SARAH (Search And Rescue And Homing) is an air-sea rescue system. This enhanced extract from the Science section of the May 25, 1953 edition of Time Magazine, summarizes the system operation.
"During the Battle of Britain, when airmen parachuted by the dozens into the choppy waters of the English Channel, the R.A.F. was never quite satisfied with its, search and rescue gear. The keenest eyes and the most sensitive radars often missed the tiny, bobbing targets made by helmeted heads and yellow Mae West jackets.
Last week, more than a dozen years after the R.A.F.'s heroic tangle with the Luftwaffe, Ultra Electric Ltd.. a London television manufacturer, announced that its engineers have finally built a reliable device for finding downed flyers. For more than 200 NATO delegates at the Royal Aircraft Establishment at the Farnborough Air Show,.
Ultra demonstrated SARAH, a tiny (42-oz.) transmitter-receiver which was small enough to be attached to a Mae West.
Downed pilots need only pull a ring to release a coiled, 31-in. antenna, and the little, battery-powered transceiver automatically transmits distress signals on 243 MHz. Pulses are transmitted at a rate of 210 pairs per second with the spacing between the pulses in each pair determined by the coding unit. This allows the beacon signals to be distinguished from each other.
Search planes as high as 10,000 ft. and as far away as 66 miles can pick up the signals on a pair of antennas. Matched like radar pips on the face of a cathode-ray tube, the signal from each antenna is the same height when the plane is headed directly toward the target. Directly over the target, both pips disappear. Then, the downed pilot switches to voice communication for final instructions to his rescuers.
|SARAH implementation by Ultra Electric, UK. Front view. This is the model Type BR1042. The tiny CRT is about 1.5 inches in diameter. Transmit and Receive tuning controls are continuous and not stepped. This equipment is circa 1955.|
|Top rear. The SARAH beacon was normally powered by a combined LT/HT battery. Later versions had a transistorized power supply consisting of a LT battery attached to a transistor inverter.|
|All photos by Chuck McGregor K7MCG|
|This SARAH Mk III receiver was made by Simmonds Precision Products of Tarrytown, NY.The system can locate and identify a downed flyer with a high degree of certantity. (Photo via E-bay)|
This document provides more details on SARAH by referring to the Model SRI 23006. Manual extracts courtesy of Mautritron Technical Services , London UK. Scanned by Chuck McGregor.
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Credits and References:
1) Chuck McGregor K7MCG <cbmcg(at)comcast.net>
2) Time Magazine http://www.time.com/time/magazine/article/0,9171,890595,00.html
3) Wireless For The Warrior http://wftw.nl/gibsongirl/gibsongirl3.html