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RFID or Magnetic Sensor for Detection up to 6ft? — Parallax Forums

RFID or Magnetic Sensor for Detection up to 6ft?

mtbphil1mtbphil1 Posts: 6
edited 2009-02-06 17:16 in BASIC Stamp
I created a lap timing system last summer for bike racing using a sonar sensor to detect the rider passing.· It worked ok, but I'd like to replace the sensor with a more robust and reliable method using RFID or magnetic field detection.· What is the best sensor option for dectection up to 6ft (finish line width), and can someone recommend a sensor that easily interfaces with the stamp? I've only found RFID for 12" or less or a hall effect sensor that doesn't seem to be the right choice.···The·final component I need is an RF transmitter/reciever pair for at least 1000ft.· I've searched the web and found some products, but if possible I'd like to use products with some documentation on how to interface with the STAMP.· Any help on direction to the right sensors and RF products for easy STAMP interfacing would be appreciated!

Comments

  • bdbbdb Posts: 30
    edited 2009-02-06 17:00
    I'm not totally up on the subject, but am doing some playing around with RFID myself and wonder if the two items below may be helpful to you.

    As I understand it, the RFID in the hobby kits are at a very low frequency (125) and can only read from a short distance.· There are commercial units at higher frequencies that can read from a greater distance (and are used in libraries, stores, etc).

    Back when I did running, some running events had chips that you would tie to your shoe.· Used for getting the exact time when you crossed the start line and when you cross the finish line.· These were usually used for very large events.· But the running community may be able to tie you in with whoever they get to sponsor them.

    Good luck.
  • UghaUgha Posts: 543
    edited 2009-02-06 17:16
    Do you have to be able to tell one rider from another? Because that's the main reason to use RFID.

    Why not use infrared "beams" that the riders break as they pass?

    If you really need to ID each rider as they pass, then you can use an IR LED beacon on each bike that'll pulse at different frequences for each rider.

    You'd need to setup a software filter to account for sunlight and the like, but it shouldn't be too hard to setup using very inexpensive parts and a BS2.

    The only problem would be if two riders passed side by side.
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