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Thread: 2.4ghz Control Megathread - Spektrum, Futaba, FrSky, etc

  1. #11
    I Drink to Forget PDXDave's Avatar
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    Quote Originally Posted by sim_io View Post
    ...its not the frequency its their lack of knowledge and testing.
    Absolutely true! (at least in my case) That's why I keep asking questions. Thanks for the input.

  2. #12
    Crashing Vitamin J's Avatar
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    The biggest issue with Spektrum is the lockout, while it may come back in "seconds," that is a long time in FPV. The 2nd biggest issue is penetration. Someone posted a video awhile back asking why he was getting lockouts about 200m from where he was standing at plenty of altitude, the answer, he was flying behind himself and his body was blocking the signal.

    Personally, I lost a plane to a lockout on a DSMX system about 500m from where I was standing. Lockout because I violated the fresnel zone, my fault true enough but if I had 72mhz then; when I raised my tx over my head I would have regained control immediately instead of having to wait "just a few seconds" as the video went to black.

    I just picked up a FrSky 2.4ghz system with the intention of using CP antennas and a 1w booster. On top of that FrSky is known to "glitch" like 72mhz when it receives bad packets, this means it doesn't lock out and it will regain signal nearly as fast as 72mhz, which is to say almost instantly.

  3. #13
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    All the anti spektrum crowd are doing is sharing their experience...

    Bear in mind the majority of comments will have been in reference to DSM2 protocols, and not the relatively new DSMX which is much more similar to the futaba FASST implementation that "everyone" recommends if you must use 2.4GHz FPV... At that point it really just becomes the 2.4GHz characteristics that are limiting.

    Truth be told I've been using Spektrum for short range FPV (DSMX though) without so much as a hiccup. It's my belief that DSMX at least is perfectly adequate for short range FPV (i'm talking park flyer style FPV here) as long as the installation is done correctly and it's limitations are known and adhered to.

    For me personally, the biggest driver to go to an LRS was to give the option for 2.4GHz video which is pretty much the best "legal" frequency I have available, and of course to remove any nagging worry of flying out of range.
    Last edited by Zeeflyboy; 5th April 2012 at 02:33 PM.

  4. #14
    RTFM aeryck's Avatar
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    Zee, thats pretty much been my opinion from the start. Yes, dsm2 has its limitations, specifically that it picks two channels and only uses those two channels. Much more succeptible to interfeerence than dsmx, which hops the entire band similar to fasst.
    Far better is it to dare mighty things, even though checkered by failure; than to take rank with those who neither enjoy much or suffer much, because they live in the gray twilight that knows not victory nor defeat.

  5. #15
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    Yeah, but remember DSMX has its limitations too...

    In my opinion it works, pre mentioned caveats aside, but that doesn't mean it's optimal

  6. #16
    Navigator Airborne's Avatar
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    72mhz isn't all it's cracked up to be. Yes it has a few upsides, but in the end you are trusting your link to a tiny 20KHz sliver of bandwidth with no encoding or redundancy. You can still get shot down by another 72MHz radio. You could even be "FPV hijacked" by someone else who can see your video feed and knows what channel you are on.. FM's capture effect means whoever has the strongest signal wins. A corona doesn't care if it's positive or negative shift FM, making it even easier. (This is not likely, but 100% possible)

    Know what you have, stay within its limits and you generally don't have problems.

  7. #17
    Is that a drouuune!? sim_io's Avatar
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    Quote Originally Posted by Airborne View Post
    72mhz isn't all it's cracked up to be. Yes it has a few upsides, but in the end you are trusting your link to a tiny 20KHz sliver of bandwidth with no encoding or redundancy.
    72Mhz was the standard of remote control for decades, I think its proven its redundancy mileage far than any other link. There are people still flying $5,000 turbine RC jets on their trusty 72Mhz. You make it sound like people on 72Mhz have airplanes falling out of the sky because of a "tiny" component. To your surprise components now a days have gotten even smaller, you just have to compare the size of a bulky Futaba 72Mhz receiver to a shrunk 2.4Ghz receiver the size of a nikel so by your logic 2.4Ghz is inferior because its smaller? Also I don't get the part where you mention that 72Mhz has no encoding, Futaba has PCM receivers or Pulse-code modulation. They actually encode the signal digitally into bits of information to the receiver.


    Quote Originally Posted by Airborne View Post
    You can still get shot down by another 72MHz radio.
    5 to 10 years ago I would agree but I think its safe to say that the entire r/c hobby has moved to 2.4Ghz, yes there are old farts who still use 72Mhz but they are at the local flying fields, just avoid them.

    Quote Originally Posted by Airborne View Post
    You could even be "FPV hijacked" by someone else who can see your video feed and knows what channel you are on..
    The term fpv hijacking is a first, you are paranoid. Just for the fun of it, let me try to create a not so typical scenario. So I'm flying one mile away and the hijacker's somehow figured out my frequency and his transmitter is slightly closer than mine so he gets control and I don't. Then he somehow trimmed out my beat up ez* and somehow knew the perfect trim settings for my 180degree pan and tilt that took me a while to program on my 9c. You think I wouldn't see my fpv airplane land by someone's house with full gps coordinates? I would report them straight to the police, and chances are its someone I already know from the forums. I'm trying to understand your logic but I just can't accept how you thought this through .

  8. #18
    Test pilot addict airtruksrus's Avatar
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    I may have put the DX6i to the test by flying around the small park fliers and blade cp with a 2.4Ghz cam and Vtx combo and probably flew around 10 hours worth of flying and only had it lockup once. The video range was limited to 400 ft but good enough to start out basic fpv. It was probably the speed control sucking up all the battery, who knows. It was a foam plane, bounced on the lawn didn't really break much.
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  9. #19
    Navigator Airborne's Avatar
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    Perhaps "encryption" or "transmitter authentication" would have worked better.

    72MHz was the standard for control right up until processing power and component costs reached the point where it was economically feasible to change said standard, pretty much "because the old standard sucked".

    Everybody says get a 72MHz radio, without saying a word about all the problems that drove people to not use 72MHz in the first place. If it's all gravy why did everyone switch? (Old farts don't count, they still fly nitro and have VCRs flashing 12:00)

    "It's not possible because no one does it" does not equal "it's not possible". I gave you the wackiest, most implausible scenario I could think of on purpose. Any way you look at it, if someone turns on another radio on your channel, it's not going to have a happy ending.

    There's already one thread about a guy reporting cloud flights to the FAA because he wants to be the FPV police, how long do you think it will be until someone starts jamming them "for the lulz"?

  10. #20
    Test pilot addict airtruksrus's Avatar
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    Still using 72 Mhz in a limited fashion, the Vtx was causing the camera pan servo to glitch full deflection every 20 to 30 seconds. Out of 20 + years of use, been shot down atleast 3 times.

    The channels at my field are more open than they used to be when 2.4 came about.
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