It tracked within 30 seconds giving a first position with 4 (albeit
high) satellites. GLONASS tracked into the solution immediately as well
with 5 satellites in view.

I guess the Almanac was recent and saved in flash.

Within a couple minutes it was tracking:

8 GPS
1 WAAS
5 GLONASS

estimating error of 3 - 4 metres. (Pretty strong building mask to the
SE). I'll go to a high point asap to see what it can really pull in.

The "basemap" is pretty disappointing. Guess I'll have to roll my own
or buy some for it.

Was outside for about 3 minutes so left it outside for another 12.5
minutes to be sure of a freshly loaded GPS Almanac (I have no idea how
long the GLONASS Almanac takes to load...).

--
gmail originated posts filtered due to spam.

Alan Browne <(E-Mail Removed)> writes:

> The "basemap" is pretty disappointing. Guess I'll have to roll my own
> or buy some for it.

I'm not surprised; the basemap on the Etrex Vista HCx and the Oregon 450
is also highly limited. On both of those I've been using OpenStreetmap
data compiled with mkgmap plus contours from gisfiledepot, and aside
From addresses and POI data it generally seems better than the
proprietary map data.

Is there a way to disable GPS and just use GLONASS? I'm not sure
that's useful, but it would be interesting.


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On 22 Nov, 20:05, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:
> It tracked within 30 seconds giving a first position with 4 (albeit
> high) satellites. *GLONASS tracked into the solution immediately as well
> with 5 satellites in view.
>
> I guess the Almanac was recent and saved in flash.
>
> Within a couple minutes it was tracking:
>
> 8 GPS
> 1 WAAS
> 5 GLONASS
>
> estimating error of 3 - 4 metres. *(Pretty strong building mask to the
> SE). *I'll go to a high point asap to see what it can really pull in.
>
> The "basemap" is pretty disappointing. *Guess I'll have to roll my own
> or buy some for it.
>
> Was outside for about 3 minutes so left it outside for another 12.5
> minutes to be sure of a freshly loaded GPS Almanac (I have no idea how
> long the GLONASS Almanac takes to load...).

Glonass Almanac takes only 2.5 minutes to load.

On 2011-11-22 18:35 , Greg Troxel wrote:
>
> Alan Browne<(E-Mail Removed)> writes:
>
>> The "basemap" is pretty disappointing. Guess I'll have to roll my own
>> or buy some for it.
>
> I'm not surprised; the basemap on the Etrex Vista HCx and the Oregon 450
> is also highly limited. On both of those I've been using OpenStreetmap
> data compiled with mkgmap plus contours from gisfiledepot, and aside
> From addresses and POI data it generally seems better than the
> proprietary map data.

I'll be looking into that soon. There are some 1:50,000 maps I have
that I may try scanning and registering. Both L/L and UTM so should be
easy to register.

> Is there a way to disable GPS and just use GLONASS? I'm not sure
> that's useful, but it would be interesting.

It can run as GPS or GPS+GLONASS only. Too bad - I think it would be
interesting too.

--
gmail originated posts filtered due to spam.

On Nov 23, 9:15*am, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:
> On 2011-11-22 18:35 , Greg Troxel wrote:
>
>
>
> > Is there a way to disable GPS and just use GLONASS? * I'm not sure
> > that's useful, but it would be interesting.
>
> It can run as GPS or GPS+GLONASS only. *Too bad - I think it would be
> interesting too.
>
> --
Actually, would be nice if it provided GPS, GLONASS, GPS+GLONASS,
WAAS on/off. Shame there's now way to see NMEA fix data to evaluate
its characteristics.

Obviously it's not marketed to those analytically inclined. I'm sure
it will serve you well after the appropriate maps are installed.

--- CHAS

On 2011-11-23 10:58 , HIPAR wrote:
> On Nov 23, 9:15 am, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> wrote:
>> On 2011-11-22 18:35 , Greg Troxel wrote:
>>
>>
>>
>>> Is there a way to disable GPS and just use GLONASS? I'm not sure
>>> that's useful, but it would be interesting.
>>
>> It can run as GPS or GPS+GLONASS only. Too bad - I think it would be
>> interesting too.
>>
>> --
> Actually, would be nice if it provided GPS, GLONASS, GPS+GLONASS,
> WAAS on/off. Shame there's now way to see NMEA fix data to evaluate
> its characteristics.

I can shut off WAAS and then compare the GPS and GPS+GLONASS.

Can't get at the internals which is a ****er.

I can record tracks and I know a few ground truths nearby that I can see
on Google Earth to about 1 - 2 metres. So I can go make separate
recordings there in 4 operating states:

GPS
GPS+GLONASS
GPS+WAAS
GPS+WAAS+GLONASS.

