A satellite-ground coordinated interference detection and avoidance system

Abstract

The present invention discloses a satellite-ground coordinated interference detection and avoidance system, which belongs to the field of satellite anti-interference communication technology. The present invention includes a frequency hopping control unit, a frequency sweeping control unit, and an interference detection unit. The present invention performs segmented frequency sweeping on the frequency hopping bandwidth, detects the interference situation of each segment, and generates interference control information; the interference control information is transmitted to the ground terminal through the satellite-borne modulator one way and directly transmitted to the frequency hopping control unit one way; the frequency hopping control unit and the ground terminal implement satellite-ground synchronous switching of the frequency hopping pattern according to the interference control information to avoid interference. The present invention is particularly suitable for situations in which there are partial frequency bands, single tones, multiple tones, and comb-shaped interferences in the satellite communication link whose frequency points remain unchanged or change slowly within a certain period of time. The protocol and implementation method of the present invention are simple, and the resource occupation is small. It can effectively solve the various interference patterns existing in the satellite communication system and achieve the anti-interference effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of frequency hopping anti-interference communication in satellite communication, and in particular refers to a satellite-ground coordinated interference detection and avoidance system, which can cope with various interference patterns such as single-tone, multi-tone, comb-shaped, partial frequency band, etc., in which the channel has unintentional or malicious interference and the center frequency remains unchanged or changes slowly within a certain period of time. Background Art

[0002] There are two ways to achieve single-machine one-way anti-interference communication with a satellite-borne frequency-hopping demodulator. One way requires dedicated interference detection equipment and complex system control protocols, which increases the overall launch cost and system processing complexity. The other way requires a satellite-borne demodulator to complete a complex interference detection and suppression algorithm, which has high algorithm processing complexity and large resource usage, increasing the cost and risk of a single machine. Summary of the invention

[0003] The purpose of the present invention is to avoid the deficiencies in the above-mentioned background technology and provide a satellite-to-ground coordinated interference detection and avoidance system. The present invention has the characteristics of low processing complexity, simple principle and algorithm, and low resource occupation, and can effectively avoid various interference patterns existing in satellite-to-ground links.

[0004] The object of the present invention is achieved in that:

[0005] A satellite-ground coordinated interference detection and avoidance system comprises a frequency scanning control unit 1, an interference detection unit 2, a frequency hopping control unit 3, and a ground terminal 4, wherein:

[0006] The frequency sweep control unit 1 is used to perform a de-hopping operation on the input frequency hopping signal, and de-hop the frequency hopping signal to an intermediate frequency fixed frequency signal;

[0007] The interference detection unit 2 is used to down-convert the intermediate frequency fixed frequency signal to the baseband, and perform a low-pass filtering operation to divide the frequency hopping bandwidth into baseband bandwidth signals S1(n), S2(n), ..., S N (n); used for each baseband bandwidth signal S i (n) Perform power calculation, i = 1, 2, ..., N, and compare the power calculation result with the set interference threshold power P th Compare to determine whether the spectrum is interfered; also used to add a fixed value to the current TOD time reference and the interference detection result to generate interference control information, and divide the interference control information into two paths, one is transmitted to the ground terminal 4 through the satellite modulator, and the other is transmitted to the frequency hopping control unit 3;

[0008] The frequency hopping control unit 3 determines whether to perform the interference avoidance operation according to the interference control information and the current TOD time reference, and de-hops the frequency hopping signal after the interference avoidance operation to the intermediate frequency fixed frequency signal for subsequent demodulation and decoding;

[0009] The ground terminal 4 performs the same operation as the frequency hopping control unit 3, thereby achieving satellite-ground synchronization to change the frequency hopping pattern and avoid interference with the frequency hopping bandwidth.

[0010] Further, the frequency sweep control unit 1 is composed of a segmented frequency sweep control module, a first de-hopping local oscillator generation module and a first de-hopping module;

[0011] The segmented frequency sweep control module divides the frequency hopping bandwidth into N segments, N = 2 m , m>1, every hop duration Th, the segmented frequency sweep control module generates the center frequency control word of each bandwidth in turn;

[0012] The first de-hopping local oscillator generating module generates the local oscillator signal required for de-hopping according to the frequency control word transmitted by the segmented frequency sweeping control module;

[0013] 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 generates intermediate frequency fixed frequency signals M1(n), M2(n), ...M N (n).

