An integrated waveform design for underwater sounding, communication and guidance based on GSFM signal

Abstract

The present invention discloses a waveform design method for underwater detection, communication, and guidance based on GSFM signals, belonging to the fields of radar, signal processing, and underwater vehicle clustering. The method utilizes GSFM signals to adjust parameters (modulation parameters α and ρ) to generate a large number of orthogonal waveforms occupying the same frequency band. Based on this, the Costas sequence is introduced to map the parameters, forming a variant signal that possesses the characteristics of a GSFM signal while also possessing the good autocorrelation and poor cross-correlation characteristics of the Costas sequence. When used in an underwater cluster environment, the waveform of the present invention can simultaneously achieve target detection and communication between cluster nodes, improving the mutual recognition ability between cluster nodes and exhibiting good detection performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar, signal processing and underwater vehicle clusters, and particularly relates to a waveform design method for underwater sounding, communication and guidance integration based on GSFM signals. Background Art

[0002] With the advancement of deep-sea missions, exploring the deep sea and the ocean is the only way to develop marine affairs and build a strong maritime nation. Scientific exploration is inseparable from the development of advanced equipment and technology. Deep-sea exploration uses a variety of underwater vehicles, and their operation inevitably requires the support of underwater communication and detection capabilities.

[0003] Because both underwater acoustic detection and communication systems utilize underwater sound as a carrier, devices often require independent control to avoid mutual interference. This not only creates operational independence when performing different functions, but also reduces system efficiency. Furthermore, with increasing device integration and higher bandwidth requirements for data transmission, spectrum congestion has resulted. Communication and detection, two key functions of underwater vehicles, often require their own frequency bands, further compressing the available frequency bands for each function. Furthermore, due to the complexity and variability of the underwater environment, available spectrum resources for underwater sound are far less abundant than those for terrestrial electromagnetic waves. Furthermore, the presence of numerous noise sources underwater, such as marine life and currents, contributes to a shortage of available spectrum resources. These issues severely hinder the improvement of platform functionality and the advancement of ocean exploration. Furthermore, as underwater equipment is increasingly becoming clustered, ensuring the source of information when communicating between vehicles in a cluster, if the signals used by different users are only vaguely distinguishable, this can make it difficult for users to confirm the source of information during cluster missions, resulting in inaccurate transmissions.

[0004] In summary, in order to improve the efficiency of underwater vehicle systems, it is necessary to integrate detection and communication functions, requiring the same signal to realize two functions. However, when realizing multiple functions in an underwater environment, there is a problem of scarce frequency band resources. Therefore, the present invention proposes an underwater detection, communication and guidance integrated waveform design method based on GSFM signals. Summary of the Invention

[0005] Technical issues to be solved:

[0006] In order to overcome the shortcomings of the prior art, the present invention provides a method for designing an integrated underwater sounding, communication, and guidance waveform based on a GSFM signal. This waveform can simultaneously achieve target detection and mutual communication between cluster nodes when facing an underwater cluster environment. The present invention utilizes the GSFM signal to adjust parameters (modulation parameters α and ρ, instantaneous frequency function FR) to generate a large number of waveforms occupying the same frequency band and orthogonal to each other. Based on this, the Costas sequence is introduced to map the parameters, forming a variant signal that has the characteristics of a GSFM signal while also having the characteristics of a Costas sequence with good autocorrelation and poor cross-correlation. The signal waveform designed by the present invention improves the mutual recognition ability between cluster nodes and has good detection performance.

