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FCC DTV Reception Maps Website

post #1 of 20
Thread Starter 
The FCC website has a new DTV reception calculator/prediction page at http://www.fcc.gov/mb/engineering/maps/. Enter your adders or location and get a list of DTV stations in four categories: strong, moderate, weak, no signal. After the calculations, click on the stations shown on the left to get physical RF channel, receive power in dBM, direction, pre-transition RF channel and a link to the FCC gain/loss map. The results are based on the post-transition allotments. Which now won't take effect for four more months for many stations.

Interacts with google map. You can drag & drop the location marker and get a re-calculation. But I don't see any digital low power stations showing up on the list. So this may be of little use for those dependent on LPs and TXs.

For my location, the prediction for reception is pretty close to what I expect, but I get some of the "weak" stations which are already on their post-transition allotment just fine. So their model may shade on the conservative side. Still, a useful site to compare to antennaweb.org or tvfool.com to see what each of them say for a location.
post #2 of 20
As with most government things... it's not worth much. According to the results for my location, KMOS comes up as "No signal". Funny it should say that, as that station comes in 24/7 with no dropouts, and at 90 percent signal strength... the strongest channel I have!
post #3 of 20
Clicking the station letters give you estimated power received which is lower than what TVfool predicts.

For my location it is slightly conservative, but a better predictor than antennaweb.

Dragging and dropping the marker is a lot easier than entering your information again and again. I think it is a nice tool.
post #4 of 20
I punched in my address to the site. One of the stations it returned was KKTU. KKTU changed its call sign to KDEV on March 31, 2005 and again changed to KQCK on June 17, 2008. Makes one wonder where the FCC is pulling its info from.
post #5 of 20
I noticed one glitch right away, too.

It shows WTOL with their highly directional "appendix B" pattern, even though they've been granted a CP to go omnidirectional with their existing channel 11 antenna.
post #6 of 20
I punched in my location just to see what is there. Numbers match pretty closely with tvfool. Gain/loss map was wrong for one of the stations (KFXP out of Pocatello, ID).
post #7 of 20
Rather optimisitic - there's no way I can get anything but the green and yellows (some).
post #8 of 20
this thing is inaccurate for me. It has 7.1 in yellow, thats the strongest station I get, as well as WZMY DT 50.1 (35). I get that one too.

Everything else seems correct.
post #9 of 20
The results seem reasonable for my CA location. As for Mystic, CT, WEDH is missing (not even listed as no signal) but otherwise it seems ok. WEDH comes in ok most of the time, with some weather dropouts.
post #10 of 20
It's 50/50. I get two it says I should have no signal. Again, I think terrain is difficult to calculate. TV Fool is a better guesser.
post #11 of 20

I've been playing with this for awhile now. It is really easy to "drag and drop the marker", as DrBri99 said. Addictive to TV DXing nerds

I do notice that it does respond to terrain (evident when dragging the marker through the lakes and hills around Sleeping Bear Dunes, MI).

Its station list for Temperance, MI (truly flat terrain) is DEAD ON. Using a CM 3020 at about 35', WBGU and most Detroit stations (49-52 miles away) truly are "yellow" (perfectly reliable, provided the antenna is pointed on the right direction). WKBD is correctly predicted "orange" (works with the antenna when directly plugged into the TV, but not strong enough to pass through a VCR too). WADL is correctly "red" (in much of the time during the summer, depends on tropo to be seen).
post #12 of 20
Thread Starter 
Originally Posted by Scooper View Post

Rather optimisitic - there's no way I can get anything but the green and yellows (some).

The web site is showing the post-transition allotments and may be using older non-maximized allotments at that. So you have to look at each station that the calculation shows is different from what you expect and see if the station will be changing channels, etc.
post #13 of 20
Originally Posted by afiggatt View Post

The web site is showing the post-transition allotments and may be using older non-maximized allotments at that. So you have to look at each station that the calculation shows is different from what you expect and see if the station will be changing channels, etc.

I have NEVER gotten a wiff of the Roanoke VA stations (admittedly, they were listed as red), as well as most other out of market stations. I also optimized my antenna selection for just my local stations, so that has some effect, I'm sure.

