A camouflage covert communication method and device based on time-frequency profile curve

Abstract

This invention discloses a camouflage and covert communication method and apparatus based on time-frequency profile curves, comprising: collecting real vocal samples of biomimetic objects; performing endpoint detection based on the short-time energy principle to extract time-domain vocal pulse signals; obtaining time-frequency profile curves and performing smoothing operations; and calculating the maximum slope k of the time-frequency profile curves corresponding to each time-domain vocal pulse signal. max The method involves determining the number of extreme points (n) and grouping all time-domain vocal pulse signals into hierarchical groups. The pulse group number to be encoded is determined based on the communication information to be transmitted. The determined pulse group number is then used to encode the communication information into a communication pulse sequence. This sequence is transmitted through a transducer, and the receiving device filters and decodes the received signal to obtain the complete communication information. This method utilizes animal vocalizations from nature as a communication carrier, improving both communication security and speed.

Description

Technical Field

[0001] This invention relates to the field of acoustic wireless communication, particularly to scenarios where high levels of communication concealment are required. It is a method for high-speed biomimetic camouflage and covert communication by encoding communication information using the maximum slope and number of poles of the time-frequency profile curve of animal vocalization pulses. Background Technology

[0002] Acoustic camouflage and covert communication technology is a covert information transmission technology based on acoustic channels. It uses sound waves as carrier waves for data transmission, offering excellent concealment. Sound waves are mechanical waves, possessing different characteristics from radio waves, which are electromagnetic waves. Compared to radio communication, acoustic communication is simpler to operate and more difficult to shield. Given the availability of mature electromagnetic shielding and interference technologies, acoustic communication has become an important communication tool in military, intelligence, and other fields.

[0003] Nature abounds with small, geographically widespread animals that prefer solitary or paired activity and possess loud, varied calls. Current methods for camouflage and covert communication in the air involve creating a camouflage database by identifying templates from common animal calls. This allows the modulated signal carrying communication information to closely match the surrounding environment, ensuring that even if intercepted, the signal is mistaken for a common animal call and filtered out. Enemy forces can only effectively interfere by continuously transmitting high-power, wide-bandwidth jamming sound waves, but this easily exposes the jammer's location and could cause temporary or permanent hearing damage to all people and animals in the interference environment, making the cost of interference prohibitively high. Based on time-frequency analysis of the pulses of biomimetic animal call syllables, selecting appropriate time-frequency characteristics to describe and quantify these pulses is a crucial foundation for achieving biomimetic camouflage and covert communication. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a biomimetic camouflage and covert communication encoding and decoding method and device that uses the maximum slope and the number of extreme points of the time-frequency profile curve of animal vocalization pulses as features.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A camouflage and covert communication method based on time-frequency profile curves includes:

[0007] S1. The time-domain vocal pulse signal of the biomimetic object is converted to the time-frequency domain using a short-time Fourier transform, and the time-frequency profile curve is obtained. The mathematical expression of the short-time Fourier transform of the time-domain vocal pulse signal is as follows:

[0008]

[0009] In equation (1), t is time, f is frequency, j is imaginary unit, τ is time delay, h(τ-t) is the window function for short-time Fourier transform, usually a Hamming window, and x(t) is the time-domain acoustic pulse signal to be transformed.

[0010] S2. Based on the continuity characteristics of the time-frequency profile curve, outliers in the time-frequency profile curve are removed to obtain a smooth time-frequency profile curve.

[0011] S3. Calculate the maximum slope k of the time-frequency profile curve corresponding to each time-domain acoustic pulse signal. max The number of extreme points, n, is determined, and all time-domain vocal pulse signals are hierarchically grouped; considering the communication rate requirements and the characteristics of the biomimetic object's real vocal pulse sequence, based on the maximum slope k... max All time-domain acoustic pulse signals are divided into m1 groups. Based on the number of extreme points n, all time-domain acoustic pulse signals are divided into m2 groups. Therefore, all time-domain acoustic pulse signals are further divided into 2 groups. m Group 2 completed the construction of the communication pulse library, of which 2 m = m1 * m2, where m is the number of bits in the encoding of each time-domain acoustic pulse signal, and the number of pulses in the communication pulse library should be greater than 2. m ;

[0012] S4. Determine the corresponding pulse group number based on the communication information to be sent;

[0013] S5. Encode the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence;

[0014] S6. The transducer transmits a pre-coded communication pulse sequence. The receiving device receives the corresponding communication signal, performs filtering, and then decodes the communication signal to obtain the complete communication information.

