PXIe-5185/5186 Calibration Procedure
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© National Instruments
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23
Verifying Timebase Accuracy
To verify the timebase accuracy of the PXIe-5185/5186 compare the peak frequency of a leveled
sine wave measured by the PXIe-5185/5186 and the value sourced by the calibrator. Table 8 lists
the settings.
1.
Configure the PXIe-5185/5186 with the following settings:
•
Vertical coupling:
DC
•
Input impedance
: 50
Ω
•
Max input frequency
:
(PXIe-5185)
3 GHz,
(PXIe-5186)
5 GHz
•
Range
: 1 V
pk-pk
•
Sample rate
: 12.5 GS/s
•
Minimum number of samples
: 1,048,567
2.
Connect the calibrator test head directly to the channel 0, 50
Ω
input of the digitizer.
3.
Configure the calibrator output impedance to 50
Ω
.
4.
Configure the calibrator to output a 1.0 GHz leveled sine wave with peak-to-peak voltage
amplitude of 0.90 V.
5.
Enable the calibrator output.
6.
Wait 2.5 s for settling, then record the measured peak frequency.
7.
Use the following formula to calculate the frequency difference:
TBerror
= (
f
- 1.0E+9)/1.0E+3
where
f
= measured frequency
8.
Compare the error to the
Test Limit
shown in Table 8.
Note
Timebase verification is only required on one channel.
Adjustment
If the PXIe-5185/5186 successfully passed each of the verification procedures within the test
limits, then an adjustment is recommended but not required to warrant the published
specifications for the next year. If the digitizer was not within the test limits for each of the
verification procedures, you can perform the adjustment procedure to improve the accuracy of
the digitizer.
An adjustment is required once a year. Following the adjustment procedure automatically
updates the calibration date and temperature in the EEPROM of the digitizer.
Table 8.
PXIe-5185/5186 Timebase Accuracy Limits
Channel
Function
Input
Impedance
Range
(V
pk-pk
)
Test Point
(V
pk-pk
)
Test Limit
0
Timebase
50
Ω
1.0
0.9 at 1 GHz
±25 ppm
(25.0 kHz)
