A method for transmitting and adaptively capturing burst frames in non-cooperative spread spectrum

Abstract

The invention discloses a method for sending and adaptively quickly capturing a non-cooperative spread spectrum burst frame, and relates to the field of satellite communication. The spread spectrum burst frame structure design in the invention adopts a non-cooperative design of a burst header preamble sequence and a data payload to realize the rapid capture of the spread spectrum burst, and is easy to demodulate the resource optimization design of synchronous processing; the spread spectrum preamble sequence is constructed based on Gray complementary code to realize the burst spread spectrum function, the constructed preamble sequence is short and has good autocorrelation and cross-correlation characteristics, and can realize high reliability reception of burst spread spectrum under low signal-to-noise ratio; the shorter spread spectrum burst design can ensure high transmission efficiency; based on the spread spectrum burst frame structure, the receiving end adopts a constant false alarm capture algorithm to realize automatic and rapid matching of the burst spread spectrum ratio.

Description

Technical Field

[0001] The invention relates to the field of satellite communication, and in particular to a method for sending and adaptively quickly capturing a non-cooperative spread spectrum burst frame. Background Art

[0002] In recent years, with the development of satellite communication technology and its widespread application in complex and multi-scenario scenarios, there is a clear demand for the spread spectrum technology of burst signals. On the one hand, burst spread spectrum can be used to reduce the spectral density of burst signals to reduce the possibility of interference from neighboring satellites or improve the concealment of burst signals. However, due to different antenna apertures, different spread spectrum ratios need to be selected for each station to send bursts to achieve the same effect. If the same system requires the same receiving end to receive signals with different spread spectrum ratios at the same time, the traditional pre-configuration method will bring a lot of trouble to the networking application; on the other hand, the receiving remote station using spread spectrum must ensure normal operation at a lower signal-to-noise ratio, and the burst preamble sequence length will increase with the increase of the spread spectrum ratio, which will lead to an increase in the complexity of digital signal processing. Summary of the invention

[0003] In view of this, the present invention proposes a method for sending and adaptively capturing non-cooperative spread spectrum burst frames. The frame structure designed by the method is shorter and has better autocorrelation and cross-correlation characteristics, which can achieve high reliability reception of burst spread spectrum under low signal-to-noise ratio, ensure high transmission efficiency, and facilitate resource optimization design for demodulation and synchronization processing; based on the spread spectrum burst frame structure, the constant false alarm capture algorithm can be used to achieve automatic and rapid matching of the burst spread spectrum ratio.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A method for sending a non-cooperative spread spectrum burst frame, applied to a sending end of a burst spread spectrum system, comprises the following steps:

[0006] Extracting coding modulation mode and spreading ratio information according to configuration parameters;

[0007] Perform CRC check, scrambling, and LDPC encoding on the data to be sent;

[0008] Perform burst framing of a spread spectrum preamble sequence corresponding to the spread spectrum ratio and the LDPC-coded data to be transmitted to obtain a spread spectrum burst frame;

[0009] Performing constellation mapping on the spread spectrum burst frame after framing;

[0010] Spreading the constellation-mapped spread spectrum burst frame according to the spreading ratio information;

[0011] Perform shaping filtering on the spread spectrum burst frame after spread spectrum, output modulated baseband data, and send the modulated baseband data out;

[0012] The spread spectrum preamble sequence corresponding to the spreading ratio and the LDPC-coded data to be sent are burst framed to obtain a spread spectrum burst frame, as follows:

[0013] Step S1, using the basic sequence linear combination method to generate the unspread preamble sequence M, the length of the unspread preamble sequence M is recorded as 2 , the leading sequence M before the unspread The bit data is recorded as A, and then The bit data is denoted as B;

[0014] Step S2, spreading the unspread preamble sequence M according to the spreading ratio s to obtain a preliminary spread preamble sequence, and +1 to Bit data is recorded as , k=1,2,3,……,s; ;

[0015] Step S3, according to Construct Gray complementary code matrix with spreading ratio s , The length is bit, t=1,2,3,…,2s;

