Garmin 310 acting funny
Over the last month or so, my 310 has been spitting out some ludicrously stupid numbers, in both directions -- I have never run faster than 3 minutes a mile (nor has anyone else for that matter), and don't run slower than 10 minutes a mile on flats, even in Z1. I don't start running until it locks on satellites and brings up the ready screen, so I don't think that's the issue.
When I look at the map in training peaks, it's wrong. Either it thinks I am .25 miles away from where I actually was when I started, or it picks a path through the woods and houses next to the road that is .5-.25 miles shorter than the route along the road that I am actually running.
Does this happen to anyone else, and what, if anything can I do about it?
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I usually wait until at least a few minutes after I get a lock. And then to ensure it is correct, I wait until the pace settles down before I hit Start. I haven't seen the location errors...sorry.
Joe
GPS devices can be off by quite a bit when first started. Most times when It first gets a lock it will have me at 6:00/mi pace even though I am standing still. As it locks onto more satellites it will drop down.
If you pass under trees or such it can lose signal. If you go around a corner at this point it may miss some data and simply draw a straight line from where it lost the signal to where it picked it up again.
Another thing might be that the maps you are looking at are off a little. I have seen areas where it places me in a field every time even though I am on the road.
I also remember seeing something about Training Peaks having difficulty interpreting the 310xt data. What does the data say in Garmin Connect?
Office: The garmin has a lot of trouble getting a signal outside my office. I end up standing in a small clearing half a block away and wait until it locks on (can be up to five minutes). Once it has a finished acquiriing satellites, it flips to the ready screen. I wait until the current pace number zeros (usually has a momentary flicker), and then I start running. Last night, Mr. Garmin claimed I was running 8:30 a mile or slower on a slight downhill grade when I would have sworn I was running between 7:10 and 7:30. It's possible my RPE was off by that much, but I frankly doubt it. On the same loop a few weeks ago, it claimed I was running 11 minute miles when my RPE was 7:45-8:00. I noticed that when I stopped at lights, it was taking Mr. Garmin about 10 seconds to realize that I wasn't moving, and another 5-10 seconds to realize I had started again when the light turned green. The issue isn't really what training peaks says, it's what the Garmin is telling me. This problem doesn't seem limited to the first section, but continues throughout the run. I know that RPE can be off, but when HR and RPE are saying I am running a Zone 3-4 pace, while Mr. Garmin says I am running slower than Zone 1 (on a fairly flat portion), something is wrong. My bet is that Mr. Garmin is at fault.
Home : I should leave the Garmin in the open door while I am riding the trainer so it can acquire a signal, but I generally don't. I turn it on when I step outside and then walk slowly up the hill I live on to the crest (about 200 meters). Once I get to the top, it has usually locked on. Again, sometimes it has goofy pace numbers for a few seconds after locking its signal, but they goes away quickly. When I start running, however, it produces a goofy current pace number and an equally goofy average pace for the first mile or so about half the time. Sometimes, it claims I ran the first mile in 5:00 and the first 1/2 mile in 80 seconds, sometimes it claims I ran the first mile in 10 minutes and ran the first half mile in 6 minutes (my actual pace, based on RPE doesn't really change for that first mile, ever). When I look at the map, from trainingpeaks, the goofy fast miles have a "starting point" in the air (literally -- I live on a canyon road) a fair distance from where I actually started which it claims I covered in like 5 seconds, while the goofy slow miles show a dead straight line between where my run started and a similar point (the actual road curves around). In either case, on the return trip, the map shows me running along the road, just like I actually was.
The optimum constellation is to have 4 or more satellites 20 degrees above the horizon, equally spaced around your location 80 to 100 degrees apart. Buildings, canyon walls, trees, and other solid objects that obstruct the sky – especially along the horizon up to about 45 degrees above the horizontal, dramatically reduce the accuracy of your estimated position. Reflective surfaces make it worse by creating what is called multipath – multiple versions of the same signal traveling different distances before reaching your Garmin. Water, glass, wet leaves on trees, etc are examples of things that mess up your location. The entire system is very, very fuzzy and we haven’t talked about the disturbances in the atmosphere or ionosphere.
The way I explain the “fussy” locations to our foresters is: Every couple of seconds your location is calculated from the signals received from the GPS satellites. This location (you) is somewhere inside a circle with a radius of between 18’ and 50’. You are NEVER in the center of the circle. The circle grows and shrinks over time, sometimes very fast and is unpredictable. To make it even more unreliable the circle you are in wobbles on the ground. This is why when you are standing still and your Garmin says your pace is 7:30 or whatever – its because you are ‘jumping’ around the circle.
Because of all this fuzziness, instantaneous pace readings are ALWAYS wrong. Setting your Garmin to display Lap Pace will give decent results if you wait till you are at least 0.25 miles past the last recorded lap. I set my Garmin to vibrate every half mile and don’t look at the pace until it buzzes mid-mile or just before the next lap.
Your Garmin will also always read long on races. This goes back to fuzzy points. It doesn’t always get your location in the center of a road even if you follow the yellow line. One calculated location my be ahead of you off to the right, the next may be behind you to the left. Remember, any point location within the circle is acceptable, and sometimes the calculated position point falls outside the circle – actually as many as 10% of the points may be outside of the circle of probability, making your speed and distance that much worse.
Hope this helps
Run Strong
Do you swim with it or just leave it on the bike ready to go?
I swim with it.
My 310XT that I purchase over a year ago was one of the original version that had the screen that was prone to crack if dropped and the strap that could break. I swam with it for probably 8 races and a few open water swims. It worked perfect until last weekend.
During the oceanside swim, I got kicked in the watch/arm REALLY hard, and the garmin went crazy. I contacted garmin and am getting a replacement under warrenty as it is a none issue with the the first few batches of 310XTs. They said the new screen that is recessed and stronger does not have the issue and they have been making the new model for well over a year now. The screen is noticable recessed on the new one I received and therefore I have no fear about swimming with it again and will continue to use it on my wrist during the swim.
FWIW, it is more accurate if you put it under your swim cap, but I could care less on the distance of the swim. I just leave it on so I can see time and I don't have to mess with putting it on or turing it on during the race.