Implementation of Multichannel GPS Receiver Baseband Modules

摘要

Global Positioning Systems are mainly used for finding the location of an object across the globe. GPS receivers can be implemented by using software defined radio techniques. In this paper, hardware implementation of base band (acquisition and tracking) modules of a GPS receiver using system generator 9.2 has been carried out. The implementation will be tested on Lyrtech (small form factor-software defined radio) platform which consists of 3 layers. The upper layer being the radio frequency (ISM band receiver) layer, middle layer is the ADACMasterⅢ layer and the last is digital processing (DSP) layer. The data transfer between the FPGA Virtex4 SX35 and DSP module is done using a TMS320DM6446 Davinci processor. Generation of 17MHz Intermediate frequency from the RF signal received by the GPS receiver has been achieved. Currently the process of building the base band modules of acquisition and tracking are in progress. Acquisition is being implemented using parallel code phase search algorithm. This is performed by using FFT. Tracking module is implemented by using Costas loop and Delay Lock Loop (DLL). First the base band modules are being made in simulink and simulation results will be tested. Once this is achieved, real time hardware implementation will be done. The results will lead to the development of indigenous GPS receivers with single and multiple channels within the same hardware with reconfiguration. Also it is adaptive for consistent receiving and tracking of the signals.