[0014] Further, the frequency hopping control unit 3 is composed of an interference avoidance control module, a frequency hopping pattern mapping module, a second de-hopping local oscillator generation module and a second de-hopping module;

[0015] The interference avoidance control module determines which segments in the frequency hopping bandwidth are interfered with based on the received interference control information, and controls the switching of the frequency hopping local oscillator to avoid interference;

[0016] The frequency hopping pattern mapping module generates a frequency control word according to the current TOD time reference information;

[0017] The second de-hopping 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 with, the frequency control word is forcibly switched to the frequency hopping frequency band corresponding to the frequency control word agreed in advance and not interfered with; the time of forced switching of the frequency control word is determined by the TOD time reference in the interference control information;

[0018] The second de-hopping module uses the de-hopping local oscillator generated after the frequency control word is switched to perform a de-hopping operation on the input frequency hopping signal to generate an intermediate frequency fixed frequency signal for subsequent demodulation and decoding.

[0019] Further, the interference detection unit 2 includes a down-conversion filtering module, a power statistics module and an interference judgment and framing module;

[0020] The down-conversion filter module converts the input intermediate frequency fixed frequency signals M1(n), M2(n), ...M N (n) are down-converted to zero frequency in sequence, and then low-pass filtered to obtain baseband bandwidth signals S1(n), S2(n), ..., S N (n);

[0021] The power statistics module counts the average power of the baseband bandwidth signal in turn. 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, the average power calculation is not performed; when the two are not equal, the average power of each baseband bandwidth signal is calculated according to the following formula

[0022]

[0023] In the above formula, each hop contains K data, I and Q are the in-phase component and orthogonal component of the baseband data respectively, i = 1, 2, ..., N;

[0024] During the frequency sweep process, the average power of each baseband bandwidth signal is calculated multiple times. The interference judgment and framing module compares the multiple average powers of each baseband bandwidth signal with the interference threshold power P. th When more than 80% of the average power is greater than the interference threshold power P th When the interference is detected, the baseband bandwidth signal of this segment is marked as 1, indicating that the baseband bandwidth signal of this segment is interfered with; otherwise, it is marked as 0, indicating that the baseband bandwidth signal of this segment is not interfered with. The marks of N segments of baseband bandwidth signals constitute N bits of marking information; in addition, the interference judgment and framing module receives the current TOD time reference, adds a fixed value to the current TOD time reference, and uses it as the interference avoidance TOD time reference information when the interference avoidance takes effect, and the size of the fixed value is the sum of the satellite-to-ground transmission delay and the signal processing delay; then, the interference avoidance TOD time reference information and the N-bit marking information form a format frame, and 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 via the satellite-borne modulator.

[0025] Compared with the background technology, the present invention has the following advantages:

[0026] 1. The present invention does not require additional interference detection and processing equipment, thus reducing system complexity and cost.

[0027] 2. The present invention does not use complex interference detection and suppression algorithms, the algorithm processing is simple, does not require higher-level protocol support, and occupies less resources.

[0028] 3. The present invention can effectively combat various interference patterns such as single-tone, multi-tone, comb-shaped and partial frequency bands whose center frequencies remain unchanged or change slowly within a certain period of time by changing the frequency hopping frequency points in coordination between the satellite and the ground.

[0029] In summary, the present invention has the advantages of simple algorithm implementation, small resource occupation, etc., and is particularly suitable for frequency hopping anti-interference communication in satellite communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a block diagram of the unit composition of the present invention.

[0031] Figure 2 It is a flowchart of satellite-ground coordination to avoid interference. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] Reference Figure 1 A satellite-ground coordinated interference detection and avoidance system includes a frequency scanning control unit 1, an interference detection unit 2, a frequency hopping control unit 3 and a ground terminal 4.

