Re: Garmin GPS-18 with prn 42 and 50, no DGPS.

On Oct 26, 3:23 am, Doug Gray <d...@xxxxxxxxxxxxxxxxxxxxx> wrote:
On Thu, 25 Oct 2007 18:24:32 -0700, Jon wrote:
On Oct 24, 5:54 pm, Doug Gray <d...@xxxxxxxxxxxxxxxxxxxxx> wrote:
On Wed, 24 Oct 2007 19:35:14 +0000, Sam Wormley wrote:
The "reference receiver" is a network of ground stations. The WAAS
differential corrections, based on that reference network, are valid
for a WAAS (SBAS) enabled GPS receivers that is within or spatially
close to the associated reference network.

Agreed, Australia does not have the network of ground stations to compile
the corrections data nor does our aviation administrator or government
have the desire to put this in place. Goodness knows why!

http://astra.aero/faq.aspxvery unimpressive! Our problem though.

While it is true that there's no intention of putting SBAS in place,
there is other work going on in the area of GPS augmentation.
Airservices Australia (AsA) has begun deploying GBAS and are also
planning to deploy GRAS (Ground Based Regional Augmentation System).
...some snipped
.. My guess as to why they are primarily targeting the aviation
mode at this time, is that it currently makes the most sense from a
business perspective (AsA is a semi-privatized organization).

So why has the SBAS solution been abandoned?

Is there a technical reason or is it simply that AsA is so self serving.

I don't work for them (I'm in the U.S.) so you might be better asking
them.
The first "A' in AsA does stand for "Air", though ;) So one could
expect that
they'd be self-serving to their own mode of transportation.

Recall that the primary application of WAAS is to support the
Approach phase-of-flight. So, one technical reason I can think of is
that there's simply no justification for a Wide Area since the
airports are
located around the perimeter of the continent. Over the "middle" (once
you
get ~100MN inland?) of the continent, most/all flights in the airspace
are
going to be in the EnRoute phase-of-flight. Standalone GPS is
sufficient to
provide the required performance for that phase.

I'll bet not one single aircraft leaves the ground that does not have a
GPS of one form or another on the flight deck, and very soon most of these
will be SBAS enabled. Yet AsA has decreed that they're not worthy
of consideration.

I'm not sure of the actual equipage statistics, but SBAS isn't a slam
dunk for
the big airlines due to cost. The cost of equippage of just one plane
is not trivial:

- plane is taken out of service for the install/certify so there's
lost revenue
- certified avionics receiver for is typically 5 figures minimum
- the certify of the install can be expensive depending upon what else
is being done

Ok, so figure something on the order of possibly 6 figures to upgrade
*one* plane.
Now, consider there are craft in the fleet that already have something
that gives them
equivalent or better performance, e.g. ILS, and you can see why the
airlines simply
aren't flocking to upgrade all that quickly.

It would not be at all difficult to roll out sufficient ground reference
sites networked back to the satellite ground station to up-link correction
data. They could be located at airfields (zero cost to AsA there),
surveyed accurately and equipped with a high resolution GPS and modest
processing power.

Locating reference stations at an airfield pretty much amounts to
GBAS.

GRAS is a nice happy medium, I think, and they've done a fair amount
of research
over several years to make a good business case and of course be able
to prove it's
safe. It puts the ground network in where it's going to benefit the
most. That' said, once
they start to gain operational experience with it, they may find that
expanding the network
is a Good Thing and more area of the continent will be supported.

Am I oversimplifying this? I think we could ignore tectonic plate
movement so there is no need to over kill.

The rest of the infrastructure is already there thanks of course to the US
and Japanese.

Hmm.. election time - which minister do I need to talk to?

Dunno, mate ;)

Every time I see the word 'minister' , I always think of Monty
Python's "Ministry of silly walks"

:D

Doug

Regards,
Jon

.

Relevant Pages

  • Re: Garmin GPS-18 with prn 42 and 50, no DGPS.
    ... differential corrections, based on that reference network, are valid ... While it is true that there's no intention of putting SBAS in place, ... there is other work going on in the area of GPS augmentation. ... Airservices Australia (AsA) has begun deploying GBAS and are also ...
    (sci.geo.satellite-nav)
  • Re: GPS Cellphone Tracking - Track Anyone Anytime Anywhere
    ... >GSM mobile phone tracking system via the GPS-TRACK satellite network. ... I am presuming that the phone constantly sends via GSM its GPS location. ... Some phones do have some GPS functionality built in but use the communication with the network to actually calculate the position of the handset. ... That is a form of tagging but mobile phone records can be used to work out roughly where the phone is. ...
    (uk.rec.walking)
  • Re: ESTB/EGNOS works. :-)
    ... SBAS and a nearby reference station is larger than what I get the few ... I have actually been in a situation once where a meter-level GPS would ... a very dense fog bank. ... > For true open water navigation, the advantage of using a GPS is obvoius ...
    (sci.geo.satellite-nav)
  • Re: GPS Data Bandwidth Usage
    ... a Motorola Datatec 900 MHz network. ... transmit time on the field systems. ... GPS Settings within PEN.INI ... data to the UCAD server which creates RF traffic. ...
    (sci.geo.satellite-nav)
  • Re: GPS Unit for Timekeeping on Linux?
    ... >>Doesn't that imply that I'm in constant communication with some remote ... GPS will get you time to within a second, ... > Now, if you can't ever connect to a global network, then something like ... Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) ...
    (sci.geo.satellite-nav)