Rohde & Schwarz R&S UPP, User Manual

Page: 399 / 938

Instrument Functions
R&S
®
UPP
383 User Manual 1411.1055.32 ─ 10
In this way, the frequency response of a transmission link can be precorrected, for
example, and in so doing the measurement point is transformed into another reference
point.
When precorrection is enabled, the computed FFT bins are multiplied by a frequency-
dependent factor, after which they are used to calculate the distortion measurement
and applied to the display.
The factor is determined by interpolation between the two adjacent frequency refer-
ence points in the precorrector table.
Precorrection of the FFT spectrum is an attractive alternative to filtering the input sig-
nal, since the precorrector file can simply be generated from the frequency response
requiring precorrection and need not be in the form of a coefficient file or pole/zero file.
Application:
In acoustic measurements (e.g. with mobile telephones) on artificial ears of type 3.2 or
higher, it is possible to compensate for the transfer function ERP (ear reference point)
to DRP (drum reference point). Measurement of the sound waves by the microphone
applied to the "eardrum" can thus be referred to the required measurement point (at
the auricle).
Note: The precorrector table is created after acquiring or reading in the trace data from
the DUT in the "DispConfig" panels.
"deactivated" The precorrector is disabled. The FFT bins are used and displayed
without change. The measured value is calculated from the
original
FFT spectrum.
"activated" The precorrector is enabled. The next entry field, which is "Equal
File", for the file name of the precorrector table, is activated and the
file shown there is loaded. The measured value is calculated from the
precorrected FFT spectrum.
Remote command:
SENSe[1]:VOLTage:EQUalize
on page 759
MMEMory:LOAD:IEQualize
on page 758
Bargraph
Used for activating bargraph computation and display. In addition the "Bargraph1" win-
dow can be opened from here.
Configuration of the bargraphs is reserved for the "Bargraph1 Config" and/or "Bar-
graph2 Config" windows. The actual display takes place in the "Bargraph1" or "Bar-
graph2" windows.
Note: When measuring total harmonic distortion "(THD+N & SINAD)" there is no point
in having a bargraph display, since the measurement does not involve discrete har-
monics but rather the entire harmonic spectrum complete with noise. Therefore "Bar-
graph" is not available and the graph is not updated.
"deactivated" Bargraph computation (and update) disabled.
Recommended for increasing the measurement speed (e.g. for
sweeps or remote control).
Distortion Measurements