GPS radiosonde is an Upper-air sounding instrument to measure various types of meteorological data; wind speed, wind direction, pressure, temperature and humidity. Wind speed, wind direction and pressure are calculated from the travel speed and altitude obtained by GPS positioning techniques. Every 1 second measured data are transmitted to ground receiving system via 400-406 MHz band.

Compact and commonly-used devices are aggressively adopted in iMS-100 to achieve downsizing (just only 38 g including one battery) and its cost reduction. iMS-100 also serves for total operation cost saving by using smaller balloon and reducing the gas amount depending on the target height. Furthermore, the lightweight package greatly enhances safety in the sounding operation even without parachute when it accidently falls down on land, especially.

Improved sensor boom achieves higher accuracy in temperature measurement. Also, newly developed high response humidity sensor enables more accurate humidity measurement even in low temperature environment (below –40℃). In addition to the advantages of cost and safety, the innovative downsizing can minimize pendulum motions and heat contamination from the sonde itself during launch, which improves the measurement performances in terms of wind and temperature.