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sci.geo.satellite-nav (Global Satellite Navigation) (sci.geo.satellite-nav) Discussion of global navigation satellite systems (GNSS). Topics include the technical aspects of GNSS operation, user experiences in the use of GNSS, information regarding GNSS products and discussion of GNSS policy (such as GPS selective availability).

Capabilities of GPS chips in popular smartphones



 
 
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  #1  
Old September 7th 14, 10:22 AM posted to sci.geo.satellite-nav,alt.satellite.gps
Hans-Georg Michna
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Posts: 764
Default Capabilities of GPS chips in popular smartphones

I just posted the following to the OnePlus One discussion forum
at:
https://forums.oneplus.net/threads/g.../#post-5140926

----- Quote begins -----
I found most of the satellite numbers.

1 to 32 are GPS satellites (US). 64 to 96 is Glonass (Russia).
201 to 205 (?) are the geostationary or geosynchronous (tracing
a north-south-oriented figure of 8 above China) Beidou
satellites. You will always see these roughly where China is,
i.e. above the eastern horizon from Europe. 206 (?) and above
are the already flying and the planned Beidou satellites in MEO
(Medium Earth Orbit, i.e. circling the earth and completing one
orbit in 10 to 14 hours, like the GPS, Glonass, and Galileo
satellites).

The GPS Status app shows the GPS satellites as circles, all
others as squares.

I believe, but am not sure, that our phone does not receive QZSS
(the Japanese system of geostationary and geosynchronous
satellites) and also not Galileo, and I am still lacking
information about which of the various SBAS systems (see
http://en.wikipedia.org/wiki/GNSS_augmentation ) are used.
Certainly WAAS (covering the US) is used, but I could not find
out for sure whether EGNOS (covering Europe) is used (almost
certainly it is), and whether MSAS (Japan), Gagan (India) or any
of the planned systems are or will be used. Any information is
welcome.

Note that most or all SBAS satellites are geostationary, and
many or all double as positioning satellites (GPS, EGNOS, etc.).
Note also that a smartphone could obtain the enhancement data
over the Internet and would not necessarily have to receive them
from the satellites, although it should be able to receive the
satellites in the case that it has no Internet connection. I am
pretty sure that most smartphones can and do use the alternative
Internet data. If you see satellites with numbers from 100 to
199, these could be SBAS satellites, possibly WAAS or EGNOS. If
they stay in the same place for hours, then they are
geostationary. More information is welcome here also.
----- Quote ends -----

As you can see, there are quite a few open questions regarding
the capabilities of various smartphone GPS chips, in the case of
the OnePlus One this:

Qualcomm WTR1625L chipset, supports all networks (including
TD-SCDMA + TD-LTE networks), and integrated GPS/GLONASS/COMPASS
(Beidou) satellite navigation system.

Some of the open questions a

* Can it really not receive QZSS?

* Does it use EGNOS? (probably yes)

* What, if any, are the displayed satellite numbers for the WAAS
and EGNOS satellites in the GPS Status app?

* Does the chip have capabilities that are currently dormant,
but could be enabled through firmware updates? Galileo and QZSS
come to mind, as well as present and future SBAS (MSAS etc.).

I'm also interested in the capabilities of other GPS chips that
are used in other popular smartphones. For example, the chip
used in new Samsung tablets (what's its name?) seems to be able
to receive GPS and Glonass only, not Beidou.

Followup-to: sci.geo.satellite-nav
  #2  
Old September 7th 14, 11:08 AM posted to sci.geo.satellite-nav
SoundMute
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Posts: 3
Default Capabilities of GPS chips in popular smartphones

On 7.9.2014. 12:22, Hans-Georg Michna wrote:
Certainly WAAS (covering the US) is used, but I could not find
out for sure whether EGNOS (covering Europe) is used (almost
certainly it is), and whether MSAS (Japan), Gagan (India) or any
of the planned systems are or will be used. Any information is
welcome.


It depends where are you situated. In North America the GPS chip uses
WAAS. In Europe EGNOS (not WAAS) and so on.

All this Augmentation Services in one word are called SBAS (Satellite
Based Augmentation Systems). But due to technical constraints/position,
GPS can receive only one of those at the time, the one that has been
broadcasted above the certain Territory.

