AI Mark IV radar had two fundamental limitations. First, since it was observer operated, it was unsuitable for single-seat fighters such as the Hurricane and the Spitfire, and secondly, the need for an observer introduced a time lag between the observation of an echo and the initiation of the pursuit. The observer had to determine the direction of the hostile target from the relative amplitudes of the two pairs of echoes and then had to communicate his judgement to the pilot. Mathematical analysis indicated that a ten-second delay in communicating the tube readings to the pilot 'rendered observation useless, and a delay of only two seconds might give serious error. This method eliminated the communication link and therefore reduced the lag in correcting the course which contributed largely to the oscillation phenomena mentioned earlier. It was hoped that with good training and practice the pilot's indicator would allow estimates of 'off-bearing', in elevation and azimuth, to be determined to an accuracy of three to five degrees, and would indicate the range up to 7500 ft. Target selection was achieved by the observer using a strobe pulse and manually tracking the chosen echo.

Inspec keywords: target tracking; mathematical analysis; radar signal processing

Other keywords: communication link; strobe pulse; target selection; mathematical analysis; single-seat fighters; Blitz radar; AI Mark VI radar

Subjects: Radar equipment, systems and applications