Brittannica defines telemetry as highly automated communications process by which measurements are made and other data collected at remote or inaccessible points and transmitted to receiving equipment for monitoring. The original telemetry systems were termed supervisory because they were used to monitor electric power distribution. In the first such system, installed in Chicago in 1912, telephone lines were used for transmitting data on the operation of a number of electric power plants to a central office. Since then telemetry has spread to other fields each making improvements and modifications to suit the desired purpose.

Since telemetry is a term used to describe a general process that can involve many different technologies, several inventors could be named in the complex development of telemetry.

Aerospace telemetry started in the 1930s with the radiosonde, a device that automatically measured temperature, barometric pressure and humidity from a ballon high in space, and sent the data back to Earth using a radio signal. Aerospace telemetry for rockets and satellites began on the Soviet satellite Sputnik, launched in 1957. The technology developed in aerospace telemetry has crossed over to many industrial operations; i.e. the testing of internal-combustion engines, watching steam turbines in operation or conveyor belts inside mass-production ovens.

In 1960, the interrogation-reply principle was developed. This is a highly automated arrangement in which the transmitter at the measuring location automatically transmits needed data only after being signalled. The interrogation-reply principle is now used in such fields as oil-pipeline monitor-control systems and oceanography.

History of the DSN
The forerunner of the DSN was established in January, 1958, when JPL, then under contract to the U.S. Army, deployed portable radio tracking stations in Nigeria, Singapore, and California to receive telemetry and plot the orbit of the Army-launched Explorer 1, the first successful U.S. satellite.

Telemetry
Special applications and techniques.

Hildreth "Hal" Walker
Hildreth "Hal" Walker invented laser telemetry and targeting systems.

Wireless Telemetry
Wireless Telemetry, from your About Guide to Wireless Communications