| 摘要 |
<p>The device discriminates speech in an input signal formed by a spoken word signal mixed with noise. The input signal enters a band-pass filter (3) to limit its frequency band. The input signal is also applied to a band-stop filter (5), centered on the mean frequency of the first format of the input signal, and which covers a portion of the frequency band of the first formant. The signal from the band-stop filter (5) is detected (6) with a long time constant corresponding to that of the noise, and the signal from the band-pass filter (3) is detected (7) with a short time constant corresponding to the syllabic time constant. The difference (Vd) between both detectors output (V',kV) is compared with a threshold (Vo). The circuit may be used in a voice-operated transmit-receive switching system for a transceiver.</p> |
