Method for distinguishing small station signal interference of satellite TDMA (Time Division Multiple Access) system

Abstract

The invention relates to a method for distinguishing small station signal interference of a satellite TDMA (Time Division Multiple Access) system, and belongs to the field of satellite communication. Satellite small station signals need to be received through the receiver, modulation signals received by the satellite communication signal receiving module are sent to the modulation identification module to be identified, demodulation is carried out according to the identification result of the modulation identification module, and according to data resolved by the demodulation module, the small station signals are received through the receiver. And the time slot analysis module counts the number of time slots in the burst, shears the modulation signal according to the counted number of time slots and the user feature code, sends the sheared modulation signal to a network training model for training, judges the identity of the user according to the training model, and judges that the user is interference if the user is not the trained user. Multi-user coarse classification and time domain division are realized according to time slots and user feature codes, once an external user forcibly enters, the identity of the user can be identified immediately, if the identity is matched with a radiation source user feature library, the user is regarded as a legal user, and otherwise, the user is regarded as external interference.

Description

Technical Field

[0001] The present invention belongs to the field of satellite communication, and particularly relates to a method for discriminating signal interference of small stations in a satellite TDMA system. Background Art

[0002] Satellite communication has the advantages of long communication distance, wide frequency band, large transmission capacity, stable communication line, few intermediate links, and multi-path transmission. However, satellite communication has always had security problems and is vulnerable to attacks and eavesdropping. In a satellite communication system, small stations are often the main targets of interference and attacks. Interference may come from external signal power suppression interference; it may also come from signal spoofing interference of the same communication system. External power interference can use spread spectrum or frequency hopping anti-interference technologies to improve the anti-interference ability of signals. However, the problem of spoofing interference has not been solved efficiently and accurately so far. Therefore, how to quickly and effectively determine the interference source of small stations is an important problem to be solved in the current satellite communication system.

[0003] Based on this, how to quickly and accurately identify the interference source of satellite small stations is the current research focus of satellite communication. The present invention proposes a method for discriminating signal interference of small stations in a satellite TDMA system. This method uses the time slots of small stations and user feature codes to achieve rough classification of multiple users and time domain division, and then uses radiation source individual recognition technology for user identification and verification. The interference source is compared with the fingerprint feature library of radiation sources, and then discrimination is carried out, and whether to give an early warning is determined according to the discrimination result. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] The technical problem to be solved by the present invention is how to provide a method for discriminating signal interference of small stations in a satellite TDMA system to solve the problem of quickly and accurately identifying the interference source of satellite small stations.

[0006] (2) Technical Solutions

[0007] To solve the above technical problems, the present invention proposes a method for discriminating signal interference of small stations in a satellite TDMA system, and the method includes the following steps:

[0008] The first step: The satellite communication signal receiving module receives the satellite communication signal through a receiver;

[0009] The second step: The modulation recognition module recognizes the modulation mode of the signal according to the instantaneous characteristic parameter algorithm;

[0010] The third step: The demodulation module demodulates the satellite communication signal;

[0011] The fourth step: The time slot analysis module divides users according to time slots and cuts the signals where the time slots are located;

[0012] Step 5: The user feature code module extracts the feature codes of the small station users from the signals, distinguishes the small station users according to the small station user feature codes, and cuts the data corresponding to the user according to the time slot and the user feature code.

[0013] Step 6: The radiation source user identification module classifies the original modulation signals according to the time slot analysis module and the user feature code module. The same small station users in different time slots are grouped together, so that the small station signals are divided into multiple users, and finally the training set and verification set of different users are formed; individual training of the radiation source is carried out according to the user classification to obtain a network training model; according to the network training model, the user identity is judged. If the user is not the trained user, it is determined as interference and the early warning is started.

