A method for bionic covert communication based on multi-phase rotation

Abstract

The present application relates to a kind of based on multiple phase rotation bionic covert communication method, the method comprises: the data to be sent is encoded into binary sequence, and is mapped into corresponding rotating phase sequence;Tooth whale original whistle signal is cut into several segments of sub-signal according to symbol length;Each segment of sub-signal is respectively subjected to hilbert transform and phase rotation to obtain tooth whale modulation whistle signal, and the tooth whale modulation whistle signal is combined with tooth whale original whistle signal and is inserted into the synchronization header to obtain transmitting signal.The present application utilizes hilbert transform to rotate the phase of signal in time domain, modulates information in phase, and a certain amount of information modulation can be completed with only a small number of sampling points, and the communication rate is as high as 2000bps, which improves the data transmission capacity of bionic covert communication;And sound signal is regarded as high-dimensional vector, and the rotation phase is obtained by using vector angle, without the complex signal processing of traditional communication method, information demodulation can be completed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater acoustic communication, in particular to a bionic covert communication method based on multi-ary phase rotation. BACKGROUND

[0002] Covert underwater acoustic communication technology is an important technology for maintaining China's military security and maritime security. However, in order to ensure that the receiving end can accurately decode the signal, the sound signal transmitted by the transmitting end often has a sound source level obviously higher than the ocean background noise. However, due to the openness and unreliability of the underwater acoustic communication channel, the underwater acoustic communication signal with high sound source level is easily intercepted by eavesdroppers. Therefore, how to ensure the concealment and security of communication has become a key problem to be solved in underwater acoustic communication.

[0003] Traditional underwater covert acoustic communication often uses the method of reducing the sound power of the transmitting end signal to make the communication signal submerged in the background noise, so as to achieve the effect of covert communication. However, this method inevitably limits the communication distance and cannot realize long-range underwater acoustic communication. Unlike low signal-to-noise ratio covert underwater acoustic communication, bionic covert communication emphasizes inducing the enemy to exclude the received signal through bionic camouflage to achieve the effect of concealment. This method does not need to reduce the signal-to-noise ratio of the communication signal, and can realize long-distance covert communication underwater. The existing bionic communication technology is based on the actual sampling of beluga whale sound signal samples, and through frequency spectrum shift, frequency compression and expansion, segment replacement and other processing of the time-frequency curve of the signal sample, the information is modulated in the bionic signal, and then the bionic communication is realized. However, the communication rate of the existing method is only 200bps at most, and there is still a lot of room for improvement in practical application. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a bionic covert communication method based on multi-ary phase rotation, which can effectively solve the problem of low communication rate of the existing bionic covert communication.

[0005] The technical scheme of the present application is as follows:

[0006] According to one aspect of the present application, a bionic covert communication method based on multi-ary phase rotation is provided, which comprises:

[0007] encoding the data to be sent into a binary sequence and mapping it into a corresponding rotation phase sequence;

[0008] dividing the beluga whale original whistle signal into a plurality of sub-signals according to the symbol length;

[0009] performing Hilbert transform and phase rotation on each sub-signal to obtain a beluga whale modulated whistle signal, and combining the beluga whale modulated whistle signal with the beluga whale original whistle signal to obtain a transmitting signal after inserting a synchronization header.

[0010] In the above technical solution, the Hilbert transform is used to rotate the phase of the signal in the time domain and modulate the information into the phase. Only a small number of sampling points are needed to complete a certain amount of information modulation, and the communication rate is as high as 2000bps, which greatly improves the data transmission capability of biomimetic covert communication.

[0011] In some embodiments, dividing the original toothed whale whistle signal into several signal segments based on symbol length specifically includes:

[0012] Let the system sampling rate be f. s The communication symbol rate is R s Then the communication bit rate is R. b =log2M*R s Then the symbol length len s =f s / R s ;

[0013] Based on the symbol length len s The whistle signal X(t) is uniformly divided into n sub-signals x(t) = [x1(t), x2(t), ..., x...]. n [(t)], where the length of each sub-signal is equal to the symbol length.

[0014] In the above technical solution, the purpose of this arrangement is to

[0015] The advantage of segmentation is that it is designed to improve the information transmission rate. The finer the segmentation, the more information can be transmitted using fewer points.

[0016] In some embodiments, a toothed whale modulated whistle signal containing several modulated sub-signals is obtained by phase rotation of several sub-signals based on the rotation phase. Specifically, this includes:

[0017] Perform a Hilbert transform on the sub-signal to obtain the corresponding imaginary part signal and analytic signal;

[0018] The phase-rotated signal can be obtained by multiplying the analytical signal by the rotation factor and taking the real part.

