[teqc] Converting Android GPS data to Rinex file format

Homan, Thomas thoman at co.gila.az.us
Wed Oct 13 10:58:11 MDT 2010


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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