[0014] (3) Beneficial effects

[0015] The present invention proposes a method for discriminating interference of small station signals in the satellite TDMA system. The main advantages of the present invention are as follows: multi-user rough classification and time domain division are realized according to the time slot and the user feature code, and a radiation source user feature library is established based on the small station user data. Each user has a unique feature. Once an external user forces entry, the user identity will be immediately identified. If it matches the radiation source user feature library, it is considered a legitimate user; otherwise, it is considered external interference. Description of the drawings

[0016] Figure 1 is a flow chart of the method for discriminating interference and early warning of small station signals in the satellite TDMA system according to the present invention;

[0017] Figure 2 is a schematic diagram of TDMA burst;

[0018] Figure 3 is a time slot diagram;

[0019] Figure 4 is a schematic diagram of the feature code of small station user 1;

[0020] Figure 5 is a schematic diagram of the feature code of small station user 2;

[0021] Figure 6 is a schematic diagram of the feature codes of small station user 1 and small station user 3. Specific embodiments

[0022] To make the objectives, contents and advantages of the present invention clearer, the specific embodiments of the present invention will be further described in detail below with reference to the drawings and embodiments.

[0023] To solve the above problems, the present invention proposes a method for discriminating interference of small station signals in the satellite TDMA system.

[0024] The present invention proposes a method for discriminating satellite TDMA system small station signal interference, which mainly includes: a satellite communication signal receiving module, a modulation recognition module, a demodulation module, a time slot analysis module, a user characteristic code module, and a radiation source user identification module.

[0025] First step, the satellite communication signal receiving module receives the satellite communication signal through a receiver.

[0026] Second step, the modulation recognition module identifies the modulation mode of the signal according to the instantaneous characteristic parameter algorithm.

[0027] Satellite communication signals contain rich instantaneous information, specifically including: instantaneous phase, instantaneous amplitude, instantaneous frequency, and statistical characteristic values obtained from different angles. Among these information, instantaneous amplitude, instantaneous phase, and instantaneous frequency are the key carriers of modulation information. In order to effectively identify the modulation mode of satellite communication signals, it is necessary to accurately extract the amplitude, phase, and frequency characteristics of the signals. Based on these instantaneous values, the instantaneous characteristic parameters of the modulation signal can be further derived. The present invention focuses on using three core instantaneous characteristic parameters, including: the maximum spectral density of instantaneous amplitude, the standard deviation of the absolute value of instantaneous phase, and the standard deviation of the absolute value of instantaneous frequency, to achieve more accurate modulation recognition of satellite communication signals. Common modulation modes of satellite signals include 2PSK, 4PSK, 2FSK, 4FSK, 2ASK, 4ASK, etc.

[0028] Third step, the demodulation module demodulates the satellite communication signal.

[0029] The demodulation of satellite communication signals is the inverse process of modulation, mainly converting the received modulated signal back to the original baseband signal. The methods involved in demodulation, such as frequency demodulation, phase demodulation, etc., are specifically selected depending on the modulation mode.

[0030] Fourth step, the time slot analysis module divides users according to time slots and cuts the signals where the time slots are located.

[0031] The communication mode of satellite small stations is TDMA communication. The main feature of TDMA communication mode is that each ground station only transmits modulated signals in a burst form within the specified time slots. These signals are strictly sorted in sequence and non-overlapping in time when being forwarded, and each ground station must transmit signals to the satellite using the same carrier. Signals entering the satellite transponder in different time slots are sorted in time order, being both compact and non-overlapping. After being amplified by the satellite transponder, they are retransmitted back to the ground along the downlink. Therefore, each time slot only contains the information of one user, and users can be divided according to time slots and the signals where the time slots are located can be cut.

[0032] Step 5: The user feature code module extracts the feature codes of the small station users from the signals. Since a small station signal has multiple bursts, each burst contains multiple time slots, and each time slot represents a user, and each user has a unique feature code, the small station users can be distinguished according to the small station user feature codes, and the data corresponding to the user can be clipped according to the time slots and user feature codes.

