GPS about 30m off

Edwin 8 months ago

I have noticed this twice now. After using my GPSmap 67i for a few hours the gps is at once way off.

We went for a little walk this evening to find a cache. The gps worked fine until the last waypoint. We were on the right spot and according to the gps we were 30m away from that waypoint.

In the hurry of that moment I didn't notice the fault right away, but being home in my backyard I see the gps is still way off.

Multi-GNSS is selected and Multi-Band is on. According to the Satellite page there could be a variation of 1.8m. On the map I can see the gps is at least 30m off.

Switching the device off and on solves it directly. I had the same experience yesterday (not caching or walking at that time, just playing with this new toy at home), so it is not just a one time glitch.

I wonder if someone else has this experience as well and I hope someone can tell me I can solve this behavior by myself.

Regards,

Edwin.

Top Replies

Chris 2 months ago in reply to scubajorgen +1

As I already wrote above, I have the same problem. The Garmin support told me, that this is a normal behaviour. As I cannot belive that, I talked to my retailer to replace the GPSmap with a new one and…
scubajorgen 1 month ago in reply to skyeye +1

skyeye said:
I do not understand what is this all about. I do not know anything else then this for years, not only Garmin products, but other simple gps devices. When I put such device on top of a high…

All Replies

0 scubajorgen 29 days ago in reply to JungleJim

You are to quick with your response JungleJim, I hadn't finished

Yes, I took the data from the .FIT files. I wrote software to derive the data from the .FIT files with cm accuracy.
I converted WGS84 coordinates to the Dutch Map Datum (RDNew), which expresses the coordinate as Northing and Easting, in meter. I believe this is more accurate than calculating distances using Haversine, since the Dutch Map Datum is especially for Dutch territory. It also made calculation easier (pythagoras...). All in Matlab
RINEX is on my bucketlist. I need some conversion software that derives coordinates from the raw satellite distances. RTKLib requires an academic degree it seems...

0 JungleJim 28 days ago in reply to scubajorgen

Great, you seem to know your stuff

RINEX data analysis would indeed be interesting. Early firmware versions of the GPSMAP 67 produced RINEX data that was simply incorrect (missing bands, duplicated data to name a few). Garmin fixed it eventually, so it would be interesting to see if the data is actually correct and useful.

Hopefully Garmin engineers can do something with the info in your blog post.

PS. Groetjes vanuit Nederland