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RFID (revisited)

Discussion in 'Electronic Design' started by [email protected], Jun 30, 2005.

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  1. Guest

    I did a group search for RFID tags, and found nothing recent, or
    relevant. Maybe the state of the art (cost) has changed, and somebody
    knows something.
    I would like to place a tag on a telephone pole every mile that could
    be read as the train goes by to confirm location. The tag could be
    powered by battery/solar in order have enough poop to make the ~30 foot
    Any suggestions?

    As I think about it, maybe I could just mount a tiny transmitter that
    chirps out a quick data burst every so many seconds, and use a little
    receiver on the train to interpret the data. Since xmtrs are a mile
    apart, there won't be interference, and the short burst might make the
    battery run it OK. (the train goes no faster than 25 mph).

    This will probably evolve into too many variables and not enough
    equations ;=)

  2. Jim Thompson

    Jim Thompson Guest

    SAVI Technologies makes exactly what you want...

    ...Jim Thompson
  3. Joel Kolstad

    Joel Kolstad Guest

    Unfortunately, although RFID is a very active area right now, a lot of it is
    done under non-disclosure/private contracts/etc. so you won't find as much
    about it on the web as you might expect.
    Ummm... can't you just put a GPS receiver on the train and it'll always know
    where it is? Or where you looking to somehow link your sensors together so
    that, shortly after the train passes by a given pole, that fact is
    communicated to a control center/database/whatever some distance away?
    Usually the variable that becomes difficult to solve for is the one
    representing money. :) What kind of budget were you thinking?

    ---Joel Kolstad
  4. if Jim's sugestion is too turn key, Atmel has tags that you can suff in the NEMA box of your choice. Even listed in Digikey.

  5. Andy

    Andy Guest

    Andy writes:

    The TIRIS toll tag system uses reflective backscatter and
    has a range of greater than 30 feet.

    The TAG would be on the pole and the ILLUMINATOR would
    be on the train. TAG battery life would be on the order of
    5 years.

    AMTEL also makes a similar system. However, the AMTEL
    tag is on continuously, and may not have as long a battery life,
    tho I am not certain what they claim.

    However, the GPS suggestion which a respondent posts later
    in this thread is a great idea. It is used by many many transportation
    agencies, and will have much less cost, as well as not requiring
    any maintenance on telephone poles. Many railroads do not have
    telephone poles, anyway --- that stuff is moving underground....

    If you are bound and determined to use an RFID tag, I suggest
    you do a search on SAVI, TIRIS, MARK6 , and SIRIT .

    Lots of info available from these companies.

    Andy ( formerly principal engineer of TIRIS for
    Texas Instruments in a previous life )
  6. Jim

    Jim Guest

    I seem to remember a system where the RFID tags were attached to the RR
    tracks at known locations and when the RR went over it, the Tx in the RR
    triggered the passive tags and they sent an ID back to the train.

    This system, using passive tags, will last a heck of a long time, and with
    the tag so close to the Tx, there is plenty of power to activate the tag.

    So, I'd forget the phone poles, burying the tags inside the RR tracks will
    protect the tags, and use a standard Tx to interrogate them.


    Granted, GPS and a link back to the Hq makes more sense in general, you
    could have the system auto dial a cellphone and send it's location and time
    once an hour, or as often as desired.

  7. Pooh Bear

    Pooh Bear Guest

    Considering how cheap a GPS receiver is these days, surely that *has* to be the
    best option ?

    Over here, Woolworths are selling a GPS based 'speed trap detector' for a mere
    £80 that includes the first years worth of database updates !

    It has a GPS data output to connect to a PC / laptop too.

  8. PeteS

    PeteS Guest

    At the risk of some flameage, we (among others) make turnkey tracking
    solutions (uses GPRS to report data from GPS amongst other things).
    Note we're in the UK. I know there are outfits that do this in the
    states, though.


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