The VM771 VIDEO MASTER is a baseband video processor that stabilizes video levels, clamps out low frequency interference, and automatically corrects Luminance-to-Chrominance Inequality. The VM771 input level operating range is 0.5 to 2.0 Volts peak- to-peak. Within this input range the VM771 will control the following parameters at the output:
1. Sync level is automatically gain-regulated to 40 IRE Units.
2. White level is automatically gain-regulated so as not to exceed 100 IRE Units (but still permits a fade to Black). White level is not clipped, but retains a linear gray scale.
3. Output video level is regulated to 1 volt peak-to-peak (at 100% White level).
4. Luminance-to-Chrominance ratio is automatically corrected, thus compensating for cable slope loss or other sources of high frequency attenuation.
5. Back Porch Clamping eliminates all incoming low frequency interference such as 60 cycle ground loops, even when the video signal is removed!
Since VM771 processes sync and picture peak voltages through a time-gated Automatic Level Control System, the time relationships within a video signal remain unaffected. Therefore horizontal Sync, Color Burst Timing, and Chrominance Phase retain their original relationship. This feature distinguishes the VM771 from Proc Amps that strip and re-insert new sync signals.
The VM771 insures constant standard video signals even though video from a multitude of variable level sources are used. This helps to insure correct CATV Scrambler operation and video recording levels. Each VM771 is a Stand-alone device, requiring no front panel rack space, "Mainframe", or other common equipment.
The Processor can be mounted on the side rail on the back of a rack directly behind the TV Modulator Switcher or other video equipment. The Processor is in a fully RF shielded metal enclosure, allowing operation in the vicinity of potential sources of RF interference. No adjustments of any kind are required at any time so the Processor can be mounted out of the way. A "Video Presence" indicator shows that a video signal is present at the output to identify signal continuity.