for static performance and found some interesting things:
1. I am using NMEA mode at 38400 Baud
2. The Module was first tested on the same position, without movements.
After roundabout 30 seconds, the Position output shows absolutely no jitter,
The Lat and long coordinates of the last point are inifinitely repeated with the identical values. I think, this was implemented to avoid erroneous tracks, when a vehicle is at rest.
3. Then i did some datalogging, while walking around. Same behavoiur: When at standstill, the output was "frozen" after 30 seconds. But the most important thing is, that after "restarting" to walk, the position was still locked for some 10 seconds! After about 40 meters, the next fix position was available.
4. Also, whilst walking (at a speed of about 4 km/h) the position got stuck sometimes. So there was no "smooth" position update.
I do not know, if this only happens in NMEA mode. If this is also the case in binary mode, this will make a position hold for a VTOL, like the Arducopter impossible, because it takes too long time to "wake up" after a position hold.
Any ideas?
Replies
When driving trough a tunnel, it produced dead-reckoning coordinates, that were all clamped to the last point with a valid fix. After the tunnel, the reaquisition went fast. Also, the startup problems, at longer rests (about one minute) are no longer there. Seems, that this is no GPS for pedestrians :-)
you are right, but actually i am using the module for two totally different projects. And NMEA is the best choice to move easily between various modules. Anyway, Binary is also feasible and i will try in the next days. Some questions about binary: I thought, when switching to DIYDrones mode, we will have fixed 38400Baud and an update rate of 10 Hz. right?
Or is there also an option to change the update rate even in binary mode?
I have added a Google earth screenshot with adirect comparision between the MTK and the EM406, both in 1Hz mode.
I stopped 2 times for about 1 minute. The effect is clearly visible for the MTK. I think, that that the Kalman filter inside the MTK is
is not so smooth for sake of speed. It seems, that the MTK has problems with looow speed.
To be continued...
MTK_EM406.jpg