Development of Acquisition Module for a Software Based IRNSS Receiver

Indian Regional Navigational Satellite System (IRNSS) consists of two major modules in the receiver operation, namely, acquisition and tracking. Based on the study of Global Positioning System (GPS) receiver operations IRNSS is being implemented. But IRNSS uses Binary Offset Carrier (BOC) modulation technique to generate the transmitting signal. This paper deals with the implementation of acquisition module for IRNSS. Acquisition is a process to find code shift in Pseudo Random Noise (PRN) code and Doppler shift in carrier frequency of received IRNSS signal. Software Defined Receiver (SDR) technology is used to implement acquisition. SDR technology helps in designing a flexible open-Architecture receiver. Proposed method uses Fast Fourier Transform (FFT) to implement correlation of received signal and locally generated carrier signal in acquisition process. Proposed method is implemented on one millisecond period Intermediate Frequency (IF) IRNSS signal sampled at 50MHZ.This paper also compared the acquisition of GPS and IRNSS signals.