Fastrak autopsy

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P914 writes –

When my Fastrak tag stopped working, I decided to risk losing my $20 deposit in the name of science. It turns out that they open pretty easily by prying around the edges with a flat blade screwdriver. I posted a few photos to Flickr so everyone can see what these look like inside. Maybe someone else knows more about RFID and can explain how the circuit works?

Fastrak autopsy (photos) – Link.

14 thoughts on “Fastrak autopsy

  1. I’ve worked with these systems in the past, and am familiar with similar systems used in N.Y. N.J, Boston, Georgia, and California.

    Most of these transponders support an “Industry Standard” protocol, as one or more propietary ones. For the most part, the industry standard is avoided to make it more difficult for the customer to migrate to a competitor’s hardware.

    Each toll lane has a lane controller pc with serial ports and DIO ports for communicating with the transponder reader, gates, signs, etc. The transponders operate in passive-active mode, so they usually require the antenna in the toll lane to send an unattenuated signal to turn on the tag. When the tag turns on, it attenuates the signal, encoding is serial number, and checksum back to the lane controller.

    The reader unit is also in a passive-active state controlled by magnetic loops in the road, or in some cases, ir light curtains.

    Seriously, Electronic Toll Systems are lot of fun to work on.

  2. Oh, I almost forgot! The tags have a life expectancy of 5 to 7 years, on average. I modded one to work off solar that a vendor provided in a clear case (ours were black or green).

  3. The battery is in fact dead. Before now I had always assumed these were powered by the reader and had no internal battery, but I guess the piezo buzzer gives it away. This one lasted about 4 years.

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