Implementation of DPSK demodulation using quadrants method in FPGA for IFF MKXII digital receiver

Abstract

This paper presents a technique for demodulating the DPSK (Differential Phase Shift Keying) signal in digital Receivers. This technique is in contrast to the conventional delay and comparison method as it uses quadrants information for DPSK demodulation with optimum delay and less no. of FPGA (Field Programmable Gate Arrays) resources. The scope of this paper is to demodulate the DPSK Signal for Civil Mode `S' IFF (Identification of Friend or Foe) MKXII System. This method can be implemented easily in hardware with good performance. It is based on CORDIC (Coordinate Rotation Digital Computer) algorithm. In this the quadrants are selected based on I and Q data generated from ADC samples. From the quadrants Phase difference will be found. Based on the phase difference DPSK data shall be decoded to retrieve the information.