Underwater detection-conduction integrated waveform design based on GSFM signal

Abstract

The invention discloses an underwater detection and conduction integrated waveform design method based on a GSFM signal, and belongs to the technical field of radar and signal processing and underwater vehicle clusters. According to the method, a large number of waveforms which occupy the same frequency band and are orthogonal to each other are generated by adjusting parameters (modulation parameters alpha and rho) through a GSFM signal, a Costas sequence is introduced on this basis to map the parameters, and a variant signal which has the characteristics of the GSFM signal and also has the characteristics of good autocorrelation and poor cross correlation of the Costas sequence is formed. The waveform can simultaneously realize target detection and mutual communication between nodes of the cluster when facing an underwater cluster environment, so that the mutual identification capability between the nodes of the cluster is improved, and the detection performance is relatively good.

Description

Technical Field

[0001] The invention belongs to the technical field of radar, signal processing and underwater vehicle cluster, and in particular relates to a waveform design method for underwater sounding, communicating and guiding integration based on GSFM signals. Background Art

[0002] With the proposal of deep-sea mission goals, going to the deep sea and the ocean is the only way to develop marine undertakings and build a strong marine nation. Scientific investigation is inseparable from the development of advanced equipment and technology. In deep-sea development, various underwater vehicles will be used, and in the process of working, underwater communication and detection functions will inevitably be needed.

[0003] Since both underwater acoustic detection and communication systems use underwater sound as a carrier, the devices often need to be controlled separately to avoid mutual interference. When completing different functions, not only are the operations independent, but the efficiency of the system is also reduced. At the same time, in terms of underwater spectrum resources, with the increasing integration of equipment and the higher bandwidth requirements for data transmission, the spectrum is overcrowded. Communication and detection are two important functions of underwater vehicles, and their frequency bands are often designed independently, which again compresses the frequency bands that can be used by different functions. And due to the complexity and variability of the underwater environment, the available spectrum resources for underwater sound are far less abundant than those in the electromagnetic wave environment on land. In addition, there are a large number of noise sources in the underwater environment, such as marine life, water flow, etc., which have caused a shortage of available spectrum resources underwater. All of the above problems seriously restrict the improvement of platform functions and the development of ocean exploration. In addition, as the development of underwater equipment is gradually tending to cluster development, in order to ensure that the source of information can be clearly identified when the vehicles in the cluster communicate with each other, if the signals used by different users are slightly different, it will be difficult for users to confirm the source of information when the cluster performs tasks, resulting in the failure of the transmitted information.

[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, there is a problem of shortage of frequency band resources when realizing multiple functions in underwater environments. 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 avoid the shortcomings of the prior art, the present invention provides a method for designing an underwater sounding, communicating and guiding integrated waveform based on a GSFM signal. When facing an underwater cluster environment, the waveform can simultaneously realize target detection and mutual communication between cluster nodes. The present invention uses GSFM signals to adjust parameters (modulation parameters α and ρ, instantaneous frequency function FR) to generate a large number of waveforms that occupy the same frequency band and are orthogonal to each other, and introduces a Costas sequence on this basis to map the parameters, thereby forming a variant signal that has the characteristics of a GSFM signal and the characteristics of a Costas sequence with good autocorrelation and poor mutual 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, and the specific steps 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 the sequence length;

[0010] The signal modulation parameter ρ, the initial value α0 of α and the step size Δα of α are defined; wherein 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. Then, the signal frequency is adjusted to obtain the instantaneous frequency function of the variant signal, that is, the standardized instantaneous frequency function of the signal.

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

[0015] Substitute the instantaneous phase function of the signal into the cosine function and sum them to obtain the time domain mathematical representation of the variant GSFM signal, that is, the time domain waveform of the signal.

[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 size 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: 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 proportional 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 instantaneous frequency function of the normalized 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 so that the at least one processor can 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 guiding integrated waveform design method based on GSFM signals when executed.

[0035] Beneficial Effects

[0036] The beneficial effect of the present invention is that: when facing a cluster environment, the present invention can provide a signal that can simultaneously realize target detection and mutual communication between cluster nodes. 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 coding and the traditional GSFM signal;

[0039] 3. The application scenarios designed in the present invention are detection, positioning and information modulation of "waveform keying". The information modulation scheme is to carry different information bits through different waveforms. Taking the simplest form as an example, one waveform carries 0 and the other waveform carries 1, so that communication can be achieved. To achieve more bits, more waveforms need to be allocated to users. Since the Costas sequence is introduced in the GSFM signal, the corresponding same frequency band is added with variable parameters, so that the actual control parameters of the signal designed in this paper are α, ρ and Costas sequence, and the Costas sequence has different orders. Through the arrangement and combination of these parameters, more approximately orthogonal signals can be generated for more complex modulation methods. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 2 The "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 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 A simulation diagram of a variant signal fuzzy function of a signal generated by a cluster serving 16 users in an embodiment of the method of the present invention;