[0016] Step S4, construct the final spread spectrum preamble sequence:

[0017] in, Before The bit data is: ;

[0018] After The bit data is: ;

[0019] in, represents XOR, completing the generation of the spread spectrum preamble sequence;

[0020] Step S5, spreading the data symbol according to the spreading ratio s and performing an XOR operation with the pseudo-random data to obtain a data payload, wherein different spreading ratios correspond to data of different lengths in the same pseudo-random sequence;

[0021] Step S6, splicing the tail of the spread spectrum preamble sequence and the head of the data payload to complete the burst framing of the spread spectrum preamble sequence and data corresponding to the spreading ratio.

[0022] An adaptive fast acquisition method for non-cooperative spread spectrum burst frames, applied to a receiving end of a burst spread spectrum system, for receiving data sent by the above method, comprises the following steps:

[0023] Step S1: Generate corresponding spread spectrum preamble sequence for the spread spectrum ratio information of all transmitting ends ; And set corresponding preset thresholds for different spreading ratios;

[0024] Step S2, receiving a spread spectrum burst frame, capturing a spread spectrum preamble sequence in the spread spectrum burst frame according to the control type, and storing the captured data in a shift register;

[0025] Step S3, setting a variable q indicating a spreading ratio, and setting q=1;

[0026] Step S4, calculate and The value of is the spread spectrum preamble sequence with a spreading ratio of q The pth bit data of is the p-th bit data of the spread spectrum pilot sequence captured by the receiving end. The superscript * indicates conjugation. Half the data length of the unspread preamble sequence;

[0027] If the spread spectrum preamble sequence No.2 +1 to Bit data and spread spectrum preamble sequence 1st to 2nd If the bit data is consistent, = ①, otherwise =- ②;

[0028] If the spread spectrum preamble sequence No. +1 to Bit data and spread spectrum preamble sequence No. +1 to 2nd If the bit data is consistent, = ③ Otherwise =- ④, =1,2,3,......,q;

[0029] According to formula ①②③④, Bit data is the basic unit, calculation The correlation value between the received preamble sequence and the , N=2 q;

[0030] Step S5, calculating the power value of the spread spectrum preamble sequence captured by the receiving end , and calculate the discriminant value ;

[0031] Step S6, if u is greater than the preset threshold corresponding to the spreading ratio of 1, execute step S8, otherwise execute step S7;

[0032] Step S7, capturing the spread spectrum preamble sequence in the spread spectrum burst frame according to the data type, storing the captured data in the shift register, and executing steps S4 to S5 to obtain a new u value. If u is greater than a preset threshold corresponding to a spread spectrum ratio of 1, executing step S8, otherwise executing step S2;

[0033] Step S8, determine q= +1 whether it is true, is the maximum spreading ratio in each transmitter, if q= +1 is established, then execute step S2; if q= +1 is not true, then let q=q+1, execute steps S4 to S5 to obtain a new u value. If u is greater than the preset threshold corresponding to the spreading ratio q, continue to execute step S8. If u is not greater than the preset threshold corresponding to the spreading ratio q, then the spreading ratio of the currently received spread spectrum burst frame is recorded as q-1, the spread spectrum burst frame is despread, and the adaptive fast capture of the non-cooperative spread spectrum burst frame is completed.

[0034] Furthermore, in step S1, a corresponding spread spectrum preamble sequence is generated for the spread spectrum ratio information of all transmitting ends. ; The details are as follows:

[0035] Step S101, using the basic sequence linear combination method to generate an unspread preamble sequence M, the length of the unspread preamble sequence M is recorded as 2 , the leading sequence M before the unspread The bit data is recorded as A, and then The bit data is denoted as B;

[0036] Step S102: Spread the unspread preamble sequence M according to the spreading ratio s to obtain a preliminary spread preamble sequence , the initial spread spectrum preamble sequence No.2 +1 to Bit data is recorded as , k=1,2,3,……,s; ;

[0037] Step S103, according to Construct Gray complementary code matrix with spreading ratio s , The length is bit, t=1,2,3,…,2s;

[0038] Step S104: construct the final spread spectrum preamble sequence :

[0039] in, Before The bit data is: ;

[0040] After The bit data is: ;

[0041] in, It represents exclusive OR, completing the generation of the spread spectrum preamble sequence corresponding to the spreading ratio s.

