The S-Phone system was a

UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter ...

duplex

radiotelephone A radiotelephone (or radiophone), abbreviated RT, is a radio communication system for conducting a conversation; radiotelephony means telephony by radio. It is in contrast to ''radiotelegraphy'', which is radio transmission of telegrams (messag ...

system developed during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

for use by

Special Operations Executive Special Operations Executive (SOE) was a British organisation formed in 1940 to conduct espionage, sabotage and reconnaissance in German-occupied Europe and to aid local Resistance during World War II, resistance movements during World War II. ...

agents working behind enemy lines to communicate with friendly aircraft and coordinate landings and the dropping of agents and supplies. The system was composed of a "Ground" transceiver, designed by Captain Bert Lane, and an "Air" transceiver designed by Major Hobday, both of the

Royal Signals The Royal Corps of Signals (often simply known as the Royal Signals – abbreviated to R SIGNALS) is one of the combat support arms of the British Army. Signals units are among the first into action, providing the battlefield communications an ...

Description

The "Ground" set - which was to be used by agents on the ground - weighed about including batteries and was typically worn attached to its operator with two canvas straps. It was a highly directional unit which required the operator to face the path of the aircraft. It had the useful trait that transmitted signals could not be picked up by ground monitoring stations more than one mile distant; however, its signal was only good to , which brought the aircraft within range of

flak Anti-aircraft warfare (AAW) is the counter to aerial warfare and includes "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It encompasses surface-based, subsurface ( submarine-launched), and air-bas ...

. It permitted direct two-way voice communication with an aircraft up to a range of . While the S-Phone provided directional information to the pilot it gave no range information, although a pilot could tell when he was directly over the "Ground" operator because at that point no communication was possible. The primary purpose of the S-Phone was not navigational as such; rather, it was to provide a reasonably secure channel for coded conversation between staff officers based in London and agents in the field, allowing for the exchange of orders and information. The security of a circuit was sometimes tested by using an officer who could recognize whether a voice was actually that of the agent who was supposedly speaking. It was designed in late 1942, using some of the component parts of the Wireless Set No.37.Wireless for the Warrior, Volume 1 Wireless Sets No. 1 - 88, Louis Meulstee, G. C. Arnold Partners 1995, Use of the phone is shown in the post-war docu-drama '' Now It Can Be Told'' (aka School for Danger, 1946) o
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Specifications

General

*Frequency: 337 MHz (TX) / 380 MHz (RX) *Output Power: 0.1 to 0.2 W

Notes

{{reflist British military radio Special Operations Executive Telecommunications in World War II World War II British electronics

Description

See also

Specifications

General

Notes