Characterizations and Applications of Quadrature Signals

• Main Authors: Feng-Ju Wu, 吳鳳珠
• Other Authors: Jie-Cherng Liu
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/21327480455101987620

碩士 === 大同大學 === 通訊工程研究所 === 93 === Quadrature processing technique is the core technology of modern digital communication systems. The using of quadrature processing technique transforms the signal from real to complex domain, i.e., makes a two-dimensional signal to become a three-dimensional signal. That can enlarge the degree of freedom and flexibility on the processing of a signal, and thus many new techniques and fancy structures can be developed accordingly. The bandpass filtering using a prototype lowpass filter is obtained by using the principles of quadrature modulation and demodulation. A tunable bandpass filter is presented that allows a prototype IIR or FIR filter to be shifted through the entire range of digital frequencies from DC to the Nyquist frequency. When a highpass or lowpass filter with a sufficiently small passband (<0.5��), the resulting output is a bandpass filter with twice the bandwidth. In digital wireless personal mobile communication systems, the tunable bandpass filter can be used very effectively in the elimination of narrow band interference in wideband communications.