Underwater sound artificial noise generation method based on double-interference-source alignment

Abstract

The invention belongs to the technical field of underwater acoustic communication, and particularly relates to an underwater acoustic artificial noise generation method based on double-interference-source alignment, in particular to an underwater acoustic artificial noise generation method based on double-interference-source alignment. The objective of the invention is to solve the problem of low security of existing underwater acoustic communication. According to the method, the artificial noise is mutually counteracted at the partner through frequency domain precoding, and the artificial noise is not mutually counteracted at the malicious user by utilizing the difference between the legal channel and the eavesdropping channel, so that the quality of the legal channel is superior to that of the eavesdropping channel, and the physical layer security of the system is enhanced. Through the selective mapping-amplitude limiting peak-to-average ratio suppression method, the peak-to-average ratio of the emitted artificial noise waveform is reduced, and engineering implementation of an artificial noise scheme is facilitated. The artificial noise waveform generation method provided by the invention has good adaptability to the underwater acoustic channel, effectively improves the security of underwater acoustic communication without the position of a malicious user and channel information, and has the advantages of simple operation and low complexity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underwater acoustic communication, and particularly relates to a method for generating underwater acoustic artificial noise through double interference source alignment. BACKGROUND

[0002] Underwater acoustic communication is a core supporting technology for ocean resource exploration, environmental monitoring and national defense security. However, the openness of the underwater acoustic channel also makes underwater information easy to be intercepted and leaked. Artificial noise assisted physical layer security technology is an important category in the field of physical layer security, which realizes information confidentiality at the physical layer by transmitting artificial noise to interfere with malicious nodes in the network while transmitting communication signals. However, transmitting artificial noise will also interfere with the two parties communicating, and it is necessary to establish an artificial noise that can be canceled by cooperative users and cannot be canceled by malicious users. A method for artificial noise assisted physical layer security based on interference alignment is disclosed in Chinese Patent Specification CN118632236A, which uses the obtained channel precoding matrix to perform interference alignment, and can realize interference cancellation at the cooperative party. However, due to the characteristics of low frequency, long propagation delay and multipath effect of underwater acoustic channel, the artificial noise scheme in wireless communication is greatly reduced in effect in underwater acoustic communication. The artificial noise scheme in underwater acoustic communication needs to consider the multipath characteristics of underwater acoustic channel and combine the application requirements of limited underwater resources to design. SUMMARY

[0003] The purpose of the present application is to solve the problem of low security of existing underwater acoustic communication, and a method for generating underwater acoustic artificial noise through double interference source alignment is proposed.

[0004] The specific process of a method for generating underwater acoustic artificial noise through double interference source alignment is as follows:

[0005] Step 1: setting the parameters of the artificial noise signal; setting the parameters of the communication signal;

[0006] A pilot sequence group is generated, which contains P pilot sequences, and each pilot sequence is K long j , K j is the total number of artificial noise subcarriers;

[0007] Step 2: generating an orthogonal frequency division multiplexing waveform based on the pilot sequence group;

[0008] Step 3: cooperative users transmit the orthogonal frequency division multiplexing waveform generated in step 2;

[0009] The interference transmitting source 1 receives the orthogonal frequency division multiplexing waveform transmitted by the cooperative users, processes the received orthogonal frequency division multiplexing waveform transmitted by the cooperative users, and obtains the channel frequency response from the cooperative users to the interference transmitting source 1;

[0010] The interference transmitter 2 receives the orthogonal frequency division multiplexing waveform transmitted by the cooperative user, and processes the received orthogonal frequency division multiplexing waveform transmitted by the cooperative user to obtain the channel frequency response from the cooperative user to the interference transmitter 2;

[0011] The channel frequency response from the interference transmitter 1 to the cooperative user is equal to the channel frequency response from the cooperative user to the interference transmitter 1, and the channel frequency response from the interference transmitter 2 to the cooperative user is equal to the channel frequency response from the cooperative user to the interference transmitter 2, so as to obtain the channel frequency response from the interference transmitter 1 to the cooperative user and the channel frequency response from the interference transmitter 2 to the cooperative user;

[0012] The channel frequency response from the interference transmitter 1 to the cooperative user is M groups;

[0013] The channel frequency response from the interference transmitter 2 to the cooperative user is M groups;

[0014] The channel frequency response from the interference transmitter 1 to the cooperative user includes channel frequency responses on K n frequency points;

[0015] The channel frequency response from the interference transmitter 2 to the cooperative user includes channel frequency responses on K n frequency points;

[0016] The frequency point represents the frequency corresponding to each subcarrier of the artificial noise;

[0017] Step 4: According to the channel frequency response from the M groups of interference transmitters to the cooperative user, the modulation symbol s i,p,q of the qth artificial noise block in the pth artificial noise waveform of the interference transmitter i is calculated, i=1,2;

[0018] Step 5: The modulation symbol s i,p,q , the artificial noise frequency band, and the number of artificial noise subcarriers of the qth artificial noise block are subjected to multicarrier orthogonal frequency division multiplexing modulation to generate P artificial noise waveforms to be screened by the interference transmitter 1 and P artificial noise waveforms to be screened by the interference transmitter 2;

[0019] Step 6: The peak-to-average ratio of the P artificial noise waveforms to be screened by the interference transmitter 1 and the P artificial noise waveforms to be screened by the interference transmitter 2 is calculated;

[0020] The average peak-to-average ratio of the artificial noise waveforms of the two interference transmitters is calculated based on the peak-to-average ratio of the artificial noise waveforms, p is recorded as p0 when the average peak-to-average ratio takes the minimum value, and the 2 artificial noise waveforms corresponding to p0 are output and

[0021] Step 7: The energy average of the artificial noise waveform is calculated, and the maximum average value is selected as estp ;

[0022] with the mean e stp as the step length to form an increasing set of clipping thresholds;

[0023] perform clipping operation on the set of signals and to obtain the clipping threshold Γ;

[0024] Step 8: based on the artificial noise waveform obtained in step 6 and the clipping threshold Γ obtained in step 7, obtain the final artificial noise waveform and

[0025] The beneficial effects of the present application are:

[0026] The purpose of the present application is to provide a method for generating underwater acoustic artificial noise with double interference source alignment, generating constellation symbols of the interference source through double interference source frequency domain precoding, and reducing the peak-to-average ratio of the artificial noise through a selective mapping-clipping peak-to-average ratio suppression method, and finally generating a pair of artificial noise waveforms that can cancel each other at the cooperative user. The method of the present application utilizes the difference in space channel to achieve interference cancellation of cooperative users and interference reservation of malicious users, and can achieve high security of underwater acoustic communication.

