Telephonic communications – Multi-line or key substation system with selective switching... – With intercom system
Patent
1987-04-23
1988-10-04
Ng, Jin F.
Telephonic communications
Multi-line or key substation system with selective switching...
With intercom system
370 76, 379164, 379387, 379396, H04M 172, H04M 9100
Patent
active
047760060
ABSTRACT:
A multiplexed data channel telephone system comprising a master station (221) and one or more remote stations (222) is disclosed. Each station (221, 222) is bridged, in a parallel electrical connection, onto a wire-pair (201) that extends from the stations to a telephone switching system. Each station (221, 222) includes a voiceband line interface (110, 310) for connecting to the wire-pair (201) at voiceband frequencies, and a radio frequency line interface (700, 800) for connecting to the wire-pair (201) at radio frequencies. Each station further includes multiplexer and demultiplexer equipment (500, 600) for frequency shifting a data channel between baseband and rf. Amplitude modulation and half-duplex transmission are used in the data channel. Telephone status and control information, including ringing and answer control, are exchanged between controllers (160, 360) via the data channel. Remote stations (222) minimize the amount of equipment required by using the data channel to control common equipment at the master station (221) that interacts with incoming telephone lines (201, 202).
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(Publication) ITT, "EKS-701 Electronic Key Telephone System", Feb. '83, Front Page.
"MCD Aids Small Phone Systems", Electronic Engineering Times, Warren Andrews, 3/10/86, page 44.
Comerford Timothy N.
Holliday Jan R.
McLane Michael J.
AT&T Bell Laboratories
Chan Wing Fu
Morra Michael A.
Ng Jin F.
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