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Old Sep 05, 2012, 10:59 PM
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compuatic's Avatar
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Antenna tracking using RSSI vs GPS location

I am planning on building a diy arduino based antenna tracker. Can someone go over the advantages of tracking using rssi vs gps? Rssi seems like a simpler path and the algorithm should not be more complicated either.
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Old Sep 06, 2012, 11:47 AM
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help
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Old Sep 06, 2012, 01:07 PM
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aaronredbaron's Avatar
United States, IL, Champaign
Joined Apr 2002
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have you looked at IBCrazy's antenna tracker? he used RSSI....
http://www.rcgroups.com/forums/showthread.php?t=1337608
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Old Sep 06, 2012, 01:09 PM
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mrfliboy's Avatar
USA, IL, Round Lake
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And heres GPS style, arduino based

http://www.rcgroups.com/forums/showt...ntenna+tracker
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Old Sep 06, 2012, 02:04 PM
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Canada, ON, Milton
Joined Jan 2009
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Rssi only needs a couple of vrxs to work. Gps needs to be either data transmitted over audio channel, included in video(VBI) or direct. I've done a direct system using an Arduino to decode and a pair of 2.4ghz Xbee's.
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Old Sep 06, 2012, 03:31 PM
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United States, MA, Sturbridge
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RSSI tracking can be a problem. If someone else fires up something in your freq range your tracker will focus on it instead of your plane.
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Old Sep 06, 2012, 04:01 PM
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compuatic's Avatar
San Francisco, CA
Joined Jun 2002
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Guys, thanks for the links and info but i'm not asking for implementation help or how to. i'm trying to figure out why one path would be better than the other.

slowjett, if someone interfers with the frequency then the vtx will go out of whack too which is a bigger problem. the tracker loosing it would be a second order effect.
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Old Sep 06, 2012, 04:22 PM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
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Very few people use tracking, and fewer still have likely tried both so
not many can answer from personal experience.
One advantage to GPS based is you only need one antenna and it
can run off a pan&tilt mount, while all the RSSI based ones I know of
use 2 or 3 antennas for pan only with no tilt. Turning 2-3 antennas may
be practical at 5.8 and 2.4 Ghz, but not so much with big 1.2-1.3Ghz
and 900Mhz high gain antennas.
Not being able to track straight up may or may not be an issue for you.

It is relevant what happens when someone else's signal
swamps yours. RSSI based will always turn to face the strongest
signal, and then when they switch off it may not find your plane's signal
again. With GPS, it'll likely just stop actively tracking while the GPS
signal is gone, but resume as soon as the interference goes away.

That said, I was recently flying with a popular GPS based tracker and
when I flew into some static (behind trees and structures), the tracker just
gave up and spun around to north which meant I lost A/V signal completely
and potentially permanently.
Only way to recover was to physically spin the tripod head back around
till it picked up the signal, and then as tracker turned itself, had to turn
the tripod back again. Very annoying. Seems like a softare bug to me
as I'd have expected it to just freeze where ever it lost the signal
and wait for it to come back. Any other behavior almost guarantees
eventual loss of the plane.

BTW, in case it's not obvious why an RSSI tracker uses 3 antennas,
if you try to use 2 antennas, you typically aim both out a bit to each side,
and then try to keep the RSSI balanced, but that means pointing both
antennas a little off center all the time (never flying the center of the beam
of either antenna).
Only way way to avoid that is to use 3 antennas. 2 dedicated to tracking,
1 more in the center for the A/V signal.


ian
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Old Sep 14, 2012, 05:04 PM
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United States, UT, Sandy
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Quote:
Originally Posted by compuatic View Post
I am planning on building a diy arduino based antenna tracker. Can someone go over the advantages of tracking using rssi vs gps? Rssi seems like a simpler path and the algorithm should not be more complicated either.
Coincindentally, I just built one, and posted it in the FPV forum. Here is the link. I would love to cooperate on improving it. I just flew with it the first time to day and was generally satisfied with a few small problems.
Dick
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Old Sep 14, 2012, 05:04 PM
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United States, UT, Sandy
Joined Nov 2010
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Quote:
Originally Posted by compuatic View Post
I am planning on building a diy arduino based antenna tracker. Can someone go over the advantages of tracking using rssi vs gps? Rssi seems like a simpler path and the algorithm should not be more complicated either.
Coincindentally, I just built one, and posted it in the FPV forum. Here is the link. I would love to cooperate on improving it. I just flew with it the first time to day and was generally satisfied with a few small problems.
Dick

http://www.rcgroups.com/forums/showt...hlight=arduino
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Old Mar 24, 2014, 10:35 PM
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quadcopter007fpv's Avatar
United States, CA, Riverside
Joined Feb 2012
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here is the one i use ,rssi based
http://www.rcgroups.com/forums/showthread.php?t=2024405
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