[0027] The present application first configures fixed parameters known to both parties of communication, then the cooperative user transmits a channel measurement waveform, and the jammer obtains the channel frequency response from the interference source to the cooperative user through reciprocity; the jammer calculates the modulation symbols according to the channel frequency response and adds an artificial phase; then the artificial noise waveform is generated, and the waveform distortion peak-to-average ratio suppression is considered by selecting the waveform with the smallest peak-to-average ratio, and finally a pair of artificial noise waveforms that can cancel each other at the cooperative user are generated.

[0028] The present application makes the artificial noise cancel each other at the cooperative party through frequency domain precoding, and utilizes the difference between the legal channel and the eavesdropping channel to make the artificial noise not cancel each other at the malicious user, so that the quality of the legal channel is better than that of the eavesdropping channel, and the physical layer security of the system is enhanced. The selective mapping-clipping peak-to-average ratio suppression method reduces the peak-to-average ratio of the transmitted artificial noise waveform, which is beneficial to the engineering implementation of the artificial noise scheme. The artificial noise waveform generation method proposed in the present application has good adaptability to underwater acoustic channels, effectively improves the security of underwater acoustic communication without the position and channel information of the malicious user, and has the advantages of simple operation and low complexity. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Flow chart of the method for generating underwater acoustic artificial noise with double interference source alignment;

[0030] Figure 2 is the simulation scene graph;

[0031] Figure 3a is the channel diagram from interference source 1 to cooperative user;

[0032] Figure 3b is the channel diagram from interference source 2 to cooperative user;

[0033] Figure 4 is the peak-to-average ratio diagram of the artificial noise waveform;

[0034] Figure 5a Time domain diagram of artificial noise waveform received by cooperative users;

[0035] Figure 5b Time-frequency domain diagram of artificial noise waveform received by cooperative users;

[0036] Figure 6 The distribution diagram of the artificial noise power of the eavesdropper in the simulation area;

[0037] Figure 7 This is the scene diagram of the water tank test;

[0038] Figure 8 This is the waveform diagram of the signal received by the cooperative user in the experiment;

[0039] Figure 9 This is the signal waveform diagram received by the malicious user in the experiment;

[0040] Figure 10 The comparison chart of pilot signal-to-noise ratio between cooperative users and eavesdropping users. DETAILED DESCRIPTION

[0041] Specific embodiment 1: This embodiment is a method for generating underwater acoustic artificial noise with dual interference sources aligned. The specific process is as follows:

[0042] Symbol description: Bold indicates vector or matrix, represents the passband signal, * represents the convolution operation, denotes dot product calculation, E(·) denotes mathematical expectation, j denotes imaginary unit, and π and e denote constants.

[0043] Step 1: Set the parameters of the artificial noise signal; set the parameters of the communication signal;

[0044] Generate a pilot sequence group, which contains P pilot sequences, and each pilot sequence is K long. j , K j is the total number of artificial noise subcarriers;

[0045] Step 2: Generate an Orthogonal Frequency Division Multiplexing (OFDM) waveform for measuring channel frequency response based on the pilot sequence group;

[0046] Step 3: The cooperative user (the receiving end) transmits the orthogonal frequency division multiplexing waveform generated in Step 2;

[0047] The interference transmitter 1 receives the orthogonal frequency division multiplexing waveform transmitted by the cooperative user, processes the received orthogonal frequency division multiplexing waveform transmitted by the cooperative user, and obtains the channel frequency response from the cooperative user to the interference transmitter 1;

[0048] The interference transmitter 2 receives the orthogonal frequency division multiplexing waveform transmitted by the cooperative user, processes the received orthogonal frequency division multiplexing waveform transmitted by the cooperative user, and obtains the channel frequency response from the cooperative user to the interference transmitter 2;

[0049] Assuming that the transmitting end, the receiving end, and the interference source are stationary and the sea condition is less than or equal to level three, the channel frequency response from the interference transmitter 1 to the cooperative user is equal to the channel frequency response from the cooperative user to the interference transmitter 1, and the channel frequency response from the interference transmitter 2 to the cooperative user is equal to the channel frequency response from the cooperative user to the interference transmitter 2, thereby obtaining the channel frequency response from the interference transmitter 1 to the cooperative user and the channel frequency response from the interference transmitter 2 to the cooperative user;

[0050] The channel frequency response from the interference transmitter 1 to the cooperative user is M groups;

[0051] The channel frequency response from the interference transmitter 2 to the cooperative user is M groups;

[0052] The channel frequency response from the interference transmitter 1 to the cooperative user includes channel frequency responses on K n frequency points;

[0053] The channel frequency response from the interference transmitter 2 to the cooperative user includes channel frequency responses on K n frequency points;

[0054] The frequency point represents the frequency corresponding to each subcarrier of the artificial noise;

[0055] Step 4: According to the channel frequency responses from the M interference transmitters to the cooperative user, the modulation symbol s i,p,q of the qth artificial noise block in the pth artificial noise waveform of the interference transmitter i is calculated, i = 1, 2;

[0056] Step 5: The modulation symbol s i,p,q , the artificial noise frequency band, and the number of artificial noise subcarriers of the qth artificial noise block are subjected to multi-carrier orthogonal frequency division multiplexing modulation to generate P artificial noise waveforms to be screened by the interference transmitter 1 and P artificial noise waveforms to be screened by the interference transmitter 2;

[0057] Step 6: Calculate the peak-to-average ratio of P artificial noise waveforms to be screened for interference source 1 and P artificial noise waveforms to be screened for interference source 2;

[0058] Calculate the average peak-to-average ratio of the artificial noise waveforms of the two interference sources based on the peak-to-average ratio of the artificial noise waveforms, and screen p that makes the average peak-to-average ratio take the minimum value as p0, and output the two artificial noise waveforms corresponding to p0 and

[0059] Step 7: Calculate the average energy of the artificial noise waveforms, and screen the maximum average value as e stp ;

[0060] Form an increasing set of clipping thresholds with the average value e stp as a step size;

[0061] Clip and with the set of clipping thresholds to obtain the clipping threshold Γ;

[0062] Step 8: Based on the artificial noise waveforms obtained in step 6 and the clipping threshold Γ obtained in step 7, obtain the final artificial noise waveform and

[0063] Specific implementation method two: The difference between this implementation method and the specific implementation method one is that the parameters of the artificial noise signal are set in step 1; and the parameters of the communication signal are set.

