H Heuer Instruments UMDT51A, Руководство пользователя

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Making Measurements
LT51 User Manual 47
Distortion (Numerical measurements)
To display the level, frequency and distortion of the input signal:

press the key and then [f1] to measure Level/Distortion. Select the
desired Distortion function by pressing the appropriate soft-key.
The available distortion functions are:

Total Harmonic Distortion(THD)

Signal to Noise ratio (S/N)

Signal to Noise and Distortion (S/ND)

Spurious Free Dynamic Range (SFR).
To cancel the distortion function and return to displaying just the level and
frequency of the signal, select
Noise .
To view the spectrum display of the distortion, press the key.
See the preceding section on Distortion (Spectrum Measurements) for more
information on each distortion measurement.
If the “AutoRange” setting is LVL+BW, the LT51 will automatically set the
frequency span to 4x the frequency of the fundamental signal (or largest current
input signal).
To make the O.132 Quantising Distortion measurement, setup a 1 kHz tone to
be transmitted through the network, set the Distortion function to S/ND, and if
desired, select the ITU-T O.41 Psophometric filter to weight the measurement.