Composite signal modulation and demodulation method

Abstract

The invention provides a composite signal modulation and demodulation method. The method comprises the following steps: dividing an input digital signal into three sub-signal sequences; performing amplitude keying modulation, phase offset keying modulation and pulse characteristic modulation on the sub-signal sequences to generate three modulation signals; generating a composite carrier signal through combination of frequency division multiplexing and time division multiplexing; the signals are sent after power amplification and radio frequency processing; the receiver performs low-noise amplification and down-conversion processing on the received signal; extracting three demodulation components through a digital filter and a time domain separation algorithm; respectively executing amplitude judgment demodulation, phase difference decomposition and pulse feature identification demodulation on the demodulation component; dynamically adjusting a demodulation sequence according to the channel noise level; and finally, recombining into an original digital signal sequence according to a preset rule. According to the invention, the anti-interference capability and transmission efficiency of signal transmission can be improved, and the adaptability and reliability of the system in a complex channel environment are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of digital signal processing and communication technologies, and more specifically, the present invention relates to a method for modulating and demodulating composite signals. Background Art

[0002] In modern communication technologies, signal modulation and demodulation are key links in realizing information transmission. Traditional modulation methods, such as amplitude shift keying (ASK), phase shift keying (PSK), and pulse modulation, etc., although widely used in their respective fields, a single modulation method often has difficulty in simultaneously meeting the comprehensive requirements of high transmission efficiency, strong anti-interference ability, and adapting to complex channel environments. For example, ASK is relatively sensitive to channel attenuation, PSK has limited performance in a low signal-to-noise ratio environment, and pulse modulation may cause signal distortion due to time slot conflicts. In addition, the fixed setting of modulation parameters in the prior art cannot be flexibly adjusted according to the dynamic changes of the channel, further restricting the overall performance of the system.

[0003] In the process of implementing the embodiments of the present invention, the inventors found that there are at least the following problems or defects in the prior art: a single modulation method is difficult to balance the transmission requirements in various complex scenarios, and there is a lack of a dynamic optimization mechanism for modulation parameters, resulting in limited signal transmission efficiency and reliability. Summary of the Invention

[0004] The present invention provides a method for modulating and demodulating composite signals, including: S1. Signal segmentation: dividing the input digital signal sequence into a first sub-signal sequence, a second sub-signal sequence, and a third sub-signal sequence; S2. Modulation processing: performing amplitude shift keying modulation on the first sub-signal sequence to generate a first modulated signal, performing phase shift keying modulation on the second sub-signal sequence to generate a second modulated signal, and performing pulse feature modulation on the third sub-signal sequence to generate a third modulated signal; S3. Signal synthesis: combining the first modulated signal, the second modulated signal, and the third modulated signal through frequency division multiplexing and time division multiplexing to generate a composite carrier signal; S4. Signal transmission: performing power amplification and radio frequency processing on the composite carrier signal through a transmitter; S5. Signal reception: performing low-noise amplification and down-conversion processing on the received composite carrier signal by a receiver; S6. Signal decomposition: extracting a first demodulated component, a second demodulated component, and a third demodulated component from the processed composite carrier signal through a digital filter and a time-domain separation algorithm; S7. Demodulation processing: respectively performing amplitude decision demodulation on the first demodulated component, performing phase difference demodulation on the second demodulated component, and performing pulse feature recognition demodulation on the third demodulated component; S8. Logical judgment: Dynamically adjust the execution order of the amplitude decision demodulation, phase difference demodulation, and pulse feature recognition demodulation according to the channel noise level; S9. Signal restoration: Recombine the three demodulated sub-signal sequences into the original digital signal sequence according to a preset rule.

[0005] As a further improvement of the present application, the S1 signal segmentation specifically includes: S11. Divide the input digital signal sequence into three consecutive signal segments according to a preset ratio; S12. Perform cyclic redundancy check encoding on each signal segment to generate a check code; S13. Add a synchronization header identifier to the head of each signal segment; S14. Define the three signal segments with the synchronization header added as the first sub-signal sequence, the second sub-signal sequence, and the third sub-signal sequence respectively.

[0006] As a further improvement of the present application, the amplitude shift keying modulation in S2 includes: S21. Set the reference amplitude and the modulation index , ; S22. Establish an amplitude mapping function , where is the modulation amplitude of the th symbol; is the reference amplitude; is the modulation index, indicating the amplitude of the amplitude change; is the value of the th symbol in the first sub-signal sequence; S23. Generate a modulation waveform according to the formula: , , where is the amplitude shift keying modulation signal; is the carrier frequency; is the symbol period; is the time variable.

[0007] As a further improvement of the present application, the phase shift keying modulation in S2 includes: S24. Set the phase difference factor ; S25. Establish a phase recurrence formula , where is the phase of the th symbol; is the phase difference factor, indicating the phase difference between adjacent symbols; is the The value of a symbol; S26. Generate a modulation waveform according to the following formula: , , where is a phase shift keying modulation signal; is the carrier frequency; is the symbol period; is the time variable.

[0008] As a further improvement of this application, the pulse feature modulation in S2 includes: S27. Set a reference pulse width and a pulse interval ; S28. Establish a pulse parameter calculation formula: the pulse width , where is the actual width of the th pulse; is the reference pulse width; is the value of the th symbol in the third sub-signal sequence; Calculate the pulse interval according to the following formula: , where is the actual interval of the th pulse; is the reference pulse interval; S29. Generate a modulation waveform according to the following formula: , where is the pulse modulation signal; is the Dirac function, representing the starting point of the pulse; is the rectangular pulse function, representing the shape of the pulse; is the starting time of the th pulse.

