[opendtv] Re: VHF vs UHF coverage
- From: Albert Manfredi <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 23 May 2009 18:01:11 -0400
Richard Hollandsworth wrote:
> NTSC power has always been measured and specified
> as PEAK power, whereas DTV power is always
> measured and specified as AVERAGE power. Peak
> power for DTV is about 7 dB higher than average
> power.
I think you mean NTSC peak is 7 dB higher than NTSC average, yes? With
scrambling, DTV average and peak power should be virtually identical, I think.
> DTV also has a performance advantage of about 5
> dB for a total of 12 dB.
I guess some people are skeptical about this extra 5 dB. Also, because analog
viewers can put up with a lot of visual "abuse," where digital viewers have to
contend with a cliff, I would err on the side of being more forgiving with DTV
signal margin.
I do totally agree with your point about UHF receive antenna gain vs VHF
antenna gain, however. It's just that propagation models do show a lot more UHF
falloff at the fringes, with low altitude receive antennas, etc.
Just 3 weeks and we'll know just how accurate those FCC predictions were for
VHF. My fingers are crossed.
Bert
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