[0064] Generate a pilot sequence group, which contains P pilot sequences, and each pilot sequence has a length of K j , K j is the total number of artificial noise subcarriers;

[0065] The specific process is as follows:

[0066] Set the parameters of the artificial noise signal, which include the artificial noise frequency band and the number of artificial noise subcarriers, and the total number of artificial noise subcarriers is K j ;

[0067] Set the parameters of the communication signal, which include the communication frequency band and the number of communication subcarriers;

[0068] The artificial noise frequency band is greater than the communication frequency band; for example, the communication signal frequency band is 9-15 kHz, and the artificial noise signal frequency band is 8-16 kHz;

[0069] The total number of artificial noise subcarriers K j is greater than the number of communication subcarriers;

[0070] The pilot sequence group is (quadrature phase keying modulation), p = 1, 2, ..., P;

[0071] in, Indicates the first pilot sequence in the pilot sequence group, Indicates the second pilot sequence in the pilot sequence group, represents the pth pilot sequence in the pilot sequence group, represents the Pth pilot sequence in the pilot sequence group;

[0072] The pth pilot sequence in the pilot sequence group Generated by quadrature phase keying modulation, expressed as:

[0073]

[0074] Among them, r is a random number, r = ±1; j is the imaginary unit, j 2 =-1; k′=1,2,…,K j ;

[0075] The artificial noise frequency band, number of subcarriers, and pilot sequence group are known to both communicating parties (the communicating parties are the transmitter and the receiver);

[0076] Other steps and parameters are the same as those in the first embodiment.

[0077] Specific embodiment three: This embodiment differs from specific embodiment one or two in that in step 2, an orthogonal frequency division multiplexing (OFDM) waveform for measuring channel frequency response is generated based on the pilot sequence group;

[0078] The specific process is:

[0079] An orthogonal frequency division multiplexing (OFDM) waveform is set to include M orthogonal frequency division multiplexing OFDM blocks;

[0080] The mth Orthogonal Frequency Division Multiplexing (OFDM) block The generation process of is shown as follows:

[0081]

[0082] based on Obtaining M orthogonal frequency division multiplexing blocks, wherein the M orthogonal frequency division multiplexing blocks constitute an orthogonal frequency division multiplexing waveform;

[0083] in,

[0084] w n (t) represents the window function,

[0085] k′ represents the k′th;

[0086] represents the number of artificial noise subcarriers of the k′th pilot sequence in the mth pilot sequence group; m=1,2,…,M; satisfying M<P;

[0087] f c represents the center frequency of artificial noise;

[0088] The center frequency indicates the center of the frequency band. The center frequency = starting frequency + B J / 2,B J Indicates the bandwidth of artificial noise. For example, if the frequency band of artificial noise is 8-16, B J That is 16-8=8kHz, the starting frequency is 8kHz, and the center frequency is 8+4, which is 12kHz;

[0089] t represents time;

[0090] T d Indicates the symbol length, T d =K j / B J , K j Indicates the total number of artificial noise subcarriers, B J represents the bandwidth of artificial noise;

[0091] T cp is the length of the cyclic prefix (set); Re represents the real part.

[0092] Other steps and parameters are the same as those in the first or second embodiment.

[0093] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that in step 3, the cooperative user (receiving end) transmits the orthogonal frequency division multiplexing waveform generated in step 2;

[0094] Interference source 1 receives the OFDM waveform transmitted by the cooperative user, processes the received OFDM waveform transmitted by the cooperative user, and obtains the channel frequency response from the cooperative user to interference source 1;

[0095] Interference source 2 receives the OFDM waveform transmitted by the cooperative user, and processes the received OFDM waveform transmitted by the cooperative user to obtain the channel frequency response from the cooperative user to interference source 2;

[0096] Assuming that "the transmitting end, receiving end and interference source are static and the sea condition is less than or equal to level three", the channel frequency response of the interference transmitting source 1 to the cooperative user is equal to the channel frequency response of the cooperative user to the interference transmitting source 1, the channel frequency response of the interference transmitting source 2 to the cooperative user is equal to the channel frequency response of the cooperative user to the interference transmitting source 2, so as to obtain the channel frequency response of the interference transmitting source 1 to the cooperative user and the channel frequency response of the interference transmitting source 2 to the cooperative user;

[0097] The channel frequency response of the interference transmitting source 1 to the cooperative user is M groups;

[0098] The channel frequency response of the interference transmitting source 2 to the cooperative user is M groups;

[0099] The channel frequency response of the interference transmitting source 1 to the cooperative user includes the channel frequency response on K n frequency points;

[0100] The channel frequency response of the interference transmitting source 2 to the cooperative user includes the channel frequency response on K n frequency points;

[0101] The frequency point represents the frequency corresponding to each subcarrier of the artificial noise;

[0102] The specific process is as follows:

[0103] Step 31: The cooperative user transmits the orthogonal frequency division multiplexing waveform generated in step 2;

[0104] The interference transmitting source 1 receives the orthogonal frequency division multiplexing waveform transmitted by the cooperative user;

[0105] The mth orthogonal frequency division multiplexing block transmitted by the cooperative user and received by the interference transmitting source i is represented as:

[0106]

[0107] Wherein, h i (t) represents the channel frequency response of the cooperative user to the interference transmitting source i, represents the background noise of the mth orthogonal frequency division multiplexing block, and the background noise in the environment is Gaussian white noise; represents convolution;

[0108] represents the mth orthogonal frequency division multiplexing block;

[0109] The Fourier transform is performed on to obtain the sampling value Y(k) of the kth frequency point; represented as:

[0110]

[0111] Wherein, ​

[0112] Indicates the kth frequency point of the mth OFDM block in the pilot sequence group, k = 1, 2, ..., K n ;K n is the total number of frequency points;

[0113] Y i,m (k) represents the sampling value of the mth OFDM block transmitted by the cooperative user received by the interference source i at the kth frequency point;

[0114] H i (k) represents the channel frequency response from the cooperative user to the interference transmitter i;

