Quantum Data 881, User Manual

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882 Video Test Instrument User Guide (Rev A.35) 75
Calibrating the generator
The 882 generator can calibrate itself. Once calibrated, the generator does not require
periodic calibration. There are no physical controls to adjust. All calibration is electronic.
Calibration factors are saved in non-volatile memory.
Calibrating signal level
The calibration accuracy of the generator for analog video voltage swing is specified to be
±14 mV (or ±2% for a nominal 700 mV signal). Using a typical oscilloscope such as a
Tektronix VM700T, which might have a swing measurement accuracy of ±14 mV, readings
should be between 674 mV to 726 mV.
You can set the analog output calibration factors to values other than those set by the
generator's own self-calibration function. Each channel is calibrated using two
independent, zero calibration points, and two independent, slope calibration points.
Interpolation equations for the different video types are used to set the caldac values that
control the output sync and voltage levels to the correct values.
You can calibrate the generator using the front panel keys or the command line interface.
Follow the procedures below to calibrate the generator.
To self-calibrate the generator using the front panel:
1. (Optional) Load the outputs of the generator. Although it is not necessary to load the
outputs during self-calibration, attaching a nominal load may yield a slight increase in
accuracy.
2. Press the Tools key. The Tools menu appears on the generator’s display as shown
below.
3. Choose the System item by pressing the adjacent soft key. The System menu appears.
Press the - key to scroll down until the CalFactor item appears.
System
Sequence
Probe
AFC
Analyzer
Reports
ImgShift
CEC
CalFactor Host
Network About
Serial Gpib
BootFrom Init