Research On Spread Spectrum Ranging System And The Digital Implementation

Spread spectrum ranging finish the detection and location of the target under testby measuring the arrival angle or distance to the base station and the target to bemeasured.Spread spectrum ranging system has advantages of beam-width,high measureprecision, long Measure distance, Strong real-time and.can work around the clock.Andspread spectrum ranging overcomes the weakness of traditional distance measurementmethod, and achieves the function of information communication, obtaines a very goodapplication and development.The multi-target spread spectrum ranging system is studied deeply and anall-digital system is realized with FPGA in this thesis. The main contents are as follows:Firstly, the spread spectrum communication technology and the basic principle ofspread spectrum ranging were discussed; present a whole simulation figure of thespread spectrum ranging system; the syestem was simulated and the performance wasanalyzed; and the feasibility of the designed system was verified.Secondly, the paper introduced the generation of MAI and analyzed the effect ofMAI in the probability of detection and false alarm probability of the spread spectrumranging system and near-far effect in the multi-targets spread spectrum ranging. It alsointroduced a variety of MUD techniques, simply analyzed the advantages anddisadvantages of them and chose the parallel interference cancellation detector (PIC) asthe realization of the algorithm, which is simple and superior of performance. Then thepaper focused on the improvement of the PIC in the detection probability and falsealarm probability of spread spectrum ranging system, and the performance ofanti-near-far affect. The system simulation platform of the multi-targets spread spectrumranging modem in MATLAB was built and simulation waveforms were given.Finally, various modules of the multi-targets spread spectrum ranging system weredesigned, simulated and implemented in QuartusII environment, including the keymodules such as spread spectrum code generator, raised cosine filter, digital upwardfrequency conversion (DUC), digital down conversion (DDC), Cascaded integratorcomb filter(CIC), digital matched filter (DMF) and so on, whose simulation waveformswere given. Then the hardware circuit was designed with Protel99, and the program wasdownloaded to the board, the waveform can be observed using the oscilloscope. Theranging waveforms showed that the design of spread spectrum ranging system in this paper completely met the design requirements and achieved the purpose of ranging.