Interference Suppression Method Combined Subspace Projection and Clean

Abstract

An interference suppression method that combines subspace projection and CLEAN, converts the radio frequency signal from the array antenna into an analog baseband signal, converts it into a digital baseband signal in turn, calculates the interference orthogonal complement space of the digital baseband signal, and projects the digital baseband signal to Interfering with the orthogonal complement space, estimating the Doppler frequency offset, using the symmetrical characteristics of the OFDM signal cyclic prefix in the digital baseband signal to estimate the direction of the OFDM direct path signal through the CLEAN algorithm, and extracting the normal Cross-frequency division multiplexing direct path signal, removing cyclic prefix after Doppler frequency offset compensation, converting to frequency domain signal through FFT operation, completing sampling frequency conversion through 4 times frequency domain downsampling, and estimating through frequency domain least squares Value and linear interpolation method to complete channel estimation, complete channel equalization through zero-forcing equalizer, and obtain estimated value of transmitted bit sequence through demodulator, deinterleaver and channel decoder. The invention can effectively overcome the interference of range finder pulse and scattered multipath signals.

Description

technical field [0001] The present invention relates to an interference suppression method. In particular, it relates to an interference suppression method combining subspace projection and CLEAN. Background technique [0002] In order to ensure the safe, reliable and efficient operation of the new-generation air traffic management system of civil aviation, the International Civil Aviation Organization (ICAO) has proposed two candidate technical solutions for ground-air data link: L-band Digital Aviation Communication System 1 (L-DACS1) and L-band Digital Aviation Communication System 2 (L-DACS2). Compared with the L-DACS2 system, the L-DACS1 system has the characteristics of higher spectral efficiency, higher transmission capacity, and more suitable for frequency selective fading channel transmission. Therefore, the L-DACS1 system has received extensive attention from the civil aviation community. At the same time, in order to solve the problem of lack of frequency resour...

AI Technical Summary

Problems solved by technology

In practical application, this method has the following two problems: the position where the pulse interference signal appears is not easy to determine, and the ICI interference is caused after the pulse is extinguished

There are also two problems in the pulse clipping method: the pulse clipping value is not easy to determine, and the signal still has pulse interference after pulse clipping

However, in the L-band digital aviation communication system 1 (L-DACS1), the pulse interference generated by the range finder is strongly correlated pulse interference, so the compressive sensing method is difficult to be directly applied to the pulse interference suppression of the OFDM system range finder

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