Frequency Measurement by Sliding Harmonics

A method of measuring radio frequencies is described which uses an interpolating, or adjustable, frequency standard. Harmonics of this standard are caused to slide along the frequency scale until the one next below the frequency under measurement is brought up to match that frequency. The number of the used harmonic is readily determined from a simple calibration of the detector, heterodyne frequency meter, or receiver used to receive the frequency being measured. The positive increment in frequency of the used harmonic is determined from the control dial of the adjustable frequency standard. The use of wide-band receivers and interpolating equipment is avoided. Accuracy of measurement of the order of 10 parts per million is realized with the equipment described. If the interpolating frequency standard is treated as a highly stable heterodyne frequency meter, it may be used with many advantages in a conventional frequency-measuring system. The methods discussed are applicable to frequencies up to 1000 Mc.