[NLRS] GPS and RTK

[Chris Elmquist]

I agree with Donn that you probably need more information about which
brand, make, model of the RTK base station they wish to install.

I work in this field (pun intended) somewhat now and there are so many
ways of delivering the RTK correction data from the base station to the
users that I think it's too hard to guess about what they may be doing.

Many systems now use part 15 unlicensed stuff so this could be 900 MHz
or 2.4 GHz.  Some use WiFi. 

Some use cellular where the base station is actually a node on the
internet via a cellular modem and the vehicles establish data calls over
their own cellular modems into the cloud to get the correction data.
I work on these sorts of systems so don't blame me for the ones that
QRM the ham bands :-)

So, you really have to see who's gear is involved before you can know
more.  Each of the manufacturers have multiple types of systems too
so you need to know more than just "it's a Trimble" or "it's a Deere"
for example.

It would certainly be a reasonable question to ask, given that you need
to know what sort of transmitter might be operating on your tower.

The systems that claim 5 to 10 mile coverage and require line of sight
between the vehicle and the base station are probably the ones to watch
out for as they will be running some sort of VHF or UHF RF modem in the 5W
(+/-) range as Jerry suggested.

Chris N0JCF

On Thursday (06/12/2014 at 11:00PM -0500), Donn, WA2VOI wrote:
> 
> 
> Before making any decision, I suggest you need more information as
> to exactly which RTK systems they are planning on using.  Are they
> looking at using your tower to improve the range of an unlicensed
> (i.e., 869/900MHz, 1/0.5w transmitter) or a licensed 460MHz
> business-band system (20 W or more) ?  How much operating do you
> do/expect to do on 432MHz ?  432 EME ?  440 MHz FM ?  If a lot,
> maybe you should politely refuse.  (Especially for EME !)  On
> 902/903, again, you might need a bit more information.  Where in the
> band, exactly, is the TX operating.  Far enough away that a filter
> will solve the possible overload problem.
> 
> Also, what is the time usage of the system ?  I'm guessing that its
> use is for field work; does that mean or imply spring (planting)
> daytime hours, mid-season (weed control) daytime, and fall harvest
> time.  Can it be turned off when "not in use ?"  If so, who controls
> the on-off ?
> 
> Will the good will generated by the useage of you tower be worth
> whatever "problems" they system will cause ?  Or, put another way,
> will the ill-will cause by saying NO without really good reasons be
> worth the enhanced operating conditions ?
> 
> Either way, good luck !
> 
> 73 Donn
> WA2VOI/0
> 
> ----- Original Message ----- From: "Arliss" <w7xu at w7xu.com>
> To: <nlrs at mailman.qth.net>
> Sent: Friday, June 13, 2014 3:10 AM
> Subject: [NLRS] GPS and RTK
> 
> 
> >
> >
> >Hi,
> >
> >A couple of my farmer neighbors have asked me if I would allow
> >placement of an RTK transmitter on one of my towers.  I'm
> >wondering if anyone here has had any experience with this and/or
> >has any knowledge regarding the potential for interference to my
> >ham station.  At this point, I'm not even sure what frequency the
> >RTK unit operates on.
> >
> >Thanks & 73,
> >
> >Arliss  W7XU
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-- 
Chris Elmquist