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Author Topic: RF Interference at Stadium  (Read 2337 times)

Kevin Maxwell

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Re: RF Interference at Stadium
« Reply #10 on: September 09, 2019, 09:09:15 am »

In that list of freqs, only 520.400 is currently reliability usable outdoors near Dallas.

At this time, the Key Bridge database utilized by WWB is completely untrustworthy for TV allocations.  Spectrum analysis such as that shown in my second attachment is always more reliable.  However, we must still heed the databases channel exclusions for public safety radio systems.

Thank you for that information. Can you tell me why the Key Bridge database is untrustworthy. When I talked to Shure about a month or two ago they said that some of the repack was still unsettled as to where some TV stations were moving to. I sounded like it was an FCC issue.
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Jason Glass

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Re: RF Interference at Stadium
« Reply #11 on: September 09, 2019, 09:42:29 am »

Thank you for that information. Can you tell me why the Key Bridge database is untrustworthy. When I talked to Shure about a month or two ago they said that some of the repack was still unsettled as to where some TV stations were moving to. I sounded like it was an FCC issue.

Key Bridge, like most radio frequency allocation info services, relies on raw data published by the FCC.

We can only speculate as to why the info is, and has been for a very long time, unreliable.  One can easily point to uncertainty about LPTV reallocations, but this problem predates that issue by years.  Although it was far better before the repack and is right now in utter shambles.  IMHO, the most likely reason is that the commission is like every other federal bureaucracy at this time; underfunded, understaffed, and underskilled.
« Last Edit: September 09, 2019, 09:49:30 am by Jason Glass »
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Kevin Maxwell

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Re: RF Interference at Stadium
« Reply #12 on: September 09, 2019, 10:01:51 am »

Key Bridge, like most radio frequency allocation info services, relies on raw data published by the FCC.

We can only speculate as to why the info is, and has been for a very long time, unreliable.  One can easily point to uncertainty about LPTV reallocations, but this problem predates that issue by years.  Although it was far better before the repack and is right now in utter shambles.  IMHO, the most likely reason is that the commission is like every other federal bureaucracy at this time; underfunded, understaffed, and underskilled.

I donít mean to make this tread stray but I have a question that maybe you can answer. I was under the impression that part of this whole reallocation was supposed to discourage some of these Low Power TV stations by changing the way the must carry requirement worked. The cable companies would still be required to carry them even though they would no longer be transmitting over the air and taking up bandwidth. But it seems like they all wanted to still have a channel to broadcast on, even though there may only be a handful of people actually watching them over the air. 
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Jason Glass

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Re: RF Interference at Stadium
« Reply #13 on: September 09, 2019, 10:57:09 am »

I don’t mean to make this tread stray but I have a question that maybe you can answer. I was under the impression that part of this whole reallocation was supposed to discourage some of these Low Power TV stations by changing the way the must carry requirement worked. The cable companies would still be required to carry them even though they would no longer be transmitting over the air and taking up bandwidth. But it seems like they all wanted to still have a channel to broadcast on, even though there may only be a handful of people actually watching them over the air.

This is still in the realm of my humble opinion.  The commission failed to adequately anticipate the financial and political power of many of the entities that own LPTV stations, who would much rather have low income viewers watching OTA for free and tithing or purchasing trinkets with their $ rather than paying a cable or satellite TV bill.  Cable TV isn't even deployed to many rural areas, including my neighborhood, which is only 30 miles from a metropolis.  They also failed to acknowledge that the numerous non-English-language LP stations provide legitimate public service to significant portions of our communities, which is supposed to be a high priority in the commission's work.  They overestimated the total data bandwidth in the UHF band available for high definition content (preferred by all broadcasters over SD) and underestimated the financial and commercial difficulties that LP stations would face in leasing bandwidth on co-channel transmitters owned by their competitors.
« Last Edit: September 09, 2019, 11:01:27 am by Jason Glass »
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Dan Dollar

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Re: RF Interference at Stadium
« Reply #14 on: September 09, 2019, 12:44:53 pm »

You guys are awesome. I tested again today and placed the slx on 520.400 mhz channel. The wireless pack was still terrible. I tried the handheld and it was a lot better but still had some static. I was able to borrow a qlxd and I was able to walk every inch of the field with no dropouts. I think I'm going to recommend an upgrade to digital in a frequency range with more available channels. I appreciate your help so much!
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Kevin Maxwell

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Re: RF Interference at Stadium
« Reply #15 on: September 09, 2019, 10:47:41 pm »

This is still in the realm of my humble opinion.  The commission failed to adequately anticipate the financial and political power of many of the entities that own LPTV stations, who would much rather have low income viewers watching OTA for free and tithing or purchasing trinkets with their $ rather than paying a cable or satellite TV bill.  Cable TV isn't even deployed to many rural areas, including my neighborhood, which is only 30 miles from a metropolis.  They also failed to acknowledge that the numerous non-English-language LP stations provide legitimate public service to significant portions of our communities, which is supposed to be a high priority in the commission's work.  They overestimated the total data bandwidth in the UHF band available for high definition content (preferred by all broadcasters over SD) and underestimated the financial and commercial difficulties that LP stations would face in leasing bandwidth on co-channel transmitters owned by their competitors.

