Fibre=optic transmission line transmission level monitoring circuit

摘要

The circuit includes a receiver (12) with a digital and an analogue output (14,16). A received signal is accessible at the digital output, and a parameter proportional to the received light quantity is accessible at the analogue output. The digital output is connected to a clock input (26) of a counter (28) and the analogue output is connected to an input of a selection circuit (42) whose output is connected to a reset input of the counter circuit. A warning signal is output (30) from the counter circuit if the parameter at the output of the analogue circuit exceeds a preset threshold.- DETAILED DESCRIPTION - A method of monitoring the transmission level of a fibre-optic transmission line is also claimed