Post Processing IQC5000 Recorded Data
66
Listed in the following sections are further descriptions of notable header parameters:
acq_scale_factor
The acquisition scale factor is the floating point number that must be mult
iplied with each I and Q two byte signed
integer sample to convert that sample back to the voltage measured on the signal analyzer. Knowing the actual
voltage level of the signal is critical when making accurate measurements, and when playing back that signal.
In RSA recordings, a 32-bit I and Q representation of that floating po
i
nt number is parsed from the RSA. So for use
with the IQC, the scale factor must be adjusted by 2^16 because the calculation is based on separate I or Q values.
Converting a Recorded Sample to Voltage
To convert a recorded I or Q sample to voltage:
Where:
Ivoltage, Qvoltage = the
voltage level for the I or Q sample
Isample, Qsample =
the 16-bit sample I or Q value
SCF = the 32-bit scale factor
Conv
erting a Recording to Power (dBm)
Once the I and Q voltages are known, the samples can be converte
d
to power in dBm:
Pdbm 20
Ivoltage
2
Qvoltage
2
+
0.22360679 2
--------------------------------------------------------------
log=
Where:
PdBm = power in dBm
Iv
oltage, Qvoltage = the
voltage level for the I or Q sample
Converting a Recording to Power (dB)
Once the I and Q voltages are known, the samples can be converte
d
to power in dB:
Pdb 20log Ivoltage
2
Qvoltage
2
+=
Where:
PdB = power in dB
Iv
oltage, Qvoltage = the
voltage level for the I or Q sample
marker_files
The element marker_files will only hav
e a sub-element marker when markers have been recorded – otherwise,
there will be no marker sub-element.
Ivoltage Isample SCF 65536=
Qvoltage Qsample SCF 65536=
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