CN-117834079-B - Camouflage hidden communication method and device based on time-frequency contour curve

CN117834079BCN 117834079 BCN117834079 BCN 117834079BCN-117834079-B

Abstract

The invention discloses a camouflage hidden communication method and device based on a time-frequency contour curve, which comprises the steps of collecting real sound samples of a bionic object, realizing endpoint detection based on a short-time energy principle, further extracting time-domain sound pulse signals, obtaining the time-frequency contour curve, performing smoothing operation, respectively calculating the maximum slope k max and the number n of extreme points of the time-frequency contour curve corresponding to each time-domain sound pulse signal, performing hierarchical grouping on all time-domain sound pulse signals, determining pulse group numbers to be encoded according to communication information to be transmitted, encoding the communication information to be transmitted according to the determined pulse group numbers to obtain a communication pulse sequence, transmitting the encoded communication pulse sequence outwards through a transducer, performing filtering processing after receiving the corresponding communication signals by a receiving device, and then decoding the communication signals to finally obtain complete communication information. The method uses animal sound in nature as communication carrier, and improves communication safety and communication rate.

Inventors

JIANG JIAJIA
GUO TONGTONG
YANG XUBAO
LI ZHUOCHEN
YAO QINGWANG
LI ZHAOMING
WEI BIN

Assignees

天津大学

Dates

Publication Date: 20260512
Application Date: 20231031

Claims (8)

