User's Manual

UMTS/HSPA Module Series
UC20 Hardware Design
UC20_Hardware_Design Confidential / Released 55 / 84
4 GNSS Receiver
4.1. General Description
UC20 includes a fully integrated global navigation satellite system solution that supports the latest
generation gpsOne Gen8 of Qualcomm (GPS and GLONASS). Compared with GPS only, dual systems
increase usable constellation, reduce coverage gaps and TTFF, and increase positioning accuracy,
especially in rough urban environments.
UC20 works in standalone mode, allows device to demodulate GNSS assistance data, calculate position
without any assistance from the network, suitable for various application needing lowest-cost, accurate
position determination. UC20 supports Qualcomm gpsOneXTRA technology (one kind of A-GNSS), which
will download XTRA file from the internet server to enhance the TTFF. XTRA file contains predicted GPS
and GLONASS satellites coordinates and clock biases valid for up to 7days. It is the best if XTRA file is
downloaded once every 1-2 days. And UC20 also supports SBAS (including WAAS, EGNOS and MSAS),
which will improve fix accuracy.
UC20 provides power-saving solution named DPO (Dynamic Power Optimization), which attempts to turn
off GNSS RF parts, reduces current consumption by 50% at most without impact on TTFF and extends
battery life, maximizes talk and standby time as well.
UC20 supports standard NMEA-0183 protocol, and outputs NMEA sentences with 1Hz via USB interface
by default.
By default, UC20 GNSS engine is switched off, it has to be switched on with AT command. For more
details about GNSS engine technology and configurations, refer to document [7].