[0007] The technical solution of the present invention is: a method for designing an integrated underwater sounding, guiding and conducting waveform based on GSFM signals, the specific steps of which are as follows:

[0008] Define signal parameters according to requirements, including signal bandwidth B, center frequency f c , signal length T, sampling frequency f s ;

[0009] Define the sequence parameters of the signal according to the requirements and select the sequence; the sequence parameters include the sequence generation method and sequence length;

[0010] The signal modulation parameter ρ, the initial value of α α0 and the α variation step Δα are defined; where ρ is a dimensionless number used to control the shape of the signal;

[0011] The modulation parameter α is mapped according to the selected sequence, that is, the modulation parameter α of each sub-segment is calculated by the initial value α0 of the modulation parameter α and the change step Δα. i , i = 1, 2, 3... represents the sequence number of the sub-segment;

[0012] Based on the modulation parameters α of each sub-segment i By replacing the fixed modulation parameters in the GSFM frequency control function with variable modulation parameters, the instantaneous frequency function of each sub-segment signal in different time periods can be obtained.

[0013] Based on the instantaneous frequency function of each sub-segment signal, the instantaneous frequency change trend of the variant GSFM signal is obtained, and the instantaneous frequency function of the signal is obtained by combining it with the center frequency. The signal frequency is then adjusted to obtain the instantaneous frequency function of the variant signal, that is, the standardized instantaneous frequency function of the signal.

[0014] Calculating an instantaneous phase function of the signal by integrating the instantaneous frequency function of the variant signal;

[0015] Substituting the instantaneous phase function of the signal into the cosine function and summing them, the time domain mathematical representation of the variant GSFM signal is obtained, that is, the time domain waveform of the signal is obtained.

[0016] A further technical solution of the present invention is: the selected sequence is X = {x1, x2, x3, x4, ...}, and the calculation formula of the modulation parameter of each sub-segment is as follows:

[0017] α i =α0+(X i -1)*Δα

[0018] Among them, α i represents the value of the modulation parameter α corresponding to the i-th sub-segment, α0 represents the initial value of the modulation parameter, and x i represents the i-th sequence value in the sequence, and Δα represents the change step of the modulation parameter α set by the user.

[0019] A further technical solution of the present invention is: the sub-segment length T of the signal i =T / N, where N is the sequence length and T is the total signal length.

[0020] A further technical solution of the present invention is that the calculation formula of the instantaneous frequency function of each sub-segment signal is as follows:

[0021]

[0022] Among them, f inst (t i ) represents the instantaneous frequency function of the signal, t i represents the time variable corresponding to the i-th sub-segment, β represents the modulation scale factor of the signal, β satisfies β=B / 2α, and is used to control the frequency variation range, α i represents the value of the modulation parameter α corresponding to the i-th sub-segment, and the definition of the sinc function is: sinc(t)=sin(t) / t.

[0023] A further technical solution of the present invention is: the calculation formula of the instantaneous frequency function of the variant signal is as follows:

[0024]

[0025] Among them, f inst_norm (t i ) represents the normalized instantaneous frequency function of the signal, f c Indicates the center frequency entered by the user, f inst (t i ) represents the instantaneous frequency of the signal before normalization.

[0026] A further technical solution of the present invention is: the calculation formula of the instantaneous phase function of the signal is as follows:

[0027]

[0028] in, represents the instantaneous phase function within the time range corresponding to the i-th sub-segment, f inst_norm (t i ) represents the normalized instantaneous frequency function of the signal, represents the upper limit of the time variable corresponding to the i-th sub-segment signal, Indicates the lower limit of the time variable corresponding to the i-th sub-segment signal.

[0029] A further technical solution of the present invention is: the time domain mathematical representation of the variant GSFM signal is:

[0030]

[0031] Among them, s(t) is the time domain expression of the generated signal, N is the sequence length, represents the instantaneous phase function within the time range corresponding to the i-th sub-segment, represents the upper limit of the time variable corresponding to the i-th sub-segment signal, Indicates the lower limit of the time variable corresponding to the i-th sub-segment signal.

[0032] A further technical solution of the present invention is: the modulation parameter ρ≥1, when ρ=1, the signal degenerates into an SFM signal.

[0033] A GSFM-based underwater sounding, guiding, and integrated waveform system comprises at least one processor and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to execute the GSFM-based underwater sounding, guiding, and integrated waveform design method.

[0034] A computer-readable digital storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the underwater sounding, guiding and integrated waveform design method based on GSFM signals when executed.

