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Old Aug 19, 2011, 05:31 PM
Blueshy is offline
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OSUFPV - KF7VFT
Corvallis, OR
Joined Apr 2010
1,790 Posts
Quote:
Originally Posted by jasmine2501 View Post
But that is just the fact of 2.4GHz systems, having nothing to do with FPV really. And Spek isn't any worse off than anyone else. Some systems hop around, some systems spam the whole band, and some use wide-band channels. As long as your video system isn't on 2.4GHz, all of these methods should suffer equally in the presence of your video transmitter. IBCrazy just pointed out a few posts back that the harmonics DON'T interfere, and I'm not sure why people keep saying that.

There's a video on my channel which shows a Spek system competing with a "deliberate" wide-band jammer. What's interesting is this - with the jammer turned on, you can still see the Spek signal, but the Futaba signal fades into the background (it is equally jammed everywhere it tries to go). I've seen this on a spectrum analysis - so don't tell me Spek is worse in the presence of a jammer - it's not.
Yes, Spectrum DSM2 IS worse off than other systems that use FHSS or
other methods. I was just pointing out that DSM2 is of the worst frequency
hopping methods to use around FPV, and really any interference in general.
This is why, after long denying that DSM2 and their others sucks, Spectrum
decided to join the rest of the modern world with DSMX.

And, yes, all stock 2.4ghz pretty much do suffer equally in the presence of a
video transmitter. It doesn't matter what stock 2.4ghz you use there's just
too much power from our VTx's making a large noise floor next to 2.4ghz
receivers. This is why you can either switch to a different frequency (one
that is lower and with an efficient and robust frequency hopping system), or
you can ramp up the 2.4ghz signal to compete with the larger noise floor the
receivers are subject to (add a 1W-2W booster to your stock 2.4ghz
controller).

The problem with that test with the jammer which makes it very misleading is
that its not a problem of jamming but a problem of noise floor. These 2.4ghz
systems were never designed nor intended for the ranges we aspire to go
FPV.
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