[0009] As a further improvement of this application, the S3 signal synthesis includes: S31. Allocate frequency bands to the first modulation signal , the second modulation signal to the frequency band , and the third modulation signal to the time slot , where is the starting frequency of the first and second modulation signals; is the frequency band width; is the starting time of the time slot; is the time slot index; is the pulse interval; S32. Perform orthogonal frequency division multiplexing on the first and second modulation signals in the frequency domain; S33. Perform time-division multiplexing on the third modulation signal in the time domain; S34. Generate a composite carrier signal through the following formula: where, is the composite carrier signal; are amplitude shift keying, phase shift keying, and pulse modulation signals respectively.

[0010] As a further improvement of this application, the S6 signal decomposition includes: S61. Use a matched filter bank to perform frequency band separation on the composite signal, and extract the ASK frequency band component and the PSK frequency band component; S62. Use a time slot detection algorithm to identify the time domain position of the pulse signal; S63. Perform envelope detection on the ASK component to obtain the first demodulation component; S64. Perform coherent demodulation on the PSK component to obtain the second demodulation component; S65. Perform integral decision on the pulse component to obtain the third demodulation component.

[0011] As a further improvement of this application, the S8 logical judgment includes: S81. Calculate the signal-to-noise ratio of each component , , , corresponding to the signal-to-noise ratios of the ASK, PSK, and PULSE components respectively; S82. When threshold , demodulate in the order of ASK, PSK, PULSE in sequence; S83. When , preferentially demodulate the component with the highest signal-to-noise ratio; S84. When a time slot conflict of the pulse component is detected, start the time slot reallocation protocol.

[0012] As a further improvement of this application, the dynamic adjustment of the modulation index includes: S91. Real-time monitor the channel attenuation factor ; S92. Update the modulation index according to the following formula; ; where, is the channel attenuation factor; is the reference attenuation value; S93. When , switch to the fixed amplitude modulation mode.

[0013] As a further improvement of this application, the phase difference factor Optimizations include: S101. Statistically calculate the phase jump variable of consecutive symbols according to the following formula; ; where is the phase jump of the th symbol; is the phase of the th symbol; S102. Calculate the phase jump variance according to the following formula; , where is the variance of the phase jump; S103. Update the phase difference factor according to the following formula, ; where is the updated phase difference factor; is the current phase difference factor; is the target variance value.

[0014] According to the above embodiments of the present invention, there are at least the following beneficial effects: The composite signal modulation and demodulation method of the present invention can effectively improve the anti-interference ability and reliability of signal transmission. By dividing the digital signal into multiple sub-signal sequences and respectively using amplitude shift keying modulation, phase shift keying modulation, and pulse feature modulation, and combining frequency division multiplexing and time division multiplexing technologies to generate a composite carrier signal, it can achieve efficient information transmission in a complex channel environment. At the same time, this method can dynamically adjust the demodulation order according to the channel noise level and preferentially demodulate the component with the highest signal-to-noise ratio, thereby further optimizing the signal demodulation effect and improving the overall performance of the system.

[0015] In addition, the present invention can also enhance the adaptability of the signal to channel changes by real-time monitoring of the channel state and dynamically adjusting parameters such as the modulation index and phase difference factor. This dynamic adjustment mechanism enables the system to maintain a stable transmission efficiency under different channel conditions, while reducing the bit error rate and ensuring the integrity and accuracy of the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] By referring to the following detailed description of the drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understood. In the drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, wherein: Figure 1 is a schematic flowchart of a composite signal modulation and demodulation method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and then implement the present invention, rather than limiting the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to be able to convey the scope of the present invention fully to those skilled in the art.

[0019] Those skilled in the art know that the embodiments of the present invention can be implemented as a system, device, equipment, method, or computer program product. Therefore, the present invention can be specifically implemented in the following forms, namely: complete hardware, complete software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0020] It should be noted that any number of elements in the drawings is for illustration rather than limitation, and any naming is only for distinction and does not have any limiting meaning.

[0021] The following refers to Figure 1 , Figure 1 is a schematic flowchart of a composite signal modulation and demodulation method provided for an embodiment of the present invention. As Figure 1 shown, a composite signal modulation and demodulation method 100 includes: S1 Signal splitting: splitting the input digital signal sequence into a first sub-signal sequence, a second sub-signal sequence, and a third sub-signal sequence; S2 Modulation processing: performing amplitude shift keying modulation on the first sub-signal sequence to generate a first modulation signal, performing phase shift keying modulation on the second sub-signal sequence to generate a second modulation signal, and performing pulse feature modulation on the third sub-signal sequence to generate a third modulation signal; S3 Signal synthesis: combining the first modulation signal, the second modulation signal, and the third modulation signal through frequency division multiplexing and time division multiplexing to generate a composite carrier signal; S4 Signal transmission: performing power amplification and radio frequency processing on the composite carrier signal through a transmitter; S5 Signal reception: performing low-noise amplification and down-conversion processing on the received composite carrier signal by a receiver; S6 Signal decomposition: extracting a first demodulation component, a second demodulation component, and a third demodulation component from the processed composite carrier signal through a digital filter and a time domain separation algorithm; S7 Demodulation processing: performing amplitude decision demodulation on the first demodulation component respectively, performing phase difference demodulation on the second demodulation component, and performing pulse feature recognition demodulation on the third demodulation component; S8 Logic judgment: dynamically adjusting the execution order of the amplitude decision demodulation, phase difference demodulation, and pulse feature recognition demodulation according to the channel noise level; S9 Signal Recovery: Recombine the three demodulated sub-signal sequences into the original digital signal sequence according to a preset rule.

[0022] It should be noted that the core of this method lies in splitting the input digital signal sequence into three sub-signal sequences and performing modulation processing on each of them separately. This splitting method can effectively disperse the complexity of the signal, making the subsequent modulation and demodulation processes more flexible and efficient. For example, Amplitude Shift Keying (ASK) is a modulation method that transmits information by changing the amplitude of the signal, while Phase Shift Keying (PSK) encodes information by changing the phase of the signal. Pulse Feature Modulation transmits information by adjusting the width or interval of the pulse. By splitting the signal and modulating it separately, the advantages of different modulation methods can be fully utilized to improve the reliability and anti-interference ability of signal transmission.

