Multimode satellite mobile communication uplink signal real-time detection and identification method and system

Abstract

The present disclosure provides a multi-mode satellite mobile communication uplink signal real-time detection and identification method and system. Applied to the field of satellite mobile communication technology, the method comprises: performing wideband sampling on the obtained received signal to obtain sampling data, performing signal carrier detection on the sampling data, judging whether the sampling data contains a target signal, and if so, proceeding to the next step; performing channelization processing on the sampling data to obtain narrowband signals in different satellite system corresponding narrowband channels; performing TDMA signal detection on the narrowband signals to obtain signal specifications, wherein the TDMA signal detection comprises energy detection, correlation detection, and signal identification. The present disclosure has the advantages of: significantly improving the accurate identification capability of various satellite mobile communication terminal uplink signals, with a detection and identification accuracy of 99%; and the hardware cost of the present disclosure increases little, and has a low-cost application prospect.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of satellite mobile communication technology, in particular to a multi-standard satellite mobile communication uplink signal real-time detection and identification method and system. BACKGROUND

[0002] At present, the mainstream technical methods and products for radio security monitoring of satellite mobile communication user terminals are roughly divided into two categories. One is third-party professional monitoring equipment, which is designed for corresponding satellite systems (such as the fourth generation of maritime affairs, Dula and Iridium, etc.). The main features of its technical scheme are satellite uplink and downlink signal reception and safety monitoring under the guidance of network control signaling. The other is a general electromagnetic spectrum monitoring technical scheme, which uses spectrum analysis method to carry out spectrum monitoring on L frequency band, discovers and identifies the target spectrum characteristics, and thus confirms the communication behavior of the user terminal. The above two solutions are very common in practical application, but there are still some defects or deficiencies in their actual deployment and application.

[0003] (1) Signal monitoring technical scheme based on network control signaling guidance

[0004] This scheme is based on the principle of building chain / communication process of corresponding satellite user terminal to receive and process signals. For example, the building chain / communication process of BGAN communication system user terminal is as follows:

[0005] a. After the user turns on the mobile terminal, it receives the initial broadcast information of the global beam, including UTC time, regional beam carrier frequency, etc.

[0006] b. Then the mobile terminal enters the reception of regional beam signals, obtains the uplink registration carrier frequency, and completes the registration, location report and security mode authentication, and enters the standby state.

[0007] c. When the user calls or is called, the user-specific signaling assigns the communication frequency of the narrow point beam, and the uplink communication frequency is assigned through the user-specific signaling of the narrow point beam. In the same carrier frequency, the user data is distinguished by temporary ID number, thereby completing the user communication.

[0008] d. After the communication is over, return to the regional beam and re-enter the standby state.

[0009] According to the communication characteristics of this system, the design principle of the third-party professional monitoring equipment is as follows:

[0010] 1) Receive global announcement signals, obtain satellite announcement information through demodulation and decryption and information analysis, including point beam area division, current point beam area network control signaling frequency allocation, etc.

[0011] 2) According to the satellite announcement information, receive and process the current regional network control signaling and analyze it.

[0012] 3) According to the current regional network control signaling instructions to user terminal point beam uplink and downlink signal processing and analysis;

[0013] 4) When monitoring the user uplink signal in the area, the user can be monitored, and the identity information, location information and corresponding communication information are obtained.

[0014] The advantage of this scheme is that the satellite mobile communication monitoring is complete, and the current satellite beam (generally in the range of 600-800 kilometers) can obtain all user communication status and network control allocation information, and according to the network control signaling guide, the target user terminal communication monitoring in the focus area (uplink signal monitoring range is generally in the range of 10-30 kilometers, and the monitoring range is related to the deployment) can be realized.

[0015] But the biggest problem in practical application is high cost and high deployment requirement, the first aspect is the high cost of professional equipment, compared with the conventional electromagnetic spectrum monitoring, the satellite downlink signal needs to be received and processed, and professional satellite antenna is needed, and the signal receiving and processing scale is larger, so the cost is greatly increased (the cost of such professional equipment is 5-10 times that of conventional radio monitoring equipment); The second aspect is that the satellite communication system can be monitored single, if you want to realize each kind of satellite mobile communication monitoring, you need more equipment (need to increase 3-4 times); In addition, if you want to monitor in a large range, you need to consider the multi-device networking monitoring scheme, and the large-scale networking deployment cost will be difficult to bear, because you need to receive satellite downlink signal, there is a professional operation of antenna pointing to the star; In urban environment, you also need to consider signal shielding or electromagnetic interference and other factors, and the professional requirement is higher.

[0016] (2) Conventional electromagnetic spectrum monitoring solution

[0017] Analysis of various mainstream satellite mobile communication user link, its use frequency band is L band, only need to carry out L band signal radio monitoring, can use spectrum analysis technology to find each kind of satellite mobile communication terminal signal in the area of concern.