[0034] The frequency sweep control unit 1 performs a de-hopping operation on the input frequency hopping signal to de-hop the frequency hopping signal to an intermediate frequency fixed frequency signal. The specific implementation method is as follows: the segmented frequency sweep control module divides the frequency hopping bandwidth into N segments, N=2 m (m>1). Every Th (Th is the duration of a hop), the segmented frequency sweep control module generates the center frequency control word for each bandwidth in turn. The frequency hopping local oscillator generation module generates the local oscillator signal required for de-hopping according to the frequency control word transmitted by the segmented frequency sweep control module. The first de-hopping module de-hops the input frequency hopping signal according to the local oscillator signal generated by the de-hopping local oscillator generation module, and generates intermediate frequency fixed frequency signals M1(n), M2(n), ...M in turn. N (n), a total of N segments.

[0035] The down-conversion filter module in the interference detection unit 2 down-converts the intermediate frequency fixed frequency signal to zero frequency, and performs a low-pass filtering operation to obtain baseband bandwidth signals S1(n), S2(n), ..., S N (n) The power statistics module in the interference detection unit 2 performs power statistics on each baseband bandwidth signal S i (n) Perform multiple power calculations and compare the power calculation results with the set interference threshold power P thCompare and determine whether the spectrum is interfered according to the results of multiple comparisons. 1 indicates interference, 0 indicates no interference, and the marks of N baseband bandwidth signals constitute an N-bit interference detection result. The interference judgment and framing module adds a fixed value to the current TOD (Time of Date) and the interference detection result to generate interference control information, which is transmitted to the ground terminal 4 through the satellite modulator and directly to the frequency hopping control unit 3.

[0036] Reference Figure 2 The frequency hopping control unit 3 and the ground terminal 4 respectively decide whether to perform interference avoidance and switch to the non-interferenced frequency band in the same way according to the interference control information and the current TOD. The frequency hopping control unit 3 implements the frequency control word switching and de-hops the frequency hopping signal after the interference avoidance operation to the intermediate frequency fixed frequency signal for subsequent demodulation and decoding.

[0037] The brief working principle of this system is as follows:

[0038] The frequency sweep control unit 1 divides the frequency hopping bandwidth into N segments, and de-hops one of the bandwidths to the intermediate frequency fixed frequency in turn for each hop. The interference detection unit 2 down-converts each intermediate frequency bandwidth signal to the baseband, and performs multiple average power calculations and interference detection judgments. According to the results of multiple interference detection judgments, N bits are used to represent the interference information of each segment in the entire frequency hopping bandwidth. The current TOD value plus a fixed value is used as the starting time for satellite-to-ground interference avoidance, and the interference control information is generated in combination with the interference information and transmitted to the frequency hopping control unit 3 of the satellite-borne demodulator, and the interference control information is transmitted to the ground terminal through the 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 switch the interfered frequency point to the uninterfered frequency band according to the interference control information. The switching time is determined by the TOD in the interference control information, thereby achieving simultaneous change of the frequency hopping frequency point between the satellite and the ground to avoid interference.

[0039] In summary, the present invention performs segmented frequency sweeping on the frequency hopping bandwidth, detects the interference situation of each segment, and generates interference control information; the interference control information is transmitted to the ground terminal through the satellite-borne modulator one way and directly to the frequency hopping control unit the other way; the frequency hopping control unit and the ground terminal implement satellite-ground synchronization to change the frequency hopping pattern according to the interference control information to avoid interference. The invention is particularly suitable for situations in which there are partial frequency bands, single-tone, multi-tone, and comb-shaped interferences in satellite communication links whose frequencies remain unchanged or change slowly over a certain period of time. The protocol and implementation method of the invention are simple, occupy less resources, and can effectively solve the various interference patterns existing in satellite communication systems to achieve an anti-interference effect.

