Patent ID: 7512113
Filing Date: 2009-03-31
Classification: H04J

Abstract:
1. A method of determining a minimum time of flight of a radio frequency (RF) transmission between a first communication device and a second communication device, the method comprising: transmitting from the first communication device via a first RF channel a range request message to the second communication device, wherein the range request message includes a first periodically repeating synchronization sequence; receiving at the first communication device via a second RF channel a range response message from the second communication device, wherein the range response message includes a second periodically repeating synchronization sequence and a minimum path turn around time, wherein a change in the second RF channel is induced after receipt of each synchronization sequence; determining a minimum path round trip time from multiple time of arrival determinations, wherein the minimum path turn around time is determined by: calculating the minimum time of flight from the minimum path round trip time and the minimum path turn around time.