Wideband optical propagation measurement system for characterization of indoor wireless infrared channels

Present the design of a measurement set-up being used for characterizing an indoor wireless infrared communication system. This consists of an optical transmitter with a high-power laser diode and an optical receiver with a large-area avalanche photodiode. The receiver bandwidth, limited by the large capacitance and the long transit-time of the avalanche photodiode, is extended to 400 MHz using a transimpedence receiver design and a resonant-type analog equalizer. Some typical measured results are presented in the paper, as well. The impact of shadowing and receiver orientation on the channel frequency response are also shown for both line-of-sight and diffuse configurations