[0115] n m (k) represents the k-th frequency background noise of the m-th OFDM block;

[0116] is continuous, Y i,m (k) is discrete;

[0117] The frequency value corresponding to the kth frequency point in the passband is the starting frequency + k×B J / K n ;

[0118] The frequency value corresponding to the kth frequency point in the baseband is -B J / 2+k×B J / K n ;

[0119] Step 32: Based on the sample value Y of the mth OFDM block transmitted by the cooperative user received by the interference transmitter i at the kth frequency point i,m (k), and obtain the estimated value of the channel frequency response from the cooperative user to the interference source i; expressed as:

[0120]

[0121] in, represents the estimated value of the channel frequency response from the cooperative user to the interference transmitter i;

[0122] H i (k) is the actual value, and the actual value remains unchanged;

[0123] Step 33: Assuming that "at the transmitting end, the receiving end, and the interference source are stationary and the sea state is less than or equal to level 3", the channel frequency response from interference source 1 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 1, and the channel frequency response from interference source 2 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 2, thereby obtaining the channel frequency response from interference source 1 to the cooperative user and the channel frequency response from interference source 2 to the cooperative user;

[0124] The channel frequency response of the interference transmitter 1 to the cooperative user is M groups;

[0125] The channel frequency response of the interference transmitter 2 to the cooperative user is M groups;

[0126] The channel frequency response of the interference transmitter 1 to the cooperative user includes the channel frequency response on K n frequency points;

[0127] The channel frequency response of the interference transmitter 2 to the cooperative user includes the channel frequency response on K n frequency points.

[0128] The other steps and parameters are the same as one of the first to third embodiments.

[0129] The fifth embodiment is different from one of the first to fourth embodiments in that in the step 4, the modulation symbol s i,p,q of the qth artificial noise block in the pth artificial noise waveform of the interference transmitter i is calculated according to the channel frequency response of the M groups of interference transmitters to the cooperative user, i = 1, 2; the specific process is as follows:

[0130]

[0131] wherein,

[0132] p represents the serial number of the pilot sequence, is the pth pilot sequence in the pilot sequence group;

[0133] represents the random phase of the qth block, obeys the Gaussian distribution;

[0134] s i,p,q represents the modulation symbol of the qth artificial noise block in the pth artificial noise waveform of the interference transmitter i, i = 1, 2;

[0135] w i,m represents the weight vector of the channel frequency response of the mth group of interference transmitters i to the cooperative party to be solved, m = 1, 2, …, M;

[0136] u i,1 represents the weight vector of the channel frequency response of the 1st group of interference transmitters i to the cooperative party to be solved;

[0137] represents the vector dot product; E m represents the expectation;

[0138] E m (w i,m) represents the mean value of the weight vector of the channel frequency response from the M groups of interference emission source i to the cooperation party to be solved.

[0139] The other steps and parameters are the same as those in the first to fourth embodiments.

[0140] Specific embodiment 6: This embodiment differs from any one of specific embodiments 1 to 5 in that the specific solution method of the weight vector to be solved is as follows:

[0141] At the kth frequency point, the weight w 1,m (k), w 2,m (k),u 1,m (k),u 2,m (k) satisfies the following formula:

[0142]

[0143] in,

[0144] represents the estimated value of the channel frequency response from the interference source 1 at the kth frequency point to the cooperative user, represents the estimated value of the channel frequency response from the k-th frequency cooperative user to the interference source 1;

[0145] represents the estimated value of the channel frequency response from the interference source 2 at the kth frequency point to the cooperative user, represents the estimated value of the channel frequency response from the k-th frequency cooperative user to the interference source 2;

[0146] w 1,m (k) is the weight of the channel frequency response from the mth group of interference source 1 to the partner at the kth frequency point;

[0147] w 2,m (k) is the weight of the channel frequency response from the mth group of interference source 2 to the partner at the kth frequency point;

[0148] u 1,m (k) is the weight of the channel frequency response from the mth group of interference source 1 to the partner at the kth frequency point;

[0149] u 2,m (k) is the weight of the channel frequency response from the mth group of interference source 2 to the partner at the kth frequency point;

[0150] Put the equation The known quantity in Decomposed into scalar and complex values, the weight solution process is shown as follows

[0151]

[0152] Available

[0153]

[0154] wherein,

[0155] a, c are scalars;

[0156] e -jb , e -jd are complex values; j is an imaginary unit, j 2 = -1;

[0157] b, d are the amplitudes of the complex numbers;

[0158] Thus, the weight w 1,m (k), w 2,m (k), u 1,m (k), u 2,m (k) is solved.

[0159] The k = 1, 2...K n frequency points are traversed to obtain the weight vector w 1,m , w 2,m , u 1,m , u 2,m .

[0160] Similarly, when m = 1, the weight w 1,1 (k), w 2,1 (k), u 1,1 (k), u 2,1 (k) is solved by the following formula.

[0161]

[0162] The k = 1, 2...K n frequency points are traversed to obtain the weight vector w 1,1 , w 2,1 , u 1,1 , u 2,1 .

[0163] The other steps and parameters are the same as one of the first to fourth embodiments.

[0164] Embodiment seven: The difference between this embodiment and one of the first to sixth embodiments is that in step 5, the modulation symbol s i,p,q , the artificial noise frequency band, the number of artificial noise subcarriers, the multi-carrier orthogonal frequency division multiplexing modulation is performed to generate the P artificial noise waveforms of the interference emission source 1 to be screened and the P artificial noise waveforms of the interference emission source 2 to be screened.

[0165] The specific process is as follows:

[0166] Step 51: The generation process of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 1 is shown in the following formula:

[0167]

[0168] Step 52: The generation process of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 2 is shown in the following formula:

[0169]

[0170] in,

[0171] represents the qth artificial noise block in the pth artificial noise waveform of the interference emission source 1;

[0172] represents the qth artificial noise block in the pth artificial noise waveform of the interference emission source 2;

[0173] s 1,p,q represents the modulation symbol of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 1;

[0174] s 2,p,q represents the modulation symbol of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 2;

[0175] f c represents the center frequency of artificial noise;

[0176] k′ represents the k′th item; t represents time;

[0177] T d Indicates the symbol length, T d =K n / B J ;

[0178] B J represents the bandwidth of artificial noise;

[0179] w 1n (t) represents the window function,

[0180] w 2n (t) represents the window function,

[0181] T cp is the length of the cyclic prefix; Re represents the real part;

[0182] Step 53:

[0183] Synthesizing Q artificial noise blocks in the pth artificial noise waveform of the interference transmitting source 1 in ascending order to form an artificial noise waveform P waveforms of the interference transmitting source 1 form P artificial noise waveforms

[0184] Synthesizing Q artificial noise blocks in the pth artificial noise waveform of the interference transmitting source 2 in ascending order to form an artificial noise waveform P waveforms of the interference transmitting source 2 form P artificial noise waveforms

[0185] The other steps and parameters are the same as one of the first to sixth embodiments.

