A receiving device for resisting narrowband interference in direct sequence spread spectrum communication system

Abstract

The present invention discloses a narrowband interference-resistant receiving device in a direct sequence spread spectrum communication system, belonging to the field of digital signal processing. The device comprises a DC module, an orthogonal downconverter, a decimation module, a low-pass filter module, a digital AGC module, an interference trap module, a sampling rate conversion module, a frequency estimation module, a parameter mapping module, and a table lookup module. The present invention implements interference trapping by combining sampling rate conversion with a table lookup, offering advantages such as simple processing, low resource usage, and high trapping accuracy. The device has a wide range of applications and can also be used in spaceborne equipment with limited hardware resources and stringent performance requirements.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a receiving device capable of resisting narrowband interference in a direct sequence spread spectrum communication system. Background Art

[0002] In direct sequence spread spectrum communication systems, since the communication signal undergoes direct sequence spread spectrum, the signal bandwidth is widened, making narrowband interference more likely to fall within the signal bandwidth, causing serious interference to the receiver. The conventional approach is to filter out narrowband interference using frequency or time domain filters.

[0003] The key to designing time-domain or frequency-domain anti-narrowband filters lies in accurately calculating the frequency of the interfering signal. Due to resource limitations, conventional receivers typically sample at rates four or eight times that of the signal being processed. This results in low resolution after the FFT calculation. Increasing the number of FFT points increases hardware resource usage and the computational effort exponentially. Summary of the Invention

[0004] The object of the present invention is to avoid the deficiencies in the above-mentioned background technology and provide a receiving device for resisting narrowband interference in a direct sequence spread spectrum communication system, which occupies low resources, has high calculation accuracy, low noise and wide applicability.

[0005] The technical solution adopted in the present invention is:

[0006] A receiving device for resisting narrowband interference in a direct sequence spread spectrum communication system includes a DC removal module 1, an orthogonal down-converter 2, an extraction module 3, a low-pass filter module 4, a digital AGC module 5, an interference notch module 6, a sampling rate conversion module 7, a frequency estimation module 8, a parameter mapping module 9 and a table lookup module 10; wherein,

[0007] The DC removal module 1 obtains the DC component by statistically sampling the signal, removes the DC component from the signal, obtains the DC-removed signal, and outputs it to the orthogonal down-converter 2;

[0008] The orthogonal down-converter 2 performs orthogonal down-conversion on the DC-removed signal to obtain a baseband signal, and outputs the baseband signal to the extraction module 3;

[0009] The extraction module 3 performs multiple extraction on the baseband signal to obtain the expected 4-times or 8-times sampled extraction signal, and outputs the extraction signal to the low-pass filter module 4;

[0010] The low-pass filtering module 4 performs low-pass filtering on the extracted signal to obtain a low-pass filtered filtered signal, and outputs the filtered signal to the digital AGC module 5 and the sampling rate conversion module 7 respectively;

[0011] The digital AGC module 5 adjusts the amplitude of the filtered signal and outputs it to the interference trap module 6;

[0012] The interference notch module 6 performs interference filtering on the amplitude-adjusted filtered signal according to the filter parameters input by the table lookup module 10, thereby completing the interference notch operation;

[0013] The sampling rate conversion module 7 performs sampling rate conversion on the filtered signal and outputs the converted signal to the frequency estimation module 8;

[0014] The frequency estimation module 8 performs Fourier transform on the signal after sampling rate conversion, finds the frequency point where the narrowband interference is located, obtains the frequency control word corresponding to the interference frequency point, and outputs the frequency control word to the parameter mapping module 9;

[0015] The parameter mapping module 9 modifies and maps the frequency control word to obtain address information used to search the filter parameter table, and outputs the address information to the table lookup module 10;

[0016] The table lookup module 10 outputs corresponding filter parameters according to the input address information, and outputs the filter parameters to the interference trap module 6 .

[0017] Compared with the background technology, the present invention has the following advantages:

[0018] 1. The present invention adopts the method of interference detection and table lookup output filter coefficient to reduce hardware resource occupation and meet the demand of low resource occupation of satellite-borne equipment.

[0019] 2. The sampling rate conversion concept in the present invention enables the signal receiving branch to operate at a high sampling rate and the interference detection branch to operate at a variable sampling rate, which can achieve high-precision positioning of the interference position, obtain more accurate interference frequency control words, and achieve better notch effect.

[0020] 3. The present invention can be implemented through FPGA, a large-scale field programmable device, and has the advantages of simple circuits, small size, low cost, stable and reliable performance, and is suitable for engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an electrical schematic diagram of the interference trapping method in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Reference Figure 1A receiving device for resisting narrowband interference in a direct sequence spread spectrum communication system includes a DC removal module 1, an orthogonal down-converter 2, an extraction module 3, a low-pass filtering module 4, a digital AGC module 5, an interference notch module 6, a sampling rate conversion module 7, a frequency estimation module 8, a parameter mapping module 9 and a lookup table module 10.