[0018] The advantage of this scheme is that the cost is relatively low, but the monitoring effect is defective: first, the signal recognition ability is poor, only relying on spectrum analysis can only find out whether there is signal; Using signal spectrum characteristics can only achieve partial recognition, and in urban environment, there are a lot of interference signals, which can easily lead to high false alarm rate of identification, and the identification accuracy is usually below 80-90%; Second, the signal cognition depth is not enough, only using frequency spectrum characteristics and parameter estimation can identify the modulation mode and modulation rate of the signal, but it is not enough to support the analysis of user current communication state, target location and other deep cognitive information.

[0019] The two solutions have advantages and disadvantages, but a good solution should be based on the spectrum monitoring technology solution, increase the one-way processing capability of various satellite terminal uplink signals, and improve the signal recognition and cognitive processing capability on the basis of maintaining low cost, which has strong practical deployment application benefits. SUMMARY

[0020] The present disclosure provides a multi-standard satellite mobile communication uplink signal real-time detection and recognition method and system, which solves the problem of supporting analysis of user current communication state, target position and other deep cognitive information on the basis of ensuring cost.

[0021] According to a first aspect of the present disclosure, a multi-standard satellite mobile communication uplink signal real-time detection and recognition method is provided. The method comprises:

[0022] The received signal is sampled to obtain sampling data, and the sampling data is subjected to carrier detection to determine whether the sampling data contains valid signals. If yes, the next step is entered.

[0023] The sampling data is subjected to channelization processing to obtain narrowband signals in different satellite system corresponding narrowband channels.

[0024] The narrowband signals are subjected to TDMA signal detection to obtain signal specifications, and the TDMA signal detection includes energy detection and correlation detection.

[0025] Further, the carrier detection specifically includes the following steps:

[0026] The sampling data is resampled and subjected to spectrum analysis to obtain analysis results.

[0027] The analysis results are subjected to carrier detection and signal parameter measurement to obtain signal parameters, including signal frequency, bandwidth characteristic parameter, signal level, signal signal-to-noise ratio and time characteristic.

[0028] Further, the spectrum analysis includes coarse analysis; the coarse analysis includes the following steps:

[0029] The 256-point resampled sampling data is taken as first processing data;

[0030] The first processing data is subjected to 256-point complex FFT analysis processing after being added with a Hamming window to obtain a first amplitude spectrum; the last 128 points of the first processing data are reserved, and the last 128 points of the first processing data in the resampled sampling data are taken as second processing data.

[0031] If the number of times of 256-point complex FFT analysis and processing is not equal to 15, the second to-be-processed data is taken as the first to-be-processed data, and the previous step is entered; if the number of times of 256-point complex FFT analysis and processing is equal to 15, the first amplitude spectrum is summed to obtain a 256-point total amplitude spectrum, and the next step is entered;

[0032] The total amplitude spectrum is divided by 256*15 to obtain an average amplitude spectrum, and 10*log (average amplitude spectrum) is calculated to obtain a logarithmic amplitude.

[0033] Further, the spectrum analysis includes fine analysis; the fine analysis specifically includes the following steps:

[0034] Based on the start of each time slot, 8192*14 sampling points of the resampled sampling data are intercepted, divided into 14 segments, each segment being 8192 complex sampling points, each segment of wide sampling data is added with a Hamming window and subjected to 8192-point complex FFT analysis and processing to obtain an amplitude spectrum;

[0035] The 14 amplitude spectra are summed to obtain a sum vector;

[0036] The sum vector is divided by 8192*14 to obtain an average sum vector, and 10*log (average sum vector) is calculated to obtain a logarithmic sum vector.

[0037] Further, the time characteristics include an end time of the signal and a start time of the signal, and the calculation of the end time and the start time includes the following steps:

[0038] Based on the analysis result, a narrow frequency signal is screened out , n=0,1,...,N-1, the sliding energy of the narrow frequency signal is expressed by the following formula:

[0039] , m=0,1,...,N-1-M,

[0040] wherein N and M are positive integers; a wavelet transform under multiple scales is performed on to obtain , , which represents a wavelet transform under a scale , j=1,2,...,J, J being a positive integer;

[0041] A multi-scale wavelet product is calculated according to the sliding energy:

[0042]

[0043] wherein ; let , if L is an odd number, and​ the local minimum point of L is , the local maximum point of L is , the start time of the signal is , and the end time of the signal is ; if L is even, and the two local maximum points with the largest amplitudes are and ( ), the start time of the signal is , and the end time of the signal is .

[0044] Further, the process of energy detection comprises:

[0045] passing the narrowband signal through a preset window, the preset window comprising a high threshold and a low threshold;

[0046] judging whether the start time of the narrowband signal is higher than the high threshold and lower than the low threshold, if yes, filtering out the narrowband signal and determining that there is no TDMA signal; if no, determining that the narrowband signal has a TDMA signal, and performing relevant detection on the TDMA signal.

