A good turn out heard Brian explain the need for a WW2 system to achieve greater accuracy in the Anti-aircraft systems. The equipment needed to track a moving aircraft was complicated by the typical shell time of ten to twenty seconds and the need to predict the movement of the target.
By 1940 various systems such as photo sensors, electrostatic or magnetic field sensors were tried buy found wanting. Fortunately, Three British men, Butement, Shire and Thomson of The Air Defence Experimental Establishment suggested a CW oscillator in the shell with a circuit that would measure the Doppler effect of a reflected signal from the target and trigger the explosive shell.
However, Britain did not have the resources to produce the fuze in sufficient numbers and the decision was taken to send the design to the USA as part of the ‘Tizard Mission’ since the USA had the industrial resources to exploit the military potential of the British research.
The system was used with very little modification and in combination with the SCR 584 ten centimetre tracking radar was considered the most important development in WW2 after the Atom Bomb.