Jump to content

Anyone here calibrate their Garmin 60CSX's altimeter?


Recommended Posts

I never did, but I'm thinking maybe I should just to ensure the most accurate readings? Anyone here tried it? Was it easy to do?

Actually I was going to calibrate mine, but found out it was dead on accurate with elevation & pressure so I never did. It did seem easy enough to do though from reading the manual.

Link to comment

It is very easy to do, you either need to know the correct elevation or barometric pressure at your current location. If you go to Setup>Calibration>Altimeter it will ask for elevation or pressure. Input one and you are on your way. The easiest for me is usually elevation, if you can pick it off a topo map or have some other reliable reference.

Link to comment

If you happen to know the exact elevation of your location, it's worth calibrating the altimeter. This will give you very accurate elevation data for the next few minutes, or hours, if the barometric pressure doesn't change. If the pressure changes, accuracy will decrease.

 

Most of the time the auto-calibration feature works fine. Over a certain time, the software averages the elevation readings from GPS data. The altimeter is good for plotting small changes of elevation over a short period, whereas the GPS data will give you better absolute elevation date averaged over a longer period. Working with just an altimeter, you might be very accurate at the beginning of the day, just after calibrating it, but way off at the end of the day because the weather has changed. Using only GPS data, you might see the elevation reading jump up and down in the space of a few minutes, depending on satellite reception, but it will have more or less the same accuracy at the beginning and at the end of the day. The auto-calibration feature puts both techniques together to give both short-term and long-term accuracy: it seems to do the job well.

Link to comment

I never did, but I'm thinking maybe I should just to ensure the most accurate readings? Anyone here tried it? Was it easy to do?

If accurate elevation information is important to you, it's a good idea to calibrate the altimeter manually when you first turn on the unit, but after it has acquired a good lock. Some say that the elevation affects the horizontal accuracy, but I have never seen any evidence of that.

 

If you have auto calibration turned on, it will normally get your altimeter within about 30 feet of the correct elevation within about 30 minutes after you turn the unit on and it acquires a lock, faster if you have been using the unit within a few hours previous. However, auto calibration can only work when the unit has a lock; so if the unit is off over night, the elevation may be hundreds of feet off when you first turn it on the next day.

 

If you know your elevation, even if it’s just from a topo map or from the elevation reading you noted at the end of the previous day, calibrating to that will generally give you the most accurate calibration. If you know the actual elevation, so much the better. If you don’t, you can calibrate to a barometric pressure reading within about 25 miles to get a pretty good initial calibration. If that isn’t available, calibrating to GPS elevation (one of the options offered) will get you “in the ballpark” more quickly than just waiting for auto calibration to do it.

 

Anyone interested in more information on this topic might want to search for the many excellent posts by julianh, which you can do from a link on his profile page.

Edited by roybassist
Link to comment

It surprises me that no one mentioned another setting..... Variable Elev / Fixed Elev

 

As mentioned above, calibrate to a / your Known elevation or pressure.

 

Travel with the unit set on Auto Calibration. (GPS corrects for pressure changes)and another setting...Variable Elevation

 

At the end of the day (camp/motel,etc) change your unit setting to Fixed Elevation. That way, weather/pressure changes don't affect elevation displayed. The pressure can change but the reported elevation should stay the same overnight.

 

Before you start out again, change unit setting back to Auto Calibration and Variable Elev

 

It works, but only if you remember each time.......I don't ....,so I just leave mine on autocalibration and Variable, and know that it will likely be incorrect for a while after I first turn it on.

Edited by Grasscatcher
Link to comment

How accurate is the elevation the unit calculates when using the satelites on the satelite page? I think it should be pretty good and why not just use it for the "known elevation" to input and calibrate the other altimeter.

If you have a GOOD 3D lock (i.e. good sky view, good spread of satellites, no multi-oath, etc), and give the unit a few minutes to settle down before calibrating the altimeter, then the GPS elevation is USUALLY pretty good - say +/- 10 metres or so. If you don't know your "true" elevation, this is in fact the best way of performing an initial calibration.

 

However, if you don't wait for the 3D fix to settle down, and / or if you are in a situation with poor reception conditions (e.g. heavy tree cover, deep in the "urban jungle", etc), the GPS elevation can easily be out by 20 metres, 50 metres, or even more.

