Hi guys, can anybody please advise on the issue below.
I am using a MT3329 gps in one of my project. The gps is connected to a serial port of my computer and I am using NMEA GPGGA interval to track the gps position change. If I move fast from a point A to a point B the gps shows position change quite accurately (say in MiniGPS app), but if I walk slowly between the same points the NMEA sentence does not show any position change at all. Is it expected behavior? Does anyone have any idea?
Thanks, Vadim.
Replies
Thank you - I spent several hours with this topic before finding this thread...
I was solving the same issue for GPS which used Mediatek MT3333 chip (Glonass+GPS) - position was freezed for slow speeds.
I realized that there is a new command for disabling the Navigation Speed threshold (working with newer chips e.g. MT3339):
$PMTK386,0*23<CR><LF>
The old command $PMTK397 is still supported by the chip, but it will not change the threshold - which is misleading.
PMTK command reference - originally for Adafruit MTK3339-based GPS:
https://www.adafruit.com/datasheets/PMTK_A11.pdf
Thank you for adding up this discussion. I had today the same problem as you and couldn't understand the reason before reading your thread. I would like to know if you tried the Navigation Speed threshold of 0 m/sec and how is it doing?
Thank you.
ACD
You have an error of +/- 9 feet in any direction. Unless your point A and point B are farther than 18 feet apart, it's entirely possible there is no change. That's true with any GPS.