[0186] The eighth embodiment is different from one of the first to seventh embodiments in that the peak-to-average ratio of the P artificial noise waveforms of the interference transmitting source 1 to be screened and the P artificial noise waveforms of the interference transmitting source 2 to be screened is calculated in step 6.

[0187] The average peak-to-average ratio of the artificial noise waveforms of the two interference transmitting sources is calculated based on the peak-to-average ratio of the artificial noise waveforms, p is recorded as p0 when the average peak-to-average ratio takes the minimum value, and the two artificial noise waveforms corresponding to p0 are output and

[0188] The specific process is as follows:

[0189] Step 61: calculating the peak-to-average ratio PAR of the pth artificial noise waveform of the interference transmitting source 1 to be screened 1,p ; the calculation is as follows:

[0190]

[0191] wherein,

[0192] represents the energy average of several seconds in a waveform, which varies with t and has many

[0193] represents the maximum value of several seconds in a waveform, which varies with t and has many

[0194] PAR 1,p represents the peak-to-average ratio of the pth artificial noise waveform of the interference transmitting source 1 to be screened;

[0195] represents the pth artificial noise waveform of the interference transmitting source 1 to be screened;

[0196] Step 62: Calculate the peak-to-average ratio (PAR) of the pth artificial noise waveform to be screened for the interference transmitter 2 2,p ; the calculation is as follows:

[0197]

[0198] wherein,

[0199] represents the energy average of (the waveform has several seconds, and changes with t has many);

[0200] represents the maximum value of (the waveform has several seconds, and changes with t has many);

[0201] PAR 2,p represents the peak-to-average ratio of the pth artificial noise waveform to be screened for the interference transmitter 2;

[0202] represents the pth artificial noise waveform to be screened for the interference transmitter 2;

[0203] Step 63: Based on the peak-to-average ratio (PAR) of the pth artificial noise waveform to be screened for the interference transmitter 1 1,p and the peak-to-average ratio (PAR) of the pth artificial noise waveform to be screened for the interference transmitter 2 2,p , calculate the average peak-to-average ratio (MPAR) of the artificial noise waveforms of the two interference transmitters Screening makes MPAR p minimum, and p is recorded as p0;

[0204] Output the 2 artificial noise waveforms corresponding to p0 and

[0205] The other steps and parameters are the same as one of the first to seventh embodiments.

[0206] The ninth embodiment is different from one of the first to eighth embodiments in that the energy average of the artificial noise waveform is calculated in step 7, and the maximum average value is recorded as e stp ;

[0207] The average value e stp is used as a step to form an increasing set of clipping thresholds;

[0208] The clipping threshold set is used to clip and to obtain the clipping threshold Γ;

[0209] The specific process is:

[0210] Step 71:

[0211] Calculate the energy average of the artificial noise waveform and select the largest average value as

[0212] in,

[0213] Express request The average energy value of

[0214] Express request The average energy value of

[0215] Express request and Maximum value;

[0216] Step 72:

[0217] Take the mean value e stp The step size forms an increasing set of limiting thresholds [8e stp ,9e stp ,10e stp ,11e stp ,12e stp ,13e stp ,14e stp ,15e stp ,16e stp ](the minimum example value is 8 and the maximum is 16);

[0218] Step 73: Set the limit threshold to and Perform a limiting operation to obtain the limiting threshold Γ; the process is:

[0219] Step 731: Initialization

[0220] in, is an integer;

[0221] Step 732: Find greater than All artificial noise waveforms, calculate Medium to large The length of all artificial noise waveforms is Percentage of overall length;

[0222] exist Find greater than All artificial noise waveforms, calculate Medium to large The length of all artificial noise waveforms is Percentage of overall length;

[0223] If both percentages are less than one ten-thousandth, the limit threshold

[0224] If both percentages are less than 1 / 10,000, then execute step 733;

[0225] Step 733: Make Re-execute step 732 until both percentages are less than 1 / 10,000, and obtain the clipping threshold.

[0226] The other steps and parameters are the same as those in Specific Embodiments 1 to 8.

[0227] Specific embodiment 10: This embodiment differs from any one of specific embodiments 1 to 9 in that the artificial noise waveform obtained in step 8 is based on step 6. And the limiting threshold Γ obtained in step 7, the final artificial noise waveform is obtained and

[0228] Expressed as

[0229]

[0230] where sgn(·) is the sign function.

[0231] The above steps 1-3 involve the jammer and the cooperating user, and steps 4-8 are completed locally on the jammer.

[0232] The other steps and parameters are the same as those in Specific Embodiments 1 to 9.

[0233] The following examples are used to verify the beneficial effects of the present invention:

[0234] Example 1:

[0235] The following is a demonstration with the accompanying figures. The parameters of the dual interference source alignment artificial noise are set to 8-16kHz, the center frequency is 12kHz, the symbol length is 0.256s, the number of subcarriers is 2048, and the cyclic prefix length is set to 50ms. A frame contains 8 symbols, and the peak-to-average ratio suppression parameter is 10 -4 , the selective mapping contains 9 pilot groups to be selected. Set up an open water area of ​​5km×5km with a maximum depth of no more than 50m. The sound source is placed at the center of the coordinate system, where the interference sound source depths are 12m and 14m, and the communication sound source depth is 13m. The cooperative user Bob is located at [-1500m, 0m, 25m], with a horizontal distance of 1.5km. Malicious users may exist at any location in the scenario. See the attached simulation scenario Figure 2 The simulated channel data set is generated by Bellop sound field simulation software. The channel from the interference source to the cooperative user is shown in the attached Figure 3a 、 3b As shown in Figure 2, the channel delay spread reaches the order of 40ms.

