Design and Implementation of QPSK Modulator and Demodulator for Wireless Transceiver

• Main Authors: Chih-Chung Lee, 李致中
• Other Authors: Man-Long Her
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/46798976931841682439

碩士 === 逢甲大學 === 電子工程所 === 94 === Electromagnetic wave is commonly used as the media for wireless transmission at long distance. Electromagnetic wave is known as carrier wave and it will not be weakened even in airless environments. Using carrier wave to transmit signals is called modulation. Demodulation is the process of extracting signals from carrier wave. There are four methods in analog modulation, such as AM, FM, PM, etc. There are many techniques in the digital modulation include Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), and Phase Shift Keying (PSK) etc. The ASK technique is easily interfered and attenuated by electromagnetic wave. And electromagnetic wave has the ability to cause bit error rate (BER) to increase. Therefore, there are many technologies adopt FSK or PSK techniques to implement wanted modulation. The Quadrature Phase Shift Keying (QPSK) modulation is 2-bits technique which can transmitted a signal modulation symbol and to reduce symbol error rate. As we understand, QPSK is usually applied when signal is transmitted with high frequency interference noise, for instance, satellite transmission system. This thesis is set in four parts to discuss the design and implementation of QPSK modulator and demodulator for wireless transceiver.