The Simulation And Study Of PN-Code Ranging Technology

With the rapid development of integrated circuit technology, microelectronics technology and digital signal processing technology, the spread-spectrum communication technology because of its strong anti-jamming capability, good confidentiality and high precision ranging, has been widely used in the mobile communication, global positioning, space communication, long range detection and some other fields. And as the result of the auto-correlation, cross-correlation and long periodicity, pseudo random code plays a very important role in spread-spectrum communication system, therefore, PN-code ranging technology is becoming more and more hot now. PN-code ranging technology can well balance both of distance and precision, and it can even achieve multiple measurements and controls at the mean time by integrating code division multiple access technology. Since the PN-code ranging technology has so many strengths in global ranging field, this paper studies the PN-code ranging’s application in global positioning system theoretically and practically.This thesis talks about the modules of carrier separation, PN-code acquisition and tracking process in more details as those are the key sectors to realize PN-code ranging telenology, and it introduces the validation method for the system as well. In the transmitting terminal, it optimizes the modulation process by combining the modulation and the signal generator, and introduces the generation of the PN-Code in detail. In the PN-Code acquisition portion of the receiving terminal, it explains and compares the different methods of acquisition, and introduces how to realize the demodulation and the correlation module; and during PN-Code tracking step, it explaines the realization of the local long PN-Code module and the phase demodulation module, and it uses the sampling method to achieve the real time shift of the local long PN-Code. As for the simulation portion, base on the ModelSim platform, it uses Verilog language to pre-simulate the generation of the PN-Code, the modulation step, the PN-code acquisition step and the PN-code tracking step, so as to verify the data to ensure the design is correct.The design of the PN-Code ranging system has further improved the precision of the PN-code ranging system, and it is more convenient to be implemented, so it does not only offer the technical basis for the realization of the conventional ranging system, but also provides the help for emerging market such as personal positioning system, indoor positioning, etc.