[0236] The peak-to-average ratio obtained by screening 9 pilot groups using the selective mapping algorithm is shown in the attached figure. Figure 4 The peak-to-average ratio of the artificial noise waveform generated by the 7th pilot is the lowest. After the limiting operation, the average peak-to-average ratio of the artificial noise waveform is reduced from 11.86dB to 11.37dB. The cancellation of artificial noise at the receiving end is shown in the attached figure. Figure 5a 、 5b From the attached Figure 5a 、 5b As can be seen from the figure, the artificial noises of the two interference sources are aligned to cancel each other out in the cooperative party, and only a very small amount of interference remains except for the cyclic prefix position. When the artificial noise signal with a peak power of 1 is transmitted, the residual artificial noise power of the cooperative user is 5.412×10 -7 (When channel measurement is relatively accurate). Assuming that the eavesdropper may be located anywhere in the three-dimensional area, Bellhop simulation was used to obtain the channel from the interference source to each point in the area (5km×5km, depth 50m). The obtained channel data set has a total of 251 (axial distance) × 51 (depth) × 36 (angle) data, totaling 460,836 data points. The average power distribution at the receiving end is shown in the attached figure. Figure 6 ,Using the channel diversity, 96.63% of the regions achieved an artificial noise power greater than 0.05. ,Averaging the 460,836 data points, the average artificial noise power at the ,malicious user is 0.0872, which is much larger than the residual artificial noise power of ,cooperative users.

[0237] To verify the performance of artificial noise in a real underwater acoustic environment, an underwater acoustic test was conducted in a 1m×0.5m×0.5m water tank with a water depth of about 0.2m. The equipment layout is shown in the attached Figure 7 The interference source and the communication source simultaneously transmit the communication signal and the artificial noise signal (the peak value of the artificial noise signal is 0.2, and the peak value of the communication signal is 0.18). The ratio of the transmitted communication signal power to the interference signal power is 0.895. The signal waveform received by the cooperative user is shown in the attached figure. Figure 8 The signal waveform received by the malicious user is shown in the attached Figure 9 The artificial noise power of the cooperative user is 0.151, the artificial noise power of the malicious user is 1.382, and the ratio of the artificial noise of the eavesdropping party to the cooperative party is 9.15 (9.61dB). The bit error rate at the cooperative user is 0, and the bit error rate at the malicious user is 0.50. When there is no artificial noise, the bit error rate of both the cooperative user and the eavesdropping user is 0. See the attached figure for a comparison of the pilot signal-to-noise ratio. Figure 10The pilot signal-to-noise ratio (SNR) of cooperative users fluctuated around 10dB, while that of malicious users fluctuated around -3dB. The pilot SNR dropped by approximately 13dB after transmitting artificial noise. The experimental results show that artificial noise has a much greater impact on malicious users than on cooperative users. The system enables secure underwater acoustic communications that cooperative users can correctly decode but malicious users cannot.

[0238] The present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for generating underwater artificial noise with dual interference sources aligned, characterized by: The specific process of the method is: Step 1: Set the parameters of the artificial noise signal; set the parameters of the communication signal; Generate a pilot sequence group, which contains P pilot sequences, and each pilot sequence is K long. j , K j is the total number of artificial noise subcarriers; Step 2: Generate an orthogonal frequency division multiplexing waveform based on the pilot sequence group; Step 3: The cooperating user transmits the OFDM waveform generated in step 2; Interference source 1 receives the OFDM waveform transmitted by the cooperative user, processes the received OFDM waveform transmitted by the cooperative user, and obtains the channel frequency response from the cooperative user to interference source 1; Interference source 2 receives the OFDM waveform transmitted by the cooperative user, and processes the received OFDM waveform transmitted by the cooperative user to obtain the channel frequency response from the cooperative user to interference source 2; The channel frequency response from interference source 1 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 1, and the channel frequency response from interference source 2 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 2, thereby obtaining the channel frequency response from interference source 1 to the cooperative user and the channel frequency response from interference source 2 to the cooperative user; The channel frequency response from the interference source 1 to the cooperative user is M groups; The channel frequency response from the interference source 2 to the cooperative user is M groups; The channel frequency response from the interference source 1 to the cooperative user includes K n Channel frequency response at each frequency point; The channel frequency response from the interference source 2 to the cooperative user includes K n Channel frequency response at each frequency point; The frequency point indicates the frequency corresponding to each subcarrier of the artificial noise; Step 4: Based on the channel frequency response from the M groups of interference sources to the cooperative user, calculate the modulation symbol s of the qth artificial noise block in the pth artificial noise waveform of the interference source i i,p,q , i=1,2; Step 5: Modulate the symbol s of the qth artificial noise block i,p,q , artificial noise frequency band, and number of artificial noise subcarriers to perform multi-carrier orthogonal frequency division multiplexing modulation to generate P artificial noise waveforms to be screened for interference emission source 1 and P artificial noise waveforms to be screened for interference emission source 2; Step 6: Calculate the peak-to-average ratio of the P artificial noise waveforms to be screened from interference source 1 and the P artificial noise waveforms to be screened from interference source 2; Calculate the average peak-to-average ratio of the artificial noise waveforms of the two interference emission sources based on the peak-to-average ratio of the artificial noise waveforms. The value of p when the average peak-to-average ratio takes the minimum value is recorded as p0, and the two artificial noise waveforms corresponding to p0 are output. and Step 7: Calculate the energy average of the artificial noise waveform and select the largest average value as e stp ; Take the mean value e stp forming an increasing set of clipping thresholds for the step size; Limit threshold set and Perform a limiting operation to obtain a limiting threshold Γ; Step 8: Artificial noise waveform based on step 6 And the limiting threshold Γ obtained in step 7, the final artificial noise waveform is obtained and 2. The method for generating underwater artificial noise with dual interference sources aligned according to claim 1, characterized in that: In the step 1, the parameters of the artificial noise signal are set; the parameters of the communication signal are set; Generate a pilot sequence group, which contains P pilot sequences, and each pilot sequence is K long. j , K j is the total number of artificial noise subcarriers; The specific process is: Set the parameters of the artificial noise signal. The parameters of the artificial noise signal include: artificial noise frequency band and number of artificial noise subcarriers. The total number of artificial noise subcarriers is K. j indivual; Set the parameters of the communication signal, including the communication frequency band and the number of communication subcarriers; The artificial noise frequency band is larger than the communication frequency band; The total number of artificial noise subcarriers K j Greater than the number of communication subcarriers; The pilot sequence group is in, Indicates the first pilot sequence in the pilot sequence group, Indicates the second pilot sequence in the pilot sequence group, represents the pth pilot sequence in the pilot sequence group, represents the Pth pilot sequence in the pilot sequence group; The pth pilot sequence in the pilot sequence group Generated by quadrature phase keying modulation, expressed as: Among them, r is a random number, r = ±1; j is the imaginary unit, j 2 =-1; k′=1,2,…,K j ; The artificial noise frequency band, the number of subcarriers, and the pilot sequence group are known to both communicating parties.