What's strange is that when conditions are just right - my DTVPALs will pickup enough of a Richmond and Norfolk station (and some long range southern NC stations) to get them listed in the channel list - of course, in the morning they don't come in any more.
post #14 of 20
Some notes about the system:

1) It uses the parameters from the application the station designated as their post-transition facility on their form 387. In other words, we rely on the stations to have filled out a form correctly. There are some cases where the form is incorrect. (thanks itsthemultipath!) We're looking into fixing the system on a case-by-case basis when from 387 doesn't agree with reality, but it's not possible to manually verify the parameters for 1800+ stations, so if you notice something, let me know (PM me). This system does not take the last-in-time application if there is a Form 387 on file (which is what TVFool appears to do) because this is often NOT the appropriate post-transition facility.

2) It uses 1km terrain sampling, whereas TVFool uses 100m terrain sampling. This was done for speed of the system (which as you can see is already slow enough). This doesn't make a difference for most people, but if you're in the type of terrain where a hill can be completely erased by 1km terrain sampling, then it's going to be overly optimistic.

3) It uses the exact same algorithm as TVFool, the "ILLR" algorithm. The colors are slightly different. I'm not sure what their thresholds are, but on the FCC one, red is below the band-dependent reception threshold listed in the rules and DTV planning factors. Orange is 0-15dB above that. Yellow is 15-35 db above the threshold, and green is >35dB above the threshold.

4) As a general rule of thumb, indoor antennas should be able to receive green stations, attic antennas should be able to receive yellow stations, rooftop antennas are necessary for orange stations, and red stations will require a very large highly directional rooftop antenna. Of course, your mileage may vary, especially on indoor antennas.
post #15 of 20
I tried this tool and it has reasonable results for my southeastern CT location except that it is missing WEDH-DT. I checked the gain/loss map for WTNH and it shows yellow dots around my area. What exactly is this meant to show? Is it the change in coverage between the old analog and new digital signals? If so does it include interference from other stations? I am wondering if it is showing the loss of WTNH coverage in my area caused by the adjacent WEDN-DT channel.
post #16 of 20
I dont get a listing for WEDH either. It should be similar in strength to WTIC. I think the gain/loss are an attempt to show gained of lost locations when going from analog to digital. My experience is that the VHF analog coverage area is realistic but depends on how much snow is acceptable. The UHF digital coverage is very optimistic and any station switching from analog VHF to digital UHF loses much more ground than shown in the maps.
Based on what I can receive here the the comparitive predicted levels can be off by 10 to 15 dB.
post #17 of 20
We have found a workaround for the database issues that were causing many of the errors. WEDH should now appear with its correct parameters. Please let me know if you notice any other stations that are missing entirely.

The gain/loss maps show the areas where signal was either gained or lost, relative to the analog coverage. Green dots indicate gained signal, Red dots indicate lost signal, and Orange dots indicate that signal was lost but another station of the same network provides service to that are. The maps will be updated with legends later today.

Thank you for all of the feedback.
post #18 of 20
So when there is a discrepancy between what you actually receive, and with they (and TVFool.com) predicts, who do you contact? Or how do you get the TV station to fix their problem?

I have no problems receiving WFFF, WCAX, WPTZ, and PBS from Mt. Mansfield. However, I cannot receive WVNY more than 50% of the time.

I have top-end equipment, and I've eliminated as many problems as possible.

Here is my TVFool plot. And here are the FCC plots for WVNY.

Who can fix the problem with WVNY? The station engineers are no help. I've tried.

I've contacted the FCC, and they gave the standard response, get a better antenna, check your connections, etc. Been there, done that. I can receive WMTW on VHF-8 (analog), but I can still receive a signal with a station that weak!. I can receive WFFF-DT 100% of the time, no problems, but WVNY supposedly has a stronger signal.

See here for my setup.


post #19 of 20
My results surprisingly are spot on. All my channels I receive are listed, right through the 0range ones.

The ones that say "No Signal" are right too. WRAL, WTVD, WNCN, WRAZ, WLFL and WRDC
post #20 of 20
It's pretty accurate for my area. The only problem is that some virtual channels are showing up as the RF channel number.
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