Narrowband Interference Suppression Algorithm In Leo Satellite Spread Spectrum Communication Research

The Master Dissertation was written with the subject 'Narrow-BandInterference Suppression in the Low Orbit Satellite SS Communication'and the tasks I had accomplished. Micro-satellite technology is a pop technology nowadays and it has agood Application outlook in communication, remote sensing, scienceresearch, technique demonstration, interstellar exploration, education, andso on. Low orbit satellite communication that mainly operates with shortdata was demanded in national defense and civil market. But it is not wellapplied in China because the complicated radio environment. It is one of the key techniques in low orbit satellite communicationsystem to suppress the interference falling in the same frequency band andthe jamming with some effective measures. This technique is significant inboth theory and application. There is a special anti-jamming module in theMilstar system. In this Dissertation some narrow band interference suppressionAlgorithms in the low orbit satellite SS communication was studied andsimulated. Narrow band interference's bandwidth is much narrower thanthe SS signal. It includes monotone interference, polyphony interferenceCW pulse interference, narrow band Gaussian noise and some other narrowband signals. In the process of study, we did some base-band simulation on theBPSK signal contaminated by narrow band interference. The interferencesignals we use in this process are mainly polyphony signal that has somefixed frequencies and chirp signal whose frequency is sweeping all the time.The chirp signal represents a class of no-stationary interference. We simulated and discuss the interference suppression filter in timedomain and frequency domain respectively. The filtering algorithms intime domain includes LMS based transversal linear adaptive filter,nonlinear adaptive filter, the linear adaptive filter with Lattice structure ,the nonlinear Adaptive structure with Lattice structure and so on. Thefiltering algorithms in the frequency domain includes TZ(thresholdZeroize), TC(threshold Clipping), CMF(Condition Median Filter) and so IIIon. In the FFT and IFFT transform process we used some signal processingmeasure such as windowing and Lapped processing. We compared anddiscussed the performance of these algorithms according to the SNRimprovement. We also make some alteration on some algorithms in the simulationprocess and make it has better performance in narrow-band interferencesuppression and get more improvement on SNR. A whole chapter was written to introduce the interference suppressiontechniques based on filter bank and time-frequency distribution. We didsome simulation and make some conclusions. In the end, According to the signal flow in the simulation process andour investigation we presented a hardware scheme based on theTMS320C6701 chip of TI. We make some argumentation on the resourcevalidity and written some simple core program.