Overview

The WIRE card is designed to interface the wire-line communication signal to the WRAT Bell 202 piggy-back modem. Automation Electronics WIRE Wireline Interface Module

Automation Electronics WIRE Wireline Interface Module

It consists of equalization circuitry designed to match the impedance of the wire-line. The transmit equalization circuit on the WIRE card is optically coupled. It's designed such that it

matches the impedance of the wire-line (typically 600 Ohms) in transmit mode
turns into a high input impedance card (50 kOhms) in receive mode.

This allows for maximum power transfer.

A transmit LED is provided on the WIRE card, which turns on when the modem is transmitting data. The WIRE card also has transient protection circuitry that has been tested with the IEEE 472.1974 surge tests.