Sippican Microsonde IIA Teardown

A company called Sippican makes the Microsonde IIA radiosonde. Sippican is owned by Lockheed Martin. Here is a brief description of a radiosonde from the sippican website.

A radiosonde is a meteorological device launched from the ground. The radiosonde measures pressure, temperature, relative humidity, wind speed, and wind direction from the surface to approximately 100,000 feet.

The radiosonde is carried into the upper atmosphere by a balloon, filled with either hydrogen or helium gas. At some point during the ascent the balloon bursts and the radiosonde falls back to the ground, along with the used balloon and parachute (if used).

Throughout the ascent the radiosonde regularly transmits the measurements of atmospheric pressure, temperature, and relative humidity to ground receiving equipment. This ground equipment, called a sounding system, processes and displays the radiosonde data for weather forecasters, then generates meteorological messages that are circulated to the worldwide weather network. Radiosondes can also be equipped with external sensors to measure additional parameters in the atmosphere, such as ozone concentration and radiation levels.

The Microsonde IIA transmits on 1 of 4 channels, this particular one was transmitting a 300 milliwatt FM signal on 1682 MHz that is roughly 180 KHz wide. It records temperature, humidity, pressure and GPS location using a built in GPS receiver. Wind data seems to be derived from the GPS data that is part of the telemetry. GPS and L-Band antennas are built right onto the circuit boards and therefore there is nothing external to the sonde except the temperature probe. The whole sonde weighs just 300 grams including dereeler and train cord.