Alec Reeves initially refused to work on weapons, but after he needed to escape from the Nazis when they occupied Paris, he agreed to work on radar. He developed the OBOE (Objective Bombing Of Enemy - see note below) radar system which enabled ground control of the release of bombs with high accuracy. It was used against V1 launch sites and in the Normandy landings. His war work earned him the OBE.

Oboe worked by flying the aircraft at constant range from a transmitter, along an arc. Pulse timing was used to measure the range with great accuracy. A second station created another arc of constant range and the values of the two ranges were set so that where the two intersected was a short distance from the actual target. When the bombs were released, they followed a tangential course rather than continue along the arc. An allowance was been made for this, and the bombs landed on their targets to within a few metres.

Map from http://www.multimap.com

Alec Reeves based his idea on the fact that he could measure range far more accurately than he could measure bearings. There was no beam that the enemy could pick up and predict the course of the aircraft. However it did have the disadvantage that the aircraft had to transmit a short pulse in order for it and the base station to determine its range and also that the traffic handling of the system was very limited.

The great advantage was that the decision to release the bombs was made by an officer at a base station well away from the heat of battle, hence the acronym Objective Bombing Of Enemy. There is a story going around that when the pilot was flying along the correct arc the equipment made a sound like an oboe to show that he was on course, the note changed if he went off course. Given this description of Oboe, this may be a confusion from some other system. If anyone knows the truth of the matter, please post an article to the discussion group.

The transmission problem was solved by using a frequency too high for the limitations of the enemy technology, and the traffic handling problem was solved by using Oboe only for marker flares to be dropped for a following bomber fleet. However in the early stages of development, some officials gave too much weight to the disadvantages and this resulted in personal attacks on the integrity and ability of the people proposing it.

As things turned out, however, Oboe was the most accurate bombing system used in the war.

Note 1. The acronym idea came from The Power of Speech a book about ITT and STC by Peter Young. It seems an apt acronym, but the "sound of an oboe" could have been appropriate also. Two TRE men said the name definitely derived from the sound. The similarity with the musical instrument had been noticed by a TRE engineer called Tony Bates who took part in the early test flights. They both added that acronyms were never used as system names until the Americans got more closely involved, and 'Oboe' never stood for anything but itself.
UK readers: click here.
Buyers in Rest of the World

Further Reading

Oboe (scroll down)
Wikipedia on Oboe

Most Secret War by R.V. Jones
UK/European buyers
Buyers in Rest of the World

Reeves, A.H. and J.E.N. Hooper. Oboe: history and development. in IEE Proceedings, Vol. 132, Pt. A, No. 6, October, pp. 394-8

Channel 4 (in the U.K.) broadcast a film by David Robertson about the OBOE blind bombing system on Sunday, 3 March, at 8 pm. It was called Birth of the Smart Bomber and was in the Secrets of the Dead strand [series]. It is not known if it will be shown in the US. Click here for full details