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介绍了作为语音识别系统的基本环节之一——采样前置带通滤波器的研制情况,对采样前置滤波器的滤波特性的确定原则进行了讨论,提出应如何选择带通滤波器的上限截上频率和采样速率,确保混叠发生在感兴趣频带之外,借以减小混叠误差。所研制的采样前置GIC 椭圆带通滤波器由八阶高通和九阶低通滤波器串联构成,所用的运算放大器数目较多。为了得到预期的滤波特性,保证各运算放大器工作在合理的状态,作者设计了零电平调整电路,使得滤波器的调试变得容易,性能指标满足要求。
Introduced as a speech recognition system, one of the basic aspects - the development of sampling pre-band-pass filter, the sampling pre-filter characteristics of the filter to determine the principle were discussed how to choose the upper limit of the band-pass filter Cut off the frequency and sampling rate to ensure that aliasing occurs outside the band of interest to reduce aliasing errors. The sampling pre-GIC elliptical band-pass filter developed by the eighth-order high-pass and nine-order low-pass filter in series, the use of a larger number of operational amplifiers. In order to get the expected filter characteristics, to ensure that the operational amplifier in a reasonable state, the author designed a zero-level adjustment circuit, making the filter easier to debug, performance indicators to meet the requirements.