I suspect that in the last case the GLONASS could actually reduce the
position quality.

I'm a bit confused over whether EGNOS actually aides GLONASS receivers.
Per the esa article EGNOS does receive GLONASS signals on the ground.
It's not clear if those are DL'd in the EGNOS message to GPS receivers
and how that would be communicated to a GLONASS receiver. No indication
that the Etrex 30 takes the EGNOS corrections for GLONASS to its GLONASS
receiver...

Or perhaps it's just measuring the GLONASS to determine iono
characteristics on the path from the sat to the groundstations and using
that for the benefit of GPS/EGNOS delay computations.

And I'm not in Europe so I can't play with it...

esa article:
http://www.esa.int/esaNA/GGGQI950NDC_egnos_0.html

--
gmail originated posts filtered due to spam.

On Nov 23, 4:26*pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:
> I can shut off WAAS and then compare the GPS and GPS+GLONASS.
>
> Can't get at the internals which is a ****er.
>
> I can record tracks and I know a few ground truths nearby that I can see
> on Google Earth to about 1 - 2 metres. *So I can go make separate
> recordings there in 4 operating states:
>
> GPS
> GPS+GLONASS
> GPS+WAAS
> GPS+WAAS+GLONASS.
>
> I suspect that in the last case the GLONASS could actually reduce the
> position quality.
>
> I'm a bit confused over whether EGNOS actually aides GLONASS receivers.
> * Per the esa article EGNOS does receive GLONASS signals on the ground.
> * It's not clear if those are DL'd in the EGNOS message to GPS receivers
> and how that would be communicated to a GLONASS receiver. *No indication
> that the Etrex 30 takes the EGNOS corrections for GLONASS to its GLONASS
> receiver...
>
> Or perhaps it's just measuring the GLONASS to determine iono
> characteristics on the path from the sat to the groundstations and using
> that for the benefit of GPS/EGNOS delay computations.
>
> And I'm not in Europe so I can't play with it...
>
> esa article:http://www.esa.int/esaNA/GGGQI950NDC_egnos_0.html
>
> --
> gmail originated posts filtered due to spam.

I googled: egnos glonass corrections
The second response:
http://www.egnos-pro.esa.int/ESTB-EG...20May%2006.pdf

Excerpt:
1.
How does an SBAS (Satellite Based Augmentation System) system work?
SBAS systems improve the performances of GPS with the objective to
make it
useable for safety critical services. This is accomplished by
providing, by means
of separate (geostationary) signals of a set of corrections that
improve the
position and time calculation performed by the user satellite
receiver. EGNOS
provides these corrections not only for GPS but also for GLONASS.

So unless ESA (European Space Agency) has no idea what they're talking
about, EGNOS does provide corrections for GLONASS, besides taking
advantage of GLONASS satellites to better sample the ionosphere.


If that 2-3 meter uncertainty is 80% RMS, than its inline with actual
WAAS+GPS performance (GLONASS isn't making it worse). Looks very good
to me.

With an abundance of satellites in view, the unit should be able to
weigh satellites that match each other and exclude/de weight the
others, regardless if they're GPS or GLONASS. The interesting question
is does it bother to do it. A RAIM algorithm of sorts.

The other very interesting test is to drive in downtown areas with
tall buildings all around and see if the unit can keep 5+ birds in
view at all time, that's the major value of GPS+GLONASS for a non
safety of life/not high accuracy unit.

Marcelo Pacheco

On 2011-11-23 15:50 , macpacheco wrote:
> On Nov 23, 4:26 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> wrote:
>> I can shut off WAAS and then compare the GPS and GPS+GLONASS.
>>
>> Can't get at the internals which is a ****er.
>>
>> I can record tracks and I know a few ground truths nearby that I can see
>> on Google Earth to about 1 - 2 metres. So I can go make separate
>> recordings there in 4 operating states:
>>
>> GPS
>> GPS+GLONASS
>> GPS+WAAS
>> GPS+WAAS+GLONASS.
>>
>> I suspect that in the last case the GLONASS could actually reduce the
>> position quality.
>>
>> I'm a bit confused over whether EGNOS actually aides GLONASS receivers.
>> Per the esa article EGNOS does receive GLONASS signals on the ground.
>> It's not clear if those are DL'd in the EGNOS message to GPS receivers
>> and how that would be communicated to a GLONASS receiver. No indication
>> that the Etrex 30 takes the EGNOS corrections for GLONASS to its GLONASS
>> receiver...
>>
>> Or perhaps it's just measuring the GLONASS to determine iono
>> characteristics on the path from the sat to the groundstations and using
>> that for the benefit of GPS/EGNOS delay computations.
>>
>> And I'm not in Europe so I can't play with it...
>>
>> esa article:http://www.esa.int/esaNA/GGGQI950NDC_egnos_0.html
>>
>> --
>> gmail originated posts filtered due to spam.
>
> I googled: egnos glonass corrections
> The second response:
> http://www.egnos-pro.esa.int/ESTB-EG...20May%2006.pdf
>
> Excerpt:
> 1.
> How does an SBAS (Satellite Based Augmentation System) system work?
> SBAS systems improve the performances of GPS with the objective to
> make it
> useable for safety critical services. This is accomplished by
> providing, by means
> of separate (geostationary) signals of a set of corrections that
> improve the
> position and time calculation performed by the user satellite
> receiver. EGNOS
> provides these corrections not only for GPS but also for GLONASS.
>
> So unless ESA (European Space Agency) has no idea what they're talking
> about, EGNOS does provide corrections for GLONASS, besides taking
> advantage of GLONASS satellites to better sample the ionosphere.

