Automatic continous frequency calibration for super-regenerative oscillators used in nuclear quadrupole resonance.
A new and improved method for continuous frequency calibration of the super-regenerative oscillator spectrum is described. The arrangement employs a Hewlett-Packard Model HP5345A reciprocal frequency counter capable of measuring the carrier frequency of rf pulses. The counter gate time is externally controlled via the quench pulses. High-resolution measurements are obtained through the use of the frequency-averaging mode provided by the counter. Three successive digits are displayed on a two-channel recorder using a digital-to-analog converter along with the lock-in output. This method provides automatic and continous high-accuracy frequency calibration of the spectrum which is independent of the rf level, quench frequency, and FM amplitude.
Murgich
J
J
Centro de Quimica, I.V.I.C., Apartado 1827, Caracas, Venezuela.