Is it possible to take four readings per second of a tag when considering the movements of a particular item?
Active RFID solutions typically allow you to set the interval at which a tag will emit its signal. If you want to conserve battery life, you might set the tag to beacon every 30 seconds, for example. If battery life is not important but precise location is, you could set the tag to beacon every second. The settings you can choose differ from one vendor to the next, so you would need to ask your tag provider what the fastest beacon rate possible is for your particular tags.
—Mark Roberti, Founder and Editor, RFID Journal