Is this issue of not being able to trust the Key Bridge database something that will get straightened out once the repack is finalized? What is the best way to handle this at the present time? Even though a scan of a room shows hardly anything being received from outside I still like to use the database look up so I know I am safer. I have been told that I am being too paranoid but what if they really are out to get me?  ;) 
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Jason Glass

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Re: RF Interference at Stadium
« Reply #16 on: September 10, 2019, 12:08:42 am »

Is this issue of not being able to trust the Key Bridge database something that will get straightened out once the repack is finalized? What is the best way to handle this at the present time? Even though a scan of a room shows hardly anything being received from outside I still like to use the database look up so I know I am safer. I have been told that I am being too paranoid but what if they really are out to get me?  ;)

We can only hope that the database administrators will eventually get their act together.  Key Bridge must somehow collect revenue from somewhere for their services, which will surely fade away if their product remains crap for the end user.  Unless Uncle Sam foots the bill.  Then it could go on being garbage for a long time.  I don't know if Shure pays them fees for integration into WWB, and it doesn't appear that there's much of a white space devices industry large enough to support them at this time.

...we must still heed databases channel exclusions for public safety radio systems.

It's always wise to cross-reference your WWB or IAS database query returns with another source such as https://www.rabbitears.info/repackchannels.php?country=US&city=&state=&mktid=5&owner=&sort=&ph=&lss=&status=

After starting a coordination with my above suggestions, your on-site spectrum analysis or scans should be used in combination with that data.  It's worth noting that the rules allow RF mics on an active TV channel that has measured signal strength lower than -84 dBm at the mic TX operating location.  That includes indoor locations shielded by structural materials.

Henry Cohen

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Re: RF Interference at Stadium
« Reply #17 on: September 10, 2019, 01:29:40 pm »

Currently, the best FCC database to use for determining occupied channels is the Licensing and Management System. Data is presented in a different format than the TV Query database, but it is mostly up to date.

By far the best TV database tool set available right now is rabbitears.info which draws on all the FCC databases and provides a wealth of repack and phase transition information.

However, nothing beats an actual RF scan of the target location at the time of deployment. Barring a real time scan, one that is somewhat recent, and not prior to a transition phase end date is the next best thing. There are a couple of very good scan repositories available:

- Peter Erskine's bestaudio.com (registration is required, but only to keep out the riff-raff, there is no tracking or advertising, well no tracking Pete's aware of . . .)

- Gotham Sound

- For Manhattan, NY, by far the best resource is rfcoordinationnyc.com. Pauls' scans are immediately post each phase deadline (his last scans are August 1) and are in the general areas of the primary TX points in Manhattan.

As it concerns whitespace databases, Nominet is another currently active database in which Part 74 licensees can ostensibly register for protection. There is no confirmation of registration and very little additional information. It does not inspire confidence.
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Henry Cohen

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Kevin Maxwell

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Re: RF Interference at Stadium
« Reply #18 on: September 13, 2019, 12:23:13 am »

You guys are awesome. I tested again today and placed the slx on 520.400 mhz channel. The wireless pack was still terrible. I tried the handheld and it was a lot better but still had some static. I was able to borrow a qlxd and I was able to walk every inch of the field with no dropouts. I think I'm going to recommend an upgrade to digital in a frequency range with more available channels. I appreciate your help so much!

I tried a coordination using Jasons chart of the TV channels to avoid and came up with a few frequencies that the software is telling me should work. This is all theoretical without a scan of the environment we really can't be sure.

520.500 - Grp 2 ch 2
522.225 - Grp 2 ch 3
518.425 - Grp 6 ch 1
523.425 - Grp 6 ch 3

I don't know if you are still trying to make this work and if this is of any help to you.
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Don Boomer

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Re: RF Interference at Stadium
« Reply #19 on: September 13, 2019, 07:13:00 pm »

However, nothing beats an actual RF scan of the target location at the time of deployment.

True dat!  And probably more important with every day into the future. Life is gonna get tough in the very near future for those that canít get a good co-ordination.
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Don Boomer
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Re: RF Interference at Stadium
¬ę Reply #19 on: September 13, 2019, 07:13:00 pm ¬Ľ


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