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NI PXIe-5601 Calibration Procedure
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© National Instruments
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14. Adjust the RF source power, in dBm, so that the channel A power reads 20 dB below the
1 dB compression point listed in Table 19. You do not need to correct the channel A power
for the RF frequency.
15. Record the
Spectrum Analyzer Power
. You do not need to correct the spectrum analyzer
power with the
IF Correction Factor
.
16. Calculate the NI 5601 measured gain using the following formula:
Measured Gain
=
Spectrum Analyzer Power
-
Channel A Power
17. Repeat steps 14 to 16 with 1 dB higher RF source power. The gain calculated in step 16
becomes the
Current Measured Gain
. The gain calculated in the previous iteration becomes
the
Previous Measured Gain
.
18. Calculate the
Gain Change
using the following formula:
Gain Change
=
Current Measured Gain
-
Previous Measured Gain
19. Repeat steps 14 to 18 until the
Gain Change
equals -1 dB or less (more negative). You can
repeat Steps 14 to 18 with a finer power increment in step 17 to obtain more accurate
results.
20. Correct the last channel A power measured in step 14 using the following formula:
Input Compression Point = Channel A Power + RF Input Calibration Factor
Use the appropriate RF frequency for the channel A sensor. Calculation of the
RF Input
Calibration Factor
may require linear interpolation.
21. Compare the
Input Compression Point
to the verification test limits in Table 19.
22. Repeat steps 1 to 21 for all the frequencies in Table 17.
Note
NI recommends keeping your RF signal generator enabled when repeating
steps unless making a connection change. Keeping the signal generator enabled
reduces the wear on the RF signal generator relays. After making a connection
change and enabling your generator, wait 5 seconds for the system to settle.
23. Close the NI 5601 session using the niRFSA Close VI or the
niRFSA_close
function.
Table 19.
Gain Compression Verification Test Limits
Frequency
1 dB Compression Fine
10 MHz to <120 MHz
>-2 dBm
120 MHz to <330 MHz
>2 dBm
330 MHz to 6.6 GHz
>6 dBm
Note
: At RF input, -10 dBm reference level.