We are looking to put RFID sensors in a safety vest for workers on outdoor job sites containing heavy machinery. We want machine operators to know, to within about 10 feet, where all personnel are located on the ground for safety measures. What type of sensors would be needed, and how many would we need for each garment?
I would recommend an ultra-wideband (UWB) solution, but the Federal Communications Commission (FCC) does not allow fixed infrastructure outdoors for UWB, due to the potential to interfere with other radio devices. There are active RFID systems that operate at 433 MHz which can be used outdoors. You would need one transponder per person. Transponders cost about $50 apiece (or less if you buy them in large volumes). A transponder contains a battery and broadcasts a signal every minutes, every 30 seconds, every second—whatever rate you set it to. The more often the device beacons, the faster the battery dies. I think the challenge would be to install readers around the construction yard and power them. If that is feasible, then this type of system could do the job for you.
—Mark Roberti, Founder and Editor, RFID Journal
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