阅读说明：本技术 一种基于基站解码的卫星转发器干扰定位新方法 (Novel satellite transponder interference positioning method based on base station decoding ) 是由 李安平 唱亮 魏梅英 赵哲 张小飞 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种基于基站解码的卫星转发器干扰定位新方法,用于解决基站串扰型卫星上行站干扰的问题。本发明方法包括：对卫星转发信号的频谱图进行时频分析,根据带宽和频谱特征查找是否存在串扰GSM信号；对存在的GSM信号的基站小区识别码解码；根据基站小区识别码映射基站位置；在基站位置处查找疑似干扰源,定位存在基带传输线缆泄漏的卫星地球站。本发明打破传统双星定位方法定位干扰源的思路,可快速、准确地完成干扰卫星上行站的定位和排查,并能取得良好的干扰源定位效果。(The invention discloses a novel interference positioning method for a satellite transponder based on base station decoding, which is used for solving the problem of base station crosstalk type satellite uplink station interference. The method comprises the following steps: performing time-frequency analysis on a spectrogram of the satellite forwarding signal, and searching whether a crosstalk GSM signal exists according to bandwidth and spectrum characteristics; decoding the base station cell identification code of the existing GSM signal; mapping the position of the base station according to the cell identification code of the base station; and (4) searching suspected interference sources at the base station position, and positioning the satellite earth station with the leakage of the baseband transmission cable. The method breaks through the idea of positioning the interference source by the traditional double-satellite positioning method, can quickly and accurately complete the positioning and the troubleshooting of the interference satellite uplink station, and can obtain a good interference source positioning effect.)

1. A satellite transponder interference positioning method based on base station decoding is characterized by comprising the following steps:

step 1, collecting signals from a satellite received by a user, carrying out time-frequency analysis on a spectrogram of the signals, judging whether unequally spaced TDMA signals exist or not according to bandwidth and spectrogram characteristics, if so, indicating that crosstalk GSM signals are detected and a satellite transponder is interfered, continuing the next step, otherwise, not continuing the following steps; TDMA represents time division multiple access;

step 2, decoding a base station cell identification code CGI of the crosstalk GSM signal;

step 3, mapping the position of the base station cell according to the identification code CGI;

and 4, using base station cell identification code decoding equipment to verify the base station cell information at the base station cell position so as to confirm that the mapping of the base station position is correct, and searching satellite earth stations nearby the base station cell position, wherein the found satellite earth stations are earth stations with baseband transmission cable leakage.

2. The method according to claim 1, wherein in step 4, after confirming that the mapping of the base station position is correct, the satellite earth station is searched within a range of 1-2km near the base station position.

Technical Field

The invention relates to the technical field of radio management, in particular to a method for positioning by adopting a brand-new technology under the condition that a satellite transponder is interfered by a mobile communication base station to enter the transponder and generate interference on the transponder.

Background

In recent years, with the rapid increase of mobile communication services, the number of base stations in various regions is increasing dramatically, and in addition to the significant increase of the number of 3G/4G base stations, the GSM (global system for mobile communications) base stations of two mobile and public communications operators are expanding. With the explosion of satellite communication services, the number of satellite earth stations is also rapidly increasing, and thus the problem of electromagnetic compatibility due to improper location is increasingly highlighted. But because the directivity of the satellite earth station transmitting antenna is extremely strong, the mobile communication service is generally not influenced; however, if the base station is close to the satellite earth station and the L-band transmission cable of the earth station is not well shielded, the base station signal may be interfered into the transmission cable and transmitted to the satellite, as shown in fig. 1, the resource of the satellite transponder may be occupied, and the rights and interests of the legitimate users are difficult to be guaranteed. Therefore, an effective technical solution must be found to accurately determine the geographical location of the base station crosstalk so as to be able to quickly complete the interference elimination.

