Telephone battery feed circuit including noise reduction circuit

Details Telephone battery feed circuit including noise reduction circuit Telephone battery feed circuit including noise reduction circuit

1994-09-28

1996-06-18

Hofsass, Jeffery

Telephonic communications

Subscriber line or transmission line interface

Network interface device

379377, 379395, 379382, 379399, H04M 1900

Patent

active

055286887

ABSTRACT:
A circuit and method minimizes undesired noise signals associated with the battery utilized in a telephone battery feed circuit. In one embodiment, the noise voltage is amplified and inverted in phase and added back to a location on the ring line in order to provide substantial cancellation of the original noise voltage which would have appeared at the same location. In another embodiment, the noise voltage coupled to the ring line is reproduced as a replica signal. The replica signal is added in series with the tip line so as to provide equal phase and magnitude relationships relative to earth ground, thereby effectively canceling the noise current which would have flowed from the original noise source.

REFERENCES:
patent: 4007335 (1977-02-01), Hetherington et al.
patent: 4267408 (1981-05-01), Schoofs
patent: 4306122 (1981-12-01), Nijman et al.
patent: 4402039 (1983-08-01), Jirka
patent: 4419542 (1983-12-01), Embree et al.
patent: 4476350 (1984-10-01), Aull et al.
patent: 4588860 (1986-05-01), Ayano et al.
patent: 4612417 (1986-09-01), Toumani
patent: 4736415 (1988-04-01), McNeill et al.
patent: 4764956 (1988-08-01), Rosch et al.
patent: 5337354 (1994-08-01), Gadsby
patent: 5444777 (1995-08-01), Condon et al.

Affiliated with

Also associated with

Rating

Telephone battery feed circuit including noise reduction circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Telephone battery feed circuit including noise reduction circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telephone battery feed circuit including noise reduction circuit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-229625