[0019] Repeat the above steps until the phase rotation of all sub-mode signals is completed to obtain a toothed whale modulated whistle signal with several modulated sub-signals.

[0020] In the above technical solution, the Hilbert transform is used to rotate the phase of the signal in the time domain and modulate the information into the phase. Only a small number of sampling points are needed to complete a certain amount of information modulation, and the communication rate is as high as 2000bps, which greatly improves the data transmission capability of biomimetic covert communication.

[0021] In some embodiments, the synchronization head is a linear frequency modulated signal.

[0022] In the above technical solutions, linear frequency modulated signals have excellent autocorrelation and cross-correlation characteristics, and large Doppler tolerance, and are often used in signal synchronization heads.

[0023] In some embodiments, the process of performing Hilbert transform and phase rotation on each sub-signal to obtain a toothed whale modulated whistle signal, and then combining this toothed whale modulated whistle signal with the original toothed whale whistle signal and inserting it into a synchronization head to obtain a transmission signal, further includes:

[0024] The received signal is cross-correlated with the local synchronization head to extract the original whistle signal and the modulated whistle signal of the toothed whale, thus completing frame synchronization;

[0025] The extracted original whistle signal and the modulated whistle signal are sliced ​​according to symbol length. The phase difference between each segment is calculated to obtain the rotation phase. The rotation phase is mapped to the corresponding binary sequence, and the binary sequence is decoded to obtain the transmitted information.

[0026] In the above technical solution, a synchronization signal identical to that of the transmitting end is generated locally. This signal is then convolved with the received signal to obtain the cross-correlation peak value. Based on the peak value position and the length of the whistle signal, the original whistle signal and the modulated whistle signal are extracted from the received signal, thus completing frame synchronization. Furthermore, this invention treats the acoustic signal as a high-dimensional vector and uses the vector angle to calculate the rotation phase, achieving information demodulation without the complex signal processing required by traditional communication methods.

[0027] In some embodiments, the step of comparing the phase of the toothed whale modulated whistle signal with the original toothed whale whistle signal, and obtaining the rotation phase using a vector method, specifically includes:

[0028] Based on the symbol length, the toothed whale modulated whistle signal and the original toothed whale whistle signal are divided into n sub-signals; the phase difference of each sub-signal is calculated using the vector dot product formula, which is the rotation phase.

[0029] In the above technical solution, the original whistle signal and the modulated whistle signal are divided into n sub-signals based on the symbol length. Let the original whistle sub-signal be w. i (t), The corresponding vector is y, and the modulated whistle signal is y. i (t), If w is the corresponding vector, then i (t) and y i (t) The phase difference (rotation phase) between the two is... and The vector angle. This invention treats the acoustic signal as a high-dimensional vector and uses the vector angle to obtain the rotation phase, thus completing information demodulation without the complex signal processing of traditional communication methods.

[0030] In some embodiments, the step of mapping the rotation phase to the corresponding binary sequence and decoding the binary sequence to obtain the transmission information is the reverse process of encoding the data to be sent into a binary sequence and mapping it to the corresponding rotation phase sequence.

[0031] In the above technical solution, the demodulation process is accelerated by reversing the operation, and information demodulation can be completed without the complex signal processing of traditional communication methods.

[0032] According to another aspect of the present invention, a biomimetic covert communication device based on multi-level phase rotation is provided, comprising:

[0033] The encoding mapping module, the segmentation module, and the modulation module are connected in sequence.

[0034] The encoding mapping module is used to encode the data to be sent into a binary sequence and map it into a corresponding rotated phase sequence;

[0035] The segmentation module is used to segment the original toothed whale whistle signal into several segments based on the symbol length;

[0036] The modulation module is used to perform Hilbert transform and phase rotation on each sub-signal to obtain the toothed whale modulated whistle signal, and then combine the toothed whale modulated whistle signal with the original toothed whale whistle signal and insert it into the synchronization head to obtain the transmission signal.

[0037] According to another aspect of the present invention, a biomimetic covert communication device based on multi-level phase rotation is provided, comprising:

[0038] At least one processor; and,

[0039] A memory communicatively connected to the at least one processor; wherein,

[0040] The memory stores instructions that can be executed by the at least one processor, which enables the at least one processor to perform a biomimetic covert communication method based on multi-level phase rotation as described above.

[0041] According to another aspect of the present invention, a computer-readable storage medium is provided, which stores a computer program that, when executed by a processor, implements the above-described biomimetic covert communication method based on multi-level phase rotation. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart of an embodiment of the biomimetic covert communication method based on multi-level phase rotation of the present invention.