[0015] Furthermore, step S4 is detailed as follows:

[0016] S401. First, divide the communication information to be sent into blocks of m bits each;

[0017] S402. Calculate the group number G of the time-domain acoustic pulse signal corresponding to each block of communication information to be sent; G is the decimal number corresponding to the m-bit binary number of each group of communication information to be sent.

[0018] Furthermore, step S5 is detailed as follows:

[0019] S501. For a given communication frame, insert a quantity indicator code CNI as the frame header of the communication frame; to ensure concealment, ensure that the number of information codes in each communication frame conforms to the statistical law of the real vocal pulse sequence of the bionic object; the quantity indicator code is randomly selected from the communication pulse library, and a mapping relationship between the number of information codes in the communication frame indicated by the quantity indicator code and the group number to which the quantity indicator code belongs is established according to the statistical law.

[0020] S502. Every time interval τ, take m bits from the communication information to be sent to determine the group number of the time-domain vocal pulse signal to be inserted, and randomly select a time-domain vocal pulse signal from the corresponding group as the communication signal, until the number of time-domain vocal pulse signals in the corresponding communication frame reaches the specified value of the quantity indicator code, thus completing the encoding of one frame of communication signal; τ is the time interval between different time-domain vocal pulse signals, which conforms to the statistical law of the real vocal pulse sequence of the bionic object;

[0021] S503. After a time interval τ p Then, a quantity indicator code is inserted as the frame header of a new communication signal frame. The communication information to be sent is then encoded according to the encoding rules of step S502. This process is repeated until all communication information to be sent has been encoded, resulting in a communication pulse sequence; τ p The time interval between different communication frames conforms to the statistical regularity of the real vocal pulse sequence of the biomimetic object.

[0022] Furthermore, a communication frame includes a quantity indicator code and several information codes, each of which is a time-domain vocal pulse signal.

[0023] Furthermore, step S6 is as follows:

[0024] S601. Use spectral subtraction and bandpass filter to filter out environmental noise introduced into the communication signal received by the receiving device during transmission;

[0025] S602. Calculate the short-time energy spectrum E of the communication signal, defining the short-time energy of the communication signal at time T as:

[0026]

[0027] In the formula, x(k) is the communication signal, k is the sampling point, win is the frame length, and inc is the frame shift;

[0028] S603 filters out vocal pulses in communication signals based on the energy intensity characteristics of the communication signals; it sets an energy threshold ET, and when the short-term energy of the communication signal is higher than ET, this part of the communication signal is used as a vocal pulse;

[0029] S604. Calculate the time interval between each cry pulse in the communication signal sequentially. Based on the fact that the time interval τ between adjacent time-domain cry pulse signals within each communication frame is less than the time interval τ between different communication frames... p To distinguish between information codes and quantity indicator codes;

[0030] S605. Decode each frame sequentially; extract the time-frequency profile curve of each time-domain acoustic pulse signal, and calculate the maximum slope k of its time-frequency profile curve. max The number of extreme points, n, determines the group number to which the corresponding time-domain acoustic pulse signal belongs;

[0031] S606. For quantity indicator codes, determine the number of information codes in the corresponding communication frame according to their group number; for information codes, determine the m-bit binary information they represent according to their group number; repeat the above steps until all communication signals are decoded, and finally obtain complete communication information.

[0032] The present invention also provides a camouflage and covert communication device based on time-frequency profile curves, comprising:

[0033] The extraction unit is used to collect real vocal samples of biomimetic objects, and extracts time-domain vocal pulse signals based on the short-time energy principle to achieve endpoint detection.

[0034] The time-frequency profile curve construction unit is used to convert the extracted time-domain cry pulse signal to the time-frequency domain through short-time Fourier transform and obtain the time-frequency profile curve; and to remove outliers in the time-frequency profile curve based on the continuity characteristics of the time-frequency profile curve to obtain a smooth time-frequency profile curve.

