A method and system for sensing in-band interference of standard TT&C signals

Abstract

The application provides a standard TT&C signal in-band interference sensing method and system, comprising the following steps: S1, processing a received signal into spectrum data; S2, screening single tone points in the spectrum data based on a spectrum gradient, and determining single tone interference frequency points and secondary single tone points of the standard TT&C signal; S3, calculating a decision threshold; S4, screening frequency points that may exist in interference in the original spectrum data based on the decision threshold, and determining interference signal frequency points according to spectrum continuity judgment; S5, revising the amplitude values of the secondary single tone points of the standard TT&C signal by using the interference signal frequency points; S6, judging whether single tone interference exists on each single tone point by combining a preset threshold and the symmetry of the secondary single tone points; and S7, obtaining an interference sensing result by comprehensively combining the judgment results of S2, S5 and S6. The application can identify TT&C signal and interference signal frequency points under the condition that only the effective bandwidth of the standard TT&C signal is known.

Description

Technical Field

[0001] This invention relates to the field of interference sensing, and in particular to a method and system for sensing interference within the standard TT&C signal band. Background Technology

[0002] In wireless telemetry and communication systems, signal receiving equipment may face interference in two main categories: intentional interference and unintentional interference. Unintentional interference includes co-channel interference from other communication systems and natural electromagnetic interference. Co-channel interference from other communication systems includes interference from 4G / 5G base stations, low-orbit satellites, and high-orbit satellites, while natural electromagnetic interference includes interference from industrial equipment and lightning. Intentional interference includes relay interference and deliberate interference from jamming aircraft / jamming pods.

[0003] If interference exists in the environment and reaches a certain intensity, it will affect the normal operation of the system. Interference sensing can effectively identify interference in cooperative signal reception, providing input for interference suppression and information on interference conditions for link performance anomaly review.

[0004] Currently, research on interference signal perception mainly focuses on interference perception under different conditions during and outside the silent period of a radio system. During the silent period, there are no cooperative communication signals from the radio system, and only interference signals within the noise need to be considered. During the non-silent period, cooperative communication signals exist, requiring the detection and identification of interference signals from these signals. Interference signal perception during the non-silent period is more difficult than during the silent period. The analysis of interference signals primarily employs time-domain analysis, frequency-domain analysis, and transform-domain analysis, using commonly used methods for single-tone, multi-tone, narrowband, wideband, and frequency-sweeping interference. In the non-silent period, frequency-domain interference signal perception analysis is challenging because the presence of cooperative communication signals often results in spectral aliasing between the interference signals and the cooperative communication signals, complicating the analysis process.

[0005] In the field of aerospace telemetry and control, standard TT&C signals are widely used as a standard practice. Standard TT&C signals are implemented using the "frequency division multiplexing" principle. Multiple subcarriers are used to adjust the angle on a single carrier wave, achieving frequency division multiplexing for multiple signal transmission. Each subcarrier performs a single function, thus enabling multi-functional integration in telemetry and control. The residual carrier component in the signal is used for angle tracking and Doppler frequency shift measurement. Standard TT&C signals have multiple carriers and discrete single-tone spectral lines in their spectrum, resulting in a relatively complex spectral appearance. When interference signals are mixed in, aliasing easily occurs in the spectrum, making in-band interference sensing and analysis difficult.

[0006] Currently, there are three common methods for dealing with non-quiet periods: 1) Modeling cooperative communication signals, storing cooperative communication signal templates, and subtracting the spectrum of cooperative communication signals before interference detection; 2) Using intelligent methods to construct network separators, analyzing the spectra of cooperative communication signals and interference signals, and then analyzing the interference; 3) Designing special processing based on the spectral characteristics of cooperative communication signals. Of these three methods, the first requires preliminary modeling work and also has amplitude matching issues; the second method requires extensive offline training, and the deployment of intelligent algorithms requires computing power, placing certain requirements on the hardware platform used in actual engineering; the third method is only applicable to specific cooperative communication signals, and its scope of application is limited.

[0007] For standard TT&C signals, each of the three methods described above has its own shortcomings. However, considering the amount of prior information required and the complexity of the processing, the third method is simpler and easier to implement. Furthermore, there are currently no interference sensing methods specifically designed based on the characteristics of standard TT&C signals. Therefore, designing an in-band interference sensing method based on the spectral characteristics of standard TT&C signals has significant engineering application implications. Summary of the Invention

[0008] To address the challenges of detecting, identifying, and analyzing in-band interference signals in standard TT&C signals due to their complex in-band spectrum, this paper presents a method and system for sensing in-band interference in standard TT&C signals. Utilizing the characteristics of the left-right symmetry of the in-band spectral envelope and the uniform distribution of single-tone spectral lines in standard TT&C signals, this method enables high-accuracy detection and identification of interference signals, providing support for further interference parameter analysis.

[0009] The first aspect of this invention proposes a standard TT&C signal in-band interference sensing method, comprising:

[0010] Step S1: Downconvert the received signal to a zero intermediate frequency signal, and then perform FFT transformation to obtain the spectrum data;

[0011] Step S2: Based on the spectral gradient, the single-tone points in the spectral data are filtered out, and based on the left and right symmetry of each single-tone point along the center frequency point, it is determined whether there is single-tone interference, and the single-tone interference frequency point and each secondary single-tone point of the standard TT&C signal are determined; wherein, each secondary single-tone point does not include the center main single-tone point;

[0012] Step S3: Determine the decision threshold η3 based on the effective out-of-band and filter edge spectral regions of the TT&C signal;

[0013] Step S4: Based on the decision threshold, filter out the frequency points in the spectrum data in step S1 that may contain interference, and determine whether there is in-band broadband interference and narrowband interference based on the spectrum continuity to obtain the frequency points of the interference signal.

