[FOSS-GPS] RTKLIB Vehicle Accuracy

Tue Jul 1 13:35:24 PDT 2014

There is quite a difference between 10cm and 23m... I've used RG174 and
RG316 up to 3m without any noticeable difference on a Leica AT502 compared
to my LMR400 cable assembly.
Of course 23m of RG58.... we're talking about 15 dB cable loss here...
For short distances, there is really no need for such costly and rigid
cables like LMR400.

Regards,

Colin.
On Jul 1, 2014 10:17 PM, "Anton Strydom" <agstrydom at gmail.com> 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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