公开(公告)号：DE2320656A1

公开(公告)日：1973-11-08

申请号：DE2320656

申请日：1973-04-24

Applicant: INTEGRATED SYSTEMS TECHNOLOGY

Inventor： GARCIA HERNANDO JAVIER ,  PEEK BENJAMIN R

IPC: H03B5/32 ,  H03B1/00 ,  H03B5/36 ,  H03L1/02 ,  H03B5/04

公开(公告)号：DE2247939A1

公开(公告)日：1973-04-05

申请号：DE2247939

申请日：1972-09-29

Applicant: INTEGRATED SYSTEMS TECHNOLOGY

Inventor： GARCIA HERNANDO J ,  PEEK BENJAMIN R

IPC: H03M1/82 ,  H03K3/0231 ,  H04Q1/50 ,  H04Q1/45

Abstract: A relaxation oscillator is formed by a Schmitt trigger circuit and an operational integrator circuit interconnected to form an oscillatory feedback loop. A diode switching network is constructed to receive a plural-bit digital input signal and to modify a circuit parameter in the oscillator feedback loop to adjust the frequency of oscillation in accordance with the coding of the digital input signal. An active low-pass filter circuit is connected to the output of the operational integrator circuit and supplies a sinusoidal tone signal to an output circuit. A switching circuit is responsive to the digital input signal for disabling the output circuit except during the occurrence of predetermined digital code values.

公开(公告)号：DE2310981A1

公开(公告)日：1973-10-11

申请号：DE2310981

申请日：1973-03-06

Applicant: INTEGRATED SYSTEMS TECHNOLOGY

Inventor： GARCIA HERNANDO J ,  PEEK BENJAMIN R

IPC: H04W52/02 ,  H04W88/02 ,  H04B1/38

公开(公告)号：DE2248332A1

公开(公告)日：1973-04-12

申请号：DE2248332

申请日：1972-10-02

Applicant: INTEGRATED SYSTEMS TECHNOLOGY

Inventor： GARCIA HERNANDO J ,  PEEK BENJAMIN R

IPC: H04Q1/446 ,  H04W88/02 ,  H04Q1/45

Abstract: There is disclosed a tone detector system which is particularly useful in communications systems for detecting audio-frequency signalling tones transmitted from one station to another. The disclosed tone detector system includes an amplifier followed by a limiter. The limiter drives a pair of signal channels each of which includes a tuned amplifier followed by a tone-to-digital converter. The tuned amplifier in each channel is provided with a pair of frequency selective filters, one or the other of which is used depending on the operating mode of the communications equipment. Interlock circuitry cross couples the outputs of the two tone-to-digital converters so that a tone signal indicative digital output signal can appear at the output of only one of the tone signal channels at any given instant.