|
Cellular forums Home > Archive > Garmin GPS > September 2005 > Problem with $PGRME?
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
Problem with $PGRME?
|
|
| Martin Bach 2005-09-14, 5:48 pm |
| I am interested in the error estimation provided by Garmin's $PGRME.
On the web I found several documents quoting the following example:
$PGRME,15.0,M,45.0,M,25.0,M*22
15.0,M Estimated horizontal position error in metres (HPE)
45.0,M Estimated vertical error (VPE) in metres
25.0,M Overall spherical equivalent position error
looks like we have
horizontal error < overall error < vertical error
in this this example. so far, so good.
Now let's have a look at a $PGRME from my Etrex Venture:
$PGRME,4.4,M,5.9,M,7.4,M*21
According to the documentation I have seen so far this would mean:
horizontal error < vertical error < overall error
Although I am not yet familiar with the mathematical background of this
error estimation (anyone got docs?), this seems odd to me. Shouldn't
the overall error range somewhere between the horizontal and the
vertical error?
Anyone got an idea what's going on here? I don't..
| |
| Martin Bach 2005-09-15, 5:48 am |
| I just found out that the example sentence I found on the web is not
valid NMEA, $PGRME,15.0,M,45.0,M,25.0,M*22 contains a checksumm error,
maybe it's invented.
Is it correct that the equation EPE^2 = HPE^2+VPE^2 is always true?
|
|
|
|
|