[0035] The calculation unit is used to calculate the maximum slope k of the time-frequency profile curve. max The number of extreme points, n, is used as the first and second levels of hierarchical grouping of the time-domain vocal pulse signal;

[0036] The communication pulse library construction unit is used to combine the requirements of communication rate with the characteristics of the real vocal pulse sequence of the biomimetic object, based on the maximum slope k. max All time-domain acoustic pulse signals are divided into m1 groups. Based on the number of extreme points n, all time-domain acoustic pulse signals are divided into m2 groups. Therefore, all time-domain acoustic pulse signals are further divided into 2 groups. m Group 2 completed the construction of the communication pulse library, of which 2 m = m1 * m2, where m is the number of bits in the encoding of each time-domain acoustic pulse signal, and the number of pulses in the communication pulse library should be greater than 2. m ;

[0037] The numbering unit is used to determine the pulse group number to be encoded based on the communication information to be transmitted;

[0038] The encoding unit is used to encode the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence;

[0039] The transmitting unit is used to transmit a pre-coded communication pulse sequence to the outside world through a transducer;

[0040] The filtering unit is used to receive the corresponding communication signals and perform filtering processing.

[0041] The decoding unit is used to decode the communication signal after it has been processed by the filtering unit to obtain complete communication information.

[0042] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the camouflage and covert communication method based on time-frequency profile curves.

[0043] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the camouflage and covert communication method based on time-frequency profile curves.

[0044] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0045] 1. High-efficiency encoding and decoding: Using unprocessed raw animal vocalizations as communication signals eliminates the need for complex calculations and processing, greatly reducing the computational load of encoding and decoding and improving communication speed and reliability.

[0046] 2. High degree of concealment: Utilizing the calls of animals widely distributed in nature as a communication carrier makes the communication signals difficult to detect and decipher within the monitored range, thus improving the security of communication.

[0047] 3. Long-distance transmission: Compared with other sound wave communication methods such as ultrasound, this technology uses a lower sound frequency and less attenuation, which can achieve a longer communication distance.

[0048] 4. Strong anti-interference capability: There is no mature acoustic interference technology for this communication method in the existing technology, which makes this technology have strong anti-interference capability and difficult to be interfered with or shielded.

[0049] 5. Scalability: This technology is not limited to individual biomimetic objects. Different animal sounds can be selected as communication carriers according to actual needs. It can also be combined with other feature encoding technologies to achieve better results in different scenarios.

[0050] 6. High adaptability: This technology is applicable to various environmental conditions, such as cities, forests, and deserts, and has strong adaptability.

[0051] 7. Easy to implement: This technology requires no additional equipment or technical support. It can achieve covert communication by simply modifying existing communication equipment, and has low requirements for hardware platform performance.

[0052] 8. Environmentally friendly and pollution-free: This technology uses animal sounds as a communication carrier, which will not produce electromagnetic radiation or other pollution, and has a small impact on the environment and ecology. Attached Figure Description

[0053] Figure 1 This is a flowchart illustrating the method of the present invention.

[0054] Figure 2a This is a pulse time-frequency diagram of the call of the Copper Blue Flycatcher. Figure 2b The waveform of the call pulse of the Copper Blue Flycatcher in the time domain. Figure 2c This is a time-domain waveform of a single copper blue croaking sound pulse extracted using short-time energy. Figure 2d This is a schematic diagram showing the maximum slope and the number of extreme points of the time-frequency profile curve. Figure 2d In the curve, 1 represents the maximum slope of the time-frequency profile curve, and 2 represents the extreme point in the time-frequency profile curve.

[0055] Figures 3a to 3d The time-frequency profile curves of four different call pulses of the Copper Blue Flycatcher are shown, along with the communication information represented at m=4. Figure 3a The pulse group shown is 2, and the encoded information is "0001"; Figure 3b The pulse group shown is 14, and the encoding information is "1101"; Figure 3c The pulse group shown is 1, and the encoded information is "0000"; Figure 3d The pulse group shown is 6, and the encoded information is "0101".

[0056] Figure 4 This diagram illustrates a tree-structured pulse hierarchical grouping model based on time-frequency profile curves proposed in this invention.

[0057] Figure 5a and Figure 5b The present invention illustrates the biomimetic camouflage and covert communication frame structure. Figure 5a 3 is the time-domain waveform of the communication signal, 4 is the quantity indicator code, 5 is the information code, 6 is the time interval between adjacent information codes, and 7 is the interval between two communication frames. Figure 5b This is the time-frequency profile curve of the communication pulse extracted by STFT. Detailed Implementation

[0058] This invention utilizes animal vocalization pulses as communication carriers and designs a novel biomimetic camouflage and concealment communication encoding / decoding method and communication frame structure based on the time-frequency profile curve characteristics of the vocalization pulses. This method hides communication information within animal vocalizations, achieving camouflage and concealment communication. Specifically, this embodiment uses the copper-blue flycatcher as the biomimetic object and, in conjunction with the accompanying drawings, further illustrates this invention.

