Measurement of switching characteristics of agile frequency sources

The results of investigations of time-interval averaging and delay-line frequency discriminators are presented and the relative merits of the two techniques are discussed. The former method gives the average frequency in a certain time interval, each interval being averaged over a large number of similar periods to make up the requisite gate time. No information related to frequency, phase modulation, or noise is obtained during this period, nor any measure of the repeatability of each of the periods. An absolute measure of frequency is produced whose accuracy decreases with decreasing frequency. The discriminator technique gives an accurate and instantaneous measure of switching speed and frequency or phase error. However, it is a comparative measurement and does not provide an absolute value for frequency without calibration. It may also present ambiguities in complex switching situations.