Guidelines for stadium/arena transmitters

[HurricaneRun]

Does anyone know of any guidelines for in-arena FM broadcast? I know that they are present in virtually every pro and college venue but I have been unable to find any FCC rules about these broadcast.

HR

 

[Chuck]

> Does anyone know of any guidelines for in-arena FM
> broadcast? I know that they are present in virtually every
> pro and college venue but I have been unable to find any FCC
> rules about these broadcast.

They come under Part 15 rules. Those rules are a little different for AM or FM, but Part 15 is still where you look for guidance. As far as I know compliance is based on field strength of 15 micro volts per meter, which is measured 3 meters away from the radiating element. In the case of an educational facilities campus, the FCC has generally allowed those field strength measurements to be taken at the perimeter of the campus, rather than from the radiating element. That is pretty easy to comply with and still have good coverage in the building.

For non-educational facilities, I think very few of these systems actually comply with the rules although some may come close. Some use a "leaky coax" that runs around the inside perimeter of the building. That’s probably the closest to “by the book” you can do, but it is costly to install. The theory is that low level RF can be picked up throughout the seating area where the coax cable can be routed. Because the building is usually made of steel reinforced concrete and steel beams, there is usually very little radiation outside the building. That's probably why the FCC turns a blind eye to these things.

I've also seen systems with a single radiating antenna mounted in the roof, fed by a small transmitter. Those usually are in the 1-1.5 watt range. Decade, in Canada makes a transmitter specifically for the purpose. I think LPB still markets them too.

Even though these probably don't follow the exact letter of the law, it is reasonable to think that in reality they cause very few problems. They usually are only operated during an event, and properly set up, it is doubtful that they would cause any harmful interference.

That said, I've heard of several venues that have had their systems shut down for noncompliance. These are usually outdoor facilities like race tracks, etc. Unwanted radiation is more of a concern in such an installation.

I wish the FCC would actually codify and approve the use of special event FM transmission systems. Running in the 1-2 watt range on a temporary basis, they could be extremely useful.

 

[radio8z]

> Does anyone know of any guidelines for in-arena FM
> broadcast? I know that they are present in virtually every
> pro and college venue but I have been unable to find any FCC
> rules about these broadcast.
>
> HR
>
Hi,

There are no "guidelines" for this just as there are no "guidelines" about speed limits, but there are rules as specified in Part 15.

There are special considerations for educational institutions which are not avaliable to the "civilian" broadcasters but they apply to AM and not FM.

I disagree with those who say that the FCC will turn a blind eye to FM transmissions simply because they are originating on a campus or in a stadium. If you violate the rules, then you are exposed to enforcement action. From what I have read this enforcement does not consider programming, venue, or intent. It simply follows from a technical interpretation of part15 rules which for FM limits the field strength to 250 microvolts/meter at 3 meters from the antenna.

My advice is that you should read the part 15 rules regarding FM (15.239). Once you have done this I am sure many on this board will answer specific technical questions you may have.

Neil

 

[JasonW]

When I worked at the Miami Space Transit Planetarium (home of "The Star Hustler," Jack Horkheimer of PBS TV fame), we had a Ramsey FM transmitter in the theater for Spanish translations of the star shows. Spanish-speaking guests were issued fixed-tuned walkman radios, and the signal covered the entire interior of the metal dome very well (I guess you could call it an artificial ionosphere).

The signal could be heard outside the dome, but no farther than the back workshop about 15 feet away. -- JasonW

> > Does anyone know of any guidelines for in-arena FM
> > broadcast? I know that they are present in virtually
> every
> > pro and college venue but I have been unable to find any
> FCC
> > rules about these broadcast.
>
> They come under Part 15 rules. Those rules are a little
> different for AM or FM, but Part 15 is still where you look
> for guidance. As far as I know compliance is based on field
> strength of 15 micro volts per meter, which is measured 3
> meters away from the radiating element. In the case of an
> educational facilities campus, the FCC has generally allowed
> those field strength measurements to be taken at the
> perimeter of the campus, rather than from the radiating
> element. That is pretty easy to comply with and still have
> good coverage in the building.
>
> For non-educational facilities, I think very few of these
> systems actually comply with the rules although some may
> come close. Some use a "leaky coax" that runs around the
> inside perimeter of the building. That’s probably the
> closest to “by the book” you can do, but it is costly to
> install. The theory is that low level RF can be picked up
> throughout the seating area where the coax cable can be
> routed. Because the building is usually made of steel
> reinforced concrete and steel beams, there is usually very
> little radiation outside the building. That's probably why
> the FCC turns a blind eye to these things.
>
> I've also seen systems with a single radiating antenna
> mounted in the roof, fed by a small transmitter. Those
> usually are in the 1-1.5 watt range. Decade, in Canada
> makes a transmitter specifically for the purpose. I think
> LPB still markets them too.
>
> Even though these probably don't follow the exact letter of
> the law, it is reasonable to think that in reality they
> cause very few problems. They usually are only operated
> during an event, and properly set up, it is doubtful that
> they would cause any harmful interference.
>
> That said, I've heard of several venues that have had their
> systems shut down for noncompliance. These are usually
> outdoor facilities like race tracks, etc. Unwanted
> radiation is more of a concern in such an installation.
>
> I wish the FCC would actually codify and approve the use of
> special event FM transmission systems. Running in the 1-2
> watt range on a temporary basis, they could be extremely
> useful.
>

 

[w9wi]

> I wish the FCC would actually codify and approve the use of
> special event FM transmission systems. Running in the 1-2
> watt range on a temporary basis, they could be extremely
> useful.

