CN115441931A - Satellite-ground cooperative interference detection and avoidance system - Google Patents
Satellite-ground cooperative interference detection and avoidance system Download PDFInfo
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Abstract
The invention discloses a satellite-ground cooperative interference detection and avoidance system, and belongs to the technical field of satellite anti-interference communication. The invention comprises a frequency hopping control unit, a frequency sweeping control unit and an interference detection unit. The frequency hopping bandwidth is swept in segments, the interference condition of each segment is detected, and interference control information is generated; one path of interference control information is transmitted to a ground terminal through a satellite-borne modulator, and the other path of interference control information is directly transmitted to a frequency hopping control unit; and the frequency hopping control unit and the ground terminal realize satellite-ground synchronous switching of frequency hopping patterns according to the interference control information and avoid interference. The invention is particularly suitable for the condition that partial frequency band, single tone, multi-tone and comb-shaped interference with constant or slow frequency point change in a certain time exists in a satellite communication link. The invention has simple protocol and implementation mode and less resource occupation, can effectively solve various interference patterns in the satellite communication system and achieves the effect of anti-interference.
Description
Technical Field
The invention belongs to the technical field of frequency hopping anti-interference communication in satellite communication, and particularly relates to a satellite-ground cooperative interference detection and avoidance system which can cope with various interference patterns of channels, such as tones, polyphones, combs, partial frequency bands and the like, which are unintentional or malicious, and have constant or slowly-changing central frequency within a certain time.
Background
If the satellite-borne frequency hopping demodulator needs to realize single-machine one-way anti-interference communication, two modes are provided. One approach is to require dedicated interference detection equipment, plus complex system control protocols, which increases overall transmission costs and system processing complexity; the other method is that a satellite-borne demodulator is needed to complete a complex interference detection and suppression algorithm, the algorithm processing complexity is high, the resource occupation amount is large, and the cost and the risk of a single machine are increased.
Disclosure of Invention
The invention aims to avoid the defects in the background technology and provides a satellite-ground cooperative interference detection and avoidance system. The method has the characteristics of low processing complexity, simple principle and algorithm, small resource occupation amount and the like, and can effectively avoid various interference patterns in satellite-to-ground links.
The purpose of the invention is realized by the following steps:
the utility model provides a system is detected and dodged in interference of satellite-ground coordination, includes sweep frequency control unit 1, interference detection unit 2, frequency hopping control unit 3, ground terminal 4, wherein:
the frequency sweeping control unit 1 is used for carrying out debounce operation on an input frequency hopping signal and debounce the frequency hopping signal to an intermediate frequency fixed frequency signal;
the interference detection unit 2 is used for down-converting the intermediate frequency fixed frequency signal to the baseband, and performing low-pass filtering operation to divide the frequency hopping bandwidth into baseband bandwidth signals S 1 (n)、S 2 (n)、…、S N (n); for each segment of baseband bandwidth signal S i (N) performing a power calculation, i =1, 2.., N, and comparing the power calculation result with a set interference threshold power P th Make a comparisonDetermining whether the segment of spectrum is interfered; the system is also used for generating interference control information by adding a fixed value to the current TOD time reference and an interference detection result, dividing the interference control information into two paths, wherein one path is transmitted to the ground terminal 4 through the satellite-borne modulator, and the other path is transmitted to the frequency hopping control unit 3;
the frequency hopping control unit 3 determines whether to execute interference avoidance operation according to the interference control information and the current TOD time reference, and the frequency hopping signal after the interference avoidance operation is executed is subjected to frequency hopping to an intermediate frequency fixed frequency signal for subsequent demodulation and decoding;
the ground terminal 4 performs the same operation as the frequency hopping control unit 3, thereby realizing satellite-to-ground synchronous change of the frequency hopping pattern and avoiding the interfered frequency hopping bandwidth.
Furthermore, the sweep frequency control unit 1 is composed of a segmented sweep frequency control module, a first debounce local oscillator generation module and a first debounce module;
the segmented sweep frequency control module divides the frequency hopping bandwidth into N segments, wherein N =2 m ，m>1, at every other hop of duration Th, a segmented frequency sweep control module sequentially generates a center frequency control word of each segment of bandwidth;
the first debounce local oscillator generating module generates local oscillator signals required by debounce according to the frequency control words transmitted by the segmented frequency sweeping control module;
the first de-hopping module de-hops the input frequency hopping signal according to the local oscillator signal generated by the first de-hopping local oscillator generating module, and sequentially generates an intermediate frequency fixed frequency signal M 1 (n)、M 2 (n)、…M N (n)。
Further, the frequency hopping control unit 3 is composed of an interference avoidance control module, a frequency hopping pattern mapping module, a second debounce local oscillator generation module and a second debounce module;
the interference avoidance control module judges which sections in the frequency hopping bandwidth are interfered according to the received interference control information and controls the frequency hopping local oscillator to switch to avoid the interference;
the frequency hopping pattern mapping module generates a frequency control word according to the current TOD time reference information;
the second debounce local oscillator generating module receives the control information transmitted by the interference avoidance control module and the frequency control word of the frequency hopping pattern generating module, and if the frequency hopping bandwidth corresponding to the current frequency control word is interfered, the frequency control word is forcibly switched into the frequency hopping frequency band corresponding to the frequency control word which is appointed in advance and is not interfered; the time of forced switching of the frequency control word is determined by TOD time reference in the interference control information;
and the second de-hopping module performs de-hopping operation on the input frequency hopping signal by using a de-hopping local oscillator generated after the frequency control word is switched to generate an intermediate frequency fixed frequency signal for subsequent demodulation and decoding.