However, they are all similar and have the same function, to
Augment/improve/correct the precision of raw data. It is actually called
D(Differential)GPS. Differential corrections are very easy to
understand. It is a difference between raw (unprecise) data and
corrected data. That is why the corrections are called differential.

The SBAS sats are Geostationary, at fixed position usually above
Equator. They rely on a number of Ground Reference stations and they
take corrective signals, average them and broadcast into one burst to
anything that listens and has the capability to decode the signal. That
is you GPS firmware actually.

All of this is happening in real-time without user intervention.

Hope it helps.
  #3  
Old September 7th 14, 02:01 PM posted to sci.geo.satellite-nav
Alan Browne
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Posts: 1,339
Default Capabilities of GPS chips in popular smartphones

On 2014.09.07, 07:08 , SoundMute wrote:
On 7.9.2014. 12:22, Hans-Georg Michna wrote:
Certainly WAAS (covering the US) is used, but I could not find
out for sure whether EGNOS (covering Europe) is used (almost
certainly it is), and whether MSAS (Japan), Gagan (India) or any
of the planned systems are or will be used. Any information is
welcome.


It depends where are you situated. In North America the GPS chip uses
WAAS. In Europe EGNOS (not WAAS) and so on.

All this Augmentation Services in one word are called SBAS (Satellite
Based Augmentation Systems). But due to technical constraints/position,
GPS can receive only one of those at the time, the one that has been
broadcasted above the certain Territory.


My (pretty old) GPS recorder logs 2 WAAS and up to one EGNOS at the same
time from Montreal. My Garmin receiver (that I sold) would show WAAS
and EGNOS sats at the same time. How each receiver processed and/or
prioritized each is not known to me.


--
I was born a 1%er - I'm just more equal than the rest.


  #4  
Old September 7th 14, 03:13 PM posted to sci.geo.satellite-nav
SoundMute
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Posts: 3
Default Capabilities of GPS chips in popular smartphones

On 7.9.2014. 16:01, Alan Browne wrote:
My (pretty old) GPS recorder logs 2 WAAS and up to one EGNOS at the same
time from Montreal. My Garmin receiver (that I sold) would show WAAS
and EGNOS sats at the same time. How each receiver processed and/or
prioritized each is not known to me.


Please see the SBAS coverage at:
http://www.egnos-portal.eu/discover-...gnos/what-sbas

I really do not know how anybody can use both systems at the same time
as they do not even overlap. It is however up to the manufacturer to
label them as he sees fit.

The same receiver will use WAAS in North America and EGNOS in Europe.
That is a fact. But not in the same time. Can you be in America and
Europe at the same time?
  #5  
Old September 7th 14, 10:21 PM posted to sci.geo.satellite-nav
Alan Browne
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Posts: 1,339
Default Capabilities of GPS chips in popular smartphones

On 2014.09.07, 11:13 , SoundMute wrote:
On 7.9.2014. 16:01, Alan Browne wrote:
My (pretty old) GPS recorder logs 2 WAAS and up to one EGNOS at the same
time from Montreal. My Garmin receiver (that I sold) would show WAAS
and EGNOS sats at the same time. How each receiver processed and/or
prioritized each is not known to me.


Please see the SBAS coverage at:
http://www.egnos-portal.eu/discover-...gnos/what-sbas

I really do not know how anybody can use both systems at the same time
as they do not even overlap. It is however up to the manufacturer to
label them as he sees fit.


Of course they overlap. And greatly:

http://sxbluegps.com/wp-content/uplo...2/carte1_s.gif

PRN 120 (EGNOS) overlaps PRN 133 and 138 (WAAS) by a good margin.


The same receiver will use WAAS in North America and EGNOS in Europe.
That is a fact. But not in the same time. Can you be in America and
Europe at the same time?


I guess geometry is not your strong suit.

From Montreal a GPS receiver picks up 2 and sometimes 3 WAAS sats and
at least one EGNOS sat at the same time given a clear view of the sky.

--
I was born a 1%er - I'm just more equal than the rest.


