Patent ID: 6437741
Filing Date: 2002-08-20
Classification: G01S

Abstract:
A direction finder apparatus for determining a direction to a device generating a radio frequency (RF) signal that includes an amplitude modulated (AM) component, comprising:an antenna system capable of receiving said signal; a RF front end communicating with said antenna system, said RF front end including at least one filter stage and at least one amplifier stage; an analog signal detector communicating with said RF front end and detecting said electromagnetic signal and providing in response a characteristic signal without an underlying carrier wave; an analog-to-digital (A/D) converter communicating with said analog signal detector and digitizing said characteristic signal; a fast Fourier Transform (FFT) processor communicating with said A/D converter and performing a Fourier transform on said digitized signal over a predetermined sampling period, said FFT processor producing a plurality of component frequency approximations representing frequency components of said AM signal; a plurality of storage bins communicating with said FFT processor and storing said plurality of component frequency approximations; and a post-processor communicating with said plurality of storage bins, said post-processor determining a maximum S/N ratio from among said plurality of component frequency approximations; wherein a direction of arrival (DOA) angle of said RF signal is determined when said antenna system is oriented to produce a maximum S/N ratio.