Shaping Filter The Bars Expansion Signal Carrier Frequency And Code Rate Is Estimated

The spread spectrum communications are widely used in modern military communications, satellite communications, mobile communications and command, control, communication and intelligence( C~3I ) systems, because of its well multi-address access, low probability of interception, excellent performance of anti-jamming and secrecy. We need to detect this kind of non-cooperative weak communication signals and estimate its parameters to obtain the Pseudorandom(PN) sequence as the final goal in reconnaissance. The shaping-filter, which is usually used in communication has some affect on the waveform of the signal, so the traditional techniques on detection and estimation are often incapable and find some new approaches are the main work of the dissertation.Based on DS-SS technology, the DS-SS communication system's operating principle and its performance are studied, the DS-SS communication system under shaping-filter situation is modeled and simulated. The simulation program and the mathematical model of the DS-SS communication system are designed. The Inter-Symbol Interference(ISI), some kinds of shaping-filter technologies are introduced and the performance of raised cosine roll-off filter and the square-root raised cosine roll-off filter are compared.Based on the performance analysis of the general approaches on carrier frequency and symbol-rate detection and estimation, the performance influence of the DS-SS signal's carrier frequency and symbol-rate detection and estimation using Square-Device and Pre-filter-Delay-and-Multiply Device under the square-root raised cosine roll-off filter is profoundly studied. From deduction, the mean and the variance of the probability distribution of the filtered signal are derived. And the detection probability, the false-alarm probability, and the influence coefficient of the shaping-filter in the DS-SS signal symbol-rate detection are given. Then we do some computer simulation, the result verifies the validity of the theoretical results.Combined with the analysis of the shaping-filter, we use the triple correlation overlapping sampling method in IR system to recover the DS-SS signal and a method...