[0033] Step 6: The radiation source user identification module classifies the original modulation signals according to the time slot analysis module and the user feature code module. The different time slots of the same small station user are put together, and the small station signals can be divided into multiple users, and finally the training set and verification set of different users are formed. According to the user classification, individual training of the radiation source is carried out to obtain a network training model; according to the network training model, the user identity is judged. If the user is not the trained user, it is determined as interference and the early warning is started.

[0034] The radiation source user identification module mainly has the following steps:

[0035] S61: Classify the original modulation signals according to the time slot analysis module and the user feature code module;

[0036] S62: Divide the classified small station user data into a training set and a verification set. The training set data accounts for 70%, and the verification set data accounts for 30%;

[0037] S63: Send the training set data to the network training model in batches for training;

[0038] S64: Send the verification set data to the network training model at the same time for verification.

[0039] S65: Finally, the network training model extracts the features of each user according to the small station user data for small station user classification.

[0040] S66: According to the network training model, judge the user identity. If the user is not the trained user, it is determined as interference and the early warning is started

[0041] Embodiment 1:

[0042] In this embodiment, refer to Figure 1As shown in the figure, the present invention proposes a method for discriminating and warning against interference of small station signals in the satellite TDMA system. The first step is that the satellite small station signal needs to be received by the receiver first. The second step is to send the modulated signal received by the satellite communication signal receiving module into the modulation recognition module for recognition. The third step is to demodulate according to the result recognized by the modulation recognition module. The fourth step is that according to the data decoded by the demodulation module, the time slot analysis module counts the number of time slots in this burst. The fifth step is to clip the modulated signal according to the counted number of time slots and the user characteristic code. The sixth step is to send the clipped modulated signal into the network training model for training. According to the training model, the user identity is discriminated. If it is not the trained user, it is determined as interference and the warning is started. The specific steps are as follows:

[0043] The first step: The satellite communication signal receiving module mainly receives the satellite communication signal through the receiver;

[0044] The second step: The modulation recognition module mainly identifies the modulation mode of the signal according to the instantaneous characteristic parameter algorithm. The satellite communication signal contains rich instantaneous information, specifically including instantaneous phase, instantaneous amplitude, instantaneous frequency, and statistical characteristic values obtained from different angles. Among these information, instantaneous amplitude, instantaneous phase, and instantaneous frequency are the key carriers of modulation information. In order to effectively identify the modulation mode of the satellite communication signal, it is necessary to accurately extract the amplitude, phase, and frequency characteristics of the signal. Based on these instantaneous values, the instantaneous parameters of the modulated signal can be further deduced. The present invention focuses on using three core characteristic parameters: the maximum spectral density of the instantaneous amplitude, the standard deviation of the absolute value of the instantaneous phase, and the standard deviation of the absolute value of the instantaneous frequency to achieve more accurate modulation recognition of satellite communication signals. Common modulation modes of satellite signals include 2PSK, 4PSK, 2FSK, 4FSK, 2ASK, 4ASK, etc.

[0045] The third step: The demodulation module. The demodulation of the satellite communication signal is the inverse process of modulation, mainly to convert the received modulated signal back to the original baseband signal. The methods involved in demodulation, such as frequency demodulation, phase demodulation, etc., are specifically selected depending on the modulation mode.

[0046] The fourth step: The time slot analysis module. The communication mode of the satellite small station is TDMA communication. The main feature of the TDMA communication mode is that each ground station only transmits the modulated signal in the form of a burst within the specified time slot. These signals are strictly sorted in sequence and do not overlap in time when being forwarded, and each ground station must transmit signals to the satellite using the same carrier. The signals entering the satellite transponder in different time slots are sorted in time sequence, which is both compact and non-overlapping. After being amplified by the satellite transponder, they are retransmitted back to the ground along the downlink. Therefore, each time slot only contains the information of one user, and the users can be divided according to the time slot, and the modulated signal where the time slot is located is clipped.

