| 摘要 |
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.
|
