OTA DTV Stations using RF channels 2 thru 6---do they like or dislike it?

[Watt Hairston]

Isn't it ironic that what was once prime and no-mans-land (respectively) real estate TV RF spectrum have now swapped positions! VHF presents a multitude of issues; noise, phase cancellation, wrong receive antennas and high percentage of bandwidth as compared to UHF. If a TV operator is saying they are pleased with low-band and perhaps high-band performance, they're smoking something and we ain't talking the transmission line!

Best regards,

w/

[DeadElvis]

I've heard thsat WMC in Memphis has a filed a request to move from 5, but I don't know all the details.

WMC has filed for a replacement channel on 17.  That would displace an LD that is Spanish, with some local programming.

I get a reliable signal from WMC, for the most part.  Unlike most viewers, I know enough to build a lo-band loop for 5; it works pretty well.  But it does have issues with electrical interference.

What's unfortunate is that WMC could have gotten another channel.  "The suits," I'm told, were afraid to give up that heritage channel.

DE

[w9wi]

The other thing is that analog and digital power comparisons are apples & oranges. 

TV stations (both analog & digital) are amplitude-modulated, which means the power is always changing.

- Analog power is measured at peaks, when the station is using the most power it will ever use.  (the times of these peaks are predictable)
- Digital power is measured as an average over time.

VERY roughly, digital average power is about 1/2 peak. 

To put it differently...

WWNY's 25kw average digital is 50kw measured the way they measured it in analog.

WWNY's 300kw peak digital is 150kw measured the way we measure it in digital.

50kw peak digital vs. 300kw peak analog is still too much of a difference, but it's a lot closer than 25kw vs. 300.

[BobOnTheJob]

To answer the question of why everyone's power is lower, the fact that they are now shoe-horning the same number of signals into fewer channels is a factor as well. On paper, they'll interfere with each other at previous power levels. In reality, they are interfering with each other at the new power levels. Great example...in Charleston,IL you can watch WILL DT 9 (42 miles) on rabbit ears in the afternoon when the band is 'normal'. In the morning, the most directional yagi won't receive WILL because WISH DT 9 in Indianapolis at 107 miles causes just enough interference that WILL won't lock. HDTV needs MORE protection to be reliable, but the FCC gave equal or less on paper--and a lot less in reality. That said, I've had a great experience with HD reception (realizing I'm in the minority). At 70 air miles, all of the Louisvville,KY stations are there 24/7 (including WHAS DT 11) and WKRC DT 12 Cincinnati is about 90% reliable at 80 air miles. It took a spectrum analyzer on my TV coax to see some FM overload which I notched out. That step alone made a large difference, but the average viewer doesn't have access to such equipment so they walk away with a very low opinion of OTA HDTV.   

[frankberry]

Digital power is measured across the entire 6MHz channel since there is essentially no carrier.
In our case, it takes a transmitter rated at 60 kilowatts for NTSC to produce about 20 kilowatts of digital.

[spunker88]

Up until last year we had CIII-6 in Ottawa, ON with 50kw ERP and CJOH-6 in Deseronto, ON (west of Kingston, ON) with 100kw. During tropo it was possible to pull in both just by moving the antenna.

Now CJOH-6 is still around in analog at 100kw, but CIII-6 went digital on channel 6 with 3.3kw digital ERP. I wonder if the interference from CJOH-6 via tropo is enough to affect reception of CIII-6 southwest of Ottawa going towards Perth/Smiths Falls. This area is also served by the big CIII-2 Bancroft so at least they have another Global signal to view if they can't get Ottawa at least until they shut off analog in Bancroft.