Rohde & Schwarz SMBV100A - LEVEL OFFS: Rmsoffset_Db,Peakoffset_Db

Remote Control Commands
R&S
®
SMBV100A
517Operating Manual 1176.8016.02 ─ 17
To maintain marker signals and waveform data synchronized, set the CONTROL
LENGTH to be equal to the number of samples specified with the tag SAMPLES.
See also Chapter 7.4.2, "How to Define Periodically Repeating Traces",
on page 524.
Example:
{CONTROL LENGTH: 500}
SOURce:BB:ARBitary:CLISt:TAG? 'CONTROL LENGTH'
Queries the length of the control list.
Response: 500
{LEVEL OFFS: RMSOffset_dB,PeakOffset_dB}
(recommended for waveforms)
The tag determines the level of the ARB signal in the waveform file. The offset levels
define the offset of RMS and peak value relative to the 16-bit full scale modulation
(-32767 to + 32767) = 0 dB.
Setting parameters:
RMSOffset_dB Defines the RMS level offset of the signal relative to full scale
ARB signal in the WAVEFORM tag. The offset is defined in ASCII
float format. The value is always positive.
A 3 dB value indicates that the RMS level of the signal is 3 dBs
below the full scale.
full scale = max. amplitude of vector of I/Q samples = |S
IQ
|max =
sqrt(I
2
+Q
2
)max = 0 dB
PeakOffset_dB Defines the peak level offset of the signal relative to full scale for
the ARB signal in the WAVEFORM tag. The offset is defined in
ASCII float format.
The value usually equals 0 dB as usually the I/Q samples
(signed 16-bit integer values) are modulated to full scale: Full
scale = 0 dB = max. amplitude of vector of I/Q samples = |S
IQ
|
max = sqrt(I
2
+Q
2
)max = (2
15
)-1 = 32767.
A positive PeakOffset_dB value indicates that a headroom to
full scale is provided when generating the waveform. A negative
PeakOffset_dB value indicates that overrange is likely for some
samples, i.e. clipping might occur.
The crest factor can be calculated from the two values as fol-
lows:
Crest Factor = |PeakOffset_dB - RMSOffset_dB|
Example:
{LEVEL OFFS: 3.45,2}
BB:ARB:WAV:TAG? 'LEVEL OFFS'
Queries the content of the LEVEL OFFS tag of the selected
waveform file.
Response: 3.45,2
The level of the waveform is below full scale, clipping does not
occur.
Usage: Setting only
Waveform and List Format