Joan-Eleanor system

From Wikipedia, the free encyclopedia

The Joan-Eleanor system (or J-E for short) was a high frequency radio system developed during World War II for use by agents working behind enemy lines to relay information and replaced the earlier S-Phone system used by agents.[1]

The system was developed from late 1942 onwards for the US Office of Strategic Services (OSS) by DeWitt R. Goddard and Lt. Cmdr. Stephen H. Simpson, with some contributions from inventor and experimenter Al Gross. It was reportedly named for Goddard's wife's Eleanor, and a WAC Major of Simpson's acquaintance named Joan.[1]

The initial design work was performed at RCA's laboratories in Riverhead, NY, and the production units produced by Citizens Radio of Cleveland, Freed Radio Corporation of NYC, Dictagraph Corporation of NYC and Signal-U Manufacturing Company. Most of the testing was carried out at Bovington, England, beginning in July 1944. The first operational use began later that same year.

The system was marked top secret by the U.S. Military and not declassified until 1976.

Contents

[edit] Description

The system comprised a pair of transceivers; a handheld SSTC-502 for use by an agent in the field, and an SSTR-6 transceiver carried by an aircraft flying overhead at a prearranged time. The system was designed to use the UHF band, since it was known that these frequencies could not be effectively monitored by the enemy. The agent made his report in plain speech, and the aircraft recorded the transmission on a wire recorder. Since Morse code was not required, the agent did not need to be trained in it, thus reducing overall training time, which was considered an advantage in the European theater. Additionally, the aircraft could ask for immediate clarification if required, without the delay of encryption and decryption, or an intelligence officer aboard the circling aircraft could talk directly with the agent.

Because of the low power and the unit's limited range, the transmissions were virtually undetectable and the Germans were unaware of the system.

[edit] SSTC-502 transceiver

The hand-held SSTC-502 transceiver used a dual triode as a combination super-regenerative detector while receiving, and an oscillator during transmission. Two other vacuum tubes acted as a microphone amplifier and modulator. The antenna was a simple dipole attached to the top of the unit and the only controls were for regeneration and fine tuning. The unit was powered by two D cells for the tube filaments, and two 67.5 V batteries for the tubes' plates. The original operating frequency was 250 MHz, but it was discovered that the Germans had a receiver capable of operating at this frequency, and it was changed to 260 MHz.

[edit] SSTR-6 transceiver

The airborne SSTR-6 transceiver comprised a superheterodyne receiver with two RF amplifier stages, two limiter stages and an FM detector. Power was supplied by four 6 V wet cell batteries. The equipment was used in B-17 and de Havilland Mosquito aircraft, the Mosquito being used for most missions due to its high speed and high altitude capability which rendered it safe from most defenses.

[edit] Operational

The initial aircraft used with the J-E system were de Havilland Mosquito PR (Photoreconnaissance) Mk. XVI aircraft of the 654th Bombardment Squadron. The missions were codenamed Red Stocking to disguise their nature; useful confusion was created due to weather missions having been codenamed Blue Stocking. For these missions the Mosquitos' bomb-bay was fitted with an oxygen system and modified to accept the SSTR-6 transceiver and wire recorder, with an operator on a cramped drop seat behind the collapsible fuel tank.

The first successful usage of the system was made on 1944-11-22 by Simpson; while orbiting at 30,000 ft over occupied Holland he recorded transmissions from an agent codenamed "Bobbie". The 654th Bombing Squadron flew 32 Red Stocking missions for the OSS over German, Austria and enemy occupied nations. One of the most daring was flown on 1945-03-12 when a Mosquito PR XVI at 30,000 ft over Berlin established radio contact with agents who had earlier been dropped from an A-26 Invader.

[edit] Notes

  1. ^ a b Bowman, Martin W. (1999). Mosquito Photo-Reconnaissance Units of World War 2. Osprey Publishing, p. 62. ISBN 1855328917. 

[edit] References

v • d • e
Radio spectrum

ELF
3 Hz
30 Hz

SLF
30 Hz
300 Hz

ULF
300 Hz
3 kHz

VLF
3 kHz
30 kHz

LF
30 kHz
300 kHz

MF
300 kHz
3 MHz

HF
3 MHz
30 MHz

VHF
30 MHz
300 MHz

UHF
300 MHz
3 GHz

SHF
3 GHz
30 GHz

EHF
30 GHz
300 GHz