[0044] Figure 2 This is a schematic diagram of the whistle signal segmentation and modulation process in an embodiment of the biomimetic covert communication method based on multi-level phase rotation of the present invention.

[0045] Figure 3 This is a schematic diagram of the transmission signal generation and frame structure of an embodiment of the biomimetic covert communication method based on multi-level phase rotation of the present invention.

[0046] Figure 4 This is a schematic diagram of an embodiment of the biomimetic covert communication device based on multi-level phase rotation of the present invention. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] refer to Figure 1 A biomimetic covert communication method based on multi-level phase rotation, comprising two parts: a transmitter part and a receiver part;

[0049] I. Transmitter Section

[0050] S1, Encode the data to be transmitted into a binary sequence and map it to the corresponding rotated phase sequence; specifically including the following:

[0051] S11: Encode the data to be transmitted into a binary sequence;

[0052] In this embodiment, the information to be transmitted is encoded into a binary sequence using UTF-8 encoding.

[0053] S12: Map the binary sequence to the corresponding rotation phase;

[0054] In this embodiment, the encoded binary sequence is grouped according to the selected base and mapped to the corresponding rotation phase;

[0055] Furthermore, when using quaternary phase rotation, the binary sequence is divided into groups of 2 bits each, with the corresponding mapping relationships as follows: 00 corresponds to 0·π, 01 corresponds to π / 4, 10 corresponds to π / 2, and 11 corresponds to 3π / 4. For example, the binary sequence [01001011] will be mapped to [π / 4, 0·π, π / 2, 3π / 4].

[0056] S2, the original toothed whale whistle signal is divided into several segments based on symbol length; the signal segmentation and phase mapping diagram is shown below. Figure 2 As shown. Specifically, it includes the following:

[0057] S21. Let the system sampling rate be f. s The communication symbol rate is R s Then the communication bit rate is R. b =log2M*R s Then the symbol length len s =f s / R s In this embodiment, the system sampling rate is 1MHz, the symbol rate is 1000baud, the communication bit rate is 2000bps, and the symbol length is 1000 sampling points.

[0058] S22. Based on the symbol length len obtained in S21 s The whistle signal X(t) is uniformly divided into n sub-signals x(t) = [x1(t), x2(t), ..., x...]. n [(t)], the length of each sub-signal is equal to the symbol length; the advantage of segmentation is that segmentation is to improve the information transmission rate. The finer the segmentation, the more information can be transmitted using fewer points.

[0059] S3. Perform Hilbert transform and phase rotation on each sub-signal to obtain the toothed whale modulated whistle signal. Combine this toothed whale modulated whistle signal with the original toothed whale whistle signal and insert it into the synchronization header to obtain the transmission signal. The diagram of transmission signal generation and frame structure is shown below. Figure 3 As shown. Specifically includes:

[0060] S31. Perform a Hilbert transform on the sub-signal to obtain the corresponding imaginary part and analytic signal; multiply the analytic signal by the rotation factor and take the real part to obtain the phase-rotated signal; repeat the above steps until the phase rotation of all sub-signals is completed to obtain several segments of modulated sub-signals of the toothed whale modulated whistle signal. Specifically, for sub-signal x i Perform a Hilbert transform on (t) to obtain the corresponding imaginary part signal. The formula for the Hilbert transform is as follows;

[0061]

[0062] Wherein, H[x i [t] represents the Hilbert transform, and * represents the convolution operator. Then the analytic signal corresponding to the sub-signal is... Multiplying the analytic signal by the phase rotation factor and taking the real part yields the phase-rotated signal y. i (t), the calculation formula is as follows:

[0063]

[0064] in, To perform the operation of taking the real part, This is the rotation phase.

[0065] After performing the above operations on each sub-signal, the toothed whale modulated whistle signal can be obtained.

[0066] y(t)=[y1(t),y2(t),...,y n (t)].

[0067] S32. Use a linear frequency modulated (LFM) signal as a synchronization head. The LFM signal has excellent autocorrelation and cross-correlation characteristics and a large Doppler tolerance. It is often used in signal synchronization heads. Its expression is as follows.

[0068] LFM(t)=Aexp[j(2πf0t+πkt 2 )]

[0069] Where A is the amplitude of the linear frequency modulated signal, f0 is the initial frequency, and k is the frequency change rate or modulation slope. In this embodiment, the amplitude of the linear frequency modulated signal is 1, the initial frequency is 10kHz, and the modulation slope is 5kHz / s. The original whistle signal and the modulated whistle signal are combined, and after inserting a sync head at the front end, the transmitted signal can be obtained.