Further, the interference detection unit 2 includes a down-conversion filtering module, a power statistics module and an interference judgment and framing module;
the down-conversion filtering module is used for inputting the intermediate frequency fixed frequency signal M 1 (n)、M 2 (n)、…M N (n) sequentially down-converting to zero frequency, and then performing low-pass filtering operation to obtain a baseband bandwidth signal S 1 (n)、S 2 (n)、…、S N (n)；
The power statistical module sequentially counts the average power of the baseband bandwidth signals, and when the high m bits of the frequency control word of the frequency sweep control unit 1 are equal to the high m bits of the frequency control word of the frequency hopping control unit 3, average power calculation is not carried out; when the two are not equal, the average power of each baseband bandwidth signal is calculated according to the following formula
In the above equation, each hop contains K data, I and Q are the in-phase and quadrature components of the baseband data, respectively, I =1, 2.. N;
in the frequency sweep process, the average power of each section of baseband bandwidth signal is calculated for multiple times, and the interference judgment and framing module leads the average powers of each section of baseband bandwidth signal to be equal to the interference thresholdPower P th Comparing, when the average power over 80% is larger than the interference threshold power P th When the signal is in a signal state, marking the segment of baseband bandwidth signal as 1 to indicate that the segment of baseband bandwidth signal is interfered, otherwise marking the segment of baseband bandwidth signal as 0 to indicate that the segment of baseband bandwidth signal is not interfered, wherein the marks of the N segments of baseband bandwidth signals form N-bit mark information; in addition, the interference judging and framing module receives the current TOD time reference, adds a fixed value to the current TOD time reference to serve as interference avoidance TOD time reference information at the moment of interference avoidance action, and the fixed value is the sum of satellite-to-ground transmission delay and signal processing delay; then, the interference avoidance TOD time reference information and the N-bit mark information form a format frame, the format frame is divided into two paths, one path is transmitted to the frequency hopping control unit 3, and the other path is transmitted to the ground terminal 4 through the satellite-borne modulator.
Compared with the background technology, the invention has the following advantages:
1. the invention does not need additional interference detection and processing equipment, thereby reducing the complexity and the cost of the system.
2. The invention does not use complex interference detection and suppression algorithm, has simple algorithm processing, does not need higher layer protocol support and occupies less resources.
3. The invention can effectively resist various interference patterns such as single tone, multi-tone, comb, partial frequency band and the like with constant or slowly-changed central frequency point within a certain time by changing the frequency hopping frequency point in a satellite-ground cooperation manner.
In a word, the method has the advantages of simple algorithm implementation, small occupied resource amount and the like, and is particularly suitable for frequency hopping anti-interference communication in satellite communication.
Drawings
FIG. 1 is a block diagram of the components of the present invention.
Fig. 2 is a schematic flow chart of satellite-ground cooperative interference avoidance.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
Referring to fig. 1, a satellite-ground cooperative interference detection and avoidance system includes a frequency sweep control unit 1, an interference detection unit 2, a frequency hopping control unit 3, and a ground terminal 4.
The frequency sweep control unit 1 performs debounce operation with the input frequency hopping signal, and the frequency hopping signal is debounced to an intermediate frequency fixed frequency signal. The specific implementation mode is as follows: the segmented sweep frequency control module divides the frequency hopping bandwidth into N segments, wherein N =2 m (m > 1). And the segmented frequency sweeping control module sequentially generates a central frequency control word of each segment of bandwidth every Th (Th is the duration of one hop). And the frequency hopping local oscillator generating module generates local oscillator signals required by the de-hopping according to the frequency control words transmitted by the segmented frequency sweeping control module. The first debounce module is used for debounce the input frequency hopping signal according to the local oscillator signal generated by the debounce local oscillator generation module, and sequentially generates an intermediate frequency fixed frequency signal M 1 (n)、M 2 (n)、…M N And (N) N sections.