[0023] Specifically, the input digital signal sequence can be a binary sequence containing multiple symbols. In the signal splitting step, the sequence can be divided into three consecutive signal segments according to a preset ratio, such as in a 1:1:1 ratio. Each signal segment will then perform Cyclic Redundancy Check (CRC) encoding to generate a check code for error detection and correction. A synchronization header identifier is added to the head of each signal segment to identify the starting position of the signal at the receiving end. For Amplitude Shift Keying (ASK), a reference amplitude and modulation index can be set, where represents the amplitude change range, usually with a value range of . The modulation waveform can be generated through an amplitude mapping function, such as , where is the value of the -th symbol in the first sub-signal sequence. Similarly, Phase Shift Keying (PSK) can be achieved by setting a phase difference factor , whose value range is usually .

[0024] Preferably, in the signal splitting step, the splitting ratio can be adjusted according to actual application requirements, such as dividing the signal segments in a 2:1:1 or 3:2:1 ratio to optimize the signal transmission efficiency. In Amplitude Shift Keying (ASK), the modulation index can be dynamically adjusted according to the channel conditions. For example, when the channel attenuation is large, the value of is reduced to improve the anti-interference ability of the signal. For Phase Shift Keying (PSK), the phase difference factor can be optimized according to the phase jump characteristics of the signal. For example, by statistically analyzing the phase jump amount of consecutive symbols to dynamically adjust the value of , thereby further improving the transmission quality of the signal.

[0025] In some embodiments, the S1 signal segmentation specifically includes: S11 divides the input digital signal sequence into three consecutive signal segments according to a preset ratio; S12 performs cyclic redundancy check encoding on each signal segment to generate a check code; S13 adds a synchronization header identifier to the head of each signal segment; S14 defines the three signal segments with the synchronization header added as the first sub-signal sequence, the second sub-signal sequence, and the third sub-signal sequence respectively.

[0026] It should be noted that signal segmentation is a basic step of this method. Its purpose is to divide the input digital signal sequence into multiple sub-signal sequences for subsequent modulation processing respectively. Specifically, the input digital signal sequence is divided into three consecutive signal segments, and each signal segment corresponds to a different modulation method. This process not only helps to improve the flexibility of signal transmission but also enhances the anti-interference ability of the signal through the complementary advantages of multiple modulation methods. During the segmentation process, cyclic redundancy check encoding (CRC) is used to generate the check code, which is a commonly used error detection method that detects errors during transmission by adding redundant information to the data. The synchronization header identifier is used to quickly locate the starting position of the signal at the receiving end to ensure the correct demodulation of the signal.

[0027] Specifically, the signal segmentation step includes the following operations: First, divide the input digital signal sequence into three consecutive signal segments according to a preset ratio. For example, the signal sequence can be equally divided into three segments, and each segment contains the same number of symbols. Then, perform cyclic redundancy check encoding on each signal segment to generate the corresponding check code. CRC encoding generates redundant bits by calculating the remainder of polynomial division, and these redundant bits are appended to the end of the signal segment for error detection at the receiving end. Next, add a synchronization header identifier to the head of each signal segment, and this identifier is a predefined pattern used to quickly identify the starting position of the signal segment at the receiving end. In this way, the receiving end can accurately align the signal, thereby improving the accuracy and efficiency of demodulation.

[0028] Preferably, the ratio of signal segmentation can be adjusted according to the actual application requirements. For example, for some scenarios with high requirements for signal transmission efficiency, the signal sequence can be divided into sub-signal segments of different lengths, such as being allocated according to a ratio of 2:1:1 or 3:2:1. This non-equal segmentation method can optimize the signal transmission performance according to the characteristics of different modulation methods. In addition, when adding the synchronization header identifier, different modes can be selected to distinguish different signal segments, such as using different binary sequences as identifiers. At the same time, in order to further improve the error detection ability, an additional redundant check mechanism, such as parity check or Hamming code check, can be added on the basis of CRC coding to enhance the reliability of the signal.

[0029] In some embodiments, the amplitude shift keying modulation in S2 includes: S21 setting a reference amplitude and a modulation index , ; S22 establishing an amplitude mapping function , where: : the modulation amplitude of the th symbol; : the reference amplitude; : the modulation index, indicating the amplitude change range; : the value of the th symbol in the first sub-signal sequence; S23 generating a modulation waveform according to the formula: , , where: : the amplitude shift keying modulation signal; : the carrier frequency; : the symbol period; : the time variable.

[0030] It should be noted that amplitude shift keying modulation (ASK) is a key step in modulating the first sub-signal sequence in this method. ASK transmits information by changing the amplitude of the signal and is a simple and efficient modulation method. In this process, the reference amplitude and the modulation index are two core parameters. The reference amplitude determines the basic intensity of the modulation signal, while the modulation index controls the amplitude change range. The value range of the modulation index is usually between (0,1), indicating the relative size of the amplitude change. Through the amplitude mapping function , the symbol value in the first sub-signal sequence can be mapped to the modulated amplitude value, thereby generating the amplitude shift keying modulation signal. This modulation method can effectively utilize the amplitude change of the signal to transmit information while maintaining a high transmission efficiency.

[0031] Specifically, the parameter settings and modulation process of amplitude shift keying modulation are as follows: First, set the reference amplitude to a fixed reference value, such as 1V, to ensure that the modulation signal has sufficient strength. The modulation index needs to be optimized according to the channel conditions and transmission requirements. For example, in an environment with low channel noise, can be set to a value close to 1 to maximize the amplitude variation and thus improve the transmission efficiency of the signal; while in an environment with high channel noise, it is necessary to appropriately reduce the value of to avoid signal distortion. Through the amplitude mapping function , each symbol in the first sub-signal sequence can be mapped to the corresponding modulation amplitude . Subsequently, the modulation waveform is generated according to the formula , where is the carrier frequency and t is the time variable. In this way, the symbol sequence is effectively converted into a continuous modulation signal for subsequent signal synthesis and transmission.

