Wideband frequency modulation systems

Claim 1

A CIRCUIT FOR GENERATING A FREQUENCY MODULATED SIGNAL HAVING UPPER MODULATING FREQUENCIES APPROACHING THE MAGNITUDE OF THE CARRIER FREQUENCY COMPRISING: FIRST AND SECOND OSCILLATOR CIRCUITS, EACH OF SAID OSCILLATOR CIRCUITS INCLUDING A TRANSISTOR HAVING BASE, EMITTER TERMINALS; AN INDUCTOR ARRANGED BETWEEN SAID EMITTER AND BASE TERMINALS; MEANS FOR PROVIDING A VARIABLE CAPACITANCE IN PARALLEL WITH SAID INDUCTOR; AND OUTPUT MEANS CONNECTED TO THE COLLECTOR TERMINALS OF EACH OF SAID TRANSISTORS, THE VALUES OF THE COMPONENTS OF THE OSCILLATORS BEING SUCH AS TO ESTABLISH FIRST AND SECOND SPACED NOMINAL FREQUENCIES; SUBSTANTIALLY HIGHER THAN THE UPPER MODULATING FREQUENCIES; MEANS FOR PROVIDING AN INPUT SIGNAL TO VARY COINCIDENTLY THE CAPACITANCE OF EACH OF SAID OSCILLATORS, SUBSTANTIALLY EQUALLY BUT IN OPPOSITE SENSES; AND MEANS FOR HETERODYNING THE SIGNALS APPEARING AT THE OUTPUT MEANS OF THE TRANSISTORS TO DERIVE A FREQUENCY MODULATED OUTPUT SIGNALS AT A CARRIER FREQUENCY EQUAL TO THE FREQUENCY DIFFERENCE BETWEEN SAID GENERATED SIGNALS, SAID FIRST AND SECOND NOMINAL FREQUENCIES BEING SPACED APART BY A FREQUENCY SLIGHTLY EXCEEDING THE UPPER MODULATING FREQUENCIES.