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Design of receivers for free-space FM optical video systems

This paper considers the design and performance of a tuned front-end receiver for use in a free-space optical video systems system. The use of front-end tuning is advantageous as it enables large area optical collectors to be employed, it reduces receiver noise and it eliminates the problematic L.F. emissions that emanate from typical lighting sources. Results are presented that show the receiver produced enables a 50 dB weighted SNR to be achieved at a received optical power of -32.7 dBm and threshold to be achieved at a received optical power of -39.5 dBm. It is concluded that with such a receiver a 50dB SNR could be provided in a cell having diameter of 10m with a source that emits 181mW/Str. With the same source a useful SNR of 45 dB would be achieved within a cell having a diameter of 15m and threshold would occur at the edge of a 19m diameter cell. The above results are not significantly affected by typical ambient lighting conditions.