How does it transmit them? Does EGNOS broadcast on a frequency and
modulation that GLONASS can pickup?

>
>
> If that 2-3 meter uncertainty is 80% RMS, than its inline with actual
> WAAS+GPS performance (GLONASS isn't making it worse). Looks very good
> to me.

What 2-3 meter uncertainty?



>
> With an abundance of satellites in view, the unit should be able to
> weigh satellites that match each other and exclude/de weight the
> others, regardless if they're GPS or GLONASS. The interesting question
> is does it bother to do it. A RAIM algorithm of sorts.

Would be nice. Garmin are mum on how they mix the data.

> The other very interesting test is to drive in downtown areas with
> tall buildings all around and see if the unit can keep 5+ birds in
> view at all time, that's the major value of GPS+GLONASS for a non
> safety of life/not high accuracy unit.

Keeping birds "in view" in urban canyons may be more a measure of
failure than success. Recent GPS receivers, esp. for hiking, have
become very sensitive in order to get better performance in the woods.
This also increases susceptibility to multipath.

--
gmail originated posts filtered due to spam.

On Nov 23, 7:08*pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:
> > Excerpt:
> > 1.
> > How does an SBAS (Satellite Based Augmentation System) system work?
> > SBAS systems improve the performances of GPS with the objective to
> > make it
> > useable for safety critical services. This is accomplished by
> > providing, by means
> > of separate (geostationary) signals of a set of corrections that
> > improve the
> > position and time calculation performed by the user satellite
> > receiver. EGNOS
> > provides these corrections not only for GPS but also for GLONASS.
>
> > So unless ESA (European Space Agency) has no idea what they're talking
> > about, EGNOS does provide corrections for GLONASS, besides taking
> > advantage of GLONASS satellites to better sample the ionosphere.
>
> How does it transmit them? *Does EGNOS broadcast on a frequency and
> modulation that GLONASS can pickup?

That's an excellent question. I have been trying to find something
like this:
www.nstb.tc.faa.gov/incoming/Waas_SV_Status.txt
for EGNOS, to no avail. That page gives the WAAS GPS clock and
ephemeris corrections in a very easy to read format.

There are pages that show VPL and HPL instantaneous, predicted and
past levels, without specifying if those levels are achieved with just
GPS or GPS+GLONASS.

Looking at the basic messages EGNOS defines, there is nothing GLONASS
specific, so the only possible way is each GLONASS SV has a distinct
ID (PRN) from GPS, and same broadcast format is used, with EGNOS
providing data for more PRNs (GPS + GLONASS). I'm not versed in
GLONASS details, but it looks like corrections for GPS/GLONASS/Galileo
can all be provided in the same format, fast/slow clock corrections,
clock change velocity, slow x/y/z ephemeris corrections, UDRE level,
and associated timestamps (validity window of each correction)

That's just an educated guess, but I really can't see a reason why it
doesn't work that way.

> > If that 2-3 meter uncertainty is 80% RMS, than its inline with actual
> > WAAS+GPS performance (GLONASS isn't making it worse). Looks very good
> > to me.
>
> What 2-3 meter uncertainty?

My bad, you said 3-4 meter. I wrote from memory and messed up the
figures. That's a little high for WAAS performance, depending on how
far you are from the nearest reference station.

> > With an abundance of satellites in view, the unit should be able to
> > weigh satellites that match each other and exclude/de weight the
> > others, regardless if they're GPS or GLONASS. The interesting question
> > is does it bother to do it. A RAIM algorithm of sorts.
>
> Would be nice. *Garmin are mum on how they mix the data.

Aren't all corporations mum on their internals. Always afraid of
giving something novel to the competition and/or showing their
customers some weakness.

