Distance estimation using signals of different frequencies

One or more processor readable media storing executable instructions that, when executed by one or more processors of a first device, cause the one or more processors to perform acts comprising:

• changing a signal frequency of a signal generator to a first frequency;
• synchronizing signals generated from the signal generator with a local clock of the first device at a first time;
• receiving a first signal from a second device;
• changing the signal frequency of the signal generator to a second frequency;
• synchronizing the signals generated from the signal generator with the local clock of the first device at a second time, a difference between the second time and the first time being within a predetermined range of a predetermined time difference;
• receiving a second signal from the second device;
• and
• obtaining a first estimated value for a distance between the first device and the second device based at least in part on a phase difference between the first signal and the second signal.

A system implemented by a first processor chipset, the system comprising:

• one or more processors;
• and
• memory storing executable instructions that, when executed by the one or more processors, cause the one or more processors to perform acts comprising:
• changing a signal frequency of a signal generator to a first frequency;
• synchronizing signals generated from the signal generator with a local clock of the processor chipset at a first time;
• receiving a first signal from a second processor chipset;
• changing the signal frequency of the signal generator to a second frequency;
• synchronizing the signals generated from the signal generator with the local clock of the first processor chipset at a second time, a difference between the second time and the first time being within a predetermined range of a predetermined time difference;
• receiving a second signal from the second processor chipset;
• and
• calculating a distance between the first processor chipset and the second processor chipset based at least in part on a phase difference between the first signal and the second signal.