Research/Patents/US 4842247
US 4842247

METHOD AND APPARATUS FOR THE DETECTION OF HELICOPTERS

Assignee

CARL-ZEISS-STIFTUNG, HEIDENHEIM/BRENZ, DBA CARL ZEISS

Filed

Sep 14, 1978

Granted

Jun 27, 1989

Location

DE

Abstract

The presence of an operating helicopter within a given field of view is remotely and passively monitored by optically imaging the field of view at a focal surface, using an infrared detector to produce an electrical signal. The electrical signal is filtered with a narrow pass-band having a center frequency which is adjustable over a range which spans the respective modulation frequencies of characteristic infrared radiation emitted by the rotating blades of each of a plurality of helicopters of different type. Provision is made to indicate such component of the electrical signal as survives the filtering step.

Source: Google Patents

35 USC §181 Secrecy Order

Imposed

Jun 2, 1983

Rescinded

Jul 30, 1986

Duration

3 years, 1 month

Inventor

  • 1GUNTHER KURBITZ

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Back to patent indexSource: USPTO 35 USC §181 secrecy order records