| 摘要 |
1,250,393. Formant vocoder analyser. PHILCO-FORD CORP. 23 Jan., 1969 [25 Jan., 1968], No. 3860/69. Heading H4R. A formant frequency tracking circuit for a vocoder has a variable frequency tuned filter, 4, whose tuning is controlled by the output of the formant frequency detector, 8, to provide an emphasis of the frequency band around the detected formant. The band pass filter 2 provides selection of the formant frequency range 14 as shown in Fig. 2 with direct coupling via resistor 6 to the frequency meter, the resistor being by-passed at the frequency of the tuned filter to provide a peak 16 in the response. The arrangement provides a sort of hysteresis effect in the frequency tracking. |