[0035] Beneficial effects

[0036] The beneficial effect of the present invention is that it can provide a signal that can simultaneously realize target detection and communication between cluster nodes in a cluster environment. The specific advantages are as follows:

[0037] 1. The user identification capability of the present invention is significantly improved compared with the traditional GSFM;

[0038] 2. The detection capability of the present invention is superior to that of the linear frequency modulation signal based on Costas sequence encoding and the traditional GSFM signal;

[0039] 3. The application scenarios designed in this invention are detection, positioning, and waveform keying information modulation. The information modulation scheme uses different waveforms to carry different information bits. In the simplest form, one waveform carries 0 and another waveform carries 1, thus enabling communication. To achieve more bits, more waveforms need to be allocated to users. Due to the introduction of Costas sequences in GSFM signals, variable parameters are added to the same frequency band. As a result, the actual control parameters of the signal designed in this article are α, ρ, and Costas sequences. Costas sequences have different orders. By permuting and combining these parameters, more nearly orthogonal signals can be generated for more complex modulation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The correlation comparison diagram between the linear frequency modulation signal set encoded by Costas sequence and the traditional GSFM signal set;

[0041] Figure 2 This is a "spike-shaped" comparison diagram of the ambiguity function of the linear frequency modulation signal encoded by the Costas sequence and the ambiguity function of the GSFM signal;

[0042] Figure 3 This is a simulation diagram of the correlation of signals generated by a cluster serving 16 users in an embodiment of the method of the present invention;

[0043] Figure 4 This is a simulation diagram of a variant signal ambiguity function of a signal generated by a cluster serving 16 users in an embodiment of the method of the present invention;

[0044] Figure 5 0.707 contour map of the ambiguity function of the variant GSFM signal in the embodiment of the method of the present invention;

[0045] Figure 6 0 Doppler cross-section diagram and 0 time delay cross-section diagram of the variant GSFM signal ambiguity function in the embodiment of the method of the present invention. DETAILED DESCRIPTION

[0046] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0047] Although traditional GSFM signals can generate a large number of approximately orthogonal signals by changing parameters, the cross-correlation performance of the signals is not very prominent, such as Figure 1As shown in FIG, a correlation diagram of a linear frequency modulation signal set encoded by a Costas sequence and a traditional GSFM signal set is compared; however, the linear frequency modulation signal encoded by the Costas sequence used for comparison is not as good as the traditional GSFM signal in detection performance, as shown in FIG. Figure 2 As shown in Figure 2, the ambiguity functions of the two signals are compared. It can be seen that the ambiguity function of the GSFM signal is closer to a "nail shape" and has better detection performance.

[0048] Based on the above problems, the present invention provides a variant waveform based on the generalized sinusoidal frequency modulation signal (GSFM), which can provide a signal that can simultaneously realize target detection and communication between cluster nodes when facing a cluster environment, that is, a variant signal waveform based on the GSFM signal for underwater clusters, which has the characteristics of the GSFM signal that can generate a large number of waveforms occupying the same frequency band and orthogonal to each other by adjusting parameters (modulation parameters α and ρ, instantaneous frequency function FR), and at the same time has the characteristics of good autocorrelation and poor cross-correlation of the Costas sequence. The designed waveform can be applied to various application scenarios oriented to clusters and with limited resource space. The specific implementation steps are as follows:

[0049] Step 1: The user defines the required parameters, including the required signal bandwidth B, center frequency f c , signal length T, sampling frequency f s The bandwidth B and the center frequency f c As the control parameter of the spectrum range, the signal length T represents the duration of a single signal, and the sampling frequency f s Used for digital signal sampling.

[0050] Step 2: The user defines the required sequence parameters, including the sequence generation method and sequence length N. The sequence length N also determines the number of sub-segments contained in the variant signal, and also determines the length T of each signal sub-segment. i =T / N, where N is the sequence length and T is the total signal length.

