Multi-system intra-pulse linear frequency modulation communication method

Abstract

The invention discloses a multi-system intra-pulse linear frequency modulation communication method, which is applied to a sending end and comprises the following steps: receiving a sent bit stream, and performing bit mapping on the bit stream to convert the bit stream into a symbol word; generating an embedded chirp signal according to the symbol word, and embedding the embedded chirp signal into frame data of a pre-generated mother chirp signal to generate a baseband signal; wherein starting positions or ending positions of the embedded chirp signals corresponding to different characters are different; the mother chirp signal is obtained by embedding a chirp signal into a background signal and comprises a frame header and frame data; the frame header comprises a plurality of ascending chirp signals and descending chirp signals; and sending the baseband signal to a receiving end through a channel, so that the receiving end demodulates the baseband signal to obtain a symbol word, and de-maps the bit of the symbol word to obtain a bit stream. According to the method, the spectrum efficiency is improved, the anti-interference capability is enhanced, and the emission power amplification efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and particularly to a multi - level in - pulse linear frequency modulation communication system. Background Art

[0002] The in - pulse linear frequency modulation (Chirp) communication system is a common communication method, and its basic principle is to transmit information by linearly changing the signal frequency. In the prior art, common modulation methods include: binary, multi - level, frequency hopping, etc.

[0003] The modulation waveforms in Chirp communication mainly include the following common types, and these waveforms have unique characteristics and advantages in different application scenarios and modulation methods:

[0004] 1) Linear frequency modulation (LFM) Chirp signal:

[0005] Definition: The linear frequency modulation Chirp signal is a signal whose frequency changes linearly with time, and its frequency can linearly increase (up - chirp) or linearly decrease (down - chirp).

[0006] Mathematical expression:

[0007]

[0008] Where: A is the amplitude of the signal; f0 is the initial frequency; k is the frequency change rate (frequency modulation slope), k = T / B, where B is the bandwidth of the signal and T is the duration of the signal; t is the time.

[0009] Characteristics: It has good time - frequency resolution and is suitable for pulse compression technology in radar and communication systems; it has strong anti - interference ability and can maintain good communication performance in a complex electromagnetic environment.

[0010] Application scenarios: Target detection and distance measurement in radar systems; spread - spectrum communication technology in wireless communication.

[0011] 2) Multi - level modulation Chirp signal:

[0012] Definition: The multi - level modulation Chirp signal represents different symbols by introducing multiple discrete frequency offsets on the basis of the Chirp signal.

[0013] Mathematical expression:

[0014]

[0015] Where, Δf m is the frequency offset of the m - th symbol, and usually there are M different offset frequencies corresponding to M symbols.

[0016] Features: Improve spectral efficiency and be able to transmit more information within the same bandwidth; achieve higher data transmission rates by increasing the number of symbols.

[0017] Application scenarios: High-speed wireless communication systems, such as LoRa spread-spectrum communication; low-power wide-area network (LPWAN) communication in the Internet of Things (IoT).

[0018] 3) Binary orthogonal keying (BOK) Chirp signal:

[0019] Definition: The binary orthogonal keying Chirp signal uses Chirp signals with positive and negative slopes to represent binary data symbols "1" and "0".

[0020] Mathematical expression:

[0021]

[0022] Features: Utilize the orthogonality of Chirp signals to achieve simple demodulation; have strong anti-interference ability and are suitable for use in low signal-to-noise ratio environments. However, the transmission speed of the binary orthogonal keying (BOK) Chirp signal is slow.

[0023] Application scenarios: Binary data transmission in digital communication systems; target recognition and data transmission in radar systems.

[0024] 4) Direct modulation (DM) Chirp signal:

[0025] Definition: The direct modulation Chirp signal directly uses the process of stretching and compressing Chirp pulses for spread-spectrum modulation, combining data modulation and spread-spectrum modulation.

[0026] Mathematical expression:

[0027]

[0028] where d(t) is the data modulation signal.

[0029] Features: Facilitate the use of the multi-dimensional orthogonality of Chirp signals to achieve multi-dimensional modulation and multi-access applications; can flexibly adjust the spreading factor to adapt to different communication requirements.

[0030] Application scenarios: Spread-spectrum communication systems, such as ultra-wideband (UWB) communication; communication systems with multi-user access, achieving multi-access through different Chirp parameters.

