Apparatus for suppressing a strong electrical signal

Claim 1

Apparatus for suppressing unwanted strong electromagnetic signals and amplifying weak electromagnetic information signals of substantially the same frequency which comprises: first means for detecting, amplifying and heterodyning all of said electromagnetic signals; said first means comprising circuit means which includes an antenna, radio-frequency amplifier, mixer and oscillator circuits; first amplifier means having a input electrically connected to an output of said first means for simultaneously, non-linearly amplfiying all of said electromagnetic signals from said output of said first means; second amplifier means electrically connected in common to said output of said first means and to an input of said first amplifier means for simultaneously linearly amplifying all of said electromagnetic signals from said output of said first means; gain control means for simultaneously regulating the gain of said first and second amplifier means to control the amplitude of said unwanted strong electromagnetic signals so that the outputs of said first and second amplifier means for said strong signals are equal; subtractor circuit means electrically coupled to the outputs of said first and second amplifier means for subtracting said strong signals of equal amplitude from each other to cause cancellation therebetween, and for subtracting from said weak signals amplified by said first and second amplifier means from each other to produce a resultant output, said output comprising a predominantly linearly amplified information signal; utilization means electrically coupled to said subtractor circuit means for monitoring said resultant output of said subtractor circuit means to adjust said gain control means to maximize the signal strength of said weak information signals thereby isolating said weak signals from said strong signals.