Videotek VTM-2000 Specifications download pdf (Page 36)

Operation

VTM-200 Installation and Operation Handbook 3-20

Calibration Pulse

Checking on the accuracy of the waveform graticule and the vertical gain of the

VTM-200 circuits that process composite waveforms, a calibration pulse is selected for

display in lieu of the normal composite waveform. The SETUP menu item CAL has as

the values ON and OFF. If CAL pulse is selected, a squarewave several cycles in

duration will be displayed. The squarewave amplitude corresponds to 140 IRE in

NTSC and 143 UNITS in PAL and is processed by the same circuits that normally

process the composite waveform. By adjusting the squarewave position vertically with

the front panel WAVEFORM POSITION-V knob, it should be possible to place the

top and bottom of the squarewave directly on the -40 and +100 lines in NTSC and -43,

+100 lines in PAL of the unzoomed waveform graticule, in order to verify calibration.

Calibration Interval

Calibration is recommended under any of the following conditions:

• Every 12 months

• When critical components are replaced

• After exposure to temperatures outside of the specified operating or storage

temperatures

NOTE: If calibration is needed, refer to Appendix B for service and support.

STATUS, ERROR, and SC/H Indicators

Between the waveform and vector displays, and on full screen waveform and vector

displays, the VTM-200 shows STATUS information, and for serial digital inputs only,

ERRORS information. The background color that surrounds the indicating text

provides the user with useful information, summarized in the tables that follow.

Definitions of the listed errors:

• GAMUT ERROR - When the transcoded RGB representation of a digital input

extends above 0.7V or below 0V during the active picture portion of the video.

• DATA ERROR - When the presence of a signal is detected on a digital input but

TRS (Timing Reference Sequence) cannot be detected.

• EDH ERROR - When the presence of the EDH header is detected and either the

active picture or full field CRCs (Cyclic Redundancy Checks) calculated by the

VTM-200 do not match the CRC values embedded in the selected digital video

signal.

• EDH PRESENT - When there is no EDH ERROR and the VTM-200 has detected

the presence of the EDH header on the selected digital video input.

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Videotek VTM-2000 Specifications Page 36