[0032] Preferably, in order to further optimize the performance of amplitude shift keying modulation, a dynamic adjustment mechanism can be introduced. For example, the attenuation factor of the channel is monitored in real time, and the modulation index is dynamically updated according to the formula , where is the reference attenuation value. When the channel attenuation is small, the modulation index can be maintained at a high value to improve the transmission efficiency of the signal; while when the channel attenuation is large, the modulation index will automatically decrease to avoid signal distortion due to overmodulation. In addition, different carrier frequencies can be selected according to the actual application requirements. For example, a higher carrier frequency is selected in a high-frequency channel to improve the transmission rate, while a lower carrier frequency is selected in a low-frequency channel to reduce signal loss. Through these optimization measures, amplitude shift keying modulation can better adapt to different channel conditions, thereby improving the reliability and flexibility of signal transmission.

[0033] In some embodiments, the phase shift keying modulation in S2 includes: S24 sets the phase difference factor , ; S25 establishes a phase recurrence formula , where: : the phase of the th symbol; : Phase difference factor, representing the phase difference between adjacent symbols; : The value of the th symbol in the second sub-signal sequence; S26 generates a modulation waveform according to the formula: , , where: : Phase shift keying modulation signal; : Carrier frequency; : Symbol period; : Time variable.

[0034] It should be noted that phase shift keying modulation (PSK) is a key step in modulating the second sub-signal sequence in this method, and its core lies in transmitting information by changing the phase of the signal. In this process, the phase difference factor is an important parameter, which determines the phase difference between adjacent symbols. Through the phase recurrence formula , the symbol value in the second sub-signal sequence can be mapped to the phase value of the modulation signal. This modulation method can transmit information through phase changes while keeping the signal frequency unchanged, and has good anti-interference ability and high spectral efficiency.

[0035] Specifically, the parameter setting and modulation process of phase shift keying modulation are as follows: First, set the value range of the phase difference factor to be , and this parameter can be adjusted according to the transmission requirements of the signal and the characteristics of the channel. For example, when higher spectral efficiency is required, a larger value can be selected; while in an environment with high channel noise, selecting a smaller value can improve the anti-interference ability of the signal. Through the phase recurrence formula, the phase value corresponding to each symbol can be calculated. Subsequently, according to the formula generate a modulation waveform, where is the carrier frequency and is the time variable. In this way, the symbol sequence is converted into a modulation signal with different phases for subsequent signal synthesis and transmission.

[0036] Preferably, in order to further optimize the performance of phase shift keying modulation, a dynamic adjustment mechanism can be introduced. For example, by statistically calculating the phase jump variable of consecutive symbols, calculating the variance of the phase jump, and dynamically adjusting the phase difference factor according to the formula , where is the target variance value. This dynamic adjustment mechanism can optimize the phase difference factor in real time according to the actual signal transmission situation, thereby improving the signal transmission quality and anti-interference ability.

[0037] Furthermore, different carrier frequencies can be selected according to actual application requirements , for example, a higher carrier frequency is selected in a high-frequency channel to improve the transmission rate, while a lower carrier frequency is selected in a low-frequency channel to reduce signal loss. Through these optimization measures, phase shift keying modulation can better adapt to different channel conditions, thereby improving the reliability and flexibility of signal transmission.

[0038] In some embodiments, the pulse feature modulation in S2 includes: S27 sets the reference pulse width and the pulse interval ; S28 establishes a pulse parameter calculation formula: pulse width , where: : the actual width of the th pulse; : the reference pulse width; : the value of the th symbol in the third sub-signal sequence; pulse interval , where: : the actual interval of the th pulse; : the reference pulse interval; S29 generates a modulation waveform: , where: : the pulse modulation signal; : Dirac function, indicating the starting point of the pulse; : rectangular pulse function, indicating the shape of the pulse; : the starting time of the th pulse.

[0039] It should be noted that pulse feature modulation is a key step in modulating the third sub-signal sequence in this method, which transmits information by adjusting the width and interval of the pulse. The core of this modulation method lies in the dynamic adjustment of the actual width and interval of the pulse, which can effectively utilize the time domain resources and improve the signal transmission efficiency and anti-interference ability. During the modulation process, the reference pulse width and the pulse interval are two important parameters, which respectively determine the basic width of the pulse and the time interval between adjacent pulses. Through the pulse parameter calculation formula, the actual width and interval of the pulse can be dynamically adjusted according to the symbol values in the third sub-signal sequence, thereby generating a pulse modulation signal.

[0040] Specifically, the parameter settings and modulation process of pulse feature modulation are as follows: First, set the reference pulse width and the pulse interval . The reference pulse width is usually selected according to the transmission rate of the signal and the channel characteristics. For example, it can be set to 1 microsecond or a smaller value to meet the requirements of high-speed transmission. The pulse interval is adjusted according to the time slot allocation and transmission efficiency of the signal. For example, it can be set to several times the reference pulse width. For the calculation formula of the pulse width , where is the value of the i-th symbol in the third sub-signal sequence, which is used to dynamically adjust the actual width of the pulse. Similarly, the calculation formula of the pulse interval is used to adjust the actual interval of the pulse. Through these formulas, a series of pulse signals with dynamically changing widths and intervals can be generated. Finally, the pulse modulation signal is generated through the formula , where is the Dirac function, indicating the starting point of the pulse.