[0014] Step S5: Using the frequency points of the interference signal, revise the amplitude values ​​of each level of the single-tone point of the standard TT&C signal; wherein, each level of single-tone point includes the center main single-tone point;

[0015] Step S6: Combine the preset threshold and the symmetry of each level of single-tone points to determine whether there is single-tone interference on each single-tone point; if multiple single-tone interferences are detected in the band, it is determined to be multi-tone interference;

[0016] Step S7, combining the judgment results of steps S2, S5 and S6, yields the interference perception result.

[0017] Furthermore, in step S2, the method for filtering single audio points is as follows: for frequency point ω n Calculate the amplitude ΔX - =|X(ω) n )|-|X(ω n-1 )|,ΔX + =|X(ω) n )|-|X(ω n+1 If ΔX - ,ΔX + If all frequencies are greater than the decision threshold η0, then frequency points ω are selected. n It is a single audio point.

[0018] Furthermore, in step S2, the specific method for determining whether single-tone interference exists is as follows:

[0019] Step S2.1: Based on the selected single-audio points, calibrate ω. n The frequency point with 0 is the center frequency point. Take the first single-tone point to the left of the center frequency point and calculate the frequency difference between it and the center frequency point; take the first single-tone point to the right of the center frequency point and calculate the frequency difference between it and the center frequency point.

[0020] Step S2.2: If the absolute value of the difference between the two frequency differences is less than the decision threshold η1, then the two single-tone points are marked as undetermined frequency points, and proceed to step S2.3; otherwise, the single-tone point with the smaller frequency difference is marked as a single-tone interference frequency point, and proceed to step S2.4.

[0021] Step S2.3: Select the next single-tone point to the left and right respectively, calculate the frequency difference between the two and the center frequency point, and proceed to step S2.2;

[0022] Step S2.4: Take the next single-tone frequency point away from the center frequency point based on the single-tone interference frequency point, calculate its frequency difference with the center frequency point, and obtain the frequency difference between the other single-tone frequency point that was not calibrated in step S2.2 and the center frequency point, and then proceed to step S2.2.

[0023] Step S2.5: Repeat steps S2.2 to S2.4 until all single-tone points are calibrated;

[0024] Step S2.6: For all calibrated undetermined frequency points, calculate the frequency difference between adjacent single-tone points to obtain the maximum frequency difference. If the absolute value of the difference between the current frequency point and its left adjacent single-tone point, the current frequency point and its right adjacent single-tone point, and the maximum frequency difference is all less than the judgment threshold η2, then the current frequency point is determined to be a single-tone interference frequency point; otherwise, the current frequency point is determined to be a secondary single-tone point of the standard TT&C signal. Repeat step S2.4 until the judgment of all undetermined frequency points is completed.

[0025] Furthermore, in step S3, the decision threshold η3 is calculated as follows:

[0026]

[0027] Where ω m ω is the filter edge frequency. n This refers to the edge frequency of the effective frequency band of the TT&C signal.

[0028] Furthermore, in step S4, the method for determining the interference frequency point is as follows:

[0029] Step S4.1: Compare the amplitude of each frequency point in the spectrum data in step S1 with the decision threshold η3. If it is greater than the threshold, then select the frequency point as a re-screening undetermined frequency point.

[0030] Step S4.2: Cluster all the frequency points to be determined by rescreening; where the frequency points with continuous and uninterrupted frequencies are one cluster;

[0031] Step S4.3: If the cluster does not contain any of the secondary single-tone points of the standard TT&C signal, then the cluster is an interference signal frequency point; if the cluster contains any of the secondary single-tone points of the standard TT&C signal, then proceed to step S4.4.

[0032] Step S4.4: Check if there are clusters at the single-tone point positions symmetrical along the zero intermediate frequency. If not, determine that the current cluster is an interference signal frequency point. If there are clusters, check the symmetry conditions of the spectral envelopes of the two clusters and the symmetry conditions of the spectral envelope of the cluster itself. If the spectral envelopes of the two clusters do not meet the symmetry conditions, the cluster that does not meet the symmetry conditions of its own spectral envelope is an interference signal frequency point.

[0033] Step S4.5: If the spectral width of the interference signal frequency cluster is less than 10% of the effective frequency band of the TT&C signal, it is narrowband interference; if it is greater than 10% of the effective frequency band of the TT&C signal, it is broadband interference.

[0034] Furthermore, in step S4.4, the symmetry condition check process of the spectral envelopes of the two clusters is as follows: based on the symmetrical alignment of the single-tone points contained in the clusters, the correlation coefficient of the spectral envelopes of the two clusters is calculated. If the correlation coefficient value is greater than the judgment threshold η4, then the two clusters satisfy the symmetry condition.

[0035] Furthermore, in step S4.4, the symmetry condition check process of the cluster's own spectral envelope is as follows: the correlation coefficient of the left and right spectral envelopes is calculated based on the single audio points contained in the cluster. If the correlation coefficient value is greater than the judgment threshold η4, then the cluster's own spectral envelope satisfies the symmetry condition.