[0059] The time-frequency diagram and time-domain waveform of the call pulse of the Copper Blue Flycatcher are as follows: Figure 2a and Figure 2b As shown, the average frequency of the call of the Copper-blue Flycatcher is 4.41 kHz, with a frequency range of 3 kHz to 6 kHz. The frequency is relatively low and occupies a narrow bandwidth. The call consists of multiple syllable pulses, with individual pulse lengths ranging from 40 ms to 210 ms. The silence interval between adjacent pulses ranges from 15 ms to 60 ms, and 19 to 26 pulses form a pulse segment. The silence interval between pulse segments is approximately 3 to 7 seconds. This embodiment starts with the time-frequency profile of the Copper-blue Flycatcher's call pulses and uses the short-time energy principle to achieve endpoint detection and extract the time-domain waveform of a single Copper-blue Flycatcher's call pulse. (See the image below.) Figure 2c The extracted time-domain vocal pulse signal was converted to the time-frequency domain using a short-time Fourier transform, and the maximum slope 1 and the number of extreme points 2 of the time-frequency profile curve for each syllable were obtained. (See...) Figure 2d ;

[0060] The time-frequency profile curves of four typical copper blue flycatcher call pulses are as follows: Figures 3a to 3d As shown, the maximum slope and the number of extreme points of different pulse time-frequency profile curves vary greatly, which can be used as features to encode communication information.

[0061] A communication frame is the smallest unit carrying information in a communication signal. Therefore, this embodiment designs a signal frame structure based on the communication frame to mimic the camouflage and concealment of a copper-blue flycatcher's call. Each communication frame is disguised as a pulse segment of a copper-blue flycatcher's call. The frame structure of the communication signal is as follows: Figure 5a and Figure 5b As shown. The actual call of the Copper Blue Flycatcher contains multiple sound segments. In this embodiment, each sound segment is treated as a communication frame, with a certain duration of silence between communication frames. A communication frame includes one quantity indicator code 3 and several information codes 4. Using the quantity indicator code facilitates the determination of the length of the current communication frame at the receiving end and improves decoding accuracy. Since the number of call pulses in each segment of the actual call of the Copper Blue Flycatcher is distributed between 19 and 26, and there is no obvious pattern, the number of information codes in each frame signal can be flexibly selected within this range according to the length of the information to be sent to ensure communication concealment. The quantity indicator code and information codes used are all Copper Blue Flycatcher call pulses that have not undergone any processing.

[0062] For details, see Figure 1The steps for achieving covert communication based on the call pulse signal of the Copper Blue Flycatcher in this implementation are as follows:

[0063] First, we collected real calls of the Copper Blue Flycatcher and extracted a series of real time-domain call pulse signals of the Copper Blue Flycatcher based on endpoint detection using short-time energy.

[0064] Furthermore, the time-frequency profile curves of each time-domain cry pulse signal are extracted using STFT, and outliers in the curves are removed based on the continuity characteristics of the time-frequency profile curves.

[0065] Furthermore, by analyzing the time-frequency profile curves of each time-domain cry pulse signal, the maximum slope and the number of extreme points of each time-domain cry pulse signal are determined. Then, all pulses are grouped into hierarchical levels based on these two characteristics. For example... Figure 4 As shown: All pulses are divided into 4 groups according to the maximum slope of the time-frequency profile curve (0-50Hz / ms, 70Hz / ms-120Hz / ms, 150Hz / ms-200Hz / ms, 250Hz / ms-400Hz / ms). These 4 groups are then further divided into 4 subgroups based on the number of extreme points in the time-frequency profile curve (1-3, 4-6, 7-9, 10-13). This results in a total of 16 groups of real copper-blue flycatcher time-domain call pulse signals. Any time-domain call pulse signal within each group is encoded with the same information to ensure communication concealment. The maximum slope and number of extreme points of the pulse time-frequency profile curve in each group differ from other groups, and there is sufficient detection margin.

[0066] Furthermore, the pulse group number to be encoded is determined based on the communication information to be transmitted. First, the communication information is divided into blocks of m = 4 bits each. For example, assuming the communication information to be transmitted is "00011101...", the communication information is divided into blocks B1: "0001", B2: "1101", ...

