Selective voltage or transmission level meter - has two rectifiers each comprising two push-pull modulators, and differential transformer

摘要

In addition to a measurement signal (UM, fM) two carrier signals shifted w.r.t. each other by 90 deg., and at a specified rational frequency relation to the measurement signal, are applied to a first controlled rectifier unit consisting of two push-pull modulators. Output d.c. signals are of the form of UM cos (phi) and UM sin (phi) and are applied together with two further carrier signals U cos (omega)t, and U sin (omega)t, to a second controlled rectifier unit, consisting of two push-pull modulators. It carries out a vectorial addition. A differential transformer is connected to the output of one of the push-pull modulators in the second rectifier, and delivers a signal whose amplitude is proportional to the vector UM.