[0036] Furthermore, in step S5, the revised method is as follows: calculate the average amplitude value of the frequency cluster of the interference signal containing a single audio point, and deduct the component of the average amplitude value from the amplitude value of the single audio point.

[0037] Furthermore, in step S6, the method for determining whether there is single-tone interference at each single-tone point includes:

[0038] Calculate the amplitude difference between single-tone points symmetrical to the left and right of the zero center frequency. If the difference is greater than the judgment threshold η5, then there is single-tone interference at the single-tone point with the larger amplitude value.

[0039] For the zero center frequency point, the amplitude is compared with the nearby single-tone frequency point without single-tone interference. If the amplitude ratio is greater than the judgment threshold η6, then there is single-tone interference at the zero center frequency point.

[0040] A second aspect of this invention provides a standard TT&C signal in-band interference sensing system, comprising:

[0041] The FFT module is used to transform time-domain digital signals into frequency-domain data and output them to the single-tone point filtering module and the decision threshold η3 calculation module.

[0042] The single-tone point filtering module is used to filter out single-tone points from the noise floor and signal of the spectrum data and output them to the signal and interference single-tone point calibration module.

[0043] The signal and interference single-tone point calibration module is used to identify the signal's secondary single-tone points and interference single-tone points from the selected single-tone points, output the interference single-tone points to the interference perception result processing module, and output the signal's secondary single-tone points to the signal single-tone point amplitude correction module and the broadband and narrowband interference determination module.

[0044] The decision threshold η3 calculation module is used to calculate the decision threshold and output the calculated threshold to the interference frequency point screening module.

[0045] The interference frequency screening module is used to determine possible interference frequency points from the received signal spectrum based on the decision threshold η3, and output the results to the broadband and narrowband interference determination module.

[0046] The broadband and narrowband interference determination module is used to cluster possible interference frequency points to determine whether they are interference, as well as the broadband and narrowband types of interference, and output the results to the signal single-tone point amplitude correction module and the interference perception result processing module.

[0047] The single-tone amplitude correction module is used to correct the impact of broadband and narrowband interference on the amplitude value of the single-tone point of the signal, so as to facilitate subsequent processing. The corrected amplitude result is output to the single-tone interference determination module at each single-tone point of the signal.

[0048] The single-tone interference determination module at each single-tone point of the signal is used to determine whether single-tone interference exists at each single-tone point of the signal, and outputs the determination result to the interference perception result processing module; and

[0049] The interference perception result processing module is used to process the interference decision outputs of the signal and interference single-tone point calibration module, the broadband and narrowband interference determination module, and the single-tone interference determination module at each single-tone point of the signal, and output the final perception result.

[0050] Compared with existing technologies, the beneficial effects of adopting the above technical solution are as follows:

[0051] 1) This invention utilizes the spectral characteristics of the standard TT&C signal to identify the frequency points of the TT&C signal and the interference signal, even when only the effective bandwidth of the standard TT&C signal is known.

[0052] 2) The method proposed in this invention solves the problems of interference detection, type identification, and interference signal bandwidth estimation in the complex spectrum band of standard TT&C signals.

[0053] 3) The present invention designs a standard TT&C signal in-band interference sensing system, which decomposes the method process and integrates a software implementation scheme for standard TT&C signal in-band interference sensing using basic sub-modules. Attached Figure Description

[0054] Figure 1 This is a flowchart of the standard TT&C signal in-band interference sensing method proposed in this invention.

[0055] Figure 2 This is a schematic diagram of the received signal spectrum in one embodiment of the present invention.

[0056] Figure 3 This is a block diagram of a standard TT&C signal in-band interference sensing system proposed in one embodiment of the present invention.

[0057] Figure 4 for Figure 3 Block diagram of the single-audio point filtering module in the illustrated embodiment.

[0058] Figure 5 for Figure 3 The block diagram of the signal and interference single-tone point calibration module in the embodiment shown.

[0059] Figure 6 for Figure 3 Block diagram of the broadband-narrowband interference determination module in the illustrated embodiment.

[0060] Figure 7 for Figure 3 Block diagram of the single-tone amplitude correction module in the illustrated embodiment.

[0061] Figure 8 for Figure 3 The block diagram of the single-tone interference determination module at each single-tone point of the signal in the embodiment shown. Detailed Implementation

[0062] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar modules or modules having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, the embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0063] Example 1

[0064] To address the challenges of detecting, identifying, and analyzing in-band interference signals due to the complex spectral characteristics of standard TT&C signals, this embodiment proposes an in-band interference sensing method for standard TT&C signals. This method is applied to the baseband processing of standard TT&C signals in aerospace telemetry and control systems. Figure 1 As shown, it specifically includes:

[0065] Step S1: Downconvert the received signal to a zero intermediate frequency signal according to the frequency of the telemetry and communication center, and then perform FFT transformation to obtain the spectrum data X. ω =[X(ω0),X(ω1),…,X(ω N-1 )];