[0047] Further, the process of relevant detection comprises:

[0048] performing relevant detection on the TDMA signal to obtain the signal specification corresponding to the TDMA signal through the constructed prior knowledge base;

[0049] the prior knowledge base comprises the preamble unique code sequence, signal modulation type, modulation rate, frame period, and time slot allocation specification of various satellite mobile communication signal specifications.

[0050] According to a second aspect of the present disclosure, a multi-standard satellite mobile communication uplink signal real-time detection and recognition system is provided, comprising the following modules:

[0051] a signal judgment module, configured to perform wideband sampling on the acquired received signal to obtain sampling data, perform carrier detection on the sampling data, and judge whether the sampling data contains an effective signal, if yes, proceed to the next step;

[0052] a channelization module, connected with the signal judgment module, configured to perform channelization processing on the sampling data to obtain narrowband signals in narrowband channels corresponding to different satellite systems;

[0053] a detection module, connected with the channelization module, configured to perform TDMA signal detection on the narrowband signals to obtain signal specifications, the TDMA signal detection comprising energy detection and relevant detection.​​

[0054] The beneficial effects of the present disclosure are:

[0055] (1) The present disclosure comprehensively utilizes spectrum grading smoothing, threshold self-adaptation and robust detection, etc. to realize carrier detection and signal parameter measurement of signals of multiple modulation modes (DPSK, pi / 4QPSK, OQPSK, GMSK, 16QAM, 16APSK, etc.), multiple symbol rates (8.4KBD~240KBD), and multiple burst frame lengths (5ms, 20ms, 80ms, 90ms, etc.); through a large amount of in-depth signal analysis, a priori knowledge base of satellite mobile communication uplink signal specifications is constructed, and through correlation detection and energy detection, accurate recognition processing effect of the signal is achieved; the present disclosure outputs the signal data after detection and recognition in real time, and can meet the use of subsequent signal processing;

[0056] (2) The present disclosure significantly improves the accurate recognition ability of various satellite mobile communication terminal uplink signals, and the detection and recognition accuracy rate reaches 99%;

[0057] (3) Compared with the conventional electromagnetic spectrum monitoring scheme, the hardware platform of the present disclosure is basically consistent, but the automatic processing ability of various satellite mobile communication terminal uplink signals and the depth cognitive ability of signal specifications are greatly improved; and in the convenience of deployment, installation and operation, etc., the present disclosure is more excellent than various professional monitoring schemes; the hardware cost increases little, and has a low-cost application prospect.

[0058] It should be understood that the content described in the summary section is not intended to limit the key or important features of the embodiments of the present disclosure, nor to limit the scope of the present disclosure. Other features of the present disclosure will become apparent through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0059] The above and other features, advantages, and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. The drawings are intended to better understand the present disclosure, and do not constitute a limitation on the present disclosure. In the drawings, the same or similar reference numerals refer to the same or similar elements, wherein:

[0060] Figure 1 A flow chart of a multi-mode satellite mobile communication uplink signal real-time detection and recognition method provided by an embodiment of the present disclosure is shown;

[0061] Figure 2 A channelization processing schematic diagram provided by an embodiment of the present disclosure is shown;

[0062] Figure 3 A hardware platform schematic diagram provided by an embodiment of the present disclosure is shown;

[0063] Figure 4A framework diagram of a multi-mode satellite mobile communication uplink signal real-time detection and identification system provided by an embodiment of the present disclosure is shown.

[0064] Figure 5 A block diagram of an electronic device provided by an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are some but not all of the embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present disclosure.

[0066] In addition, the term “and / or” herein merely describes an association relationship of associated objects, and indicates that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. In addition, the character “ / ” herein generally represents an “or” relationship between the front and rear associated objects.

[0067] First, the following is explained:

[0068] Signal parameters describe the characteristics of signals themselves, and directly determine the information carrying capacity, transmission quality, and anti-interference performance of signals, such as frequency, phase, bandwidth, etc.

[0069] A communication system is a system rule framework for organizing signal transmission and realizing information interaction, and is defined for the purpose of realizing reliable information transmission, covering signal transmission methods, multiplexing / multiple access technologies, synchronization mechanisms, etc., and determines the capacity and applicable scenarios of a communication system. The essence is how to organize signal parameters to achieve the purpose of communication.

[0070] Signal specifications are standardized based on a communication system, and signal parameters are standardized to convert them into executable and verifiable parameter standards. A communication system contains many signal types, and each signal type is provided with a specific specification, i.e., a signal specification, such as a signal modulation type, a modulation rate, a frame format, a frame period, a time slot allocation specification, a unique preamble code sequence, and carried service information, etc. Different signal specifications are identified through signal detection, and the combination of different signal specifications represents different communication systems.

