Research/Patents/US 4719606
US 4719606

PROCESS AND DEVICE FOR PASSIVE DETECTION OF AIRCRAFT, NAMELY HELICOPTERS

Assignee

ETAT FRANCAIS AS REPRESENTED BY DELEGUE GENERAL POUR L'ARMEMENT

Filed

Mar 14, 1985

Granted

Jan 12, 1988

Location

PARIS FR

Abstract

A process and device for passive detection of helicopters includes detection of helicopter noise and ambient noise by means of an electro-acoustic transducer, and outputting of an amplitude modulated signal therefrom; amplitude demodulation of the signal in the frequency band between 300 Hz and 3500 Hz; spectral analysis of the demodulated signal; and selection and registration of characteristic frequency lines reflective of the rotary units of the helicopter. The process and device permit passive detection of helicopters in the lower noise, higher frequency band, thereby also permitting utilization of smaller antenna arrays.

Source: Google Patents

35 USC §181 Secrecy Order

Imposed

Mar 31, 1986

Rescinded

Apr 15, 1987

Duration

1 year

Inventor

  • 1MICHEL B. ANDRIEU

Technology Domains

Click a domain to browse all patents in this category.

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