Telephonic communications – Telephone line or system combined with diverse electrical... – To produce visual-graphic copy
Patent
1991-04-30
1993-01-19
Dwyer, James L.
Telephonic communications
Telephone line or system combined with diverse electrical...
To produce visual-graphic copy
379 28, 379 93, 34087002, H04M 1100
Patent
active
051812410
ABSTRACT:
A data transmission system uses a malfunction detection circuit for detecting malfunction conditions between a data transmitting station and a data receiving station connected with first and second data transmission lines. The malfunction circuit senses a data signal of a first polarity for a preselected duration and provides an output signal when the data signal exceeds the preselected duration. The circuit also supplies a detection signal of a second preselected duration in a polarity opposite the data signal and detects the presence of or the absence of the detection signal. The circuit thereafter provides an output signal indicative of the malfunction condition when the absence of the detection signal exceeds the second preselected duration.
REFERENCES:
patent: 4337466 (1982-06-01), Spahn
patent: 4357601 (1982-11-01), McWilliams
patent: 5025470 (1991-06-01), Thornborough et al.
Gomez Greg M
Pridemore Donald F.
Strobel Donald H.
Badger Meter Inc.
Chan W. F.
Dwyer James L.
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