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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 - h p - L A B O R A T O R I E S
No. 1-2
JBLISHED BY THE HEWLETT-PACKARD COMPANY, 275 PAGE MILL ROAD, PALO ALTO, CALIFORNIA SEPT.-OCT., 1959
A New 20 CPS-50 KG Wave Analyzer
with High Selectivity and Simplified Tuning
In the audio frequency range one of the basic any recurrent electrical phenomena or physi
measuring instruments is the harmonic wave cal phenomena that can be converted into elec
analyzer. In essence, this instrument is a fre trical waves.
quency-selective heterodyne voltmeter which For a wave analyzer to have maximum use
measures the amplitude and frequency of the fulness, it is basically desirable that it have
individual compo high selectivity, but high selectivity by itself
SEE ALSO:
"Measuring Microwave Tube
nents of harmonic or has often been a distinct handicap in actual
Electrode Coefficient complex waveforms. practice. One reason for this has been that the
o f F r e q u e n c y , " p . 5
It is valuable where stability of typical audio frequencies is often
information is needed about the specific har insufficient for the signal to remain within a
monics produced by amplifiers and other trans high-selectivity passband for the time needed
ducers, about the intermodulation products to make a measurement. The user is then forced
generated in multiple frequency systems, about to try to track the signal by hand. Moreover,
the amplitude of voltages in the presence of when a measurement is to be made at a high
noise and the amplitude of voltages too small frequency in the order of kilocycles, tuning a
to be measured by other means, about vibration high-selectivity system to the signal has often
components in mechanical and electrical sys been difficult, because resolution of tuning has
tems, and in general about the components of been inadequate. When such a high-frequency