[OSM-talk] Quality of Sirf star 3 tracks disappointing...

[Nick Black]

On 7/11/06, Andy Robinson <Andy_J_Robinson at blueyonder.co.uk> wrote:
> Yes, if you are seeing D's on the satellite bars when WAAS is enabled you
> are picking up the EGNOS (or WAAS) transmissions and the data for the
> satellite with the D is receiving corrections. On Garmin units. Sat 33, 37
> and 39 currently make up the EGNOS platform and normally two channels of the
> GPS receiver are reserved for two of these when SBAS (Satellite Based
> Augmentation System, ie WAAS or EGNOS) is enabled. WAAS and EGNOS do the
> same thing. Just that WAAS is for the Americas and EGNOS for Europe and
> Africa. The Japanese system is not up and running yet.
>
> The EGNOS platform is just this month moving from test mode to initial
> operations mode when the correction data should be available all the time.
>
> For more about SBAS check out this useful site:
>
> http://www.kowoma.de/en/gps/waas_egnos.htm

Thanks Andy - that site has answered a lot of my questions about what
is going on.  I was wondering why the PRN on my Garmin didnt match the
'real' PRN of the satellite, looks like Garmin determin their own.


Cheers,

Nick


>
> Cheers,
>
> Andy
>
> Andy Robinson
> Andy_J_Robinson at blueyonder.co.uk
>
> >-----Original Message-----
> >From: talk-bounces at openstreetmap.org [mailto:talk-
> >bounces at openstreetmap.org] On Behalf Of Nick Black
> >Sent: 11 July 2006 09:31
> >To: Barnett, Phillip
> >Cc: talk at openstreetmap.org
> >Subject: Re: [OSM-talk] Quality of Sirf star 3 tracks disappointing...
> >
> >On 7/10/06, Barnett, Phillip <Phillip.Barnett at itn.co.uk> wrote:
> >>
> >>
> >>
> >> Yep, D's in the bars mean you're picking up WAAS/EGNOS signals from those
> >> satellites.
> >> Phillip
> >
> >I dont know exactly what the "D" means, but I dont think they mean
> >that the receiver is picking up EGNOS signals from NAVSTAR (GPS).
> >There are three satellites that currently make up the EGNOS system, in
> >geostaionary orbit so that they can broadcast over Europe.  The three
> >satallites really do very little (compared to a NAVSTAR, GLONASS or
> >GALILEO) satellite.  'All' they do is receive a broadcast signal from
> >European (ESA controlled) monitoring stations, and relay the signal
> >back to Earth, where it can be reiceived and understood by compatible
> >GPS receivers.
> >
> >The signal contains precise inforamtion about the orbit (ephemeris) of
> >GPS and GLONASS satellites, about ionospheric interference and about
> >the accuracy of the atomic clocks onboard the Navstar satellites. In
> >this way the system differs from Differential GPS and from A-GPS.
> >D-GPS works by 'averaging out' errors by placing a super accurate
> >receiver over a known position and relaying the differentials to a
> >less accurate reciever.  EGNOS is a lot more intelligent than that as
> >it deals with live data relating to various conditions.
> >
> >I am still uncertain whether I have ever picked up an EGNOS signal.  I
> >have a Garmin GPS 60 which, according to ESA
> >(http://esamultimedia.esa.int/docs/egnos/estb/SBAS_receivers.pdf)
> >isn't supported.  The manual however says the unit does support EGNOS
> >and WAAS.  I also noticed the "D"s the other day, when I was on a
> >south facing hill, so I dont think that its a coincidence.  I think
> >its more likely that the Ds mean that the reciever has picked up the
> >correction information for that satellite.  Anyone got anymore ideas?
> >
> >Nick
> >
> >
> >
> >
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: talk-bounces at openstreetmap.org on behalf of Jon Stockill
> >> Sent: Mon 7/10/2006 11:15 PM
> >> To: talk at openstreetmap.org
> >> Subject: Re: [OSM-talk] Quality of Sirf star 3 tracks disappointing...
> >>
> >> Lars Aronsson wrote:
> >>
> >> > With time and experience, I've come to use the satellite view
> >> > (showing signal strengths) on my Garmin while I'm moving around.
> >> > It's no point in running around if no signal is received.
> >>
> >> I was doing that at the weekend when I noticed little D's appear on all
> >> the signal strength bars on my GPS60 - this isn't mentioned in the
> >> manual, but I guess it means WAAS was working - because the error
> >> estimate shown at the top of the page dropped to 2m - definitely the
> >> most accurate coverage I've ever seen. Definitely a good upgrade from my
> >> old GPS12 - the screen is MUCH nicer, the battery life longer (on half
> >> the number of cells) and it'll store 10,000 trackpoints rather than
> >> 1024. Not only that, but I find it incredibly useful to save the tracks
> >> (after downloading of course) as it then gives you a reference on the
> >> map view for where you've already been.
> >>
> >> Jon
> >>
> >> _______________________________________________
> >> talk mailing list
> >> talk at openstreetmap.org
> >> http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
> >>
> >>
> >>
> >> Phillip
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: talk-bounces at openstreetmap.org on behalf of Jon Stockill
> >> Sent: Mon 7/10/2006 11:15 PM
> >> To: talk at openstreetmap.org
> >> Subject: Re: [OSM-talk] Quality of Sirf star 3 tracks disappointing...
> >>
> >> Lars Aronsson wrote:
> >>
> >> > With time and experience, I've come to use the satellite view
> >> > (showing signal strengths) on my Garmin while I'm moving around.
> >> > It's no point in running around if no signal is received.
> >>
> >> I was doing that at the weekend when I noticed little D's appear on all
> >> the signal strength bars on my GPS60 - this isn't mentioned in the
> >> manual, but I guess it means WAAS was working - because the error
> >> estimate shown at the top of the page dropped to 2m - definitely the
> >> most accurate coverage I've ever seen. Definitely a good upgrade from my
> >> old GPS12 - the screen is MUCH nicer, the battery life longer (on half
> >> the number of cells) and it'll store 10,000 trackpoints rather than
> >> 1024. Not only that, but I find it incredibly useful to save the tracks
> >> (after downloading of course) as it then gives you a reference on the
> >> map view for where you've already been.
> >>
> >> Jon
> >>
> >> _______________________________________________
> >> talk mailing list
> >> talk at openstreetmap.org
> >> http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
> >>
> >>
> >>
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