[0042] Due to the adoption of the above technical solution, the beneficial effects of the present invention compared with the prior art are:

[0043] 1. The present invention realizes burst spread spectrum function by constructing a spread spectrum preamble sequence based on Gray complementary code. The construction method is easy to optimize resource design and reduce the demand for demodulation resources.

[0044] 2. The spread spectrum preamble sequence constructed by the present invention is relatively short and has good autocorrelation and cross-correlation characteristics, and can achieve high-reliability reception of burst spread spectrum under low signal-to-noise ratio.

[0045] 3. The spread spectrum burst preamble sequence and data payload in the present invention adopt non-cooperative different spread spectrum processing designs, which can adaptively and quickly match the burst spread spectrum ratio and type.

[0046] 4. The present invention is based on a design of a shorter spread spectrum preamble sequence and no pilot inserted into the data payload, which can ensure a higher transmission efficiency under a certain frame length. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The figure is a schematic diagram of the processing flow of the spread spectrum burst frame in an embodiment of the present invention.

[0048] Figure 2 It is a schematic diagram of the structure of a spread spectrum burst frame in an embodiment of the present invention.

[0049] Figure 3 The figure is a schematic diagram of a process of generating a spread spectrum preamble sequence in an embodiment of the present invention.

[0050] Figure 4 The figure is a schematic diagram of a process of quickly matching burst spreading ratio and type in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0052] A method for sending a non-cooperative spread spectrum burst frame, applied to a sending end of a burst spread spectrum system, comprises the following steps:

[0053] Extracting coding modulation mode and spreading ratio information according to configuration parameters;

[0054] Perform CRC check, scrambling, and LDPC encoding on the data to be sent;

[0055] Perform burst framing of a spread spectrum preamble sequence corresponding to the spread spectrum ratio and the LDPC-coded data to be transmitted to obtain a spread spectrum burst frame;

[0056] Performing constellation mapping on the spread spectrum burst frame after framing;

[0057] Spreading the constellation-mapped spread spectrum burst frame according to the spreading ratio information;

[0058] Perform shaping filtering on the spread spectrum burst frame after spread spectrum, output modulated baseband data, and send the modulated baseband data out;

[0059] The spread spectrum preamble sequence corresponding to the spreading ratio and the LDPC-coded data to be sent are burst framed to obtain a spread spectrum burst frame, as follows:

[0060] Step S1, using the basic sequence linear combination method to generate the unspread preamble sequence M, the length of the unspread preamble sequence M is recorded as 2 , the leading sequence M before the unspread The bit data is recorded as A, and then The bit data is denoted as B;

[0061] Step S2, spreading the unspread preamble sequence M according to the spreading ratio s to obtain a preliminary spread preamble sequence, and +1 to Bit data is recorded as , k=1,2,3,……,s; ;

[0062] Step S3, according to Construct Gray complementary code matrix with spreading ratio s , The length is bit, t=1,2,3,…,2s;

[0063] Step S4, construct the final spread spectrum preamble sequence:

[0064] in, Before The bit data is: ;

[0065] After The bit data is: ;

[0066] in, represents XOR, completing the generation of the spread spectrum preamble sequence;

[0067] Step S5, spreading the data symbol according to the spreading ratio s and performing an XOR operation with the pseudo-random data to obtain a data payload, wherein different spreading ratios correspond to data of different lengths in the same pseudo-random sequence;

[0068] Step S6, splicing the tail of the spread spectrum preamble sequence and the head of the data payload to complete the burst framing of the spread spectrum preamble sequence and data corresponding to the spreading ratio.