> > The other very interesting test is to drive in downtown areas with
> > tall buildings all around and see if the unit can keep 5+ birds in
> > view at all time, that's the major value of GPS+GLONASS for a non
> > safety of life/not high accuracy unit.
>
> Keeping birds "in view" in urban canyons may be more a measure of
> failure than success. *Recent GPS receivers, esp. for hiking, have
> become very sensitive in order to get better performance in the woods.
> This also increases susceptibility to multipath.

True.

On 2011-11-23 17:31 , macpacheco wrote:
> On Nov 23, 7:08 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> wrote:
>>> Excerpt:
>>> 1.
>>> How does an SBAS (Satellite Based Augmentation System) system work?
>>> SBAS systems improve the performances of GPS with the objective to
>>> make it
>>> useable for safety critical services. This is accomplished by
>>> providing, by means
>>> of separate (geostationary) signals of a set of corrections that
>>> improve the
>>> position and time calculation performed by the user satellite
>>> receiver. EGNOS
>>> provides these corrections not only for GPS but also for GLONASS.
>>
>>> So unless ESA (European Space Agency) has no idea what they're talking
>>> about, EGNOS does provide corrections for GLONASS, besides taking
>>> advantage of GLONASS satellites to better sample the ionosphere.
>>
>> How does it transmit them? Does EGNOS broadcast on a frequency and
>> modulation that GLONASS can pickup?
>
> That's an excellent question. I have been trying to find something
> like this:
> www.nstb.tc.faa.gov/incoming/Waas_SV_Status.txt
> for EGNOS, to no avail. That page gives the WAAS GPS clock and
> ephemeris corrections in a very easy to read format.
>
> There are pages that show VPL and HPL instantaneous, predicted and
> past levels, without specifying if those levels are achieved with just
> GPS or GPS+GLONASS.
>
> Looking at the basic messages EGNOS defines, there is nothing GLONASS
> specific, so the only possible way is each GLONASS SV has a distinct
> ID (PRN) from GPS, and same broadcast format is used, with EGNOS
> providing data for more PRNs (GPS + GLONASS). I'm not versed in
> GLONASS details, but it looks like corrections for GPS/GLONASS/Galileo
> can all be provided in the same format, fast/slow clock corrections,
> clock change velocity, slow x/y/z ephemeris corrections, UDRE level,
> and associated timestamps (validity window of each correction)

Except that WAAS and EGNOS broadcast L1 with a 5X faster bit rate.
GLONASS is on a different frequency. So for GLONASS to get the data it
would need its own transponders in space, or a link from a GPS receiver.

I surmise that EGNOS measurements of GLONASS are simply to get more
samples of ionospheric effects that can be applied to GPS propagation
(with appropriate compensation for frequency if needed).

>
> That's just an educated guess, but I really can't see a reason why it
> doesn't work that way.
>
>>> If that 2-3 meter uncertainty is 80% RMS, than its inline with actual
>>> WAAS+GPS performance (GLONASS isn't making it worse). Looks very good
>>> to me.
>>
>> What 2-3 meter uncertainty?
>
> My bad, you said 3-4 meter. I wrote from memory and messed up the
> figures. That's a little high for WAAS performance, depending on how
> far you are from the nearest reference station.

WAAS performance figures are based on airborne receivers with
essentially no masking.

I haven't been out to an open area with the receiver yet. Maybe
tomorrow or Saturday.

Lastly, it's a figure calculated by the receiver. I take those as
best-case (not actual) indications and only trust measurements v. a truth.

>>> With an abundance of satellites in view, the unit should be able to
>>> weigh satellites that match each other and exclude/de weight the
>>> others, regardless if they're GPS or GLONASS. The interesting question
>>> is does it bother to do it. A RAIM algorithm of sorts.
>>
>> Would be nice. Garmin are mum on how they mix the data.
>
> Aren't all corporations mum on their internals. Always afraid of
> giving something novel to the competition and/or showing their
> customers some weakness.

They used to be more open. I recall using an early 6 channel receiver
from Trimble that allowed the sampling of a good number of the
internals. I keep meaning to buy a cheap test kit for Trimble - esp. as
I have a lot of software written for them. (Also hard coded for RS-232
- not sure how I'd get around that on a Mac with no RS-232 ports...).

>>> The other very interesting test is to drive in downtown areas with
>>> tall buildings all around and see if the unit can keep 5+ birds in
>>> view at all time, that's the major value of GPS+GLONASS for a non
>>> safety of life/not high accuracy unit.
>>
>> Keeping birds "in view" in urban canyons may be more a measure of
>> failure than success. Recent GPS receivers, esp. for hiking, have
>> become very sensitive in order to get better performance in the woods.
>> This also increases susceptibility to multipath.
>
> True.


--
"I see!" said the blind man as he picked up his hammer and saw.