Quantum-data 881 Manual do Utilizador descarregar pdf (Página 105)

881/882 Video Test Generator User Guide (Rev A.22) 87

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

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Quantum-data 881 Manual do Utilizador Página 105