System for measuring torque and speed of rotating shaft

A detecting system for providing information regarding the torque and speed of a rotatable permeable shaft, comprising:

• a magnetic transducer encompassing the rotatable shaft and including first, second and third magnetic cores, a primary winding wound on said first magnetic core, a first secondary winding wound on said second magnetic core, and a second secondary winding wound on said third magnetic core;
• an energizing signal source for providing an a-c excitation signal having a predetermined frequency very high relative to any torque or speed changes;
• means for supplying said a-c excitation signal to said primary winding to produce a magnetic field, adjacent to the rotatable shaft, which is a function of the rotational speed of the shaft and the torque on the shaft,
• said first secondary winding developing, from the magnetic field, a first modulated excitation signal having phase-opposed torque and speed components, and said second secondary winding developing, from the magnetic field, a second modulated excitation signal having inphase torque and speed components, said first and second modulated excitation signals essentially constituting amplitude modulated suppressed carrier signals;
• means, including adding and subtracting circuits, for combining said first and second modulated excitation signals from said transducer to produce a first suppressed carrier signal whose amplitude is modulated at zero phase by the torque parameter of the rotatable shaft and a second suppressed carrier signal which is amplitude modulated at quadrature phase by the speed parameter of the shaft;
• a first synchronous detector to which is applied the first amplitude modulated suppressed carrier signal;
• a second synchronous detector to which is applied the second amplitude modulated suppressed carrier signal;
• and means for supplying said excitation signal, from said energizing signal source, at zero phase to said first synchronous detector and 90.degree. phase-displaced to said second synchronous detector in order to provide said detectors with the carrier signals required to demodulate the first and second amplitude modulated suppressed signals and produce therefrom separate torque-indicating and speed-indicating signals.