[0071] Exemplarily, a voice message is sent to a friend by a mobile phone. First, the voice message is converted according to the specification configuration of the signal parameters, such as converting the voice into a digital signal, and the signal frequency is adjusted to 1750 MHz. If the converted digital signal is to be sent out through a 4G communication system, the signal needs to be transmitted according to the rules agreed in advance, such as using orthogonal frequency division multiplexing, using AMR voice coding, etc. To transmit the signal through the 4G communication system, the unified signal specification standards also need to be followed, such as the uplink frequency being between 1710-1785 MHz, the OFDM subcarrier spacing being fixed at 15 kHz, etc. Through the above settings, the voice message is successfully transmitted.

[0072] It should be noted that in a communication process, the entire process from service initiation to completion is realized by the cooperation of multiple types of signals, and different signals bear different functions, such as establishing a connection, applying for resources, and transmitting service data. All types of signals are detected to determine the terminal type and communication content of the communication.

[0073] The present disclosure provides a multi-standard satellite mobile communication uplink signal real-time detection and identification method, as shown in Figure 1 , comprising the following steps:

[0074] S1, the received signal is sampled to obtain sampling data, and the sampling data is subjected to carrier detection to determine whether the sampling data contains valid signals. If yes, the next step is entered.

[0075] On a satellite mobile communication terminal, multiple signals may be received, which may be downlink signals from other satellites. Therefore, the first step is to identify whether the received signal contains an uplink signal, i.e., a valid signal, and then perform subsequent processing.

[0076] The process of wideband sampling includes: comprehensively analyzing the uplink signal frequency bands of various satellite mobile communication terminals, focusing on the 1616-1675 MHz part with a bandwidth of 60 MHz. The received signal is first passed through a band-pass filter, which only allows signals in the aforementioned frequency band to pass through, and then is subjected to AD sampling. The AD sampling adopts a zero intermediate frequency scheme, directly converts the filtered signal into a baseband signal, avoids intermediate frequency signal processing and relieves, simplifies the hardware structure, reduces signal distortion, and finally outputs two orthogonal signals of I and Q channels, i.e., sampling data, through zero intermediate frequency processing.

[0077] The sampling data is filtered to remove clutter interference, providing pure raw data source for subsequent calculation and avoiding the influence of clutter on subsequent analysis process.

[0078] Through carrier detection, the physical characteristics and transmission characteristics of the signal can be obtained. The specific process of carrier detection in the present disclosure includes:

[0079] S11, resample the sampling data and perform spectrum analysis to obtain an analysis result;

[0080] The sampling data is resampled to reasonably select a sampling rate to meet the FFT analysis processing requirement, and the disclosure utilizes sliding FFT analysis processing to implement spectrum analysis processing.

[0081] In the disclosure, the sliding FFT analysis processing process includes coarse analysis and fine analysis, wherein the coarse analysis specifically includes the following steps:

[0082] S1111, take the 256-point resampled sampling data as first to-be-processed data (0-255);

[0083] S1112, perform 256-point complex FFT analysis processing on the first to-be-processed data after adding a Hamming window to obtain a first amplitude spectrum;

[0084] Reserve the last 128 points of the first to-be-processed data, and take the last 128 points of the resampled sampling data as second to-be-processed data, perform 256-point complex FFT analysis processing on the second to-be-processed data after adding a Hamming window;

[0085] S1113, determine whether the number of times of performing 256-point complex FFT analysis processing is equal to 15, if not, take the second to-be-processed data as the first to-be-processed data, and enter the previous step; if yes, sum the first amplitude spectrum to obtain a total amplitude spectrum of 256 points, and enter the next step;

[0086] S1114, divide the total amplitude spectrum by 256*15 to obtain an average amplitude spectrum, and calculate 10*log(average amplitude spectrum) to obtain a logarithmic amplitude.

[0087] The fine analysis specifically includes the following steps:

[0088] S1121, based on the start of each time slot, intercept 8192*14 sampling points of the resampled sampling data, divide them into 14 segments, each segment being 8192 complex sampling points, add a Hamming window to each segment of wide data and perform 8192-point complex FFT analysis processing to obtain an amplitude spectrum;

[0089] S1122, sum the 14 amplitude spectrums to obtain a sum vector;

[0090] S1123, divide the sum vector (8192 points) by 8192*14 to obtain an average sum vector, and calculate 10*log(average sum vector) to obtain a logarithmic sum vector.

[0091] The spectrum analysis of the present disclosure firstly performs a coarse analysis of 256 points, and then performs accurate analysis of 8192 points to obtain a frequency domain analysis result. The combination of the coarse analysis and the fine analysis can quickly find out signal coupling, and the latter helps to accurately calculate signal parameters, so that through spectrum grading smoothing and step-by-step screening technology, efficient time-frequency domain analysis and processing of signals are realized.

