This baroswitch involves a contact arm connected to the barometer passes over the commutator bar. The contact arm, responding to the pressure changes, moves across the contact points on the commutator bar. Newer model radiosondes use a capacitive transducer with an aneroid capsule. The conducting strip transmits humidity and reference information while the insulator strip transmits temperature information. Each fifth contact is a reference contact.
Variable modulation is used to transmit the collected information.
That is, the radio frequency is changed by the position of the contact arm on the baroswitch. The radio transmitter is located in the pointed plastic cylinder attached to the base of the instrument package. In flight this conical antenna housing is pointed downward. A small battery is contained in the radiosonde package to serve as the power supply for the weather sensing instruments and the radio transmitter. The battery is activated and tested prior to launch.