[0041] Preferably, in order to further optimize the performance of pulse feature modulation, more dynamic adjustment mechanisms can be introduced. For example, according to the time-varying characteristics of the channel, the reference pulse width and the pulse interval are adjusted in real time. When the channel noise is low, the pulse interval can be appropriately reduced to improve the transmission efficiency; while when the channel noise is high, the pulse interval is increased to enhance the anti-interference ability. In addition, an adaptive pulse shape design can be introduced. For example, Gaussian pulses or raised cosine pulses are used instead of rectangular pulses to reduce the mutual interference between pulses. For the adjustment coefficients of the pulse width and interval (such as 0.5 and 0.3), they can be optimized according to the actual application requirements. For example, in a high-density signal transmission scenario, these coefficients can be appropriately increased to further improve the dynamic range of the pulse. Through these optimization measures, pulse feature modulation can better adapt to different channel conditions, thereby improving the reliability and flexibility of signal transmission.

[0042] In some embodiments, the S3 signal synthesis includes: S31 allocates frequency bands to the first modulation signal , the second modulation signal , and allocates time slots to the third modulation signal , where: : The starting frequencies of the first and second modulation signals; : The frequency band width; : The starting time of the time slot; : The time slot index; : Pulse interval; S32 performs orthogonal frequency division multiplexing on the first and second modulation signals in the frequency domain; S33 performs time division multiplexing on the third modulation signal in the time domain; S34 generates a composite carrier signal through the formula where: : Composite carrier signal; : Are amplitude shift keying, phase shift keying, and pulse modulation signals respectively.

[0043] It should be noted that signal synthesis is a key step in integrating sub-signals processed by different modulation methods into a composite carrier signal. This process combines frequency division multiplexing (FDM) and time division multiplexing (TDM) to achieve efficient integration of multiple modulation signals. Frequency division multiplexing ensures that different modulation signals do not interfere with each other in the frequency domain by allocating different frequency bands to them; while time division multiplexing makes the signals transmit orderly in the time domain by allocating different time slots. This combination method makes full use of the resources in the frequency domain and time domain, improves the efficiency and reliability of signal transmission, and provides a basis for subsequent signal transmission and reception.

[0044] Specifically, the implementation process of signal synthesis includes the following key steps: First, allocate a frequency band for the first modulation signal (ASK), allocate a frequency band for the second modulation signal (PSK), and the third modulation signal (PULSE) is allocated a time slot . Among them, and are the starting frequencies of the first and second modulation signals respectively, is the frequency band width, is the starting time of the time slot, is the pulse interval. In the frequency domain, the ASK and PSK signals are synthesized through orthogonal frequency division multiplexing (OFDM) technology to ensure that they are orthogonal and do not interfere with each other in the frequency domain. In the time domain, the PULSE signal is inserted into the specified time slot through time division multiplexing. Finally, a composite carrier signal is generated through the formula where , and are amplitude shift keying, phase shift keying, and pulse modulation signals respectively. This synthesis method ensures the independence and integrity of each modulation signal during transmission.

[0045] Preferably, in order to further optimize the effect of signal synthesis, the allocation of frequency bands and time slots can be dynamically adjusted. For example, according to the actual transmission requirements of the signal and the channel characteristics, dynamically adjust the frequency band width and time slot interval In frequency band allocation, a more flexible frequency band allocation scheme can be selected according to the bandwidth requirements and spectrum utilization rate of the signal. For example, non-uniform frequency band allocation can be adopted to better adapt to the characteristics of different modulated signals. In time slot allocation, a time slot reallocation protocol can be introduced to address potential conflicts between pulse signals. In addition, a filter bank can be introduced during the frequency domain synthesis process to reduce signal leakage at the frequency band edge and improve spectrum efficiency. Through these optimization measures, the signal synthesis process can better adapt to complex channel environments, thereby improving the overall performance and reliability of signal transmission.

[0046] In some embodiments, the S6 signal decomposition includes: S61 Use a matched filter bank to perform frequency band separation on the composite signal, and extract the ASK frequency band component and the PSK frequency band component; S62 Use a time slot detection algorithm to identify the time domain position of the pulse signal; S63 Perform envelope detection on the ASK component to obtain the first demodulated component; S64 Perform coherent demodulation on the PSK component to obtain the second demodulated component; S65 Perform integration and decision on the pulse component to obtain the third demodulated component.

[0047] It should be noted that signal decomposition is a key step in separating the received composite carrier signal into individual modulated components, providing a basis for subsequent demodulation processing. This process is achieved through digital filters and time domain separation algorithms, and can accurately extract amplitude shift keying (ASK), phase shift keying (PSK), and pulse modulation (PULSE) signal components. Digital filters are used to separate signals in different frequency bands in the frequency domain, while time domain separation algorithms are used to identify and extract time division multiplexed signals. Through this combined method, each modulated signal can be effectively separated, providing accurate input for subsequent demodulation processing.

[0048] Specifically, the signal decomposition process includes the following key steps: First, a matched filter bank is used to separate the frequency bands of the composite signal, and the ASK frequency band component and the PSK frequency band component are extracted. The matched filter is an optimized linear filter that can maximize the signal-to-noise ratio of the output signal, thereby effectively separating signals in different frequency bands. For the ASK component, its modulation information is extracted through envelope detection, which is a commonly used demodulation method that recovers the original modulated signal by detecting the envelope change of the signal. For the PSK component, coherent demodulation is used. Coherent demodulation requires a local oscillator to provide a reference signal with the same frequency and phase as the received signal to accurately recover the phase information. For the pulse modulation signal, a time slot detection algorithm is used to identify the time domain position of the pulse signal, and pulse feature information is extracted through integration decision. Integration decision is a method that determines the signal characteristics through integration operations and can effectively extract the width and interval information of the pulse signal.

[0049] Preferably, in order to further optimize the accuracy and efficiency of signal decomposition, some improvement measures can be introduced. For example, during the frequency band separation process, the parameters of the matched filter, such as the center frequency and bandwidth, can be dynamically adjusted according to the spectral characteristics of the actual signal to better meet the signal separation requirements under different channel conditions. In time domain separation, more advanced time slot detection algorithms, such as time slot identification algorithms based on machine learning, can be used to improve the detection accuracy and anti-interference ability of pulse signals.