[0092] S12, carrier detection and signal parameter measurement are performed on the analysis result to obtain signal parameters, the signal parameters including signal frequency, bandwidth characteristic parameter, signal level, signal signal-to-noise ratio and time characteristic.

[0093] On the basis of sliding FFT analysis and processing, the signal parameter calculation can be effectively realized by using robust detection and iterative correction technology, and the calculation results of signal carrier frequency, signal bandwidth, modulation type, symbol rate, signal-to-noise ratio and the like can be obtained.

[0094] Exemplarily, based on the analysis result, each signal frequency and bandwidth characteristic parameter can be estimated. At the same time, the signal level can be estimated by accumulating the energy in the signal bandwidth, and the signal signal-to-noise ratio can be calculated by further comparing and calculating the noise power accumulated in the non-signal frequency band. For the extraction of time characteristics, the distributed filtering technology is used to extract the frequency interval containing the effective signal from the analysis result to obtain a narrow frequency signal, and then the sliding energy of the narrow frequency signal is calculated, and the time characteristics are obtained by using multi-scale wavelet product for judgment.

[0095] Specifically, for the narrow frequency signal , n = 0, 1,..., N-1, the sliding energy is represented by the following formula:

[0096] , m = 0, 1,..., N-1-M,

[0097] wherein N and M are positive integers. The Haar wavelet basis is used to perform wavelet transform of under multiple scales to obtain , represents wavelet transform under the scale , j = 1, 2,..., J, and J is a positive integer. The multi-scale wavelet product is calculated according to the sliding energy:

[0098]

[0099] wherein . Let , if L is an odd number, the local minimum point of , The local maximum points of the signal are The start time of the signal is The end time of the signal is If L is even, The two local maximum points of the signal are and The start time of the signal is The end time of the signal is The start time and the end time obtained by calculation can be used to calculate the burst frame time slot length and the time of going out of the satellite.

[0100] According to the signal parameters obtained above and the existing communication signal categories, it can be preliminarily judged whether there is an effective signal, such as whether it is a maritime satellite signal.

[0101] In summary, the carrier detection is used to quickly find the signal, and provides a data premise for subsequent professional signal recognition.

[0102] S2, the sampling data is subjected to channelization processing to obtain narrowband signals in narrowband channels corresponding to different satellite systems.

[0103] The channelization parameters of different communication systems are different, so multiple channelizations need to be set for parallel processing.

[0104] Referring to Figure 2 Based on the prior knowledge of the uplink signals of various satellite mobile communication terminals, the wideband sampling data of the signals is buffered and subjected to uniform channelization processing, i.e. DDC extraction. According to the frequency allocation characteristics of different communication systems in the uplink signal frequency band, a plurality of narrowband channels are divided, and the sampling data is correspondingly divided according to the division of the narrowband channels, so as to obtain narrowband signals corresponding to the narrowband channels.

[0105] Taking the uplink signal of the BGAN system as an example, the nominal bandwidth of the transponder designed on the Inmarsat-4 satellite is 200 kHz (i.e. sub-bandwidth). If the entire L frequency band of the BGAN system is fully utilized, 170 sub-band channels can be allocated in the total bandwidth of 34 MHz. In the above case, the center frequency interval of each sub-band channel is stepped by 200 kHz, and the frequency offset compensation (i.e. the difference between the center frequency and the lowest frequency of the sub-bandwidth channel) of the center frequency of the sub-band channel is 100 kHz.

[0106] S3, the narrowband signals are subjected to TDMA signal detection to obtain signal specifications, and the TDMA signal detection includes energy detection and correlation detection.

[0107] ​​Through carrier detection in S1, the communication system is preliminarily determined, and it is confirmed that the signal is sent by a sea satellite, and the specific communication system is identified through channelization, and it is further confirmed that the signal is sent by which user, and the disclosure identifies various signal specifications in a specific communication system through TDMA signal detection.

[0108] Various satellite mobile communication terminal uplink signals often use time division multiple access (TDMA) to access. The sampled data of the uplink signal (1616-1675MHz) is uniformly channelized according to the uplink signal frequency allocation rules of BGAN, GSPS, Iridium, Dauraya, etc. to obtain different narrowband signals, and the narrowband signals are all in TDMA mode, that is, energy detection and correlation detection are performed on various TDMA signals to identify the signal type and specification.

[0109] Energy detection is used to identify whether there is a signal and to extract a burst frame (different burst frames may be for different users); different burst frames have various signal specifications, which can be distinguished through signal preamble unique code sequences; correlation detection is mainly performed through correlation detection of the signal preamble unique code sequence and the known sequence in the signal knowledge base, so as to identify the signal specification and type.