The down-conversion filtering module in the interference detection unit 2 down-converts the intermediate frequency fixed-frequency signal to zero frequency, and performs low-pass filtering operation to obtain a baseband bandwidth signal S 1 (n)、S 2 (n)、…、S N (n) in the formula (I). The power statistic module in the interference detection unit 2 counts the baseband bandwidth signal S of each segment i (n) carrying out power calculation for multiple times, and comparing the power calculation result with the set interference threshold power P th And comparing, and determining whether the frequency spectrum is interfered or not according to the comparison results of multiple times, wherein 1 represents interfered, 0 represents not interfered, and the marks of the N sections of baseband bandwidth signals form an N-bit interference detection result. The interference judging and framing module adds a fixed value to the current TOD (Time of Date) and generates interference control information with the interference detection result, one path is transmitted to the ground terminal 4 through the satellite-borne modulator, and the other path is directly transmitted to the frequency hopping control unit 3.
Referring to fig. 2, the frequency hopping control unit 3 and the ground terminal 4 respectively determine whether to perform interference avoidance and switch to an undisturbed frequency band in the same manner according to the interference control information and the current TOD. The frequency hopping control unit 3 realizes the switching of frequency control words, and the frequency hopping signal after executing the interference avoidance operation is subjected to frequency hopping to an intermediate frequency fixed frequency signal for subsequent demodulation and decoding.
The brief working principle of the system is as follows:
the frequency-sweeping control unit 1 divides the frequency-hopping bandwidth into N sections, and each hop sequentially carries out the hopping on one section of the frequency-hopping bandwidth to the intermediate frequency fixed frequency. The interference detection unit 2 down-converts each section of the intermediate frequency bandwidth signal to a baseband, and performs average power calculation and interference detection discrimination for a plurality of times. And according to the results of multiple interference detection and judgment, representing the interfered information of each section in the whole frequency hopping bandwidth by using N bits. And adding a fixed value to the current TOD value to serve as the starting time of satellite-ground interference avoidance, generating interference control information by combining the interfered information, transmitting the interference control information to a frequency hopping control unit 3 of the satellite-borne demodulator, and transmitting the interference control information to the ground terminal through a downlink channel of the satellite-borne modulator. In frequency hopping communication, the ground terminal 4 and the satellite-borne demodulator share the same TOD and frequency hopping pattern, the ground terminal 4 and the frequency hopping control unit 3 of the satellite-borne demodulator synchronously and consistently switch the interfered frequency point to an undisturbed frequency band according to interference control information, and the switching time is determined by the TOD in the interference control information, so that the satellite and the ground can simultaneously change the frequency hopping frequency point and avoid interference.
In a word, the frequency hopping bandwidth is swept in segments, the interfered condition of each segment is detected, and interference control information is generated; one path of interference control information is transmitted to a ground terminal through a satellite-borne modulator, and the other path of interference control information is directly transmitted to a frequency hopping control unit; and the frequency hopping control unit and the ground terminal realize satellite-ground synchronous change of frequency hopping patterns according to the interference control information and avoid interference. The invention is particularly suitable for the condition that partial frequency band, single tone, multi-tone and comb-shaped interference with constant or slow frequency point change in a certain time exists in a satellite communication link. The invention has simple protocol and implementation mode and less resource occupation, can effectively solve various interference patterns in the satellite communication system and achieves the effect of anti-interference.
Claims (4)
1. The utility model provides a system is detected and dodged in interference of satellite-ground coordination, which is characterized in that, includes sweep frequency control unit (1), interference detection unit (2), frequency hopping control unit (3), ground terminal (4), wherein:
the frequency sweeping control unit (1) is used for carrying out debounce operation on an input frequency hopping signal and debounce the frequency hopping signal to an intermediate frequency fixed frequency signal;
the interference detection unit (2) is used for down-converting the intermediate frequency fixed frequency signal to a baseband, performing low-pass filtering operation, and sequentially dividing the frequency hopping bandwidth into baseband bandwidth signals S 1 (n)、S 2 (n)、…、S N (n); for each segment of baseband bandwidth signal S i (N) performing power calculation, i =1, 2.., N, and comparing the power calculation result with a set interference threshold power P th Comparing to determine whether the frequency spectrum is interfered; the system is also used for generating interference control information by adding a fixed value to the current TOD time reference and an interference detection result, dividing the interference control information into two paths, transmitting one path to the ground terminal (4) through the satellite-borne modulator, and transmitting the other path to the frequency hopping control unit (3);
the frequency hopping control unit (3) determines whether to execute interference avoidance operation according to the interference control information and the current TOD time reference, and the frequency hopping signal after executing the interference avoidance operation is subjected to frequency hopping to an intermediate frequency fixed frequency signal for subsequent demodulation and decoding;
the ground terminal (4) executes the same operation as the frequency hopping control unit (3), thereby realizing the star-to-ground synchronous change of the frequency hopping pattern and avoiding the interfered frequency hopping bandwidth.
