Digital channelized IFM receiver

A digital channelized IFM (Instantaneous Frequency Measurement) receiver comprising first means for receiving RF input signals from antenna means and for converting the RF input signals to IF signals, analog-to-digital conversion means coupled to the first means for converting the IF signals to digital signals at D data points, the analog-to-digital conversion means being coupled to digital filter bank means for providing channelized digital signals using a P point short FFT (Fast Fourier Transform) to perform the channelization to provide i=1 to P/2 channels, digital IFM receiver means for processing the channelized digital signals to effectively provide digital IFM receiver means for the output of each channel;

• wherein the short FFT is overlapped P-1 points, and the output of each channel is written as I.sub.i (t.sub.j) and Q.sub.i (t.sub.j) where I and Q are inphase and quadrature components of a complex form, i represents output channel number, and j=1 to (D-P+1) represents the output time, and the means for finding a phase .THETA..sub.i of each output signal as ##EQU5## means for finding the phase difference of each channel as
• .delta..THETA..sub.i (t.sub.j)=.THETA..sub.i (t.sub.j+1)-.THETA..sub.i (t.sub.j)
• and means for finding the frequency of the output signal from ##EQU6## wherein the frequencies of all channels are measured, if the frequency measured by an IFM receiver matches the center of a channel, that channel contains a signal, and if the frequency measured by the IFM receiver does not match the center of the channel, that channel does not contain a signal, so that using this measurement, the channels containing signals can be identified.