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HEWLETT-PACKARD
JOURNAL
T E C H N I C A L I N F O R M A T I O N F R O M T H E - d p - L A B O R A T O R I E S
Vol. 15, No. 8
PUBLISHED BY THE HEWLETT-PACKARD COMPANY, 1501 PAGE MILL ROAD, PALO ALTO, CALIFORNIA APRIL, 1964
A New Instrument for Measuring
Microwave Frequencies with Counter Accuracy
JU OR SEVERAL years now, it has been possible to mea monies zero-beats with the unknown microwave signal
sure VHF Signals accurately with electronic counters. and the VHF oscillator frequency is measured with the
These measurements are made by converting a high counter. The frequency of the unknown signal then is
frequency to a related lower frequency, generally by calculated after determining which harmonic causes
heterodyning the measured signal with a harmonic of the zero-beat. This technique enables measurements
the counter's time base oscillator to derive a suitable of frequencies up to 40 Gc with an accuracy approach
difference frequency1. ing 1 part in 107.
For measurements of higher frequencies, a transfer More recently, significantly better accuracies have
oscillator customarily is used with a counter^. The been obtained by using a synchronizer with the transfer
VHF transfer oscillator is tuned until one of its har- oscillator3. The synchronizer slaves the transfer oscil
lator to a sub-multiple of the unknown signal with
1 "A New Frequency Counter Plug-In Unit for Direct Frequency
Measurements to 510 Me;1 Hewlett-Packard Journal, Vol. 12, No.
5, January, 1961. ! Albert Benjaminson, "An Instrument for Automatically Measur
! Dexter Hartke, "A Simple Precision System for Measuring CW ing Frequencies from 200 Me to 12.4 Gc" Hewlett-Packard Jour
and Pulsed Frequencies up to 12,400 Mc|' Hewlett-Packard Jour nal, Vol. 13, No. 3-4, Nov.-Dec., 1961.
nal, Vol. 6, No. 12, August, 1955.
SEE ALSO:
DC-8 Gc 'scope plug-in, p. 5
New WWV/WWVH time information, p. 8
Cresf factor, p. 8
TIME *