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Old Aug 03, 2010, 10:13 AM
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to combat multipath interference you can use a directional antenna like a patch or yagi and keep it pointed away from the interference source. Another is to have a diversity setup in your ground station. The idea is both receivers will not get the interference at the same time. The antennas should be separated by a multiple of half a wavelength.

My reception improved alot when I got a diversity setup with 2 patch antennas.

Morris
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Old Aug 03, 2010, 10:21 AM
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do you know what 1/2 wave length is for 2.4 ghz? I have diversity, one rx with a patch and the other with an omni for close in/behind the patch flying, but they are positioned very close to each other. I'm working on setting up the antenna tracker so that should eliminate issues with the omni..

Oh and I was looking at the video again, carefully to see where I picked up the most interference. Seems like when I was near the building in a climb (or near the building at all) and when the plane we pointed directly at the GS. The latter could mean the battery/electronics were blocking the signal to some extent. That seemed to improve as I got closer to home. I noticed a similar effect with my SS, except it was the camera and the motor that I believe were blocking the signal...
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Old Aug 03, 2010, 11:37 AM
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Quote:
Originally Posted by ashdec87 View Post
do you know what 1/2 wave length is for 2.4 ghz? I have diversity, one rx with a patch and the other with an omni for close in/behind the patch flying, but they are positioned very close to each other.
See this post. It explains more about antenna position to reduce interference.
http://www.rcgroups.com/forums/showp...&postcount=989
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Old Aug 03, 2010, 11:41 AM
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thanks, I'll adjust things a little and see if that helps.
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Old Aug 03, 2010, 12:29 PM
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Why are you guys talking video interference problems on Skywalker's thread?
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Old Aug 03, 2010, 03:04 PM
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Cuz it has to do with a skywalker

Anyways, I'm pretty sure most of the problem(s) were caused by the battery/ some sort of multi-path issue. I flew at a forest preserve and was able to make it out to over a mile with very little issues. In fact it was clearest when I was really far out. I cant explain this, but I got a lot of interference near the beginning of the flight, but when i flew over the same place later it was fine.... strange. I wonder if it has to do with the higher power setting.. On the way back I did notice that the battery/electronics certainly did block the signal as I got a lot of glitches until I turned about 30 degrees away from home. Once I got close all was good..

Anyways, the plane did GREAT going out that far. Handled the bumps and light wind extremely well. Still having issues with the INSANE glide ratio. You'll see on the video but I was over 1/4 mile out, zero throttle at about 300-400 feet and it glided all the way in... and I ended up overshooting into grass cuz it wouldnt slow down..lol Crazy little plane.

Here's the flight. I really need to get a better recorder...

SW8310 (6 min 53 sec)
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Old Aug 03, 2010, 05:09 PM
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SON OF PALEFACE's Avatar
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yeah right , the shape and the epp foam is causing interference..............
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Old Aug 03, 2010, 07:20 PM
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Ash,
Good to see that you have tracked down the issue...

Don't know what you are actually viewing and if it is the same as the video , what type of recorder ? tape or SD card.."Ground station" on the cam with OSD.

Has the HD cam got AV out ?? ..

Tape is the better medium, believe it or not than SD card.. other than direct to Hard Drives like and Archos recorder. ( that of course is a new tape not a reused one over and over ) many would debate that..

BTW "all foam in invisible to radio frequencies it is the hardware that is not. "

One way to test if the foam ,tape, covering, cheap heat shrink is to put a small piece of it in a micro wave oven for 15 sec if you get any heat ie: "Warm to HOT---> melt" then is has radio interference properties.. (heat shrink being the most important not to have when two section touch on and extension lead....

What do you have hanging out on the right wing

Cheers
Bear au ( Richard )
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Old Aug 03, 2010, 07:25 PM
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"BTW "all foam in invisible to radio frequencies it is the hardware that is not. "

D'you think ??..
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Old Aug 03, 2010, 08:54 PM
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I use a apitek camera to record. What I'm seeing is similar to what's recorded but the recorder doesn't show static. It just has glitching if that makes sense. Hd cam does have av out but I don't use it since the camera can't be out on a pan tilt easily. The gps is on the right wing
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Old Aug 03, 2010, 09:18 PM
First to go over 106K feet
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Skywalker fuselage plugs for sale

4 inch plugs for sale here:

http://www.rcgroups.com/forums/showthread.php?t=1286250
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Old Aug 03, 2010, 09:34 PM
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Quote:
Originally Posted by SON OF PALEFACE View Post
"BTW "all foam in invisible to radio frequencies it is the hardware that is not. "

D'you think ??..
Yes , in the context of foam used in general building of our RC planes..
On a scale of 1 to 10 it would be a 1. we are talking about the EPO SW

However there is foam/polymers products made by designed to shield EMI/RFI and these usually have a ferromagnetic or conductive filler in the mix.

I am sure you can do you own testing with a SWR meter and foam EPO sheeting placed in front of the patch or dipole antenna or even over the GPS module ( this may drop the weakest Sat ) and see the results compared to balsa or batteries,wires,people, etc.

If your only factor is RFI/EMI is due to your foam plane then you have a near perfect system..

It is the hardware and its placement that is the major hurdle, and of course the ground station which in most cases is never set right.

Enough on the subject.. as it was said this is a SW thread and my comment was in relation to the Skywalker !

Cheers
Bear_au
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Old Aug 03, 2010, 09:59 PM
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Quote:
Originally Posted by ashdec87 View Post
I use a apitek camera to record. What I'm seeing is similar to what's recorded but the recorder doesn't show static. It just has glitching if that makes sense. Hd cam does have av out but I don't use it since the camera can't be out on a pan tilt easily. The gps is on the right wing
Ash,
Good video and a mile out. you really need to get a better cam for OSD if you are getting that range.. the DX201 cam there a nice unit..
Just edit out the drops outs as most do.. and we wonder, why don't they get interference... well let me tell you they do they just cut it out.

I'm sure you will find the reason just do one change at a time to what you think might be giving you the problem until you find it. Otherwise just enjoy the 1 mile trip and view

I even bought high quality shielded AV cables to run from the Oracle Video Diversity Controller and that made a 60% improvement alone to both Recorder and the FatShark Goggles.
Again I come back to the ground station setup..

Cheers
Bear_au
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Old Aug 03, 2010, 10:11 PM
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Actually this camera might edge out the 201. The recorder doesn't do it justice. I hooked it directly up to my tv and it was and amazing picture.
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Old Aug 03, 2010, 10:42 PM
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Quote:
Originally Posted by ashdec87 View Post
Actually this camera might edge out the 201. The recorder doesn't do it justice. I hooked it directly up to my tv and it was and amazing picture.
Hi Ash,
So what is the cam and VTX setup you have?

I know it is the Eagle tree OSD..
I am working on a Radian with Eagle tree pro OSD not sure which cam yet for that might use the KX191, but the SW will be the RVOSD gen 3. with DX201 both system run on either 900MHz or 1.3 GHz.. VTX depends on what is around on the day with interference.. I still use 2.4Ghz but gets a bit of interference in the city with all the 2.4 Wi-Fi around etc..


Cheers
Richard
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