[FOSS-GPS] FOSS-GPS Digest, Vol 102, Issue 2

[Dhirendra Singh]

which messages from the base raw binary data are redundant & not needed by
rover strictly  & hence need not be sent,
in other words which messages are  necessarily required from the base raw
binary data for quality RTK fix when the internet
speed is slow for transferring data through NTRIP ? How to do it in SNIP
while sending serial stream in raw binary data form from base ?

Regards,
Dhirendra singh,
INDIA

On Thu, Aug 24, 2017 at 12:30 AM, <foss-gps-request at lists.osgeo.org> wrote:

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> Today's Topics:
>
>    1. Re: Post Processing with RTKLIB (DavidKelley at ITSware.net)
>    2. Re: Post Processing with RTKLIB (RTKPostProcess)
>    3. Re: Post Processing with RTKLIB (DavidKelley at ITSware.net)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 22 Aug 2017 13:35:42 -0700 (MST)
> From: "DavidKelley at ITSware.net" <DavidKelley at ITSware.net>
> To: foss-gps at lists.osgeo.org
> Subject: Re: [FOSS-GPS] Post Processing with RTKLIB
> Message-ID: <1503434142706-7573585.post at n2.nabble.com>
> Content-Type: text/plain; charset=us-ascii
>
> Post processing raw observation data gathered in the field has been very
> common decades and you should have no problems using RTKLIB (the RTKPOST
> tool) for that.  Many "old timers" still do it that way for various reasons
> and when we are in the filed we are checking as we go but we old "trust"
> the
> post processed results.  And post processioning means you can also use
> final
> orbits and other data products that are readily available to get better
> results.  All of this is moot if your field data is itself corrupted.  And
> you can easily turn RTCM3.x into RINEX files with other RTKLIB tools and
> find 3rd party processing services to solve it for you.
>
> Time synchronization will not in fact be an issue.  RTCM 3.x provides the
> precise time over the current GPS week, so you have to tell the tool
> (RTKLIB
> or any other such tool) what week a file came from but the file name
> conventions used often help with that.  There are a few other messages and
> tricks, but this solves 99% of your issues.  The navigation filter will
> then
> determine the precise time.
>
> The data from the "nearest RTK" station of course depends on where you are.
> Many tools (RTKLIB, SNIP, and often the NTRIP Caster device itself) will
> provide a means to capture the raw RTCM data for your post processing
> needs.
> NGS CORS even runs a long term FTP site with such data, but the data is
> decimated.  Depending on your application that may not be an issue.
>
> *So yes this is quite possible and routinely done*. But you have not told
> the group anything more about the devices in the field (the rovers) and
> what
> span of location and how often the positional estimates are wanted, what
> precision is required, etc. Many of the practical details and useful advice
> you might get will turn on that.    Regards, DCK
>
>
>
> --
> View this message in context: http://open-source-gps-
> related-discussion-and-support.1099874.n2.nabble.com/
> Post-Processing-with-RTKLIB-tp7573584p7573585.html
> Sent from the Open Source GPS-related discussion and support mailing list
> archive at Nabble.com.
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 22 Aug 2017 23:42:35 -0700 (MST)
> From: RTKPostProcess <g.bado at ro-sys.hu>
> To: foss-gps at lists.osgeo.org
> Subject: Re: [FOSS-GPS] Post Processing with RTKLIB
> Message-ID: <1503470555485-7573586.post at n2.nabble.com>
> Content-Type: text/plain; charset=us-ascii
>
> Thank you for your answer,
> The device contains an NV08C-CSM GNSS module, with 2JM013-010/113-UFL
> antenna. The desired precision is 2cm, and we need them as often as
> possible, we want a really precise route from the FIX data.
> My problem with the synchronization is that we can capture both the rover
> and the base station data, but because we capture it in two different
> place,
> it maybe cause some problem when we want to process it. For example because
> of the slow internet connection or anything else the .tag file we create
> for
> this probably will have a few second delay.
>
> Best regards,
> Greg
>
>
>
> --
> View this message in context: http://open-source-gps-
> related-discussion-and-support.1099874.n2.nabble.com/
> Post-Processing-with-RTKLIB-tp7573584p7573586.html
> Sent from the Open Source GPS-related discussion and support mailing list
> archive at Nabble.com.
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 23 Aug 2017 03:19:02 -0700 (MST)
> From: "DavidKelley at ITSware.net" <DavidKelley at ITSware.net>
> To: foss-gps at lists.osgeo.org
> Subject: Re: [FOSS-GPS] Post Processing with RTKLIB
> Message-ID: <1503483542797-7573587.post at n2.nabble.com>
> Content-Type: text/plain; charset=us-ascii
>
> In this case you are planning to use low lost L1 only device with a ten
> dollar patch antenna.  Search for Michele Bavaro to find practical use tips
> on that chip and RTKLIB.  By now you probably know L1/L2 is to be
> preferred,
> and that you need to be <15km (better yet <10km) from your base stations to
> get fixes with this setup.  We have done RTK mobile <2cm work on vehicles
> with the NV08 and RTKLIB, but we tend to use better antenna (see
> https://www.use-snip.com/kb/knowledge-base/question-what-
> antenna-should-i-use/).
> You do not state your data rates, only "as often as possible" - to some
> people that means 1Hz, to others much more (that chip does 20hz with the
> normal increase in measurement noise floor). One presumes you have a
> generally clear sky? No forest cover? Is this a drone, a ground vehicle or
> a
> manpack or other? This directly effects the expectations of signal loss you
> will have.  You will end up with lots of data, in the NV08 propriety
> format,
> that you will then translate to RTCM3 or to RINEX for use in post. And
> RTKLIB does all that just fine.
>
> If you are processing "at the end of the day" then the slow internet should
> not matter here (see prior reply about time tags, I do not think you will
> need to use the tag option), but perhaps I do not understand your config.
> It
> is likely you will want to record the RTCM streams from all the base
> stations your device may be near and select which is best in post.  You
> have
> not mentioned what the span of rover operation would be.  BTW, a point I
> failed to note in my first post of that you need not send a precise / good
> position to the NTRIP Caster and you only need to send it once.  For most
> needs, a 1km will suit, so in fact the unaided fix from this device in
> NMEA-183 format will be fine (or you can add it by hand). The Caster will
> then pick the best station to send to you (and you will get the exact
> location for that data).
>
>
>
> --
> View this message in context: http://open-source-gps-
> related-discussion-and-support.1099874.n2.nabble.com/
> Post-Processing-with-RTKLIB-tp7573584p7573587.html
> Sent from the Open Source GPS-related discussion and support mailing list
> archive at Nabble.com.
>
>
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