| 摘要 |
A digital spectral normalizer for subtracting out the mean of an input signal to be normalized to obtain a normalized output signal. The normalizer comprises a variable gain amplifier which adjusts the input level to fall within the dynamic range of an analog to digital converter. The output of the digital converter propagates along two paths, i.e. one path used to drive a first digital to analog converter which provides the analog levels to a first low pass filter to obtain the mean of the input signal and the second path used to delay the output of the digital converter by an amount selected in a digital delay line to match the inherent delay of the mean signal traveling via the first path. The delayed signal drives a second analog to digital converter, the output of which passes through a second low pass filter of relatively high frequency, restoring the quantized waveform back to continuous analog signal. The mean signal is then subtracted from the delayed signal in the output amplifier to obtain the normalized output signal.
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