Telephonic communications – Supervisory or control line signaling – Signal receiver
Patent
1994-05-31
1997-03-04
Matar, Ahmad F.
Telephonic communications
Supervisory or control line signaling
Signal receiver
363 21, 379322, 379387, 379413, H04M 1900
Patent
active
056087926
ABSTRACT:
Apparatus powered from a communications line minimizes current drawn from the line by use of a variable power supply having a DC to DC conversion circuit controlled by an oscillator. The output of the DC to DC conversion circuit in a first lower power drawing mode is used to power a tone detection circuit which monitors the line for a wake-up tone. On receipt of an appropriate wake-up tone, the tone detection circuit provides an interrupt signal to a microprocessor which, in response, causes an increase in the oscillator frequency. The increased oscillator frequency then increases power drawn from the line via the DC to DC conversion circuit for operation in a second higher power drawing mode.
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British Telecommunications public limited company
Matar Ahmad F.
Wolinsky Scott
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