Kalman Filter-based Short-wave-continuous Wave Noise Reduction Technology

In this paper, the short-wave morse telegraph signal noise reduction technology is discussed. In the wireless communication system, noise interference is the main effect of communication. Because short-wave morse telegraph communication belongs to the analog communication standard, it depends on the sky wave ionospheric reflection and ground wave transmission, as well as the channel. With the development of industrial electrification, the interference the short-wave channel suffers is growing, the quality of the transmission of morse signal has a sharp deterioration. It leds to declining levels of radio duty collecting, it makes it very difficult for the operator to listen to the morse telegraph telegraph signals. The purpose of this paper is to use the digital signal processing technology to build a online signal processing module to be after-level of the radio audio processing system, on the basis of no alteration of the original radio equipment hardware. After denoising of morse audio signal out from radio, it can raise the SNR of the morse audio signal, improve the listening sense of the morse audio signal, on the basis of reducing the labor intensity of radio wireless telegraphy service operator, improve the accuracy of collecting duty, and enhance the business level of professional skill.Based on the previous studies, this paper first analyze the dot-and-dash of morse and the rules and the correlation between characters, it also study the effects of type of noise of morse signal, discuss the pollution mode of the morse signal, analyze the influence of the noise of short-wave communication which the erection methods of equipment makes, it studys the principle of artificial collecting of noise can achieve by collecting telegraph officers in noise state. According to signal autocorrelation of morse code, it analyzes the signal processing of human brain in memory and recognition of morse telegraphy. It studys ways to deal with anti-noise of collecting staff with a uneven way in transmitter mode. It analyzes the existing noise reduction technology in morse signal, establish a short space state model of morse telegraph. It uses kalman filter algorithm to conduct the derivation, and kalman filter model was established.it investigates the audio filter method of kallman filtering in short-wave morse telegraphy signal and writes the DSP code in CCS environment, with the combine of existing audio output interface in duty stations, it builds a digital signal denoiseprocessing module with the core of DSP5402 and AIC23, uses the AIC23 to do the AD sampling of audio signals out from the radio, and use the kalman filter algorithm to conduct the denoising of morse audio signal in DSP5402, after processing, the audio signal output to the radio operator for collecting through the AIC23 headphone.In order to verify the performance of the noise reduction of kalman filter to the morse audio signal, we simulated an audio signal morse white a gaussian noise, use the method of calculation of the output SNR to take a contrast experiment of kalman filter and the traditional narrow-band filter. The results show that it is estimation model which kalman filter algorithm make for system parameters and noise statistics decides the performance of kalman filter can achieve in noise reduction of morse signal. When SNR of morse signal is larger, kalman filter is fully able to meet the noise reduction effect of narrow-band filter...