[TriEmbed] Long range digital communication (long range wifi, XBee?)

[Charles West]

Hello!

I'm in Lansdale, PA now but I was hoping I might be able to pick you guy's
brains.  My current big project is trying to build one or more robots to
deliver food/drinks on golf courses.  I'm currently trying to figure out
the best way to maintain continuous(ish) contact between a access
point/basestation at it's base of operations and 1 or more robots operating
on the course.

At a minimum, I would like to have the robot report its basic status
(battery percent, GPS position) but it would also be great if it could
stream video when required to allow teleprescence steering or determination
of what is going on.  The robot would probably be about 1 km from the base
station at max.

I'm currently considering 3 possible solutions but I'm pretty open to ideas:

1.  Use a mobile hotspot/cell modem:
        For fixed $130 and monthly $20, I can get a mobile hotspot which
provides one gig of data per month and more data for $5/gig.  If I keep the
reporting really light, this could work but the communication would have to
be kept pretty limited.

2.  XBee:
         These modules seem to float somewhere between $25 and $60 in
prices, so a pair would be somewhere in the $50 to $120 range.  Sparkfun
had a good guide to XBee (https://www.sparkfun.com/pages/xbee_guide) but
they are listing almost all of their products as retired (besides old
series 1) and most of the stuff I read about XBee is from 2015-2016 so I am
not sure what the best options are anymore.  In any case, it looks like it
would provide a low baud rate connection over the desired range.  The main
problem is that it requires working through XBee and making my basestation
have to have special software to forward information.  I'm also not sure
about security and it is certainly not going to be streaming video.

3.  Long range Wifi:
        Rodney's done some work in this area before with his weather
balloon projects.  I don't recall off the top of my head how far he managed
to get but I do remember he had to use higher power than allowed without a
higher grade amateur radio license.  That power level would not work for a
commercial operation.  There are some companies that are selling solutions
aimed at farms (http://ayrstone.com/www/?v=7516fd43adaa) and there seem to
be off the shelf solutions that can get 500 ft (mostly aimed at hotels).
The hotel systems seem to be in the $350 range and the farm systems in the
$500 or so.  The robot could use a high gain antenna, but it is not clear
how much it helps.  These systems have security built in and potentially
can stream video if the range is long enough.  Like hotspots, writing
software for them would also be easy.

What do you guys think?

Thanks,
Charlie
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