[0070] II. Receiver Section

[0071] S4. Perform cross-correlation processing on the received signal and the local synchronization head to extract the original whistle signal and the modulated whistle signal of the toothed whale, and complete frame synchronization. Specifically, this includes: generating a synchronization signal that is consistent with the transmitter locally, performing convolution operation with the received transmitted signal to obtain the cross-correlation peak value, and extracting the original whistle signal and the modulated whistle signal from the received signal based on the peak value and the length of the whistle signal, and completing frame synchronization.

[0072] S5. Slice the extracted original whistle signal and the modulated whistle signal according to symbol length, calculate the phase difference between each segment to obtain the rotated phase, map the rotated phase to the corresponding binary sequence, and decode the binary sequence to obtain the transmitted information. Specifically, this includes:

[0073] S51. Based on the symbol length, the toothed whale modulated whistle signal and the original toothed whale whistle signal are divided into n sub-signals;

[0074] S52. Calculate the phase difference of each sub-signal segment using the vector dot product formula; this is the rotation phase. Specifically:

[0075] Let the original whistle signal be w. i (t), The corresponding vector is y, and the modulated whistle signal is y. i (t), If w is the corresponding vector, then i (t) and y i (t) The phase difference (rotation phase) between the two is... and The vector angle, therefore, rotation phase The calculation formula is as follows:

[0076]

[0077] Here, arccos represents the inverse trigonometric function of the cosine function.

[0078] S53. Map the rotation phase to the corresponding binary sequence, and decode the binary sequence to obtain the transmitted information.

[0079] In this embodiment, the process of rotating phase mapping to a binary sequence is the same as S12, and the process of decoding the binary sequence is the same as S11.

[0080] Table 1. Communication bit error rate under different signal-to-noise ratios

[0081]

[0082] As shown in Table 1, under Gaussian white noise channel conditions, the bit error rate of this method is only 10 at a low signal-to-noise ratio. -4 It has excellent communication performance, which greatly improves the information transmission rate of biomimetic covert communication.

[0083] According to another aspect of this embodiment, a biomimetic covert communication device based on multi-level phase rotation is provided. Please refer to [link to relevant documentation]. Figure 4 This includes: the transmitting end and the receiving end connected to the communication;

[0084] The transmitting end section includes an encoding mapping module, a segmentation module, and a modulation module that are electrically connected in sequence;

[0085] The encoding mapping module is used to encode the data to be sent into a binary sequence and map it into a corresponding rotated phase sequence;

[0086] The segmentation module is used to segment the original toothed whale whistle signal into several segments based on the symbol length;

[0087] The modulation module is used to perform Hilbert transform and phase rotation on each sub-signal to obtain the toothed whale modulated whistle signal, and then combine the toothed whale modulated whistle signal with the original toothed whale whistle signal and insert it into the synchronization head to obtain the transmission signal.

[0088] The receiving end section includes a processing module and a demodulation module that are electrically connected in sequence;

[0089] The processing module is used to receive the transmitted signal, perform cross-correlation processing, extract the modulated whistle signal of the toothed whale and the original whistle signal of the toothed whale, and complete frame synchronization.

[0090] The demodulation module is used to slice the extracted original whistle signal and the modulated whistle signal according to the symbol length, calculate the phase difference between each sub-segment to obtain the rotating phase, map the rotating phase to the corresponding binary sequence, and decode the binary sequence to obtain the transmitted information.

[0091] The principles and methods of this system correspond one-to-one with the aforementioned biomimetic covert communication methods based on multi-level phase rotation, and will not be elaborated here.

[0092] According to another aspect of the present invention, a biomimetic covert communication device based on multi-level phase rotation is provided, comprising:

[0093] At least one processor; and,

[0094] A memory communicatively connected to the at least one processor; wherein,

[0095] The memory stores instructions that can be executed by the at least one processor, which enables the at least one processor to perform a biomimetic covert communication method based on multi-level phase rotation as described above.

[0096] The principle and method of this device correspond one-to-one with the aforementioned biomimetic covert communication method based on multi-level phase rotation, and will not be repeated here.

[0097] According to another aspect of this embodiment, a computer-readable storage medium is provided, storing a computer program that, when executed by a processor, implements the above-described biomimetic covert communication method based on multi-level phase rotation.

[0098] The principle and method of this medium processing correspond one-to-one with the above-mentioned biomimetic covert communication method based on multi-level phase rotation, and will not be repeated here.

