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433MHz remotes with >500ft range

Discussion in 'Electronic Design' started by Joerg, Oct 29, 2010.

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  1. Jamie

    Jamie Guest

    Talking from experience are we?
  2. TutAmongUs

    TutAmongUs Guest

    This is where a number of folks insult you... and your mother... and
    your little dog too!

    You are about as utterly brainless as a person can get, and you claim
    to be mature and educated. That claim is truly hilarious, and pathetic.
  3. warm'n'flat

    warm'n'flat Guest

    Perhaps I should qualify that. It certainly did when I was in Florida
    20 years ago.
  4. warm'n'flat

    warm'n'flat Guest

    On Tue, 02 Nov 2010 18:39:37 -0700, TutAmongUs
    Another silly nym for your list, Michael.
  5. warm'n'flat

    warm'n'flat Guest

    Sorry, I haven't seen that one before.

    What's the score now? Not that a list is necessary. Nymbecile's posts
    are easily recognised.
  6. Jamie

    Jamie Guest

    You must still be on the sauce, you don't get it! ;)
  7. You are still in the barrel, dog piss mouth.

    Qualify? Bwuahahahahahahahaha!
  8. TutAmongUs

    TutAmongUs Guest

    Simple proof that he is about as stupid as one can get. But hey, the
    dumbfuck reads your pathetic horseshit, so it is a given that he is a
    total retard.

  9. Mouthy Mikey Picks and Chooses whom he wishes to mouth off at directly.

    In other words, the motherfucking wuss is too pussified to banter with
    real men. Even those he chooses to spat upon are far better than he.
    Merely by the fact that he does it (insult) to those he has chosen to be
    a fucking mouthy putz toward.

    Good job, Micheal. NOT!
  10. warm'n'flat

    warm'n'flat Guest

    Care to repeat that rubbish? In English this time, please.
  11. Jeez, it doesn't get much more wussified than a spelling lame and the
    third person dialog... again.

    Bwuahahahahahhahahaha! You're a joke, T E R R E L L

    Did I spell that one right, ASSWIPE?
  12. warm'n'flat

    warm'n'flat Guest

    Lurn tu spel Nymbecile. It's ARSEWIPE
  13. Joerg

    Joerg Guest

    Can't get into details but think "farm" or "golf course" :)

    AFAIK they simply used its alarm clock function, at least that's what
    our morning paper reported.
  14. From propagation point of view, those are quite a bit different

    At 150 m and 433 MHz, the free space loss is less than 70 dB, so even
    if the transmitter power is less than 10 mW (+10 dBm) to remain within
    international standards, the receiver power would be -60 dBm, i.e. a
    very generous signal at least compared to thermal noise from the
    receiver itself or the surroundings.

    However, this assumes free space propagation, which should not be too
    hard to achieve with one antenna in a high place on a golf course.
    Some light vegetation (bushes) should not cause much problems on 433

    However, golf courses are typically locating within a short driving
    distance from population centers, so if the receiving antenna is in a
    high place, it will pick a lot of signals from other non-licensed
    devices in the band, making it impossible to predict a reliable
    communication range. The situation with a single transmitter high up
    and the receivers close to ground is easier, since the terrain will
    somewhat block distant signals.

    The situation on a farm in the middle of nowhere is quite different,
    you usually do not have to worry about other emitters on the band, so
    a receiver high up in the air should not suffer. However, large
    concrete or metallic structures often found on a farm, will cast a
    shadow, if you are just behind it.

    You need to specify the environment more accurately or take the worst
    case of both the farm and golf course example to determine the
    reliable range in an unspecified environment.
  15. Joerg

    Joerg Guest

    This assumes a full-blown antenna though which is usually not possible
    or desired. Mostly it's the "rubber duckie" kind, meaning another 10dB
    or so drop.

    This is something that at least in the US we don't have to worry much
    about. We live on a hill with the high-gain antenna pointing towards
    Silicon Valley. No problem to listen to signals from there yet the 70cm
    ham band is almost deserted. Not much going on there.

    Non-licensed signals are quite weak and a good hopping scheme can get
    around that. Problem is, most remotes aren't that smart.

    Way to deal with that is, for example, FHSS. As long as the receiver
    won't choke in the presence of strong signals and that's what I find to
    be a rather sore point with modular designs. There I'd rather design my
    own. But not the remote, that should come pre-certified and all. The
    challenge that this presents is that many FHSS schemes are kept secret,
    for whatever reason.

    That is what we'll have in most cases, some sort of building the signal
    has to go through. Or bounce around and get there on a secondary path
    with a lot less amplitude.

    Sure, but first I'd have to find a viable solution. Then we'll try it
    out in the field. The solution requires most likely finding a good
    quality remote with full documentation, then a matching chip set to
    build a receiver around that. I'd really like to design my own receiver
    because my experience with commercial modules is, let's say, rather "mixed".
  16. Use a diversity receiver and several strategically located antennas.
  17. Joerg

    Joerg Guest

    I know, but in this case we don't want to drive the effort quite that
    far :)
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