[0051] Step 3: The user defines the signal modulation parameter ρ, the initial value of α α0, and the α variation step Δα. ρ is a dimensionless number used to control the shape of the signal, and ρ ≥ 1. When ρ = 1, the signal degenerates into an SFM signal.

[0052] Step 4: Map the modulation parameter α according to the selected sequence. Let the control sequence be

[0053] X={x1,x2,x3,x4,…}, and the modulation parameters of each sub-segment are calculated using the following formula.

[0054] αi =α0+(x i -1)*Δα

[0055] Among them, α i represents the value of the modulation parameter α corresponding to the i-th sub-segment, α0 represents the initial value of the modulation parameter set by the user, and x i represents the i-th sequence value in the sequence, and Δα represents the change step of the modulation parameter α set by the user.

[0056] Step 5: Calculate the instantaneous frequency function of each sub-segment signal using the following formula.

[0057]

[0058] Among them, f inst (t i ) represents the instantaneous frequency function of the signal, t i represents the time variable corresponding to the i-th sub-segment, β represents the modulation scale factor of the signal, β satisfies β=B / 2α, and is used to control the frequency variation range, α i represents the value of the modulation parameter α corresponding to the i-th sub-segment. The sinc function is defined as follows:

[0059] sinc(t)=sin(t) / t

[0060] Step 6: Using the formula in step 5, we can get the instantaneous frequency change trend of the variant GSFM signal. Based on this trend, we can add the center frequency to get the instantaneous frequency function of the signal. Adjusting the signal frequency using the following formula gives the instantaneous frequency function of the variant signal.

[0061]

[0062] Among them, f inst_norm (t i ) represents the normalized instantaneous frequency function of the signal, f c Indicates the center frequency entered by the user, f inst (t i ) represents the instantaneous frequency of the signal before normalization.

[0063] Step 7: Calculate the instantaneous phase function of the signal by integrating the normalized instantaneous frequency function. The specific calculation formula is as follows:

[0064]

[0065] in, represents the instantaneous phase function within the time range corresponding to the i-th sub-segment, f inst_norm (t i ) represents the normalized instantaneous frequency function of the signal, represents the upper limit of the time variable corresponding to the i-th sub-segment signal, Indicates the lower limit of the time variable corresponding to the i-th sub-segment signal.

[0066] Step 8: Calculate the signal using the following formula:

[0067]

[0068] Among them, s(t) is the time domain expression of the generated signal, N is the sequence length, represents the instantaneous phase function within the time range corresponding to the i-th sub-segment, represents the upper limit of the time variable corresponding to the i-th sub-segment signal, Indicates the lower limit of the time variable corresponding to the i-th sub-segment signal.

[0069] The above technical solution is further described below with reference to the accompanying drawings and examples:

[0070] In this embodiment, the parameters are set as follows: the frequency band is [3000, 6000] Hz, the sub-segment signal length is 0.5, a 5-bit Costas sequence is used, ρ=2, the initial value of α is 150, and the change step size is 20.

[0071] Reference Figure 3 As shown, this embodiment intends to serve a cluster of 16 users. Each user is assigned two waveforms, which requires 32 sequences for control parameters. The correlation of the signal set is simulated to obtain a correlation diagram ( Figure 3 ).from Figure 3 It can be found that the correlation difference of the variant GSFM signal is larger than that of the traditional GSFM signal, showing better user identification ability, indicating that the signal can well distinguish the signal source during communication.

[0072] Reference Figure 4 As shown in FIG. , the simulation results of the variant signal fuzzy function in this embodiment show that the designed signal has good detection performance.

[0073] Based on the ambiguity function of this variant signal, we can get its ambiguity function diagram, 0.707 iso-height section, and zero Doppler-zero delay section diagram as shown below: Figure 4 、 Figure 5 、 Figure 6 shown

[0074] The variant GSFM signal of this embodiment has an extremely ideal fuzzy function. The entire fuzzy function is in the shape of a sharp "thumbnail", and the part outside the main peak is very flat. The 0.707 cross-sectional image is concentrated in the center of the entire image. In the zero Doppler and zero-delay cross-section, the main peak occupies most of the energy, and the part outside the main peak is at an extremely small value. The fuzzy function image shows a strong concentration, demonstrating the excellent detection performance of the variant GSFM signal.

