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NI PXIe-5601 Calibration Procedure
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© National Instruments
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21. Configure the NI PXI/PXIe-5652 frequency to the
NI 5652 LO Frequency
shown in
Table 23 or 24, corresponding to the module revision of your NI 5601. Use the niRFSG
Frequency property or the
NIRFSG_ATTR_FREQUENCY
attribute.
22. Set the
RF Source Power
, in dBm, using the following formula and the IF1 and IF2
attenuation values as found in step 16:
RF Source Power = (IF1 Atten IF2 Attenuation) -
36
23. Use the appropriate frequency for the channel A sensor.
24. Wait 750 ms or until power sensor A settles to 0.1% of the source power, whichever is
greater.
25. Read the channel A power. Calculate the
RF Power
using the following formula.
Calculation of the
RF Input Calibration Factor
may require linear interpolation.
RF Power = Channel A Power + RF Input Calibration Factor
26. Measure the output power using the spectrum analyzer. This value is the
IF Power
.
Note
To reduce the amount of noise in the spectrum analyzer measurement without
sacrificing test time, NI recommends using the following adaptive averaging
methodology at each measurement point:
1. Take a measurement with the spectrum analyzer set to zero span. If your analyzer
does not support zero span, use a span of 10 Hz.
2. Based on this first measurement, reconfigure the spectrum analyzer as shown in
Table 26 and take another reading to obtain the final measurement value. Span is
always set to either zero span or 10 Hz.
27. Calculate
Gain
using the following formula:
Gain
=
IF Power
-
RF Power
28. Repeat steps 20 to 27 for all the LO frequencies for the corresponding
IF Filter
in Table 23
or 24, depending on the module revision of your NI 5601. Store the gain values computed
in step 27 in an array. You can repeat steps 19 through 27 with the first spectrum analyzer
measurement at a reference level similar to the second measurement. This repetition
reduces internal attenuator switching. The second measurement must follow the settings in
Table 26.
Table 26.
Spectrum Analyzer Settings
First
Measurement
Reference
Level
Resolution
Bandwidth
Samples
to Average
-10 dBm
20 dBm
100 Hz
5
<-10 dBm, -40 dBm
0 dBm
200 Hz
10
<-40 dBm
0 dBm
200 Hz
20