[0069] An adaptive fast acquisition method for non-cooperative spread spectrum burst frames, applied to a receiving end of a burst spread spectrum system, for receiving data sent by the above method, comprises the following steps:

[0070] Step S1: Generate corresponding spread spectrum preamble sequence for the spread spectrum ratio information of all transmitting ends ; And set corresponding preset thresholds for different spreading ratios;

[0071] Step S2, such as Figure 4 As shown, a spread spectrum burst frame is received, a spread spectrum preamble sequence in the spread spectrum burst frame is captured according to the control type, and the captured data is stored in a shift register;

[0072] Step S3, setting a variable q indicating a spreading ratio, and setting q=1;

[0073] Step S4, calculate and The value of is the spread spectrum preamble sequence with a spreading ratio of q The pth bit data of is the p-th bit data of the spread spectrum pilot sequence captured by the receiving end. The superscript * indicates conjugation. Half the data length of the unspread preamble sequence;

[0074] If the spread spectrum preamble sequence No.2 +1 to Bit data and spread spectrum preamble sequence 1st to 2nd If the bit data is consistent, = ①, otherwise =- ②;

[0075] If the spread spectrum preamble sequence No. +1 to Bit data and spread spectrum preamble sequence No. +1 to 2nd If the bit data is consistent, = ③ Otherwise =- ④, =1,2,3,......,q;

[0076] According to formula ①②③④, Bit data is the basic unit, calculation The correlation value between the received preamble sequence and the , N=2 q;

[0077] Step S5, calculating the power value of the spread spectrum preamble sequence captured by the receiving end , and calculate the discriminant value ;

[0078] Step S6, if u is greater than the preset threshold corresponding to the spreading ratio of 1, execute step S8, otherwise execute step S7;

[0079] Step S7, capturing the spread spectrum preamble sequence in the spread spectrum burst frame according to the data type, storing the captured data in the shift register, and executing steps S4 to S5 to obtain a new u value. If u is greater than a preset threshold corresponding to a spread spectrum ratio of 1, executing step S8, otherwise executing step S2;

[0080] Step S8, determine q= +1 whether it is true, is the maximum spreading ratio in each transmitter, if q= +1 is established, then execute step S2; if q= +1 is not true, then let q=q+1, execute steps S4 to S5 to obtain a new u value. If u is greater than the preset threshold corresponding to the spreading ratio q, continue to execute step S8. If u is not greater than the preset threshold corresponding to the spreading ratio q, then the spreading ratio of the currently received spread spectrum burst frame is recorded as q-1, the spread spectrum burst frame is despread, and the adaptive fast capture of the non-cooperative spread spectrum burst frame is completed.

[0081] Furthermore, in step S1, a corresponding spread spectrum preamble sequence is generated for the spread spectrum ratio information of all transmitting ends. ; The details are as follows:

[0082] Step S101, using the basic sequence linear combination method to generate an unspread preamble sequence M, the length of the unspread preamble sequence M is recorded as 2 , the leading sequence M before the unspread The bit data is recorded as A, and then The bit data is denoted as B;

[0083] Step S102: Spread the unspread preamble sequence M according to the spreading ratio s to obtain a preliminary spread preamble sequence , the initial spread spectrum preamble sequence No.2 +1 to Bit data is recorded as , k=1,2,3,……,s; ;

[0084] Step S103, according to Construct Gray complementary code matrix with spreading ratio s , The length is bit, t=1,2,3,…,2s;

[0085] Step S104: construct the final spread spectrum preamble sequence :

[0086] in, Before The bit data is: ;

[0087] After The bit data is: ;

[0088] in, It represents exclusive OR, completing the generation of the spread spectrum preamble sequence corresponding to the spreading ratio s.

[0089] Specifically, Figure 1 The invention designs a spread spectrum burst data processing flow. The transmitting end extracts the coding modulation mode and the spread spectrum ratio information according to the configuration parameters, the data is subjected to CRC, scrambling, and LDPC coding, the leading header and the data corresponding to different spread spectrum ratios are burst framed, and then the framed data is constellation mapped, and then the modulated data symbols are spread according to the spread spectrum ratio information, and finally the shaping filter outputs the modulated baseband data to complete the output of the burst spread spectrum data.

