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DTV Power vs Analog Power

radioguybroadcasting said:
Yes, 7.56KW Digital compared to 74.1KW Analog.
Click to expand...

This is nuts! :mad:
Their new coverage map no longer includes Dover, DE. :'(

Are they doing this to yield Dover's ABC choice to WMAR who will relocate to UHF 38 (now used by WJZ) using 1 Megawatt? ???

I can get 38-DT using a simple bow-tie aerial on the first floor 24/7, it's the most consistent signal I receive as I'm never dissapointed. :)

This being the case, from Andy in Dover, bye bye PVI. Call me when you get a new logo. :D
 
Did you mean it presently has 74.1 KW analog or 7.41 KW? That's a 10 dB difference.
Hopefully this means WNYZ will be clearer in central NJ
 
Nick said:
Did you mean it presently has 74.1 KW analog or 7.41 KW? That's a 10 dB difference.
Hopefully this means WNYZ will be clearer in central NJ
Click to expand...

74.1.

Do be aware that comparing analog and digital power is like comparing apples & oranges.

The power of a TV station (analog or digital) is constantly changing. At any given instant, WPVI's analog power is probably *not* 74.1kw. At any given instant, their digital power will probably *not* be 7.56kw.

An analog station has power peaks at regular and predictable intervals. Every 1/15750 second, a "synchronizing pulse" is sent. Since the picture will break up if these pulses are lost, they are transmitted at the highest possible power. So we *know* there will be a pulse of maximum possible power at 0 seconds, 1/15750 second, 2/15750 second, 3/15750 second, etc..... The power of an analog TV station is measured at the times when the maximum possible power is being transmitted -- 74.1kw is the highest power WPVI analog ever transmits.

A digital station also has power peaks -- but they *don't* happen at regular and predictable intervals. We don't know when WPVI digital will transmit maximum power. So instead, digital power is *averaged* over a period of time - a second or so. WPVI-DT's power may average 7.56kw over a period of time, but on occasion it's considerably higher. Papers suggest it could be on the order of 4 times the average power.

So if you measure their digital power the same way analog power is measured, the figure is a lot closer to 30kw. That's still lower than their 74kw analog power, but it's a whole lot better than 1/10! (and since these things are logarthmic, the difference between 30 and 74 is a lot smaller than it looks)

(since *someone* is going to nitpick, yes, the 15750 figure above is only for black and white, when color TV came along it was changed to 15734.234... 15750 is a lot neater and it makes the point...)
 
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