Datasheet

NEO-M8U - Data Sheet
UBX-15015679 - R06 Functional description Page 9 of 27
Product Information
1.6.3 AssistNow
TM
Autonomous
AssistNow Autonomous provides aiding information without the need for a host or external network
connection. Based on previous broadcast satellite ephemeris data downloaded to and stored by the
GNSS receiver, AssistNow Autonomous automatically generates accurate satellite orbital data
(“AssistNow Autonomous data”) that is usable for future GNSS position fixes. The concept capitalizes
on the periodic nature of GNSS satellites: their position in the sky is basically repeated every 24 hours.
By capturing strategic ephemeris data at specific times over several days, the receiver can predict
accurate satellite ephemeris for up to six days after initial reception.
u-blox’s AssistNow Autonomous benefits are:
• Faster fix in situations where GNSS satellite signals are weak
• No connectivity required
• Compatible with AssistNow Online and Offline (can work stand-alone, or in tandem with these
services)
• No integration effort; calculations are done in the background, transparent to the user.
☞ For more details see the u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification
Error! Reference source not found. and the MGA Services User Guide Error! Reference source not
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1.7 Augmentation Systems
1.7.1 Satellite-Based Augmentation System (SBAS)
The NEO-M8U positioning module supports SBAS. These systems supplement GPS data with
additional GPS augmentation data within defined service areas. The systems broadcast
augmentation data via satellite and this information can be used by GNSS receivers to improve the
resulting precision. In some cases SBAS satellites can be used as additional satellites for ranging
(navigation), further enhancing precision and availability.
1.7.2 QZSS
The Quasi-Zenith Satellite System (QZSS) is a regional navigation satellite system that transmits
additional GPS L1 C/A signals for the Pacific region covering Japan and Australia. NEO-M8N
positioning module is able to receive and track these signals concurrently with GPS signals, resulting
in better availability especially under challenging signal conditions, e.g. in urban canyons.
1.7.3 QZSS L1S SLAS
QZSS SLAS (Sub-meter Level Augmentation Service) is an augmentation technology, which provides
correction data for pseudoranges of GPS and QZSS satellites. With the QZSS SLAS enabled, u-blox
receivers autonomously select the most suitable Ground monitoring stations (GMS) based on the
user’s location. The correction stream of this GMS will then be applied to the measurements in order
to improve the position accuracy.
1.7.4 IMES
The Japanese Indoor MEssaging System (IMES) system is used for indoor position reporting using
low-power transmitters which broadcast a GPS–like signal. NEO-M8N module can be configured to
receive and demodulate the signal to provide an in-door location estimate.
☞ This service is authorized and available only in Japan.
☞ IMES reception is disabled by default.