Mobile device utilizing time of flight for personal security and localization

A method for determining the location of a frequency receiver device with respect to at least two frequency originator devices, each of a known location, said method comprising:

• (a) synchronizing a clock of said frequency receiver device with a clock of one of said at least two frequency originator devices;
• (b) receiving by said frequency receiver device, a message containing a broadcast time at which said message is broadcasted from said one of said at least two frequency originator devices;
• (c) calculating a time of flight of said message by calculating the difference between a receive time at which said message is received by said frequency receiver device and said broadcast time;
• (d) repeating steps (a)-(c) for another one of said at least two frequency originator devices to result in a first time of flight and a second time of flight;
• (e) calculating a ratio of said first time of flight and said second time of flight;
• (f) resolving possible locations of said frequency receiver device by looking up a table containing possible locations of said frequency receiver device with respect to the locations of said at least two frequency originator devices;
• and (g) applying at least one limit to said possible locations to select one of said possible locations with high certainty.

A method for determining the location of a frequency originator device in a system having a frequency receiver device and the frequency originator device, said method comprising:

• (a) broadcasting a first message from a master frequency originator device, wherein said first message comprises a first identification code indicating the source of its broadcaster;
• (b) upon receiving said first message in the frequency receiver device, looking up a list of frequency originator devices associated with said first identification code from a first table correlating master frequency originator devices and their associated frequency originator devices based on said first identification code and caching a first value associated with a counter of each frequency originator device of said list of frequency originator devices in the frequency receiver device, wherein each frequency originator device of said list comprises a second identification code;
• (c) upon receiving said first message in the frequency originator device, broadcasting a second message from the frequency originator device, said second message comprises an identification code selected from said second identification codes of said list of frequency originator devices;
• (d) upon receiving said second message in the frequency receiver device, caching a second value of the counter associated with the frequency originator device as identified by said second identification code of said second message;
• and
• (e) determining the location of the frequency originator device by looking up a location from a second table correlating locations of a frequency originator device and counter values associated with the frequency originator device, based on the difference between said second value and said first value.