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Old Jun 15, 2012, 09:46 PM
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Teamsherman's Avatar
Australia, NSW, Picnic Point
Joined Aug 2011
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Originally Posted by jb_bak View Post
Teamsherman, you have a rangelink and osd pro??!? Boy, if you could give me some more details of your wiring, I would appreciate it! I'm doing something wrong, if you actually got it working.
All I run us the single wire from RL RX rssi to the OSD pro temp 1 input with a ferrite ring having ten wraps around the ring and in the windows software I enable rssi input to temp 1 input just as it says in the OSD manual then I ran the analysis wizard. Works fine for me.
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Old Jun 16, 2012, 04:43 AM
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Switzerland, LU, Buchrain
Joined Aug 2006
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Originally Posted by sdueck View Post
While I am waiting for my rangelink system to come, I figured I better make sure I know how best to mount my antennas.

How are you guys mounting them? I know it should be as far away from the video Tx and camera as possible, but what about orientation? I plan to use the system on a variety of planes, from a flying wing, to an easyglider, to a quadcopter. Yes, I will be putting this on a quadcopter. I have 2.4 spektrum on it now, and the last thing I want to do is outfly its range, which I have gotten really close to doing.

Scott
Scott,

You want the antennas to be oriented vertically. This is also important on the transmitter side of things. Many people mount their tx modules below the transmitter leading to a mostly horizontally oriented antenna. THATS BAD!

With linearly polarized antennas things are like this. If both antennas are vertical, their common surface (if seen from behind one antenna towards the other) define how much of the signal is received. The more they are tilted against eachother, the less of the signal arrives. In the extreme case (antennas 90 degrees to eachother, alas one vertical, the other horizontal) you experience a loss of the signal of 12dB. That's HUGE, (almost a factor of 16 times less than what it would be if both antennas were oriented the same).

What you also must consider is the fact that dipole antennas (that's whats used on the rx end of things) as well as the stock tx whip both have a null along their axis. The radiation pattern resembles an apple seen from the side.

So, having both antennas horizontal (i.e. by mounting the rx antenna paralell to the wing) is no solution because of the null. If your plane would fly paralell to you, the null of the rx antenna would point towards you (which then would lead to a total signal loss) or if you would fly to the left or right of yourself, the null of the tx antenna would point to the plane with the same fatal result.

The latter is actually also the problem of the otherwise nice aproach of the turnstyle antenna that IBCrazy sells. There the "null" problem on the plane end is partially solved as this antenna forms a cross and is to be mounted horizontally. Then you also would have to hold the tx antenna horizontal and this would work as long as you fly in front or beihind yourself, but NOT to the sides. Of course, one could also use a turnstyle antenna on the tx side of things, but mounting that one so as it would work would mean to place the tx module onto a tripod and have the tx turnstyle antenna horizontally on top of everything. Doable but a bit clumsey.

So, bottom line is mount the antennas vertically. In case of the rx dipole I use a drink straw as those can be tilted back when the plane lands in the grass and simply bent back into the vertical direction before the next launch.

HTH

Markus
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Old Jun 16, 2012, 07:57 AM
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Quote:
Originally Posted by Teamsherman View Post
All I run us the single wire from RL RX rssi to the OSD pro temp 1 input with a ferrite ring having ten wraps around the ring and in the windows software I enable rssi input to temp 1 input just as it says in the OSD manual then I ran the analysis wizard. Works fine for me.
That is exactly what I have tried many times. Something must be broken here.
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Old Jun 16, 2012, 10:33 AM
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United States, CO, Littleton
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Originally Posted by markus123456 View Post
So, bottom line is mount the antennas vertically. In case of the rx dipole I use a drink straw as those can be tilted back when the plane lands in the grass and simply bent back into the vertical direction before the next launch.

HTH

Markus
That all makes sense. I figured that was the case, as I have a little understanding of linear antennas. I'm new to dipoles though.

Mounting vertically on most of my planes will be easy, but on my wing it'll be difficult. Is there any possibility you can position the dipole at a 90 degree angle to itself, thus forming basically a "v"? Would this eliminate the null area at the end of the antennas? Obviously this would have to be positioned to match the transmitter antenna orientation.

I'm not looking to win any distance contests, I just want a reliable signal to 5 miles or so.

Thanks for answering all my questions Markus. I greatly appreciate it.

