A method for identifying satellite signal VSAT network stations

Abstract

The present invention discloses a satellite signal VSAT network station identification method, S1: receiving a target signal through an antenna, and processing the signal to obtain a timing synchronization signal; S2: taking the timing synchronization signal as input, based on a characteristic codeword sequence and its insertion structure, matching and identifying the type of the target signal VSAT network station. Since the network station identification is performed in the timing synchronization stage, the timing synchronization signal itself has a certain frequency offset and phase offset. Through the cross-correlation operation between the timing synchronization signal and the characteristic codeword sequence, the characteristic codeword sequence matching of different starting points is covered, so there is no need to consider the influence of the characteristic codeword sequence on the matching identification due to different starting points. The identification process does not perform carrier recovery (demodulation) on the signal, so there is no need to consider the phase ambiguity problem caused by signal demodulation. The identification task can be completed only after the timing synchronization is completed, thereby greatly simplifying the complexity of the identification algorithm and improving the identification efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of satellite signal monitoring, in particular to a satellite signal VSAT network station identification method. Background Art

[0002] With the development of VSAT satellite communication system technology, the communication frequency band is wider, and the channel allocation and networking style are more flexible. In addition to traditional fixed stations, it is also more and more widely used in mobile platforms such as vehicles, ships, warships, and aircraft. In order to quickly detect and identify the target network signal, it is necessary to measure the modulation and coding parameters of the target signal and the type of network it belongs to. Therefore, it can quickly identify the network station to which the signal belongs, which has great engineering practical significance for signal monitoring.

[0003] At present, most VSAT network station identification technologies are based on processing satellite signal demodulation data. Since phase recovery will introduce uncertain phase ambiguity, the identification in the demodulation stage needs to consider issues such as phase rotation angle, clockwise and counterclockwise rotation mapping, and alignment of the identification codeword starting point, which increases the difficulty and time of identification. At the same time, when the signal-to-noise ratio of the received signal is low, traditional technologies will not be able to complete identification because the demodulation synchronization cannot be locked or the demodulation bit error rate is too high. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a satellite signal VSAT network station identification method.

[0005] The object of the present invention is achieved by the following technical solution: A satellite signal VSAT network station identification method comprises the following steps:

[0006] S1: Receive the target signal through the antenna and process the signal to obtain the timing synchronization signal r s ;

[0007] S2: with timing synchronization signal r s As input, the VSAT network station type matching and identification are performed on the target signal based on the feature codeword sequence and its insertion structure.

[0008] Preferably, in step S1, the target signal is first subjected to frequency conversion filtering, carrier frequency estimation and rate estimation to obtain a zero intermediate frequency signal, and then subjected to matched filtering and clock recovery to obtain a timing synchronization signal.

[0009] Preferably, the mathematical model of the timing synchronization signal is:

[0010]

[0011] in, is the kth symbol in the received signal, A is the symbol waveform amplitude, Δω is the frequency deviation, T is the symbol duration, is the phase deviation, and n(k) is the Gaussian white noise with power spectral density n0.

[0012] Preferably, step S2 further includes the following steps:

[0013] S21: The feature code word sequences corresponding to different VSAT network station types are grouped into a sequence set to form a feature code word sequence matching library.

[0014] 1≤i≤n,1≤j≤m;

[0015] in, is the jth codeword in the characteristic codeword sequence corresponding to the i-th VSAT network station, n is the number of VSAT network station types, and m is the length of the characteristic codeword sequence corresponding to the VSAT network station;

[0016] S22: The feature codeword sequence b corresponding to the i-th VSAT network station i , according to the modulation style corresponding to the target signal, it is mapped into the modulation sequence cs i ;

[0017] S23: Modulation sequence cs i Interpolate according to the insertion structure of the characteristic codeword sequence to obtain a new characteristic codeword modulation sequence cs2 i ;

[0018] S24: cs2 i Multiply it with its delayed conjugate sequence to get the characteristic codeword modulation differential sequence d_cs2 i , Where M is the characteristic codeword modulation sequence cs2 i The length of , conj() is to take the conjugate;

