Signal processing circuit for instantaneous fourier transformation

A signal processing circuit comprising an input means for receiving an input signal, combining means having a plurality of inputs coupled for receiving said input signal from said input means on one of its inputs and for supplying a combined signal, delay means coupled to receive said comdined signal from said combining means for delaying said combined signal for a predetermined time and for providing a delayed signal, power dividing means coupled to receive said delayed signal from said delay means and for supplying an output signal and a feedback signal, output means coupled to said power dividing means coupled for receiving said output signal, first mixing means coupled to said power dividing means for receiving said feedback signal, first local oscillator means coupled to supply a first oscillator signal to said first mixing means, said first mixing means being constructed to supply a first mixed signal comprising said feedback signal and said first oscillator signal, a first zonal filter means coupled to receive said first mixed signal and for supplying a first filtered signal, second mixing means coupled to said first zonal filter for receiving said first filtered signal, second local oscillator means coupled to supply a second oscillator signal to said second mixing means, said second mixing means being constructed to supply a second mixed signal comprising said first filtered signal and said second oscillator signal, second zonal filter means coupled to receive said second mixed signal from said second mixing means and for supplying a second filtered signal and coupling means for coupling said second mixed signal to a second input terminal of said combining means, wherein a frequency difference exists between said first and second oscillator means which is approximately equal to the inverse of the delay time between said input signal and said delayed signal.