Hello, could some of the tech guys explain what is the new hdop feature in the latest MediaTek Firmware?
If I understand it is something to do with accuracy of the GPS signal but the value is much higher than what literature says.
I see in the comments that it is in cm. so basically if I have a hdop of 200 I am quite sure my accuracy is in between 2 meters, is that cosrrect?
Second question regard position. If I look in Google Maps/ Earth there is quite a difference in positioning:10-20 meters. Is that also correct? how could I check if I have everything set-up correctly?
THanks,
Emile
Replies
if I have a hdop of 200 I am quite sure my accuracy is in between 2 meters, is that cosrrect?
No.
It can only be used as a relative measure. It really should not be given a unit of distance. It is more a figure of "goodness" of the satellite geometry. (The inverse of the size of the volume that the satellites used in the calculation form -- if all the satellites are close together, giving a small volume, you have a high DOP. If you have a satellite low (but not too low) on the horizon N, E, S, W, and right overhead you have a large volume and a low DOP.) It does not take into account multipath errors, atmospheric errors, etc. Note that satellites really low on the horizon help DOP but are more subject to atmospheric effects.
The DOP magnifies the other errors. So a small DOP means that other errors have less effect. High DOP means that the other errors have a large effect.
1-2 great; 2-4 good; 4-6 fair; 6-8 kinda bad; 8+ don't bother. Usually 5 is considered the worst usable unless you really only need a rough estimate of position.
DOP flavors
H -- horizontal
V -- vertical
P -- position (H&V)
T -- time
G -- "geometric" H&V&time