3. The method for generating underwater artificial noise with dual interference sources aligned according to claim 2, characterized in that: In step 2, an orthogonal frequency division multiplexing waveform is generated based on the pilot sequence group; the specific process is: Setting an orthogonal frequency division multiplexing waveform to include M orthogonal frequency division multiplexing OFDM blocks; The mth OFDM block The generation process of is shown as follows: based on Obtaining M orthogonal frequency division multiplexing blocks, wherein the M orthogonal frequency division multiplexing blocks constitute an orthogonal frequency division multiplexing waveform; in, w n (t) represents the window function, k′ represents the k′th; Indicates the number of artificial noise subcarriers of the k′th artificial noise subcarrier of the mth pilot sequence in the pilot sequence group; m = 1, 2, …, M; Satisfy M<P; f c represents the center frequency of artificial noise; t represents time; T d Indicates the symbol length, T d =K j / B J , K j Indicates the total number of artificial noise subcarriers, B J represents the bandwidth of artificial noise; T cp is the length of the cyclic prefix; Re represents the real part.

4. The method for generating underwater artificial noise with dual interference sources aligned according to claim 3, characterized in that: In step 3, the cooperative user transmits the orthogonal frequency division multiplexing waveform generated in step 2; Interference source 1 receives the OFDM waveform transmitted by the cooperative user, processes the received OFDM waveform transmitted by the cooperative user, and obtains the channel frequency response from the cooperative user to interference source 1; Interference source 2 receives the OFDM waveform transmitted by the cooperative user, and processes the received OFDM waveform transmitted by the cooperative user to obtain the channel frequency response from the cooperative user to interference source 2; The channel frequency response from interference source 1 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 1, and the channel frequency response from interference source 2 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 2, thereby obtaining the channel frequency response from interference source 1 to the cooperative user and the channel frequency response from interference source 2 to the cooperative user; The channel frequency response from the interference source 1 to the cooperative user is M groups; The channel frequency response from the interference source 2 to the cooperative user is M groups; The channel frequency response from the interference source 1 to the cooperative user includes K n Channel frequency response at each frequency point; The channel frequency response from the interference source 2 to the cooperative user includes K n Channel frequency response at each frequency point; The frequency point indicates the frequency corresponding to each subcarrier of the artificial noise; The specific process is: Step 31: The cooperative user transmits the OFDM waveform generated in step 2; Interference transmitter 1 receives the orthogonal frequency division multiplexing waveform transmitted by the cooperative user; The mth OFDM block transmitted by the cooperative user received by the interference source i Expressed as: Among them, h i (t) represents the channel frequency response from the cooperative user to the interference source i, represents the background noise of the mth OFDM block, * represents convolution; represents the mth OFDM block; right Perform Fourier transform to obtain the sampling value Y(k) of the kth frequency point; it is expressed as: in, Indicates the kth frequency point of the mth OFDM block in the pilot sequence group, k = 1, 2, ..., K n ;K n is the total number of frequency points; Y i,m (k) represents the sampling value of the mth OFDM block transmitted by the cooperative user received by the interference source i at the kth frequency point; H i (k) represents the channel frequency response from the cooperative user to the interference transmitter i; n m (k) represents the k-th frequency background noise of the m-th OFDM block; Step 32: Based on the sample value Y of the mth OFDM block transmitted by the cooperative user received by the interference transmitter i at the kth frequency point i,m (k), and obtain the estimated value of the channel frequency response from the cooperative user to the interference source i; expressed as: in, represents the estimated value of the channel frequency response from the cooperative user to the interference transmitter i; Step 33: The channel frequency response from interference source 1 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 1, and the channel frequency response from interference source 2 to the cooperative user is equal to the channel frequency response from the cooperative user to interference source 2, thereby obtaining the channel frequency response from interference source 1 to the cooperative user and the channel frequency response from interference source 2 to the cooperative user; The channel frequency response from the interference source 1 to the cooperative user is M groups; The channel frequency response from the interference source 2 to the cooperative user is M groups; The channel frequency response from the interference source 1 to the cooperative user includes K n Channel frequency response at each frequency point; The channel frequency response from the interference source 2 to the cooperative user includes K n The channel frequency response at each frequency point.

5. The method for generating underwater artificial noise with dual interference sources aligned according to claim 4, characterized in that: In step 4, the modulation symbol s of the qth artificial noise block in the pth artificial noise waveform of the interference source i is calculated based on the channel frequency response from the M groups of interference sources to the cooperative user. i,p,q , i=1,2; the specific process is: in, p represents the number of the pilot sequence, is the pth pilot sequence in the pilot sequence group; represents the random phase of the qth block, Obey Gaussian distribution; s i,p,q represents the modulation symbol of the qth artificial noise block in the pth artificial noise waveform of the interference transmitter i, i = 1, 2; w i,m The weight vector representing the channel frequency response from the mth group of interference source i to the partner to be solved, m = 1, 2, ..., M; u i,1 The weight vector representing the channel frequency response from the first group of interference transmitter i to the partner to be solved; Represents vector dot product; E m Expressing hope; E m (w i,m ) represents the mean value of the weight vector of the channel frequency response from the M groups of interference emission source i to the cooperation party to be solved.

