reducing false alarms and missed detections. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the MarkX response signal structure diagram.

[0042] Figure 2 This is the structure diagram of the S-mode response signal.

[0043] Figure 3 This is a flow chart of the method according to the first embodiment of the present invention.

[0044] Figure 4 Schematic diagram of caching pulse signal information with a pulse width of 0.45 us in step S2) of the first embodiment of the present invention.

[0045] Figure 5 Schematic diagram of decoding the S-mode response signal according to an embodiment of the present invention.

[0046] Figure 6 Schematic diagram of caching pulse signal information with a pulse width of 0.5 us in step S3) of the first embodiment of the present invention.

[0047] Figure 7 This is a flowchart of decoding the S-mode response signal in step S3) of the first embodiment of the present invention.

[0048] Figure 8 This is the actual MarkX response signal of the first embodiment of the present invention.

[0049] Figure 9 This is the S-mode response signal used in the first embodiment of the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0051] The modes of secondary radar response signals include A / C mode and S mode, such as Figure 1As shown in the figure, in the MarkX response signal of A / C mode, F1 and F2 are frame pulses, and SPI is the special position identification code pulse. The timing of these three pulses is fixed at 0, 20.3, and 24.65us. The 12 codes between the two frame pulses can be encoded into 2^12=4096 independent response codes. The time interval between adjacent information pulses is 1.45us, and the pulse width is 0.45us. Figure 2 As shown in Figure 1, the Mode S reply signal consists of a header and a reply data block. The four pulses in the header are preamble pulses with pulse timings of 0, 1, 3.5, and 4.5 µs, each with a pulse width of 0.5 µs. The reply data is contained in the reply data block and encoded using pulse position modulation. Each 1 µs period is divided into two 0.5 µs cycles. The last 24 bits are used for address parity check.

[0052] It can be seen that there is a significant difference in the pulse width of the MarkX reply signal and the S-mode reply signal. At the same time, after the pulse information is extracted, the obtained pulse signal information will contain the pulse width, arrival time and pulse amplitude of the pulse signal. Therefore, the mode type of the received secondary radar reply signal can be distinguished based on the pulse width in the detected pulse signal information, and corresponding decoding can be performed.

[0053] Example 1

[0054] Based on the above ideas, this embodiment proposes a decoding method for a dual-mode secondary radar response signal, such as Figure 3 As shown, the following steps are included:

[0055] S1) obtaining information of a pulse signal; if the pulse width of the information is the first pulse width (i.e., 0.45 μs), executing step S2); if the pulse width of the information is the second pulse width (i.e., 0.5 μs), executing step S3);

[0056] S2) Buffering the pulse signal information, performing MarkX response signal frame calculation and discrimination, if the discrimination passes, obtaining information of each pulse signal in the MarkX response signal based on the discrimination result, decoding the MarkX response signal based on the information of each pulse signal, obtaining a decoded bit stream of the MarkX response signal, and returning to step S1) until the end;

[0057] S3) Buffering the pulse signal information, performing S-mode response signal frame calculation and judgment, if the judgment is passed, continuing to obtain the pulse signal information to perform S-mode response signal decoding to obtain a decoded bit stream of the S-mode response signal.

[0058] Through the above steps, this embodiment distinguishes different modes of the secondary radar response signal according to the pulse width in the pulse signal information, and performs corresponding decoding for different modes, thereby meeting the requirements of multi-mode secondary radar signal decoding.

[0059] Before step S1) of this embodiment, the step of obtaining pulse signal information is also included, that is, the pulse signal is sequentially subjected to pulse signal detection and pulse information extraction to obtain pulse signal information. For pulse signal detection and pulse information extraction, this embodiment adopts the pulse signal detection and pulse information extraction method in patent publication number CN112766064A, and sequentially eliminates non-secondary radar response signals, performs coarse pulse width detection and fine pulse width detection, and thus obtains accurate pulse width and pulse center point. In this embodiment, the arrival time in the pulse signal information is selected as the time corresponding to the pulse center point; thereby, accurate pulse signal information including pulse width, arrival time and pulse amplitude is obtained.

