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 <[email protected]> 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 <[email protected]>:
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 <[email protected]>
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" <[email protected]>:
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 <[email protected]>
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)
<[email protected]>
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