Interesting. From today's "Broadcast Engineering RF Update" email I received.

http://broadcastengineering.com/RF/expected-dtv-coverage-market-0101/

Edit add: I didn't realize that CH-22 and CH-32 out of Salem were moving their transmitters to Portland.

Here's the link directly to the Portland maps; http://www.fcc.gov/dtv/markets/maps_report1/Portland_OR.pdf

Wow, look how the high band V's who will run their DTV on their VHF channel after the analog shutoff drop power (and their electric bill) while gaining coverage. The low band V's who run their DTV on UHF increase their power by a factor of 10 while losing coverage.

And obviously the map contours don't take terrain in to account.

I know the RF isn't going to get into the valleys in the foothills!

Yeah, anybody on the lower 6 isn't going to realize the bennies of DTV as well as the higher ones do.

Having watched off and on for a while now, CH 2 & 6 are marginal at best, reception wise. A nice antenna does the job, but the rabbit ear deals are spotty for them.

I would move off quick, and get a new higher channel. Those decisions are already made though, so we just get to see who does well and who doesn't.

It almost seems too good to be true that some of these very spectacular coverage areas could be obtained at relatively low power levels. After checking a few markets' reports, I noted that the majority of stations are trying to duplicate the coverage area of the analog signal. However, if you go to the Montgomery, AL market and look up WSFA, you will be in for something wacky! WSFA is planning to stay on VHF Channel 12, but they intend to reduce power to 1.16 kW! They will lose coverage as a result, and some of the areas lost are not served by other NBC affiliates.

There are a handful of stations that will be operating DTV on the VHF-Low channels, such as WPVI, Philadelphia (a complete list was previously posted on this forum). If the VHF-Low holdouts experience reasonably reliable reception, could the FCC be persuaded to license more DTV stations on the VHF-low channels?

It would have been nice if the FCC would have used Longley-Rice coverage maps (which do a better job of accounting for terrain) for this study. The maps that they presented are fairly poor indicators of coverage in hilly areas.

At any given frequency it takes less power to get the same coverage with digital. It's not the field intensity, mind you, it's the ability to achieve the desired S/N at the front end of the receiver (full quieting). The analog curve is gradual as the S/N slowly falls. In digital, you reach a steeper knee and it's gone.

Also, again I must point out the FCC has every intention of examining coverage after the cessation of all the full power analog signals to see how the predicted digital coverage is performing. There aren't going to be any sudden changes in allocations after the analog shut down.

The FCC predicted coverage does take terrain into account, just not as accurately as Longley/Rice. The FCC method misses terrain peaks more because of the data set and not the algorithm. The kind of mapping we have today just wasn't around back when Ug and Og derived the FCC methods of coverage prediction. Also, Longley/Rice can be overly generous. The real coverage usually falls between the two methods.

Remember, coverage is not supposed to be the variable. Class determines range and height determines power.

"Longley/Rice can be overly generous"

Interesting! what sort of conditions should one watch out for, when studying L/R plots?

Look at the FCC contour, then the L/R, then examine the terrain in between the two, then make your best guess.

Just on a lark, I bought one of the RCA converter boxes last summer. Since I live behind two ranges of hills 60 miles SW of Portland, I was expecting nothing in the area of DTV, except what I could get from OPB in Corvallis.

Just for the heck of it, I pointed my medium sized outdoor antenna to Portland just to see if I could lock onto any kind of signal whatsoever...and lo and behold....all of the digitals from Sylvan came up! 2, 6, 24 and 32 all at varying strengths.(32 is the worst due to the strong signal strength of analog 32 which is right next to the digital allocation for them) 2 and 6 are absolutely solid in all conditions...even when there was 6" of snow piled up on the antenna. I haven't seen a plot of the contour of any of these stations but past experience suggested to me that UHF signals from Portland were going to be a pipe dream...but you never know until you try!

(Of course, when I move into my new place down the road a mile next month, I will probably get ZERO signals from Portland...multipath hell down there)

Still can't get 49 on my DTV (no signal) but strong enough RF to get it on my converter box...what gives? On same antenna via splitter!

How about antenna no splitter direct to DTV. Does it work then?

A few possibilities:

1. TV is less sensitive than converter box.
2. Much longer wire from splitter to TV than to to converter box, therefore more loss of signal.
3. Wire from splitter to TV is bad (open-shorted-?), but ok to the converter.
4. One splitter port is bad.

Suggestion: try the converter box into the DTV ... see if you get 49.

My DTV coax is 4ft off splitter, converter box to bedroom is around 35ft. My only assessment is that my DTV has less sensitivity than the box.
All other channels are recieved on DTV are fine including the new chan 22 site which had breakups before. Where talkin reception in NE Salem near I-5...but wait...there's more...just did a rescan of my converter box...no longer see's 49 or Digital 30...gets analog 49...what gives?

I don't know about 30 (digital physical channel for 12) signal strength here in Hillsboro is the same as it usually is (high 90s out of 100), but digital 48 (49) is running only in the 60's tonight,and has been as low as the 50's a few days ago... (mid 80's to mid 90's are the norm here for it).

48's been in the mid-30s here for about a week now! I can't even watch South Park or Frasier without ha ing t br k p on me ev y oth r sec d ... . .... .. ;o)