  #6  
Old September 8th 14, 07:01 AM posted to sci.geo.satellite-nav
Terje Mathisen[_3_]
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Posts: 26
Default Capabilities of GPS chips in popular smartphones

Alan Browne wrote:
On 2014.09.07, 11:13 , SoundMute wrote:
On 7.9.2014. 16:01, Alan Browne wrote:
My (pretty old) GPS recorder logs 2 WAAS and up to one EGNOS at the same
time from Montreal. My Garmin receiver (that I sold) would show WAAS
and EGNOS sats at the same time. How each receiver processed and/or
prioritized each is not known to me.


Please see the SBAS coverage at:
http://www.egnos-portal.eu/discover-...gnos/what-sbas

I really do not know how anybody can use both systems at the same time
as they do not even overlap. It is however up to the manufacturer to
label them as he sees fit.


Of course they overlap. And greatly:

http://sxbluegps.com/wp-content/uplo...2/carte1_s.gif

PRN 120 (EGNOS) overlaps PRN 133 and 138 (WAAS) by a good margin.


Right. :-)

The further north you are, the more you'll see sats from the "opposite"
side of the world.

Here in Oslo I recently had 26 sats on my S5, I noticed 205, 206, 209,
210 & 211, of which 2 or 3 were being used at the time.


The same receiver will use WAAS in North America and EGNOS in Europe.
That is a fact. But not in the same time. Can you be in America and
Europe at the same time?


I guess geometry is not your strong suit.

From Montreal a GPS receiver picks up 2 and sometimes 3 WAAS sats and
at least one EGNOS sat at the same time given a clear view of the sky.


The thing about WAAS/EGNOS is that it really doesn't matter if you can
pick up a WAAS sat in Europe or EGNOS in the US: The augmentation data
sent by an EGNOS sat contains correction data in the form of a 2D model
covering Europe, not the US!

This means that except for any possible sat clock correction data
(likely to be extremely small), the EGNOS differential data simply
doesn't apply to a receiver in the US.

Terje

--
- Terje.Mathisen at tmsw.no
"almost all programming can be viewed as an exercise in caching"
  #7  
Old September 8th 14, 11:12 AM posted to sci.geo.satellite-nav
SoundMute
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Posts: 3
Default Capabilities of GPS chips in popular smartphones

On 8.9.2014. 0:21, Alan Browne wrote:
I really do not know how anybody can use both systems at the same time
as they do not even overlap. It is however up to the manufacturer to
label them as he sees fit.


Of course they overlap. And greatly:


Strange that you picked the picture from Geneq. It concerns only the
SXBlue Receivers which are somewhat special. They use SBAS to a full
potential, and SBAS (+COAST) only. No need for local Base stations or
Post-processing. In my opinion the SXBlue are one of the best
professional GNSS receivers in the world, for the time being. Also, they
have a unique capability of additional extrapolation of ionospheric
Maps, extending the SBAS coverage (by algorithms) which, only marginally
helps some countries.

PRN 120 (EGNOS) overlaps PRN 133 and 138 (WAAS) by a good margin.


This is not the point. The geostationary satellites may cover the whole
world, even the Southern Hemisphere. But they do not broadcast SBAS
ranging for the Southern Hemisphere for example. It does not matter if
their potential (theoretical) coverage is big.

The point is the Reference station/s on the ground. They perform the
differential corrections. PRN satellites just re-broadcast the
corrections to the GNSS receivers.

Even if you do receive an EGNOS corrected value in Montreal, if taken
into account, it can only worsen the precision of you GPS receiver,
because the Reference station the corrections originated from is
thousands of miles away from you. It does not apply.

I guess geometry is not your strong suit.


I do not know what you mean by this. The geometry of PRNs (Inmarsat and
the like) is not an issue. It is always fixed. These sats do not move
over the ground. They follow the rotation of Earth, and are always at
the same position above the Earth (relatively speaking).

The geometry of GPS satellites is a totally different matter. They orbit
the planet and make one full circle every 12 hours. They come and go
(replaced by another SV (Satellite Vehicle) every few hours or so).

That is why you do not see the same set of sats at the same time over
USA and Europe. And that is why the EGNOS corrections (even if you see
them) is of no relevance to N. American Continent, and vice-versa. What
is the use of having a corrected position for the set of sats over
Europe when you do not see them over Montreal. The corrections do not
apply to the SV that you see at your position.

