Design And Implementation Of Short-Wave Anti – Jamming Transmission System

The shortwave anti-jamming data communication refers to the strong interference channel conditions, in the conventional communication system can not realize the situation of information transmission, information transmission with very low to ensure the communication link of a data communication mode. HF anti-jamming data communication can effectively overcome the extremely low signal-to-noise ratio, strong narrowband interference and multipath can achieve greater, "not bad, disturbed continuously", has an important significance in military communication and civil field.This topic is the performance of physical layer waveforms on the third generation HF communication system based on the background of the upgrade. In the communication environment is bad, real-time and accurate data transmission demand of short wave communication as much as possible. Studied on HF anti-jamming transmission system, the main research contents are the following:1, Combining with engineering practice, a number of anti interference design in this paper with using direct sequence spread spectrum method, expect to achieve a signal-to-noise ratio of-20 dB, low rate information transmission is greater than the harsh conditions under multipath dozen milliseconds, to ensure that the failure to 75~2400bps and other conventional data transmission technology to achieve a small case, effective normal communication.2, The shortwave anti-jamming data communication, signal acquisition is the key technical problems in the process of receiving data, the anti-interference performance has a direct impact on the performance of the whole system, in the design must take full account of the very low signal to noise ratio, the impact on system performance of detection probability and false alarm rate of short burst signals. Combining the engineering practice, puts forward a kind of acquisition algorithm based on frequency domain signal packet short PN, and a detailed analysis of the performance of the proposed algorithm.3, This paper proposes a nonlinear interference suppression algorithm for multi loop of the algorithm in order to reduce narrowband interference suppression caused by the pseudo code signal distortion, the non-linear decision feedback circuit, decision feedback system using estimates of the pseudo code spread spectrum code sequence or CHIP to derive the value estimate of the disturbance signal, reduce the noise suppression. Then the estimate value as a reference input to the adaptive filter. Because the spread spectrum code reference signal and the original signal correlation decreases, the decision feedback can better suppress interference and reduce the distortion of spread spectrum signal, effectively improves the anti-interference ability.4, After the completion of the key technology of software simulation of anti jamming waveform, design of HF digital processing platform for anti jamming waveform to TMS320C5509 as the core, has completed the hardware design, frequency down conversion design and automatic gain design, then gives the software implementation of the process. And the index test is performed on a channel simulator, the measured results verify the feasibility and validity of the design method.