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Discussion Starter #221

Quote:
Originally Posted by mattdp /forum/post/14183618


-Are we going with raw transmitter power or ERP with beam tilt? I assume raw ERP.


-KWNO 99.3 is listed as having an ERP of 7.15KW, when the only FCC record I can find says 11KW.


-KHME 101.1 is listed as having a 1.72KW ERP, when the only FCC record says 5KW.


-WHWC 88.3 is listed as having an 29.46KW ERP, when the only FCC record says 70KW.

When you look at the FCC records, what you see is the peak ERP plus some antenna pattern data. In reality, you will never find a broadcaster that directly pushes out that much raw power (looking at the electric bill). They always rely on some amount of gain from their transmit antenna (usually in the range of 10-24 dB) to achieve the peak ERP values granted by the FCC. A "1000 kW broadcaster" might only have about 15 kW of real power feeding into the antenna. The FCC lists effective power levels after factoring in the antenna, but only at the highest gain point in the antenna pattern.


Depending on the transmitter's antenna pattern and your location, the effective radiated power being directed at you might be less than the peak ERP. The transmit powers you see in the TV Fool reports have been adjusted according to the antenna patterns on file with the FCC.


For each of the stations you mentioned, we have the correct peak ERP levels in our database, but you are probably seeing a smaller value in your reports due to their respective antenna patterns.


As you can imagine, the accuracy of the signal analysis is absolutely dependent on having the correct adjusted ERP for each transmitter.



Quote:
-HD Radio Icons: A pretty accurate and up to date list is available at hdradio.com.


-RDS Icons: http://www.rdslist.com/ is about the best I can find.


-FMeXtra: As you may know, this is alternative technology to HD Radio. Here is about the best list I can find: http://en.wikipedia.org/wiki/FMeXtra#USA I e-mailed FMeXtra to see if they had or knew where to find a good list of US stations carrying the service.


-Also.... I think it would be helpful to have some system where we could propose changes to a given entry. Some system where you could enter in the call letters of a station, then it would come up with a page with two collums. One would have existing info, and the other would be entry boxes for new data, etc... Below these fields, you could have a text entry box where one could cite reasons or sources for the changes.


For example, somebody could subit a proposed change, such the station's broadcasting in RDS. The text entry box could provide either a person's statement that he indeed picked up RDS on the station, or it would point to a web page with proof of this. You could hit a button and update the proposed the changes to the database. Same could go for TV networks, database errors, etc....

I'm familiar with the hybrid digital radio data (terrible marketing gimmick, causing confusion with high definition). I'll look into the rest.


Best regards,

Andy
 

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Ooooooh..... now it makes sense. I was looking through the FCC database and finding that most of your entries were close, but never right on target with their ERP.


There are a few TV stations, however, that I think you have the CP entries on.


How exactly do I find the polar pattern for TV stations? The "service contours" I look at are all perfectly round.
 

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Discussion Starter #223

Quote:
Originally Posted by Falcon_77 /forum/post/14178618


How are you handling the application filings? I noticed that WNAC is showing the 30kW ND antenna that they want, while WPRI still shows the existing 18kW license (they also requested 30kW).

This has to do with whether or not we've created an FCC "override" to fix some error in the original FCC records. In the case of WPRI, we had a "patch" that is now being superseded by new records that are hopefully more up-to-date and accurate than ours. In order for the new records to show up correctly, I had to remove the record from our collection of FCC fixups.


This takes care of WPRI, but if you notice any other records that have the same problem, please let me know.


Best regards,

Andy
 

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Quote:
Originally Posted by mattdp /forum/post/14189483


How exactly do I find the polar pattern for TV stations? The "service contours" I look at are all perfectly round.

These can be found on the FCC TV database query. Here is an example for KXLT, which has directional patterns. Look for the polar plot link and table.

http://www.fcc.gov/fcc-bin/tvq?list=0&facid=35906


Non-directional stations don't have them as they are (theoretically) the same ERP at every azimuth.
 

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Discussion Starter #225

Quote:
Originally Posted by mattdp /forum/post/14189483


How exactly do I find the polar pattern for TV stations? The "service contours" I look at are all perfectly round.

Many broadcaster use omni antennas which will have a perfectly round radiation pattern, however, for those broadcasters that are using directional antennas, you should see a table plus hyperlink for the "Relative Field polar plot".


BTW, the FCC service contours are very rough estimates of coverage. They do not take into account detailed terrain obstructions. Their main value to the FCC is to check for "interference keep-out zones" when reviewing applications for transmitter construction, for which these rough estimates are good enough.


Best regards,

Andy
 

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Quote:
Originally Posted by mattdp /forum/post/14189779


Alright.... after testing everything through the polar pattern, I sill managed to find a few entries that might need to be double checked:

Note that the polar plots are based on voltage ratios. In order to get a directional ERP from the graph you square the voltage ratio at that azimuth and multiply by the maximum ERP.


ERP = ERPmax * Vsquared
 

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On a log scale it's 20*log() for voltage instead of 10*log() for power (like coax loss). Maybe that's too deep, but compare the Relative Field Polar Plot against the Service Contour Map (41 dBu). http://www.fcc.gov/fcc-bin/tvq?list=0&facid=35906


For the dBu plot (which is logarithmic), note how the upper left quadrant is "squished" and the lower right "tail" is expanded compared to the polar Field plot. The service contour might be easier to use as a reference for TV Fool's signal levels, which are in dBm (also logarithmic). For comparing 'dB' things, it might help to see the pattern shape a bit better. Not as a coverage reference, just the overall shape. That's over-simplified, but I think it might be easier for those who have trouble understanding 'dB' stuff.
 

