4W circuit vs 2W circuit-Difference between 4W and 2W telephone circuit

This page on 4W circuit vs 2W circuit describes difference between 4W and 2W telephone circuits.

As we know these terminologies are used in telephone circuits. 4W stands for 4 Wire and 2W stands for 2Wire. Two wires are used between telephone subscriber terminal set and analog line interface to minimize line cable costs. Transmission and reception occur in the same two wires of the local loop. Four wires are used for longer distance trunks between the exchange branches in order to isolate transmitted and received signals.

2W 4W telephone hybrid circuit

The separation of transmit and receive signals in the analog line interface at the CO is achieved using hybrid transformer.

EXAMPLE: MC3419 motorola IC works as hybrid transformer.

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