Abstract: A self regulating telephone apparatus wherein an individual's speech is converted to a representative electrical signal. This signal is represented by a product wave or waves of the form f(A)t x f(B)t where f(A)t represents the amplitude of the informational signal f(B)t. The signal is separated by demodulation of the cross product into its components. The relative amplitudes of the terms are changed as desired and the cross product re-established by remodulation. Since the term f(A)t represents the amplitude and its frequency range is removed from f(B)t, amplification can be provided at frequencies exhibiting low coupling between the receiver and transmitter transducer in a hand telephone set to permit increasing the signal volume output as required.

Abstract: A four-wire interface regulator for long distance trunk circuits is provided in which the interface regulator separates the components of a conventional local plant output signal to change the relative magnitude of the components to deliver any desired output with a minimum variability to drive long distance trunk circuits.