公开(公告)号：US3020344A

公开(公告)日：1962-02-06

申请号：US7836360

申请日：1960-12-27

Applicant: BELL TELEPHONE LABOR INC

Inventor： PRESTIGIACOMO ANTHONY J

IPC: G10L25/93

CPC classification number: G10L25/93

Abstract: 918,941. Vocoders. WESTERN ELECTRIC CO. Inc. Dec. 7, 1961 [Dec. 27, 1960], No. 43803/61. Class 40 (4). In a pitch signal generator and voiced-unvoiced detector the peaks of a signal representing a portion of the speech band are sampled and a unidirectional signal is derived from the largest of the sampled peaks and this signal is compared with the average value of the speech signal to determine whether the speech is voiced or unvoiced and the signal is also used to generate a further signal indicative of the pitch of the speech. Fig. 2 shows a pitch detector in which speech from microphone 10 has its polarity adjusted, via switching circuit 2, so that its maximum peaks are negative joining, this signal is limited to the band 0-300 c.p.s. in filter 201 and applied to the sampling pulse generator 202 and sampler 203. Sampling pulses to apply to sampling circuit 203 are obtained by differentiating and infinitely clipping the band limited speech wave to obtain a rectangular wave the axis crossings of which correspond to peaks in the speech wave. The positive-going axis crossings, corresponding to negative-going peaks, trigger monostable multivibrator 23 to generate the sampling pulses. Pulses from generator 202 control a transistor gate, Fig. 4, not shown, to feed samples of the peaks of the band limited speech to peak rectifier 31; Fig. 3B shows the band limited speech, Fig. 3G the samples at the negative-going peaks and Fig. 3H the output of peak rectifier 31 showing how positive-going samples are eliminated and how spurious pulses such as Vs, of lower amplitude than those derived from the maximum negative peaks are largely ignored if the time constant of the peak rectifier is suitably chosen. The averaged sawtooth wave is compared on the base of transistor 51 with the rectified filtered speech wave. from source 10. Dependent on the relative magnitudes of these signals transistor 51 is switched either on or off resulting in a two level voicedunvoiced signal. The sawtooth wave is also converted into a pulse waveform in generator 204 which is applied together with the voicedunvoiced signal to " and " gate 206 to eliminate spurious pitch pulses from the output during unvoiced sounds. Specification 466,327 is referred to.

公开(公告)号：US3355551A

公开(公告)日：1967-11-28

申请号：US37295564

申请日：1964-06-05

Applicant: BELL TELEPHONE LABOR INC

Inventor： PRESTIGIACOMO ANTHONY J

IPC: G01R23/00 ,  G10L21/06

CPC classification number: G01R23/00 ,  G10L21/06

Abstract: 1,102,779. Recording and playback. WESTERN ELECTRIC CO. Inc. 27 May, 1965 [5 June, 1964], No. 22516/65. Heading G5R. [Also in Division G1] In an apparatus for analysing complex signals carried on a magnetic tape 101 (Fig. 1) a portion of the tape is fed from a reel 10 to a supply reel 21 via sensing head 12 and periodically stopped on the periphery of a drum 17 and repeatedly scanned, by a head rotating inside the drum. During each rotation at a particular stop, the output signal is modulated by a different frequency, the resulting beat frequency being filtered by a fixed frequency filter, to provide an output corresponding to a particular frequency in the spectrum of the original signal. The selected portion of tape is clamped under tension at each step, it being arranged that the operation of the tensioning system is delayed relative to the clamp at each stop. The tensioning and clamping system is released and the record advanced by a preselected interval after the portion has been analysed in order to select the next contiguous portion of the record. The outputs are successively recorded by a stylus 22 on a record 39 carried on a drum 23 rotated in synchronism with the rotating head. The amplitude of a mark on the record 39 corresponds to the signal amplitude at any particular frequency, the frequency corresponding to the position across the medium, while distance along the medium corresponds to time. A more detailed description of the operating system circuitry is given (see Division G1).

公开(公告)号：US3139487A

公开(公告)日：1964-06-30

申请号：US7866060

申请日：1960-12-27

Applicant: BELL TELEPHONE LABOR INC

Inventor： LOGAN JR BENJAMIN F ,  PRESTIGIACOMO ANTHONY J

IPC: H04B1/66

CPC classification number: H04B1/667 ,  H04B1/66