ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3 4   Go Down

Author Topic: RF Interference at Stadium  (Read 2346 times)

Dan Dollar

  • Newbie
  • *
  • Offline Offline
  • Posts: 6
RF Interference at Stadium
« on: September 07, 2019, 10:56:30 am »

Hi, I work for a school district and we're having issues with our ref mic and rf interference. We have 2 paddle antennas pointed down at the field on the top floor where the press boxes are. I've scanned for different channels and it just says "full". My questions is how to NFL teams do this? I'm assuming they have some sort of mobile rig they wheel out including the antennas to field level. Then that signal goes to the main mixing board. Anybody have any idea about this? Pictures would be much appreciated. Should we consider upgrading the mic receiver? Thanks!
Logged

Mac Kerr

  • Old enough to know better
  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6878
  • Audio Plumber
Posting Rules
« Reply #1 on: September 07, 2019, 11:18:20 am »

Hi, I work for a school district

Please go to your profile and change the "Name" field to your real first and last name as required by the posting rules displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section, and on the registration page when you registered.

Mac
admin
Logged

Jason Glass

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 784
    • CleanWirelessAudio.com
Re: RF Interference at Stadium
« Reply #2 on: September 07, 2019, 05:46:33 pm »

Hi, I work for a school district and we're having issues with our ref mic and rf interference. We have 2 paddle antennas pointed down at the field on the top floor where the press boxes are. I've scanned for different channels and it just says "full". My questions is how to NFL teams do this? I'm assuming they have some sort of mobile rig they wheel out including the antennas to field level. Then that signal goes to the main mixing board. Anybody have any idea about this? Pictures would be much appreciated. Should we consider upgrading the mic receiver? Thanks!

Hi Dan,

I'm a part-time NFL frequency coordinator and my main business is RF systems engineering and technical work for entertainment productions.

Are you the AV Tech at Wylie Independent School District in TX?  If so, you're not going to like some of the news.

Your antenna locations on the press box are pretty much standard for referee mics in stadiums all around the world, and should function fine if your equipment is of decent professional quality, all of your coaxial cables are in good condition, and none of your components are corroded from outdoor moisture.

TV stations around DFW changed their frequencies and channel numbers on June 21 to conform to new FCC rules regarding radio spectrum in the UHF TV band.  You are most likely now the unhappy operator of newly obsolete equipment that can no longer be used near Dallas.  Your scans are probably showing full because the frequency range that the system is capable of using is now completely occupied by TV stations.  If that is the case, then you must cease operating that system immediately.

The graphic below shows the current UHF TV spectrum in Dallas as it applies to wireless microphone use.  When you acquire your new systems, make sure that they are capable of tuning in the frequency ranges shown in the white slots below.  As an unlicensed "Part 15" equipment user, you would be wise to avoid the bands shown above 600 MHz.  They are subject to restrictions that make certain portions of them legal only for "Part 74" licensed operators.

Alternatively, you could opt for systems that operate in the less-crowded VHF TV band, such as the Shure ULX-D bands V50 or V51.  This would require replacing your antennas with much larger VHF antennas.  Avoid systems that operate in ISM bands such as 902-928 MHz and 2.4 GHz because they're unreliable for professional use.

If you're in a bind and must rent gear quickly for upcoming games, Dallas has several great sound companies that do short-term rentals of wireless mics.  VER usually has systems on-hand, as does Onstage Systems (formerly Dallas Backup).  You can plug your existing antenna cables right into the rentals to get up and running easily.
« Last Edit: September 07, 2019, 05:59:12 pm by Jason Glass »
Logged

Dan Dollar

  • Newbie
  • *
  • Offline Offline
  • Posts: 6
Re: RF Interference at Stadium
« Reply #3 on: September 08, 2019, 05:52:13 pm »

Hey Jason. Thanks for the response. I had known about the 600mhz selloff but it didn't occur to me that whatever was occupying the 600mhz had to move to the 4/500s until you said that. Definitely makes sense now since last year was fine but it just started this school year. Can you tell me which make and model mics you use when you do work for the nfl?
Logged

Kevin Maxwell

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1347
Re: RF Interference at Stadium
« Reply #4 on: September 08, 2019, 06:54:12 pm »

Hey Jason. Thanks for the response. I had known about the 600mhz selloff but it didn't occur to me that whatever was occupying the 600mhz had to move to the 4/500s until you said that. Definitely makes sense now since last year was fine but it just started this school year. Can you tell me which make and model mics you use when you do work for the nfl?

What do you have now? Is it tune able to some of the holes Jason shows in his attachment?
Logged

Jason Glass

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 784
    • CleanWirelessAudio.com
Re: RF Interference at Stadium
« Reply #5 on: September 08, 2019, 07:05:05 pm »

Hey Jason. Thanks for the response. I had known about the 600mhz selloff but it didn't occur to me that whatever was occupying the 600mhz had to move to the 4/500s until you said that. Definitely makes sense now since last year was fine but it just started this school year. Can you tell me which make and model mics you use when you do work for the nfl?

