Pulse-time-modulated radiosonde
From Glossary of Meteorology
pulse-time-modulated radiosonde
(Also called time-interval radiosonde.) A radiosonde that transmits the indications of the meteorological sensing elements in the form of pulses spaced in time.
The meteorological data are evaluated from the intervals between the pulses. The first meteorological telemeter was developed by Olland in 1875 and made use of this principle.