[0060] According to the structure of the MarkX response signal, since a set of MarkX response signals contains a maximum of 15 pulse signals, this embodiment opens a first buffer area that can cache 15 pulse signal information with a pulse width of 0.45us, and stores the pulse signal information of the first buffer area in positions with indexes from 0 to 14. In the initial state, the pulse signal information data value in the positions with indexes from 0 to 14 in the first buffer area is 0, indicating that there is no pulse signal information. Figure 4 As shown, when a new pulse signal information with a pulse width of 0.45us is detected, the pulse signal information at the position indexed at 0 in the interval is released, and the indexes corresponding to the remaining pulse signal information are moved forward one position in sequence, that is, the positions previously indexed at 1 to 14 are updated to the positions indexed at 0 to 13, and the position previously indexed at 0 is updated to the position indexed at 14, and finally the new pulse signal information is stored at the position indexed at 14, thereby ensuring that the latest 15 pulse signal information with a pulse width of 0.45us are always cached. Based on this configuration, the specific steps of caching the pulse signal information in step S2) include:

[0061] S21) In order to update the originally cached pulse signal information to the latest pulse signal information, first release the pulse signal information at the head position of the first cache index, that is, the pulse signal information at the position with index 0, advance the indexes of the remaining pulse signal information in the first cache by one position, and save the current pulse signal information at the tail position of the first cache index, that is, save it at the position with index 14, and finally execute the step of calculating and judging the MarkX response signal frame.

[0062] In this embodiment, the steps of calculating and determining the MarkX response signal frame in step S2) specifically include:

[0063] S22a) Select the pulse signal pulse45 of the first buffer index target position m The information is used to calculate the pulse signal pulse45 mThe information and the pulse signals pulse45 before the index target position in the first buffer area index The difference in arrival time TOAD in the information index ;

[0064] In this embodiment, considering that the position with index 14 can cache SPI pulse signal information, the first buffer index target position is the position with index 13, so m is 13, pulse45 index It is the pulse signal corresponding to the position of the first buffer index from 0 to 12. Therefore, index is any value from 0 to 12. According to the above content, if the number of cached pulse signals is less than 15, there may be no cached pulse signal information in the first buffer index target position and the position before the index target position. In this case, the corresponding pulse signal pulse45 m or pulse45 index The arrival time in the information is 0;

[0065] S22b) If there is a difference value TOAD within the preset first interval index , then the corresponding pulse signal pulse45 index and pulse signal pulse45 m The frame pulse of the MarkX response signal, pulse signal pulse45 index Information and pulse signal pulse45 m The information between each pulse signal pulse45 k The information is the pulse signal information between the frame pulses in the MarkX response signal. If the difference TOAD index If both are outside the preset first interval, return to step S1).

[0066] In this embodiment, the first interval is [20.3-error, 20.3+error], where error is the error and has a value of 0.1. index Meet 20.3-error≤TOAD index When ≤20.3+error, a set of MarkX response signal frames is detected, and the pulse signal pulse45 m and pulse45 index They are the frame pulses of the MarkX response signal of this group, and the pulse signals pulse45 between the frame pulses k The information can be used for subsequent decoding process.

[0067] In step S2 of this embodiment, the specific steps of decoding the MarkX response signal according to the information of each pulse signal include:

[0068] S23a) Calculate each pulse signal pulse45 respectively k Information and pulse signal pulse45 index The difference in arrival time in the information is obtained, and the difference is divided by the first preset value to obtain the calculation result dist corresponding to each pulse signal. The expression is as follows:

[0069] dist=(pulse45 k -pulse45 index ) / 1.45 (1)

[0070] In the above formula, pulse45 index is the arrival time of the frame pulse obtained in step S22b), pulse45 k is the arrival time of each pulse signal between the frame pulses in step S22b);

[0071] S23b) rounding off the calculated result dist to an integer and then subtracting 1 to obtain each pulse signal pulse45 k The position in the MarkX response signal is expressed as follows:

[0072] true_index=round(dist)-1 (2)

[0073] In the above formula, round() means rounding off decimals to integers, and subtracting 1 is to take into account that the index of the corresponding element in the decoded bit stream of each pulse in the MarkX response signal starts from 0;

[0074] Initialize the decoded bitstream bitstream_Mark according to the information of the MarkX response signal, and Figure 1 , a group of pulses of MarkX response signal includes [C1 A1 C2 A2 C4 A4 X B1 D1 B2 D2 B4 D4 SPI], so the decoded bit stream bitstream_Mark = [0 0 0 0 0 0 0 0 0 0 0 0 0], in which the elements correspond one to one to all the pulses in a group of MarkX response signal. According to formula (2), the pulse signal pulse45 k The corresponding element in the decoded bitstream bitstream_Mark is set to the target value, expressed as:

