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NI PXI-5404 Calibration Procedure
The following procedure determines the characteristics of the SYNC DAC. The SYNC DAC
determines the duty cycle of the CLOCK out. The program writes several values to the SYNC
DAC and measures the duty cycle of the CLOCK out for each of these values.
The program then passes the SYNC DAC values and measurements of the resulting duty cycles
to
niHSSources_CalAdjust
(niHSSources Cal CalAdjust VI).
The duty cycle of an uncalibrated module depends on the frequency of the CLOCK out. The
calibration procedure determines SYNC DAC values that compensate for the frequency
dependency of the duty cycle.
For each frequency, initiate a generation at that frequency. Pass the zero-based index to the
niHSSources_InitializeDutyCycleCalibration
function (niHSSources Cal
InitializeDutyCycleCalibration VI).
To calibrate and adjust the duty cycle of the CLOCK out, complete the following steps:
1.
Call
niHSSources_ApplySessionConstants
(niHSSources Cal
ApplySessionConstants VI) to instruct the driver to use data from previous calibration steps
of the session. This function ensures that the driver uses the values calculated during the
VCXO and SINE out amplitude calibrations. Set the following parameter:
•
sessionHandle
—The handle of the calibration session for the module
2.
Connect the CLOCK out to an oscilloscope.
3.
Set the termination of the oscilloscope listed in Table 1 to 50
Ω
.
4.
Repeat the following steps for each frequency index listed in Table 6:
a.
Call
niHSSources_GenerateWaveform
(niHSSources Cal GenerateWaveform
VI) to generate a sine wave at a frequency listed in Table 6. Set the following
parameters:
•
sessionHandle
—The handle of the calibration session for the module
•
waveformType
—
niHSSources_SINE
Table 6.
SYNC DAC Frequencies
Index
Frequency
SYNC DAC Values
Number of
Measurements
0
50 kHz
48, 60, 70, 80, 115, 150, 172, 182, 192, 200
10
1
15 MHz
48, 60, 70, 80, 115, 150, 172, 182, 192, 200
10
2
30 MHz
45, 57, 67, 77, 87, 130, 165, 175, 184, 196
10
3
45 MHz
38, 50, 60, 70, 85, 120, 155, 165, 175, 192
10
4
60 MHz
38, 50, 60, 80, 105, 125, 145, 155, 165, 177
10
5
75 MHz
75, 81, 87, 93, 99, 105, 111, 117, 123, 129
10
6
90 MHz
80, 84, 88, 92, 96, 100, 104, 108, 112, 116
10
7
105 MHz
70, 73, 76, 79, 82, 85, 88, 91, 94, 97
10