Doppler ranging system
AssigneeSemtech Corporation
InventorsOlivier Bernard André SELLER, Christophe Jean Jacques DEVAUCELLE
Life of this patent
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Abstract
An extension of the LoRa modulation with an improved ranging mode. A master and a slave device exchange a request and a reply that contain sequences of chirps that are carefully aligned in time, frequency, and preferably also phase, such that the master device can ascertain the propagation delay to the slave by demodulating the reply. Request and reply include chirps having different slopes, preferably slopes of equal absolute value and opposite sign. The slope diversity permits an unbiased estimation of the Doppler shift.
Claims17
A system comprising a first radio device, acting as master (A) and a second radio device, acting as slave (B), each of the first and second radio devices having a time reference and being arranged for transmitting and receiving radio signals that include a plurality of chirps, said first and second radio devices having a ranging mode in which the first radio device (A) transmits to the second radio device (B) a ranging request containing ranging chirps (416, 417), and the second radio device (B) responds to the ranging request transmitting to the first radio device (A) a ranging reply containing reply chirps (419, 418), the second radio device (B) is configured to align the reply chirps in time and frequency with the ranging chirps, the system being configured to determine a range between the first radio device and the second radio device, based on time shifts between the ranging chirps and the reply chirps, characterized in that the ranging chirps do not have all the same slope.
Dependencies are inferred from the claim text.