[0075] bitstream_Mark(true_index)=1 (3)

[0076] The pulse signal pulse45 in the bitstream bitstream_Mark is about to be decoded k The corresponding element is set to 1;

[0077] S23c) Calculate the pulse signal pulse45 at the tail position of the first buffer index n Information and pulse signal pulse45 m The difference in arrival time TOAD in the information SPI , if the difference TOAD SPI In a preset second interval, the corresponding element of the SPI pulse of the MarkX response signal in the decoded bitstream bitstream_Mark is set to a target value.

[0078] In this embodiment, m is 13 and n is 14, TOAD SPI The second interval is [4.35-error, 4.35+error], where error is the error and takes the value of 0.1. SPI Meet 4.35-error≤TOAD SPI When ≤4.35+error, the element with index 13 in the decoded bitstream bitstream_Mark, that is, the element corresponding to the SPI pulse, is set to 1.

[0079] Through the above steps, the complete decoding result of the MarkX reply signal can be obtained. The entire process adopts the pipeline processing method, which can achieve real-time processing of the decoding results, thereby improving the processing capability and efficiency of multi-mode secondary radar reply signals, and also improving the adaptability to the airspace environment of high-density reply signals, avoiding false alarms and missed detections.

[0080] Based on the structure of S-mode reply signal, such as Figure 5 As shown, a set of S-mode response signals includes a leading pulse consisting of 4 pulses and 56 or 112 response data blocks thereafter. Therefore, in this embodiment, a second buffer area capable of caching 4 pulse signal information with a pulse width of 0.5us is opened for the leading pulse of the S-mode response signal, and the pulse signal information of the second buffer area is stored in positions indexed from 0 to 3. In the initial state, the information data value of the pulse signal in the positions indexed from 0 to 3 in the second buffer area is 0, indicating that there is no pulse signal information. Figure 6 As shown, its working principle is the same as that of the first buffer area, which will not be repeated here. Based on this configuration, the specific steps of caching the pulse signal information in step S3) include:

[0081] S31) In order to update the originally cached pulse signal information to the latest pulse signal information, first release the pulse signal information at the head position of the second cache index, that is, the pulse signal information at the position with index 0, and advance the indexes corresponding to the remaining pulse signal information in the second cache by one position, and save the current pulse signal information at the tail position of the second cache index, that is, save it at the position with index 3, and finally execute the step of calculating and judging the S-mode response signal framework.

[0082] In this embodiment, the calculation and determination of the Mode S reply signal framework in step S3) specifically includes the following steps:

[0083] S32a) respectively calculating the arrival time differences between the information of the pulse signal at the index head position of the second buffer area and the information of each pulse signal at the index other positions, that is, respectively calculating the arrival time differences TOAD1, TOAD2 and TOAD3 between the information of the pulse signal at the position indexed by 0 in the second buffer area and the information of the pulse signals at the positions indexed by 1, 2 and 3;

[0084] According to the above description, if the number of cached pulse signals is less than 4, there may be no cached pulse signal information in the index head position and other index positions of the second buffer area. In this case, the arrival time in the corresponding pulse signal information is 0;

[0085] S32b) If the differences are all within the corresponding preset intervals, the pulse corresponding to the second buffer area is the leading pulse of the S-mode response signal, and the judgment is passed; otherwise, the process returns to step S1).

[0086] In this embodiment, for the difference TOAD1 between the arrival times of the pulse signals at the position with index 0 and the position with index 1 in the second cache area, the corresponding interval is set to [1.0-error, 1.0+error], where error is the error and the value is 0.1; for the difference TOAD2 between the arrival times of the pulse signals at the position with index 0 and the position with index 2 in the second cache area, the corresponding interval is set to [3.5-error, 3.5+error], where error is the error and the value is 0.1; for the difference TOAD3 between the arrival times of the pulse signals at the position with index 0 and the position with index 3 in the second cache area, the corresponding interval is set to [4.5-error, 4.5+error], where error is the error and the value is 0.1.

[0087] When TOAD1 satisfies 1.0-error≤TOAD1≤1.0+error, TOAD2 satisfies 3.5-error≤TOAD2≤3.5+error, and TOAD3 satisfies 4.5-error≤TOAD3≤4.5+error, the S-mode response signal has been detected and the pulse signal of its response data block will arrive after 3us.