[0066] Step S2: Calculate the frequency point ω n Spectral gradient ΔX at the location - =|X(ω) n )|-|X(ω n-1 ),ΔX + =|X(ω) n )|-|X(ωn+1 If ΔX - ,ΔX + If all frequencies are greater than the decision threshold η0, then frequency points ω are selected. n For a single audio point, the frequency value ω n and the spectral amplitude at the frequency point |X(ω) n )| Add the sequence ω respectively tp and After filtering the single-tone points in the spectrum, the final ω is obtained. tp and Simultaneously generate a label sequence L lable =0. Based on ω tp The presence of single-tone interference is determined by assessing the left-right symmetry of each single-tone point along the center frequency. This identifies the frequency of the single-tone interference and the positions of the secondary single-tone points of the standard TT&C signal. The secondary single-tone points of the standard TT&C signal are those excluding the central primary single-tone point. The specific steps are as follows:

[0067] Step S2.1, Calibration sequence ω tp Frequency points with a median value of 0 Let j be the center frequency. - =1,j + =1,l i =1;

[0068] Step S2.2, Calculation and

[0069] Step S2.3, if Then frequency point and Corresponding label assignment Let j - =j - +1, j + =j + +1, proceed to step S2.6;

[0070] Step S2.4, if and Then frequency point Corresponding label assignment Let j + =j + +1, proceed to step S2.6;

[0071] Step S2.5, if and Then frequency point Corresponding label assignment Let j - =j -+1, proceed to step S2.6;

[0072] Step S2.6, if ij - ≥1 and i+j + ≤|ω tp If the condition is met, return to step S2.2; otherwise, proceed to step S2.7.

[0073] Step S2.7, L lable All tags with a value of 0 are assigned the value -1.

[0074] Step S2.8, L lable All frequency points with a label value of 1 are sequentially extracted to form a new sequence ω. tp_lable＝1 and

[0075] Step S2.9: Let j = 1;

[0076] Step S2.10, Calculation If j <|ω tp_lable＝1 If |-1, let j = j+1, and repeat this step; otherwise, proceed to the next step.

[0077] Step S2.11: Calculate max{Δω} tp_lable＝1 Let j = 1;

[0078] Step S2.12, when j = 1, if Then let In L lable The label value in the text is changed to -1; when 1≤j<|ω tp_lable＝1 When |-1, if and Then let In L lable The label value in the text is changed to -1, j = j + 1, and this step is repeated; when j = |ω tp_lable＝1 When |-1, if Then let In L lable The label value in the text is changed to -1;

[0079] Step S2.13, L lable The frequency point with a label value of -1 is the single-tone interference frequency point, L lable The frequency points corresponding to the label value of 1 are the secondary single-tone points of the standard TT&C signal.

[0080] Step S3: Obtain the effective frequency band edge frequency of the TT&C signal as ω through parameter configuration. n The filter edge frequency is ω m Calculate the decision threshold

[0081] Step S4: Based on the decision threshold, filter out the frequency points in the spectrum data from step S1 that may contain interference, and determine whether there is in-band broadband interference and narrowband interference based on the spectrum continuity to obtain the frequency points of the interference signal. The specific steps are as follows:

[0082] Step S4.1, based on the original spectrum X ω =[X(ω0),X(ω1),…,X(ω N-1 ]], perform judgment and clustering processing, let n=0, the number of clusters k=1, and the frequency set of the kth cluster be Φ k =φ, continuous counting count = 0;

[0083] Step S4.2, if |X(ω) n If )|>η3 and count≤3, then let Φ k =Φ k ∪{ω n}, n = n + 1, count = 0, duplicate checks;

[0084] Step S4.3, if |X(ω) n If |>η3 and count>3, then k=k+1, let Φ k =Φ k ∪{ω n}, n = n + 1, count = 0, duplicate checks;

[0085] Step S4.4, if |X(ω) n If | ≤ η3, then count = count + 1, n = n + 1, and the condition is repeated.

[0086] Step S4.5: If n = N, then let K = k, and then let k = 1, to process and analyze each cluster. First, generate a label sequence L′ corresponding to the cluster. lable =0;

[0087] Step S4.6, Judgment Then cluster Φ k Assign the value l′ to the frequency of the interference signal. k =1, let k = k+1, and repeat the judgment;

[0088] Step S4.7, Judgment and Then cluster Φ k Assign the value l′ to the frequency of the interference signal. k =1, let k = k+1, and repeat the judgment;

[0089] Step S4.8, Judgment and Then let judge Regarding the center frequency Does clustering exist at the symmetrical point? If not, then the clustering Φ k Assign the value l′ to the frequency of the interference signal. k =1, let k = k+1, repeat the judgment; if it exists, then judge the cluster Φ. k Envelope about The symmetry of the cluster Φ; if it is asymmetrical, then the cluster Φ k Assign the value l′ to the frequency of the interference signal. k =1, let k = k+1, and repeat the judgment;

[0090] Step S4.9, Tag Sequence L′ lable The cluster Φ corresponding to all label values ​​of 1 k_lable＝1 For interference, calculate the bandwidth of each interference spectrum. if This is narrowband interference; if This is broadband interference.

[0091] Step S5, based on the determined Φ k_lable＝1 Interference signal frequency points, corresponding to the single-tone points ω of each level of the standard TT&C signal. tp_lable＝1 Amplitude The revisions are as follows: The standard TT&C signal's single-tone points at each stage now include the central master single-tone point.

[0092] Step S5.1: Let k = 1;

[0093] Step S5.2, Calculation

[0094]

[0095] Step S5.3, let k = k + 1, return to step S5.2.

