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PXIe-5665 Calibration Procedure
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© National Instruments
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47
18. Measure the spectrum on the PXIe-5665.
a.
Find the peak value of the spectrum.
b.
Confirm that the peak value is between -16 dBm and -4 dBm. The peak value is the
PXIe-5665 Tone Power
. This value is used in step 18(d).
c.
Notch filter the spectrum by replacing the appropriate number of bins from the center
of the spectrum according to Table 24 with bins of -130 dB in value. The resulting
spectrum is the
Notched Spectrum
.
d.
Calculate the
Notched Spectrum
Response
using the following equation:
Notched Spectrum Response
(dB) =
Notched Spectrum
(dBm) -
PXIe-5665 Tone Power
(dBm)
e.
Create a list of target spurs from the
Notched Spectrum Response
(dB)
that have a
level greater than -90 dB.
f.
If any two spurs are within ±500 Hz of each other, retain only the spur with the greater
power magnitude. This reduced list is used in step 19(a).
Note
The RF source 2 indicated for use in this procedure exhibits spurious
responses that have a frequency spread of 500 Hz. Any target spur found within
±500 Hz of an RF source 2 spurious response is considered to be from the
RF source 2 because of this frequency spread.
19. Eliminate any RF source 2 spurious responses from the list of target spurs.
a.
Tune the spectrum analyzer to the frequency of each target spur in the reduced list
from step 18(f).
b.
Measure the spectrum and perform a peak search on the measured spectrum. This
value is the
Spectrum Analyzer Peak Value
.
c.
Convert the
Spectrum Analyzer Peak Value
units to dB using the following equation:
Spectrum Analyzer Peak
(dB) =
Spectrum Analyzer Peak Value
(dBm) -
Spectrum Analyzer Tone Power
d.
If the value of the
Spectrum Analyzer Peak (dB)
is 5 dB or more below the spur level
in the reduced list from step 18(f), retain the spur level, otherwise discard the value.
20. Compare the spur values from the sorted list in step 19(d) to the verification test limits in
Table 25.
Table 25.
LO-Related Spurious Responses (Sideband Spurs)
Verification Test Limits
Center Frequency
As-Found Limit (dBc)
As-Left Limit (dBc)
*
100 MHz to 3.6 GHz
-73
-75
3.6 GHz to 14 GHz
†
-73
-75
*
Refer to the
section of this document for more information
about as-left limits.
†
Center frequencies >3.6 GHz apply only to the PXIe-5665 14 GHz VSA.