[0088] For decoding of the S-mode reply signal, this embodiment adopts a method of comparing the pulse arrival time with a defined reference for decoding. First, a comparison reference point is defined. i Then continue to obtain the information of the pulse signal, and update the corresponding center point pulse according to the pulse width type and arrival time of the information i The value of the center point pulse i The corresponding comparison point ben i The comparison result of the values ​​of is used to obtain the value of each element in the decoded bit stream of the S-mode response signal.

[0089] like Figure 5 As shown, in this embodiment, the comparison reference point ben i With the center point pulse i One-to-one correspondence, according to the second buffer index head position, that is, the arrival time of the pulse signal information at the index 0 position, and the response data block length of the S mode response signal, each comparison reference point ben is calculated. i The value of the function expression is as follows:

[0090] ben i =pulse500+8.25+(i-1) (4)

[0091] In the above formula, i is the sequence number, 1≤i≤N, N is the response data block duration of the S-mode response signal, N is 56 or 112, and the unit is microseconds (us), and pulse500 is the arrival time in the information of the pulse signal at the index 0 position in the second buffer area.

[0092] like Figure 7 As shown, in the S-mode response signal, the pulse signal of the response data block also undergoes pulse signal detection and pulse information extraction, and its pulse width includes two types: 0.5us and 1us. The pulse signal with a pulse width of 0.5us has a single corresponding center point, and the pulse signal with a pulse width of 1us has two corresponding center points. Based on these characteristics, this embodiment continues to obtain pulse signal information, and updates the corresponding center point pulse according to the pulse width type and arrival time of the information. i The value of the center point pulse i The corresponding comparison point beni The step of obtaining the value of each element in the decoded bit stream of the Mode S response signal based on the comparison result of the values ​​of

[0093] S33a) Initialize the decoded bitstream bitstream_S of the S-mode response signal according to the response information of the S-mode response signal. In this embodiment, the elements in the decoded bitstream bitstream_S are [bit0 bit1 ... bit N-2 bit N-1 ], where N is the duration of the response data block of the S-mode response signal, and its value is 56 or 112;

[0094] S33b) obtains information of the current pulse signal, and performs pulse width determination based on the information. If the pulse width of the information is the second pulse width (i.e., the pulse width is 0.5us), execute step S33c); if the pulse width of the information is the third pulse width (i.e., the pulse width is 1us), execute step S33d).

[0095] S33c) Assign the arrival time of the current pulse signal information to the center point pulse i , increment the value of i by 1 and execute step S33e);

[0096] S33d) Assign the first target time before the arrival time of the current pulse signal information and the second target time after the arrival time to the center point pulse respectively i and pulse i+1 , increment the value of i by 2 and execute step S33e);

[0097] In this embodiment, the first target time is 0.25us before the arrival time of the current pulse signal information, and the second target time is 0.25us after the arrival time of the current pulse signal information;

[0098] S33e) If the center point pulse i The value is smaller than the corresponding comparison benchmark point ben i , set the corresponding element in the decoded bitstream bitstream_S to the first value, if the center point pulse i The value is greater than the corresponding comparison benchmark point ben i , set the corresponding element in the decoded bitstream bitstream_S to the second value, and the value of the element in the decoded bitstream bitstream_S is the same as the center point pulse i The value and comparison benchmark ben i The relationship is as follows:

[0099]

[0100] That is, the center point pulse i The value is smaller than the corresponding comparison benchmark point ben i When the decoded bitstream bitstream_S corresponding element is set to 1, the center point pulse i The value is greater than or equal to the corresponding comparison benchmark point ben i When , the corresponding element of the decoded bitstream bitstream_S is set to 0;

[0101] Return to step S33b) until the pulse signal is acquired.

[0102] Through the above steps, when the S-mode reply signal is received, the decoding of the S-mode reply signal is also completed immediately, so that the decoding result is generated in real time, thereby improving the processing capability and efficiency of the multi-mode secondary radar reply signal, and also improving the adaptability to the airspace environment with high-density reply signals, avoiding false alarms and missed detections.

[0103] According to the method of this embodiment, for Figure 8 The decoding result of the MarkX response signal in the secondary radar response signal is: bitstream_Mark=[0 0 1 1 0 1 0 1 0 1 0 0 1 0];

[0104] According to the method of this embodiment, for Figure 9 The decoding result of the S-mode reply signal in the secondary radar reply signal is shown as follows:

[0105] Therefore, the method of this embodiment can quickly and accurately obtain decoding information of secondary radar response signals in different modes.