[0096] Step S6: Based on the decision thresholds η5 and η6 and the symmetry of each single-tone point, determine whether there is single-tone interference at each single-tone point. The specific steps are as follows:

[0097] Step S6.1: Based on the standard TT&C signal, the single-tone points ω at each level tp_lable＝1 Amplitude Process and calibrate ω tp Frequency points with a median value of 0 Let j = 1, which is the center frequency.

[0098] Step S6.2, Judgment like Then frequency point The corresponding label is assigned the value l i-j =-1, if Then frequency point The corresponding label is assigned the value l i+j =-1, j=j+1, duplicate judgment;

[0099] Step S6.3, Judgment Then frequency point The corresponding label is assigned the value l i =-1;

[0100] Step S6.4, if L lable If the number of labels with a value of -1 is greater than 1, it is determined to be polyphonic interference.

[0101] Step S7: Summarize the judgment results of steps S2, S5 and S6 to obtain the interference perception result.

[0102] It should be noted that the order of steps S1 to S7 in the interference sensing method provided in this embodiment is not completely fixed and can be adjusted according to actual needs. For example, step S3 can be executed first, followed by step S2.

[0103] The following is based on Figure 2 Taking the received signal spectrum shown as an example, the implementation process of the above interference sensing method will be further explained. Specifically, it is as follows:

[0104] Step 201: Calculate the spectral gradient at each frequency point and determine ω. tp ={ω2, ω5, ω9, ω 11 ω 13 ω 14}and Simultaneously generate a label sequence L lable =0;

[0105] Step 202, Calibrate ω tp Frequency points with a median value of 0 Let l3 = 1, which is the center frequency.

[0106] Step 203, Calculation and

[0107] Step 204, |Δω - 1-Δω + 1|<η1, frequency point and The corresponding labels are assigned the values ​​l2=1 and l4=1;

[0108] Step 205, Calculation and

[0109] Step 206, |Δω - 2-Δω +2|>η1 and Δω - 2>Δω + 2. Frequency The corresponding label is assigned the value l5 = -1;

[0110] Step 205, Calculation

[0111] Step 206, |Δω - 2-Δω + 3|<η1, frequency point and The corresponding labels are assigned the values ​​l1 = 1 and l6 = 1;

[0112] Step 207, L lable All frequency points with a label value of 1 are sequentially extracted to form a new sequence ω. tp_lable＝1 ={ω2, ω5, ω9, ω 11 ω 14}and

[0113] Step 208: Calculate Δω tp_lable＝1 ={ω5-ω2, ω9-ω5, ω 11 -ω9,ω 14 -ω 11};

[0114] Step 209: Calculate max{Δω} tp_lable＝1}=ω 11 -ω9;

[0115] Step 210, Δω is calculated. tp_lable＝1 All elements in the max{Δω tp_lable＝1 The differences between the values ​​are all less than the threshold.

[0116] Step 211, L lable The frequency point with a label value of -1 For single-tone interference frequency, L lable The frequency point ω corresponding to a middle label value of 1 tp_lable＝1 ={ω2, ω5, ω9, ω 11 ω 14} represents the single-tone points of each secondary stage of the standard TT&C signal.

[0117] Step 212: Based on the original spectrum and threshold η3, perform judgment and clustering processing to obtain 4 clusters, namely: Φ 1 ={ω|ω1≤ω≤ω3}, Φ 2 ={ω|ω4≤ω≤ω6}, Φ 3 ={ω|ω7≤ω≤ω8}, Φ 4 ={ω|ω 10 ≤ω≤ω12 Generate a label sequence L′ corresponding to the 4 clusters. lable =0.

[0118] Step 214, Determine Φ 1 ∩{ω2, ω5, ω9, ω 11 ω 14}=ω2, and |Φ 1 ∩{ω2, ω5, ω9, ω 11 ω 14 If} = 1, then let Determine the point ω2 symmetrical about the center frequency ω9. 14 If there is no cluster at a given location, then the cluster Φ is present. 1 ={ω|ω1≤ω≤ω3} is the frequency point of the interference signal, and is assigned the value l′1=1;

[0119] Step 215, Determine Φ 2 ∩{ω2, ω5, ω9, ω 11 ω 14}=ω5, and |Φ 2 ∩{ω2, ω5, ω9, ω 11 ω 14 If} = 1, then let Determine the symmetrical position of ω5 about the center frequency ω9. 11 There are clusters Φ 4 ={ω|ω 10 ≤ω≤ω 12}, further determine clustering Φ 2 The envelope of {ω|ω4≤ω≤ω6} is symmetrical about ω5.

[0120] Step 216, Determine Φ 3 ∩{ω2, ω5, ω9, ω 11 ω 14 If}=φ, then the clustering is Φ 3 ={ω|ω7≤ω≤ω8} is the frequency point of the interference signal, and is assigned the value l′3=1;

[0121] Step 217, Determine Φ 4 ∩{ω2, ω5, ω9, ω 11 ω 14}=ω 11 And |Φ 4 ∩{ω2, ω5, ω9, ω 11 ω 14 If} = 1, then let Determine ω 11 There is a cluster Φ at ω5, which is symmetrical about the center frequency ω9. 2 ={ω|ω4≤ω≤ω6}, further determine clustering Φ 4 ={ω|ω10 ≤ω≤ω 12 The envelope of} with respect to ω 11 Symmetrical;

[0122] Step 218, Tag Sequence L′ lable The cluster Φ corresponding to all label values ​​of 1 1 ={ω|ω1≤ω≤ω3} and Φ 3 ={ω|ω7≤ω≤ω8} represents interference; calculate Φ 1 For broadband interference; calculation Φ 3 This is narrowband interference.