[0050] Furthermore, for the envelope detection and coherent demodulation processes, technologies such as adaptive gain control (AGC) and phase-locked loop (PLL) can be introduced to further improve the stability and reliability of demodulation. Through these optimization measures, the signal decomposition process can more efficiently separate each modulation component, thereby providing a higher quality signal input for subsequent demodulation processing.

[0051] In some embodiments, the S8 logical judgment includes: S81 Calculate the signal-to-noise ratio of each component 、 、 , corresponding to the signal-to-noise ratios of the ASK, PSK, and PULSE components respectively; S82 When threshold is satisfied, demodulate in the order of ASK → PSK → PULSE; S83 When is satisfied, preferentially demodulate the component with the highest signal-to-noise ratio; S84 When a time slot conflict of the pulse component is detected, start the time slot reallocation protocol.

[0052] It should be noted that logical judgment is the key step in dynamically adjusting the demodulation order according to the channel noise level in this method. This process optimizes the demodulation process and improves the reliability and efficiency of signal transmission by calculating the signal-to-noise ratio (SNR) of each modulation component and dynamically adjusting the demodulation order according to the magnitude of the SNR. The SNR is the ratio of the signal power to the noise power and is an important indicator for measuring signal quality. By dynamically adjusting the demodulation order, the signal component with the highest quality can be preferentially demodulated under different channel conditions, thereby reducing the bit error rate and improving the overall performance of the system.

[0053] Specifically, the logical judgment process includes the following steps: First, calculate the signal-to-noise ratios of the amplitude shift keying (ASK), phase shift keying (PSK), and pulse modulation (PULSE) components, denoted as SNR1, SNR2, and SNR3 respectively. The calculation of the SNR can be achieved by measuring the signal power and the noise power. For example, the power of the signal and the noise can be estimated through power spectral density analysis or autocorrelation function. Next, dynamically adjust the demodulation order according to the magnitude of the SNR. For example, when the SNR of all components is higher than the preset threshold, demodulation is performed in the order of ASK → PSK → PULSE; when the SNR is lower than the threshold, the component with the highest SNR is preferentially demodulated. In addition, when a time slot conflict of the pulse component is detected, start the time slot reallocation protocol to avoid mutual interference between signals. In this way, the system can flexibly adjust the demodulation strategy according to the channel conditions, thereby improving the adaptability and reliability of signal transmission.

[0054] Preferably, in order to further optimize the logical judgment process, more dynamic adjustment mechanisms can be introduced. For example, dynamically adjust the SNR threshold according to the real-time change of the channel so that it can better adapt to different channel environments. In the SNR calculation, a weighting factor can be introduced to weight the SNR according to the sensitivity of different modulation methods to the bit error rate, so as to more accurately reflect the signal quality.

[0055] Furthermore, for the time slot reallocation protocol, more intelligent algorithms can be adopted, such as priority-based time slot allocation or dynamic time slot adjustment algorithm, to improve the transmission efficiency and anti-interference ability of the pulse signal. Through these optimization measures, the logical judgment process can more flexibly adapt to complex channel conditions, thereby further improving the performance and reliability of the system.

[0056] The determination of the thresholds α and β is based on a comprehensive consideration of the evaluation of the channel noise level and the system performance requirements. For the threshold α, it is usually determined by statistically analyzing the signal-to-noise ratio (SNR) data under a large number of different channel conditions to find a critical value that can distinguish between relatively low and high channel noise levels. For example, when the SNR is lower than a certain value, the signal transmission quality will deteriorate significantly and the bit error rate will increase substantially. This critical value can be used as the threshold α. At the same time, it also needs to be adjusted according to the requirements of the system for signal transmission reliability and efficiency. If the system has extremely high requirements for reliability, α can be set to a relatively high value, such as around 0.7, to ensure that demodulation is performed in a fixed order only when the SNR is relatively high; while in a system with relatively high noise tolerance, α can be appropriately reduced to around 0.4. The determination of the threshold β is based on the impact of the SNR difference on demodulation, and the critical value at which the SNR difference begins to have a significant impact on the demodulation performance is found through simulation or experiment. When the SNR is lower than β, the demodulation of the component with the lowest SNR may be severely interfered, resulting in a substantial increase in the bit error rate and affecting the performance of the entire system. At this time, it is necessary to preferentially demodulate the component with the highest SNR. At the same time, combined with the system design goal, if the system aims to ensure the reliability of signal transmission as much as possible in a complex and changing channel environment, the value of β should be appropriately reduced so that the demodulation order can be adjusted in a timely manner when the SNR is relatively low. Generally, the value of β is less than α and is between 0 and 1. For example, it can be set to around 0.3. When the SNR is lower than 0.3, the system will preferentially demodulate the component with the highest SNR to improve the reliability of signal transmission.

[0057] In some embodiments, the dynamic adjustment of the modulation index includes: S91 Monitor the channel attenuation factor in real time ; S92 Update the modulation index according to the formula , where: : the channel attenuation factor, indicating the attenuation degree of the channel to the signal; : the reference attenuation value, used to normalize the channel attenuation; S93 When , switch to the fixed-amplitude modulation mode.

[0058] It should be noted that the dynamic adjustment of the modulation index is an important step in amplitude-shift keying (ASK) modulation for optimizing signal transmission performance. The modulation index is a key parameter that determines the amplitude change of the signal, thus affecting the anti-interference ability and transmission efficiency of the signal. By monitoring the channel attenuation factor in real time and dynamically adjusting the modulation index according to the channel state, the signal transmission performance can be optimized under different channel conditions. The channel attenuation factor is a parameter that characterizes the attenuation degree of the channel to the signal and is usually used to quantify the energy loss of the signal during transmission.

