Security listening system

Details Security listening system Security listening system

1983-12-05

1985-07-02

Rubinson, Gene Z.

179 2A, H04M 1100

Patent

active

045270155

ABSTRACT:
A security listening system activated by and transmitting over telephone lines to allow listening for sounds at a remote location over a standard telephone line using a standard telephone instrument at the calling end. The system is connected at the remote site to be monitored across the telephone standard tip/ring pair either in parallel with the standard telephone instrument or in lieu thereof. The system is powered by D.C. voltage obtained by rectifying the telephone voltage or, optionally, by a battery. The unit monitors ring sequences on the telephone line and after a pre-established number, activates the balance of the device. If thereafter during a fixed time duration a pre-established tone signal of minimum duration or longer is applied to the line, the system connects a microphone and amplifier across the telephone line to allow the listener on the other end to hear what is happening in the surrounding area. If the tone is not applied to the line before the timed duration expires, the device deactivates. The need for a tone to connect the microphone is optional.

REFERENCES:
patent: 3530250 (1970-09-01), Schaum et al.
patent: 4095050 (1978-06-01), Beachem et al.
patent: 4353502 (1982-10-01), Myers

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