[0031] 5) Frequency-hopping Chirp signal:

[0032] Definition: The frequency-hopping Chirp signal is based on the Chirp signal and realizes modulation by changing the frequency-hopping points at different time intervals.

[0033] Mathematical expression:

[0034]

[0035] Among them, f jump (t) is the frequency-hopping function, indicating the frequency hopping at a specific time point.

[0036] Features: It improves the anti-interference ability and concealment of the signal, and is suitable for use in complex electromagnetic environments; it can implement various modulation methods through different hopping patterns.

[0037] Application scenarios: Anti-interference and secure communication in military communication; spectrum sensing and spectrum sharing systems.

[0038] However, the intra-pulse linear frequency modulation (Chirp) communication system has the following disadvantages:

[0039] (1) Low spectral efficiency: Binary and multi-level modulation methods are difficult to expand, and the amount of information transmitted is difficult to meet the requirements of high-speed communication.

[0040] (2) The deformation of the modulation waveform reduces the anti-interference ability: The multi-level and direct modulation methods cause changes in the linearity of the waveform in the frequency domain, resulting in a decrease in the peak value during the correlation demodulation operation at the receiving end, thus reducing the anti-interference ability.

[0041] (3) The deformation of the modulation waveform reduces the efficiency of the transmitting power amplifier: The multi-level and direct modulation waveforms have large changes in the wave packet amplitude and large average-to-peak ratio, resulting in a decrease in the efficiency of the transmitting power amplifier at the transmitting end. The frequency-hopping Chirp signal modulation will cause distortion of the transmitted signal spectrum and reduce the transmitting efficiency of the power amplifier.

[0042] Therefore, it is impossible to achieve high spectral efficiency, strong anti-interference ability, and high transmitting power amplifier efficiency at the same time. Summary of the Invention

[0043] Based on this, in view of the above technical problems, a multi-level intra-pulse linear frequency modulation communication method is provided to simultaneously improve spectral efficiency, enhance anti-interference ability, and improve the efficiency of the transmitting power amplifier.

[0044] In a first aspect, a multi-level intra-pulse linear frequency modulation communication method is applied to a transmitting end, and the method includes:

[0045] Receiving the bit stream sent from the baseband processing module, and performing bit mapping on the bit stream to convert the bit stream into a symbol word;

[0046] Generate an embedded chirp signal according to the symbol word, and embed the embedded chirp signal into the frame data of a pre-generated mother chirp signal to generate a baseband signal; wherein, the starting position or the ending position of the embedded chirp signal corresponding to different character words is different; the mother chirp signal is obtained by embedding a chirp signal into a background signal, and includes a frame header and frame data; the frame header includes a plurality of rising chirp signals and falling chirp signals.

[0047] Transmit the baseband signal through a channel to a receiving end, so that the receiving end demodulates the baseband signal to obtain the symbol word, and performs bit demapping on the symbol word to obtain a bit stream.

[0048] In the above solution, optionally, before converting the bit stream into a symbol word, it further includes: scrambling, CRC, signal encoding, and interleaving processing on the received bit stream.

[0049] After the receiving end demodulates the baseband signal to obtain the symbol word and performs bit demapping on the symbol word to obtain a bit stream, it further includes: enabling the receiving end to perform deinterleaving, channel decoding, de-CRC, and descrambling processing on the bit stream obtained by bit demapping, and outputting the processed bit stream.

[0050] In the above solution, optionally, performing bit mapping on the bit stream to convert the bit stream into a symbol word specifically includes:

[0051] Group the bit stream according to a certain bit width, and record each group of bit streams as 1 codeword to obtain a plurality of codewords;

[0052] Divide the plurality of codewords according to a preset chip width, and record each group of codewords as 1 chip to obtain a plurality of chips;

[0053] Convert each chip into a multi-base integer; map the multi-base integer to a predefined small interval by using a preset mapping method, and take any set position point in the small interval as the symbol word.

[0054] In the above solution, further optionally, the preset mapping method covers various mapping methods, including: sequential mapping, non-linear mapping, and interleaving mapping.

[0055] In the above solution, further optionally, the multi-base integer includes various number system forms, including: decimal integer, binary integer, and hexadecimal integer.