[0044] Figure 5 It is the 0.707 contour map of the fuzzy 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 method embodiment of the present invention. DETAILED DESCRIPTION

[0046] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used 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. 1 , 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, by comparing the fuzzy functions of the two signals, it can be seen that the fuzzy 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 a 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 a GSFM signal for underwater clusters, which has the characteristics of a 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 has the characteristics of good autocorrelation and poor mutual correlation of Costas sequences. The designed waveform can be applied to various application scenarios facing clusters and resource space constraints. 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 the 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 step size of α change 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 by 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 size of the modulation parameter α set by the user.

[0056] Step 5: Calculate the instantaneous frequency function of each sub-segment signal by 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 proportional 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 as follows:

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

[0060] Step 6: Through the formula in step 5, the instantaneous frequency change trend of the variant GSFM signal can be obtained. Based on the above trend, the center frequency can be added to obtain the instantaneous frequency function of the signal. The signal frequency can be adjusted through the following formula to obtain the instantaneous frequency function of the variant signal.

[0061]

[0062] Among them, f inst_norm (t i ) represents the instantaneous frequency function of the normalized 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 by:

[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 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, the simulation result of the variant signal fuzzy function in this embodiment shows that the designed signal has good detection performance.

[0073] Based on the variant signal, the ambiguity function is calculated to obtain its ambiguity function diagram, 0.707 iso-height section, and zero Doppler-zero delay section diagram as shown in the figure 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 presents a sharp "thumbnail" shape, and the part outside the main peak is very flat. The 0.707 section image is concentrated in the center of the entire image. In the zero Doppler and zero delay 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 is to be understood that the above embodiments are exemplary 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 intent 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 f c , signal length T, sampling frequency f s ; Define the sequence parameters of the signal according to the requirements and select the sequence; the sequence parameters include the sequence generation method and the sequence length; The signal modulation parameter ρ, the initial value α0 of α and the step size Δα of α are defined; wherein ρ is a dimensionless number used to control the shape of the signal; 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; 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. 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. Then, the signal frequency is adjusted to obtain the instantaneous frequency function of the variant signal, that is, the standardized instantaneous frequency function of the signal. Calculating the instantaneous phase function of the signal by integrating the instantaneous frequency function of the variant signal; Substitute the instantaneous phase function of the signal into the cosine function and sum them to obtain the time domain mathematical representation of the variant GSFM signal, that is, the time domain waveform of the signal.

2. According to the method for designing an integrated waveform of underwater sounding, communication and guidance based on GSFM signal in claim 1, it is characterized by: The selected sequence is X={x1, x2, x3, x4, ...}, and the calculation formula of the modulation parameters of each sub-segment is as follows: a i =α0+(x i -1)*Da 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 size of the modulation parameter α set by the user.

3. According to claim 2, a method for designing an integrated waveform of underwater sounding, communication and guidance based on GSFM signal, characterized in that: The sub-segment length of the signal is T i =T / N, where N is the sequence length and T is the total signal length.

4. According to claim 3, a method for designing an integrated waveform of underwater sounding, communication and guidance based on GSFM signal, characterized in that: The calculation formula of the instantaneous frequency function of each sub-segment signal is as follows: 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 proportional 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.

5. According to claim 4, a method for designing an integrated waveform of underwater sounding, communication and guidance based on GSFM signal, characterized in that: The calculation formula of the instantaneous frequency function of the variant signal is as follows: Among them, f inst_norm (t i ) represents the instantaneous frequency function of the normalized signal, f c Indicates the center frequency entered by the user, f inst (t i ) represents the instantaneous frequency of the signal before normalization.

6. The method for designing an integrated underwater sounding, guiding and conducting waveform based on GSFM signal according to claim 5, characterized in that: The calculation formula of the instantaneous phase function of the signal is as follows: in, represents the instantaneous phase function within the time range corresponding to the i-th sub-segment, f inst_norm (t i ) represents the instantaneous frequency function of the normalized 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.

7. The method for designing an integrated underwater sounding and guiding waveform based on GSFM signal according to claim 6, characterized in that: The time domain mathematical representation of the variant GSFM signal is: 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.

8. The method for designing an integrated underwater sounding and guiding waveform based on GSFM signal according to claim 7, characterized in that: The modulation parameter ρ≥1, when ρ=1, the signal degenerates into an SFM signal.

9. An underwater sounding, communication and guiding integrated waveform system based on GSFM signal, characterized by: It includes 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 1-8.

10. 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 guiding integrated waveform design method based on GSFM signals as described in any one of claims 1-8 when executed.

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