[FOSS-GPS] RTKLIB Vehicle Accuracy

Tue Jul 1 15:10:06 PDT 2014

I attached a png to the email and linked the antenna I have tried in my setup.

The cable I said was half a meter was RG-174 with that hole mount
antenna, no added ground plane. I have another antenna on a roof, with
a fairly long cable run, maybe ten to fifteen meters, but I don't
actually know what cable that is. I might need to figure that out.

But some tests was as mentioned performed with two recievers with the
hole mount antennas.

Nick

2014-07-01 22:46 GMT+02:00 David Kelley <DavidKelley at itsware.net>:
>
> where we used 23 meters of RG58,
>
> RG58 would be ill advised here (too much loss at L band)
> We use RG174 for moderately long runs and for temporary runs where vehicle
> can damage the coax.
> It is thin and it is tough.
>
> You can get a 500 foot spool from L-com and others for a modest price if
> crimping SMA connectors would not be a problem.
>
> If you are putting up a reference station and can use the larger diameter
> cable (which has less loss - a must for longer runs) then RG213 is to be
> preferred.
>
> I am amazed to see reports that these small patch antennas allow obtaining
> fixed results.  In the absence of a good ground plane I have had poor
> results, and even when it worked needed to try and calibrate out the phase
> angle biases.  [I work in an automotive environment where we typically use a
> more costly antenna simply because we do not want that as a factor]
>
> Nick, is the link you provided below good?, seem to go to a page with a
> small patch ant not plot results.
>
>
> Regards
> David Kelley
>
>
>
> On 7/1/2014 1:16 PM, Anton Strydom wrote:
>
> Hi Nick
>
> No for the base I use the Leica GG02 L1/L2 and only use the LEA6 T on the
> roving units
> I will save a plot and send it to you to show you the results I get.
>
> What coax to you use? I normally use either LMR 400 where I can use TNC
> connectors and 173 where I use SMA but then not longer than 10 cm of 173.
>
> I have had a situation where have a Leica SR 500 base and a AT504 antenna
> where we used 23 meters of RG58, we had lots of problems with the base. I
> changed the coax to LMR 400 and did not have any problems after the change
>
> Regards
>
> Anton
>
>
> On Tue, Jul 1, 2014 at 10:07 PM, Nick Østergaard <oe.nick at gmail.com> wrote:
>
> Ok, interresting. Is is working with the patch on both rover and base?
> I have tried with a setup, but I had had very bad results, especially
> when I moved. Attached is results I have had, and that with antennas
> as [1] with bias voltage on and half a meter of coax. The signal is
> great as far as I remember. I have LEA6T's also (maybe 4T), although I
> don't quite remember exactly, it is quite some time ago since I tried.
>
> Attached is a post processed result.
>
> [1]
> http://dk.rs-online.com/web/p/smt-antenner/7239151/?searchTerm=SM-1575&relevancy-data=636F3D3226696E3D4931384E4B6E6F776E41734D504E266C753D6461266D6D3D6D61746368616C6C7061727469616C26706D3D5E5B5C707B4C7D5C707B4E647D2D2C2F255C2E5D2B2426706F3D313326736E3D592673743D4D414E5F504152545F4E554D4245522677633D424F5448267573743D534D2D3135373526
>
> 2014-07-01 21:38 GMT+02:00 Anton Strydom <agstrydom at gmail.com>:
>
> Hi Nick
>
> Yes I get a reasonable plot using that specific unit. However for what we
> intend doing in the long term we will be using a different design helical
> antenna that we are in the process of developing.
>
> The units in the photographs are only for testing and setting up but we
>
> get
>
> good results. For communication we use cellular routers connected to
>
> Leica
>
> GGO2 L1/L2 base or else we use 3D Robotics XBEE radios. On the roving
>
> unit I
>
> use an ARM processor where I have 4 rs232 ports available. It works very
> well and is very stable.
>
> The radios I use where i have no cellular coverage.
>
> Attached is a photograph of  the base setup
>
> Regards
>
> Anton
>
>
> On Tue, Jul 1, 2014 at 9:27 PM, Nick Østergaard <oe.nick at gmail.com>
>
> wrote:
>
> Hi Anton
>
> Really? You get by with that small patch antenna? Is that a good (green
>
> in
>
> rtkplot) RTK solution you get from that constant?
>
> Regards
> Another Nick
>
> Den 01/07/2014 21.11 skrev "Anton Strydom" <agstrydom at gmail.com>:
>
> Hi Nick
>
> I have done a lot of testing with U-Blox LEA 6T at speeds of up to 120
>
> km
>
> / h. Lat & Lon does not appear to be a problem but elevation is a
>
> problem. I
>
> paid the equivalent of $60 for the 2 receivers and ceramic patch
>
> antennas.
>
> They are accurate on base line up to 10km where after accuracy
> drastically degrades.
>
> I do all my testing in real time and do not post process.
>
> If you want to I can speak to my supplier and see if they still have
>
> some
>
> of the LEA 6T's in stock at the price I paid for them.
>
> Attached are photographs of the units I am using
>
> Regards
>
> Anton
>
>
> On Tue, Jul 1, 2014 at 8:50 PM, Danny Miller <dannym at austin.rr.com>
> wrote:
>
> It does work in moving.  But signal problems do still make the
>
> position
>
> jump around, trees and buildings and an antenna's orientation
>
> changing can
>
> make an error happen.  Antenna quality has a lot to do with that, too.
>
> RTKLib requires a GPS with RAW pseudorange outputs.  The NV08C is a
> good, cheap one to do it:
>
> http://www.nvs-gnss.com/contacts.html
>
> Contact your local sales rep there- it was actually easy in my
> experience to order a couple from them, and oddly cheaper than Newark
> element 14, as well as quicker to ship.
>
> Danny
>
>
> On 7/1/2014 1:24 PM, Nick wrote:
>
> Hello,
>
> I am interested in getting an RTK GPS setup working for a moving
> vehicle, not fast, perhaps 10 mph. I would postprocess the data
>
> collected
>
> later, using data downloaded from a nearby station.
>
> My desire is to log elevation data every few seconds as the vehicle
> drives. I hope to achieve 10-20 cm accuracy for the position and the
> elevation.
>
> As I research RTKLIB, it seems like most information I come across is
> regarding a static location. Is my goal feasible to achieve this kind
>
> of
>
> accuracy as the vehicle moves?
>
> If so, can anyone recommend a good board to get me started? I'm hoping
> to be able to do this for under $200 (just one receiver since the base
> station is public) -- please give me a reality check if this is
>
> unlikely.
>
> Thanks,
>
> Nick
>
>
>
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> --
> Regards,
> David Kelley
> ITS Programs Manager
> SubCarrier Systems Corp. (SCSC)
> 1833 East Foothill Blvd. Glendora, CA USA  91741
> 626-485-7528 (Cell)      888-950-8747 (Main)
> 626-513-7715 (Office)    888-613-0757 (Fax)
> <DavidKelley at ITSware.net>
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