[0056] In the above solution, optionally, enabling the receiving end to demodulate the baseband signal to obtain the symbol word specifically includes:

[0057] Enabling the receiving end to perform the following steps:

[0058] Perform frame search, find the rising chirp signal in the frame header through convolution, and obtain the frequency offset of the rising chirp signal in the frame header;

[0059] After compensating the frequency offset of the baseband signal with the frequency offset of the rising chirp signal in the frame, obtain the time delay offset values of multiple chirp signals in the frame header of the baseband signal;

[0060] After compensating the frequency offset and time delay offset of the baseband signal, sequentially obtain the falling signals in the frame header, and calculate the frequency offset of the falling signals;

[0061] Calculate the average value of the frequency offset of the rising signal and the frequency offset of the falling signal to obtain the final frequency offset compensation value; calculate the time delay offset values of multiple chirp signals in the frame header by using the average value method;

[0062] Compensate the baseband signal with the final frequency offset compensation value, compensate the time delay offset, and calculate the peak position of the embedded signal to obtain the symbol word.

[0063] In the above solution, optionally, the background signal covers various waveforms, including sine wave signals, noise signals, and level waves;

[0064] The embedded Chirp signal covers various types of waveforms, including: BOK waveform, DM Chirp waveform.

[0065] In the above solution, optionally, the method further includes: receiving modulation parameters to perform modulation according to the modulation parameters; the modulation parameters are obtained according to the channel conditions and communication requirements; the modulation parameters include: the start or end position of the embedded Chirp signal, the length of the Chirp signal, the waveform of the rising Chirp signal or the falling Chirp signal, the number of Chirp signals in the frame header, the number of rising Chirp signals in the frame header, the number of falling Chirp signals in the frame header, the bandwidth occupied by the signal, the frequency width occupied by the signal, the sampling rate, and the number of sampling points.

[0066] In a second aspect, a multi - level intra - pulse linear frequency modulation communication method is applied to the receiving end, and the method includes:

[0067] Receive the baseband signal sent by the transmitting end. The baseband signal is generated by the transmitting end through bit mapping of the bit stream received from the baseband processing module to convert the bit stream into a symbol word, then generating an embedded chirp signal according to the symbol word, and embedding the embedded chirp signal into the frame data of the pre-generated mother chirp signal to generate a baseband signal. Among them, the starting position or ending position of the embedded chirp signal corresponding to different character words is different. The mother chirp signal is obtained by embedding a chirp signal into a background signal and includes a frame header and frame data. The frame header includes multiple rising chirp signals and falling chirp signals.

[0068] Demodulate the baseband signal to obtain the symbol word, and perform bit demapping on the symbol word to obtain a bit stream.

[0069] In the above solution, optionally, demodulating the baseband signal to obtain the symbol word specifically includes:

[0070] Perform frame search, find the rising chirp signal in the frame header through convolution, and obtain the frequency offset of the rising chirp signal in the frame header.

[0071] After compensating the frequency offset of the baseband signal with the frequency offset of the rising chirp signal in the frame, obtain the time delay offset values of multiple chirp signals in the frame header of the baseband signal.

[0072] After compensating the frequency offset and time delay offset of the baseband signal, sequentially obtain the falling signals in the frame header, and calculate the frequency offset of the falling signals.

[0073] Calculate the average value of the frequency offset of the rising signal and the frequency offset of the falling signal to obtain the final frequency offset compensation value; calculate the time delay offset values of multiple chirp signals in the frame header by using the average value method.

[0074] Compensate the baseband signal with the final frequency offset compensation value, and compensate the time delay offset, and calculate the peak position of the embedded signal to obtain the symbol word.

[0075] This application has at least the following beneficial effects:

[0076] In this application, the symbol words of the bitstream are obtained through bit mapping, and then the embedded signals of the symbol words are calculated. The embedded signals are embedded into the background signal to generate a baseband signal. The start position and end position of the embedded signals are different to represent different symbol words. Thus, the baseband signal is sent from the transmitter to the receiver through the channel, and the receiver performs synchronization / embedded demodulation and bit demapping to obtain the bitstream. Therefore, by adopting embedded Chirp modulation and multi - level modulation, more information can be transmitted within the same bandwidth, thereby improving the data transmission rate without increasing the transmission power, significantly improving the spectral efficiency, and improving the overall performance of the communication system without increasing the transmission power, indirectly improving the efficiency of the transmitting power amplifier. Moreover, this method makes the signal have a wider bandwidth in the frequency domain, and the wider bandwidth can disperse the influence of interference, reduce the damage of interference to the signal, and improve the anti - interference ability. At the same time, bit mapping and demapping can also improve the anti - interference ability.

