GPS Area Calculation


Important note for using GPSMeter PDA with GPS SiRF based chipset.

What's the Static Navigation?

The static navigation mode has been introduced for road navigation, to avoid permanent changes of the coordinates, that would imply continous recalculation of itinerary and continous map movements.

See the note in the section 2-15 of "SiRF Binary Protocol Reference Manual"

Note – Static navigation is a position filter designed to be used with motor vehicles. When the vehicle’s velocity falls below a threshold, the position and heading are frozen, and velocity is set to zero. This condition will continue until the computed velocity rises above 1.2 times the threshold or until the computed position is at least a set distance from the frozen place. The threshold velocity and set distance may vary with software versions.

Some references say that velocity's threshold is about 5 Km/h, thus for any other use of the GPS other than car navigation (ie, for using GPSMeter PDA walking) you must turn off the static navigation mode.

This feature can be safely switched either ON or OFF with several tools. We present here the way to Switch OFF Static Navigation using SirfTech because have a great degree of control for the user.

Step by step switching Static Navigation with SirfTech.

First, the video of the process:

Video demo (AVI format)

Detailed explanation: Initially the GPS comes in the protocol NMEA because is the most used by the programs (including GPSMeter PDA). But the switching of Static Navigation only works in protocol SiRF, thus you must first change from NMEA protocol to SiRF, then change the Static Navigation status (to ON or OFF) and back again to NMEA protocol.

Step by step
1) Open SirfTech (Go to SirfTech Web, and copy the file built for ARM -unzipped- to your device)
2) Go to Com tab. Choose Comm Port and Bauderate and Open the port. Once open (NMEA counter grows), press Ok to close Com tab.
3) Go to NMEA menu and choose "Set Serial Port (Switch to SiRF)". Press Set and wait until SirfTime grows. Press Ok to close this window.
4) Go to SiRF menu and choose "Static Navigation". Uncheck the "Static Navigation" box and press Set. Wait for a second a press Ok to close this window.
5) Go to SiRF menu and choose "Switch to NMEA Protocol". Press Set and wait until NmeaTime grows. Press Ok to close this window.
6) Go to Com tab and verify that the NMEA counter messages changes. Close the port and exit, press OK and close the program using Exit


Static Navigation and EGNOS/WAAS corrections can also be configured from GPSMeter PDA.

gps area
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