[0047] As Figure 2 shown in the TDMA burst diagram, it can be seen that the signal of the small station is sent in a burst form, which conforms to the TDMA communication method and is sent at regular intervals according to time.

[0048] As Figure 3 shown in the time slot diagram, it can be seen that a burst contains multiple time slots. One time slot represents one user, which may be the same user or different users. There is an obvious interval between time slots, so users can be clipped according to time slots.

[0049] Step 5: User feature code module. This module mainly extracts the feature codes of small station users. Since a small station signal has multiple bursts, and a burst contains multiple time slots, and one time slot represents one user, and one user has a unique feature code, small station users can be distinguished according to the feature codes of small station users.

[0050] As Figure 4 shown in the feature code of small station user, small station user 1 occupies multiple time slots in this burst, and according to Figure 5 shown in the feature code of small station user 2, it shows that small station user 2 occupies multiple time slots in the burst.

[0051] As Figure 6 shown in the feature codes of small station user 1 and small station user 3, the same burst contains two feature codes of small station users. It is impossible to complete the division according to the time slot module, and only the feature codes of small station users can be used for distinction.

[0052] Therefore, according to the time slot analysis module, it can be analyzed how many time slots there are in the burst, and the time slots and the feature codes of small station users are combined. One time slot contains one feature code of a small station user. If the feature code of the small user changes, it means that the small station user has changed, otherwise the small station user has not changed. In short, the data corresponding to the user can be clipped according to the time slot and the user feature code.

[0053] Step 6: The radiation source user identification module mainly classifies the original modulation signal according to the time slot analysis module and the user feature code module. The different time slots of the same small station user are put together, and the small station signal can be divided into multiple users, and finally the training set and verification set of different users are formed. Individual training of the radiation source is carried out according to the user classification.

[0054] The radiation source user identification module mainly has the following steps:

[0055] S61: Classify the original modulation signal according to the time slot analysis module and the user feature code module;

[0056] S62. Divide the classified small-station user data into a training set and a validation set, with the training set data accounting for 70% and the validation set data accounting for 30%.

[0057] S63. Send the training set data into the network training model in batches for training.

[0058] S64. Send the validation set data into the network training model for validation at the same time.

[0059] S65. Finally, the network training model extracts the features of each user based on the small-station user data for small-station user classification, discriminates the user identity. If the user is not a trained user, it is determined as interference and an early warning is initiated.

[0060] As can be seen from the above steps, the present invention proposes a method for discriminating and warning against small-station signal interference in the satellite TDMA system. First, the satellite small-station signal needs to be received by the receiver. Second, the modulated signal received by the satellite communication signal receiving module is sent to the modulation recognition module for recognition. Third, demodulation is performed according to the result recognized by the modulation recognition module. Fourth, according to the data demodulated by the demodulation module, the time slot analysis module counts the number of time slots in the burst. Fifth, the modulated signal is clipped according to the counted number of time slots and the user feature code. Sixth, the clipped modulated signal is sent to the network training model for training. According to the training model, the user identity is discriminated. If the user is not a trained user, it is determined as interference.

[0061] The main advantages of the present invention are as follows: multi-user rough classification and time-domain division are realized according to time slots and user feature codes, and a radiation source user feature library is established based on small-station user data. Each user has a unique feature. Once an external user tries to enter forcibly, the user identity will be immediately recognized. If it matches the radiation source user feature library, it is considered a legal user; otherwise, it is considered external interference.

[0062] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for determining interference of satellite TDMA small-station signals, characterized in that: The method comprises the following steps: The first step is that the satellite communication signal receiving module receives the satellite communication signal through the receiver; In the second step, the modulation identification module identifies the modulation mode of the signal according to the instantaneous characteristic parameter algorithm; The third step is that the demodulation module demodulates the satellite communication signal; Step 4: The time slot analysis module divides the users according to the time slots and cuts the signals in the time slots; Step 5: The user feature code module extracts the feature code of the small station user from the signal, distinguishes the small station user according to the small station user feature code, and cuts the data corresponding to the user according to the time slot and the user feature code; Step 6: The radiation source user identification module classifies the original modulated signal according to the time slot analysis module and the user feature code module, and puts the same small station users in different time slots together, thereby dividing the small station signal into multiple users, and finally forming training sets and verification sets for different users; the radiation source individual training is performed according to the user classification to obtain the network training model; According to the network training model, the user's identity is determined. If it is not a trained user, it is considered as interference and an early warning is initiated.