Claims

1. A satellite-ground coordinated interference detection and avoidance system, characterized in that: It comprises a frequency scanning control unit (1), an interference detection unit (2), a frequency hopping control unit (3), and a ground terminal (4), wherein: The frequency sweep control unit (1) is used to perform a de-hopping operation on the input frequency hopping signal, and de-hop the frequency hopping signal to an intermediate frequency fixed frequency signal; The interference detection unit (2) is used to down-convert the intermediate frequency fixed frequency signal to the baseband, and perform a low-pass filtering operation to divide the frequency hopping bandwidth into baseband bandwidth signals S1(n), S2(n), ..., S N (n); used for each baseband bandwidth signal S i (n) Perform power calculation, i = 1, 2, ..., N, and compare the power calculation result with the set interference threshold power P th Comparison is performed to determine whether the spectrum segment is interfered with; it is also used to add a fixed value to the current TOD time reference and the interference detection result to generate interference control information, and the interference control information is divided into two paths, one of which is transmitted to the ground terminal (4) through the satellite modulator, and the other is transmitted to the frequency hopping control unit (3); The frequency hopping control unit (3) determines whether to perform an interference avoidance operation according to the interference control information and the current TOD time reference, and de-hops the frequency hopping signal after the interference avoidance operation 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 achieving satellite-ground synchronization to change the frequency hopping pattern and avoid interference with the frequency hopping bandwidth; The frequency sweep control unit (1) is composed of a segmented frequency sweep control module, a first de-hopping local oscillator generation module and a first de-hopping module; The segmented frequency sweep control module divides the frequency hopping bandwidth into N segments, N = 2 m , m>1, every hop duration Th, the segmented frequency sweep control module generates the center frequency control word of each bandwidth in turn; The first de-hopping local oscillator generating module generates the local oscillator signal required for de-hopping according to the frequency control word 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 generates intermediate frequency fixed frequency signals M1(n), M2(n), ...M N (n); The frequency hopping control unit (3) is composed of an interference avoidance control module, a frequency hopping pattern mapping module, a second de-hopping local oscillator generation module and a second de-hopping module; The interference avoidance control module determines which segments in the frequency hopping bandwidth are interfered with based on the received interference control information, and controls the switching of the frequency hopping local oscillator to avoid interference; The frequency hopping pattern mapping module generates a frequency control word according to the current TOD time reference information; The second de-hopping 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 with, the frequency control word is forcibly switched to the frequency hopping frequency band corresponding to the frequency control word agreed in advance and not interfered with; the time of forced switching of the frequency control word is determined by the TOD time reference in the interference control information; The second de-hopping module uses the de-hopping local oscillator generated after the frequency control word is switched to perform a de-hopping operation on the input frequency hopping signal to generate an intermediate frequency fixed frequency signal for subsequent demodulation and decoding; The interference detection unit (2) comprises a down-conversion filtering module, a power statistics module and an interference judgment and framing module; The down-conversion filter module converts the input intermediate frequency fixed frequency signals M1(n), M2(n), ...M N (n) are down-converted to zero frequency in turn, and then low-pass filtered to obtain baseband bandwidth signals S1(n), S2(n), ..., S N (n); The power statistics module counts the average power of the baseband bandwidth signal in sequence. 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), the average power calculation is not performed; when the two are not equal, the average power of each baseband bandwidth signal is calculated according to the following formula In the above formula, each hop contains K data, I and Q are the in-phase component and orthogonal component of the baseband data respectively, i = 1, 2, ..., N; During the frequency sweep process, the average power of each baseband bandwidth signal is calculated multiple times. The interference judgment and framing module compares the multiple average powers of each baseband bandwidth signal with the interference threshold power P. th When more than 80% of the average power is greater than the interference threshold power P th When the interference is detected, the baseband bandwidth signal of this segment is marked as 1, indicating that the baseband bandwidth signal of this segment is interfered with; otherwise, it is marked as 0, indicating that the baseband bandwidth signal of this segment is not interfered with. The marks of the N segments of baseband bandwidth signals constitute N bits of marking information. In addition, the interference judgment and framing module receives the current TOD time reference, adds a fixed value to the current TOD time reference, and uses it as the interference avoidance TOD time reference information when the interference avoidance takes effect. The size of the fixed value is the sum of the satellite-to-ground transmission delay and the signal processing delay. Then, the interference avoidance TOD time reference information and the N bits of marking information are combined into a format frame, and the format frame is divided into two paths, one of which is transmitted to the frequency hopping control unit (3), and the other is transmitted to the ground terminal (4) via the satellite-borne modulator.

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