A Multi-Channel Fibre-Optic Link for Analog Telemetry

Abstract

Control of an ion beam injector requires a reliable telemetry link for analog signals between the high voltage dome and ground. This paper describes a self-scanning, self-checking system capable of transmitting up to sixteen channels of analog data (in each direction) with eight bit resolution over a dual light link. The technique used is serial transmission of eight bit words using standard UART's (Universal Asynchronous Receiver Transmitter) which provide much of the error detection and timing. Two versions, one stand-alone for manual control, the other an input/output interface board that plugs into a control microcomputer, have been designed. For sixteen channels, the data is updated every 3.2 milliseconds. The simple design and low parts count provide a low cost analog telemetry system.