Bidirectional frequency shift coding using two different codes for upstream and downstream

摘要

A method of transmitting bidirectional telephony communication signals on a single optical fiber. The bidirectional signals are transmitted in one direction as NRZ coded signals at a first clocking pulse rate, and in the other direction as Manchester coded signals at a second clocking pulse rate which is a multiple (preferably three times (3x)) of the first clocking pulse rate.