[0110] The performance of conventional burst detection, such as energy detection, is greatly affected by signal-to-noise ratio and signal accumulation length. When the burst duration is short, the gap between bursts is short, or the burst energy is low, the detection result will be greatly affected, and the detection effect of energy detection alone is not good. Since different types and specifications of signals of various satellite mobile communication terminals have different preamble unique code sequences, correlation detection is performed on the preamble unique code sequence of the TDMA signal, which not only has good detection performance but also synchronizes the frame to the code element. Therefore, the disclosure adopts a method combining energy detection and correlation detection, specifically, see the following description:

[0111] (1) Energy detection can use the time slot characteristics or frame period characteristics of various TDMA signals to predict the starting time of the next signal, and use a lower detection threshold within the predicted window range to improve the detection performance through a double-threshold detection method; the starting time of the signal missed by the high threshold can be obtained by low threshold detection, and the false alarm through the low threshold will also be filtered out by the frame period rule. Through energy detection, the narrowband signal passes through a preset window, and the preset window includes a high threshold and a low threshold; it is judged whether the starting time of the narrowband signal is higher than the high threshold and lower than the low threshold, if yes, the narrowband signal is filtered out, and it is determined that there is no TDMA signal; if not, it is determined that the narrowband signal has a TDMA signal, and the TDMA signal is subjected to correlation detection.

[0112] (2) The correlation detection needs to compare the signal specification of the TDMA signal with the known signal specification under the condition that the signal specification of the TDMA signal is known. Specifically, on the basis of analyzing the signal specifications of various satellite mobile communication terminal uplink signals, the prior knowledge of various signal specifications is obtained, such as the preamble unique code sequence, the signal modulation type, the modulation rate, the frame period, the time slot allocation specification, and the like, an prior knowledge base of various satellite mobile communication signal specifications is constructed, and the TDMA signal is subjected to correlation detection to obtain the signal specification corresponding to the TDMA signal by traversing the prior knowledge base.

[0113] In summary, by using the spectrum analysis technology, the signal measurement parameters such as the carrier frequency, the modulation type and the modulation bandwidth of various types are obtained; by using the energy detection and correlation detection combination method, various satellite mobile communication signal specifications can be accurately detected and recognized. It has been verified that the detection and recognition accuracy of the present disclosure can be greater than 99% (carrier-to-noise ratio C / N≥4.0 dB), which lays an important foundation for subsequent signal single-side demodulation decoding and information analysis processing.

[0114] Referring to Figure 3 The main processing unit of the present disclosure is realized by FPGA system logic programming, such as DDC decimation, resampling and the like, and the TDMA signal detection is realized by the built-in ARM processor of the FPGA system, which can also be realized by an external ARM or CPU and the like. Specifically, the whole process is as follows: the FPGA system transmits the preliminary processed signal to the ARM STM32 to complete the high-level recognition and demodulation; the FPGA system stores the related data in the on-chip storage, and the data in the on-chip storage can also be fed back to the ARM STM32 for analysis; this division of labor makes the FPGA system take advantage of the hardware parallelism to process high-speed signals, and the ARM utilizes the software flexibility to complete intelligent algorithms, realizing efficient cooperation.

[0115] Based on the above technical solutions, the present disclosure comprehensively utilizes the spectrum grading smoothing, threshold self-adaptation and robust detection and the like, realizes the carrier detection and signal parameter measurement of multiple modulation modes (DPSK, pi / 4QPSK, OQPSK, GMSK, 16QAM, 16APSK and the like), multiple symbol rates (8.4KBD~240KBD), and multiple burst frame lengths (5ms, 20ms, 80ms, 90ms and the like); through a large amount of in-depth signal analysis, an prior knowledge base of satellite mobile communication uplink signal specifications is constructed, and the correlation detection and energy detection are utilized to achieve the accurate recognition processing effect of the signal; the present disclosure outputs the signal data after detection and recognition in real time, which can meet the use of subsequent signal processing;

[0116] The present disclosure significantly improves the accurate recognition ability of various satellite mobile communication terminal uplink signals, and the detection and recognition accuracy reaches 99%;

[0117] Compared with the conventional electromagnetic spectrum monitoring scheme, the hardware platform is basically consistent, but the automatic processing capability of detecting and identifying the uplink signals of various satellite mobile communication terminals and the signal specification deep cognitive capability are greatly improved. The convenience of deployment, installation and operation and use is better than various professional monitoring schemes. The hardware cost increases a little, and has low-cost application prospects.

[0118] It should be noted that, for the foregoing method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the present disclosure is not limited by the action sequence described, because according to the present disclosure, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present disclosure.

[0119] In the technical solution of the present disclosure, the acquisition, storage and application of user personal information comply with relevant laws and regulations and do not violate public order and good customs.

