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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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  #11  
Old September 9th 14, 01:39 PM posted to sci.geo.satellite-nav
Alan Browne
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Default Capabilities of GPS chips in popular smartphones

On 2014.09.09, 02:31 , Hans-Georg Michna wrote:
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?


This changes receiver to receiver. They either show the correct PRN or
the unbiased NMEA number (difference of 87).

eg: 33 (NMEA) corresponds to PRN 120.

When the receiver sees PRN 120 it will output that number in data
streams unless it is an NMEA data stream. In that case, it subtracts 87
from the number.

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?


See the post I put up earlier with a link to SBAS signal coverage. The
PRN's are there.


--
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  #12  
Old September 10th 14, 02:16 PM posted to sci.geo.satellite-nav
Hans-Georg Michna
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Default Capabilities of GPS chips in popular smartphones

On Tue, 09 Sep 2014 08:39:51 -0400, Alan Browne wrote:

On 2014.09.09, 02:31 , Hans-Georg Michna wrote:


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?


This changes receiver to receiver. They either show the correct PRN or
the unbiased NMEA number (difference of 87).

eg: 33 (NMEA) corresponds to PRN 120.

When the receiver sees PRN 120 it will output that number in data
streams unless it is an NMEA data stream. In that case, it subtracts 87
from the number.


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?


See the post I put up earlier with a link to SBAS signal coverage. The
PRN's are there.


Ah, thanks! I will check for these on my GPS receivers.

Hans-Georg
  #13  
Old September 10th 14, 02:16 PM posted to sci.geo.satellite-nav
Hans-Georg Michna
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Default Capabilities of GPS chips in popular smartphones

On Tue, 09 Sep 2014 08:31:43 -0400, Alan Browne wrote:

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 thought the WAAS data transmitted by the WAAS satellites is
always the same, so a receiver would use just any one of them
and be happy with it.

Hans-Georg
  #14  
Old September 10th 14, 10:04 PM posted to sci.geo.satellite-nav
[email protected]
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Default Capabilities of GPS chips in popular smartphones

On my Samsung Note 3 in the "AndroiTS GPS Test" app, I see GPS and
Glonass but no WAAS. The author is unsure how to tell the phone to
send WAAS data. Possibly it is not capable.

He computes a Maidenhead location to 12 digits which goes a little off
in the smaller numbers compared to my 12 digit calculation. 12 digits
takes you down to 15 to 20 feet of position accuracy.

Thanks for a good discussion on this topic. I did not realize from a
lot of reading that EGNOS only presents European corrections. That
makes sense and is really the only logical way to do it, but I have
not gotten that from other sources.

The most sats I have ever seen (not tracked, just seen) is 26. If I
was getting the other two WAAS sats on that one receiver, it would be
28. For some reason it presents one but does not track it and does
not present the other 2 that I am capable of receiving and tracking.

I working with Canmore (Taiwan) to get their GT-321R to do GPS, WAAS
and Glonass. Right now, they ignore WAAS. They also have a bug where
they occasionally present the same PRN more than once in a single set
of GSV statements. (So far only for Glonass PRNs) They has the same
Az/El but different signal strength. Actually it is null in one and
present in the other. They think they can fix the lack of WAAS. Still
waiting on a patch. Would like to see it and switch to DGPS mode.

Still trying to get them to acknowledge the duplicate PRN problem. I
have sent them data but they are ignoring it for now. Otherwise a
good and sensitive receiver for a small price.

Mike

On Sun, 07 Sep 2014 12:22:46 +0200, Hans-Georg Michna
wrote:

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

  #16  
Old September 11th 14, 12:49 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 2014.09.10, 09:16 , Hans-Georg Michna wrote:
On Tue, 09 Sep 2014 08:31:43 -0400, Alan Browne wrote:

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 thought the WAAS data transmitted by the WAAS satellites is
always the same, so a receiver would use just any one of them
and be happy with it.


A likely thing. Just don't know. (And I know an engineer who wrote the
WAAS code for an aviation receiver, I guess I could track him down and ask.)


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


  #17  
Old October 15th 14, 03:05 AM posted to sci.geo.satellite-nav
Fluximous Fernansit Smith
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Posts: 3
Default Capabilities of GPS chips in popular smartphones

OK, to be clear enough that even you can understand.

WAAS sats are 3 SVs sitting over the equator.

They emit standard GPS signals and Differential corrections good for
the Americas.

I cannot see these 3 SVs on my phone. NOT AT ALL. THEY DO NOT
APPEAR.

Got it?

Was that so hard to understand?

FFS

On Thu, 11 Sep 2014 08:43:21 +0200, Hans-Georg Michna
wrote:

On Wed, 10 Sep 2014 14:04:32 -0700, wrote:

On my Samsung Note 3 in the "AndroiTS GPS Test" app, I see GPS and
Glonass but no WAAS. The author is unsure how to tell the phone to
send WAAS data. Possibly it is not capable.


These statements are too fuzzy to be of any value, because the
WAAS satellites double as GPS satellites. When you mention the
use of WAAS satellites, you should always specify whether you
mean the use of WAAS satellites as additional GPS satellites,
i.e. the reception of GPS data, or whether you mean the
reception of WAAS correction data. These are two entirely
different things.

Hans-Georg

  #18  
Old October 15th 14, 04:19 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 2014.10.14, 22:05 , Fluximous Fernansit Smith wrote:
OK, to be clear enough that even you can understand.

WAAS sats are 3 SVs sitting over the equator.

They emit standard GPS signals and Differential corrections good for
the Americas.

I cannot see these 3 SVs on my phone. NOT AT ALL. THEY DO NOT
APPEAR.

Got it?

Was that so hard to understand?


Just because you can't see them in the phone GPS app(s) doesn't mean
they are not being used by the nav function on the device. If the
receiver chip is not sending the data to the app, or the app writer
doesn't know how to command the data over, or if the OS (like in the
iPhone) obfuscates the data, then it won't be shown. That doesn't mean
it isn't being used in the nav solution.

Don't top post.

--
Among Broad Outlines, conception is far more pleasurable
than “carrying [the children] to fruition.”
Sadly, “there’s a high infant mortality rate among
Broad Outlines—they often fall prey to Nonstarters.”
"Bestiary of Intelligence Writing" - CIA

 




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