[0090] Figure 2 The invention designs a spread spectrum burst data frame structure, which is composed of a spread spectrum preamble sequence and a data payload.

[0091] The burst types are designed to be data and control types, and the preamble sequences of different types are different. In this embodiment, the modulation mode is BPSK and the symbol length is ( is the frequency spreading factor, The minimum basic length for constructing the preamble sequence). The spread spectrum preamble sequence mainly completes the functions of capturing spread spectrum burst data and assisting the TDMA system timing.

[0092] The data payload carries burst data and is composed of coded modulated symbols. In this embodiment, the modulation method is QPSK;

[0093] The preamble sequence should have good correlation characteristics to ensure capture performance, distinguish burst types and complete demodulation synchronization of spread spectrum signals. However, it is difficult to obtain the long preamble sequence after spread spectrum through direct search, and the capture of spread spectrum bursts is restricted by hardware platform resources. Using Gray complementary sequence, the new preamble sequence constructed according to the spread spectrum ratio and basic sequence can maintain the autocorrelation and cross-correlation characteristics of the sequence to a large extent. Figure 1 Based on the burst structure, a burst header spread spectrum preamble sequence method is constructed based on Gray complementary code. The spread spectrum preamble sequence is generated on the basis of the unspread spectrum preamble sequence. The unspread spectrum preamble sequence is generated by a linear combination of basic sequences. The spread spectrum of the spread spectrum burst preamble sequence is completed by inverting or repeating the spreading ratio.

[0094] Figure 3 The present invention designs a method for generating burst preamble sequences with different spreading ratios. The unspread burst preamble sequence M is defined as [ A B ] , the lengths of A and B are ,

[0095] Construct the final spread spectrum preamble sequence:

[0096] in, Before The bit data is: ,

[0097] After The bit data is: , represents XOR, k=1,2,3,…,s; ;

[0098] in is the spreading ratio, Gray complementary code matrix for All-0 or all-1 matrix of bits, t=1,2,3,…,2s; different spreading ratios corresponding to Gray coding generation method is satisfied. When the matrix value is "0", the XOR result is A or B. When the matrix value is "1", the XOR result is -A or -B. The final spread spectrum burst preamble sequence is obtained based on the spread spectrum ratio s. , , , , , , , ...... the cyclic form, the spread spectrum ratio burst preamble sequence conforms to the Gray complementary code format;

[0099] The data payload adopts direct sequence spread spectrum method, and different spreading ratios are generated by the same sequence. The spreading method is that each information bit is expanded to all "1" or all "0" of the corresponding spreading multiple, and then an XOR operation is performed with the spreading sequence to obtain the spread spectrum output.

[0100] The preamble sequence and data payload of the spread spectrum burst data adopt different spread spectrum processing methods. The preamble sequence of the spread spectrum can be pre-processed to complete the overall despreading of the preamble and data. This implementation structure can reduce FPGA resources.

[0101] Figure 4 The figure is a schematic diagram of the implementation flow of quickly matching burst spreading ratio and type in an embodiment of the present invention.

[0102] The detection algorithm based on constant false alarm probability has high detection accuracy. The threshold setting is independent of the noise intensity and the signal receiving level. The detection threshold expression is:

[0103]

[0104] The detection algorithm of constant false alarm probability is used to capture the spread spectrum burst. The relevant calculation at the receiving end is used to realize the structure. Symbols are the smallest basic processing units, which are calculated separately Symbol-related values;

[0105] Each group of correlation results is combined according to the principle of the spread spectrum preamble sequence to generate the corresponding actual correlation result; logical judgment is made according to the preset threshold, power and correlation value;

[0106] Under the spread spectrum burst frame structure generated above, due to the use of The spread spectrum burst detection implementation structure of the symbol correlation calculation can be pre-processed in combination with the spread spectrum preamble sequence, thereby ensuring that the spread spectrum signals of different spreading ratios and burst types can further reduce the implementation resources of demodulation synchronization under the premise of low signal-to-noise ratio capture performance.

