The Mini-Refractionsonde System (MRS) for Meteorological and Refractivity Measurement

The Navy has a requirement to measure the vertical profile of index-of-refraction from sea level to above 20,000 feet. To fill this need, the Mini-Refractionsonde System (MRS) is under development by Honeywell Inc. under contract from Naval Air Development Center and sponsored by Naval Air Systems Command (AIR-370). The Mini sonde weighs only 130 grams. It measures temperature with a rod thermistor to ± 0.5°C, humidity with a hygristor to 5% and pressure with a miniature silicon diaphram barometer to 1.5mB. Winds are measured without tracking by using the OMEGA radio navigation system. Electronics time-commutates the sensors every 400 milliseconds. A solid-state transmitter provides an output of 1/2 watt at 404 MHz. Power for the transmitter and minisonde electronics is provided by a lithium battery. A special telemetry receiver has been developed to receive the meteorological signals in the presence of a high EMI radar environment. A microprocessor based ground station provides on-line real-time data reduction and display.