From Montreal a GPS receiver picks up 2 and sometimes 3 WAAS sats and at least one EGNOS sat at the same time given a clear view of the sky.


I do not doubt your words but find it hard to believe. I may be wrong.
Besides, it is not necessary to see three WAAS sats for the differential
corrections. One is enough. Which one will your GPS receiver pick up
depends on your position. The most important thing is to correct the raw
readings of the SVs that you (your GPS Antenna) see and use.

And one more thing, just an observation. I frequently think about GPS
system as being "alive". The GPS satellites move, broadcast their
position once per second, the ground stations take care about
corrections, and your GPS receiver handles all the data and give you an
address (your position) in the wilderness. Isn't that amazing?

  #8  
Old September 9th 14, 06:31 AM posted to sci.geo.satellite-nav
Hans-Georg Michna
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Posts: 764
Default Capabilities of GPS chips in popular smartphones

Just by the way, the WAAS satellites double as GPS satellites,
i.e. in addition to the correction data they also transmit the
standard GPS signals. Does anybody know their numbers, ideally
the numbers displayed by the GPS Status app?

And does anybody know whether that is true for EGNOS as well,
i.e. do the EGNOS satellites also double as Galileo sats? And
does anybody know their numbers?

Hans-Georg
  #9  
Old September 9th 14, 12:31 PM posted to sci.geo.satellite-nav
Alan Browne
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Posts: 1,339
Default Capabilities of GPS chips in popular smartphones

On 2014.09.08, 03:01 , Terje Mathisen wrote:
Alan Browne wrote:
On 2014.09.07, 11:13 , SoundMute wrote:
On 7.9.2014. 16:01, Alan Browne wrote:
My (pretty old) GPS recorder logs 2 WAAS and up to one EGNOS at the
same
time from Montreal. My Garmin receiver (that I sold) would show WAAS
and EGNOS sats at the same time. How each receiver processed and/or
prioritized each is not known to me.

Please see the SBAS coverage at:
http://www.egnos-portal.eu/discover-...gnos/what-sbas

I really do not know how anybody can use both systems at the same time
as they do not even overlap. It is however up to the manufacturer to
label them as he sees fit.


Of course they overlap. And greatly:

http://sxbluegps.com/wp-content/uplo...2/carte1_s.gif

PRN 120 (EGNOS) overlaps PRN 133 and 138 (WAAS) by a good margin.


Right. :-)

The further north you are, the more you'll see sats from the "opposite"
side of the world.

Here in Oslo I recently had 26 sats on my S5, I noticed 205, 206, 209,
210 & 211, of which 2 or 3 were being used at the time.


The same receiver will use WAAS in North America and EGNOS in Europe.
That is a fact. But not in the same time. Can you be in America and
Europe at the same time?


I guess geometry is not your strong suit.

From Montreal a GPS receiver picks up 2 and sometimes 3 WAAS sats and
at least one EGNOS sat at the same time given a clear view of the sky.


The thing about WAAS/EGNOS is that it really doesn't matter if you can
pick up a WAAS sat in Europe or EGNOS in the US: The augmentation data
sent by an EGNOS sat contains correction data in the form of a 2D model
covering Europe, not the US!

This means that except for any possible sat clock correction data
(likely to be extremely small), the EGNOS differential data simply
doesn't apply to a receiver in the US.


The prior-prior point was really about whether the receiver, reading 2
or more WAAS would use data from only one or several - in the case of
the North American based receiver.

--
I was born a 1%er - I'm just more equal than the rest.


  #10  
Old September 9th 14, 12:32 PM posted to sci.geo.satellite-nav
Alan Browne
external usenet poster
 
Posts: 1,339
Default Capabilities of GPS chips in popular smartphones

On 2014.09.08, 07:12 , SoundMute wrote:
On 8.9.2014. 0:21, Alan Browne wrote:
I really do not know how anybody can use both systems at the same time
as they do not even overlap. It is however up to the manufacturer to
label them as he sees fit.


Of course they overlap. And greatly:


Strange that you picked the picture from Geneq. It concerns only the
SXBlue Receivers which are somewhat special.


I picked an image that shows SBAS coverage. Where the signal falls and
not the silly cartoon that you showed earlier.

--
I was born a 1%er - I'm just more equal than the rest.


 




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