Method and system for radiolocation asset tracking via a mesh network
A method of determining a reference clock in a mesh network includes receiving multiple signals, correlating the multiple signals with a local signal generated by the first node to determine a coarse set of time differences, refining the coarse set of time differences using a phase of a carrier signal of the multiple signals to produce a refined set of time differences, and using the refined set of time differences to define a reference clock.
1. A method of determining a reference clock for use in a mesh network, comprising:
generating, at the first node, a local signal;
receiving, at a first node in the mesh network, multiple signals from a second node in the mesh network;
demodulating the local signal to locate a local signal peak;
demodulating the multiple signals to locate multiple signal peaks;
correlating, at the first node, the local signal peak and the multiple signal peaks to determine an offset for the second node;
determining a coarse set of time differences using the offset for the second node;
refining the coarse set of time differences using a phase of a carrier signal of the multiple signals to produce a refined set of time differences; and
using the refined set of time differences to define the reference clock for use in the mesh network.
2. The method of claim 1 , wherein receiving the multiple signals comprises receiving pseudorandom ranging codes from the second node.
3. The method of claim 1 , wherein refining the coarse set of time differences comprises:
determining a frequency and phase of the carrier signal;
using the frequency and phase of the carrier signal to determine a fractional offset between carrier signal and the coarse set of time differences; and
using the fractional offset to adjust the coarse set of differences to a higher level of precision than the coarse set of differences.
4. The method of claim 1 , further comprising receiving, at the first node, multiple signals from at least a third node in the mesh network and performing the correlating, the refining and the using for at least the third node.
5. The method of claim 4 , wherein the correlating is performed between each node of the mesh network.
6. A method of determining a reference clock for use in a mesh network:
receiving, at a first node in the mesh network, multiple signals from a second node in the mesh network;
correlating, at the first node, the multiple signals with a local signal generated by the first node to determine a coarse set of time differences;
determining a frequency and phase of the carrier signal;
using the frequency and phase of the carrier signal to determine a fractional offset between carrier signal and the coarse set of time differences; and
using the fractional offset to adjust the coarse set of differences to a higher level of precision than the coarse set of differences to produce a refined set of time differences; and
using the refined set of time differences to define the reference clock for use in the mesh network.
7. A method of determining a reference clock for use in a mesh network:
receiving, at a first node in the mesh network, multiple signals from a second node in the mesh network;
receiving, at the first node in the mesh network, multiple signals from a third node in the mesh network;
correlating, at the first node, the multiple signals from the second node and the multiple signals from the third node with a local signal generated by the first node to determine a coarse set of time differences;
refining the coarse set of time differences using a phase of a carrier signal of the multiple signals from the second node and a phase of a carrier signal of the multiple signals from the third node to produce a refined set of time differences; and
using the refined set of time differences to define the reference clock for use in the mesh network.