[0107] The burst header spread spectrum preamble sequence method based on Gray complementary code is generated on the basis of the unspread spectrum preamble sequence. At the same time, the preamble sequence and data payload of the spread spectrum burst adopt different non-cooperative spread spectrum processing methods, and the detection algorithm with constant false alarm probability is used. The relevant processing and power calculation of the receiving end are all based on The basic processing unit is used to capture the spread spectrum burst. Based on the above characteristics, the spread spectrum ratio is cyclically incremented and the burst preamble and data are processed in a non-cooperative manner. The burst preamble sequence and the spread spectrum ratio are automatically identified by quickly calculating the correlation values ​​of different spread spectrum ratios and comparing them with the corresponding pre-stored threshold values, and the burst data is adaptively despread according to the spread spectrum ratio. The processing steps are as follows:

[0108] (1) First, the burst header is captured according to the burst data type 1, where the burst data type 1 is the control type. Under the symbol clock, the data enters the shift register in sequence to be correlated and power calculated.

[0109] (2) Every After the data is stored, it is read out from the shift register in sequence and combined with the corresponding leading sequence. The length is the basic unit for correlation and power calculation, where the spreading ratio The corresponding calculation data lengths are .

[0110] (3) Calculate the ratio of the correlation value to the power, and compare it with the preset threshold value of different spreading ratios to determine whether the burst data is to be despread and output. If the calculated correlation value is less than the set threshold when the spreading ratio is 1, the capture decision process of burst type 2 is performed, where burst type 2 is the data type; otherwise, the correlation calculation and decision process of burst type 1 with a higher spreading ratio is continued.

[0111] (4) If the relevant calculated values ​​of burst data type 1 and burst data type 2 are both less than the set threshold, it is considered that there is no burst data output at this time, and the above steps are repeated to restart the capture of burst data types 1 and 2.

[0112] In summary, the frame structure designed by the present invention is shorter and has better autocorrelation and cross-correlation characteristics, which can achieve high-reliability reception of burst spread spectrum under low signal-to-noise ratio, ensure high transmission efficiency, and facilitate resource optimization design for demodulation and synchronization processing; based on the spread spectrum burst frame structure, the constant false alarm capture algorithm is used to achieve automatic and fast matching of the burst spread spectrum ratio.

[0113] Those skilled in the art will appreciate that the embodiments described are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to the embodiments described. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for sending a non-cooperative spread spectrum burst frame, applied to a transmitting end of a burst spread spectrum system, comprising the following steps: Extracting coding modulation mode and spreading ratio information according to configuration parameters; Perform CRC check, scrambling, and LDPC encoding on the data to be sent; Perform burst framing of a spread spectrum preamble sequence corresponding to the spread spectrum ratio and the LDPC-coded data to be transmitted to obtain a spread spectrum burst frame; Performing constellation mapping on the spread spectrum burst frame after framing; Spreading the constellation-mapped spread spectrum burst frame according to the spreading ratio information; Perform shaping filtering on the spread spectrum burst frame after spread spectrum, output modulated baseband data, and send the modulated baseband data out; It is characterized in that a spread spectrum preamble sequence corresponding to the spreading ratio and the LDPC-coded data to be transmitted are burst framed to obtain a spread spectrum burst frame, which is specifically as follows: Step S1, using the basic sequence linear combination method to generate the unspread preamble sequence M, the length of the unspread preamble sequence M is recorded as 2 , the leading sequence M before the unspread The bit data is recorded as A, and then The bit data is denoted as B; Step S2, spreading the unspread preamble sequence M according to the spreading ratio s to obtain a preliminary spread preamble sequence, and +1 to Bit data is recorded as , k=1,2,3,……,s; ; Step S3, according to Construct Gray complementary code matrix with spreading ratio s , The length is bit, t=1,2,3,…,2s; Step S4, construct the final spread spectrum preamble sequence: in, Before The bit data is: ; After The bit data is: ; in, represents XOR, completing the generation of the spread spectrum preamble sequence; Step S5, spreading the data symbol according to the spreading ratio s and performing an XOR operation with the pseudo-random data to obtain a data payload, wherein different spreading ratios correspond to data of different lengths in the same pseudo-random sequence; Step S6, splicing the tail of the spread spectrum preamble sequence and the head of the data payload to complete the burst framing of the spread spectrum preamble sequence and data corresponding to the spreading ratio.