[0123] Step 219, Φ 1 ={ω|ω1≤ω≤ω3} contains a single-tone point of the standard TT&C signal. calculate

[0124]

[0125] Step 220, Order

[0126] Step 221, Calibrate ω tp Frequency points with a median value of 0 As the center frequency, determine

[0127]

[0128] Step 222, Judgment

[0129]

[0130] Step 223, the interference sensing result is ω 13 Single-tone interference, Φ 1 ={ω|ω1≤ω≤ω3} broadband interference, Φ 3 ={ω|ω7≤ω≤ω8} Narrowband interference.

[0131] As can be seen, the interference sensing method proposed in this invention utilizes the spectral characteristics of the standard TT&C signal to identify the frequency points of the TT&C signal and the interference signal, even when only the effective bandwidth of the standard TT&C signal is known.

[0132] Example 2

[0133] This embodiment provides a standard TT&C signal in-band interference sensing system, applied to baseband signal processing in aerospace telemetry and control stations, such as... Figure 3As shown, the standard TT&C signal in-band interference sensing system includes: an FFT module 301, a single-tone point screening module 302, a signal and interference single-tone point calibration module 303, a decision threshold η3 calculation module 304, an interference frequency point initial screening module 305, a broadband and narrowband interference determination module 306, a signal single-tone point amplitude revision module 307, a single-tone interference determination module for each single-tone point of the signal 308, and an interference sensing result processing module 309.

[0134] FFT module 301 is used to transform time-domain digital signals into frequency-domain data and output them to single-audio point filtering module 302 and decision threshold η3 calculation module 304.

[0135] The single-tone point filtering module 302 is used to filter out single-tone points from the noise floor and signal of the spectrum data and output them to the signal and interference single-tone point calibration module 303. The calculation method used is to make a decision based on the change of the gradient of the spectrum data sequence.

[0136] The signal and interference single-tone point calibration module 303 is used to identify the single-tone points of the signal and the single-tone points of the interference from the selected single-tone points, output the interference single-tone points to the interference perception result processing module 309, and output each secondary single-tone point of the signal to the signal single-tone point amplitude correction module 307 and the broadband and narrowband interference determination module 306.

[0137] The decision threshold η3 calculation module 304 is used to calculate the decision threshold and output the calculated threshold to the interference frequency point screening module 305.

[0138] The interference frequency screening module 305 is used to determine the possible interference frequencies from the received signal spectrum based on the decision threshold η3, and output the results to the broadband and narrowband interference determination module 306.

[0139] The broadband and narrowband interference determination module 306 is used to further cluster and determine whether possible interference frequency points are interference, as well as the broadband and narrowband types of interference, and output the results to the signal single-tone point amplitude correction module 307 and the interference perception result processing module 309.

[0140] The single-tone amplitude correction module 307 is used to correct the impact of broadband and narrowband interference on the amplitude value at the single-tone point of the signal, so as to facilitate subsequent processing. The corrected amplitude result is output to the single-tone interference determination module 308 at each single-tone point of the signal.

[0141] The single-tone interference determination module 308 at each single-tone point of the signal is used to determine whether there is single-tone interference at each single-tone point of the signal, and outputs the determination result to the interference perception result processing module 309.

[0142] The interference perception result processing module 309 is used to process the interference decision outputs of the signal and interference single-tone point calibration module, the broadband and narrowband interference determination module, and the single-tone interference determination module at each single-tone point of the signal, and output the final perception result.

[0143] Please refer to Figure 4 In this embodiment, the single audio point filtering module 302 includes: a sequence gradient calculation unit 3021 and a decision unit 3022;

[0144] The sequence gradient calculation unit 3021 is used to calculate the left and right gradient values ​​at each frequency point;

[0145] The decision unit 3022 is used to compare the gradient value with the decision threshold and determine whether it is a single audio point.

[0146] Please refer to Figure 5 In this embodiment, the signal and interference single-tone point calibration module 303 includes: an asymmetric single-tone interference screening unit 3031 and a symmetric single-tone interference determination unit 3032.

[0147] The asymmetric single-tone interference screening unit 3031 is used to take points from the left and right of the center frequency point after screening the single-tone points, calculate the frequency difference with the center frequency point, and judge the single-tone interference based on the difference between the left and right frequency differences.

[0148] The symmetrical single-tone interference determination unit 3032 is used to calculate the maximum value of the frequency difference between adjacent single-tone points for all undetermined single-tone points, and determine the single-tone interference frequency point based on the frequency difference.

[0149] Please refer to Figure 6 In this embodiment, the broadband-narrowband interference determination module 306 includes: a frequency point clustering unit 3061, a signal single-tone point inclusion determination unit 3062, a zero intermediate frequency symmetry checking unit 3063, a cluster envelope self-symmetry checking unit 3064, a cluster spectrum envelope correlation coefficient calculation unit 3065, and a broadband-narrowband type determination unit 3066.

[0150] The frequency clustering unit 3061 is used to process frequency points and divide them into independent frequency clusters;

[0151] The signal single-tone point inclusion determination unit 3062 is used to determine whether a cluster contains single-tone points of the signal at each level, and to determine clusters that do not contain single-tone points of the signal as interference;

[0152] The zero-IF symmetry checking unit 3063 is used to check whether there are clusters that are symmetrical along the zero-IF on the left and right sides, and to determine that clusters that do not have corresponding symmetrical clusters are interference.

