RFID readers transmit data to query tags at one or more data rates. Before transmitting data, the RFID readers also transmit special preambles that inform of the data rate that will be used for transmitting the data. The preambles have a call aspect and a rate aspect. The rate aspect has a feature substantially...http://www.google.com/patents/US20050237162?utm_source=gb-gplus-sharePatent US20050237162 - RFID readers transmitting preambles denoting data rate and methods