[0106] Example 2

[0107] According to the method of embodiment 1, this embodiment provides a decoding system for a dual-mode secondary radar response signal, including:

[0108] a pulse classification unit configured to obtain information about a pulse signal, and if the pulse width of the information is the first pulse width, send the information about the pulse signal to a MarkX response signal decoding unit; and if the pulse width of the information is the second pulse width, send the information about the pulse signal to an S-mode response signal decoding unit;

[0109] The MarkX response signal decoding unit is used to cache the information of the pulse signal and perform MarkX response signal frame calculation and judgment. If the judgment is successful, the information of each pulse signal in the MarkX response signal is obtained according to the judgment result, and the MarkX response signal is decoded according to the information of each pulse signal to obtain a decoded bit stream of the MarkX response signal;

[0110] The S-mode response signal decoding unit is used to cache the information of the pulse signal and perform S-mode response signal frame calculation and judgment. If the judgment is passed, it continues to obtain the information of the pulse signal to perform S-mode response signal decoding to obtain the decoded bit stream of the S-mode response signal.

[0111] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed above with reference to the preferred embodiment, it is not intended to limit the present invention. Therefore, any simple modifications, equivalent variations, and modifications to the above embodiment that do not depart from the technical solution of the present invention and are based on the technical essence of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for decoding a dual-mode secondary radar response signal, characterized in that: The following steps are involved: S1) obtaining information of a pulse signal; if the pulse width of the information is the first pulse width, executing step S2); if the pulse width of the information is the second pulse width, executing step S3); S2) Buffering the pulse signal information, performing MarkX response signal frame calculation and discrimination, if the discrimination passes, obtaining information of each pulse signal in the MarkX response signal based on the discrimination result, decoding the MarkX response signal based on the information of each pulse signal, obtaining a decoded bit stream of the MarkX response signal, and returning to step S1) until the end; S3) Cache the pulse signal information and perform S-mode reply signal frame calculation and judgment. If the judgment is passed, the arrival time of the pulse signal information at the index head position of the second buffer area and the response data block length of the S-mode reply signal are calculated to obtain the center points. Corresponding comparison benchmark , the function expression is as follows: In the above formula, is the sequence number, 1≤i≤N, N is the response data block duration of the S-mode response signal, The arrival time of the pulse signal information of the second buffer index head position; Then continue to obtain the information of the pulse signal, and update the corresponding center point according to the pulse width type and arrival time of the information The value of the center point Compare with the corresponding benchmark point The comparison result of the values ​​of and is used to obtain the values ​​of each element in the decoded bit stream of the S-mode response signal, including: S33a) Initialize the decoded bit stream of the S-mode response signal according to the response information of the S-mode response signal ; S33b) Obtain information about the current pulse signal. If the pulse width of the information is the second pulse width, execute step S33c). If the pulse width of the information is the third pulse width, execute step S33d). S33c) Assign the arrival time of the current pulse signal information to the center point , increment the value of i by 1 and execute step S33e); S33d) Assign the first target time before the arrival time of the current pulse signal information and the second target time after the arrival time to the center point respectively and , increment the value of i by 2 and execute step S33e); S33e) If the center point The value is less than the corresponding comparison benchmark point , the decoded bitstream The corresponding element in is set to the first value. If the center point The value is greater than the corresponding comparison benchmark point , the decoded bitstream The corresponding element in is set to the second value, and the process returns to step S33b) until the pulse signal is acquired.

2. The method for decoding a dual-mode secondary radar response signal according to claim 1, wherein: The specific steps of caching the pulse signal information in step S2) include: releasing the pulse signal information at the head position of the first buffer area index, advancing the indexes corresponding to the remaining pulse signal information in the first buffer area by one position, saving the current pulse signal information at the tail position of the first buffer area index, and executing the steps of calculating and judging the MarkX response signal framework.