[0077] Adopt the multi - level modulation method to convert the bitstream into codewords and then map the codewords to symbol words. Each symbol can carry more bit information, thus achieving a higher data transmission rate within the same bandwidth and improving the spectral efficiency.

[0078] Search for the rising Chirp header through convolution to complete frame search, and obtain the frequency offset of the rising Chirp signal. After compensating for the frequency offset of the received signal with the falling Chirp signal in the frame, further search for the delay offset value through frequency - domain correlation. This precise synchronization and compensation mechanism can effectively eliminate the frequency and delay changes in the channel and improve the anti - interference ability of the signal.

[0079] At the transmitter, through basic processing steps such as scrambling, CRC (Cyclic Redundancy Check), and signal encoding, the redundancy of the signal is increased. The interleaving technique can effectively reduce the impact of burst interference. Even if some symbols are interfered with, it will not cause errors in the entire data frame. Description of the Drawings

[0080] Figure 1 It is a flowchart of a multi - level in - pulse linear frequency modulation communication method provided by an embodiment of this application;

[0081] Figure 2 It is a specific flowchart of the receiver and transmitter of a multi - level in - pulse linear frequency modulation communication method provided by an embodiment of this application;

[0082] Figure 3 It is a schematic diagram of the embedded signal embedding process provided by an embodiment of this application;

[0083] Figure 4 It is a schematic diagram of the baseband signal provided by an embodiment of this application;

[0084] Figure 5 Block diagram of bit mapping principle provided by an embodiment of the present application;

[0085] Figure 6 Step diagram of embedded signal demodulation provided by an embodiment of the present application. Detailed implementation manners

[0086] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0087] In one embodiment, as Figure 1 and Figure 2 shown, a multi - ary in - pulse linear frequency modulation communication method is provided, which is characterized in that it is applied to the sending end, and the method includes:

[0088] Step S1: Receive the bit stream sent from the baseband processing module, perform bit mapping on the bit stream to convert the bit stream into a symbol word;

[0089] Step S2: Generate an embedded chirp signal according to the symbol word, and embed the embedded chirp signal into the frame data of the pre - generated mother chirp signal to generate a baseband signal; wherein, the starting position or the ending position of the embedded chirp signal corresponding to different character words is different; the mother chirp signal is obtained by embedding a chirp signal into a background signal, including a frame header and frame data; the frame header includes a plurality of rising chirp signals and falling chirp signals;

[0090] Step S3: Transmit the baseband signal through a channel to the receiving end, so that the receiving end demodulates the baseband signal to obtain the symbol word, and performs bit demapping on the symbol word to obtain a bit stream.

[0091] In this embodiment, as Figure 3 shown, multi - ary modulation adopts the method of embedding chirp to support multi - ary modulation. First, generate a mother chirp, and then embed a symbol chirp into it. The symbol chirp can be selected as a chirp with an ascending slope or a descending slope; the starting or ending position of the embedded chirp corresponding to the symbol word generates different symbols, and more information can be transmitted within the same bandwidth, thereby improving the spectral efficiency.

[0092] As Figure 4As shown in the figure, it is the structural diagram of the baseband signal. A complete frame consists of a frame header and frame data. The frame header is composed of an unchanged rising chirp and a falling chirp, and parameters such as the number, time length, and bandwidth of the rising chirp and the falling chirp can be set according to user requirements. The frame data is composed of embedded chirps, which can be one or more, and is set according to the specific communication system.

[0093] In the above-mentioned multi - level intra - pulse linear frequency - modulation communication system, the symbol word of the bit stream is obtained through bit mapping, and then the embedded signal of the symbol word is calculated. The embedded signal is embedded into the background signal to generate the baseband signal. The start position and end position of the embedded signal are different to represent different symbol words. Thus, the baseband signal is sent from the transmitter to the receiver through the channel, and the receiver performs synchronization / embedded demodulation and bit demapping to obtain the bit stream. Therefore, by adopting embedded Chirp modulation and multi - level modulation, more information can be transmitted within the same bandwidth, thereby improving the data transmission rate without increasing the transmission power, significantly improving the spectral efficiency, and improving the overall performance of the communication system without increasing the transmission power, indirectly improving the efficiency of the transmitting power amplifier. Moreover, this method makes the signal have a wider bandwidth in the frequency domain. A wider bandwidth can disperse the influence of interference, reduce the damage of interference to the signal, and improve the anti - interference ability. At the same time, anti - interference ability can also be improved through bit mapping and demapping.