Scott
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Old Jun 16, 2012, 10:38 AM
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Originally Posted by sdueck View Post
can position the dipole at a 90 degree angle to itself, thus forming basically a "v"?
That will be quite bad for reception, what other people have suggested is to use a drinking straw for the lower portion, so it remains straight during the flight and simply bends back when landing without damaging anything.
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Old Jun 16, 2012, 10:46 AM
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Switzerland, LU, Buchrain
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Originally Posted by npre View Post
That will be quite bad for reception, what other people have suggested is to use a drinking straw for the lower portion, so it remains straight during the flight and simply bends back when landing without damaging anything.
+1, thats definately the best aproach. Uless you could feed the dipole i.e. mounted into one of the fins of said wing such that the antenna does not extend below the wing, but frankly speaking this is a pain as it most likely would require a longer coax which is something you should avoid.

Markus
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Old Jun 16, 2012, 11:02 AM
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Alright. Sounds good. I guess I'll try the drinking straw method. Thanks for the answers guys! Hopefully I'm not the only one who has these dumb questions...

Scott
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Old Jun 16, 2012, 12:47 PM
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Lakewood, Colorado
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Quote:
Originally Posted by markus123456 View Post
The more they are tilted against eachother, the less of the signal arrives. In the extreme case (antennas 90 degrees to eachother, alas one vertical, the other horizontal) you experience a loss of the signal of 12dB. That's HUGE, (almost a factor of 16 times less than what it would be if both antennas were oriented the same).
Cross polarization loss is a lot more than -12dB. -30 to -40dB is typical.
Worst case is, as you mentioned, the two antennas pointed at each other where loss is
essentially infinite.

I've generally not found it critical that the ground plane (lower part of antenna) be
perfectly straight. I usually mount the upper half of the antenna in a vertical tube,
and let the lower half dangle. I think having it not exactly in line with the upper half
also helps reduce the null off the tips (like the Vee antennas we often use for video).

ian
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Old Jun 16, 2012, 02:55 PM
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Woohoo, ordered my RL last Friday, got it today...... Now to install.....
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Old Jun 16, 2012, 04:49 PM
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Guys, everything works great except now my Skylark trace 3 shows erratic voltages and current readings. It was actually showing 30v at one point on a 4 cell battery. Do I have to recal the current sensor now? I didn't change anything on the OSD itself, just the receiver and transmitter.......
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Old Jun 16, 2012, 07:47 PM
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So remove the RSSI line and see if the problem persists. If so, it has nothing to do with RL.

ian
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Old Jun 17, 2012, 01:20 PM
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Maybe I'm missing something but I don't understand what RSSI has to do with the current readings......

Anyway, I tested it again and it worked fine. Not sure but now it works fine.
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Old Jun 19, 2012, 02:24 PM
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United States, CO, Littleton
Joined Nov 2006
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Hey guys, does anyone know why the manual is showing up with question marks for me? This is the v1.4 manual from sid's blog. The v1.3 one from aceFPV does the same, just not as bad. I assume I am missing a font or something...

Thanks,
Scott

P.S. Rangelink came today. I just have to go pick it up from the Post Office in the morning...
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Old Jun 19, 2012, 02:35 PM
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United States, TX, Brenham
Joined Jul 2011
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Quote:
Originally Posted by sdueck View Post
Hey guys, does anyone know why the manual is showing up with question marks for me? This is the v1.4 manual from sid's blog. The v1.3 one from aceFPV does the same, just not as bad. I assume I am missing a font or something...

Thanks,
Scott

P.S. Rangelink came today. I just have to go pick it up from the Post Office in the morning...
No, other than a problem with your acrobat reader software or a font like you said. Perhaps try re-installing it. In the meantime, you can use google docs to view it.

http://docs.google.com/viewer?url=ht...l%2520v1.4.pdf

PS...thanks for the heads up on the 1.4 manual, I missed its release and will get it mirrored.

-Pat
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Old Jun 19, 2012, 04:55 PM
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United States, CO, Littleton
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Originally Posted by h0tr0d View Post
No, other than a problem with your acrobat reader software or a font like you said. Perhaps try re-installing it. In the meantime, you can use google docs to view it.

http://docs.google.com/viewer?url=ht...l%2520v1.4.pdf

PS...thanks for the heads up on the 1.4 manual, I missed its release and will get it mirrored.

-Pat
Thanks! It works in GoogleDocs. I will stick with that until I feel like dealing with adobe/preview.

And you're welcome about the heads up!

Scott
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Last edited by sdueck; Jun 20, 2012 at 05:48 PM.
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