Design of a carrier recovery by remodulation in QPSK

Abstract

This project aims at designing a carrier recovery circuit based on re-modulation to be used in QPSK demodulator. The circuit can be used in radio frequency range but more specifically the FM range {87MHz to 108MHz}. The idea is based on correcting phase of the received signal. In 1971, Caccianamum and wokjska tried to solve the problem. QPSK is better than BPSK since it is possible to transmit as twice as much information in the same bandwidth and noise relation as in BPSK. Re-modulation is a data aided process and therefore minimal errors occur at the receiver side. The design consists of multipliers, low pass filters, parallel to serial converter, delay, voltage control oscillator, 900 phase shifters and limiter.