United States of America As Represented by the Secretary of the Air Force

John W Lunden

Ying C Hwang

A sensitive and precise detector is described for application in determining the 'Centroid' of the video pulse of a radar return echo. A tunnel diode, connected and biased in a balanced configuration with respect to ground and selected taps on a signal delay line, is the key element of the circuit. The sum and/or difference of the tapped signals are formed in such a manner that a precise zero crossing, corresponding to the 'centroid' of the pulse, may be determined. The special characteristics of the tunnel diode are utilized to achieve additional objects, base line noise immunity, multiple echo self resetting, and high speed-precision response. The tunnel diode is positioned in relation to four (or more) input signals and ground such that with no signal on the delay line, it is biased - at a stable low-current-high-voltage state. An incoming signal causes a series of state changes designed to 'switch' the diode to a second state at the time of zero crossing, resulting in the occurrence of a voltage step which, in turn, causes the differential amplifier connected to the tunnel diode to also change state - with amplification.

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Camillus, NY, United States of America

John W Lunden