[0094] In one embodiment, as Figure 2 shown, before converting the bit stream into a symbol word, it further includes: scrambling, CRC, signal encoding, and interleaving processing on the received bit stream;

[0095] After the receiver demodulates the baseband signal to obtain the symbol word and performs bit demapping on the symbol word to obtain the bit stream, it further includes: enabling the receiver to perform de - interleaving, channel decoding, de - CRC, and descrambling processing on the bit stream obtained by bit demapping, and outputting the processed bit stream.

[0096] In one embodiment, as Figure 5 shown, performing bit mapping on the bit stream to convert the bit stream into a symbol word specifically includes:

[0097] Grouping the bit stream according to a certain bit width, and each group of bit stream is recorded as 1 code word to obtain multiple code words;

[0098] Dividing the multiple code words according to the preset chip width, and each group of code words is recorded as 1 chip to obtain multiple chips;

[0099] Convert each chip into a multi - base integer; map the multi - base integer to a predefined small interval using a preset mapping method, and take any set position point in the small interval as a symbol word.

[0100] Specifically, the principle of bit mapping is shown in the following figure and is specifically divided into 3 steps:

[0101] 1) Convert the bit stream into code words. The sending end receives the transmitted bit stream from the previous baseband processing module, groups the bit stream according to a certain bit width, such as 8 bits, and each group is 1 code word;

[0102] 2) Convert the code words into chips. Re - divide and combine the code words according to the chip width specified by the system. Take the bit width as N, corresponding to a certain integer interval on the 1 - D number axis, such as 1 to 512 in the following figure;

[0103] 3) Convert the chips into symbol words. Divide the integer interval in step 2) into 2^N small intervals, convert the chips into corresponding decimal integers (or other - base integers), and then map the integers to the small intervals correspondingly; the mapping method can be selected as sequential mapping. As shown in the following figure, integer 0 corresponds to small intervals 1 - 4, integer 1 corresponds to small intervals 5 - 8, integer 2 corresponds to small intervals 9 - 12 (the mapping method can also be selected as non - linear mapping, interleaving mapping, etc.); then select the mid - point of the corresponding small interval as the symbol word (other points can also be selected);

[0104] In one embodiment, the preset mapping method covers a variety of mapping methods, including: sequential mapping, non - linear mapping, and interleaving mapping.

[0105] In one embodiment, the multi - base integer includes a variety of number - system forms, including: decimal integer, binary integer, and hexadecimal integer.

[0106] In one embodiment, performing bit demapping on the symbol word to obtain a bit stream includes: using reverse bit mapping to perform bit demapping on the symbol word to obtain a bit stream.

[0107] In one embodiment, as Figure 6 shown, so that the receiving end demodulates the baseband signal to obtain the symbol word specifically includes:

[0108] So that the receiving end is used to perform the following steps:

[0109] Perform frame search, find the rising chirp signal in the frame header through convolution, and obtain the frequency offset of the rising chirp signal in the frame header;

[0110] After compensating for the frequency offset of the baseband signal by using the frequency offset of the rising chirp signal in the frame, obtain the delay offset values of multiple chirp signals in the frame header of the baseband signal;

[0111] After compensating for the frequency offset and delay offset of the baseband signal, sequentially obtain the falling signals in the frame header, and calculate the frequency offset of the falling signals;

[0112] Calculate the average value of the frequency offset of the rising signal and the frequency offset of the falling signal to obtain the final frequency offset compensation value; use the average value method to calculate the delay offset values of multiple chirp signals in the frame header;

[0113] Compensate the baseband signal with the final frequency offset compensation value, and compensate for the delay offset, and calculate the peak position of the embedded signal to obtain the symbol word.

[0114] In one embodiment, the background signal covers a variety of waveforms, including sine wave signals, noise signals, and level waves.

[0115] The embedded Chirp signal covers a variety of waveform types, including: BOK waveform, DM Chirp waveform.

