A receiver for a pulse-echo ranging system with digital polyphase decimation filter

摘要

A receiver for a pulse-echo ranging system comprises an analog-to-digital converter (ADC) for digitizing a received raw echo, a finite impulse response (FIR) filter (1) for band-pass filtering the digitized echo (x[n]) and an envelope detector for detecting the envelope of the band-pass filtered echo.;In order to obtain a very high processing speed and allow the receiver easily adjustable to measurement conditions with different noise levels or systems working with different carrier frequencies, the FIR filter (1) comprises an efficient polyphase decimation filter having M branches with an 1/M down-sampler (2) and a subfilter (4) in each branch, where M is the quotient of the sampling rate of the ADC and at least approximately twice the occupied bandwidth of the pulse.