Telephone answering machines

Details Telephone answering machines Telephone answering machines

1975-07-25

1977-01-18

Pitts, Harold I.

Communications: electrical

Digital comparator systems

340171PF, 340151, H04Q 900

Patent

active

040042766

ABSTRACT:
A remotely controllable electrical equipment is fitted with a decoder device associated with which is an unlocking circuit. Access to the electrical equipment is obtained by transmitting an access signal from a remote coder device. The access signal is made up of three groups of pulsed electrical signals, each group comprising two pulses of frequencies different from each other. The first group of pulses unlocks the unlocking circuit for a first predetermined interval of time. If the second group of pulses arrives within this first predetermined interval of time the unlocking circuit is unlocked for a second predetermined interval of time. If the third group of pulses arrives in the second predetermined interval of time an output signal is applied to the associated electrical equipment. Control signals for operating the equipment can then be transmitted from the coder device to the equipment via the decoder device.

REFERENCES:
patent: 3035250 (1962-05-01), Durkee
patent: 3039081 (1962-06-01), Smith
patent: 3060408 (1962-10-01), Stewart
patent: 3092829 (1963-06-01), Kleist
patent: 3588826 (1971-06-01), Vaccaro

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