They have, under experimental authorizations:

"FM STATION APPLICATIONS FOR EXPERIMENTAL STATION ACCEPTED FOR FILING
--------------------------------------------------------------------

LA BPEX-20020131ABW WN2XFL 136592 GLOBAL RADIO, INC. Experimental FM application for event radio service on
93.7 MHz, 96.1 MHz, 99.9 MHz, 100.7 MHz, 101.5 MHz, and 103.7 MHz
P 93.7 MHZ NEW ORLEANS, LA A"

(from Feb. 6, 2002 "Broadcast Applications". Remove the "2X" - present in all experimental callsigns - and you know who was behind this operation!)

 

[Chuck]

>
> They have, under experimental authorizations:

True, but those are few and far between, requiring quite a bit of preparation on the part of the applicant. For special circumstances, you can get a STA in a reasonable amount of time, but most people needing this service this never go through the process and either go pirate, or don't do it at all.

In a previous life, I was in the sound reinforcement business. We had many occasions where a client would ask us for some such use on a daily rental basis. We never did it because there was never enough time enough to deal with the Commission, but the idea has always intrigued me.

One concert promoter wanted us to do a "Walkman Concert" at an outdoor amphitheater style venue. The idea was the audience would bring their walkmans, and listen to the concert broadcast directly to their headphones. I would have loved to do something like that. Instead, we used an normal 50,000 watt PA system and got noise complaints from the homes that were located nearby.

There are plenty of applications where this kind of service would be very useful and a watt or so would be all it takes to make it work well.

 

[radio8z]

New license class for this?

> >
> > They have, under experimental authorizations:
>
> True, but those are few and far between, requiring quite a
> bit of preparation on the part of the applicant. For
> special circumstances, you can get a STA in a reasonable
> amount of time, but most people needing this service this
> never go through the process and either go pirate, or don't
> do it at all.
>
> In a previous life, I was in the sound reinforcement
> business. We had many occasions where a client would ask us
> for some such use on a daily rental basis. We never did it
> because there was never enough time enough to deal with the
> Commission, but the idea has always intrigued me.
>
> One concert promoter wanted us to do a "Walkman Concert" at
> an outdoor amphitheater style venue. The idea was the
> audience would bring their walkmans, and listen to the
> concert broadcast directly to their headphones. I would
> have loved to do something like that. Instead, we used an
> normal 50,000 watt PA system and got noise complaints from
> the homes that were located nearby.
>
> There are plenty of applications where this kind of service
> would be very useful and a watt or so would be all it takes
> to make it work well.
>


Hello all,

Interesting post. Maybe the FCC would consider a new license class for sound enhancement or emergency activities modeled after the amateur radio service in the respect that a licensed person could use a 1 watt transmitter at any suitable location and on any suitable FM broadcast frequency on a temporary basis. Though amateurs have station licenses, they are permitted to operate "mobil" under authority of the license.

Just a thought.

Neil

 

[ironbear]

Re: New license class for this?

> Hello all,
>
> Interesting post. Maybe the FCC would consider a new
> license class for sound enhancement or emergency activities
> modeled after the amateur radio service in the respect that
> a licensed person could use a 1 watt transmitter at any
> suitable location and on any suitable FM broadcast frequency
> on a temporary basis. Though amateurs have station
> licenses, they are permitted to operate "mobil" under
> authority of the license.
>
> Just a thought.
>
> Neil

Always the leader, Canada has just such a classification built around 1 Watt transmitters, but with a field strength limitation at the boundry of the property it's located on, although th operators are apparently civic authorities and businesses.

 

[Chuck]

Re: New license class for this?

> > Hello all,
> >
> > Interesting post. Maybe the FCC would consider a new
> > license class for sound enhancement or emergency
> activities
> > modeled after the amateur radio service in the respect
> that
> > a licensed person could use a 1 watt transmitter at any
> > suitable location and on any suitable FM broadcast
> frequency
> > on a temporary basis. Though amateurs have station
> > licenses, they are permitted to operate "mobil" under
> > authority of the license.
> >
> > Just a thought.
> >
> > Neil
>
> Always the leader, Canada has just such a classification
> built around 1 Watt transmitters, but with a field strength
> limitation at the boundry of the property it's located on,
> although th operators are apparently civic authorities and
> businesses.
>
It seems to simple. The compamy or person who has a license to do this would serve in the same manner that the SBE Frequency Coordinators do. It is not a big stretch. The hardware and software already exist. You don't have to reinvent the wheel.

In my previous business, I would have done whatever it takes to qualify and be a responsible operator. The public would gain a valuable service, and the vendor could provide responsible use of the airwaves. I really don't see a large downside to this idea, as long as it is done responsibly.

 

[CW]

> Does anyone know of any guidelines for in-arena FM
> broadcast? I know that they are present in virtually every
> pro and college venue but I have been unable to find any FCC
> rules about these broadcast.
>
> HR

Part 15 rules....you could use radiating Heliax (Radiax) with a high power transmitter and dummy load at the end to cover every section of the stadium...BUT you cannot exceed Part 15 radiated levels at any point...