[0067] Next, calculate the group number G corresponding to the pulse of each block of communication information to be transmitted. G is the decimal number corresponding to the m-bit binary number of each group of information. For example, the G corresponding to each block of information in the previous step are: G1 = 2, G2 = 14, ...

[0068] Furthermore, a quantity indicator code is inserted as the frame header. The quantity indicator code is randomly selected from the communication pulse library. If the group number of the quantity indicator code is i, then the quantity it indicates is 19 + [i*0.5], so as to ensure that the number of call pulses in each communication frame of the communication pulse sequence is distributed between 19 and 26, which conforms to the rule that the number of call pulses contained in each segment of the real call of the Copper Blue Flycatcher is distributed between 19 and 26, thus enhancing the concealment. [] indicates rounding.

[0069] Furthermore, every time interval τ, 4 bits are taken from the communication information to be sent to obtain the corresponding group number, and a time-domain call pulse signal is randomly selected from the group as the communication signal. This process continues until the number of time-domain call pulse signals reaches the specified value of the quantity indicator code, thus completing the encoding of one frame of communication signal. The value of τ is randomly selected between 15ms and 60ms.

[0070] Furthermore, after each frame is encoded, time τ is elapsed. p A quantity indicator code is then inserted as the frame header of the new communication signal, τ. p The value is randomly selected between 3s and 7s, and the encoding rules of the previous step are used to continue encoding the communication information to be sent. This process is repeated until all the communication information to be sent has been encoded, resulting in a communication pulse sequence.

[0071] After encoding is completed, a communication signal is transmitted outward through the transducer. Upon receiving the communication signal, the receiving device begins decoding. The specific decoding steps are as follows:

[0072] First, the received communication signal is filtered, and environmental noise introduced during transmission is removed by using spectral subtraction and bandpass filtering.

[0073] Furthermore, the short-time energy spectrum of the communication signal is calculated, and the vocal pulses in the communication signal are screened out based on the short-time energy characteristics of the communication signal.

[0074] Furthermore, the time intervals in the communication signal are calculated sequentially, based on the fact that the interval τ between adjacent time-domain acoustic pulse signals within a frame is less than the time interval τ between different communication frames. p One-tenth of the code is used to distinguish between the information code and the quantity indicator code.

[0075] Furthermore, each frame is decoded sequentially. The time-frequency profile curves of each time-domain cryo pulse signal are extracted, and the maximum slope k of the time-frequency profile curves is calculated. max The number of extreme points, n, is used to determine the group number to which the time-domain acoustic pulse signal belongs. For the quantity indicator code, the number of information codes in the communication frame is determined based on its group number. For the information code, the 4-bit binary information it represents is determined based on its group number. The above steps are repeated until all communication signals are decoded, and finally, complete communication information is obtained.

[0076] Based on the same inventive concept, this application also provides a covert communication device based on time-frequency profile curves, which can be used to implement the method described in the above embodiments, as described in the following embodiments. Since the principle of the covert communication device based on time-frequency profile curves is similar to that of the covert communication method based on time-frequency profile curves, the implementation of the covert communication device based on time-frequency profile curves can refer to the implementation of the covert communication method based on time-frequency profile curves, and repeated details will not be elaborated further. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the system described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0077] The camouflage and covert communication device based on time-frequency profile curves specifically includes the following:

[0078] The extraction unit is used to collect real vocal samples of biomimetic objects, and extracts time-domain vocal pulse signals based on the short-time energy principle to achieve endpoint detection.

[0079] The time-frequency profile curve construction unit is used to convert the extracted time-domain cry pulse signal to the time-frequency domain through short-time Fourier transform and obtain the time-frequency profile curve; and to remove outliers in the time-frequency profile curve based on the continuity characteristics of the time-frequency profile curve to obtain a smooth time-frequency profile curve.

[0080] The calculation unit is used to calculate the maximum slope k of the time-frequency profile curve. max The number of extreme points, n, is used as the first and second levels of hierarchical grouping of the time-domain vocal pulse signal;

[0081] The communication pulse library construction unit is used to combine the requirements of communication rate with the characteristics of the real vocal pulse sequence of the biomimetic object, based on the maximum slope k. max All time-domain acoustic pulse signals are divided into m1 groups. Based on the number of extreme points n, all time-domain acoustic pulse signals are divided into m2 groups. Therefore, all time-domain acoustic pulse signals are further divided into 2 groups. m Group 2 completed the construction of the communication pulse library, of which 2 m = m1 * m2, where m is the number of bits in the encoding of each time-domain acoustic pulse signal, and the number of pulses in the communication pulse library should be greater than 2. m ;

[0082] The numbering unit is used to determine the pulse group number to be encoded based on the communication information to be transmitted;

[0083] The encoding unit is used to encode the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence;

[0084] The decoding unit is used to transmit an encoded communication pulse sequence through a transducer. After receiving the corresponding communication signal, the receiving device filters it and then decodes the communication signal to obtain the complete communication information.

