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Oboe was a British aerial blind bombing targeting system in World War II, based on radio transponder technology. Prior to a mission, a circle was drawn around one of the Oboe transmitters so that it passed over the selected target. The bombers, one at a time, would then attempt to fly along this path towards the target. The Oboe operator in England would use the equipment to see if the bomber strayed from the path and give the pilot instructions on how to regain it. The path was only wide, allowing for much greater accuracy than other systems like Gee. The curved path was quite evident to German radar operators, who came to call the system "Boomerang" after the arc segment left on their displays as the aircraft appeared and disappeared out of range.〔(Web site for the inventor of Oboe, Alec Harley Reeves ). Contains many of his writings and lectures.〕〔(Obituary from The Daily Telegraph of Squadron Leader Harry Scott, specialist navigator who pioneered use of Oboe Navigation )〕 The system was first used in December 1941, about the same time as H2S radar was introduced and a few months after the first use of Gee. As it could only guide one aircraft at a time, Oboe was used to direct the pathfinder bombers to drop their target indicators for the initial stages of the raid; following bombers would use the markers as a reference for conventional bombsights. Individual aircraft were also used to bomb point targets. Gee, a passive system that could be used by an unlimited number of aircraft, remained in use for local guidance over the UK, even after Oboe became widely used for bombing. Oboe's limitation of one aircraft at a time led to several new systems. Among these were the Gee-H system, which used the existing Gee equipment with Oboe-like transmitters. Gee-H could guide about 80 aircraft at once. In the U.S., SHORAN was similar, with a limitation of about 20 aircraft. ==Technical details== Oboe used two stations at well-separated locations in England to transmit a signal to a Mosquito Pathfinder bomber carrying a radio transponder. The transponder re-transmitted the signals, which were then received by the two stations. The round-trip time of each signal gave the distance to the bomber. Each Oboe station used radio ranging to define a circle of specific radius, with the intersection of the two circles pinpointing the target. The Mosquito flew along the circumference of the circle defined by one station, known as the "Cat", and dropped its load (either bombs or marking flares, depending on the mission) when it reached the intersection with the circle defined by another station, known as "Mouse". There was a network of Oboe stations over southern England and any of the stations could be operated as a Cat or a Mouse. The Mark I Oboe was derived from Chain Home Low technology, operating at upper-range VHF frequencies of 1.5 metres / 200 MHz. The two stations emitted a series of pulses at a rate of about 133 per second. The pulse width could be made short or long so it was received by the aircraft as a Morse code dot or dash. The Cat station sent continuous dots if the aircraft was too close and continuous dashes if the aircraft was too far and from these the pilot could make course corrections. (The Germans used a similar method with ''Knickebein''.) Various Morse letters could also be sent, for example to notify an aircrew their Mosquito was within a range of the target. The Mouse station sent five dots and a dash to indicate bomb release. The Mouse station included a bombsight computer, known as "Micestro", to determine the proper release time, there being no particular logic in carrying the bombsight on the Mosquito when it was under the control of the ground station. Although Oboe had been tested against Essen in January 1943, Oboe was rarely used for "big industrial plants" such as those in the Ruhr Area.〔 The basic idea of Oboe came from Alec Reeves of Standard Telephones and Cables Ltd, implemented in a partnership with Frank Jones of the Telecommunications Research Establishment (TRE) and had as part of the team Dr Denis Stops, who later became a leading physicist at the University College London.〔http://www.ucl.ac.uk〕 Denis Stops' role in the development of Oboe was so secret, that he was drafted into the RAF Pathfinder Squadron as a Wing Commander, to conduct his work. His role was largely to develop the systems on the aircraft in conjunction with the land based radar systems. The system worked by using triangulation to pin-point the target. Dr. Stops once said that one unexpected spin off of the system was that the Germans often did not know what the British were planning to bomb. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Oboe (navigation)」の詳細全文を読む スポンサード リンク
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