User's Manual

GSM/GPRS/GNSS Module Series
MC20 Hardware Design
MC20_Hardware_Design Confidential / Released 64 / 95
3.12. EASY Autonomous AGPS Technology
Supplying aiding information like ephemeris, almanac, rough last position, time and satellite status, can
help improve the acquisition sensitivity and the TTFF for a module. This is called as EASY technology and
MC20’s GNSS part supports it.
EASY technology works as embedded software which can accelerate TTFF by predicting satellite
navigation messages from received ephemeris. The GNSS part will calculate and predict orbit information
automatically up to 3 days after first receiving the broadcast ephemeris, and save the predicted
information into the internal memory. GNSS part of MC20 will use the information for positioning if no
enough information from satellites, so the function is helpful for positioning and TTFF improvement.
The EASY function can reduce TTFF to 5s in warm start. In this case, GNSS’s backup domain should be
valid. In order to gain enough broadcast ephemeris information from GNSS satellites, the GNSS part
should receive the information for at least 5 minutes in good signal conditions after it fixes the position.
EASY function is enabled by default. Command “$PMTK869,1,0*34” can be used to disable EASY
function. For more details, please refer to document [2].
3.13. EPO Offline AGPS Technology
MC20 module features a function called EPO (Extended Prediction Orbit) which is a world leading
technology. When MC20 module is powered on, EPO function can be enabled via AT command
AT+QGNSSEPO=1. When the GSM part detected that the EPO data has expired, the EPO data will be
automatically downloaded to the GSM part’s FS from MTK server via GSM/GPRS network; and the GNSS
part will get the EPO data via build-in GNSS command from GSM's FS when it detected that the local
EPO data has expired. When there is no local EPO data or when the data has expired, MC20 module will
download the data (4KB) for 6 hours’ orbit predictions in order to achieve cold start in the shortest time,
and then continue to download the EPO data (48KB) for 3 days. The technology allows the module to
realize fast positioning. Command AT+QGNSSEPO=0 can turn off the EPO function.
In all-in-one solution, make sure the GNSS part is powered on before sending the PMTK command.
Make sure the EPO function is enabled if you need to download the EPO data.
NOTE
NOTE