Circuit arrangement for controlling a voice-frequency spectrum by means of binary signals

Abstract

Abstract 997,897. Formant tracking vocoders. TELEFONAKTIEBOLAGET L. M. ERICSSON. Sept. 12, 1963 [Sept. 17, 1962], No. 36069/63. Heading H4R. A synthesizer for a formant tracking vocoder in which the formant frequencies are transmitted as digital signals comprises, Fig. 2, a series parallel converter for each formant to convert the serial binary number on the line to a parallel form so that triggers, e.g. VII to V14, may be actuated and, via a diode matrix, operate a transistor switch to connect the appropriate one of capacitors C1 to C16, in parallel with the inductance L so tuning the inductance L to the frequency appropriate to the binary signal received from the line. The tuned circuits for each formant, e.g. F1 and F2 in Fig. 2, are serially connected to the output of a spectrum generator to obtain the synthesized speech. Fig. 3 shows in detail how the output of the diode matrix BO causes conduction of one of the transistors T1 to T16, in accordance with the binary input to the triggers, so connecting the appropriate one of capacitors C1 to C16 to tune the inductance L to the required frequency. The emitter follower amplifiers Ta and Tb, Tc, are provided to match the inductive circuit to the preceding and following circuits. Resistors R1 to R16 are connected in parallel with the tuning capacitors C1 to C16 to adjust the bandwidths of the tuned circuits to the required values.

Inventors

• 👤 Vollmer Burghardt Herman Josef

Bibliographic Details