QPSK Modulator Transmits Satcom Data

摘要

This unique modulator provides both spectral and power efficiency when transmitting unequal data rates from two different satellite payloads. Digital Modulation is often a means of transmitting payload data from orbiting satellites to ground stations. Such is the case for satellites in the Indian Remote Sensing (IRS) satellite system. In one such approach, quadrature phase-shift-keying (QPSK) modulation provides both spectral and power efficiency. In a QPSK modulator, two data streams simultaneously modulate a carrier signal. For optimum use of available satellite power, an unbalanced QPSK (UQPSK) modulator is often used. The design and simulation for such a modulator will be shown here, along with methods for demodulating such signals.