Telephonic communications – Telephone line or system combined with diverse electrical... – Having transmission of a digital message signal over a...
Patent
1985-06-17
1988-02-02
George, Keith E.
Telephonic communications
Telephone line or system combined with diverse electrical...
Having transmission of a digital message signal over a...
379443, H04M 1100
Patent
active
047232676
ABSTRACT:
Apparatus (10) for providing isolation and interconnection between the tip (1) and ring (2) conductors of a telephone line and data communications equipment to be connected thereto, such as a modem or other device (12). The apparatus serves also as a circuit for dialing the telephone, responsive to dialing signals applied thereto. All switching is done electronically, eliminating the need for mechanical relays. A diode bridge (18) is connected to the tip (1) and ring (2) conductors of the telephone line; the active circuitry of the interface derives power through the bridge. A switchable constant-current load (48, 20, 22) is placed across the output nodes of the bridge. The load is switched by an opto-isolator (40) which, in turn, is controlled by the line-seizing switch of the data communications equipment. When the line-seizing switch is closed (i.e., the device is off-hook), the opto-isolator (40) causes the switchable load to place a low impedance d.c. load across the tip and ring conductors while presenting a high a.c. impedance, for drawing the necessary current to seize and hold the line. When the hook switch is open (i.e., the device is on-hook), the load is switched off, presenting a high d.c. impedance as well as a high a.c. impedance. Make-break dialing is accomplished by applying dialing pulses to the same control line (38) as connects to the line-seizing switch.
REFERENCES:
patent: T949003 (1976-08-01), Earle et al.
patent: 3595999 (1971-07-01), Cole
patent: 4104486 (1978-08-01), Martin et al.
patent: 4203006 (1980-05-01), Mascia
patent: 4241237 (1980-12-01), Paraskevakos et al.
patent: 4306116 (1981-12-01), McClure et al.
patent: 4500754 (1985-02-01), Mackey
patent: 4558183 (1985-12-01), Corris et al.
patent: 4640988 (1987-02-01), Robinton
patent: 4656318 (1987-04-01), Noyes
Telephony's Dictionary, .COPYRGT. 1982, Telephony Publishing Co., TK 5102 L3, p. 96.
Edison et al., "Integrated Data Communication Systems", Proceedings of the National Electronics Conference, vol. 37, 1983, Oak Brock, Ill., U.S., pp. 507-515.
R. Lambley, "Multi-Standard Modem", Wireless World, vol. 90, No. 1582, July 1984, pp. 45-47.
Davison Ian R.
Jones Kenneth D.
George Keith E.
Iandiorio Joseph S.
Octocom Systems, Inc.
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