US 12,192,951 B2
Synchronization of receiver and transmitter local oscillators for ranging applications
Rangakrishnan Srinivasan, Austin, TX (US); and John Khoury, Austin, TX (US)
Assigned to Silicon Laboratories Inc., Austin, TX (US)
Filed by Silicon Laboratories Inc., Austin, TX (US)
Filed on Mar. 27, 2024, as Appl. No. 18/618,458.
Application 18/618,458 is a division of application No. 17/550,417, filed on Dec. 14, 2021, granted, now 11,979,846.
Prior Publication US 2024/0244572 A1, Jul. 18, 2024
Int. Cl. H04L 7/033 (2006.01); G06F 1/04 (2006.01); H04W 64/00 (2009.01)
CPC H04W 64/00 (2013.01) [G06F 1/04 (2013.01); H04L 7/033 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of performing a distance measurement between a first network device and a second network device, comprising:
transmitting a first packet from the first network device to the second network device, using a first frequency;
replying to the first packet by transmitting a second packet from the second network device to the first network device using the first frequency;
transmitting a third packet from the first network device to the second network device using a second frequency, different from the first frequency;
replying to the third packet by transmitting a fourth packet from the second network device to the first network device using the second frequency; and
calculating a distance based on a phase received by the first network device and the second network device for each packet, the first frequency and the second frequency,
wherein the first network device and the second network device each comprise a clock generation circuit having a phase locked loop and one divider disposed outside the phase locked loop to generate a receive clock and a transmit clock, such that a phase difference between the transmit clock and the receive clock of each network device is constant.