[0024] The function of the DC removal module 1 is to obtain the DC component by statistically sampling the signal, and then remove the DC component from the signal to obtain the DC-removed signal; the function of the orthogonal down-converter 2 is to perform orthogonal down-conversion on the DC-removed signal to obtain the baseband signal; the function of the extraction module 3 is to perform multiple extraction on the baseband signal to obtain the expected 4-fold or 8-fold sampling extraction signal; the function of the low-pass filter module 4 is to perform low-pass filtering on the extraction signal to obtain the filtered signal after low-pass filtering; the function of the digital AGC module 5 is to complete the amplitude adjustment of the filtered signal to ensure the stability of the output signal amplitude; the function of the interference notch module 6 is to adjust the filter signal according to the filter input by the lookup table module. The filter parameters are used to filter out interference on the filtered signal after amplitude adjustment, complete the interference notch operation, and be used for subsequent capture, demodulation, etc.; the function of the sampling rate conversion module 7 is to complete the sampling rate conversion of the signal after low-pass filtering; the function of the frequency estimation module 8 is to complete the Fourier transform of the signal after sampling rate conversion, find the frequency point where the narrowband interference is located, and obtain the frequency control word corresponding to the interference frequency point; the function of the parameter mapping module 9 is to correct and map the frequency control word to obtain the address information used to search the filter parameter table; the function of the table lookup module 10 is to output the corresponding filter parameters through the input address information for the interference notch module 6.

[0025] The brief working principle of the present invention is as follows:

[0026] The DC removal module removes the DC component of the sampled signal to obtain the DC-removed signal; the orthogonal down-converter performs orthogonal down-conversion on the DC-removed signal to obtain a baseband signal; the extraction module extracts the baseband signal by multiples to obtain the expected 4-fold or 8-fold sampled extraction signal; the low-pass filtering module performs low-pass filtering on the extracted signal to obtain a filtered signal after low-pass filtering; the digital AGC module adjusts the amplitude of the filtered signal to ensure the stability of the output signal amplitude; the interference notch module filters the signal according to the filter coefficient input by the lookup module to complete the interference notch operation; the sampling rate conversion module converts the sampling rate of the low-pass filtered signal; the frequency estimation module performs Fourier transform on the sampling rate converted signal to find the frequency point where the narrowband interference is located and obtain the frequency control word corresponding to the interference frequency point; the parameter mapping module corrects and maps the frequency control word to obtain the address information used to search the filter parameter table; the lookup module outputs the corresponding filter parameters through the input address information for the interference notch module.

[0027] The present invention can be implemented based on FPGA and can also be used for satellite-borne equipment with limited hardware resources and strict performance requirements.

[0028] In summary, the present invention realizes interference notching by changing the sampling rate and combining table lookup, which has the advantages of simple processing, low resource occupation, and high notching accuracy. It has a wide range of applications and can also be used for satellite-borne equipment with limited hardware resources and strict performance requirements.

Claims

1. A receiving device for resisting narrowband interference in a direct sequence spread spectrum communication system, characterized in that: It includes a DC removal module (1), an orthogonal down-converter (2), an extraction module (3), a low-pass filter module (4), a digital AGC module (5), an interference trap module (6), a sampling rate conversion module (7), a frequency estimation module (8), a parameter mapping module (9) and a table lookup module (10); wherein, The DC removal module (1) obtains a DC component by statistically sampling the signal, removes the DC component from the signal, obtains a DC-removed signal, and outputs the signal to the orthogonal down-converter (2); The orthogonal down-converter (2) performs orthogonal down-conversion on the DC-removed signal to obtain a baseband signal, and outputs the baseband signal to the extraction module (3); The extraction module (3) extracts the baseband signal by multiples to obtain an expected 4-times or 8-times sampled extraction signal, and outputs the extraction signal to the low-pass filter module (4); The low-pass filtering module (4) performs low-pass filtering on the extracted signal to obtain a low-pass filtered filtered signal, and outputs the filtered signal to the digital AGC module (5) and the sampling rate conversion module (7) respectively; The digital AGC module (5) adjusts the amplitude of the filtered signal and outputs it to the interference trap module (6); The interference notch module (6) performs interference filtering on the amplitude-adjusted filtered signal according to the filter parameters input by the table lookup module (10), thereby completing the interference notch operation; The sampling rate conversion module (7) performs sampling rate conversion on the filtered signal and outputs the converted signal to the frequency estimation module (8); The frequency estimation module (8) performs Fourier transform on the signal after sampling rate conversion, finds the frequency point where the narrowband interference is located, obtains the frequency control word corresponding to the interference frequency point, and outputs the frequency control word to the parameter mapping module (9); The parameter mapping module (9) corrects and maps the frequency control word to obtain address information used for searching the filter parameter table, and outputs the address information to the table lookup module (10); The table lookup module (10) outputs corresponding filter parameters according to the input address information, and outputs the filter parameters to the interference trap module (6).

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