[0059] Specifically, the dynamic adjustment process of the modulation index includes the following steps: First, the channel attenuation factor is monitored in real time, which can be achieved by measuring the ratio of the power of the received signal to the power of the transmitted signal. Subsequently, according to the formula the modulation index is updated. When the channel attenuation is small, the modulation index increases, thereby increasing the amplitude change range of the signal and enhancing the anti-interference ability of the signal; when the channel attenuation is large, the modulation index decreases to avoid signal distortion due to overmodulation. In addition, when the modulation index is less than a certain threshold (e.g., 0.2), the system can switch to the fixed amplitude modulation mode to further improve the signal stability.

[0060] Preferably, in order to further optimize the dynamic adjustment process of the modulation index, more adaptive mechanisms can be introduced. For example, the reference attenuation value can be dynamically adjusted according to the time-varying characteristics of the channel so that it can better reflect the actual state of the channel. In addition, an adaptive filter or a machine learning algorithm can be introduced to more accurately predict the channel attenuation factor thereby improving the real-time performance and accuracy of the modulation index adjustment.

[0061] Furthermore, in practical applications, different modulation index thresholds can also be set according to different application scenarios. For example, in the high-speed mobile communication scenario, the threshold for switching to the fixed amplitude modulation mode can be appropriately increased to adapt to the rapidly changing channel environment. Through these optimization measures, the dynamic adjustment of the modulation index can more flexibly adapt to complex channel conditions, thereby improving the reliability and efficiency of signal transmission.

[0062] In some embodiments, the optimization of the phase difference factor includes: S101 Statistics of the phase jump amount of consecutive symbols, where: : the phase jump of the th symbol; : the phase of the th symbol; : the phase of the th symbol; S102 Calculate the phase jump variance where represents the variance of the phase jump; S103 Update the phase difference factor according to the formula where: : the updated phase difference factor; : the current phase difference factor;

[0063] It should be noted that the optimization of the phase difference factor is an important step in phase shift keying (PSK) modulation for improving signal transmission performance. The phase difference factor is a key parameter that determines the phase difference between adjacent symbols, thus affecting the anti-interference ability and transmission efficiency of the signal. By statistically analyzing the phase jump amount and calculating its variance, the phase difference factor can be dynamically adjusted to adapt to different channel conditions and optimize signal transmission performance. The phase jump amount refers to the change in phase between adjacent symbols, and the variance is used to quantify the dispersion degree of these jumps, thereby providing a basis for adjusting the phase difference factor.

[0064] Specifically, the optimization process of the phase difference factor includes the following steps: First, statistically analyze the phase jump amount of consecutive symbols, where is the phase of the i-th symbol. Then, calculate the variance of these phase jump amounts. The magnitude of the variance reflects the stability of the phase jumps. Update the phase difference factor according to the formula , where is the target variance value, which is used as a benchmark for adjusting the phase difference factor. When the variance deviates from the target variance , the phase difference factor will be adjusted accordingly, thereby optimizing the anti-interference ability of the signal. For example, when the variance is large, increase the phase difference factor to improve the phase discrimination; when the variance is small, reduce the phase difference factor to avoid unnecessary phase changes.

[0065] Preferably, in order to further optimize the adjustment process of the phase difference factor, more adaptive mechanisms can be introduced. For example, the target variance can be dynamically adjusted according to the dynamic characteristics of the channel, so that it can better reflect the actual state of the channel. In addition, an adaptive filter or machine learning algorithm can be introduced to more accurately predict the phase jump amount, thereby improving the real-time performance and accuracy of the phase difference factor adjustment. In practical applications, different phase difference factor adjustment coefficients (such as 0.1) can also be set according to different application scenarios. For example, in a high-noise environment, the adjustment coefficient can be appropriately increased to enhance the anti-interference ability of the signal; in a low-noise environment, the adjustment coefficient can be reduced to improve the transmission efficiency of the signal. Through these optimization measures, the dynamic adjustment of the phase difference factor can more flexibly adapt to complex channel conditions, thereby improving the reliability and efficiency of signal transmission.

[0066] The above embodiments of the present invention have the following beneficial effects: The present invention provides an efficient, flexible and highly adaptable composite signal modulation and demodulation method. By splitting the input signal into multiple sub-signal sequences and using different modulation methods respectively, it is possible to make full use of the advantages of amplitude shift keying (ASK), phase shift keying (PSK) and pulse feature modulation, realize the organic combination of frequency division multiplexing and time division multiplexing, and thus significantly improve the signal transmission efficiency and anti-interference ability. At the same time, this method can dynamically adjust the demodulation order and modulation parameters, such as modulation index and phase difference factor, according to the channel noise level, further optimizing the signal transmission performance and ensuring high-reliability communication under complex channel conditions. In addition, by adding cyclic redundancy check coding and synchronization header identifiers, the error correction ability and synchronization performance of the signal can be effectively enhanced, further improving the stability and reliability of the system.

[0067] Through signal decomposition techniques such as frequency band separation, time slot detection and integration decision, each modulation component can be accurately extracted, further improving the demodulation accuracy. At the same time, the dynamic adjustment mechanism of modulation parameters, such as updating the modulation index in real time according to channel attenuation and optimizing the phase difference factor according to the phase jump variance, enables the system to adaptively cope with channel changes, improving the flexibility and robustness of signal transmission. The comprehensive application of these technologies can not only improve the signal transmission efficiency, but also enhance the adaptability of the system in complex environments, providing an efficient and reliable solution for modern communication systems.

[0068] Furthermore, the storage medium of the embodiment of the present application stores program instructions capable of implementing all the above methods. Among them, the program instructions can be stored in the above storage medium in the form of a software product, including several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods described in various embodiments of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks or optical discs, or terminal devices such as computers, servers, mobile phones, and tablets.

[0069] The above description is only some preferred embodiments of the present invention and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present invention is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the embodiments of the present invention.

