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Appendix G: Calibration
G–18
VX4101A MultiPaq Instrument User Manual
The following additional steps are performed during initial factory calibration,
when the channel 3 option is available. This step is not part of the normal
calibration sequence, and is included here for completeness only.
Channel 3 Pre-Scaler BIAS Adjustment.
1. Set up the high frequency source for a sine wave at 1000 MHz ±100 kHz at
–21 dBm, and connect it to the prescaler (channel 3) input.
2. Send the command
CALibrate3:BIAS
This command takes approximately 2 seconds to execute.
There are two clock sources available which the Counter can use as its reference
oscillator. These are the internal 10 MHz clock located on the VX4101A CPU
card, and the VXI backplane 10 MHz clock.
Either or both of these sources could be used in the actual operation of the card.
It is recommended that both sources be calibrated.
Selecting a noncalibrated source during operation will generate an error. For best
results, the VXI clock should be calibrated in the actual system in which it is
used.
Calibrate the clock sources as follows:
1. Connect the High Accuracy Clock Standard into the Channel 1 input, and set
it to 10 MHz @ 0 dBm. To do this, send the following command:
INP1:IMP50
2. Select the source of the clock to be calibrated, as follows:
SOURce:COSCillator ROSC
3. Calibrate the internal clock with the following command:
SOURce:ROSCillator INTernal
4. Calibrate the VXI backplane clock with the following command:
SOURce:ROSCillator CLOCk10
5. Calibrate the Option 1T, TXC01 with the following command:
SOURce:COSCillator TXCO1
Factory Calibration
System Clock Calibration