How different is aviation GPS?

B A R R Y wrote:
Matt Barrow wrote:

WAAS will provide about 10 feet, but that only for approaches with
WAAS augmentation.


WAAS actually works anytime the satellite correction signal is
available, you don't have to be flying an approach.

My Garmin 60CS, as well the eTrex Vista I previously owned, both use
WAAS corrections. I can't remember the last time I didn't get the
corrections.

A friend bought a 60CS recently and we noticed that my old Garmin-12 got
better reception and seemed more accurate. We called Garmin and the
fellow we talk with was surprised because both units use the same chips
inside!

In a previous article, B A R R Y said:
My Garmin 60CS, as well the eTrex Vista I previously owned, both use
WAAS corrections. I can't remember the last time I didn't get the
corrections.

I have a Garmin 296 with WAAS, and I get WAAS nearly every time when I'm
flying (but not always), but I only seem to get it about half the time
when I'm driving. But I live, fly and drive up near the Canadian border,
so maybe the coverage isn't as good up here.

--
Paul Tomblin http://xcski.com/blogs/pt/
Real Time, adj.:
Here and now, as opposed to fake time, which only occurs there and then.

Matt Barrow wrote:

Aircraft GPS systems are accurate to about 30 feet; how well do you think
that would work if your building a bridge, or more importantly, a tunnel?


If I was owner, I'd end up with two tunnels for the price of one

Ramapriya

wrote in message
oups.com...
Matt Barrow wrote:

Aircraft GPS systems are accurate to about 30 feet; how well do you think
that would work if your building a bridge, or more importantly, a tunnel?


If I was owner, I'd end up with two tunnels for the price of one

One tunnel, two lanes. :~&

wrote:
As part of my work (civil engineer), I routinely use GPS equipment in
surveying. And construction specifications usually calls for this
equipment to be held stationary for as much as three hours where
crucial transition points are to be located, and for up to twenty
minutes at less important locations.

I guess since you folk use GPS to navigate all across the globe and
requires to be both very precise and instantaneous, my equipment is
very much inferior to what's used in aviation.

Has anyone here used the type of equipment I'm mentioning? You should
see the time the thing I use takes to stabilize itself to show the
elevation... you'd comfortably CFIT if you had that in your airplane
)

Ramapriya


In addition to what every one else mentioned, aviation GPS also has a
feature known as RAIM which stands for Receiver Autonomous Integrity
Monitoring. It warns you of any problems with the satellite signals.
Some have RAIM prediction as well.

("Andrew Sarangan" wrote)
In addition to what every one else mentioned, aviation GPS also has a
feature known as RAIM which stands for Receiver Autonomous Integrity
Monitoring. It warns you of any problems with the satellite signals. Some
have RAIM prediction as well.


How does RAIM prediction work, I wonder?

The GPS unit knows where you are, knows where you're heading, and knows
where x number of signals will be - based on the satellites' "predictable"
orbits.... g

Ok. No clue.


Montblack

"Montblack" wrote in message
...
based on the satellites' "predictable" orbits.... g

Ok. No clue.


Montblack

This is know as the 'ephemeris'.