reprinted from Television Technology

by Jim Alfonse


Tri-Sys Designs

Tewksbury, MA



My job for the last 20 years has involved evaluating and designing various systems for broadcasters, manufacturers and end users around the world. Last year, I finished a long‑term contract with Avid Technology in which I tested and evaluated all its products for video quality and standards compliance.

All these customers want a proper video signal, but unless all applicable standards are met, a video program can be rejected by a network or fail to appear on your television screen.

When dealing with large or small systems, video alignment between input sources is crucial. With high definition coming of age, I need a reliable and friendly method of monitoring both HD and SD, and the Leader LV7500A SD/HD provides monitoring capabilities for both standards.


The LV5700A works particularly well for me in mixed analog and digital environments, where analog video is digitized and processed alongside other digital signals. A standard‑definition SMPTE 259M digital data stream is divided into 1,716 samples (words) per line of video, and synchronization is accomplished by allocating certain word groups for this purpose. These groups are known as the End of Active Video (EAV) and the Start of Active Video (SAV), and both occur on every line of video.

In analog video, the horizontal reference point is represented by word 1473 in the digital stream. This provides for H‑sync continuity during analog/digital and digital/analog transitions, using the EAV and SAV as timing reference signals.

The EAV and SAV are displayed as a large pulse on the LV5700A. These pulses can be used to align two digital video streams even if they are of different resolutions, permitting seamless switching and transitions. The LV5700A's menu allows for quick and easy alignment of these pulses.
The LV5700A also has a useful screen capture feature if there is a question Involving a signal, a still can be captured and exported for evaluation‑after all, a picture is worth a thousand words.
The LV5700A SD/HD has an easy‑tolerant menu‑driven interface. In addition to signal alignment, it is a must‑have for video monitoring to ensure standards compliance.
I've recommended the LV5700 system for clients since its introduction. Even inexperienced users have had no problem performing critical measurements in both SD and HD video.

Jim Alfonse is owner of Tri‑Sys Designs, a company specializing in systems design, integration and video analysis. He can be reached at jim@tri‑sysdesigns.com.
For more information, contact Leader Instruments at 714-527-9300 or visit www.leaderusa.com.


Jim Alfonse, owner of Tri-Sys Designs, is a Systems Integrator with twenty-five years experience in the Broadcast Industry. He's designed, built and commissioned installations from Satellite News Vehicles to Production Suites to OB vans. Jim has been involved with several equipment manufacturers performing video standards compliance and signal integrity testing.
For more articles on various subjects visit www.tri-sysdesigns.com