CompuServe Messages

I have noticed many people asking the question "What is Broadcast Quality? Maybe I can shead some light on this. The FCC has set a standard for the quality of a video signal to be broadcast, be it sent by whatever method, ie, air, satelite, fiber-optic, or cable. That basic standard is known as RS 170A. You would need a waveform monitor and a vectorscope to actually see or measure the signal to insure that it complies. There are boards available for the computer that will turn your wideo monitor into a waveform monitor and vectorscope. These are the main specifications: Vertical Blanking 21 lines Horizontal Blanking 10.49-11.44 micro seconds Sync Level 40 IRE units Burst Level 40 IRE units Black or Pedestal 7.5 – 10 IRE units Peak Video Level 100 IRE units Chroma Level 120 IRE units There are many more measurments, such as subcarrier/Horiziontal Phasing, the front porch, back porch, breezeway ( I don't know where they got these names ! ), pre & post equalizing pulses, etc., but these are the main ones, and when these are correct, the others generally fall in. In a television facity, great care is (should, anyway) taken anytime a dub is made, or editing of material, to ensure the quality of the signal. In fact, the signal itself is quite unstable, and degenerates rapidly with dubbing and editing, due mostly to the mechanical nature of the wideo tape itself. It actually stretches and relaxes, and while this is almost immeasurable, it creates timing problems in the signal. The television facility uses Processing & Distribution Amplifiers and Time Base Correctors to maintain this critical timing of the signal. Before any program is "aired", a Technical Evaluation is performed on the program, which is viewed, full-length, and the specifications listed above are measured and documented, along with audio information, captioning, format, amol encoding information, etc. Anyway, this is a most basic of 'primer's', but it gives an overview of what is meant by 'Broadcast Quality'.