- S-Phone
The S-Phone system was an
ultra high frequency duplex radio telephone system developed duringWorld War II for use bySOE 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 theRoyal Signals . [cite web
last = Soerensen
first = Lars Peter
authorlink =
coauthors =
title = SOE Radios
work = Clandestine Radios and SOE Equipment 1940 - 1945
publisher =
date =
url = http://lps-radio.rytter.net/soe-radios.htm
format =
doi =
accessdate = 2008-01-23 ]Description
The "Ground" set - which was to be used by agents on the ground - weighed about 15 lbs 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 10,000 ft which brought the aircraft within range of
flak . It permitted direct two-way voice communication with an aircraft up to a range of 30 miles. 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). [cite book
last = Foot
first = Michael Richard Daniell
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title = SOE in France
publisher =Routledge
date = 2004
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pages = p. 80
url =
doi =
id =
isbn = 0714655287 ]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.
pecifications
General
*Frequency: 337 MHz (TX) / 380 MHz (RX)
*Output Power: 0.1 to 0.2 WNotes
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