Claims

1. A method for modulating and demodulating a composite signal, characterized in that It includes the following steps: Divide the input digital signal sequence into a first sub-signal sequence, a second sub-signal sequence, and a third sub-signal sequence; Perform amplitude shift keying modulation on the first sub-signal sequence to generate a first modulation signal, perform phase shift keying modulation on the second sub-signal sequence to generate a second modulation signal, and perform pulse feature modulation on the third sub-signal sequence to generate a third modulation signal; Combine the first modulation signal, the second modulation signal, and the third modulation signal through frequency division multiplexing and time division multiplexing to generate a composite carrier signal; Amplify the power and perform radio frequency processing on the composite carrier signal through a transmitter; The receiver performs low-noise amplification and down-conversion processing on the received composite carrier signal; Extract a first demodulation component, a second demodulation component, and a third demodulation component from the processed composite carrier signal through a digital filter and a time domain separation algorithm; Perform amplitude decision demodulation on the first demodulation component respectively, perform phase difference demodulation on the second demodulation component, and perform pulse feature recognition demodulation on the third demodulation component; Dynamically adjust the execution order of the amplitude decision demodulation, phase difference demodulation, and pulse feature recognition demodulation according to the channel noise level; Recombine the three demodulated sub-signal sequences into the original digital signal sequence according to a preset rule.

2. The method according to claim 1, wherein The step of dividing the input digital signal sequence into a first sub-signal sequence, a second sub-signal sequence, and a third sub-signal sequence includes: Divide the input digital signal sequence into three consecutive signal segments according to a preset ratio; Perform cyclic redundancy check encoding on each signal segment to generate a check code; Add a synchronization header identifier at the head of each signal segment; Define the three signal segments with the synchronization header added as the first sub-signal sequence, the second sub-signal sequence, and the third sub-signal sequence respectively.

3. The method according to claim 1, characterized in that The step of performing amplitude shift keying modulation on the first sub-signal sequence to generate a first modulation signal includes: Set the reference amplitude and the modulation index ; Establish an amplitude mapping function , where is the modulation amplitude of the th symbol; is the reference amplitude; is the modulation index, representing the amplitude change range; is the value of the th symbol in the first sub-signal sequence; Generate a modulation waveform according to the formula: , , where is an amplitude shift keying modulation signal; is the carrier frequency; is the symbol period; is the time variable.

4. The method according to claim 1, wherein The step of performing phase shift keying modulation on the second sub-signal sequence to generate a second modulation signal includes: Set the phase difference factor ; Establish a phase recurrence formula , where is the phase of the -th symbol; is the phase difference factor, representing the phase difference between adjacent symbols; is the value of the -th symbol in the second sub-signal sequence; Generate a modulation waveform according to the following formula: , , where is a phase - keyed modulation signal; is the carrier frequency; is the symbol period; is the time variable.

5. The method according to claim 1, wherein The step of performing pulse feature modulation on the third sub-signal sequence to generate a third modulation signal includes: Set the reference pulse width and the pulse interval ; Establish a calculation formula for pulse parameters: pulse width , where is the actual width of the th pulse; is the reference pulse width; is the value of the th symbol in the third sub-signal sequence; Calculate the pulse interval according to the following formula: , where is the actual interval of the th pulse; is the reference pulse interval; Generate a modulation waveform according to the following formula: , where is a pulse modulation signal; is the Dirac function, representing the starting point of the pulse; is a rectangular pulse function, representing the shape of the pulse; is the starting time of the th pulse.

6. The method according to claim 1, characterized in that, The step of combining the first modulation signal, the second modulation signal, and the third modulation signal through frequency division multiplexing and time division multiplexing to generate a composite carrier signal includes: Allocate a frequency band segment to the first modulation signal , allocate a frequency band to the second modulation signal , allocate a time slot to the third modulation signal , where is the starting frequency of the first and second modulation signals; is the frequency band width; is the starting time of the time slot; is the time slot index; is the pulse interval; Perform orthogonal frequency division multiplexing on the first and second modulation signals in the frequency domain; Perform time division multiplexing on the third modulation signal in the time domain; Generate a composite carrier signal through the following formula: wherein is the composite carrier signal; are amplitude shift keying, phase shift keying, and pulse modulation signals respectively.

7. The method according to claim 1, wherein The step of extracting a first demodulation component, a second demodulation component, and a third demodulation component from the processed composite carrier signal through a digital filter and a time domain separation algorithm includes: Use a matching filter bank to separate the frequency bands of the composite signal and extract the ASK frequency band component and the PSK frequency band component; Use a time slot detection algorithm to identify the time domain position of the pulse signal; Perform envelope detection on the ASK component to obtain the first demodulation component; Perform coherent demodulation on the PSK component to obtain the second demodulation component; Perform integral decision on the pulse component to obtain the third demodulation component.

8. The method according to claim 1, wherein The step of dynamically adjusting the execution order of the amplitude decision demodulation, phase difference demodulation, and pulse feature recognition demodulation according to the channel noise level includes: Calculate the signal-to-noise ratio of each component , , , corresponding to the signal-to-noise ratios of the ASK, PSK, and PULSE components respectively; When threshold is reached, demodulation is performed in the order of ASK, PSK, and PULSE in sequence; When demodulate the component with the highest signal-to-noise ratio preferentially; When detecting a time slot conflict of the pulse component, start the time slot reallocation protocol.

9. The method according to claim 3, wherein The modulation index The dynamic adjustment includes: Real-time monitoring of the channel attenuation factor ; Update the modulation index according to the following formula; ; Among them, is the channel attenuation factor; is the reference attenuation value; When switch to the fixed amplitude modulation mode.

10. The method according to claim 4, characterized in that The phase difference factor is optimized as follows: Count the phase jump variables of the following symbols according to the following formula; ； Among them, is the phase jump of the th symbol; is the phase of the th symbol; Calculate the phase jump variance according to the following formula; , where is the variance of the phase jump; Update the phase difference factor according to the following formula, ； Among them, is the updated phase difference factor; is the current phase difference factor; is the target variance value.

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