3. The method for decoding a dual-mode secondary radar response signal according to claim 2, wherein: The steps of calculating and judging the MarkX response signal frame in step S2) specifically include: S22a) Select the pulse signal of the first buffer index target position information, and calculate the pulse signal The information and the pulse signals before the index target position in the first buffer area The difference in arrival time in the information ; S22b) If there is a difference within the preset first interval , then the corresponding pulse signal and pulse signals Frame pulse of MarkX response signal, pulse signal Information and pulse signals The pulse signals between the information The information is the pulse signal information between the frame pulses in the MarkX response signal. If the difference are all outside the preset first interval, return to step S1).

4. The method for decoding a dual-mode secondary radar response signal according to claim 3, wherein: In step S2), the specific steps of decoding the MarkX response signal according to the information of each pulse signal include: S23a) Calculate each pulse signal separately Information and pulse signals The difference in arrival time in the information is obtained, and the difference is divided by the first preset value to obtain the calculation result corresponding to each pulse signal. ; S23b) Calculation results Round off and subtract 1 to get each pulse signal The position in the MarkX response signal, initialize the decoded bit stream according to the information of the MarkX response signal , the pulse signal When decoding the bitstream The corresponding elements in are set to the target values; S23c) Calculate the pulse signal of the tail position of the first buffer index Information and pulse signals The difference in arrival time in the information , if the difference In the preset second interval, the SPI pulse of the MarkX response signal is decoded in the bit stream The corresponding element in is set to the target value.

5. The method for decoding a dual-mode secondary radar response signal according to claim 1, wherein: The specific steps of caching the pulse signal information in step S3) include: Release the information of the pulse signal at the head position of the second buffer index, advance the indexes corresponding to the remaining pulse signal information in the second buffer by one position, save the information of the current pulse signal at the tail position of the second buffer index, and execute the steps of calculating and judging the S-mode response signal framework.

6. The method for decoding a dual-mode secondary radar response signal according to claim 5, characterized in that: The calculation and identification of the Mode S reply signal framework in step S3) specifically includes the following steps: S32a) respectively calculating the arrival time differences between the information of the pulse signal at the index head position of the second buffer area and the information of each pulse signal at the index other positions; S32b) If the differences are all within the corresponding preset intervals, the pulse corresponding to the second buffer area is the leading pulse of the S-mode response signal, and the determination is successful; otherwise, the process returns to step S1).

7. A decoding system for a dual-mode secondary radar response signal, characterized in that: include: a pulse classification unit configured to obtain information about a pulse signal, and if the pulse width of the information is the first pulse width, send the information about the pulse signal to a MarkX response signal decoding unit; and if the pulse width of the information is the second pulse width, send the information about the pulse signal to an S-mode response signal decoding unit; The MarkX response signal decoding unit is used to cache the information of the pulse signal and perform MarkX response signal frame calculation and judgment. If the judgment is successful, the information of each pulse signal in the MarkX response signal is obtained according to the judgment result, and the MarkX response signal is decoded according to the information of each pulse signal to obtain a decoded bit stream of the MarkX response signal; The S-mode response signal decoding unit is used to cache the information of the pulse signal and perform S-mode response signal frame calculation and judgment. If the judgment is passed, the arrival time of the pulse signal information at the index head position of the second buffer area and the response data block length of the S-mode response signal are calculated to obtain the center points. Corresponding comparison benchmark , the function expression is as follows: In the above formula, is the sequence number, 1≤i≤N, N is the response data block duration of the S-mode response signal, The arrival time of the pulse signal information of the second buffer index head position; Then continue to obtain the information of the pulse signal, and update the corresponding center point according to the pulse width type and arrival time of the information The value of the center point Compare with the corresponding benchmark point The comparison result of the values ​​of and is used to obtain the values ​​of each element in the decoded bit stream of the S-mode response signal, including: S33a) Initialize the decoded bit stream of the S-mode response signal according to the response information of the S-mode response signal ; S33b) Obtain information about the current pulse signal. If the pulse width of the information is the second pulse width, execute step S33c). If the pulse width of the information is the third pulse width, execute step S33d). S33c) Assign the arrival time of the current pulse signal information to the center point , increment the value of i by 1 and execute step S33e); S33d) Assign the first target time before the arrival time of the current pulse signal information and the second target time after the arrival time to the center point respectively and , increment the value of i by 2 and execute step S33e); S33e) If the center point The value is less than the corresponding comparison benchmark point , the decoded bitstream The corresponding element in is set to the first value. If the center point The value is greater than the corresponding comparison benchmark point , the decoded bitstream The corresponding element in is set to the second value, and the process returns to step S33b) until the pulse signal is acquired.

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