Measurements on CW Signals R&S FSH3
Harmonic Measurements
As a Spectrum Analyzer can resolve different signals in the frequency domain, it is ideal for measuring
harmonic levels or harmonic ratios. To speed up these procedures, the R&S FSH3 has marker
functions that deliver fast results with only a few keystrokes.
As above, a signal generator with a 100 MHz output frequency and an output level of –20 dBm is used
in the following measurement example.
First, the R&S FSH3 is set to its default settings to show all measurement steps that are needed.
¾ Press the PRESET key.
The analyzer displays the frequency spectrum from 100 kHz to 3 GHz, the largest available span. At
100 MHz, the generator signal is displayed as a line. The generator harmonics are displayed as lines
at frequencies which are integral multiples of 100 MHz.
To measure the 2nd harmonic ratio, set the Start and Stop Frequency as follows:
¾ Press the FREQ key.
The softkey menu opens for frequency entry.
¾ Press the START softkey.
¾ Enter '50' using the numeric keypad and confirm the entry with the MHz key.
¾ Press the STOP softkey.
¾ Enter '250' using the numeric keypad and confirm the entry with the MHz key.
The R&S FSH3 now displays the spectrum from 50 MHz to 250 MHz, and so the signal at 100 MHz and
its 2nd harmonic at 200 MHz.
To measure the harmonic ratio, set the marker on the fundamental and the delta marker on the 2nd
harmonic.
¾ Press the MARKER key.
The softkey menu opens for marker entry and
automatically positions the main marker on the trace
maximum.
¾ Press the DELTA softkey.
The delta marker is activated (vertical dotted line) and
is automatically placed on the next trace maximum (=
2nd harmonic).
The harmonic ratio can be read off directly in dB from
the numeric delta-marker display.
1145.5973.12 2.4 E-6
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