[0153] Cluster envelope self-symmetry checking unit 3064 is used to check whether the left and right sides of the cluster spectrum envelope are symmetrical about the center, and to determine the cluster that does not satisfy self-symmetry among the two clusters that satisfy zero intermediate frequency symmetry as interference;

[0154] Clustered spectral envelope correlation coefficient calculation unit 3065 is used to calculate the correlation between two spectral envelope sequences as an indicator of symmetry checking.

[0155] The broadband / narrowband type determination unit 3066 is used to compare the bandwidth of each interference cluster with that of the standard TT&C signal to determine whether the interference type is narrowband or broadband.

[0156] Please refer to Figure 7 In this embodiment, the single-tone amplitude correction module 307 includes: an average amplitude calculation unit 3071 and a single-tone amplitude deduction unit 3072.

[0157] The average amplitude calculation unit 3071 is used to calculate the average amplitude value of the frequency cluster of interference signals containing single-tone points.

[0158] The single-tone point amplitude subtraction unit 3072 is used to subtract the average amplitude value component from the amplitude of a single-tone point.

[0159] Please refer to Figure 8 In this embodiment, the single-tone interference determination module 308 at each single-tone point of the signal includes: a zero-center symmetrical single-tone interference determination unit 3081 and a center frequency single-tone interference determination unit 3082.

[0160] The zero-center symmetrical single-tone interference determination unit 3081 is used to calculate the amplitude difference between single-tone points symmetrical about the left and right sides of the zero center frequency point, and to determine single-tone interference based on the amplitude difference.

[0161] The center frequency single-tone interference determination unit 3082 is used to compare the amplitude of the zero center frequency point with the adjacent single-tone point without single-tone interference to determine whether there is single-tone interference.

[0162] This embodiment demonstrates the implementation of the method of the present invention into system modules, representing a preferred system implementation of a standard TT&C signal in-band interference sensing method.

[0163] It should be noted that, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances. The accompanying drawings in the embodiments are used to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0164] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for sensing in-band interference of a standard TT&C signal, characterized in that, include: Step S1: Downconvert the received signal to a zero intermediate frequency signal, and then perform FFT transformation to obtain the spectrum data. ； Step S2: Based on the spectral gradient, the single-tone points in the spectral data are filtered out, and based on the left and right symmetry of each single-tone point along the center frequency point, it is determined whether there is single-tone interference, and the single-tone interference frequency point and each secondary single-tone point of the standard TT&C signal are determined. Step S3: Determine the decision threshold based on the effective out-of-band and filter edge spectral regions of the TT&C signal. ; Step S4: Based on the decision threshold The frequency points that may be interfering in the spectrum data in step S1 are screened out, and the presence of in-band broadband interference and narrowband interference is determined based on the spectrum continuity to obtain the frequency points of the interfering signal. Step S5: Using the frequency points of the interference signal, revise the amplitude values ​​of each level of the single-tone point of the standard TT&C signal; Step S6: Combine the preset threshold and the symmetry of each level of single-tone points to determine whether there is single-tone interference on each single-tone point; if multiple single-tone interferences are detected in the band, it is determined to be multi-tone interference; Step S7: Combine the judgment results of steps S2, S5 and S6 to obtain the interference perception result. In step S2, the method for filtering single audio points is as follows: for frequency points Calculate the amplitude ,if All are greater than the judgment threshold Then the frequency points are selected. For a single audio point; In step S3, the decision threshold is determined. The calculation method is as follows: in, For the filter edge frequency, This refers to the edge frequency of the effective frequency band of the TT&C signal.

2. The standard TT&C signal in-band interference sensing method according to claim 1, characterized in that, In step S2, the specific method for determining whether single-tone interference exists is as follows: Step S2.1: Based on the selected single audio points, calibrate. The frequency point is taken as the center frequency point. The first single-tone point to the left of the center frequency point is taken, and the frequency difference between it and the center frequency point is calculated. The first single-tone point to the right of the center frequency point is taken, and the frequency difference between it and the center frequency point is calculated. Step S2.2: If the absolute value of the difference between the two frequency differences is less than the decision threshold... If the two single-tone points are marked as undetermined frequency points, proceed to step S2.3; otherwise, mark the single-tone point with the smaller frequency difference as the single-tone interference frequency point. Step S2.3: Select the next single-tone point to the left and right respectively, calculate the frequency difference between the two and the center frequency point, and proceed to step S2.2; Step S2.4: Take the next single-tone frequency point away from the center frequency point based on the single-tone interference frequency point, calculate its frequency difference with the center frequency point, and obtain the frequency difference between the other single-tone frequency point that was not calibrated in step S2.2 and the center frequency point, and then proceed to step S2.

2. Step S2.5: Repeat steps S2.2 to S2.4 until all single-tone points are calibrated; Step S2.6: For all calibrated undetermined frequency points, calculate the frequency difference between adjacent single-tone points to obtain the maximum frequency difference. If the absolute value of the difference between the current frequency point and its left adjacent single-tone point, the frequency difference between the current frequency point and its right adjacent single-tone point, and the maximum frequency difference are all less than the judgment threshold, then... If the current frequency point is determined to be a single-tone interference frequency point, then the current frequency point is determined to be a single-tone frequency point of each secondary of the standard TT&C signal; repeat step S2.4 until the determination of all undetermined frequency points is completed.

