Patent ID: 11917569
Assignee: LANDIS+GYR TECHNOLOGY, INC.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 7:
8. A system, comprising:
a reference device configured for transmitting a reference timing signal to a plurality of endpoint devices in a mesh network; and
the plurality of endpoint devices, each endpoint device of the plurality of endpoint devices configured for:
while operating in an initial communication mode,
receiving the reference timing signal over the mesh network from the reference device;
obtaining a current value of a frequency of a crystal oscillator of the endpoint device, wherein the reference device is synchronized to a clock with a frequency of higher accuracy and stability than the frequency of the crystal oscillator;
determining a frequency difference between a reference frequency of the reference timing signal and the current value of the frequency of the crystal oscillator;
generating a control signal based on the frequency difference;
adjusting, according to the control signal, the crystal oscillator to adjust the frequency of the crystal oscillator; and
determining that an error of the frequency of the crystal oscillator satisfies a pre-determined condition;

in response to determining that an error of the frequency of the crystal oscillator satisfies a pre-determined condition, switching to a narrowband or ultra-narrowband communication mode, wherein a data rate of the narrowband or ultra-narrowband communication mode is lower than a data rate of the initial communication mode; and
communicating with the reference device or another endpoint device in the mesh network using an oscillating signal generated by the crystal oscillator while operating in the narrowband or ultra-narrowband communication mode.