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Full-Duplex Coaxial Cable Link

IP.com Disclosure Number: IPCOM000034585D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Hsu, PYT: AUTHOR [+2]

Abstract

A coaxial cable link can be arranged to handle full-duplex communications at megahertz rates, maintain high link impedance, prevent concurrent signal transmission, and provide Clear To Send output signals and interpret Request To Send input signals. A diagram of a full-duplex interface to a coaxial cable is shown in the figure. Coaxial cable 1 is connected at each end with a double- ended transmitter 2,3 and differential receiver 4,5 that are capable of being disconnected from the line when placed in the high impedance (tri-state) condition. The transmitters have a series source termination to dampen line reflections with the source resistor 6 matched to line impedance.

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Full-Duplex Coaxial Cable Link

A coaxial cable link can be arranged to handle full-duplex communications at megahertz rates, maintain high link impedance, prevent concurrent signal transmission, and provide Clear To Send output signals and interpret Request To Send input signals. A diagram of a full-duplex interface to a coaxial cable is shown in the figure.

Coaxial cable 1 is connected at each end with a double- ended transmitter 2,3 and differential receiver 4,5 that are capable of being disconnected from the line when placed in the high impedance (tri-state) condition. The transmitters have a series source termination to dampen line reflections with the source resistor 6 matched to line impedance. The receivers have high impedance inputs, and their outputs react to voltage differential at the inputs to reject common- mode noise likely to be picked up by the cable. The electrical connection between the cable ends is a high impedance so that there is no danger of large currents due to induced voltages.

One transmitter at a time is active with the other placed in high impedance mode to disconnect it from the line. In this state, impedance at the receiver end is nearly infinite and impedance at the source is matched to the line, making receiver voltage a faithful replica of transmitter voltage in spite of reflected waves. The interfaces at each cable end can be connected to full-duplex devices.

When transmission is from a transmitter, such as 2, to receiver 5, tra...