| 摘要 |
A squelch circuit for a radio receiver that detects the presence of speech by utilizing a filter bank for filtering an intermediate frequency or baseband signal from the radio receiver into band-pass signals, detecting the magnitude of the band-pass signals, and separating the signal magnitudes into a speech and noise detector. The speech detector determines if speech is present by determining if syllabic variations are present in the speech detector signals and selects a voice band average signal with a maximum difference in syllabic variations, and generates a speech detector decision when speech is present. The noise detector makes a noise detector decision when speech is present by obtaining a minimum noise detector signal and comparing the minimum noise detector signal to a threshold scaled voice band average signal associated with the maximum difference in syllabic variations. A final decision is made when the speech detector decision and the noise detector decision both indicate speech and the audio output is enabled and held on for a predetermined hold time.
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