[0120] The above is the introduction of the method embodiment, and the present disclosure also provides a multi-mode satellite mobile communication uplink signal real-time detection and identification system 400, which is described with reference to Figure 4 , comprising the following modules:

[0121] The signal judgment module 401 is configured to perform wideband sampling on the received signal to obtain sampling data, perform carrier detection on the sampling data, and determine whether the sampling data contains valid signals. If yes, the next step is entered.

[0122] The channelization module 402 is connected with the signal judgment module 401 and is configured to perform channelization processing on the sampling data to obtain narrowband signals in different narrowband channels corresponding to different satellite systems.

[0123] The detection module 403 is connected with the channelization module 402 and is configured to perform TDMA signal detection on the narrowband signals to obtain signal specifications. The TDMA signal detection includes energy detection and correlation detection.

[0124] Other contents can refer to the foregoing method part, which will not be described here.

[0125] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the described modules can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0126] Figure 5A schematic block diagram of an electronic device 500 that can be used to implement embodiments of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptops, desktops, tablets, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device can also represent various forms of mobile devices, such as personal digital assistants, cellular telephones, smartphones, wearable devices, and other similar computing devices. The components shown here, their connections and relationships, and their functions, are meant to be examples only, and are not intended to limit the implementations of the present disclosure described and / or claimed in this document.

[0127] The electronic device 500 includes a computing unit 501 that can perform various appropriate actions and processes in accordance with a computer program stored in a ROM 502 or a computer program loaded into a RAM 503 from a storage unit 508. In the RAM 503, various programs and data required for the operation of the electronic device 500 can also be stored. The computing unit 501, the ROM 502, and the RAM 503 are connected to each other through a bus 504. An I / O interface 505 is also connected to the bus 504.

[0128] A plurality of components in the electronic device 500 are connected to the I / O interface 505, including: an input unit 506, such as a keyboard, a mouse, and the like; an output unit 507, such as various types of displays, speakers, and the like; a storage unit 508, such as a magnetic disk, an optical disk, and the like; and a communication unit 509, such as a network card, a modem, a wireless communication transceiver, and the like. The communication unit 509 allows the electronic device 500 to exchange information / data with other devices through a computer network, such as the Internet, and / or various telecommunication networks.

[0129] The computing unit 501 can be various general and / or special purpose processing components with processing and computing capabilities. Some examples of the computing unit 501 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The computing unit 501 performs various methods and processes described above, such as the multi-standard satellite mobile communication uplink signal real-time detection and identification method. For example, in some embodiments, the multi-standard satellite mobile communication uplink signal real-time detection and identification method can be implemented as a computer software program, which is tangibly embodied in a machine-readable medium, such as the storage unit 508. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 500 via the ROM 502 and / or the communication unit 509. When the computer program is loaded onto the RAM 503 and executed by the computing unit 501, one or more steps of the multi-standard satellite mobile communication uplink signal real-time detection and identification method described above can be performed. Alternatively, in other embodiments, the computing unit 501 can be configured to perform the multi-standard satellite mobile communication uplink signal real-time detection and identification method by any other appropriate means, such as by means of firmware.

[0130] Various implementations of the systems and techniques described above can be realized in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on a chip (SOC), a programmable logic device (CPLD), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0131] Program code for carrying out methods of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, produces a means for implementing the functions / acts specified in the flowcharts and / or block diagrams. The program code can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, or entirely on a remote machine or server.

[0132] In the context of the present disclosure, a machine-readable medium can be a tangible medium that contains or stores a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include but is not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include one or more lines of electrical connections, portable computer disks, hard disk drives, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fibers, portable compact disc read-only memories (CD-ROMs), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0133] To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having a display device for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0134] The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a user computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN), a wide area network (WAN), and the Internet.

[0135] The computer system can include clients and servers. This relationship can be. The servers are typically remote from the clients with the interactions between them occurring over a communication network. The relationship between a client and a server is one of client-server. The server can be a cloud server, a server of a distributed system, or a server incorporating a blockchain.

[0136] It should be understood that the various forms of flow shown above can be used with reordering, additions, or removals of steps. For example, each of the steps recited in the present disclosure can be performed in parallel, in series, or in a different order, unless otherwise specifically noted, and is not limited to the order recited in this document.

[0137] The specific embodiments described above are not intended to be limiting, and persons skilled in the art will appreciate that various modifications, combinations, sub-combinations and alternatives can be made to the specific embodiments without departing from the spirit and principles of the disclosure. Any further modifications, equivalents, alternatives, and / or improvements made to the specific embodiments described above are intended to fall within the scope of the disclosure.