1. A camouflage hidden communication method based on a time-frequency contour curve is characterized by comprising the following steps: S1, converting a time domain sound pulse signal of a bionic object into a time-frequency domain through short-time Fourier transform, and obtaining a time-frequency contour curve, wherein the mathematical expression of the short-time Fourier transform of the time domain sound pulse signal is as follows: ; In the formula (1) In order to be able to take time, In order to be a frequency of the light, In units of imaginary numbers, In order for the time delay to be a time delay, In order to perform a window function of the short-time fourier transform, The time domain sound pulse signal to be converted is obtained; s2, eliminating wild points in the time-frequency profile curve according to the continuity characteristics of the time-frequency profile curve to obtain a smooth time-frequency profile curve; S3, respectively calculating the maximum slope of the time-frequency profile curve corresponding to each time-domain sound pulse signal And number of extreme points And the time domain sound pulse signals are layered and grouped, and the requirements of communication speed and the characteristics of the real sound pulse sequence of the bionic object are combined according to the maximum slope Dividing all time-domain sounding pulse signals into Group according to extreme point number Dividing all time-domain sounding pulse signals into Groups, thereby dividing all time-domain sounding pulse signals into Group, complete the construction of communication pulse library, wherein , The number of pulses in the communication pulse bank should be greater than the number of bits encoded for each time-domain sounding pulse signal ; S4, determining a corresponding pulse group number according to the communication information to be transmitted; s5, coding the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence; S6, transmitting the coded communication pulse sequence outwards through the transducer, filtering after receiving the corresponding communication signal by the receiving device, and then decoding the communication signal to finally obtain the complete communication information.
2. The camouflage hidden communication method based on the time-frequency profile curve according to claim 1, wherein the step S4 is specifically as follows: s401, firstly, partitioning communication information to be transmitted according to m bits of each block; S402, calculating the group number G of the time domain sound pulse signal corresponding to the communication information to be transmitted of each block, wherein G is the communication information to be transmitted of each group Decimal numbers corresponding to the bit binary numbers.
3. The camouflage hidden communication method based on the time-frequency profile curve according to claim 1, wherein the step S5 is specifically as follows: S501, inserting a quantity indicating code CNI as a frame head of a communication frame for a certain communication frame, and ensuring that the number of information codes in each communication frame accords with the statistical rule of a real sound pulse sequence of a bionic object in order to ensure the concealment; s502, every time interval Taking m bits from communication information to be transmitted, determining a group number to be inserted with a time domain sounding pulse signal, randomly selecting a time domain sounding pulse signal from a corresponding group as the communication signal, and completing encoding of one frame of communication signal until the number of the time domain sounding pulse signals in a corresponding communication frame reaches a specified value of a number indication code; the time interval between the sound-calling pulse signals in different time domains accords with the statistical rule of the real sound-calling pulse sequence of the bionic object; s503, passing time interval Then inserting a quantity indication code as a frame head of a new frame communication signal, and continuing to encode the communication information to be transmitted according to the encoding rule of the step S502, and circulating until all the communication information to be transmitted is encoded, so as to obtain a communication pulse sequence; the time interval between different communication frames accords with the statistical rule of the real sound-calling pulse sequence of the bionic object.
4. The method of claim 3, wherein a communication frame includes a number of indicator codes and a plurality of information codes, each of the number of indicator codes and the information codes being time-domain sounding pulse signals.
5. The camouflage hidden communication method based on the time-frequency profile according to claim 1, wherein the step S6 is specifically as follows: S601, filtering environmental noise introduced in a transmission process of a communication signal received by a receiving device by utilizing spectral subtraction and a band-pass filter; S602, calculating short-time energy spectrum of communication signal The short-time energy of the communication signal at the time T is defined as: ; In the middle of In order for the communication signal to be a signal, In order to sample the point of the sample, For the frame length to be a function of the frame length, Frame shift; s603, screening out the sound pulse in the communication signal through the short-time energy characteristic of the communication signal, setting an energy threshold ET, and taking the part of the communication signal as the sound pulse when the short-time energy of the communication signal is higher than the ET; S604, sequentially calculating the time intervals among the sound pulses in the communication signals according to the intervals among adjacent time domain sound pulse signals in each communication frame Less than the time interval between different communication frames To distinguish the information codes and the quantity indication codes; s605, sequentially decoding each frame, extracting the time-frequency contour curve of each time-domain sound pulse signal, and calculating to obtain the maximum slope of the time-frequency contour curve And number of extreme points Determining the group number of the corresponding time domain sound pulse signal; S606, determining the number of the information codes in the corresponding communication frame according to the group number of the information codes, determining the represented m bit binary information according to the group number of the information codes, and repeating the steps until all communication signals are decoded, so as to finally obtain the complete communication information.
6. A camouflage covert communication device based on a time-frequency profile, comprising: The extraction unit is used for collecting real sound samples of the bionic object, realizing endpoint detection based on a short-time energy principle and further extracting a time domain sound pulse signal; The time-frequency contour curve construction unit is used for converting the extracted time-domain sound pulse signal into a time-frequency domain through short-time Fourier transformation to obtain a time-frequency contour curve, and eliminating wild points in the time-frequency contour curve according to the continuity characteristics of the time-frequency contour curve to obtain a smooth time-frequency contour curve; a calculating unit for calculating the maximum slope of the time-frequency profile curve And number of extreme points A first layer and a second layer which are layered and grouped by the time domain sound pulse signal; The communication pulse library construction unit is used for combining the requirements of communication speed and the characteristics of the real sound-calling pulse sequence of the bionic object according to the maximum slope Dividing all time-domain sounding pulse signals into Group according to extreme point number Dividing all time-domain sounding pulse signals into Groups, thereby dividing all time-domain sounding pulse signals into Group, complete the construction of communication pulse library, wherein , The number of pulses in the communication pulse bank should be greater than the number of bits encoded for each time-domain sounding pulse signal ; The numbering unit is used for determining a pulse group number to be encoded according to the communication information to be transmitted; the coding unit is used for coding the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence; A transmitting unit for transmitting the coded communication pulse sequence outwards through the transducer; the filtering unit is used for receiving the corresponding communication signals and performing filtering processing; And the decoding unit is used for decoding the communication signal processed by the filtering unit to obtain complete communication information.
7. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the camouflage covert communication method based on a time-frequency profile of any one of claims 1 to 5 when the program is executed by the processor.
8. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the camouflage covert communication method based on a time-frequency profile according to any one of claims 1 to 5.

