Telephonic communications – Transmission line conditioning – Interference suppression
Patent
1989-02-03
1990-08-28
Ng, Jin F.
Telephonic communications
Transmission line conditioning
Interference suppression
379399, 379414, H04B 332
Patent
active
049532065
ABSTRACT:
In a system (20) for transmitting voice and data signals, insulated metallic conductor pairs (44--44) which transmit data signals and insulated metallic conductor pairs (46--46) which are capable of transmitting voice signals are enclosed in a common sheath system of a single cable (40). User pickup of station apparatus (34) during the generation of a ringing voltage on a voice conductor pair causes that pair to become disturbing and to impart impulse noise to a closely coupled data pair. The data pair is designated a disturbed pair and the signals transmitted thereby may be affected adversely. This problem is overcome by providing a circuit (80) comprising in parallel a resistance and an inductance and being in series with the station apparatus. Such an arrangement reduces substantially that frequency content of any disturbing signal which appears on the disturbing pair and which is in the range of the data signal spectrum. This reduces the magnitude of crosstalk between the voice and data pairs and results in substantially error-free transmitted data.
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Friesen Harold W.
Haber Janice B.
Nutt Wendell G.
AT&T Bell Laboratories
Ng Jin F.
Somers Edward W.
Vaas Randall S.
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