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Radio Transmitters - Legal Power regulations

Discussion in 'FM Transmitters' started by AussiePhil, Jun 7, 2010.

  1. AussiePhil

    AussiePhil Dedicated Elf Administrator

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    In keeping with the international audience, the actual legal rules around power levels allowed for unlicensed FM broadcasting vary from country to country. I am attempting to find regulations for each of the Major countries an if people can point me to a web page or PDF i will edit this post and update.

    This post is to provide you with the actual regulations governing the use of FM transmitters for un-licensed broadcasting. Please advise of any changes, amendments or out right mistakes with links to the original regulations.

    First off USA...
    Title 47--Telecommunication
    --------------------------------------------------------------------------------
    CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
    PART 15--RADIO FREQUENCY DEVICES
    15.239 Operation in the band 88–108 MHz.
    (a) Emissions from the intentional radiator shall be confined within a band 200 kHz wide centered on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88–108 MHz.
    (b) The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 microvolts/meter at 3 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. The provisions in § 15.35 for limiting peak emissions apply.
    (c) The field strength of any emissions radiated on any frequency outside of the specified 200 kHz band shall not exceed the general radiated emission limits in § 15.209.

    what's the above mean.. here's a simple read, http://www.gate.net/~advradio/fcc.html

    Australia...
    From
    Radiocommunications (Low Interference Potential Devices) Class Licence 2000

    Class Licence
    (1) This Class Licence authorises a person to operate a transmitter included in a class of transmitters mentioned in item in Schedule 1, subject to the following conditions:
    (a) the transmitter must be operated:
    (i) on a frequency, or within a range of frequencies, mentioned in
    the item; and
    (ii) at a radiated power that does not exceed the maximum EIRP
    mentioned in the item; and
    (iii) within the limitations (if any) mentioned in the item;
    (b) the transmitter’s operation must not cause interference to the operation
    of radiocommunications services.
    -----------
    Schedule 1 Transmitters
    Item 21: Wireless audio transmitters and auditory assistance transmitters
    Freq: 88-108 Mhz
    Max EIRP: 10uW
    Limitations
    1. Emission must be frequency modulated and have a maximum bandwidth of 180 kHz.
    2. Transmission in a radio channel must not originate in the licence area of a radio broadcasting station (including a repeater or translator station) operating in the same channel.

    -----------------------------------------------

    See the wikipedia for EIRP http://en.wikipedia.org/wiki/Equivalent_isotropically_radiated_power

    -----------------------------------------------
    Others, please let me know

    Phil
     
  2. Dave

    Dave Full Time Elf

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    Pardon my ignorance here Phil,

    Coming from a lay man, I really only need to transmit for about 100-200m (a strong signal in that range, i realise the further away the weaker the signal). Without going into the maths, i was looking at a .5 or .25 watt transmitter. Do we need a licence to transmit within this range?
     
  3. OP
    OP
    AussiePhil

    AussiePhil Dedicated Elf Administrator

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    Simple answer is yes..... you will get 3-4km's with a .5W (i know) and is quite definately outside the allowed power under the rules.

    Not so simple answer is that many people run 50mW and 100mW ones and never get a visit from the Radio inspectors...
    Phil
     
  4. joelrose

    joelrose NW Iowa

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    Less technical American version

    If A car radio can pick it up further than 200 foot.
    YOU ARE NOT LEGAL.

    http://www.fcc.gov/mb/audio/lowpwr.html

    PART 15 DEVICES

    Unlicensed operation on the AM and FM radio broadcast bands is permitted for some extremely low powered devices covered under Part 15 of the FCC's rules. On FM frequencies, these devices are limited to an effective service range of approximately 200 feet (61 meters). See 47 CFR (Code of Federal Regulations) Section 15.239, and the July 24, 1991 Public Notice. On the AM broadcast band, these devices are limited to an effective service range of approximately 200 feet (61 meters). See 47 CFR Sections 15.207, 15.209, 15.219, and 15.221. These devices must accept any interference caused by any other operation, which may further limit the effective service range. For more information on Part 15 devices, please see OET Bulletin No. 63 ("Understanding the FCC Regulations for Low-Power, Non-Licensed Transmitters"). Questions not answered by this Bulletin can be directed to the FCC's Office of Engineering and Technology, Customer Service Branch, at the Columbia, Maryland office, phone (301) - 362 - 3000,

    Joel
     
  5. Dave

    Dave Full Time Elf

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    My FM transmitter arrived on Friday, found a power supply and connections required, hooked it all up tonight and hey presto.
    With the aerial inside i went for a drive and have excellant reception for 500m in 1 direction and 800m the other. Pretty happy with that.

    Dave
     
  6. dbuckley

    dbuckley New Elf

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    New Zealand rules

    Read all about it here: [link], a page on the Radio Spectrum Management website.

    Short version: there are about 20 fixed frequencies at the top and bottom of the broadcast FM band available (though with some limitations in differing parts of the country), and you can run 1W e.i.r.p. which is quite generous compared to most other countries.
     
  7. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Great info for you kiwis out there and very generous tranmission output. Thanks for posting that info and link
     
  8. Steve22537

    Steve22537 Full Time Elf

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    Wouldn't it make sense for the "mobile audience" if everyone tried to use the same frequency with a lower output, except in the situation of multiple transmitters interfering with one another.

    Steve
     
  9. OP
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    AussiePhil

    AussiePhil Dedicated Elf Administrator

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    Steve

    I actually agree with you but not always possible with a lot of people using low power transmitters for many things including whole house audio.

    I drove around my area at my choosen frequency to check for anyone else already using it. Certainly within one area we should all try to select a common frequency.

    Phil
     
  10. Robbo

    Robbo Full Time Elf

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    That would be quite helpful for the people who are aware of radio transmitted shows and know where they are but don't have to keep changing channels, noone else near me that would be doing a radio transmitted show....I doubt anyone visiting Beacy would be visiting me in the same night...20-30 minutes apart
     
  11. geoff

    geoff New Elf

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    ive been using the original fordray fm transmitter with the lightorama mp3 controller for a few years now & the range is only about 80 metres before it starts to drop.
    however as fordray have updated the basic model i believe the new 1 has a switch to either keep it local or make it powerful ( illegally powerful).

    as long as it doesnt interfere with other things i dont think anyone has much to worry about.
    if you used the powerful mode then your problems would start.

    i think the bigger concerns with our displays is all the amateur electricians!!!! lol
     
  12. tuppetsdad

    tuppetsdad Funding & Tech Support

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    Re: Radio Transmitters

    We bought an FM transmitter from China for $50 and really it was the easiest thing we have set up. Just plug in turn on and set the frequency. We just picked a frequency which was not used locally and seems like we get around 200 meters broadcast range which works well. Have left Christmas carols running 24/7 so probably our neighbors are a bit bored..... ::)
     
  13. kel

    kel Dedicated Elf

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    details, pls ... as in brand, model number, etc




    ($50 ... and legal ... omG!)
     
  14. JonB256

    JonB256 Full Time Elf

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    I had one of those $50 bargain transmitters 3 years ago. It didn't make it through testing. Luckily, ??, it died with time to find a Ramsey FM25B before show time.

    When it worked, it was great. Then it began to overheat (blistered my finger), then it died (no smoke though).

    I look at the EDMs occasionally. Since I have two friends who also do lights locally, I've recently considered getting the EDM and leaving the Ramsey as our emergency spare. We all use the same frequency, so it would be ready to go.
     
  15. Robbo

    Robbo Full Time Elf

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