3. The standard TT&C signal in-band interference sensing method according to claim 1, characterized in that, In step S4, the method for determining the interference frequency point is as follows: Step S4.1: Compare the amplitude of each frequency point in the spectrum data from step S1 with the decision threshold. The comparison is performed, and if the value exceeds the threshold, the frequency point is selected as a candidate frequency point for re-screening. Step S4.2: Cluster all the frequency points to be determined by rescreening; where the frequency points with continuous and uninterrupted frequency are one cluster; Step S4.3: If the cluster does not contain any of the secondary single-tone points of the standard TT&C signal, then the cluster is an interference signal frequency point; if the cluster contains any of the secondary single-tone points of the standard TT&C signal, then proceed to step S4.

4. Step S4.4: Check if there are clusters at the single-tone point positions symmetrical along the zero intermediate frequency. If not, determine that the current cluster is an interference signal frequency point. If there are clusters, check the symmetry conditions of the spectral envelopes of the two clusters and the symmetry conditions of the spectral envelope of the cluster itself. If the spectral envelopes of the two clusters do not meet the symmetry conditions, the cluster that does not meet the symmetry conditions of its own spectral envelope is an interference signal frequency point. Step S4.5: If the spectral width of the interference signal frequency cluster is less than 10% of the effective frequency band of the TT&C signal, it is narrowband interference; if it is greater than 10% of the effective frequency band of the TT&C signal, it is broadband interference.

4. The standard TT&C signal in-band interference sensing method according to claim 3, characterized in that, In step S4.4, the symmetry condition check process for the spectral envelopes of the two clusters is as follows: based on the symmetrical alignment of the single-tone points contained in the clusters, the correlation coefficient of the spectral envelopes of the two clusters is calculated. If the correlation coefficient value is greater than the judgment threshold... If the two clusters satisfy the symmetry condition, then the two clusters satisfy the symmetry condition.

5. The standard TT&C signal in-band interference sensing method according to claim 3, characterized in that, In step S4.4, the symmetry condition check process of the cluster's own spectral envelope is as follows: the correlation coefficient of the left and right spectral envelopes is calculated based on the single audio points contained in the cluster. If the correlation coefficient value is greater than the judgment threshold... If the spectral envelope of the cluster itself satisfies the symmetry condition, then the correlation coefficient of the spectral envelope is calculated by aligning the cluster correlation sequences by padding with zeros.

6. The standard TT&C signal in-band interference sensing method according to claim 1, characterized in that, In step S5, the revision method is as follows: calculate the average amplitude value of the frequency cluster of the interference signal containing a single audio point, and deduct the component of the average amplitude value from the amplitude value of the single audio point. The calculation of the spectral envelope correlation coefficient is achieved by aligning the cluster correlation sequence with zero padding.

7. The standard TT&C signal in-band interference sensing method according to claim 1, characterized in that, In step S6, the method for determining whether there is single-tone interference at each single-tone point includes: Calculate the amplitude difference between single-tone points symmetrically positioned to the left and right of the zero center frequency. If the difference is greater than the judgment threshold... Then, at the single-tone point with a larger amplitude value, there is single-tone interference; For the zero center frequency, the amplitude is compared with that of a nearby single-tone frequency without single-tone interference. If the amplitude ratio is greater than the judgment threshold... Then there is single-tone interference at the zero center frequency point.

8. A standard TT&C signal in-band interference sensing system, characterized in that, Based on the standard TT&C signal in-band interference sensing method according to any one of claims 1 to 7, it includes: The FFT module transforms time-domain digital signals into frequency-domain data and outputs the results to the single-tone point filtering module and decision threshold. Calculation module; The single-tone point filtering module is used to filter out single-tone points from the noise floor and signal of the spectrum data and output them to the signal and interference single-tone point calibration module. The signal and interference single-tone point calibration module is used to identify the signal's secondary single-tone points and interference single-tone points from the selected single-tone points, output the interference single-tone points to the interference perception result processing module, and output the signal's secondary single-tone points to the signal single-tone point amplitude correction module and the broadband and narrowband interference determination module. Judgment threshold The calculation module is used to calculate the decision threshold and output the calculated threshold to the interference frequency screening module. The interference frequency screening module is used to select interference frequencies from the received signal spectrum based on a decision threshold. The system identifies possible interference frequencies and outputs the results to the broadband and narrowband interference determination module. The broadband and narrowband interference determination module is used to cluster possible interference frequency points to determine whether they are interference, as well as the broadband and narrowband types of interference, and output the results to the signal single-tone point amplitude correction module and the interference perception result processing module. The single-tone amplitude correction module is used to correct the impact of broadband and narrowband interference on the amplitude value of the single-tone point of the signal, so as to facilitate subsequent processing. The corrected amplitude result is output to the single-tone interference determination module at each single-tone point of the signal. The single-tone interference determination module at each single-tone point of the signal is used to determine whether single-tone interference exists at each single-tone point of the signal, and outputs the determination result to the interference perception result processing module; and The interference perception result processing module is used to process the interference decision outputs of the signal and interference single-tone point calibration module, the broadband and narrowband interference determination module, and the single-tone interference determination module at each single-tone point of the signal, and output the final perception result.

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