Hi Terry,
Seems a long winded way of saying what the difference is - the
atmosphere expands as the temperature increases. I think GPS with
proper modern receivers and good antenna exposure is better than he thinks.
I'd say GPS altitude is rarely more than 50 feet out once the
receiver has been running for more than 10 minutes or so and provided
it has been set up for aviation dynamics. What works in a hang glider
or para glider may not work all that well with sailplane flight
dynamics. The better receivers either configure themselves or let the
instrument manufacturer configure them for the intended use. GPS
ain't just GPS.
It is correct that you must use pressure altitude for airspace
compliance as the difference between pressure altitude and GPS
altitude can be quite large, however as the glider only notices
geometric altitude for final glides GPS altitude is better for this.
If you think you can even get the pressure altitude to within 50 feet
of what it really is in a glider cockpit using an untested static
source or cockpit static (or even the certified static on some
gliders) plus unknown temperature offset and aging drifts on the
altitude sensor,
you don't understand the problem. You should be using some form of
total energy compensation on the altitude required for final glide
otherwise it is hard to tell what is going on during pull ups and
push overs. This can be done with modern GPS units as well as with p.a.
We did some issues with GPS altitude from some early flight recorders
which heavily smoothed the GPS altitude. For this reason and others
we incorporated the GPS in the system from the B500 on as we can then
setup the GPS properly and interface it just once.
Mike
. At 12:58 PM 27/02/2014, you wrote:
Thanks Mike, it's amazing how serial com. devices still live on (not
that I'm complaining - we still use them in some areas of amateur radio).
I followed the link you identified and found
<http://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/>this
article from other links in that site.
Quite interesting also - at least I thought so 8-) .
regards
TN
On 27/02/2014 9:05 AM, Mike Borgelt wrote:
Those wanting to use Android devices with serial inputs can buy an
Androport from GliderTools www.glidertools.com
Two RS232 inputs to Android. I have been told it all works with a
B500 and Flarm so should be no problem with any of our data output varios.
Saves messing around with building IOIO boards etc. In nice shielded box.
Mike
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
_______________________________________________
Aus-soaring mailing list
<mailto:[email protected]>[email protected]
To check or change subscription details, visit:
<http://lists.internode.on.net/mailman/listinfo/aus-soaring>http://lists.internode.on.net/mailman/listinfo/aus-soaring
_______________________________________________
Aus-soaring mailing list
[email protected]
To check or change subscription details, visit:
http://lists.internode.on.net/mailman/listinfo/aus-soaring
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
_______________________________________________
Aus-soaring mailing list
[email protected]
To check or change subscription details, visit:
http://lists.internode.on.net/mailman/listinfo/aus-soaring
