Key Technologies In The Loop "guided Link-based Television System," People

In the guidance link of man in the loop with video guidance system, after the camera carried by a missile got the real-time target image, the image was transmitted to control center through wireless up channel, then people selected the target in which they interest and sent the commands to guide the bomb to attack. For the giant multi-images and the limited wireless bandwidth, the common image coding techniques with high compression ratio made the images serious distortion, it affected people's judgments on suspected target. When this system was applied in the military environment, it was a problem to ensure the security of information transmission.In order to solve this problem, in this paper, a possible solution was proposed. Firstly, after in-depth study on traditional embedded coding in wavelet domain, by selecting Motion JPEG2000 image compression standard based on EBCOT and combining with the region of interest (ROI) coding, either the high compression ratio or the target image's clarity could be ensured. In this part, two wavelet filters, CDF9/7 and Le Gall 5/3 were realized by MATLAB simulation; discussed the bit-plane coding process and cut off bit stream in an optimization order in detail; a simulation on EZW and SPIHT algorithm was realized and compared with the JPEG2000 coding performance.Secondly, Spread spectrum technology was applied in communication system to assure security currently. As the phase shift keying (PSK) signal modulation and demodulation techniques better than the amplitude shift keying (ASK) and frequency shift keying (FSK) in both bandwidth efficiency and anti-interference, traditional direct sequence spread spectrum(DSSS) technology to use more two-phase shift keying (2PSK) signal modulation, and related technologies were more mature. In this paper, a minimum frequency shift keying (MSK) signal modulation DS signal was adopted, which could adapt to the nonlinear channel and improve the spectrum efficiency, and anti-interference ability stronger than 2PSK signal. A synchronous capture method of adaptation filter and related synchronous envelope tracking circle were applied to achieve synchronization of PN by receiver. Finally, two typical jammings, narrowband jamming and broadband blocking jamming, were designed and added into the system, and then the BER performance of the system was simulated.