[0019] The timing synchronization signal r s Multiply it with its delayed conjugate sequence to get the timing synchronization signal differential sequence d_r s ,

[0020]

[0021] Where N is the timing synchronization signal r s The length of , conj() means taking the conjugate;

[0022] S25: Modulate the differential sequence d_cs2 according to the characteristic code word i Differential sequence d_r with timing synchronization signal s Get the relevant modulo sequence,

[0023]

[0024] Where x is the timing synchronization signal differential sequence d_r s , y is the characteristic codeword modulation differential sequence d_cs2 i ;

[0025] S26: Identify the type of VSAT network station.

[0026] Preferably, step S22 further includes the following steps:

[0027] S22.1: Convert the binary sequence b i Group and map symbols according to the rules to get the symbol sequence s i ;

[0028] S22.2: The symbol sequence s after symbol mapping i , modulate according to the modulation style corresponding to the target signal, and obtain the symbol modulation sequence cs i .

[0029] Preferably, in step S23, the interpolation process specifically includes:

[0030] When the signature codeword sequence is inserted in a centralized manner, the modulation sequence cs i No processing, cs2 i =cs i ;

[0031] When the signature codeword sequence is distributed insertion, that is, when Ms data symbols are uniformly inserted into Ns signature codeword symbols, the modulation sequence cs i Insert Ms zero-value symbols every Ns signature code symbols to form a new modulation sequence cs2 i ,

[0032]

[0033] Preferably, step S26 further includes the following steps:

[0034] S26.1: setting a threshold value thr according to the signal characteristic codeword type, signal-to-noise ratio and characteristic codeword sequence length;

[0035] S26.2: Query the relevant modulo sequence r xy The index {ind1, ind2, ..., ind i ,...}, and count counts;

[0036] S26.3: When the difference between two consecutive indexes is equal, the following conditions are met:

[0037] if counts≥3&&Δind=ind i+3-ind i+2 =ind i+2 -ind i+1 ;

[0038] Then the received signal is identified as the current feature codeword sequence b i The corresponding VSAT network station type and end the identification;

[0039] When the current feature codeword sequence b i If the VSAT network station type is not identified, the encoding method is modified and steps S22 to S26 are repeated;

[0040] S26.4: If the VSAT network station type is still not identified in step S26.3, then i=i+1 and loop through b i , repeat steps S22 to S26 until the recognition is completed or all the feature code words are traversed.

[0041] The present invention has the following advantages:

[0042] 1. The present invention performs network station identification in the timing synchronization stage. At this time, the timing synchronization signal itself has a certain frequency offset and phase offset. Through the cross-correlation operation between the timing synchronization signal and the characteristic code word sequence, the characteristic code word sequence matching of different starting points is covered. Therefore, there is no need to consider the influence of the characteristic code word sequence on the matching identification due to different starting points. The identification process does not require carrier recovery (demodulation) of the signal, so there is no need to consider the phase ambiguity problem caused by signal demodulation. The identification task can be completed only after the timing synchronization is completed, thereby greatly simplifying the complexity of the identification algorithm and improving the recognition efficiency.

[0043] 2. When the present invention performs VSAT network station identification, the feature codeword matching and identification of the distributed insertion structure is performed based on the interpolation method, so that it is unified with the feature codeword matching and identification completion algorithm of the centralized insertion structure, which simplifies the matching and identification of the feature codewords of the distributed insertion structure and improves the operation efficiency.

[0044] 3. The present invention utilizes cross-correlation operation, and the correlation domain reduces the sensitivity to background noise changes during the recognition process, and has good robustness, that is, it can complete the recognition task even for low signal-to-noise ratio signals. However, under the condition of low signal-to-noise ratio signals, the prior art cannot complete demodulation lock in the demodulation stage or the demodulation bit error rate is too high, resulting in the inability to perform subsequent recognition tasks. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the VSAT network station identification method flow;

[0046] Figure 2 It is a schematic diagram of the network station recognition results of the centralized characteristic codeword under different signal-to-noise ratios;

