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802R-PCI Video Test Generator User Guide (Rev A) 13
Calibrating frequency
All frequencies associated with the generator are derived from a common frequency
reference, which can be calibrated using the rate calibration command RATC.
To reduce all frequency errors to zero:
1. Measure any convenient frequency from the generator using a very accurate frequency
counter.
For example, measure the horizontal TTL separate sync frequency with the DMT0660
format loaded and the horizontal rate temporarily set to 100KHz. Do this by typing
FMTL DMT0660;HRAT 100E3;ALLU
on the command line and measuring the TTL horizontal sync frequency.
2. Divide the frequency that you expect by the frequency that you measure and enter that
ratio using the RATC command.
For example, if you measure 99.9955782499875 kHz, when you expect
100.000000000KHz, then divide 100.000000000KHz by 99.9950002499875kHz and
type
RATC 1.0000442194553987
This will raise all rates output by the generator and make them exact.