2. The method for determining interference of satellite TDMA small station signals as claimed in claim 1, characterized in that: In the second step, the instantaneous information contained in the satellite communication signal includes: instantaneous phase, instantaneous amplitude, instantaneous frequency and statistical characteristic values ​​obtained from different angles. Among these information, instantaneous amplitude, instantaneous phase and instantaneous frequency are the key carriers of modulation information. Based on these instantaneous values, the instantaneous characteristic parameters of the modulated signal are further derived.

3. The method for determining interference of satellite TDMA small station signals as claimed in claim 2, characterized in that: In the second step, the instantaneous characteristic parameters include: the maximum value of the spectral density of the instantaneous amplitude, the standard deviation of the absolute value of the instantaneous phase, and the standard deviation of the absolute value of the instantaneous frequency.

4. The method for determining interference of satellite TDMA small station signals as claimed in claim 2, characterized in that: In the second step, the modulation modes include: 2PSK, 4PSK, 2FSK, 4FSK, 2ASK and 4ASK.

5. The method for determining interference of satellite TDMA small station signals as claimed in claim 1, characterized in that: In the third step, the received modulated signal is converted back to the original baseband signal, and the demodulation method includes: frequency demodulation and phase demodulation.

6. The method for determining interference of satellite TDMA small station signals as claimed in claim 1, characterized in that: In the fourth step, the satellite station communication mode is TDMA communication, each ground station transmits modulated signals in the form of bursts only in the specified time slot, these signals are strictly sequenced in time when forwarded, do not overlap each other, and each ground station must use the same carrier to transmit signals to the satellite; signals entering the satellite transponder at different time slots are sequenced in time order; After being amplified by the satellite transponder, it is sent back to the ground along the downlink; therefore, each time slot only contains the information of one user, the users are divided according to the time slots, and the signals in the time slots are cut.

7. The method for determining interference of satellite TDMA small station signals as claimed in claim 6, characterized in that: In the fourth step, one time slot represents one user, which may be the same user or different users. There is a clear interval between time slots, and users are cut according to the time slots.

8. The method for determining interference of satellite TDMA small station signals as claimed in claim 6, characterized in that: In the fifth step, a small station signal has multiple bursts, a burst contains multiple time slots, and a time slot represents a user. A user has a unique feature code. The small station users are distinguished according to the small station user feature code, and the data corresponding to the user is cut according to the time slot and user feature code.

9. The method for determining interference of satellite TDMA small station signals as claimed in claim 8, characterized in that: In the fifth step, the time slot analysis module is used to analyze the specific number of time slots in the burst, and the time slot and the small station user characteristic code are combined. One time slot contains a small station user characteristic code. If the small user characteristic code changes, it means that the small station user has changed, otherwise the small station user has not changed; the data corresponding to the user is cut according to the time slot and user characteristic code.

10. The method for determining interference of satellite TDMA small station signals as claimed in claim 9, characterized in that: The sixth step specifically includes: S61, classifying users of the original modulated signal according to the time slot analysis module and the user feature code module; S62, dividing the classified small station user data into a training set and a validation set, where the training set data accounts for 70% and the validation set data accounts for 30%; S63, sending the training set data to the network training model in batches for training; S64, sending the verification set data to the network training model for verification; S65. Finally, the network training model extracts the characteristics of each user according to the small station user data to classify the small station users and identify the user. If the user is not a trained user, it is judged as interference and an early warning is initiated.

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