At events that large, there are dozens to hundreds of different entities that bring their own equipment, and it varies widely.  As frequency coordinators, we work with all of them to accommodate just about every wireless system that there is, from toy garbage to top of the line professional.

Due to professional obligations, I can't disclose information about or recommend NFL-preferred systems or how we use them.

However, I can comment based on my other work in athletic stadiums and the equipment that their AV staff use.  In USA, for high priority channels such as ref mics, the overwhelming preferences seem to be Lectrosonics and Axient Digital.  I would include analog Axient, since many are still in use, but it is obsolete and superceded by AD.

Dan Dollar

  • Newbie
  • *
  • Offline Offline
  • Posts: 6
Re: RF Interference at Stadium
« Reply #6 on: September 08, 2019, 08:09:25 pm »

Right now we have the Shure SLX4/SLX1 in the 518-542mhz range. When we had our 1st game most every channel said it was full but one of few that didn't, still didn't work. I'll have to do some more testing tomorrow. We do have some QLXD gear in the district that I can borrow to do a scan and maybe use for a game. Maybe then I can find an open frequency. If it still doesn't work I'm going to suggest an upgrade considering it's been at least 5-7 years since this equipment was installed. Thanks
Logged

Kevin Maxwell

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1347
Re: RF Interference at Stadium
« Reply #7 on: September 09, 2019, 12:24:09 am »

Right now we have the Shure SLX4/SLX1 in the 518-542mhz range. When we had our 1st game most every channel said it was full but one of few that didn't, still didn't work. I'll have to do some more testing tomorrow. We do have some QLXD gear in the district that I can borrow to do a scan and maybe use for a game. Maybe then I can find an open frequency. If it still doesn't work I'm going to suggest an upgrade considering it's been at least 5-7 years since this equipment was installed. Thanks

I just tried to find 4 channels for Shure SLX wireless mics (in the H5 band 518.200-541.800) at zip code 75098 into the latest version of Shure Wireless Work bench (WWB). I assumed that that should be all that you will need but I may be wrong. And I got the following frequencies that should work at your location assuming I have the Zip code right. This is with using the TV look up at 50 miles and only high powered stations. The RF environment doesnít look good for 75098 if you include low power stations that should be far enough away , the closet one looks like it is 22.6 miles away from you and shouldnít interfere with you.
G:06 Ch:11 ,540.325 MHz - G:06 Ch:08, 536.250 MHz - G:02 Ch:08, 532.575 MHz - G:06 Ch:02, 520.400 MHz

Keep in mind that in general the strongest thing at the receiver wins. I would be sure that the referees donít turn their wireless mics off that they just mute them. There may be other factors that are giving you problems but if you have a chance try and see if these frequencies work. BTW one of the factors that could cause you trouble is if they havenít yet turned off their old TV transmitters when they mode to the new frequencies. I think they could get into a lot of trouble if they have left them on.
Logged

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6067
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: RF Interference at Stadium
« Reply #8 on: September 09, 2019, 04:18:06 am »

Right now we have the Shure SLX4/SLX1 in the 518-542mhz range. When we had our 1st game most every channel said it was full but one of few that didn't, still didn't work. I'll have to do some more testing tomorrow. We do have some QLXD gear in the district that I can borrow to do a scan and maybe use for a game. Maybe then I can find an open frequency. If it still doesn't work I'm going to suggest an upgrade considering it's been at least 5-7 years since this equipment was installed. Thanks

Isn't this amazing Dan, where else on the Internet would you get access to the support you are receiving.  You could work your entire career in this business and never get the opportunity to work with someone of Jason's pedigree.  As for Kevin doing the WWB work for you, well that was awesome too.  You owe these guys some beers.

Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Jason Glass

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 784
    • CleanWirelessAudio.com
Re: RF Interference at Stadium
« Reply #9 on: September 09, 2019, 08:53:23 am »

G:06 Ch:11 ,540.325 MHz - G:06 Ch:08, 536.250 MHz - G:02 Ch:08, 532.575 MHz - G:06 Ch:02, 520.400 MHz

In that list of freqs, only 520.400 is currently reliability usable outdoors near Dallas, in reference to TV broadcast.

At this time, the Key Bridge database utilized by WWB is untrustworthy for TV allocations.  Spectrum analysis such as that shown in my second attachment is always more reliable.  However, 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=
« Last Edit: September 09, 2019, 09:31:40 am by Jason Glass »
Logged

ProSoundWeb Community

Re: RF Interference at Stadium
¬ę Reply #9 on: September 09, 2019, 08:53:23 am ¬Ľ


Pages: [1] 2 3 4   Go Up
 



Page created in 0.062 seconds with 22 queries.