Transmission Characteristics
Typically frequency modulated TV is used on frequencies above 1240 MHz (1.24 GHz), where there is enough bandwidth for such wideband transmissions. This is often used as a repeater's input frequency, with output being standard VSB on the four channels listed above.
In a nutshell
- below 1.24 GHz: Vestigial Sideband
- above 1.24 GHz: FM, PSK etc...
The quality of transmission is expressed as a "p-level"; "p" standing for "picture". P-levels range from zero to five, increasing as the picture becomes more viewable. P-0 signifies a state in which sync bars are visible, but the picture is too snowy to be seen; this occurs at a minimum signal strength of 3db. Each level represents an increase of 6db over the previous; P-5 is 30db above P-0 and represents a perfectly clear picture.
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