Multi-Channel Pressure Telemetry System for Base Pressure Measurements on Small Models.

摘要

Effects of close proximity on simultaneously operating transducer-telemtry units had been systematically evaluated. Parameters such as the interaction as function of transducer-to-transducer distances, center frequency spread and its effect on the interaction, change of sensitivity in relation to center frequency, center frequency shifts as functions of transducer-to-transducer distances, and the effects of common power supply and shielding have been evaluated. The results showed that the interaction increases approximately as the inverse square of the distance. The center frequency spread has the most significant effect on the interaction. If 7MHZ or larger frequency spacing is maintained the maximum error is plus or minus 8 percent for the pressure range of 0.5 to 2.0 mm Hg. The measured data can be corrected by an interaction matrix method and yield errors in the order of a few percent depending on the accuracy of calibration.