[0099] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A biomimetic covert communication method based on multi-level phase rotation, characterized in that, The method includes: The data to be transmitted is encoded into a binary sequence and mapped to the corresponding rotated phase sequence; The original whistle signal of the toothed whale was divided into several segments based on the symbol length; Each sub-signal is subjected to Hilbert transform and phase rotation to obtain the toothed whale modulated whistle signal. This toothed whale modulated whistle signal is then combined with the original toothed whale whistle signal and inserted into the synchronization head to obtain the transmission signal. The received signal is cross-correlated with the local synchronization head to extract the original whistle signal and the modulated whistle signal of the toothed whale, thus completing frame synchronization; The extracted original whistle signal and the modulated whistle signal are sliced ​​according to symbol length, and the phase difference between each segment is calculated to obtain the rotating phase. The rotating phase is then mapped to the corresponding binary sequence, and the binary sequence is decoded to obtain the transmitted information. in, The original whistle signal of the toothed whale was divided into several segments based on the symbol length, specifically including: Assume the system sampling rate is The communication symbol rate is Then the communication bit rate is Then the symbol length ; Based on symbol length , whistle signal The signal is uniformly divided into n segments. The length of each sub-signal is equal to the symbol length; The toothed whale modulated whistle signal is obtained by performing Hilbert transform and phase rotation on each sub-signal, specifically including: Perform a Hilbert transform on the sub-signal to obtain the corresponding imaginary part signal and analytic signal; By multiplying the analytical signal by the rotated phase and taking the real part, the phase-rotated signal can be obtained. Repeat the above steps until all sub-signal phase rotations are completed to obtain a toothed whale modulated whistle signal with several modulated sub-signals.

2. The biomimetic covert communication method based on multi-level phase rotation according to claim 1, characterized in that, The synchronization head is a linear frequency modulated signal.

3. The biomimetic covert communication method based on multi-level phase rotation according to claim 1, characterized in that, The rotation phase is obtained by comparing the phase of the modulated whistle signal from the toothed whale with the phase of the original whistle signal from the toothed whale using a vector method, specifically including: Based on the symbol length, the modulated whistle signal of the toothed whale and the original whistle signal of the toothed whale are divided into n sub-signals; the phase difference of each sub-signal is calculated using the vector dot product formula, which is the rotation phase. Specifically: Let the original whistle signal be , The corresponding vector is used to modulate the whistle signal. , If the corresponding vector is, then and The phase difference between the two, which is a rotational phase, is... and The vector angle, therefore, rotation phase The calculation formula is as follows: in, The inverse trigonometric function representing the cosine function; The rotating phase is mapped to the corresponding binary sequence, and the binary sequence is decoded to obtain the transmitted information.

4. The biomimetic covert communication method based on multi-level phase rotation according to claim 1, characterized in that, The step of mapping the rotating phase to the corresponding binary sequence and decoding the binary sequence to obtain the transmitted information is the reverse process of encoding the data to be sent into a binary sequence and mapping it to the corresponding rotating phase sequence.

5. A biomimetic covert communication device based on multi-level phase rotation, characterized in that, Based on the method according to any one of claims 1-4, it includes: The encoding mapping module, the segmentation module, and the modulation module are connected in sequence. The encoding mapping module is used to encode the data to be sent into a binary sequence and map it into a corresponding rotated phase sequence; The segmentation module is used to segment the original toothed whale whistle signal into several segments based on the symbol length; The modulation module is used to perform Hilbert transform and phase rotation on each sub-signal to obtain the toothed whale modulated whistle signal, and then combine the toothed whale modulated whistle signal with the original toothed whale whistle signal and insert it into the synchronization head to obtain the transmission signal; as well as, The processing module and demodulation module are electrically connected in sequence; The processing module is used to perform cross-correlation processing between the received signal and the local synchronization head, extract the original whistle signal and the modulated whistle signal of the toothed whale, and complete frame synchronization; The demodulation module slices the extracted raw whistle signal and the modulated whistle signal according to symbol length, calculates the phase difference between each segment to obtain the rotating phase, maps the rotating phase to the corresponding binary sequence, and decodes the binary sequence to obtain the transmitted information.

6. A biomimetic covert communication device based on multi-level phase rotation, characterized in that, include: At least one processor; as well as, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, which, when executed by the at least one processor, enables the at least one processor to perform a biomimetic covert communication method based on multi-level phase rotation as described in any one of claims 1 to 4.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements a biomimetic covert communication method based on multi-level phase rotation as described in any one of claims 1 to 4.

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