| Summary: | 碩士 === 大同大學 === 通訊工程研究所 === 97 === The concept of Software Define Radio (SDR) is to remove the mixers, and to place the analog-to-digital converters (ADC) as close as possible to the antenna, then we can use program to implement more capabilities of communication system. Bandpass sampling is an undersampling technique, it realizes frequency down-conversion, and provides an interface between the IF stage and ADC. Bandpass sampling becomes more and more attractive for SDR.
Noise aliasing is a direct consequence by bandpass sampling, due to the thermal noise from circuit network, bandpass sampling with noise gives raise the noise power, such that the signal to noise ratio (SNR) is degraded. In this paper, using a generalized quadrature bandpass sampling with FIR filtering to eliminate the image band, and reduction the noise aliasing to give raise the SNR of the system performance.
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