[0116] In one embodiment, the method further includes: receiving the modulation method and system parameters; the method further includes: receiving modulation parameters to perform modulation according to the modulation parameters; the modulation parameters are obtained according to the channel conditions and communication requirements; the modulation parameters include: the starting or ending position of the embedded Chirp signal, the length of the Chirp signal, the waveform of the rising Chirp signal or the falling Chirp signal, the number of frame header Chirp signals, the number of frame header rising Chirp signals, the number of frame header falling Chirp signals, the bandwidth occupied by the signal, the frequency width occupied by the signal, the sampling rate, and the number of sampling points.

[0117] This application can also adopt adaptive modulation technology: dynamically adjust the modulation method and system parameters according to the channel conditions and communication requirements to achieve the best communication performance.

[0118] This application can also adopt joint modulation and coding technology: combine technologies such as multi - level in - pulse linear frequency modulation and forward error correction coding to further improve the reliability and anti - interference ability of the system.

[0119] This application can also adopt multi - carrier modulation technology to combine multi - level in - pulse linear frequency modulation with multi - carrier modulation technologies such as orthogonal frequency division multiplexing (OFDM) to meet more complex communication scenarios and higher communication requirements.

[0120] The advantages of this application are:

[0121] 1. Multilevel modulation method: Adopting a multilevel modulation waveform based on embedded Chirp to improve anti-interference ability, communication distance, and scalability of communication rate is one of the core innovations of this application.

[0122] 2. Chirp signal design: By designing the Chirp signal to improve the anti-interference ability of the signal and simplify the signal processing process is another key point of this application.

[0123] 3. System parameter optimization: Further improving the performance of the system by optimizing system parameters is an important technical means of this application.

[0124] 4. Extended technical solutions: Include adaptive modulation technology, joint modulation and coding technology, multicarrier modulation technology, etc. These extended technical solutions further expand the application scope and performance advantages of this application and are also important contents to be protected by this application.

[0125] In one embodiment, a multilevel in-pulse Chirp communication method is provided, which is applied to the receiving end. The method includes:

[0126] Receiving the baseband signal sent by the sending end. The baseband signal is that the sending end performs bit mapping on the bit stream received from the baseband processing module to convert the bit stream into a symbol word, then generates an embedded chirp signal according to the symbol word, and embeds the embedded chirp signal into the frame data of the pre-generated mother chirp signal to generate the baseband signal; wherein, the starting position or the ending position of the embedded chirp signal corresponding to different character words is different; the mother chirp signal is obtained by embedding the chirp signal into the background signal and includes a frame header and frame data; the frame header includes a plurality of rising chirp signals and falling chirp signals;

[0127] Demodulating the baseband signal to obtain the symbol word, and performing bit demapping on the symbol word to obtain the bit stream.

[0128] The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0129] The above-described embodiments only represent several implementation manners of this application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several deformations and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application patent should be subject to the appended claims.

Claims

1. A multi - base intra - pulse linear frequency modulation communication method, characterized in that, Applied to the transmitting end, the method includes: Receiving a bit stream sent from a baseband processing module, and performing bit mapping on the bit stream to convert the bit stream into a symbol word; Generating an embedded chirp signal according to the symbol word, and embedding the embedded chirp signal into the frame data of a pre-generated mother chirp signal to generate a baseband signal; wherein, the starting position or the ending position of the embedded chirp signal corresponding to different symbol words is different; the mother chirp signal is obtained by embedding a chirp signal into a background signal, and includes a frame header and frame data; the frame header includes a plurality of rising chirp signals and falling chirp signals; Transmitting the baseband signal through a channel to the receiving end, so that the receiving end demodulates the baseband signal to obtain the symbol word, and performs bit demapping on the symbol word to obtain a bit stream.

2. The multi - level intra - pulse linear frequency modulation communication method according to claim 1, characterized in that, Before converting the bit stream into a symbol word, it further includes: scrambling, CRC, signal encoding, and interleaving processing on the received bit stream; After the receiving end demodulates the baseband signal to obtain the symbol word, and performs bit demapping on the symbol word to obtain a bit stream, it further includes: enabling the receiving end to perform de-interleaving, channel decoding, de-CRC, and descrambling processing on the bit stream obtained by bit demapping, and outputting the processed bit stream.

3. The multi - level intra - pulse linear frequency modulation communication method according to claim 1, characterized in that, Performing bit mapping on the bit stream to convert the bit stream into a symbol word specifically includes: Grouping the bit stream according to a certain bit width, and each group of bit streams is recorded as 1 code word to obtain a plurality of code words; Dividing the plurality of code words according to a preset chip width, and each group of code words is recorded as 1 chip to obtain a plurality of chips; Converting each chip into a multi-valued integer; mapping the multi-valued integer to a predefined small interval by using a preset mapping method, and taking any set position point in the small interval as the symbol word.

