GNS006 - GPS Module
Tae-min Hwang
GPS(Global Positioning System)
- GPS determine the position vector using micro wave from satellites
- It uses trilateration to calculate correct position
Satellites signal
- Satellites broadcast the navigation message which includes times, almanac,
ephemeris data, and the coefficient for calibration continuously in 50 bps speed.
Almanac : The orbit information of all satellites that includes the sight calibration value, Latency parameters, etc.
It is refreshed once in several months.
Ephemeris : The expected orbit calibration information of satellites
It is refreshed each 2 hours and valid for 4 hours.
Important concepts
Hot start, Warm start, Cold start
• They are related with the Time to first Fix(TTFF)
• Hot start
- When using GPS receiver 2 ~ 4 hours before
- Ephemeris and Almanac data are valid
- Use all stored data in GPS module
• Warm start
- When using GPS receiver about 1 day before
- Almanac data is valid, But Ephemeris data is not used
• Cold start
- When using GPS receiver about 1 day before
- Almanac data is valid, But Ephemeris data is not used
Block Diagram
Characteristic
Characteristic
Acquisition time
Average acquisition in cold start 36.1 sec
Power Consumption
Power Consumption
Standby Mode
Power Consumption
Active mode (tracking)
Power Consumption
Active mode (acquisition)
Reacquisition Time
3.31 s
Average 2 ~ 3 sec
Additional Function Description
AGPS with EPO data
– It allows to shorten TTFF (TimeToFirstFix) by injecting ephemeris data from an external
source into the module’s memory
– There are 2 file (for 7 days, for 14 days)
AlwaysLocate mode (not valid)
AlwaysLocate mode (valid)
Compare with other modules
Product
GNS601
GMS-G6
FGPMMOPA6B
EM506
Hot start (sec)
1
1
1
1
Warm start (sec)
34
33
34
35
Cold start (sec)
35
35
35
35
Acquisition
25 mA
29 mA
48 mA
50 mA
Tracking
20 mA
20 mA
37 mA
34 mA
Acquisition Time
Power Consumption
NMEA Protocol
NMEA Command Interface
MTK NMEA Packet Format
RMC Data
GSA Data
GGA Data
Implementation
Write API for ESTK board
Further work
• Implement additional function
• Check about AlwaysLocate mode and AGPS data mode