Fourier transform signal generator

Claim 1

APPARATUS FOR CONVERTING A REPRODUCIBLE, VARIABLEAMPLITUDE ELECTRICAL SIGNAL INTO A SIGNAL HAVING AN AMPLITUDE INDICATIVE OF THE AMPLITUDE OF THE FREQUENCY COMPONENTS OF THE VARIABLE-AMPLITUDE ELECTRICAL SIGNAL, COMPRISING: FIRST MEANS HAVING A CONTROL CIRCUIT AND FIRST AND SECOND OUTPUT CIRCUITS, FOR PRODUCING FOR A PREDETERMINED TIME INTERVAL A SINUSOIDAL ELECTRICAL SIGNAL OF CONSTANT FREQUENCY IN SAID FIRST OUTPUT CIRCUIT AND A COSINUSOIDAL CONSTANT AMPLITUDE ELECTRICAL SIGNAL OF THE SAME FREQUENCY IN SAID SECOND OUTPUT CIRCUIT RESPONSIVE TO AN ELECTRICAL STARTING SIGNAL APPLIED TO SAID CONTROL CIRCUIT; FIRST ELECTRICAL CIRCUIT MEANS ELECTRICALLY COUPLED TO SAID FIRST OUTPUT CIRCUIT, FOR ELECTRICALLY MULTIPLYING THE OUTPUT SIGNAL FROM SAID FIRST OUTPUT CIRCUIT WITH SAID VARIABLE-AMPLITUDE ELECTRICAL SIGNAL, AND FOR INTEGRATING THE RESULTING SIGNAL; SECOND ELECTRICAL CIRCUIT MEANS ELECTRICALLY COUPLED TO SAID SECOND OUTPUT CIRCUIT, FOR ELECTRICALLY MULTIPLYING THE OUTPUT SIGNAL FROM SAID SECOND OUTPUT CIRCUIT WITH SAID VARIABLE-AMPLITUDE ELECTRICAL SIGNAL, AND FOR INTEGRATING THE RESULTING SIGNAL; AND MEANS CONNECTED TO SAID FIRST ELECTRICAL CIRCUIT MEANS AND TO SAID SECOND ELECTRICAL CIRCUIT MEANS, FOR DERIVING A SIGNAL INDICATIVE OF THE SQUARE ROOT OF THE SUM OF THE SQUARES OF THE OUTPUT SIGNALS OF SAID FIRST AND SECOND ELECTRICAL CIRCUIT MEANS.