[0047] Figure 3 It is a schematic diagram of the network station recognition results of distributed characteristic codewords under different signal-to-noise ratios;

[0048] Figure 4 A schematic diagram of the VSAT network station identification results based on demodulated data. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0050] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0052] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0053] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0054] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] In this embodiment, if Figure 1 to Figure 4 As shown, a satellite signal VSAT network station identification method comprises the following steps:

[0056] S1: Receive the target signal through the antenna and process the signal to obtain the timing synchronization signal r s ;

[0057] S2: with timing synchronization signal r s As input, the target signal is matched and identified for the VSAT network station type based on the characteristic codeword sequence and its insertion structure. Since the network station identification is performed in the timing synchronization stage, the timing synchronization signal itself has a certain frequency offset and phase offset. Through the cross-correlation operation between the timing synchronization signal and the characteristic codeword sequence, the characteristic codeword sequence matching of different starting points is covered. Therefore, there is no need to consider the influence of the characteristic codeword sequence on the matching identification due to different starting points. The identification process does not require carrier recovery (demodulation) of the signal, so there is no need to consider the phase ambiguity problem caused by signal demodulation. The identification task can be completed only after the timing synchronization is completed, thereby greatly simplifying the complexity of the identification algorithm and improving the identification efficiency. Further, in step S1, the target signal is first subjected to frequency conversion filtering, carrier frequency estimation and rate estimation to obtain a zero intermediate frequency signal, and then matched filtering and clock recovery to obtain a timing synchronization signal. Specifically, in step S1, the existing method is used to process the signal, which is not improved here and will not be repeated. Further, the mathematical model of the timing synchronization signal is:

[0058]

[0059] in, is the kth symbol in the received signal, A is the symbol waveform amplitude, Δω is the frequency deviation, T is the symbol duration, is the phase deviation, and n(k) is the Gaussian white noise with power spectral density n0.

[0060] In this embodiment, step S2 further includes the following steps:

[0061] S21: The feature code word sequences corresponding to different VSAT network station types are grouped into a sequence set to form a feature code word sequence matching library.

[0062] 1≤i≤n,1≤j≤m;

[0063] in, is the jth codeword in the characteristic codeword sequence corresponding to the i-th VSAT network station, n is the number of VSAT network station types, and m is the length of the characteristic codeword sequence corresponding to the VSAT network station;

[0064] S22: The feature codeword sequence b corresponding to the i-th VSAT network station i , according to the modulation style corresponding to the target signal, it is mapped into the modulation sequence cs i ; Further, step S22 further includes the following steps:

[0065] S22.1: Convert the binary sequence b i Group and map symbols according to the rules to get the symbol sequence s i ;

[0066] S22.2: The symbol sequence s after symbol mapping i , modulate according to the modulation style corresponding to the target signal, and obtain the symbol modulation sequence cs i . Taking the most commonly used QPSK as an example, specifically, there are two specific rules here. One is the Gray coding counter-clockwise coding method [0,1,3,2], where symbol 0 corresponds to the binary code word "00", corresponding to the first quadrant of the complex plane; symbol 1 corresponds to the binary code word "01", corresponding to the second quadrant of the complex plane; symbol 3 corresponds to the binary code word "11", corresponding to the third quadrant of the complex plane; symbol 2 corresponds to the binary code word "10", corresponding to the fourth quadrant of the complex plane; the second is the Gray coding clockwise coding method [0,2,3,1], where symbol 0 corresponds to the binary code word "00", corresponding to the first quadrant of the complex plane; symbol 2 corresponds to the binary code word "10", corresponding to the second quadrant of the complex plane; symbol 3 corresponds to the binary code word "11", corresponding to the third quadrant of the complex plane; symbol 1 corresponds to the binary code word "01", corresponding to the fourth quadrant of the complex plane. Step S22 converts the binary sequence b i Group by two, such as And perform encoding mapping according to one of the rules to obtain a symbol sequence,

[0067] k=1,2,...,K, in, It represents the kth symbol in the symbol sequence mapped to the characteristic codeword corresponding to the i-th VSAT network station, and the symbol number K is half of the binary bit number m;