4. The multi - level intra - pulse linear frequency modulation communication method according to claim 3, wherein, The preset mapping method covers a variety of mapping methods, including: sequential mapping, non-linear mapping, and interleaving mapping.

5. The multi - base intra - pulse linear frequency modulation communication method according to claim 3, characterized in that, The multi-valued integer includes a variety of number system forms, including: decimal integer, binary integer, and hexadecimal integer.

6. The multi - level intra - pulse linear frequency modulation communication method according to claim 1, wherein Enabling the receiving end to demodulate the baseband signal to obtain the symbol word specifically includes: Enabling the receiving end to perform the following steps: Performing frame search, finding the rising chirp signal in the frame header through convolution, and obtaining the frequency offset of the rising chirp signal in the frame header; After compensating the frequency offset of the baseband signal by using the frequency offset of the rising chirp signal in the frame, obtaining the delay offset values of a plurality of chirp signals in the frame header of the baseband signal; After compensating the frequency offset and the delay offset of the baseband signal, sequentially obtaining the falling signals in the frame header, and calculating the frequency offset of the falling signals; Calculating the average value of the frequency offset of the rising signal and the frequency offset of the falling signal to obtain the final frequency offset compensation value; calculating the delay offset values of a plurality of chirp signals in the frame header by using the average value method; Compensating the baseband signal by using the final frequency offset compensation value, compensating the delay offset, and calculating the peak position of the embedded signal to obtain the symbol word.

7. The multi - level intra - pulse linear frequency modulation communication method according to claim 1, characterized in that, The background signal covers a variety of waveforms, including sine wave signals, noise signals, and level waves; The embedded Chirp signal covers a variety of waveform types, including: BOK waveform, DM Chirp waveform.

8. The multi - base intra - pulse linear frequency modulation communication method according to claim 1, characterized in that, The method further includes: receiving modulation parameters for modulation according to the modulation parameters; the modulation parameters are obtained according to channel conditions and communication requirements; the modulation parameters include: the start or end position of the embedded Chirp signal, the Chirp signal length, the rising Chirp signal or falling Chirp signal waveform, the number of frame header Chirp signals, the number of rising frame header Chirp signals, the number of falling frame header Chirp signals, the bandwidth occupied by the signal, the frequency bandwidth occupied by the signal, the sampling rate, and the number of sampling points.

9. A multi - base intra - pulse linear frequency modulation communication method, characterized in that, Applied to the receiving end, the method includes: Receiving the baseband signal sent by the sending end, where the baseband signal is obtained by the sending end performing bit mapping on the bit stream received from the baseband processing module to convert the bit stream into a symbol word, then generating an embedded chirp signal according to the symbol word, and embedding the embedded chirp signal into the frame data of a pre-generated mother chirp signal to generate a baseband signal; where the start position or end position of the embedded chirp signal corresponding to different character words is different; the mother chirp signal is obtained by embedding a chirp signal into a background signal, including a frame header and frame data; the frame header includes a plurality of rising chirp signals and falling chirp signals; Demodulating the baseband signal to obtain the symbol word, and performing bit demapping on the symbol word to obtain a bit stream.

10. The multi - base intra - pulse linear frequency modulation communication method according to claim 9, wherein, Demodulating the baseband signal to obtain the symbol word specifically includes: Performing frame search, finding the rising chirp signal in the frame header through convolution, and obtaining the frequency offset of the rising chirp signal in the frame header; After compensating the frequency offset of the baseband signal with the frequency offset of the rising chirp signal in the frame, obtaining the time delay offset values of a plurality of chirp signals in the frame header of the baseband signal; After compensating the frequency offset and time delay offset of the baseband signal, sequentially obtaining the falling signals in the frame header and calculating the frequency offset of the falling signals; Calculating the average value of the frequency offset of the rising signal and the frequency offset of the falling signal to obtain the final frequency offset compensation value; calculating the time delay offset values of a plurality of chirp signals in the frame header by using the average value method; Compensating the baseband signal with the final frequency offset compensation value, compensating the time delay offset, and calculating the peak position of the embedded signal to obtain a symbol word.

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