2. The satellite-ground cooperative interference detection and avoidance system according to claim 1, wherein the sweep frequency control unit (1) is composed of a segmented sweep frequency control module, a first debounce local oscillator generation module and a first debounce module;
the segmented sweep frequency control module divides the frequency hopping bandwidth into N segments, wherein N =2 m ，m>1, at every other hop of duration Th, a segmented frequency sweep control module sequentially generates a central frequency control word of each segment of bandwidth;
the first debounce local oscillator generating module generates local oscillator signals required by debounce according to the frequency control words transmitted by the segmented frequency sweeping control module;
the first de-hopping module de-hops the input frequency hopping signal according to the local oscillator signal generated by the first de-hopping local oscillator generation module, and sequentially generates an intermediate frequency fixed frequency signal M 1 (n)、M 2 (n)、…M N (n)。
3. The system for detecting and avoiding interference in satellite-to-ground coordination according to claim 2, wherein the frequency hopping control unit (3) is composed of an interference avoidance control module, a frequency hopping pattern mapping module, a second debounce local oscillator generation module and a second debounce module;
the interference avoidance control module judges which sections in the frequency hopping bandwidth are interfered according to the received interference control information and controls the frequency hopping local oscillator to switch to avoid the interference;
the frequency hopping pattern mapping module generates a frequency control word according to the current TOD time reference information;
the second debounce local oscillator generation module receives the control information transmitted by the interference avoidance control module and the frequency control word of the frequency hopping pattern generation module, and if the frequency hopping bandwidth corresponding to the current frequency control word is interfered, the frequency control word is forcibly switched into a frequency hopping frequency band corresponding to a frequency control word which is appointed in advance and is not interfered; the forced switching time of the frequency control word is determined by the TOD time reference in the interference control information;
and the second de-hopping module performs de-hopping operation on the input frequency hopping signal by using a de-hopping local oscillator generated after the frequency control word is switched to generate an intermediate frequency fixed frequency signal for subsequent demodulation and decoding.
4. The system for satellite-to-ground cooperative interference detection and avoidance according to claim 3, wherein the interference detection unit (2) comprises a down-conversion filtering module, a power statistics module and an interference determination and framing module;
the down-conversion filtering module is used for inputting an intermediate frequency fixed-frequency signal M 1 (n)、M 2 (n)、…M N (n) sequentially down-converting to zero frequency, and then performing low-pass filtering operation to obtain a baseband bandwidth signal S 1 (n)、S 2 (n)、…、S N (n)；
The power statistical module sequentially counts the average power of the baseband bandwidth signals, when the high m bits of the frequency control word of the sweep frequency control unit (1) are equal toWhen the frequency control word of the frequency hopping control unit (3) has m high bits, the average power is not calculated; when the two are not equal, the average power of each baseband bandwidth signal is calculated according to the following formula
In the above equation, each hop contains K data, I and Q are the in-phase and quadrature components of the baseband data, respectively, I =1, 2.. N;
in the frequency sweep process, the average power of each section of baseband bandwidth signal is calculated for multiple times, and the interference judgment and framing module enables the average powers of each section of baseband bandwidth signal to be equal to the interference threshold power P th Comparing, when the average power exceeding 80% is larger than the interference threshold power P th When the signal is in a signal state, marking the segment of baseband bandwidth signal as 1 to indicate that the segment of baseband bandwidth signal is interfered, otherwise marking the segment of baseband bandwidth signal as 0 to indicate that the segment of baseband bandwidth signal is not interfered, wherein the marks of the N segments of baseband bandwidth signals form N-bit mark information; in addition, the interference judging and framing module receives the current TOD time reference, adds a fixed value to the current TOD time reference to serve as interference avoidance TOD time reference information at the moment of interference avoidance action, and the fixed value is the sum of satellite-to-ground transmission delay and signal processing delay; and then, forming a format frame by the interference avoidance TOD time reference information and the N-bit mark information, dividing the format frame into two paths, transmitting one path of the format frame to a frequency hopping control unit (3), and transmitting the other path of the format frame to a ground terminal (4) through a satellite-borne modulator.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5970055A (en) * | 1996-08-24 | 1999-10-19 | Samsung Electronics Co., Ltd. | Radio communication system adapting time division duplexing/frequency hopping |
| CN106656372A (en) * | 2016-12-12 | 2017-05-10 | 西安空间无线电技术研究所 | Frequency band interference detection method for frequency hopping system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5970055A (en) * | 1996-08-24 | 1999-10-19 | Samsung Electronics Co., Ltd. | Radio communication system adapting time division duplexing/frequency hopping |
| CN106656372A (en) * | 2016-12-12 | 2017-05-10 | 西安空间无线电技术研究所 | Frequency band interference detection method for frequency hopping system |
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