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Author Topic: RF in north america  (Read 1583 times)

Pete Erskine

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RF in north america
« on: January 03, 2016, 04:33:20 pm »

This was an email sent to me on pro Sound and the writer has agreed to share it.

Quote
Hello Pete,

My name is Sapna Patel. I hope you are well and had a good holiday season. I don't know if this is bad etiquette contacting you directly on a forum as I'm not really used to being on these. But I heard you were one of the best people to ask about things related to RF. And I have read a few of your articles.

I am a freelance RF technician in the UK. I mostly do award shows and festivals in the UK but I'm getting out more. I did a few weeks in N. America last year with One Direction and its seemed straight forward enough but I wanted to investigate a bit more into what is the correct procedure over there and wondered if you could advise me or point me in the right direction.

I tried calling the FCC but maybe I spoke to the wrong department or asked the wrong questions to get a simple answer.

It seems shows with small RF channel counts (I mostly deal with radio mics and IEMs) can turn up and scan and plot frequencies anywhere that's free between about 500-700MHz excluding channel 37... But you can apply for a license if you want to book channels to protect yourself from white space devices. Do you happen to know if this is widely practiced yet? Or if the RF channel count is above 50 they recommend licensing channels anyway.

I guess what I really want to know is if WSD are having a big impact on the kind of work we do over there yet? Do you happen to know anyone who has toured out there that has reported any issues yet?

Any advice would be greatly appreciated!

Thanks,
Sapna Patel

Currently, before the sale of of the 600 mHz band, rf in the USA is not too hard.  I personally have not come in contact with white space devices.  Maybe other users can share where they have.

Watch the James Stoffo video on coordination in the current RF spectrum situation, on this forum for some details on what might happen and how you can avoid any problems.

I have not had an event where I needed to register or license to use the white space database.  The main coordination issue is staying away from receivable DTV stations, mostly because your RF wont work very well but Legally the spaces they use must be protected.

I say receivable because often within a venue the OTA DTV transmissions are shielded and the spectrum might be usable if you are desperate for more space.  I start always by assuming the worst and even if I am inside I use the outside scan as my base.  Even if you cannot see a DTV carrier inside it surely is increasing the noise floor in any case and better to avoid if you can.

I have been collecting inside/outside scans around the worly so you can look at these to see what kind of shielding may be possible.  Go to http://www.bestaudio.com/spectrum-scans/




« Last Edit: January 04, 2016, 06:16:59 pm by Pete Erskine »
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Pete Erskine
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Henry Cohen

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Re: RF in north america
« Reply #1 on: January 03, 2016, 09:12:08 pm »

Sapna,

To elaborate on Peter's response, the US operates differently than the UK (and most other EU countries for that matter) with regards to PSME spectrum allocations. First, there are maybe two or three people at the FCC (all in the Office of Engineering Technology) who actually come close to understanding the work flows and types of entities when it comes to wireless microphones and similar devices. The call center operators have no idea who to even send you to. But fear not; you found a great resource in these forums.

Secondly, FCC licenses are not issued on a per event basis; rather they are issued for three, then seven year terms to those persons/entities meeting certain eligibility requirements. What wireless mic users can do - currently both unlicensed and licensed until after our 600MHz auction, then just licensed users - is register in the white space geo-location database(s) to obtain  interference protection from WSD's/TVD's at the time(s) and location(s) specified. Basically, registering in the database simply removes those TV channels from the WSD/TVD availability pool. It offers no protection from any other type of user, nor is it any type of coordination process.

As far as coming up against WSD's/TVD's in the field, fixed base type devices are showing up in convention centers and stadiums. We've experienced and had reports both from other coordinators and the NFL about WSD/TVD installations [done improperly as they apparently were either not connected to the geo-location database. or had the incorrect coordinates programmed in]. There are currently no personal/portable products in the market place.

As for the rest of Peter's comments, all very sound advice, as usual. And his Best Audio web site is a fantastic resource.
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Henry Cohen

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Sapna Patel

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Re: RF in north america
« Reply #2 on: January 06, 2016, 05:33:13 pm »

Hello,

Thank you both for your advice. I have looked into the geolocation databases more and it seems to make sense. Apparently one of the administrators even does an app! Although looking at some venues its seems a complete RF nightmare in some places.

Thank you for the link to the Best Audio website!

Sapna
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ProSoundWeb Community

Re: RF in north america
« Reply #2 on: January 06, 2016, 05:33:13 pm »


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