At present, the interference to the transponder in China adopts a double-star and three-star positioning technology, namely, the principle of reversely deducing an interference source by calculating the TDoA (time difference of arrival) and FDoA (frequency difference of arrival) values generated by the interference through two qualified satellites. The precondition of this method is that the interference signal at the same frequency point comes from the same emission source, and for the signals with Time Division Multiple Access (TDMA) characteristics like GSM, the TDoA and FDoA values of their corresponding emission time sequence cannot be calculated, so that positioning cannot be realized. Methods for inferring the geographic location in this manner by decoding the base station information have not been studied. The current close papers adopt methods such as TDoA and FDoA, or methods using multiple tdoas. For example, reference 1 (lieanping wilimei liuman, a research on a method for locating an interference source by using multiple TDOA values generated by perturbation of two geostationary orbit satellites, [ M ]. china radio, pages 60 to 63 in 11 th of 2019) proposes a new method for locating an interference source by using a factor that two geostationary orbit satellites move relative to each other to cause different arrival time differences at different moments. The method comprises the steps of firstly analyzing and calculating the change rule of time difference TDoA (time domain analysis) generated by different signals through two stationary orbit satellites due to satellite motion caused by perturbation and control of the satellites at different moments, researching a method for accurately estimating the time difference generated by the signals through different channels under a stable link of the stationary orbit satellites, and designing an algorithm for reversely deducing a corresponding earth surface area according to an estimated value; then, a cluster of curves is obtained through estimation in different time periods, and a positioning ellipse based on confidence coefficient is finally obtained by combining with the statistical probability distribution characteristic; and finally, simulation analysis is carried out on the positioning accuracy which can be realized by the satellite under the condition of different motion radiuses. The reference document 2 (updated by the tenuous sunpeng of zhuiguo, an overview of a satellite interference source positioning method [ C ]. fifteenth annual meeting of satellite communication academic prosecution, 2019) records that with the arrival of an information-oriented society, the international and domestic radio communication technology is rapidly developed, the demand of users on radio communication is continuously expanded, and the satellite communication is widely applied to the fields of international communication, mobile communication, broadcast television and the like due to the advantages of wide frequency band, large capacity, suitability for various services and the like, however, due to the existence of an interference source, the satellite communication has a serious safety problem, and therefore, the method has very important significance for quickly and effectively positioning the target position of the interference source. The passive positioning technology has the advantages of good concealment, long working distance and the like, and currently occupies an increasingly critical position in military and civil systems, and is a research hotspot in the field of current positioning. Reference 2 mainly introduces the principles and algorithms of a satellite interference source positioning system and several positioning methods, a new algorithm and a new technology of the satellite positioning system, and finally proposes a concept for future development of satellite interference source positioning. In reference 3 (Zhao hong Wei Liu Heng, a compressed sensing DOA estimation method [ M ] for satellite interference source positioning, firepower and command control, page 25-28 of 10 th year 2016), aiming at the poor practical application performance of the traditional direction finding method, a satellite interference source positioning method based on Compressed Sensing (CS) is provided, a compressed sensing DOA estimation model is established according to the space sparsity of an interference signal azimuth, a signal subspace and the conjugate symmetry characteristic of a matrix are approximated by high-order power of a covariance matrix, and the DOA estimation is carried out by utilizing the lower left corner column vector under the main diagonal of the high-order power matrix. Simulation experiments prove that the method of the reference file 3 does not need to know the number of interference sources, has higher precision and better resolution, can meet the estimation of coherent interference signals, and has certain reference significance for the application of compressed sensing DOA estimation in satellite interference source positioning.

Base station crosstalk type satellite uplink station interference is a special satellite interference mode, when crosstalk occurs, a satellite earth station couples nearby base station information to a transmitting unit of the satellite earth station, a plurality of uplink signals are arranged on a public frequency band of an on-satellite transponder and do not correspond to the earth station one by one, crosstalk base station signals are narrow-band signals and are superposed on normal satellite broadband signals, and because the satellite forwarding signals are time division, the uplink signals in a certain time period are difficult to separate, and accurate FDoA and TDoA cannot be calculated, the effect of the traditional two-satellite positioning method is generally poor. Therefore, there is a need to further design new positioning techniques that are suitable for base station crosstalk to repeater interference.

Disclosure of Invention

The invention provides a novel method for satellite transponder interference positioning based on base station decoding, which is a practical method for checking interference of satellite uplink station base station crosstalk type and achieves good effect in practice.

The invention provides a satellite transponder interference positioning method based on base station decoding, which comprises the following steps:

step 1, collecting signals from a satellite received by a user, carrying out time-frequency analysis on a spectrogram of the signals, judging whether a GSM signal exists according to bandwidth and spectrogram characteristics and combining with broadcast channel blind analysis, if so, indicating that a crosstalk GSM signal is detected and a satellite transponder is interfered, continuing the next step, otherwise, not continuing the following steps;

step 2, decoding a base station cell identification code CGI of the crosstalk GSM signal;

step 3, mapping the position of the base station cell according to the identification code CGI;

and 4, using base station cell identification code decoding equipment to verify the base station cell information at the base station cell position so as to confirm that the mapping of the base station position is correct, and searching satellite earth stations nearby the base station cell position, wherein the found satellite earth stations are earth stations with baseband transmission cable leakage.

Compared with the prior art, the satellite transponder interference positioning method based on base station decoding has the following advantages and positive effects: the method breaks through the conventional technical thought of reversely deducing the interference source through TDoA and FDoA at present, firstly identifies the crosstalk GSM signal, and then carries out position mapping after analyzing the cell identification code of the base station, thereby realizing the positioning of the interference source. The method is completely different from the method for reversely deducing the interference source through TDoA and FDoA in the prior art, can quickly and accurately complete the positioning and the troubleshooting of the interference satellite uplink station aiming at the crosstalk scene of the satellite uplink signal base station, effectively solves the technical difficulty that the special interference is difficult to position, and realizes a brand-new and non-traditional positioning technology for coupling the base station to the satellite transponder. Through inspection, the method can obtain a good interference source positioning effect in an actual scene.

