Bad Video Range ~

[jmc67]

I'm not sure why video range is bad when I go about 25ft above the tree line and start to lose video signal. Static first then loss.
I have setup the ImmersionRC 600mw transmitter - 5.8ghz on a DJI F450 frame. On the frame I have the gopro2 in front and DJI GPS on the back. For receiver, I have the ImmersionRC Uno receiver (UNO5800).
For antenna I have tried using CP antenna and Spironet antenna. With the CP antenna installed on the front left leg, signal is horrible. With the spironet in the same leg, ok until I pass the tree line. Installing the transmitter in the back, having the spironet antenna upright veritical or upside down, signal is also bad but I can go a little higher. Now if I keep the spironet antenna horizontal, video is perfect. Is it recommended to have the anntenna placed this way? Also, I was using a 2s 800mah lipo to power both the transmitter and camera with no issue. I also tried a 3s 800mah and still had the same issue as stated above.


Bad video signal
View attachment 6078

Bad video signal
View attachment 6079

Perfect signal
View attachment 6080

Uno 5800 Rx
View attachment 6077

CP Antenna
View attachment 6081

 

[kloner]

just to go over some basics..........

the vu, has an led and you plug into it to program the naza is the noisiest dirtiest thing on your craft.

the rc control radio part, spektrum/futaba/etc needs to be as far away from the video transmitter as possible

the mast you got isn't sitting the antenna high enough. To do a quick dirt test, try securing the video tx upright so it shoves the antenna up in teh air and doa ground check, but that alone would fix alot, but every little thing makes a difference. when i say move stuff often a cm is better than less so any distance you can put in stuff helps. on my vu i wrap em with aluminum tape and reshrink wrap em, helps quite it down, never had a heat problem and i fly in up to 110f

The gps does fine back with the rc control, but the video tx hates them things

The video tx should be near the camera and get the wires nice and clean, nothing looped and tied off, everything with about an inch of extra wire so it can crash and live

a 5.8 mast should be a wavelength or two up, that is 3.333" and increasing by 1/4 wave is fine meaning increase in segments of .83" at at time. Seems i had the best luck at 1 to 1.5 wavelength up on that system/freq


the top and bottom of cp antennas are null and have no signal, whatever you do don't point that fore or aft, your gonna hit the null sooner than later like that, point it up or down. down is generaly ba on the f450 cause it gets whacked easily

shoot for a layout like this

you can see everything i described in text in them right there....... on my other rigs that had 5.8 and gps the gps is back in the back by the rc control receiver. Flew out to a mile and never blinked

not 5.8, but shows the sat

you can see the modified vu there with the tin sticking out of the wrap. has a hole where the light shines through still. Those switching power supplies are dirty by nature. Your video tx has one too but it's a cleaner filtered setup

 

[jmc67]

Thanks for the basics..... You say the VU produces alot of rf garbage. However, having the antenna in horizontal position gives me the best video without loss. I did initially have the fpv antenna on the left front arm with rc receiver just behind it on the plate and that did not work. I'm going to move the antenna to the front right arm and give it another try today weather permitting.

 

[kloner]

right, it'll be even better away from it

sometimes when your so far off, the littlest changes produce fake results....... when everything is right, you don't see any static whatsoever at any time. in hand, on your test flight, next thing you know you got no idea where you are your so far, etc.

Try moving stuff around. the try with the antenna pointing up woulda been your best bet if you'd have had a 90 degree elbow on the antenna and not curved it so it wasn't high enough anymore. i did that with my goggles, sucked till i made a mast to get it right. 5.8 love there antennas up away from motors, batteries and other metal stuff

again, just moving stuff cm makes a huge difference. it's a matter of knowing what to move. my suggestions worked for me on a few of these things. i love 5.8

 

[DucktileMedia]

I had some iffy performance with my 5.8 600mw tx the other day and I just unvelcroed the vtx and repositioned it a little differently and it worked flawlessly. Obviously they are very sensitive to their position in relationship to everything else.

 

[jmc67]

Ok, I moved the transmitter over to the right front arm and also installed a 90 degree elbow to the antenna.
Still have same issue. Quad is high above tree line and LOS. If I go higher the staic gets worse. I also tried putting transmitter in back under the quad belly.

I was able to shoot a quick video using my iphone. Here is the link: http://youtu.be/awWeBjx3k0g

View attachment 6085

 

[kloner]

straight overhead always has static like that, no wonder out the back was working,,,,,, the side which was pointed down was sending the signal.

