Forums >Gears and Wears>Garmin 305 - crazy elevation readings around tall buildings???
I run in Boston along the Charles River and finish at my office across the street from the John Hancock tower. When I load my Garmin data, the elevation goes from around sea level and suddenly SKYROCKETS to like 250 feet in a fraction of a mile. You'd think I was Superman.
Has anybody else encountered this? It happens every time. It's very bizarre.
Whatever my lot, thou hast taught me to say, It is well, it is well with my soul.
Garmin elevation is only slightly better than you would get by pulling numbers from a random number generator. I haven't looked at the watches elevation data since about a week after I got it. It is just completely useless.
I've ran out and back courses and it's quite amusing to see the randomness of the elevation mappin. Yes, Garmin elevation is useless.
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For example, this morning I located satellites and started running. My 1-mile auto-lap feature started beeping every few seconds. I stopped and lap-reset a few times till it settled down, but I also saved uploaded the resulting 'workout' and course here:
http://www.runningahead.com/logs/8d3e7f3d441c43bda9540bb149d88cc5/workouts/4fc4c0f805f645d38e734116bfd20a3a/map
You can switch to the 'summary' tab to see the garmin reported intervals
By the way, I had to manually fudge the total time (Info - Duration), as RA would not let me save this as a run or anything else. It kept giving me the message "Do you really run this fast?" Cute. I don't run that fast, except maybe the part where I apparently went from 10000 feet to 2000 feet in one second.
The Limping Jogger
Readings are impacted by the fact that the GPS signal(s) bounce of the buildings and so you may receive the same transmission from two or more sources. This causes variations in timing hence impacting accuracy. The result is general crappyness in urban areas.
"Only a few more laps to go and then the action will begin, unless this is the action, which it is."
GPS works on triangulation, the more satellites received, the more accuracy. The watch receives fewer satellites around tall buildings. Fewer satellites = less accurate triangulation in both elevation and position, and takes longer to initially acquire a signal. In NYC typically on 5th Avenue my 405 usually won't acquire a sufficient signal until I get to the open (park). Multipath (bouncing off buildings) may add to the problem.
The elevation inaccuracy, even when getting many satellites, has been discussed extensively. It all boils down to satellite geometry.
There is clearly something new wrong with my 305's elevation data......it actually produced a reasonable elevation chart. The top is Garmin, the bottom RunningAhead. I was running on a small road through a pretty tall forest. I would not have called my view of the sky good, but this is one of the more accurate charts I have seen from my watch.
I've got a fever...
The top chart looks like it's from MotionBased. If so, is MBGravity (elevation correction) turned on? Just curious.
On your deathbed, you won't wish that you'd spent more time at the office. But you will wish that you'd spent more time running. Because if you had, you wouldn't be on your deathbed.
There has always been the issue of inaccurate elevation data, along with inaccurate lat/lon especially in the vicinity of buildings, under bridges, etc.
The new issue I have been seeing is, under a clear, unobstructed sky, having it put my location at 800 feet to as much as 10,000 feet higher than I actually am. I have only seen this level of altitude error in the past month or so.
rectumdamnnearkilledem
I run in Boston along the Charles River and finish at my office across the street from the John Hancock tower. When I load my Garmin data, the elevation goes from around sea level and suddenly SKYROCKETS to like 250 feet in a fraction of a mile. You'd think I was Superman. Has anybody else encountered this? It happens every time. It's very bizarre.
I get this on a section of rail trail that goes under a 4 lane business route where I live. It's pretty funny.
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