60CSx Total Ascent

[wingpeople]

I noticed that my "Total Ascent" figure was off by several hundred feet at the end of the day.  Is this a known problem/anomoly?  Guessed it was because the unit is always "averaging?" to determine your current elevation and that is what gets added to the Total Ascent figure.   Suggestions?   I do reset the unit at the trailhead.

[-Oz-]

How do you know what your actual total ascent is?

Don't forget that it uses the barometer which is technically more accurate than the GPS but has been known to have some anomolies. 

How many is several hunder 300 or 900?

[wingpeople]

I have the USGS topo maps and can easily compute my total gain from them.  First day I gained 2,800 (per map), GPS read 4,600 total ascent.   Next day I gained 3,300 (per map) and GPS read 3,700.  Weather seemed stable so don't know if there was a major barometric change.

[-Oz-]

I would honestly say that the GPS might be a bit more accurate but I really don't know.

[onomou]

Did you calibrate your altimeter to begin with? I have noticed that my altimeter and compass both get off pretty quickly after calibration (sometimes as little as a week). I have also noticed that if the GPS loses signal for a short bit things can jump around a lot, giving some pretty funny looking tracks when I was actually going straight.

[BKSLDR7]

I too noticed some jumping when the GPSr momentarily loses
the signal or the signal degrades even briefly due to
buildings or trees or whatever. I wouldn't think that that would
throw off an average as long as you have lots of points unless
your signal is really degraded.

I would agree with onomou.  Check your barometer calibration.
Even so sometimes elevation change is calculated by the GPSr
using both GPS and Barometric data so this should compensate
somewhat for a barometric calibration error.
From what I read it should be a lot closer!

Take a look at this
http://blog.mtbguru.com/2006/12/17/elevation-accuracy/

GPS lat/long/elevation should all have an accuracy of around 30 meters(~100')

[-Oz-]

yea, but that unit uses a barometer so it should be more accurate than 100'