Is that the main thing your gonna do with it? if it is, might be wise to go sideways like you mention having luck. When i'm looking at a monitor, it's usually no higher than that but 200 feet to thousands of feed away from me, not over the top. When i fly over myself i get that same exact junk

Go fly off ot the side of yourself, just for giggles, say as high as you are now, but stand to the side of the thing so the side of each antenna get to see eachother. The signal is coming out the sides, not top or bottom

this is the chart of what the signal coming out of your antenna looks like from the side. imagine the top and bottom of the picture is the top and bottom of the antenna. see how theres no signal there

imagine your quad the middle of that picture and your standing on -180

this is if you look down at the antenna from the top and how it radiates outward, similar to when you had it on it's side replaced what the pic above was top and bottom, except you made this top and bottom, see the signal radiate with no gap. that's why it was working, but man, that's an unusual way to use it

same thing here, except on it's side your quads in the middle and your on 270.....

http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_49_97&products_id=459

 

[jmc67]

Nope, this is just for testing. Actually the quad is not above the receiver but maybe about 10-20 feet out from my position. I also yawed the quad just to see what would happen. I'm gonna give a a fly run with the antenna on the right arm and see how things go.

 

[kloner]

that null circle i'm describing would vary for 20-30 yards around you over head. I'm talking get off to the side of the thing,,,, hundreds of feet. I don't know that i'd hover over it in the null zone like this, then say oh well, i'm gonna fly it. Any reason you can't test it off to the side.

Seriously, when you are doing stuff so far from right the false symptoms will never stop. You gotta get out and do normal stuff. if you need to fpv straight overhead like you were, use rubber duck antennas that came with it and lay them horizonal so there facing side to side, would be a rock solid way to fly that. You can always skin a cat, just gotta know where to start

 

[goraplx]

I have best clear signal with vtx under arm.
http://lh5.googleusercontent.com/-u5l14N0fpw8/UDzwWghukTI/AAAAAAAAe2Y/wlQXjF1IHHU/s1024/IMG_1654.JPG

 

[kloner]

makes since, roll with it. That's the furthest from the motors....pointed up it goes level with the motors. Your trying to avoid metal, carbon, anything reflective between it and you

 

[Bison52]

Beginner question. -- if I don't care that much about range, video used for LOS framing only, would I be just as well off with a 25mW tx and would the lower power mean less likelihood of interference with other on board electronics?

 

[kloner]

yes..... i'd get 100 watts just to get away from the 25's price. it's a regional thing needed in europe so they get a premium

 

[goraplx]

Guys do you think if I swap my vtx from 600 to 100 or 25mW should It improve signal quality?. I m flying up to 400m only.

 

[kloner]

It can if everything else is perfect. the best way to make it work really good is for everything to be placed and setup the best it can. know it's grey, but that's how this is. every little bit of interferrence gets built up till it sucks. one little thing can do it. Bad connector on a wire, loose antenna, theres so many factors

 

[jmc67]

I will give it a shot flying it forward some few hundred feet and see how it goes this coming weekend. I'm just confused because I have seen many other fpv videos where the quad is close to the receiver with no issue. Perhaps they are using a patch antenna? Perhaps I guess. Really do appreciate your time.

 

[jmc67]

I have a question. Is it possible to use a cloverleaf antenna on both receiver and transmitter and are there any benefits in doing so? What about doing the same using skew-planar antenna? Just curious.....

 

[kloner]

you can, the advantage is ease and size is super minimal. disadvantage for 5.8 is it's just not enough to get very far. the 5.8 really comes alive with directional patch antennas like crosshair, helical, etc. a helical pointed to the north can still be flown south of you, i usually get 1200 - 1500 feet when my tracker used to stop before i'd look over cause it'd flicker a couple times. if my expectations weren't so high i'd probably never known. it's just out front is like a xray machine, they really pick up a clean signal, makes kloner happy

 

[goraplx]

helical 3-4 turns = wider angle of operation , but shorter distanse ? is that right kloner ?

 

[kloner]

yea, 3 to 4.5 turn are super efficient, kinda work all around with an eemphasis on the front. a 12 turn or cannon is super tight, not so good to the sides and rear but man, out front is rock solid, behaves more like a lower frequency but kinda has to be spot on 30-40 degree beam if i remember right. almost tracking material.......