MICROWAVE OPTICAL RECEIVER TECHNIQUES.
Interim engineering rept. no. 1, 1 Jun-31 Aug 65,
SYLVANIA ELECTRONIC SYSTEMS-WEST MOUNTAIN VIEW CALIF ELECTRONIC DEFENSE LABS
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This report presents the results of the first quarter of effort on a one-year applied research program on the use of various techniques for microwave optical communications through the atmosphere. Theoretical considerations of the relative advantages of direct and heterodyne optical receivers, taking into account the vastly increased sensitivity of new phototubes under development in this laboratory, show that heterodyne detection may in many cases by less advantageous than popularly assumed. A qualitative examination of the different possibilities for optical and subcarrier modulation in wideband systems illuminates the system requirements. The use of multimode lasers in such systems is also studied. Experiments have centered on the laboratory optimization of the advanced multiplier phototubes, in order to obtain a consistent, rugged unit for use in the outdoor experiments. A system has been constructed which eliminates the problem of microwave leakage pickup, while avoiding the necessity for screening or shielding techniques. Author