[0068] Then calculate the symbol sequence s i Each element in The corresponding index in the encoding method [0,1,3,2] or [0,2,3,1] like The index position in the sequence [0,1,3,2] is 2; The index position in the [0,2,3,1] sequence is 4, and its calculation formula is:

[0069] k=1,2,...,K;

[0070] k=1,2,...,K;

[0071] in, The phase of the kth symbol in the symbol sequence mapped to the characteristic codeword corresponding to the i-th VSAT network station has four possible values: [π / 4, 3π / 4, 5π / 4, 7π / 4], which correspond to the first, second, third, and fourth quadrants of the complex plane, respectively. The symbol sequence s representing the mapping of the characteristic codeword corresponding to the i-th VSAT network station i The kth complex value of the modulation symbol.

[0072] S23: Modulation sequence cs i Interpolate according to the insertion structure of the characteristic codeword sequence to obtain a new characteristic codeword modulation sequence cs2 i ; Further, the interpolation processing specifically includes:

[0073] When the signature codeword sequence is inserted in a centralized manner, the modulation sequence cs i No processing, cs2 i =cs i ;

[0074] When the signature codeword sequence is distributed insertion, that is, when Ms data symbols are uniformly inserted into Ns signature codeword symbols, the modulation sequence cs i Insert Ms zero-value symbols every Ns signature code symbols to form a new modulation sequence cs2 i ,

[0075]

[0076] Specifically, when performing VSAT network station identification, the feature codeword matching and identification of the distributed insertion structure is performed based on the interpolation method, which unifies the algorithm with the feature codeword matching and identification completion algorithm of the centralized insertion structure, simplifies the matching and identification of the feature codewords of the distributed insertion structure, and improves the computing efficiency.

[0077] S24: cs2 i Multiply it with its delayed conjugate sequence to get the characteristic codeword modulation differential sequence d_cs2 i , Where M is the characteristic codeword modulation sequence cs2 i The length of , conj() is to take the conjugate;

[0078] The timing synchronization signal r s Multiply it with its delayed conjugate sequence to get the timing synchronization signal differential sequence d_r s ,

[0079]

[0080] Where N is the timing synchronization signal r s The length of , conj() means taking the conjugate;

[0081] S25: Modulate the differential sequence d_cs2 according to the characteristic code word i Differential sequence d_r with timing synchronization signal s Get the relevant modulo sequence,

[0082]

[0083] Where x is the timing synchronization signal differential sequence d_r s , y is the characteristic codeword modulation differential sequence d_cs2 i ;

[0084] S26: Identify the type of the VSAT network station. Preferably, step S26 further includes the following steps:

[0085] S26.1: setting a threshold value thr according to the signal characteristic codeword type, signal-to-noise ratio and characteristic codeword sequence length;

[0086] S26.2: Query the relevant modulo sequence r xy The index {ind1, ind2, ..., ind i ,...}, and count counts;

[0087] S26.3: When the difference between two consecutive indexes is equal, the following conditions are met:

[0088] if counts≥3&&Δind=ind i+3 -ind i+2 =ind i+2 -ind i+1 ;

[0089] Then the received signal is identified as the VSAT network station type corresponding to the current feature codeword sequence bi, and the identification is terminated;

[0090] When the current feature codeword sequence b i If the VSAT network station type is not identified, the encoding method is modified and steps S22 to S26 are repeated;

[0091] S26.4: If the VSAT network station type is still not identified in step S26.3, then i=i+1 and loop through b i , repeat steps S22 to S26 until the recognition is completed or all the characteristic codewords are traversed. Specifically, by using the cross-correlation operation, the correlation domain reduces the sensitivity to the background noise change during the recognition process, and has good robustness, that is, it can complete the recognition task even for low signal-to-noise ratio signals. However, under the condition of low signal-to-noise ratio signals, the existing technology cannot complete the demodulation lock in the demodulation stage or the demodulation bit error rate is too high, resulting in the inability to perform subsequent recognition tasks.