6. The method for generating underwater artificial noise with dual interference sources aligned according to claim 5, characterized in that: The specific solution method of the weight vector to be solved is as follows: At the kth frequency point, the weight w 1,m (k), w 2,m (k),u 1,m (k),u 2,m (k) satisfies the following formula: in, represents the estimated value of the channel frequency response from the interference source 1 at the kth frequency point to the cooperative user, represents the estimated value of the channel frequency response from the k-th frequency cooperative user to the interference source 1; represents the estimated value of the channel frequency response from the interference source 2 at the kth frequency point to the cooperative user, represents the estimated value of the channel frequency response from the k-th frequency cooperative user to the interference source 2; w 1,m (k) is the weight of the channel frequency response from the mth group of interference source 1 to the partner at the kth frequency point; w 2,m (k) is the weight of the channel frequency response from the mth group of interference source 2 to the partner at the kth frequency point; u 1,m (k) is the weight of the channel frequency response from the mth group of interference source 1 to the partner at the kth frequency point; u 2,m (k) is the weight of the channel frequency response from the mth group of interference source 2 to the partner at the kth frequency point; Put the equation The known quantity in Decomposed into scalar and complex values, the weight solution process is shown as follows Available in, a and c are scalars; e -jb 、e -jd is a complex value; j is an imaginary unit, j 2 =-1; b and d are the arguments of the complex numbers; So far, the weight w is solved 1,m (k), w 2,m (k),u 1,m (k),u 2,m (k); Traverse k=1,2...K n frequency points, and obtain the weight vector w 1,m , w 2,m ,u 1,m ,u 2,m ; Similarly, when m=1, the weight w is obtained by solving the following formula: 1,1 (k), w 2,1 (k),u 1,1 (k),u 2,1 (k); Traverse k=1,2...K n frequency points, and obtain the weight vector w 1,1 , w 2,1 ,u 1,1 ,u 2,1 .

7. The method for generating underwater artificial noise with dual interference sources aligned according to claim 6, characterized in that: The modulation symbol s of the qth artificial noise block in step 5 is i,p,q , artificial noise frequency band, number of artificial noise subcarriers, and multi-carrier orthogonal frequency division multiplexing modulation to generate P artificial noise waveforms to be screened for interference emission source 1 and P artificial noise waveforms to be screened for interference emission source 2; The specific process is: Step 51: The generation process of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 1 is shown in the following formula: Step 52: The generation process of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 2 is shown in the following formula: in, represents the qth artificial noise block in the pth artificial noise waveform of the interference emission source 1; represents the qth artificial noise block in the pth artificial noise waveform of the interference emission source 2; s 1,p,q represents the modulation symbol of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 1; s 2,p,q represents the modulation symbol of the qth artificial noise block in the pth artificial noise waveform of the interference emission source 2; f c represents the center frequency of artificial noise; k′ represents the k′th item; t represents time; T d Indicates the symbol length, T d =K n / B J ; B J represents the bandwidth of artificial noise; w 1n (t) represents the window function, w 2n (t) represents the window function, T cp is the length of the cyclic prefix; Re represents the real part; Step 53: The Q artificial noise blocks in the pth artificial noise waveform of the interference emission source 1 are synthesized into an artificial noise waveform in ascending order. The P waveforms of interference source 1 constitute P artificial noise waveforms The Q artificial noise blocks in the pth artificial noise waveform of the interference emission source 2 are synthesized into an artificial noise waveform in ascending order. The P waveforms of interference source 2 constitute P artificial noise waveforms 8. The method for generating underwater artificial noise with dual interference sources aligned according to claim 7, characterized in that: In step 6, the peak-to-average ratio of the P artificial noise waveforms to be screened from interference emission source 1 and the P artificial noise waveforms to be screened from interference emission source 2 is calculated; Calculate the average peak-to-average ratio of the artificial noise waveforms of the two interference emission sources based on the peak-to-average ratio of the artificial noise waveforms. The value of p when the average peak-to-average ratio takes the minimum value is recorded as p0, and the two artificial noise waveforms corresponding to p0 are output. and The specific process is: Step 61: Calculate the peak-to-average ratio (PAR) of the pth artificial noise waveform to be screened from the interference source 1 1,p ; The calculation is as follows: in, Express request The average energy value of Express request Maximum value; PAR 1,p Indicates the peak-to-average ratio of the pth artificial noise waveform to be screened out of the interference emission source 1; Indicates the pth artificial noise waveform to be screened out from interference source 1; Step 62: Calculate the peak-to-average ratio (PAR) of the pth artificial noise waveform to be screened out from the interference source 2 2,p ; The calculation is as follows: in, Express request The average energy value of Express request Maximum value; PAR 2,p represents the peak-to-average ratio of the pth artificial noise waveform to be screened out by the interference emission source 2; represents the pth artificial noise waveform to be screened out by the interference emission source 2; Step 63: Calculate the peak-to-average ratio (PAR) of the pth artificial noise waveform to be screened based on the interference source 1. 1,p The peak-to-average ratio PAR of the pth artificial noise waveform to be screened out by the interference source 2 2,p , calculate the average peak-to-average ratio of the artificial noise waveforms of the two interfering emission sources Screening for MPAR p The smallest p is denoted as p0; Output 2 artificial noise waveforms corresponding to p0 and 9. The method for generating underwater artificial noise with dual interference sources aligned according to claim 8, characterized in that: In step 7, the energy average value of the artificial noise waveform is calculated, and the largest average value is selected and recorded as e stp ; Take the mean value e stp forming an increasing set of clipping thresholds for the step size; Limit threshold set and Perform a limiting operation to obtain a limiting threshold Γ; The specific process is: Step 71: Calculate the energy average of the artificial noise waveform and select the largest average value as in, Express request The average energy value of Express request The average energy value of Express request and Maximum value; Step 72: Take the mean value e stp The step size forms an increasing set of limiting thresholds [8e stp ,9e stp ,10e stp ,11e stp ,12e stp ,13e stp ,14e stp ,15e stp ,16e stp ]; Step 73: Set the limit threshold to and Perform a limiting operation to obtain the limiting threshold Γ; the process is: Step 731: Initialization in, is an integer; Step 732: Find greater than All artificial noise waveforms, calculate Medium to large The length of all artificial noise waveforms is Percentage of overall length; exist Find greater than All artificial noise waveforms, calculate Medium to large The length of all artificial noise waveforms is Percentage of overall length; If both percentages are less than one ten-thousandth, the limit threshold If both percentages are less than 1 / 10,000, then execute step 733; Step 733: Make Re-execute step 8732 until both percentages are less than 1 / 10,000, and obtain the clipping threshold.

10. The method for generating underwater artificial noise with dual interference sources aligned according to claim 9, characterized in that: The artificial noise waveform obtained in step 8 is based on step 6 And the limiting threshold Γ obtained in step 7, the final artificial noise waveform is obtained and Expressed as where sgn(·) is the sign function.

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