Seeking Transmitter Information..

[ButtnPushr]

I'm not sure if this is the right forum for my question, but here goes: Do Drive-In Movie Theaters require an FCC license to broadcast on FM radio? I was at a drive-in recently and was wondering about the broadcast requirements. The movie that was playing had lots of swear words in it and I wondered if the FCC could monitor that frequency. We left after the first movie and while the second played I could still pick up the audio over a mile away. What are the rules for small transmitters like that? Do they require a license? And could someone complain about the language and get them shut down? Just wondering. Thanks.

 

[317C50KW]

If their power is more than 100milliwatts (100mw) they should be licensed in a perfect world.

But obviously 100mw won't cover a drive in theatre, football stadium. indoor sports arena or anywhere else where the venue as a courtesy would like to provide wireless transmission to prospective users.

There was some talk of "special event" licenses for limited specific short term use. That may be on the books, it may have been just talk.

Of course there a places in the spectrum where the theatre would not need licensing, IIRC the 2.8 and 5.4 ghz ballpark. Do you have a receiver that can get those frequencies?

It sounds like the theatre is in violation. Whether the FCC would find this something they would want to investigate is another question.
Their role as a spectrum compliance watchdog has slowly de-evolved over the years. And it shows.

 

[Lancer]

I've heard of that also & wondered the same thing. They may think their transmitter is in compliance (if they care) but don't consider the external antenna which would give it a substantial boost.

 

[bradgoehl]

If this helps you... I think they likely are running under Part 15, and with the proper antenna and both it and your car being outdoors its entirely possible to hear it that far away and still be legal especially if they have several operating in multiple locations around there property.


Section 15.319 General technical requirements.
(a) [Reserved]
(b) All transmissions must use only digital modulation techniques.
(c) Peak transmit power shall not exceed 100 microwatts multiplied by the square root of the emission bandwidth in hertz. Peak transmit power must be measured over any interval of continuous transmission using instrumentation calibrated in terms of an rms-equivalent voltage. The measurement results shall be properly adjusted for any instrument limitations, such as detector response times, limited resolution bandwidth capability when compared to the emission bandwidth, sensitivity, etc., so as to obtain a true peak measurement for the emission in question over the full bandwidth of the channel.
(d) Power spectral density shall not exceed 3 milliwatts in any 3 kHz bandwidth as measured with a spectrum analyzer having a resolution bandwidth of 3 kHz.
(e) The peak transmit power shall be reduced by the amount in decibels that the maximum directional gain of the antenna exceeds 3 dBi.
(f) The device shall automatically discontinue transmission in case of either absence of information to transmit or operational failure. These provisions are not intended to preclude transmission of control and signaling information or use of repetitive codes used by certain digital technologies to complete frame or burst intervals.
(g) Notwithstanding other technical requirements specified in this subpart, attenuation of emissions below the general emission limits in Section 15.209 is not required.
(h) Where there is a transition between limits, the tighter limit shall apply at the transition point.
(i) Unlicensed PCS devices are subject to the radio frequency radiation exposure requirements

 

[TexasTom]

There's a lot of erroneous technical information in this thread...

First, the 100 mw limit applies to Part 15 on AM, not FM. An unlicensed FM station running 100 mw is violating FCC rules and runs the risk of being shut down.

Second, those rules that were quoted are most definitely not for unlicensed operation in the FM band, but appear to apply to digital operations in some other bands (I'm guessing that they may apply for the bands used by Wi Fi services and the like, but don't know for sure).

The limit for operation in the FM band is that your field strength at three meters from the transmitting antenna may not exceed 250 microvolts/meter. That's puny power and minimal range -- you wouldn't cover more than a fraction of a drive in theater with that little power. To get around this, a drive in theater that is operating legally would used a so-called "leaky cable" system -- the cable can snake all around the drive in theater, and as long as the 250 microvolt/meter limit is met at three meters from the cable, it is perfectly legal. It's also the only legal alternative -- the FCC does not license drive in theaters...

My suspicion is that a fair number of drive in theaters will just set up an illegal transmitter and not mess with the legal niceties, though.

 

[MikeShannon914]

What's a drive-in theater? ;D

 

[ChuckTiller]

What's a drive-in theater? ;D

LMAO

 

[rbrucecarter5]

My suspicion is that a fair number of drive in theaters will just set up an illegal transmitter and not mess with the legal niceties, though.

Isn't there a special "performance" license for temporary transmitters? I seem to remember something about that for Orlando stations that didn't have a good signal broadcasting temporary low power stations on Daytona Beach. If there is, maybe that is the authority under which the drive-ins operate.