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RF frequencies ... (MHz): 300, 315, 390, 433 ...what else ?

Discussion in 'Electronic Design' started by Rodo, Jul 15, 2005.

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  1. Rodo

    Rodo Guest

    Hi all,

    I know these frequencies are used by wireless devices like clocks,
    temperature sensors, garage openers, etc. Is there any other that could be
    used ?

    Thanks
     
  2. mc

    mc Guest

    A huge variety. Look up Code of Federal Regulations, Title 47, Parts 1 and
    15, especially the latter.

    I assume you're in the United States. If not, there are even more
    possibilities.
     
  3. John Larkin

    John Larkin Guest

    The range [DC:daylight] is available.

    John
     
  4. Guest

    These applications fall under low-power part 15. So, there is no real
    what to know what freq a low power device will use.

    If there is an FCC ID number on the cover, you can use it to look at
    the FCC database. I have done this several times and found very useful
    information, including schematics and tech service manuals.

    Now some folks, aka Radio Shack do not provide any documetation

    Europe is limited to 418 MHz in the UK, 433.92 MHz and double the
    433.92 for the next freq. And that is it.

    U.S. just lets the manufacture select the frequency and it could even
    be in the FM broadcast band.

    One Garage Door Company works on 390 MHz. Very little used frequency
    just on the edge of 400MHz which is for government military and
    controlled by NIST.

    A nice government "phone cell" clone project appear on 405MHz at Eglin
    AFB. The thought is that this system will be placed at every base site
    in the United States.

    The 1000 erp power station completely blanked out garage door receivers
    for over 40 miles.

    The GDO company came down and found out about the interference from the
    government. The item was brought up that they had been on 390 MHz
    since the beginning (20 years) and would have expected a freq study to
    have been done before the final frequency range was selected.

    And, the company expected that the government would have came out with
    a notice to manfacturers. This company did a study and determined that
    over 100 million openers would be impacted.

    The case was bought up that the US government should allocate freq
    bands for this type service, a 1 MHz spread that could be called home.

    The comment was that if GDO get a band, then every other peanut powered
    intenional radiator producer would want a piece.

    Ol well, spelling getting bad, it late....

    pdrunen
     
  5. Joel Kolstad

    Joel Kolstad Guest

    They already have them, don't they? The various ISM bands at 49MHz, ~900MHz,
    ~2.4GHz, ~5.8GHz, etc. I think what you're really saying is that they want a
    _protected_ band, which would be difficult to find for every little interest
    out there.

    In this particular case, -- at least from what's been presented -- it does
    seem that the military should have paid a little more attention to commercial
    users at 390MHz. Perhaps a better alternative would have been for them to set
    up a, say, 5-10 year schedule after which they'd glom onto the band -- giving
    the GDO manufacturers time to get better filtering in place, switch bands,
    etc.
     

  6. The rules state that unlicensed use in those bands do not have
    priority, and must accept interference from licensed services. Any
    military use that leaves the installation where it is used has to notify
    the FCC. AFRTS radio and TV stations are issued a "license". The one
    I worked at in Alaska had a radio and a TV station, and both were
    recognized by the FCC.

    I used to repair the transmitters and receivers for a "Overhead Door
    Company" dealer in Ohio and the equipment was very poorly designed.
    Single conversion, tone modulated and broad as a barn. Take a look at
    what is in the transmitter and receiver these days. It is still the
    cheapest junk they can build to open the door from 25 feet.

    --
    Link to my "Computers for disabled Veterans" project website deleted
    after threats were telephoned to my church.

    Michael A. Terrell
    Central Florida
     
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