[0092] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A satellite signal VSAT network station identification method, characterized in that: The following steps are involved: S1: Receive the target signal through the antenna and process the signal to obtain the timing synchronization signal r s ; S2: with timing synchronization signal r s As input, the target signal is matched and identified with the VSAT network station type based on the characteristic codeword sequence and its insertion structure; The step S2 further includes the following steps: S21: The feature code word sequences corresponding to different VSAT network station types are grouped into a sequence set to form a feature code word sequence matching library. in, is the jth codeword in the characteristic codeword sequence corresponding to the i-th VSAT network station, n is the number of VSAT network station types, and m is the length of the characteristic codeword sequence corresponding to the VSAT network station; S22: The feature codeword sequence b corresponding to the i-th VSAT network station i , according to the modulation style corresponding to the target signal, it is mapped into the modulation sequence cs i ; S23: Modulation sequence cs i Interpolate according to the insertion structure of the characteristic codeword sequence to obtain a new characteristic codeword modulation sequence cs2 i ; S24: cs2 i Multiply it with its delayed conjugate sequence to get the characteristic codeword modulation differential sequence d_cs2 i , Where M is the characteristic codeword modulation sequence cs2 i The length of , conj() is to take the conjugate; The timing synchronization signal r s Multiply it with its delayed conjugate sequence to get the timing synchronization signal differential sequence d_r s , Where N is the timing synchronization signal r s The length of , conj() means taking the conjugate; S25: Modulate the differential sequence d_cs2 according to the characteristic code word i Differential sequence d_r with timing synchronization signal s Get the relevant modulo sequence, Where x is the timing synchronization signal differential sequence d_r s , y is the characteristic codeword modulation differential sequence d_cs2 i ; S26: Identify the type of VSAT network station.

2. The satellite signal VSAT network station identification method according to claim 1, characterized in that: In the step S1, the target signal is first subjected to frequency conversion filtering, carrier frequency estimation and rate estimation to obtain a zero intermediate frequency signal, and then subjected to matched filtering and clock recovery to obtain a timing synchronization signal.

3. The satellite signal VSAT network station identification method according to claim 2 is characterized in that: The mathematical model of the timing synchronization signal is: in, is the kth symbol in the received signal, A is the symbol waveform amplitude, Δω is the frequency deviation, T is the symbol duration, is the phase deviation, and n(k) is the Gaussian white noise with power spectral density n0.

4. The satellite signal VSAT network station identification method according to claim 3 is characterized in that: The step S22 further includes the following steps: S22.1: Convert the binary sequence b i Group and map symbols according to the rules to get the symbol sequence s i ; S22.2: The symbol sequence s after symbol mapping i , modulate according to the modulation style corresponding to the target signal, and obtain the symbol modulation sequence cs i .

5. The satellite signal VSAT network station identification method according to claim 4 is characterized in that: In step S23, the interpolation process specifically includes: When the signature codeword sequence is inserted in a centralized manner, the modulation sequence cs i No processing, cs2 i =cs i ; When the signature codeword sequence is distributed insertion, that is, when Ms data symbols are uniformly inserted into Ns signature codeword symbols, the modulation sequence cs i Insert Ms zero-value symbols every Ns signature code symbols to form a new modulation sequence cs2 i , 6. The satellite signal VSAT network station identification method according to claim 5, characterized in that: The step S26 further includes the following steps: S26.1: setting a threshold value thr according to the signal characteristic codeword type, signal-to-noise ratio and characteristic codeword sequence length; S26.2: Query the relevant modulo sequence r xy The indices {ind1, ind2, ..., ind i , ...}, and count counts; S26.3: When the difference between two consecutive indexes is equal, the following conditions are met: if counts≥3&&Δind=ind i+3 -ind i+2 =ind i+2 -ind i+1 ; Then the received signal is identified as the current feature codeword sequence b i The corresponding VSAT network station type and end the identification; When the current feature codeword sequence b i If the VSAT network station type is not identified, the encoding method is modified and steps S22 to S26 are repeated; S26.4: If the VSAT network station type is still not identified in step S26.3, then i=i+1 and loop through b i , repeat steps S22 to S26 until the recognition is completed or all the feature code words are traversed.

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