[teqc] Converting Android GPS data to Rinex file format

Lalitha myracacc at gmail.com
Wed Oct 13 12:01:52 MDT 2010


Thanks Jim for the clear reply. Finally one more question.
Is there any other methods to achieve post processing dgps corrections other
than converting to Rinex format.
I understand from all of your replies that the underlying raw gps data is
must for doing corrections with the base station gps data.
But still, want to give a try asking if there is any other ways to do it.

Thanks,
Lalitha.

On Wed, Oct 13, 2010 at 10:44 AM, James Johnson <jjohnson at ucar.edu> wrote:

> Hi Lalitha,
>
> It is not possible to generate RINEX from an android phone.  This is
> because the raw data required for RINEX is not exposed by the Android API.
>  You can get some information about the SVs tracked and a position, but you
> can not get the raw Pseudo range data.  The NMEA strings are not useful for
> generating RINEX as well, simply because the data is not there.
>
> Sorry for the sad news.
>
> Best Regards,
> Jim Johnson
> On Oct 13, 2010, at 11:40 AM, Lalitha wrote:
>
> > Hi Homan,
> >
> > Tons of thanks for the detailed reply. I've been searching the net and
> posting in all the android, gps forums for the past 10 days and didn't get
> any response till now. Thanks to teqc mailing list.
> >
> > Q1. I checked the android api for the gps data. It provides GPS Satellite
> info from which we can get elevation, PRN (pseudo-random number), snr,
> Almanac, ephemeris data etc.
> >      Ref :
> http://developer.android.com/reference/android/location/GpsStatus.html
> > With these data, will it be possible to generate Rinex file directly from
> android app?.
> >
> > Q2. Also, there is a nmealistener provided in the android api using which
> we can capture gps nmea strings. Will this data be useful by anyway to
> translate to rinex format? (Though, I coudnt succeed capturing nmea string
> using my htc magic phone, I can try with some other phones if this data will
> be  useful for post processing).
> >
> > Thanks,
> > Lalitha.
> >
> > On Wed, Oct 13, 2010 at 9:58 AM, Homan, Thomas <thoman at co.gila.az.us>
> wrote:
> > Lalitha,
> >
> >
> > .gpx files cannot be converted to Rinex as they don’t contain the
> necessary data elements. If I remember correctly, the api only outputs the
> final latitude and longitude values. I don’t believe the underlying raw gps
> data is accessible but I’m just getting started on Exclipse.
> >
> >
> > To generate a Rinex file you need to have access to underlying
> information such as pseudorange, carrier phase and other data from each
> satellite in the GPS constellation. As an example, below are a .gpx file
> compared to a Rinex file that I collected in 2005. Each of the 7 satellites
> visible has a set of 7 data elements logged out of my $$$ survey grade
> receiver and this happens each logging period.
> >
> >
> > Peruse the api docs and see if there is access to the underlying data and
> not the final coordinates. If not, then you might be out of luck. One thing
> you might explore is if the android OS supports inserting DGPS correctors so
> you could get real time sub-meter accuracies.
> >
> >
> > Hope this helps some.
> >
> >
> > Tom
> >
> >
> > GPX
> >
> > <?xml version="1.0" encoding="ISO-8859-1"?>
> >
> > <gpx xmlns="http://www.topografix.com/GPX/1/1" xmlns:xsi="
> http://www.w3.org/2001/XMLSchema-instance" version="1.1" creator="Doug
> Forster's map viewer" xsi:schemaLocation="
> http://www.topografix.com/GPX/1/1
> http://www.topografix.com/GPX/1/1/gpx.xsd">
> >
> > <wpt lat="-42.48781" lon="172.29404">
> >
> > <ele>1273</ele>
> >
> > <name>NwDvls</name>
> >
> > <cmt> 30/01/10 19:14</cmt>
> >
> > <desc>New Devils Den Biv</desc>
> >
> > <sym>Anchor</sym>
> >
> > <extensions>
> >
> > <type xmlns="Freshmap">Place</type>
> >
> > <TrackColor xmlns="Freshmap">0</TrackColor>
> >
> > <FontSize xmlns="Freshmap">90</FontSize>
> >
> > <GPSColor xmlns="Freshmap">14</GPSColor>
> >
> > <Layout xmlns="Freshmap">5</Layout>
> >
> > </extensions>
> >
> > </wpt>
> >
> > </gpx>
> >
> >
> > Rinex
> >
> > 05 10 12 14 44 45.0000000  0  7G 1G24G23G20G16G25G11
> >
> >   18540407.76711  14441990.35651  22140106.912    22140108.9425
> 22140103.6715
> >
> >      -1502.342       -1170.656
> >
> >   18405511.80411  14342294.04151  23619878.513    23619880.7005
> 23619875.3565
> >
> >        382.895         298.360
> >
> >   18279304.44211  14260112.94351  22317896.240    22317897.3485
> 22317888.9405
> >
> >       2122.449        1653.856
> >
> >   18331079.75811  14289623.90551  20672596.529    20672597.6675
> 20672590.3895
> >
> >       1386.704        1080.549
> >
> >   18282886.39611  14256935.72751  21779940.978    21779941.1535
> 21779934.4995
> >
> >       2177.108        1696.448
> >
> >   18595837.79911  14470056.42251  21824971.770    21824972.4395
> 21824966.6485
> >
> >      -2263.324       -1763.629
> >
> >   18612482.40511  14492926.57751  23828871.571    23828874.4325
> 23828869.0685
> >
> >      -2470.753       -1925.262
> >
> >
> > From: teqc-bounces at ls.unavco.org [mailto:teqc-bounces at ls.unavco.org] On
> Behalf Of Lalitha
> > Sent: Wednesday, October 13, 2010 9:03 AM
> > To: teqc at ls.unavco.org; gpstech at ls.unavco.org
> > Subject: [teqc] Converting Android GPS data to Rinex file format
> >
> >
> > Hi,
> >
> > How do i convert the gps data I get from Android GPS Receiver into Rinex
> file format in order to do Post processing corrections.
> > I can write the gps data into .gpx format using the android api provided.
> I use HTC Magic phone with 2.2 api version.
> > I cudnt find option for android in the teqc toolkit. Can anyone help how
> do I convert to Rinex?
> > Also I'm looking for the post processing softwares or service available
> for evaluation. I could find only one free evaluation software 'PPro2' from
> Kinematic GPS.
> > Is there any other free post processing software present?
> >
> > Thanks,
> > Lalitha.
> >
> >
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> >
> >
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