Rohde & Schwarz Scope Rider RTH1004 - Page 132

Spectrum Analysis
R&S
®
Scope Rider RTH
132User Manual 1326.1578.02 ─ 12
The harmonics measurement performs an FFT on the input signal and determines the
power levels measured at the specified fundamental frequency and at each harmonic.
Harmonics are frequencies that are a multiple of the fundamental frequency.
As a result, the magnitude, frequency and phase values for the selected harmonics are
shown, as well as the RMS power values and the total harmonic distortion (THD).
In general, every signal contains harmonics. Harmonics are generated by nonlinear
characteristics, which add frequencies to a pure sine wave. Harmonics are particularly
critical regarding high-power transmitters such as transceivers because large harmon-
ics can interfere with other radio services.
Harmonic distortion can be determined as the level of the individual components, or as
the root mean square of all components together, the total harmonic distortion (THD).
The THD is set in relation to the power of the fundamental frequency.
6.3.1 Accessing the Harmonic Mode
1. Press the [MODE] key.
2. Select "Harmonic".
An FFT is performed on the input signal, and the power level at the fundamental
and all harmonic frequencies of the signal (that is: all multiples of the fundamental
frequency) are analyzed.
6.3.2 Harmonic Measurement Results and Display
As the result of a harmonic measurement, a bargraph is displayed, with one bar for
each of 64 possible harmonic frequencies. The amplitudes determined for each har-
monic are indicated by a colored bar. The results for each active input channel are dis-
played in a different color. The values are scaled in dB or percent, in relation to the
level at the fundamental frequency. If a limit is defined, either manually or predefined
by a standard, the limit is indicated by a blue horizontal line for each harmonic. If the
measured value exceeds the limit, the background is highlighted red. The darker col-
ored bar indicates the maximum value measured for the harmonic.
Harmonics Measurement (Option R&S
RTH-K34)