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Apr 21, 2011, 12:49 PM
Registered User
Discussion

Did my first FPV flight today, but still have some video range problems


Today I did my very first FPV flight, and it went ok for a first flight. But I still have some problems with the video gone bad, at about 400 meters away from ground station.

I'm using a 500mw Lawmate Video Tx/Rx and a 8 dbi CP antenna. My Video tx is located at the tail on my EasyStar, and I use a ferritring and a capacitor before my camera - which is located in the nose of my plane. I only use one Lipo to power all gear/motor. For controlling the plane, I'm using Thomas's Scherrer 433Mhz LRS.

I'm almost out of ideas, of what to do, to get a better range.

On my CP antenna, I have the long wire running to my video Rx. I have been told to make it shorter, and on my FPV pod, the wire running from the lipo to the camera, might be a bite too long. But could those two wires (pod and CP antenna) prevent me from getting a video range at more than 400 meters ?

I have added some photos of my setup.
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Apr 21, 2011, 12:57 PM
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techspy's Avatar
Since you are using one battery for everything, have you checked to see what the voltage going to your video TX is at when your motor is running? If it goes down from 12v, that could be an issue. I had a similar situation. You can add a small 800mah, 3s lipo just for your video equipment and see if that helps. Otherwise, you can try something like this. I have one and it works great.

http://www.dpcav.com/xcart/product.p...cat=252&page=1
Latest blog entry: My Esprit Saga
Apr 21, 2011, 01:04 PM
http://drone-pilot.blogspot.fr
lovegroove's Avatar
With a 500mW video tx, you should be able to get 400m with no antenna on the receiver. I'd suggest that something is seriously wrong with your setup. Are you sure that the cable from the patch has the correct sort of plug? Sometimes they come with RP-SMA connectors that don't have the centre pin, but the plugs will still mate together.
Apr 21, 2011, 01:06 PM
Registered Loon
Blackrat's Avatar
i struggled with range with the std rubber antennae , do yourself a favour and make an inverted V , made my video 100% better
Apr 21, 2011, 01:47 PM
CD-ROM Junkie
Art Newland's Avatar
"On my CP antenna" does this mean circular polarized?
Apr 21, 2011, 02:09 PM
http://drone-pilot.blogspot.fr
lovegroove's Avatar
Quote:
Originally Posted by Art Newland View Post
"On my CP antenna" does this mean circular polarized?
Yes
Apr 21, 2011, 02:11 PM
Out of the way, Peck!
In the middle picture it looks like a stock rubber duck antenna on the video tx on the plane...those antennas generally suck.

Try bending up one of IBCrazy's 3-lobe Cloverleaf antennas with a short 12" lead between it and the video TX for the plane, and bend up a 4-lobe Skew Planar Wheel antenna for the groundstation video RX.

Also, having a 'long wire' between the receiving antenna and the video receiver is bad...at higher frequencies long coax leads 'attenuate', or reduce, signal strength. Probably no more than 12" to 18" is best.

If you want to mount your groundstation video rx up high for better signal like i do, use a short coax between the antenna and the rx, and a long video rca cable pumping a video signal from the rx to the LCD or goggles.

I don't run 900mhz for video, so i'll leave it up to other people to tell you whether you need a dual-notch filter between the plane's video tx and it's antenna. And are you running an LC filter between the battery and your avionics if you are using a single battery?
Apr 21, 2011, 02:53 PM
Registered User
Quote:
Originally Posted by techspy View Post
Since you are using one battery for everything, have you checked to see what the voltage going to your video TX is at when your motor is running? If it goes down from 12v, that could be an issue. I had a similar situation. You can add a small 800mah, 3s lipo just for your video equipment and see if that helps. Otherwise, you can try something like this. I have one and it works great.

http://www.dpcav.com/xcart/product.p...cat=252&page=1
I have thought about using two lipos, but I'm using a LC filter to prevent noise getting to the camera. The noise in the picture, only gets there, when I reach about 400 meters - if I turn back again, the picture is perfect.

My camera should work between 10.8v - 13.2v and I only fly on fully charged lipos.
Apr 21, 2011, 02:55 PM
Registered User
Quote:
Originally Posted by lovegroove View Post
With a 500mW video tx, you should be able to get 400m with no antenna on the receiver. I'd suggest that something is seriously wrong with your setup. Are you sure that the cable from the patch has the correct sort of plug? Sometimes they come with RP-SMA connectors that don't have the centre pin, but the plugs will still mate together.
I just checked my CP antenna. I have the center pin.
Apr 21, 2011, 02:57 PM
Registered User
Quote:
Originally Posted by Blackrat View Post
i struggled with range with the std rubber antennae , do yourself a favour and make an inverted V , made my video 100% better
I don't know anything about the inverted V antenna, but it sounds like something to go for. But I'm not using the stock rubber antenna on my video Rx.
Apr 21, 2011, 02:59 PM
NDw
NDw
Registered User
nvm, misread
Last edited by NDw; Apr 21, 2011 at 03:05 PM.
Apr 21, 2011, 03:01 PM
Registered User
Quote:
Originally Posted by Oddmar View Post
In the middle picture it looks like a stock rubber duck antenna on the video tx on the plane...those antennas generally suck.
Yes, it is the stock rubber antenna.

Quote:
Originally Posted by Oddmar View Post
Try bending up one of IBCrazy's 3-lobe Cloverleaf antennas with a short 12" lead between it and the video TX for the plane, and bend up a 4-lobe Skew Planar Wheel antenna for the groundstation video RX.

Also, having a 'long wire' between the receiving antenna and the video receiver is bad...at higher frequencies long coax leads 'attenuate', or reduce, signal strength. Probably no more than 12" to 18" is best.
I have the long wire from my Rx CP antenna to my video Rx. I will try to make i shorter before my next flight.

Quote:
Originally Posted by Oddmar View Post
If you want to mount your groundstation video rx up high for better signal like i do, use a short coax between the antenna and the rx, and a long video rca cable pumping a video signal from the rx to the LCD or goggles.

I don't run 900mhz for video, so i'll leave it up to other people to tell you whether you need a dual-notch filter between the plane's video tx and it's antenna. And are you running an LC filter between the battery and your avionics if you are using a single battery?
Yes I use a LC filter between Lipo and the camera.
Apr 21, 2011, 04:02 PM
Registered User
Surprised nobody has asked this yet...where are you flying? (what type of terrain)

- Jeff
Apr 22, 2011, 01:38 AM
Epic Huckin'
paintball_kidz's Avatar
LC filter should be between lipo and vtx, no?

Also is that stock antenna linear?
Apr 22, 2011, 02:03 AM
Registered User
Quote:
Originally Posted by jkarnacki View Post
Surprised nobody has asked this yet...where are you flying? (what type of terrain)

- Jeff
Later today I will post some photos from my flying field.


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