© National Instruments Corporation 11 NI PXI-5600 Calibration Procedure
Verifying Internal Reference Frequency Accuracy
Caution You must allow a warm-up time of at least 20 minutes before you begin the
remaining verification procedures.
Note The NI PXI-5600 internal reference frequency is accurate to within 0.5 Hz of
10 MHz (50 ppb initial accuracy).
To verify the internal reference frequency accuracy, write a program that
includes the following steps:
1. Call
niTuner_init to open the session.
2. Call niTuner_setAttenuation and set the NI PXI-5600 with the
following parameters:
• refLevel =
0
• mixLevel =
–30
3. Lock the spectrum analyzer to the 10 MHz OUT square wave output
of the rubidium source.
4. Set the following parameters on the spectrum analyzer:
• center frequency =
110 MHz (examine the 11
th
harmonic of
10 MHz)
• span =
600 Hz
Table 2. Temperature Correction Coefficient Specifications
Verification Results What to Do
TempCo
new
< –0.12
OR
TempCo
new
> –0.03
Return the NI PXI-5600 to NI for repair.
–0.12 ≤ TempCo
new
≤ –0.03
AND
{TempCo
old
– 0.02 > TempCo
new
OR
TempCo
old
+ 0.02 < TempCo
new
}
Adjust the temperature correction
coefficient (refer to the Adjusting the
Temperature Correction Coefficient
section for detailed instructions).
–0.12 ≤ TempCo
new
≤ –0.03
AND
TempCo
old
– 0.02 ≤ TempCo
new
≤ TempCo
old
+ 0.02
There is no need to adjust the
temperature correction coefficient or
to repair the NI PXI-5600.
