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Principles of Operation
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Sync Signals
This section describes the following aspects of the sync signals:
• Sync signal selection, and
• Sync signal insertion (Sync Sentinel).
Sync Signal Selection
To digitize the incoming video signal, the DT3155 frame grabber
requires both horizontal and vertical sync signals. The DT3155 board
determines this sync information from the current input channel or
from one of the unused composite video input signals on the board.
You select the sync source in software.
The sync signal is fed directly into the sync circuitry. The voltage level
of the analog sync signal is compared with the sync threshold to
determine when the sync is asserted. The sync period is defined as
the portion of the sync signal that falls below the sync threshold. The
sync is then used to generate the horizontal and vertical timing for
the input section of the DT3155 board.
On the DT3155, you can program the sync threshold. Possible
threshold limits are 50 mV, 75 mV, 100 mV, and 125 mV (nominal is
125 mV).
Содержание DT3155
Страница 1: ...DT3155 UM 13856 K User s Manual ...
Страница 4: ......
Страница 8: ...Contents viii ...
Страница 16: ...About this Manual xvi ...
Страница 17: ...1 1 Overview Features 2 Supported Software 3 Accessories 4 ...
Страница 41: ...25 3 Supported Device Driver Capabilities DT3155 Device Driver Capabilities 26 Initialized Control Values 44 ...
Страница 62: ...Chapter 3 46 ...
Страница 86: ...Chapter 4 70 ...
Страница 87: ...71 5 Troubleshooting General Checklist 72 Service and Support 76 If Your Board Needs Factory Service 80 ...
Страница 97: ...81 A Specifications ...
Страница 100: ...Appendix A 84 ...
Страница 101: ...85 B Connector Pin Assignments Video Input Connector J1 86 Video Coaxial Connector J2 88 ...
Страница 122: ...Appendix C 106 ...
Страница 132: ...Index 116 ...
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