Local area networks

Claim 2

. A local area network for generalized data signal communications between two or more workstations (51) in a campus or short distance environment, including means for coupling said workstations means comprising the existing telephone wiring (57) in the said environment.

Claim 3

The local area network as claimed in Claim 1, including telephone equipment means (30) for conducting normal voice communication over coupling means.

Claim 4

The local area network as claimed in Claim 2, further including circuit means (Fl, F2) for excluding said data signals from said voice communication, and said voice communication from said data signals, said data signal communications and said voice communication being capable of concurrent operation.

Claim 5

The local area network as claimed in Claim 3, wherein said coupling means includes: means for generating high-frequency signals representative of said data signals, and means for generating low-frequency signals representative of said voice communications.

Claim 6

The local area network as claimed in Claim 4, further including: a plurality of high-pass filter means (Fl) to pass only said high-frequency signals to and from said workstations, and a plurality of low-pass filter means (F2) to pass only said low-frequency signals to and from said telephone equipment means. 6. The local area network as claimed in Claim 3, further including means for operating said data signal communication and said voice communication in a data-over-voice mode. 7. The local area network as claimed in Claim 3, further including means for operating said data signal communication and said voice communication in a voice-only mode.

Claim 7

The local area network as claimed in Claim 2, or any claim dependent further therefrom including: node unit circuit means (53) coupled between individual workstations and the immediate local telephone link, said node unit circuit means providing a first communication interface between a workstation and said local telephone link, and repeater unit circuit means (55) at the local junction location or telephone closet for coupling local telephone links to the rest of the local telephone system, said repeater unit circuit means providing a second communication interface between various workstations coupled thereto, said node unit circuit means and said repeater unit circuit means also providing a path for normal telephone voice communications.

Claim 8

The local area network as claimed in Claim 8, wherein said node unit circuit means further includes: line driver circuit means for generating and transmitting high-frequency baseband data signals in response to data received from its associated workstation, line receiver circuit means for receiving and transferring to its associated workstation any high-frequency baseband data signals received from the telephone link, and line termination circuit means for terminating the telephone line at its characteristic impedance at the baseband signal frequency.

Claim 9

The local area network as claimed in Claim 9, further including: first filter means coupled to said telephone link so that any low-frequency signal components in said high-frequency baseband signals from said workstation are not transmitted, so as not to degrade the voice communications, and second filter means coupled to said telephone link and any telephone equipment so that said high-frequency baseband signals do not reach said telephone equipment in data-over-voice situations.

Claim 10

I1. A driver-receiver circuit wherein the circuit is disabled if: a signal appears at its output terminal before a signal appears at its input terminal, including input terminal means for receiving a signal to be amplified, delay circuit means coupled to said input terminal means for delaying for a predetermined period a signal to be amplified, amplifier means coupled to said delay means for amplifying a signal to be amplified, output terminal means for receiving and directing an amplified signal to subsequent circuitry, first one-shot circuit means coupled to said input terminal means, said first one-shot circuit means having a trigger input and an output, said first one-shot circuit means being triggered by the receipt of a signal to be amplified, second one-shot circuit means having a trigger input, a disable input, and an output, said trigger input being coupled to said output means and responsive to a signal on said output terminal means, the disable input being coupled to said output of said first one-shot circuit means and responsive to the signal generated by said first one-shot circuit means upon receipt of a signal to be amplified received by both said delay circuit means and said trigger input of said first one-shot circuit means, the output of said second one-shot circuit means being coupled to disable said amplifier means such that if and when a separate signal appears at said output terminal, said second one-shot circuit means will be triggered in response thereto to disable said amplifier means before a signal to be amplified, if present at said input terminal at the same time a signal appears at said output terminal, can be amplified by said amplifier means.

Claim 11

I1. A driver-receiver circuit wherein the circuit is disabled if: a signal appears at its output terminal before a signal appears at its input terminal, including input terminal means for receiving a signal to be amplified, delay circuit means coupled to said input terminal means for delaying for a predetermined period a signal to be amplified, amplifier means coupled to said delay means for amplifying a signal to be amplified, output terminal means for receiving and directing an amplified signal to subsequent circuitry, first one-shot circuit means coupled to said input terminal means, said first one-shot circuit means having a trigger input and an output, said first one-shot circuit means being triggered by the receipt of a signal to be amplified, second one-shot circuit means having a trigger input, a disable input, and an output, said trigger input being coupled to said output means and responsive to a signal on said output terminal means, the disable input being coupled to said output of said first one-shot circuit means and responsive to the signal generated by said first one-shot circuit means upon receipt of a signal to be amplified received by both said delay circuit means and said trigger input of said first one-shot circuit means, the output of said second one-shot circuit means being coupled to disable said amplifier means such that if and when a separate signal appears at said output terminal, said second one-shot circuit means will be triggered in response thereto to disable said amplifier means before a signal to be amplified, if present at said input terminal at the same time a signal appears at said output terminal, can be amplified by said amplifier means.

Claim 12

A local area network (LAN) for generalized data signal communication between two or more workstations in a campus or short distance environment, including: ordinary telephone wiring means in said environment for coupling said workstations, and further including network circuit means for providing completely general connectivity between workstations via logical virtual connections instead of point-to-point switched circuit connections, as provided by said telephone circuits for data communication.

Claim 13

A local area network (LAN) for generalized data signal communication between two or more workstations in a campus or short distance environment, including: ordinary telephone wiring means in said environment for coupling said workstations, and further including network circuit means for providing completely general connectivity between workstations via logical virtual connections instead of point-to-point switched circuit connections, as provided by said telephone circuits for data communication.