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Greetings.

If you look at http://www.vimeo.com/6561467 , initially you'll see lots of jitter on the pan & tilt channel. Perhaps not surprising, it's 300m out and flying towards the pilot - with the aerial lying down the fuselage, what is the cross-sectional area of aerial exposed to the transmitted signal?! Square root of zilch, but my (pricey!) Multiplex IPD Synth 9 channel receiver works fine - okay, I'd expect anything much apart from a low-range park flyer receiver to do okay too.

However, even when the plane is at right angles to the transmitter (20-24 seconds into the video), there is still noticeable, and really irritating, jitter on the pan & tilt servos; the picture continually shudders, even if only on a small scale. Probably not an issue if you're just flying, but noticeable for FPV.

I've only realised this is an issue since comparing video from a 2nd FPV plane. I suddenly realised that video from this 2nd plane doesn't have this continual, slight, jitter. It also uses a different receiver (Hitec HS09RQ)...

Anyone else had experience of this effect - continual, small-scale 'jitter' on the pan & tilt channels? Not the same as glitching, almost as if the DSP in the receiver is imposing some jitter?

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yes I had it until I fitted a servo slow in the servo lead. Unfortunatly the one I used is not high enough res so gives a notchy movement to the servo when its moved but keeps it still ok the rest of the time which is still an improvment.

Terry

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sounds similar to a servo issue im facing now. what servos are you using to pan / tilt? i had the same subtle intermittent jitter with hxt900s (cyclic), gws park hpx f (tail) & a mg90 (spare). i tried braiding the wire, making a faraday cage out of aluminum foil (this worked some, but only if the cage wasn't connected to ground) numerous winds on a ferrite, and installing caps on the servo motor. the aluminum wrap produced the only noticable change. just before throwing in the towel i spotted a esky 8g digital servo sitting on the table and decided it was worth a try. SUCCESS! my analog servos won't be flying fpv as it stands right now. i can't think of any other practical filtering or sheilding techniques so it looks as if i'll be investing in some digital servos in the near future.

i'll most likely visit my LHS where i can try before buying. hope this helps! cheers!

-sj

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after further tinkering and reading i came to the conclusion that my antennas were most likely the main culprit. pulled them both off and compared... two different lengths! one of them measured correctly for a 1/2 wave 1.2ghz! thanx RV! <_< so i borrowed one of my dad's swr/wattmeters and started cutting copper. i was able to get the swr down and the power up, but the swr was still too high at 1/2 wave. next i tried a full wave, nice! swr was almost gone and power was just under 500mw. the tx runs MUCH cooler and my analog servo glitching issues have gone from unusable to almost non-existant. i ended up building a 1/2 dipole and so far so good. so anywho, if you haven't already done so, check your stock antenna tuning!

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