Description

Camouflage hidden communication method and device based on time-frequency contour curve Technical Field The invention relates to the field of sound wave wireless communication, in particular to a method for realizing high-speed bionic camouflage communication by utilizing the maximum slope and pole number of an animal sound pulse time-frequency contour curve to encode communication information in a scene with high requirements on communication concealment. Background The sound wave camouflage hidden communication technology is an information hidden transmission technology based on a sound channel, namely, the sound wave is adopted as a carrier wave to carry out data transmission, and the sound wave camouflage hidden communication technology has good concealment. The acoustic wave belongs to a mechanical wave, has different characteristics from the radio wave belonging to an electromagnetic wave, and has the characteristics of simple equipment and difficult shielding compared with a radio communication mode. Under the condition that the mature electromagnetic wave shielding interference technology exists at present, acoustic wave communication becomes an important communication means in the fields of military, information and the like. A large number of animals which are small in size, wide in geographic distribution and loved to be singly or pairwise active and have flood and changeable crying exist in the nature, a means for camouflage communication in the air at present is to search templates in common animal crying to generate a camouflage object library, so that a modulation signal carrying communication information is matched with a communication environment as far as possible, and even if the communication signal is intercepted, the communication signal can be regarded as common animal crying by an interceptor to be filtered, thereby realizing camouflage communication. The enemy can only realize effective interference by continuously transmitting high-power broadband interference sound waves, but the location of the interference device is easily exposed, and the hearing of all people and animals in the interference environment can be damaged temporarily or permanently, so that the interference cost is excessive. Based on time-frequency analysis of the bionic object syllable-calling pulse, proper time-frequency characteristics are selected to describe and quantify the bionic object syllable-calling pulse, and the method is an important basis for realizing bionic camouflage hidden communication. Disclosure of Invention The invention aims to overcome the defects in the prior art and provides a bionic camouflage hidden communication coding and decoding method and device by utilizing the maximum slope of an animal sound pulse time-frequency profile curve and the number of extreme points as characteristics. The invention aims at realizing the following technical scheme: a camouflage hidden communication method based on a time-frequency contour curve comprises the following steps: S1, converting a time domain sound pulse signal of a bionic object into a time-frequency domain through short-time Fourier transform, and obtaining a time-frequency contour curve, wherein the mathematical expression of the short-time Fourier transform of the time domain sound pulse signal is as follows: In the formula (1), t is time, f is frequency, j is an imaginary unit, tau is time delay, h (tau-t) is a window function for performing short-time Fourier transform, usually a Hamming window, and x (t) is a time domain sound pulse signal to be transformed; s2, eliminating wild points in the time-frequency profile curve according to the continuity characteristics of the time-frequency profile curve to obtain a smooth time-frequency profile curve; S3, respectively calculating the maximum slope k max and the extreme point number n of a time-frequency profile curve corresponding to each time-domain sound pulse signal, and carrying out hierarchical grouping on all the time-domain sound pulse signals, dividing all the time-domain sound pulse signals into m 1 groups according to the maximum slope k max and dividing all the time-domain sound pulse signals into m 2 groups according to the extreme point number n, dividing all the time-domain sound pulse signals into 2 m groups according to the extreme point number n, and completing construction of a communication pulse library, wherein 2 m＝m1*m2 and m are bit numbers coded by each time-domain sound pulse signal, and the pulse number in the communication pulse library is greater than 2 m; s4, determining a corresponding pulse group number according to the communication information to be transmitted; s5, coding the communication information to be transmitted according to the determined pulse group number to obtain a communication pulse sequence; S6, transmitting the coded communication pulse sequence outwards through the transducer, filtering after receiving the corresponding communication sign