PXIe-5665 Calibration Procedure
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© National Instruments
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65
11. Set the RF source 2 power to the
RF Source Power LPF
to one of the following values for
the RF source 2 frequency:
•
Preamplifier disabled: 0 dBm
•
Preamplifier enabled: -30 dBm
12. Enable the RF source 2 output.
13. Wait 500 ms before making the first measurement and wait 100 ms before making
subsequent measurements to allow the PXIe-5665 and RF source 2 amplitudes to settle.
Note
Settling times are a characteristic of the RF source device. Refer to the
section of this document for a list of NI-recommended source devices and
device specifications. If you use an RF source device with different device
specifications, your settling times may differ from those listed in this procedure.
14. Measure the power spectrum with the PXIe-5665.
15. Find the highest peak within the measurement bandwidth (BW). This value is the
Peak
Power
.
16. Calculate the
Noise Measurement BW
and the
Noise Center Frequency (CF)
using the
following equations:
17. Calculate the
Power in Band
for the spectrum from step 13 using the
Noise Measurement
BW
and
Noise CF
values from step 16.
Note
Power in Band
is a built-in function in the NI Spectral Measurements Toolkit.
18. Calculate the
Average Noise Power
using the following equation:
19. Record either
Peak Power
(from step 14) or
Average Noise Power
(from step 17).
According to the frequency tuned to with the PXIe-5665, record whichever value is greater
as the
Fundamental Power
or the
Harmonic Power
.
20. Repeat steps 7 to 19 for the second harmonic, which is twice the test frequency.
21. Calculate the SHI using the following equation:
SHI = 2
(
Fundamental Power
) -
Harmonic Power
-
RF Attenuation
22. Repeat steps 7 to 20 for all test frequencies listed in Table 36.
Noise Measurement BW
Span
2
------------
10
kHz
2
------------------
–
=
Noise CF
Center Frequency
Span
4
------------
10
kHz
4
------------------
+
+
=
Average Noise Power
Power in Band
10
Noise Measurement BW
Resolution Bandwidth
----------------------------------------------------------
10
log
–
=