Do you have any recommendations about placing a radio frequency identification reader within a car that could alert a driver if an RFID transponder on a bicycle or pedestrian came within a certain range (perhaps 25 feet)? It would be very simple, because the reader would only need to determine location. So could I get something like this cheaply?
I don't think RFID would be the appropriate technology for this application. For it to work, you would need to somehow get all pedestrians and bike riders to wear RFID tags, which I can't see everyone doing voluntarily.
In addition, it would not be easy to determine an object's location within the read field of a conventional ultrahigh-frequency (UHF) RFID reader. Distance is ascertained using a received signal strength indicator (RSSI). The signal strength can be affected by environmental conditions. So if it were raining, it might not be possible to read a tag from 25 feet away. What's more, if there were metal under the pavement, you might get a reflection of the radio waves that could affect the ability to determine distance in unpredictable ways.
Active tags broadcast a signal, and it might be possible to create a system that could determine distance more accurately—but such a solution would be expensive. Buying a tag for every pedestrian at a cost of $10 or more apiece would be very costly, indeed.
—Mark Roberti, Founder and Editor, RFID Journal
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