GPS Altitude Problems

Jim Bittlestone · Post by **Jim Bittlestone** » Sat Sep 19, 2009 7:41 pm

HI All,
my GPS reckons the take off at Semerwater is at 0ft for some reason? Is this poor coverage or a daft GPS? My max height was 1510ft according to my vario, GPS says 501ft!
Is there anything I can do about this.
The Marske - Whitby flight is similar but overly high. The take off at Marske according to the GPS is 124ft, but ot says my max height was 724ft, when my vario reckond 1010ft for max height and 25ft for take off.
Any help appreciated as my back up does not do heights.
Both flights on XC League.
Cheers
Jim
P.S. Its a garmin 76CSX.

Post by **gary stenhouse** » Sat Sep 19, 2009 7:56 pm

before you take off you will have to zero alt 2 but also for alt 1 you should set it to gps altitude and if this looks wrong one you may not of had gps signal before you took off. so switch on the the gps well before take off and this should help, if not you can manualy change alt 1 to the correct height as this could save your bacon on air space can show you tommorow if your out

cheers gary

Jim Bittlestone · Post by **Jim Bittlestone** » Sat Sep 19, 2009 8:26 pm

Cheers Gary, Ive zero'd alt 2 and set alt 1 to map height, its the GPS that reading strange. 0 ft at Semerwater, 124 ft at Marske
Cheers
Jim

Post by **gary stenhouse** » Sat Sep 19, 2009 9:06 pm

could be knackered and given other false readings i haerd you fluffed your take of at marske and nicked a mountain bike and raced around the cliffs to whitby, then managed a top to bottom fron whitby north to south

Jim Bittlestone · Post by **Jim Bittlestone** » Sat Sep 19, 2009 9:15 pm

just wondering if there is a sensor im blocking or summat. It is barometric it measures? Or gps altitude only? Ill have a read and put my mtn bike back.

Jim Bittlestone · Post by **Jim Bittlestone** » Mon Sep 21, 2009 4:43 pm

My GPS problems persist.
I calibrated the height at take off with help from Chris. Then my trace shows only a height gain of only 977ft compared to my vario reading of 2808ft a.t.o.
Lloyds height gain was 2771ft so the vario reading is correct.
There is a hole at the back of the GPS which I have not blocked which I think is the barometric sensor?
Does anyone have any ideas what is wrong please? (other than my Golden really does have a glide ratio of 50:1?)
Cheers
Jim

Kitt Rudd · Post by **Kitt Rudd** » Mon Sep 21, 2009 4:59 pm

Jim Bittlestone wrote: (other than my Golden really does have a glide ratio of 50:1?)

That will be the Golden 3 proto then Jim . Ondrej had one with him at St Hillaire. Very nearly the finished article so all we need is some good autumn weather at the test centre.

Kitt

Bradleisure · Post by **Bradleisure** » Mon Sep 21, 2009 5:57 pm

Hi Jim

You've probably already done this...

http://www8.garmin.com/support/collecti ... 0-00469-00

Remember to download your flights first as I'm not sure they will be there after the firmware update.

Bradleisure · Post by **Bradleisure** » Mon Sep 21, 2009 6:06 pm

And if I were you I'd set it using GPS to see whether that helps....

Press "MENU", then select "Calibrate Altimeter", then select NO and press ENTER twice to use default GPS elevation. (Give the GPS time to get an accurate reading first as someone has mentioned before)

Just remember that it won't be correct for airspace, you've got your vario for that!

Jim Bittlestone · Post by **Jim Bittlestone** » Mon Sep 21, 2009 6:35 pm

cheers tony ill try that

Jim Bittlestone · Post by **Jim Bittlestone** » Thu Sep 24, 2009 8:05 pm

i tried calibrating the altimeter but it still kept on being strange. I did a hard set on it by pressing page and enter on start up. This seems to have settled it down.
Cheers
Jim

Bradleisure · Post by **Bradleisure** » Thu Sep 24, 2009 9:08 pm

AEFB! always works!

All Else Fails Button.

Either that or a bigger hammer!