[0075] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A method for designing an integrated underwater sounding, guiding and conducting waveform based on GSFM signal, characterized in that The specific steps are as follows: Define signal parameters according to requirements, including signal bandwidth B, center frequency , signal length T, sampling frequency ; Define the sequence parameters of the signal according to the requirements and select the sequence; the sequence parameters include the sequence generation method and sequence length; Signal modulation parameters 、 Initial value as well as Change step Define; where is a dimensionless number used to control the shape of the signal; Modulation parameters are adjusted according to the selected sequence Mapping is performed by modulating the parameters Initial value of and change step size Calculate the modulation parameters of each sub-segment , i=1, 2, 3... represents the sequence number of the sub-segment; Based on the modulation parameters of each sub-segment By replacing the fixed modulation parameters in the GSFM frequency control function with variable modulation parameters, the instantaneous frequency function of each sub-segment signal in different time periods can be obtained; the calculation formula of the instantaneous frequency function of each sub-segment signal is as follows: in, represents the instantaneous frequency function of the signal, represents the time variable corresponding to the i-th sub-segment, represents the modulation scale factor of the signal, satisfy , used to control the frequency variation range, Indicates the modulation parameter corresponding to the i-th sub-segment The value of the sinc function is defined as: ; Based on the instantaneous frequency function of each sub-segment signal obtained, the instantaneous frequency change trend of the variant GSFM signal is obtained, and the instantaneous frequency function of the signal is obtained by combining it with the center frequency. The signal frequency is then adjusted to obtain the instantaneous frequency function of the variant signal, that is, the standardized instantaneous frequency function of the signal. The calculation formula of the instantaneous frequency function of the variant signal is as follows: in, represents the normalized instantaneous frequency function of the signal, Indicates the center frequency entered by the user; Calculating an instantaneous phase function of the signal by integrating the instantaneous frequency function of the variant signal; Substituting the instantaneous phase function of the signal into the cosine function and summing them, the time domain mathematical representation of the variant GSFM signal is obtained, that is, the time domain waveform of the signal is obtained.

2. The method for designing an integrated underwater sounding, guiding and conducting waveform based on GSFM signals according to claim 1, characterized in that: The selection sequence is , the calculation formula of each sub-segment modulation parameter is as follows: in, Indicates the modulation parameter corresponding to the i-th sub-segment The value of Indicates the initial value of the modulation parameter, represents the i-th sequence value in the sequence, Indicates the modulation parameters set by the user Change step size.

3. The method for designing an integrated underwater sounding, guiding and conducting waveform based on GSFM signals according to claim 2, characterized in that: The sub-segment length of the signal , where N is the sequence length.

4. The method for designing an integrated underwater sounding, guiding and conducting waveform based on GSFM signals according to claim 1, characterized in that: The time domain mathematical representation of the variant GSFM signal is: in, To generate the time domain expression of the signal, N is the sequence length, represents the instantaneous phase function within the time range corresponding to the i-th sub-segment, represents the upper limit of the time variable corresponding to the i-th sub-segment signal, Indicates the lower limit of the time variable corresponding to the i-th sub-segment signal.

5. The method for designing an integrated underwater sounding, guiding and conducting waveform based on GSFM signals according to claim 4, characterized in that: The modulation parameters ,when The signal degenerates into an SFM signal.

6. An underwater sounding, communication and guidance integrated waveform system based on GSFM signals, characterized by: The invention comprises at least one processor and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the underwater sounding, guiding and integrated waveform design method based on GSFM signals as described in any one of claims 1 to 5.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the underwater sounding, guiding and integrated waveform design method based on GSFM signals as described in any one of claims 1 to 5 when executed.

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