[0085] As described above, the camouflage and covert communication device based on time-frequency profile curves provided in this invention enables the use of unprocessed raw animal vocalizations as communication signals. This eliminates the need for complex calculations and processing, significantly reducing the computational load of encoding and decoding, and improving communication speed and reliability. Utilizing widely distributed animal vocalizations in nature as a communication carrier makes the communication signals difficult to detect and decipher within the monitored range, thus enhancing communication security.

[0086] Preferably, embodiments of this application also provide a specific implementation of an electronic device capable of implementing all steps of the camouflage and covert communication method based on time-frequency profile curves in the above embodiments. The electronic device specifically includes the following:

[0087] Processor, memory, communications interface, and bus;

[0088] The processor, memory, and communication interface communicate with each other via a bus; the communication interface is used to realize information transmission between server-side devices, metering devices, and user-side devices.

[0089] The processor is used to call the computer program in the memory. When the processor executes the computer program, it implements all the steps in the camouflage and covert communication method based on time-frequency profile curves in the above embodiments.

[0090] Embodiments of this application also provide a computer-readable storage medium capable of implementing all steps of the camouflage and covert communication method based on time-frequency profile curves in the above embodiments. The computer-readable storage medium stores a computer program that, when executed by a processor, implements all steps of the camouflage and covert communication method based on time-frequency profile curves in the above embodiments.

[0091] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0092] While this application provides method operation steps as shown in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive labor. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only execution order. In actual device or client product execution, the method can be executed sequentially as shown in the embodiments or drawings, or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0093] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0095] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0096] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A camouflage and covert communication method based on time-frequency profile curves, characterized in that, include: S1. The time-domain vocal pulse signal of the biomimetic object is converted to the time-frequency domain using a short-time Fourier transform, and the time-frequency profile curve is obtained. The mathematical expression of the short-time Fourier transform of the time-domain vocal pulse signal is as follows: ； In formula (1) For time, For frequency, The imaginary unit, For time delay, The window function for performing the short-time Fourier transform. The time-domain signal to be transformed is called the acoustic pulse signal; S2. Based on the continuity characteristics of the time-frequency profile curve, outliers in the time-frequency profile curve are removed to obtain a smooth time-frequency profile curve. S3. Calculate the maximum slope of the time-frequency profile curve corresponding to each time-domain acoustic pulse signal. and the number of extreme points Furthermore, all time-domain vocal pulse signals are hierarchically grouped; considering the communication rate requirements and the characteristics of the biomimetic object's real vocal pulse sequence, based on the maximum slope... Divide all time-domain acoustic pulse signals into Groups, based on the number of extreme points Divide all time-domain acoustic pulse signals into Groups are used to divide all time-domain acoustic pulse signals into groups. The group completed the construction of the communication pulse library, among which... , The number of bits used to encode each time-domain acoustic pulse signal should be greater than the number of pulses in the communication pulse library. ; S4. Determine the corresponding pulse group number based on the communication information to be sent; S5. Encode the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence; S6. The transducer transmits a pre-coded communication pulse sequence. The receiving device receives the corresponding communication signal, performs filtering, and then decodes the communication signal to obtain the complete communication information.

2. The camouflage and covert communication method based on time-frequency profile curves according to claim 1, characterized in that, Step S4 is as follows: S401. First, divide the communication information to be sent into blocks of m bits each; S402. Calculate the group number G of the time-domain acoustic pulse signal corresponding to each block of communication information to be transmitted; G is the group number of each block of communication information to be transmitted. The decimal number corresponding to a binary number.

