One way ranging synchronization and measurement
AssigneeSilicon Laboratories Inc.
InventorsTerry Lee Dickey, Yan Zhou, Michael Wu
Life of this patent
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Abstract
A system and method for one-way ranging is disclosed. The system comprises a transmitter, also referred to as tag, transmitting a packet having a first frequency. The receiver, also referred to as the locator, receives the first frequency and measures the phase at a specific point in time. At a predetermined time, the transmitter switches to a second frequency. This is performed while maintaining phase continuity. The receiver also switches to the second frequency at nearly the same time. The receiver then measures the phase of the second frequency at a second point in time. Based on these two phase measurements, the distance between the transmitter and the receiver may be calculated.
Claims18
A method of determining a distance between two network devices, comprising:
- transmitting, from a first network device, a range detection packet, wherein the range detection packet comprises a first constant tone wherein a first frequency is transmitted and a second constant tone wherein a second frequency is transmitted and wherein there is phase continuity during a transition from the first constant tone to the second constant tone;
- receiving, at a second network device, the range detection packet;
- sampling, at the second network device, the range detection packet using a sample clock, wherein the sample clock has phase continuity during the transition from the first constant tone to the second constant tone, wherein the second network device samples a phase of the first constant tone to create a first sample having a first phase and samples a phase of the second constant tone to create a second sample having a second phase;
- determining a frequency difference between a clock used by the first network device and the second network device;
- using the frequency difference, the first phase and the second phase to determine a distance from the second network device to the first network device.
A system for measuring a distance between two network devices, comprising:
- a first network device to transmit a range detection packet, wherein the range detection packet comprises a first constant tone wherein a first frequency is transmitted and a second constant tone wherein a second frequency is transmitted and wherein there is phase continuity during a transition from the first constant tone to the second constant tone;
- and
- a second network device, comprising:
- a network interface,
- a processing unit, and
- a storage device containing instructions, which when executed by the processing unit, enable the second network device to:
- receive the range detection packet;
- sample the range detection packet using a sample clock, wherein the sample clock has phase continuity during the transition from the first constant tone to the second constant tone, wherein the second network device samples the first constant tone to create a first sample having a first phase and samples the second constant tone to create a second sample having a second phase;
- determine a frequency difference between a clock used by the first network device and the second network device;
- and
- determine a distance from the second network device to the first network device using the frequency difference, the first phase and the second phase.
Dependencies are inferred from the claim text.