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11.2 GNSS Principle Of Operation
Two GNSS modes are implemented:
•
the GNSS autonomous mode does not require any assistance location or almanac data, and aims at detecting strong
satellite signals. Therefore is suitable for outdoor conditions with good sky visibility.
•
the GNSS assisted mode allows the most efficient GNSS geolocation. Assistance information allows building a list of
satellites in view at the current time and at the current location, in order to reduce the GNSS satellites search space,
and thererfore optimize the time and energy spent for the geolocation. The assistance information is tailored to a
LPWAN network, limiting the data to be sent, especially the downlink size and frequency. It consists in:
the LR1110 approximate position (within +/-150km range)
the current time (within +/- 1 s)
up-to-date reduced size Almanac information (less than 3 months old)
The LR1110 supports both GPS L1 and BeiDou B1 signals. The LR1110 is able to perform either a single GNSS in any (or both)
GPS and BeiDou constellations, or a dual GNSS BeiDou in any (or both) GPS and BeiDou constellations.
During the GNSS, the BUSY signal is set High, indicating that LR1110 is not ready to accept SPI transactions. BUSY returns
to Low when the procedure is complete. If the GNSSDone interrupt has been enabled, the IRQ pin goes high at the end of
the GNSS process.
A TCXO is mandatory for any GNSS operation.
LR1110
User Manual
Rev.1.0
UM.LR1110.W.APP
March 2020
Figure 11-1: GNSS System Overview
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