General Description
R&S
®
CMW-B400B/-B405A
18
User Manual 1176.8116.02 ─ 04
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3.4.1 Single Tone Results
To perform a harmonics measurement, a fixed frequency sine wave audio test tone
(single tone) is transmitted. Harmonics are signals at an integer multiple of the funda-
mental frequency. The n
th
harmonic is n times the frequency of the fundamental wave.
The production of harmonic frequencies by an electronic system is known as harmonic
distortion.
The measured power of the demodulated audio signal has three components:
●
Signal S:
power of the audio signal at the configured reference frequency, see
"Filter > Distortion Frequency"
●
Distortion D:
sum of the signal powers of the 2
nd
, 3
rd
, 4
th
... harmonics
The R&S
CMW measures up to 10 harmonics at frequencies up to 21 kHz.
●
Noise N:
power of the noise floor
The sum of all three components S + N + D is the total received audio power. S and D
can be obtained in frequency-selective measurements. To obtain the sum N + D, the
R&S
CMW uses a notch filter to eliminate the fundamental wave. To avoid suppression
of the higher harmonics, the bandwidth of the notch filter is automatically adjusted to
be smaller than the reference frequency.
Most results of a single tone measurement are calculated from the measured S, N and
D. The following figures show the result tables of an analog measurement and of a dig-
ital measurement.
Fig. 3-6: Analog single tone result table
Measurement Results
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