Research And Implementation On HF Technology In Strong Single-frequency-interference Under The Condition Of Extremely Low SNR

Techniques of the strong single-frequency-interfere in extremely Low SNR short-wave can offer special anti-single wave interfere technique in condition of bad electromagnetism, finite frequency band and incapable of spread-spectrum technique, to make sure the short-wave can transmit an emergency communication. In view of the fixed and time-variant frequency interferences, this article offers various restraining single-frequency-interfere arithmetic from two angles of the frequency domain and time domain.First of all, starting with the estimate of signal parameter (e.g. amplitude, frequency and phasic), it makes a research in algorithms of direct, subdivide the spectrum, high-precision FFT and so on. And then it puts forward removing method based on frequency domain, trapping method based on frequency domain and removing method based on time domain etc. to restrain strong single sine wave interfere from the angle of the frequency domain and time domain and makes qualitative and quantitative analysis towards the various arithmetic. Considering the opponent's"cunning"and influence of signal trace, it studies the RLS(recursive of least square)algorithm to track the frequency, and designs the self-adaptive notch filter changed to frequency interfere when trapping. At last, it takes steady trapping method based on frequency domain in to practice on DSP hardware platform.