Link to comment

I don't have any maps to help me determine my elevation. I'm currently in Vancouver, Canada. Any suggestions on how to get this started?

 

Try going to a local airport, any size, and ask them for their elevation. Any pilot there or person who works behind the desk in a small airport will know. You can also find this out on the 'net. Bring your GPS with you and set your known altitude that way. Head straight home and check your reading there and keep it for reference.

 

If you let me know the name and city/town of your airport and I'll try to get the info for you.

 

DG

Link to comment

I don't have any maps to help me determine my elevation. I'm currently in Vancouver, Canada. Any suggestions on how to get this started?

 

You can always use sea level and most airports have their altitude posted on the big sign near the entrance. I believe that indicates the highest point on the field so it could be off at the sign. I dug out an old WAC E 16 aeronautical map for Vancouver Int. and it indicated 308 feet if I picked the right number from all the clutter. That sounds about right. Belligham indicated 158 feet. Also if you have a radio that will tune to the aeronautical frequencies, the tower gives the current altimeter setting. Dick

 

Sorry, looks like my 308 was incorrect. I found two others 2M or 6 Feet. I did a search listed in my last reply a elevation of 14 feet aMSL

Edited by W7WT
Link to comment

Found two slightly different answers. One was 2 meters or 6 feet. This was the other that I found when doing a search.

 

Vancouver International Airport

Vancouver, British Columbia, Canada

 

IATA (Airline) Code: YVR

ICAO (4-Letter) Code: CYVR

Website: www.yvr.ca

E-mail: cargo@yvr.ca or rob_ellaway@yvr.ca

Telephone: +1 (1)604 276-6500, +1 (1)604 276-6326, (Aviation Marketing) +1 (1)604 276-6316

Time Zone: GMT-8

Latitude: N 49.193890

Longitude: W 123.184441

Elevation: 14ft aMSL

Link to comment

It surprises me that no one mentioned another setting..... Variable Elev / Fixed Elev

 

As mentioned above, calibrate to a / your Known elevation or pressure.

 

Travel with the unit set on Auto Calibration. (GPS corrects for pressure changes)and another setting...Variable Elevation

 

At the end of the day (camp/motel,etc) change your unit setting to Fixed Elevation. That way, weather/pressure changes don't affect elevation displayed. The pressure can change but the reported elevation should stay the same overnight.

 

Yes, that's how it logically ought to work: the reported elevation should stay the same when the unit is set to "Fixed Elevation". But it doesn't. I set my unit to Fixed Elevation and see the elevation display changing.

 

This happens even if GPS reception is turned off, so it seems that the barometer reading is still affecting the elevation reading, even though the idea of "Fixed Elevation" is to pin down the elevation reading so that pressure changes are only seen in the barometer display. I've never been able to find out why this is: Garmin tech support was unable to tell me, and nobody else has come up with an explanation.

 

So I've given up using Fixed Elevation. I keep the Variable Elevation setting and I usually leave auto-calibration on: in areas with good satellite reception I find it gives results very close to known altitude values.

Link to comment

From an airport close to my place I get current barometric pressure 1002,9 mBar. This value is the "QNH"-value, e.g. the for me unknown value that was noted at the airport has been been recalculated to be correct as if measured at the mean sea level.

 

In my Garmin Etrex Vista Hcx there are two pressures present, the barometric and the ambient. When calibrating the altimeter by putting in a mBar value it is, as I understand, the barometric value that is the correct input.

 

The difference between the barometric value (mean sea value) and the ambient value gives the altitute above meas sea level of the Garmin gadget.

 

I have found out that I must add 1,4 mBar to this value, the barometric airport value (1002,9 mBar) and the new corrected value is 1004,3 mBar.

 

After I have entered the corrected value in Garmin Etrex Vista Hcx I receive the altitude to 20 meter which is the correct altitude for the Garmin above the mean sea level (when placed on my kitchen table).

 

The accuracy specified is plus minus 10 feet (ca plus minus 3 meter) but 1,4 mBar is around 11 meter.

 

Has this needed correction been noted by someone else or discussed earlier?

 

Cheers!

 

... and Happy New Year !!

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...