The downloaded points will be available in the application as Users’ POIs. You will be able not only to easily choose and
navigate to the selected points, but along with the download you will also receive a lot of additional POI data, like phone
number, opening hours or range of rendered services.
4 GPS system
AutoMapa uses the GPS navigation system to accurately determine your position and display it on the digital map.
4.1 Introduction to GPS
Automatic navigation in AutoMapa utilizes the Global Positioning System, made
available for civilian use by the U.S. Department of Defense. A GPS receiver
calculates its position by measuring the distance between itself and several (out of 24
operating) visible satellites of the Navstar network.
The more satellites the receiver can detect, the more accurate the calculations will be.
Usually, as much as 4 to 6 satellites are visible (the maximum number is 12). The
minimal number of satellites required to determine the receiver's position is three.
Conditions for GPS reception
In ideal conditions, a typical GPS receiver used with AutoMapa can calculate its
position exact to a few metres. However, the GPS signal may be absorbed by building
walls, thick tree crowns, metal shieldings, or metalized and heated car windows.
Covering the receiver with a hand or a newspaper may also, to a lesser extent,
weaken the signal. The quality of GPS signal depends on the state of atmosphere,
both its upper (e.g. ionosphere) and the lower layer that influences the weather conditions. Sometimes, on cloudy and
humid days the GPS receiver may have problems with calculating its position. Another frequent problem related to
problems with GPS reading is incorrect cabling or close proximity to electronic devices that generate interference, and in
particular to devices used to monitor vehicle movement.
The accuracy of calculating the GPS position is greater, if the GPS receiver antenna is not covered, preferably in the open,
where the signal is not absorbed by buildings or thick foliage.
Extrapolate position
AutoMapa is adapted for city navigation and as such is equipped with solutions improving GPS reading by extrapolating
the vehicle's position based on the analysis of its direction and speed. However, the map can show a position outside the
route, e.g. when taking a fast turn. The "Extrapolate position" function can be turned on/off by selecting the setting you
want in "GPS - Settings" in the main menu. In this option you can also manually specify the time when AutoMapa
extrapolates/overtakes the GPS position obtained from the GPS receiver. This time depends on CPU speed, display rate
and palmtop memory.
4.2 Fixing GPS position
If, after turning on the GPS receiver, the "Searching for GPS signal" is played, and after a dozen or so minutes the correct
position is not found, that means the following:
• receiver has been detected by AutoMapa, but it relays information in non-supported protocol (other than NMEA
0183), or
• automatic COM port detection failed, or
• GPS signal is interfered with resulting in a failure of the GPS receiver to calculate the current position (e.g. user
remains indoors).
It should be noted that the so-called cold start (i.e. start after long non-use) or the first start of the GPS receiver may, in
case of certain models, take as much as dozen minutes or more. Before starting the troubleshooting, you should wait a
while longer.
After calculating the GPS position, AutoMapa automatically switches to the GPS tracking mode where the current position
is always displayed on the map.
The current position is indicated on the map as a pulsating circle with a direction arrow inside.
4.3 GPS receiver connection
GPS receiver - requirements
AutoMapa is supported by GPS receivers with COM interface (i.e. serial port for connecting to PCs), which relay their
position in the GPS NMEA 0183 protocol.