Drawings

FIG. 1 is a schematic diagram of a scenario of satellite uplink signal base station crosstalk;

FIG. 2 is a flow chart of the base station crosstalk-type interference positioning according to the present invention;

FIG. 3 is a diagram of the spectral and time-frequency characteristics of a GSM signal;

FIG. 4 is a CGI information diagram of a GSM signal;

fig. 5 is a schematic diagram of mapping out shot point locations.

Detailed Description

The technical solution of the present invention is described below with reference to the accompanying drawings and examples.

As shown in fig. 1, in a satellite uplink signal base station crosstalk scenario, GSM signals are modulated by a satellite earth station and transmitted together by a transmitting antenna to a satellite. Because GSM only has a signal of a broadcast channel in a normal state, and the signal of the broadcast channel is generally a TDMA signal, a conventional two-satellite positioning signal cannot be positioned, and a few of the more novel two-satellite positioning systems have functions of TDMA signal timeslot parameter estimation, signal reconstruction and the like, but the positioning effect and reliability are still not as good as those of conventional signals, so the two-satellite positioning method cannot be used as a preferred scheme for such scene interference positioning.

In the invention, in a situation that a satellite transmits a base station signal of crosstalk to a user in a satellite uplink signal base station crosstalk scene, the satellite transmits the signal of the crosstalk to the user, and the satellite transmitting signal received by the user contains the signal of the crosstalk base station, so that the invention particularly identifies and processes the signal. The signal of the GSM broadcast channel contains global cell identification Code (CGI) information, the identification code is globally unique, so that corresponding information can be obtained by a method for analyzing the GSM signal identification code, and then the position of the cell identification code corresponding to the base station is obtained by means of a network management side worker reference of an operator or a search tool of a third party, so that the satellite earth station is positioned nearby the base station, the positioning position of the base station can be used as the position of the satellite uplink station, the distance between the satellite earth station and the base station is about 1-2km generally, the error is small enough for positioning the satellite uplink station, and the difficulty in searching the uplink station cannot be caused. Therefore, a flow of the method for positioning satellite transponder interference based on base station decoding according to the present invention is shown in fig. 2, and is described below with 4 steps.

Step 1: and (4) performing signal judgment on the received satellite forwarding signal at the user side, and judging whether the satellite forwarding signal is a GSM signal.

The GSM signal is characterised by its spectral shape as a digital signal and is observed on a time-frequency diagram as a non-equally spaced TDMA signal, since its 8 time slots are generally not fully occupied. As shown in fig. 3, the frequency spectrum and time-frequency diagram features of the GSM signal are shown, from which the center frequency of the base station can be accurately obtained, and whether the GSM signal is obtained is determined according to the bandwidth and frequency diagram features. On this basis, the base station decoder will decode according to the center frequency (channel).

The method comprises the steps of collecting signals from a satellite, carrying out time-frequency analysis on a frequency spectrogram of the signals, judging whether non-equidistant TDMA signals exist, if so, indicating that a satellite transponder is interfered and an interference source needs to be searched, and if not, determining that the condition that the satellite transponder is interfered is not detected currently. When a cross-talk GSM signal is detected, the center frequency of the base station is also obtained from the time-frequency analysis accordingly.

Step 2: the identification code of the GSM signal is decoded.

For the GSM system, the global cell identity (CGI) includes information such as a country code (MCC), a network code (MNC), a region code (LAC), and a cell number (CI), as shown in fig. 4. For GMSK (gaussian minimum shift keying) signals of the GSM system, the signal-to-noise ratio required for decoding should be greater than 5.5dB, and in practical applications, stable decoding can be basically guaranteed above 6 dB. At present, there are two kinds of optional decoding devices, one is to use an engineering test handset, and the other is to use a special base station decoder.

And step 3: and mapping the position of the base station.

After the CGI of the base station cell is obtained, the location of the base station is generally searched and mapped by using an operator or a commercial resource of a third party, and two search methods are feasible, the first method is based on base station data given by an operator network management side, and needs to be coordinated by related administrative departments across departments, so that certain uncertainty is generated, and interference searching and locating efficiency is affected. The other idea is to utilize the commercial resources of a third party, such as the resources of a converged base station, a GPSSPG base station for query and the like, and the method of the idea is strong in query real-time performance and high in efficiency. A typical base station location map is shown in fig. 5.

And 4, step 4: and searching a suspected interference source.

After the position of the base station cell is obtained, the location can be reached for searching, and the base station information is further verified by the decoding equipment carrying the base station identification code, so that the mapping link of the base station position is confirmed to be correct. After the satellite earth station is reached to the vicinity of the positioning point, the satellite earth station should be found within 1-2 kilometers of the vicinity in principle, and the search range can be further enlarged if the satellite earth station is not found. The earth station should be one where there is leakage of the baseband transmission cable.