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Old 05-23-2014, 05:10 PM   #1
armourbl OP
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GPSmap 62S not recording speed correctly

I've had a GPSmap 62S for some time now. I mainly have used it on my mtn bike. Not long ago I noticed it stopped recording my average, max, etc., speeds correctly. I've tried everything I can think of to remedy this issue. It still records the tracks accurately, I question the reliability of other data.

Tried the factory reset. Tried updating software. Tried re-calibrating the compass. Not sure what else to do.

Any ideas?

ben
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Old 05-23-2014, 10:50 PM   #2
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What was your test method to prove it was wrong?

I would compare it to data from your car on cruse control.


They are simple math calculations that just depend on position and time data so if the recorded tracks look accurate all that leaves is time. Take a look at the time stamp on each track point and the MPH between points. Seams like they have to be off for the averages to be off.
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Old 05-24-2014, 03:59 AM   #3
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Time * Speed = Distance

That's the basic calculation we all (hopefully) learned in school. So if you change it around a little, Speed = Distance / Time. That's all a GPS does to get speed. If distance or time are not correct, speed will be way off. IT's why a GPS will sometimes tell you that your speed was hundreds or thousands of MPH.

And if you have the GPS turned on but not moving, it will mess with the average speed.

If you reset your data every regularly, it will be close, but it's not perfect.
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Old 05-24-2014, 05:01 PM   #4
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Well, when I first got the unit, it did a very good job of calculating my average. I know it is off because it tells me my max speed is something like 54mph when I'm riding a mtn bike on single track, mostly uphill -- and Lance Armstrong I am not...

Even my phone using Strava or something similar gives me more accurate average than my GPS. That don't seem right.

ben
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Old 05-24-2014, 05:34 PM   #5
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All the new generation units 62/78/Montana have a big flaw recording track points when not moving or moving very slow. They don't understand "stopped" and keep recording track pints like you are jumping around like crazy. Big complaint with guys trying to record accurate tracks for future use.

Try going to Track Set Up can change from "Automatic" to distance and set distance at something greater than 300 ft.
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Old 05-24-2014, 06:06 PM   #6
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Quote:
Originally Posted by Countdown View Post
All the new generation units 62/78/Montana have a big flaw recording track points when not moving or moving very slow. They don't understand "stopped" and keep recording track pints like you are jumping around like crazy. Big complaint with guys trying to record accurate tracks for future use.

Try going to Track Set Up can change from "Automatic" to distance and set distance at something greater than 300 ft.
Thanks. I'll give that a try. I mainly use my GPS for my mtn bike. So for now I'm going to try 0.01 miles (distance option is in miles only), which equates to about 50 feet. I'll up it to 0.02 if that doesn't improve things and so on.

I'm obviously going to be faster on the 990, but even then there will be points where I stop or go very slowly. I'd prefer a more accurate reading and will compromise with less points if it is necessary.

ben
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Old 05-24-2014, 07:49 PM   #7
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This sounds more like the problem where the gps is shut off in one location, then started up again some other distant location. The gps includes a straight track from the previous to the current location, causing weird anomalies in the track log and anything else which reports on the data, like average or maximum speed.

As long as you remember to clear the track log and trip computer AFTER the gps has found its new location, you won't see the problem.

On my Montana I have a shortcut to "Reset Trip and Track Data" and I run that at the start of each days ride.
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Old 05-24-2014, 07:58 PM   #8
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This sounds more like the problem where the gps is shut off in one location, then started up again some other distant location. The gps includes a straight track from the previous to the current location, causing weird anomalies in the track log and anything else which reports on the data, like average or maximum speed.

As long as you remember to clear the track log and trip computer AFTER the gps has found its new location, you won't see the problem.

On my Montana I have a shortcut to "Reset Trip and Track Data" and I run that at the start of each days ride.
Yes, I make sure to reset at the start. I've seen the straight line track before and don't have this on my current tracks.

ben
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Old 05-24-2014, 09:40 PM   #9
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So for now I'm going to try 0.01 miles (distance option is in miles only), which equates to about 50 feet. I'll up it to 0.02 if that doesn't improve things and so on.ben
Take a look at some tracks in your Archives and find one where you stopped. You will notice a cluster of track points where there should only be one point.

Set your distance to the radius of the cluster and it should not happen when you stop or go very slow on Mt bike.

Or quit using the 62/78 and go back to the good old reliable 60/76 which do not have the new Garmin Design Feature.
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