Claims

1. A method for real-time detection and identification of uplink signals in multi-standard satellite mobile communication, characterized in that, include: The received signal is broadband sampled to obtain sampled data. The sampled data is then subjected to carrier detection to determine whether it contains a valid signal. If it does, proceed to the next step. The sampled data is channelized to obtain narrowband signals in the narrowband channels corresponding to different satellite systems; The narrowband signal is subjected to TDMA signal detection to obtain the signal specifications. The TDMA signal detection includes energy detection and correlation detection. Carrier detection specifically includes the following steps: The sampled data is resampled and subjected to spectral analysis to obtain the analysis results; The analysis results are subjected to carrier detection and signal parameter measurement to obtain signal parameters, which include signal frequency, bandwidth characteristic parameters, signal level, signal-to-noise ratio, and time characteristics. The time characteristics include the end time and the start time of the signal. The calculation of the end time and the start time includes the following steps: Based on the analysis results, a narrow-band signal x(n) is selected, n = 0, 1, ..., N-1. The sliding energy e(m) of the narrow-band signal is expressed by the following formula: Where N and M are both positive integers; using the Haar wavelet basis, wavelet transforms are performed on e(m) at multiple scales to obtain... Let represent the wavelet transform of e(m) at scale s = 2j, where j = 1, 2, ..., J, and J is a positive integer; Calculate the multi-scale wavelet product η(m) based on the sliding energy: Where 1≤J1≤J2≤J; let L=J2-J1+1, if L is odd, and the local minimum point of η(m) is M1, and the local maximum point of η(m) is M2, then the start time of the signal is M1+M / 2, and the end time of the signal is M2-M / 2; if L is even, and the two local maximum points of η(m) with the largest amplitudes are M3 and M4 (M3<M4), then the start time of the signal is M3+M / 2, and the end time of the signal is M4-M / 2.

2. The method for real-time detection and identification of uplink signals in multi-mode satellite mobile communication according to claim 1, characterized in that, The spectral analysis includes a coarse analysis; the coarse analysis includes the following steps: Take the sampled data after 256 resampling points as the first data to be processed; The first data to be processed is subjected to a Hamming window and then a 256-point complex FFT analysis to obtain the first amplitude spectrum. The last 128 points of the first data to be processed are retained, and the last 128 points of the first data to be processed are taken from the resampled data to form the second data to be processed. Determine if the number of times the 256-point complex FFT analysis is performed is equal to 15. If not, treat the second data to be processed as the first data to be processed and proceed to the previous step. If yes, sum the first amplitude spectrum to obtain the total amplitude spectrum of 256 points and proceed to the next step. Divide the total amplitude spectrum by 256*15 to obtain the average amplitude spectrum, and calculate 10*log(average amplitude spectrum) to obtain the logarithmic amplitude.

3. The method for real-time detection and identification of uplink signals in multi-mode satellite mobile communication according to claim 1, characterized in that, The spectral analysis includes fine analysis; the fine analysis specifically includes the following steps: Based on the beginning of each time slot, 8192*14 sampling points of the resampled data are extracted and divided into 14 segments, each segment having 8192 resampled points. Each segment of wide-sampled data is then windowed with a Hamming window and subjected to 8192-point complex FFT analysis to obtain the amplitude spectrum. Summing the 14 amplitude spectra correspondingly yields the sum vector; Divide the sum vector by 8192*14 to obtain the average sum vector, and calculate 10*log(average sum vector) to obtain the logarithmic sum vector.

4. The method for real-time detection and identification of uplink signals in multi-mode satellite mobile communication according to claim 1, characterized in that, The energy detection process includes: The narrowband signal is passed through a preset window, which includes a high threshold and a low threshold. If the start time of the narrowband signal is higher than the high threshold or lower than the low threshold, the narrowband signal is filtered out and it is determined that there is no TDMA signal; otherwise, the narrowband signal is determined to have a TDMA signal, and the TDMA signal is subjected to relevant detection.

5. The method for real-time detection and identification of uplink signals in multi-mode satellite mobile communication according to claim 4, characterized in that, The relevant detection process includes: The TDMA signal is subjected to correlation detection in order to obtain the signal specification corresponding to the TDMA signal by traversing the constructed prior knowledge base; The prior knowledge base includes preamble unique code sequences, signal modulation types, modulation rates, frame periods, and time slot allocation specifications for various satellite mobile communication signal specifications.

6. A real-time detection and identification system for multi-standard satellite mobile communication uplink signals, used to implement the method described in any one of claims 1 to 5, characterized in that, Includes the following modules: The signal determination module is used to perform broadband sampling on the acquired received signal to obtain sampled data, perform carrier detection on the sampled data, and determine whether the sampled data contains a valid signal. If it does, proceed to the next step. A channelization module, connected to the signal determination module, is used to perform channelization processing on the sampled data to obtain narrowband signals in the narrowband channels corresponding to different satellite systems. The detection module, connected to the channelization module, is used to perform TDMA signal detection on the narrowband signal to obtain the signal specifications. The TDMA signal detection includes energy detection and correlation detection.

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