3. The camouflage and covert communication method based on time-frequency profile curves according to claim 1, characterized in that, Step S5 is as follows: S501. For a given communication frame, insert a quantity indicator code CNI as the frame header of the communication frame; to ensure concealment, ensure that the number of information codes in each communication frame conforms to the statistical law of the real vocal pulse sequence of the bionic object; the quantity indicator code is randomly selected from the communication pulse library, and a mapping relationship between the number of information codes in the communication frame indicated by the quantity indicator code and the group number to which the quantity indicator code belongs is established according to the statistical law. S502. Every time interval Take m bits from the communication information to be sent to determine the group number of the time-domain call pulse signal to be inserted, and randomly select a time-domain call pulse signal from the corresponding group as the communication signal. Continue until the number of time-domain call pulse signals in the corresponding communication frame reaches the specified value of the quantity indicator code, and complete the encoding of a frame of communication signal. The time interval between vocal pulse signals in different time domains conforms to the statistical regularity of the real vocal pulse sequence of the biomimetic object; S503. After a time interval Then, a quantity indicator code is inserted as the frame header of a new communication signal. Then, the communication information to be sent is encoded according to the encoding rules in step S502. This process is repeated until all the communication information to be sent is encoded, resulting in a communication pulse sequence. The time interval between different communication frames conforms to the statistical regularity of the real vocal pulse sequence of the biomimetic object.

4. The camouflage and covert communication method based on time-frequency profile curves according to claim 3, characterized in that, A communication frame includes a quantity indicator code and several information codes, each of which is a time-domain vocal pulse signal.

5. The camouflage and covert communication method based on time-frequency profile curves according to claim 1, characterized in that, Step S6 is as follows: S601. Use spectral subtraction and bandpass filter to filter out environmental noise introduced into the communication signal received by the receiving device during transmission; S602. Calculate the short-time energy spectrum of communication signals. The short-time energy of the communication signal at time T is defined as: ； In the formula For communication signals, For sampling points, For frame length, For frame shift; S603 filters out vocal pulses in communication signals based on their short-time energy characteristics; it sets an energy threshold ET, and when the short-time energy of a communication signal is higher than ET, it uses that part of the communication signal as a vocal pulse. S604. Calculate the time interval between each cry pulse in the communication signal sequentially, based on the time interval between adjacent time-domain cry pulse signals within each communication frame. Less than the time interval between different communication frames To distinguish between information codes and quantity indicator codes; S605. Decode each frame sequentially; extract the time-frequency profile curve of each time-domain acoustic pulse signal, and calculate the maximum slope of its time-frequency profile curve. and the number of extreme points Determine the group number to which the corresponding time-domain cry pulse signal belongs; S606. For quantity indicator codes, determine the number of information codes in the corresponding communication frame according to their group number; for information codes, determine the m-bit binary information they represent according to their group number; repeat the above steps until all communication signals are decoded, and finally obtain complete communication information.

6. A camouflage and covert communication device based on time-frequency profile curves, characterized in that, include: The extraction unit is used to collect real vocal samples of biomimetic objects, and extracts time-domain vocal pulse signals based on the short-time energy principle to achieve endpoint detection. The time-frequency profile curve construction unit is used to convert the extracted time-domain cry pulse signal to the time-frequency domain through short-time Fourier transform and obtain the time-frequency profile curve; and to remove outliers in the time-frequency profile curve based on the continuity characteristics of the time-frequency profile curve to obtain a smooth time-frequency profile curve. The calculation unit is used to calculate the maximum slope of the time-frequency profile curve. and the number of extreme points As the first and second levels of hierarchical grouping of time-domain vocal pulse signals; The communication pulse library construction unit is used to combine the requirements of communication rate with the characteristics of the real vocal pulse sequence of the biomimetic object, based on the maximum slope. Divide all time-domain acoustic pulse signals into Groups, based on the number of extreme points Divide all time-domain acoustic pulse signals into Groups are used to divide all time-domain acoustic pulse signals into groups. The group completed the construction of the communication pulse library, among which... , The number of bits used to encode each time-domain acoustic pulse signal should be greater than the number of pulses in the communication pulse library. ; The numbering unit is used to determine the pulse group number to be encoded based on the communication information to be transmitted; The encoding unit is used to encode the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence; The transmitting unit is used to transmit a pre-coded communication pulse sequence to the outside world through a transducer; The filtering unit is used to receive the corresponding communication signals and perform filtering processing. The decoding unit is used to decode the communication signal after it has been processed by the filtering unit to obtain complete communication information.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the camouflage and covert communication method based on time-frequency profile curves as described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the camouflage and covert communication method based on time-frequency profile curves as described in any one of claims 1 to 5.

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