Direct connect modem deriving power from telephone line

Details Direct connect modem deriving power from telephone line Direct connect modem deriving power from telephone line

1989-11-17

1992-02-04

Dwyer, James L.

Telephonic communications

Telephone line or system combined with diverse electrical...

Having transmission of a digital message signal over a...

375 8, H04M 1100

Patent

active

050864548

ABSTRACT:
A telephone modem which is at least partially powered by electrical power from a telephone line to which it is connected and which is further powered by a local power source, such as power extracted from digital serial data lines to which it is coupled or from a battery source or a combination thereof. Telephone line power is used to operate all analog signal processing, and local power is used to operate the remainder of the modem, including digital signal transmission, reception and manipulation, as well as modem control functions. In a preferred embodiment, optical isolation means provide isolation between differently-powered segments of the modem circuitry. The analog signal processing segment is coupled to the telephone line in a manner which maintains line current requirements and constant a.c. impedance, and regulated power is derived from the intermittent telephone line power source. In a further specific embodiment, charge pump circuitry is employed to extract both positive and negative inverted power from the digital serial data signal line for use as local power.

REFERENCES:
patent: 4373117 (1983-02-01), Pierce
patent: 4415774 (1983-11-01), Driver
patent: 4417099 (1983-11-01), Pierce
patent: 4578533 (1986-03-01), Pierce
patent: 4656318 (1987-04-01), Noyes
patent: 4691344 (1987-09-01), Brown et al.
patent: 4777577 (1988-10-01), Bingham et al.
patent: 4797899 (1989-01-01), Fuller et al.
patent: 4803719 (1989-02-01), Ulrich

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