Doppler radar system

Claim 1

A DOPPLE RADAR SYSTEM COMPRISING: (A) A FIRST AND A SECOND SOURCE OF ELECTROMAGNETIC WAVE ENERGY, EACH SOURCE OPERATING CONTINUOUSLY TO PRODUCE ENERGY, RESPECTIVELY, AT A FIRST AND A SECOND FREQUENCY; (B) MEANS INCLUDING SWITCHING MEANS COUPLED TO SAID FIRST AND SECOND SOURCES OF ENERGY FOR PERIODICALLY, AND AT MUTUALLY EXCLUSIVE TIMES, TRANSMITTING MICROWAVE ENEGRY FROM THE FIRST AND THE SECOND SOURCE OF ENERGY; (C) MEANS COUPLED TO SAID LAST NAMED MEANS FOR MIXING ECHO SIGNALS RESULTING FROM THE REFLECTION OF MIRCOWAVE ENERGY AT THE FIRST FREQUENCY WITH A PORTION OF THE MICROWAVE ENERGY AT THE SECOND FREQUENCY AND THE ECHO SIGNALS RESULTING FROM THE REFLECTION OF MICROWAVE ENERGY AT THE SECOND FREQUENCY WITH A PORTION OF THE MICROWAVE ENERGY AT THE FIRST FREQUENCY TO PRODUCE A SUBSTANTIALLY CONTINUOUS FIRST SIGNAL HAVING THE DIFFERENCE OF THE FIRST AND THE SECOND FREQUENCY AS A CARRIER; AND, (D) MEANS FOR DERIVING A SUBSTANTIALLY CONTINUOUS SECOND SIGNAL FROM THE SUBSTANTIALLY CONTINUOUS FIRST SIGNAL, THE FREQUENCY OF THE SECOND SIGNAL BEING PROPORTIONAL TO THE DOPPLER SHIFT FREQUENCY IN THE ECHO SIGNALS, (E) SAID SWITCHING MEANS INCLUDING MEANS CONTROLLED BY THE FIRST AND SECOND SOURCE OF ENERGY TO PRODUCE A FIRST AND SECOND SIGNAL; AND MEANS FOR ADJUSTING THE OCCURRENCE OF THE FIRST GATING SIGNAL WITH RESPECT TO THE OUTPUT OF THE FIRST SOURCE OF ENERGY AND THE OCCURRENCE OF THE SECOND GATING SIGNAL WITH RESPECT TO THE OUTPUT OF THE SECOND SOURCE OF ENERGY TO CAUSE THE SWITCHING MEANS TO BE ACTUATED ONLY WHEN THE OUTPUT OF THE FIRST AND THE SECOND SOURCE OF ENERGY ARE AT A MINIMUM.