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 Duplex (Latin, 'double') may refer to: Arts and entertainment * ''Duplex'' (film), or ''Our House'', a 2003 American black comedy film * Duplex (band), a Dutch electronic music duo * Duplex (Norwegian duo) * Duplex!, a Canadian children's music ...

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 (messa ...

system developed during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

for use by

Special Operations Executive The Special Operations Executive (SOE) was a secret British World War II organisation. It was officially formed on 22 July 1940 under Minister of Economic Warfare Hugh Dalton, from the amalgamation of three existing secret organisations. Its pu ...

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 or R SIGS) is one of the combat support arms of the British Army. Signals units are among the first into action, providing the battlefield commun ...

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, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

. 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 to him. 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, {{ISBN, 1-898805-08-3 Use of the phone is shown in the post-war docu-drama ''

Now It Can Be Told "Now It Can Be Told" is a popular song written by Irving Berlin for the 1938 film '' Alexander's Ragtime Band'', where it was introduced by Alice Faye and Don Ameche. It was nominated for an Academy Award in 1938 but lost out to "Thanks for the ...

'' (aka

School_for_Danger ''School for Danger'' (also known as ''Now It Can Be Told'') is a 1947 British docudrama film directed by Teddy Baird depicting the training and deployment of agents of the Special Operations Executive during the Second World War. The film stars ...

, 1946) o
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Specifications

General

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

Notes

British military radio World War II British electronics Military radio systems

Description

See also

Specifications

General

Notes