2. An adaptive fast acquisition method for non-cooperative spread spectrum burst frames, characterized in that: A receiving end applied to a burst spread spectrum system, for receiving data sent by the method of claim 1, comprising the following steps: Step S1: Generate corresponding spread spectrum preamble sequence for the spread spectrum ratio information of all transmitting ends , specifically: Step S101, using the basic sequence linear combination method to generate an unspread preamble sequence M, the length of the unspread preamble sequence M is recorded as 2 , the leading sequence M before the unspread The bit data is recorded as A, and then The bit data is denoted as B; Step S102: Spread the unspread preamble sequence M according to the spreading ratio s to obtain a preliminary spread preamble sequence , the initial spread spectrum preamble sequence No.2 +1 to Bit data is recorded as , k=1,2,3,……,s; ; Step S103, according to Construct Gray complementary code matrix with spreading ratio s , The length is bit, t=1,2,3,…,2s; Step S104: construct the final spread spectrum preamble sequence : in, Before The bit data is: ; After The bit data is: ; in, represents XOR, completes the generation of the spread spectrum preamble sequence corresponding to the spread spectrum ratio s; and sets the corresponding preset threshold for different spread spectrum ratios; Step S2, receiving a spread spectrum burst frame, capturing a spread spectrum preamble sequence in the spread spectrum burst frame according to the control type, and storing the captured data in a shift register; Step S3, setting a variable q indicating a spreading ratio, and setting q=1; Step S4, calculate and The value of is the spread spectrum preamble sequence with a spreading ratio of q The pth bit data of is the p-th bit data of the spread spectrum pilot sequence captured by the receiving end. The superscript * indicates conjugation. Half the data length of the unspread preamble sequence; If the spread spectrum preamble sequence No.2 +1 to Bit data and spread spectrum preamble sequence 1st to 2nd If the bit data is consistent, = ,otherwise =- ; If the spread spectrum preamble sequence No. +1 to Bit data and spread spectrum preamble sequence No. +1 to 2nd If the bit data is consistent, = ,otherwise =- , =1,2,3,......,q; According to the above formula, Bit data is the basic unit, calculation The correlation value between the received preamble sequence and the , N=2 q; Step S5, calculating the power value of the spread spectrum preamble sequence captured by the receiving end , and calculate the discriminant value ; Step S6, if u is greater than the preset threshold corresponding to the spreading ratio of 1, execute step S8, otherwise execute step S7; Step S7, capturing the spread spectrum preamble sequence in the spread spectrum burst frame according to the data type, storing the captured data in the shift register, and executing steps S4 to S5 to obtain a new u value. If u is greater than a preset threshold corresponding to a spread spectrum ratio of 1, executing step S8, otherwise executing step S2; Step S8, determine q= +1 whether it is true, is the maximum spreading ratio in each transmitter, if q= +1 is established, then execute step S2; if q= +1 is not true, then let q=q+1, execute steps S4 to S5 to obtain a new u value. If u is greater than the preset threshold corresponding to the spreading ratio q, continue to execute step S8. If u is not greater than the preset threshold corresponding to the spreading ratio q, then the spreading ratio of the currently received spread spectrum burst frame is recorded as q-1, the spread spectrum burst frame is despread, and the adaptive fast capture of the non-cooperative spread spectrum burst frame is completed.

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