Garmin 60csx question

I just received my 60csx. I upgraded it to v2.9, followed by a
master-reset to clear all user settings.

Is there any indication whether the elevation are from the GPS, or
build-in barometer? I know if I turn off the GPS, it will be from the
barometer, but what if I am outside and receiving a perfectly good
signal? Is it then from the GPS? Or a mix of GPS/barometer pressure?
(What if there's poor GPS signal, so the elevation from GPS are
unreliable?)

I also noticed the unit appears to have automatically switched on
road-lock, when I clearly remembered turning it off. This happened
once while I left the unit on to clock how long it lasts on a set of
AA. Has anyone seen this problem?

All in all, I am happy with the performance of the 60csx. It seems a
lot more responsive than the 60cs. It's amazing seeing it shows 10
full bars 2 seconds later after I switch on the GPS.

I do feel like there are some minor glitches, like road-lock
automatically turning on for some reason (data corruption?), and the
position drifts when inside. Seems this unit will consume tracklog
faster than the 60cs.

I read garmin will supposely address the position drift as a firmware
fix, but I don't really know if there's much they can do about it, how
can they know whether the new reading is valid or not?
drifts..

Raymond

nospam.gps@none.com wrote:

The altitude displayed will always be barometer altitude, with two
exceptions:
On the satellite screen, you can hit menu-GPS altitude, and see it
momentarily.
When averaging a waypoint, you are seeing the GPS altitude.

It seems odd that you can't turn that off, the way you can turn off the
compass.

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Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5

dold@xrexxgarmi.usenet.us.com wrote:



In other words, in general, the 60csx will have more accurate
elevation display than the 60cx under simliar conditions? When does
the auto-calibrate kick in?

If I average a location for say 24 hours with good satellite view, how
accurate is the resulting elevation? (I read somewhere that GPS have
vertical accuracy of about 30-40 ft?)

Raymond

nospam.gps@none.com wrote:

I believe that averaging for 1 minute at different times of day and
different days is probably better. I have accumulated 11 such readings
at the same spot on our property over the last two months, usually with
an "accuracy" of 2 or 3 meters. The results of these agree within
+/- 1.5 1.5 3.5 meters in x, y and z.

You certainly want to switch of that barometric altimeter over a long
averaging period as you have no way of getting an accurate altimeter
setting.

My views on barometric altimeters is rather controversial but I have
over 2000 hours of flying time with several hundred hours of that on
instruments and it is my firm belief that anything better than +/-20 ft
on an aircraft quality altimeter is just plain wishful thinking. And
that is only near an airport with a current altimeter setting from the
tower. I also mounted a surplus aircraft altimeter in my car and, in a
drive trough the mountains, saw errors of over 100 feet over a period of
a couple hours.

Looking at the official survey of our lot, I see that the surveyours got
343m at a point where my average is also 343m. My conclusion is a one
minute average with WAAS enabled and working and an "accuracy" reported
by the GPS-V of 2 or 3 meters is better than you are likely to get with
a pressure altimeter off airport.

BTW, I have much the same opinion of the "built in" magnetic compasses.

Ted

I don't think you are wrong, and certainly not controversial. Any hope
that the altimeter in the 60cs is accurate is wishful thinking. It
fluctuates so badly with pressure that I would just as soon turn it off, if
I could. It might be valuable for hiking on a clear day with no pressure
changes, but it is nearly useless to me. When it seems to be way off, I
check the GPS altitude and find a reasonable number. I calibrate it on my
porch rail whenever I intend to use it. If I find some known good
altitude, I might calibrate to that, but usually not.


My gps altitude is generally +/-20 feet to the USGS altitude line that
happens to pass through my property. Today, with an EPE of 8 feet, the
GPS altitude is at 1069 at a point that I have measured repeatedly, and
decided is 1077. The nearby elevation line is 1080, but I'm uphill and a
porch rail above that. I just have never agreed with it.

I don't know what to expect from the horizontal placement of the elevation
lines on a topo map.

I should check the altitude where the line crosses the road, right at an
intersection, so I know that I'm not suffering from a loss of calibration
in the ExpertGPS topo map, although it looks very good.


I find it very accurate just after a calibration. I was obsessive about
noting the alignment of my house, using the original survey of my parcel,
some measurements, and the shadow cast along one wall of the house,
compared to a solar calculation. The 60cs is repeatably as accurate as my
other methods, within one degree.

If I want to use it, I calibrate it at that time. Unlike the altimeter, I
can calibrate it whenever I want, wherever I want. I find it disturbing
that it isn't obvious when it is off by 20 degrees.

I haven't made careful note of whether the calibration is needed each time,
but one or two glaring errors were enough to convince me that it isn't
reliable without a current calibration. I'm not positive that I may have
recharged or changed batteries, or if the batteries might have rotated in
the holders for some reason, destroying the magnetic alignment, or if I am
just subject to some external magnetic deviation.

I find the compass more useful in the 60cs than I would have in my eTrex
yellow. With the 60cs, I might remove it from the dash while stopped to
zoom, change routing, select a new route, whatever. The movement from the
dash is often enough to lose the previous GPS direction arrow, as it thinks
I moved in the other direction a bit. With the compass, I can be somewhat
sure of my orientation, although I do have to lay it flat. With it on the
dash, semi-upright, and the compass in the auto-on mode, I suddenly find
the world skewed, with the road ahead of me oriented at a wrong angle. As
soon as I pick up speed and the GPS heading takes effect, the world is
right again.

With the eTrex yellow, it was less likely to notice the movement away from
the dash, and there were fewer features that required that sort of close up
attention. I would just orient the eTrex in my last known orientation of
travel, and the compass rose would be good, most of the time.

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Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5