Similar Systems
Interestingly, the Germans improvised a system conceptually similar to Oboe, code named Egon, to perform bombing on the Eastern Front on a limited scale. It used two modified Freyas to play the roles of Cat and Mouse; these two Freya Egon sets were located about 150 km apart, and the aircraft carried a two channel IFF to respond to them. Voice radio directed the bombers. Despite the considerable effort the Germans put into other electronic navigation systems, they never took this concept farther.
Along with the range restriction, Oboe had another limitation: it could only really be used by one aircraft at a time. As a result, the British rethought Oboe, and came up with a new scheme named "GEE-H" (or "G-H") based on exactly the same thinking, differing only in having the aircraft carry the transmitter and fitting ground stations with the transponder.
Multiple aircraft could use the two stations in parallel because random noise was inserted into the timing of each aircraft's pulse output. The receiving gear on the aircraft could match its own unique pulse pattern with that sent back by the transponder. Each receive-reply cycle took the transponder 100 microseconds, allowing it to handle a maximum of 10,000 interrogations per second and making "collisions" unlikely. The practical limit was about 80 aircraft at one time.
The name "GEE-H" is confusing, since the scheme was very close to Oboe and not very much like GEE. The name was adopted because the system was based on GEE technologies, operating on the same range of 15 to 3.5 meters / 20 to 85 MHz, and initially used the GEE display and calibrator. The "H" suffix came from the system using the twin-range or 'H' principle of measuring the range from transponders at two ground stations. It was about as accurate as Oboe.
Read more about this topic: Oboe (navigation)
Famous quotes containing the words similar and/or systems:
“A whole village-full of sensuous emotion, scattered abroad all the year long, surged here in a focus for an hour. The forty hearts of those waving couples were beating as they had not done since, twelve months before, they had come together in similar jollity. For the time Paganism was revived in their hearts, the pride of life was all in all, and they adored none other than themselves.”
—Thomas Hardy (1840–1928)
“The geometry of landscape and situation seems to create its own systems of time, the sense of a dynamic element which is cinematising the events of the canvas, translating a posture or ceremony into dynamic terms. The greatest movie of the 20th century is the Mona Lisa, just as the greatest novel is Gray’s Anatomy.”
—J.G. (James Graham)