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WHYY-DT's current configuration appears to be mis-filed in the FCC database (i.e. it is not with the other WHYY records filed under facility ID 72338, and it's not clear to me why) here:

http://www.fcc.gov/fcc-bin/tvq?facid=165726


Their proposed post-transition configuration is where it should be, the 2nd and 3rd records (1st record is current WHYY analog configuration) here:

http://www.fcc.gov/fcc-bin/tvq?facid=72338


Looking at the respective antenna patterns, it looks like the 9.9 KW configuration will use the current analog antenna, while the 20 KW configuration will use a new antenna with a reduced signal strength to the northwest, for whatever reason. In any case, the current digital antenna with its problematic (for me, anyway) null to the northeast will be outa here.


My question concerns the transition timing... namely: When will the 9.9 KW configuration go online, vs when will the 20 KW configuration go online?
 

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Discussion Starter #231

Quote:
Originally Posted by frank70 /forum/post/14427783


WHYY-DT's current configuration appears to be mis-filed in the FCC database (i.e. it is not with the other WHYY records filed under facility ID 72338, and it's not clear to me why) here:

http://www.fcc.gov/fcc-bin/tvq?facid=165726

Unless someone reports a problem to the FCC database maintainers, they probably don't realize that there's a problem. This particular transmitter had to be patched by TV Fool's local database of corrections.

Quote:
Looking at the respective antenna patterns, it looks like the 9.9 KW configuration will use the current analog antenna, while the 20 KW configuration will use a new antenna with a reduced signal strength to the northwest, for whatever reason. In any case, the current digital antenna with its problematic (for me, anyway) null to the northeast will be outa here.


My question concerns the transition timing... namely: When will the 9.9 KW configuration go online, vs when will the 20 KW configuration go online?

The 9.9 KW construction permit was granted on 2/15/2008 and is flagged as a post-transition facility. The 20 KW application for a minor modification to the construction permit was filed 6/20/2008, but there's no indication yet if it was or will be granted. If the 20 KW application is granted, then I'm guessing that on February 18, they will simply turn on the 20 KW configuration, bypassing the 9.9 KW configuration.


I'm just speculating, but if you contact the station engineers, or local people in-the-know, you might get a more authoritative answer.


Best regards,

Andy
 

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Discussion Starter #232

Quote:
Originally Posted by mattdp /forum/post/14427955


What happened to Andy? He hasn't responded to a post on this thread since late June.

Hahaha...


Work's been keeping me busy. If you must know, I've been traveling to Washington DC a few times over the last month and haven't had a whole lot of spare time to stop by.


Best regards,

Andy
 

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Discussion Starter #233

Quote:
Originally Posted by mattdp /forum/post/14189779


Alright.... after testing everything through the polar pattern, I sill managed to find a few entries that might need to be double checked:


-KYIN-DT


-WHWC-DT


-WQOW-DT

OK. I'll look into it. What do you suspect is wrong with these transmitters?
 

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Low ERP compared to their current record.


Also... the dead K280EL entry is still kicking around on FMFool, and I have a few minor corrections in post #219 that have yet to be addressed.


There's a big translator farm in another part of the state that re-broadcasts a number of Twin Cities stations. I can hook you up with a guy who receives them, so he can give you the correct networks and subchannels.
 

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Get this... The TVGOS and TitanTV listings for WNJS-DT subchannels 3, 4, and 5 disappeared as of September 1. An email to the station got a reply that they discontinued 3,4,5 as of September 1, and now only have subchannels 1 and 2. Their RF channel is 22, and I've confirmed that 22.3, 22.5, 22.6, and 22.7 (corresponding to PSIP channel mappings 23.1, 23.3, 23.4, and 23.5) are all still broadcasting (albeit, not all at the same time, 23.3 SD yields to 23.5 HD in the evenings.) Furthermore, 23.2 (RF 22.4) still comes up with no-signal as always. How can they say they've made a change when clearly they haven't?


Also strange is that on their website, the programming listed for what they call NJNDT2 does not correspond to anything being broadcast on the 4 subchannels mentioned. Yikes, did someone make an executive decision, and then forget to tell the engineering department?


UPDATE: Spoke with Mr. Williams of NJN engineering today and apparently there really was a misunderstanding within the organization as to when the change-over was going to occur. Engineering says October (waiting for some equipment), while the department in charge of TV listings presumed September 1. At least now they're aware of the problem, though they don't seem committed to fix it.


Apparently, the goal is to finally start looking like most other stations; i.e. having 23.1 be HD 24/7, with 23.2 being SD. But it ain't there yet, so it certainly is confusing in the interim.
 

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About the antenna height option. Is this suppose to be above sea level? I get way more accurate results when I use my above sea level elevation then I actually give and elevation of the antenna above ground elevation. Seems like it would have to be above sea level since topography is not accounted for. Any ideas? Thank you.
 

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Well, I thought they did account for local terrain. From the FAQ:
Quote:
The signal strength from each of the broadcasts is analyzed for your location using 3D propagation modeling algorithms, and the results are summarized in the plot and table. Transmitter power, terrain obstructions, Earth curvature, and your antenna height (if specified) are already factored into the report.
 

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the value above ground is only as good as the data they use. if they get USGS map data while good in general it can be only a course general contour.


if you knew your actual height above sea level at the antenna site then that would probably be more accurate.
 

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If I used the above sea level number for my antenna, TVFool would give very optimistic results. The TVFool calculations assume the number entered for antenna height are above ground level. A 5000 foot antenna height would give me ridiculous results.
 

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I obviously missed the note about TVFOOL using terrain in the calculations.


The reason I asked was because where my parents live they get many, many more channels then what TVFOOL shows at ground level. When we factored in the height above sea level (with GPS) around 1600 feet TVFOOL showed the rest of the stations that they pick up.


Are there any other sites that do this? I've tried antennaweb too but it is worthless IMO.
 
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