Intermodulation distortion test set for independent sideband transmitters

Claim 1

A CIRCUIT ARRANGEMENT FOR THE GENERATION OF TWO SEPARATE SWEEP TONES OF EQUAL AMPLITUDE WHICH COMPRISES: A VARIABLE SWEEP FREQUENCY AUDIO FREQUENCY GENERATOR HAVING A SAWTOOTH SWEEP VOLTAGE GENERATOR AND A VOLTAGE CONTROLLED AUDIO OSCILLATOR A SOURCE OF STABLE REFERENCE FREQUENCY HIGHER THAN THE FREQUENCY OF SAID AUDIO GENERATOR A FIRST BALANCED MODULATOR HAVING CONNECTED TO ITS INPUTS THE OUTPUTS OF SAID AUDIO GENERATOR AND SAID STABLE SOURCE A FIRST UPPER SIDEBAND FILTER CONNECTED TO RECEIVE THE OUTPUT OF SAID FIRST MODULATOR FOR PASSING ONLY THE UPPER SIDEBAND FREQUENCIES THEREOF, FREQUENCY MEANS FOR PROVIDING A SIGNAL AT A FREQUENCY WITHIN THE SWEEP RANGE OF SAID AUDIO GENERATOR, A DOUBLE BALANCED MODULATOR HAVING CONNECTED TO ONE OF ITS INPUTS THE OUTPUT OF SAID AUDIO GENERATOR CONNECTING MEANS FOR MOMENTARILY CONNECTING THE OUTPUT OF SAID FREQUENCY MEANS TO ANOTHER INPUT OF SAID DOUBLE BALANCED MODULATOR A BANDPASS FILTER CONNECTED TO THE OUTPUT OF SAID DOUBLE BALANCED MODULATOR FOR PASSING ONLY THE STATIC SUM FREQUENCIES AT THE OUTPUT THEREOF, A SECOND BALANCED MODULATOR HAVING CONNECTED TO ITS INPUTS THE OUTPUT OF SAID BANDPASS FILTER AND SAID SOURCE OF REFERENCE FREQUENCY, A SECOND UPPER SIDEBAND FILTER CONNECTED TO PASS THERETHROUGH ONLY THE SUM FREQUENCY OUPTUT OF SAID SECOND BALANCED MODULATOR, A THIRD BALANCED MODULATOR HAVING CONNECTED TO ITS INPUTS THE OUTPUTS OF SAID FIRST AND SECOND UPPER SIDEBAND FILTERS,