Telephonic communications – Supervisory or control line signaling – Using line or loop condition detection
Patent
1995-10-27
1998-01-06
Zele, Krista
Telephonic communications
Supervisory or control line signaling
Using line or loop condition detection
379194, 379373, 379377, 379387, H04M 322, H04M 168
Patent
active
057063427
ABSTRACT:
An apparatus for detecting an off-hook condition on a telephone, the apparatus being connected to the tip line and the ring line of a telephone line, a first potential difference existing between the tip line and the ring line, the telephone line connected to the telephone having a handset. A circuit generates a difference signal representative of the absolute value of the first potential difference. A first comparator, responsive to the difference signal, generates a first indicator signal when the difference signal is above a first value corresponding to a maximum value of potential difference between the tip line and the ring line when the handset is off-hook. A second comparator, responsive to the difference signal, generates a second indicator signal when the difference signal is below a second value corresponding to a minimum value of potential difference between the tip line and the ring line when the handset is off-hook. A circuit, responsive to the first indicator signal and the second indicator signal, indicates when the handset is off-hook.
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Baeder David J.
Ciosek Richard F.
Business Link International
Kumar Devendra T.
Zele Krista
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