Kiwi's XPS test results are up.

[XJet]

	Quote: Originally Posted by Daemon
	Around here, they suck. All of them. Pre-CC ,post-CC, every model, Berg 4, 5, 6, 7. They lag, they glitch, they fly out of range at 100 yards and fall from the sky. I *literally* don't trust them any further than I can throw them, and several times, visiting pilots have come to our slopes or fields and had planes glitch, lock-out badly in the air, or crash outright, and we've discovered that they're using a Berg, again, both old and new models. ian

It sounds as if you've got a lot of noise on the image frequency around where you fly -- which is something that *all* SC receivers have trouble dealing with.

I'm not actually that impressed with the way that Peter Berg tried to downplay the importance of dual conversion in RC receivers. The Berg receivers are designed on the premise that the DSP will take care of any signal that gets through on the image frequency -- but this only has a very small chance of success.

[XJet]

	Quote: Originally Posted by RichardCorby
	I as well noticed the difference when I went to XPS. I'm not a world class flyer, so use a lot of Expo to keep me from overcontrolling. With the Futaba 9c and Fm RX, I had the Expo set to 60 %, after using XPS, I was overcontrolling again, so on one particular plane that I fly most, I went to 80% to get back to where I didn't have so much problem with it.

A couple of things...

80% is a *LOT* of expo! Are you sure your throws didn't increase when you switched to XPS?

Did you actually check to see if the throws were different when you switched systems?

The plane won't know what RC gear is being used and if a control surface is deflected by x degrees then the resulting response will be the same. If the control input acts a little more quickly due to reduced latency then it'll also respond more quickly when you remove the control input so overcontrolling shouldn't be an issue.

Remember also that we're talking about 10ms or so of reduction in latency over a PCM setup. With most servos being around the 0.15 second mark for 45 degrees deflection (0.3 deg/mS), which means even if you peg the stick, the control surfaces on an XPS system are only going to be 3 degrees or so ahead of the standard system in terms of servo movement.

Enough to make a real difference? I don't know.

If it's just reduced latency (which I doubt) then all you've got to do is fly a while until your brain adapts to the more immediate response.

If the latency is reduced then your plane should be *easier* to fly (after retraining your brain) because the control surface deflections will more accurately follow your finger movements.

I always found it a *lot* harder going from low-latency to hi-latency setups than the other way.

Adding expo *won't* change the speed at which your servos react to stick movement and 80% is a wicked-high amount of expo on any plane.

On my 3D profiles I have 55% expo and that's with huge surfaces with over 50 degrees of throw either side of neutral and I have no issues with it being too touchy or oversensitive in straight and level flight.

Even my 30% Extra 330L gasser has just 55% expo on elevators and ailerons and it's set up for 3D throws as well. I don't use dual rates (just another switch to flick (or not flick) at the wrong moment) -- I just learn to move the sticks a little less aggressively when flying on the wing.

This is probably the subject for another thread but how much expo are others using?

[bob_nj]

Subscribing to the volumes of information hoping to eventually digest

[uninverted]

Not the place I know.
If that much expo is being used, maybe a look at the link positions on the servo/horns should be looked at.
In on servos, out on horns, all about mechanical advantage. Works for me. Reduces throws, but if overcontrolling who needs wild throws.

[Daemon]

	Quote: Originally Posted by XJet
	It sounds as if you've got a lot of noise on the image frequency around where you fly -- which is something that *all* SC receivers have trouble dealing with. I'm not actually that impressed with the way that Peter Berg tried to downplay the importance of dual conversion in RC receivers. The Berg receivers are designed on the premise that the DSP will take care of any signal that gets through on the image frequency -- but this only has a very small chance of success.

Agreed 100% on both points. Any time the issue comes up, everyone quotes Peter's article
on the subject, and I think it's a fundamentally flawed premise. That said, some SC PCM
Rxs work just fine here.

ian

[tadawson]

	Quote: Originally Posted by Daemon
	Agreed 100% on both points. Any time the issue comes up, everyone quotes Peter's article on the subject, and I think it's a fundamentally flawed premise. That said, some SC PCM Rxs work just fine here. ian

Hmmm . . .

I run older Bergs in all my electrics - planes and helis, and they are the **only** thing I have found that will run clean in the helis, short of PCM . . . . but never a glitch in a one of them, and response feels fine to me . . .

I guess we all see things differently . . . .

[Foamaholic]

I had 15 Bergs for a few years until I went 2.4. I remember only one minor glitch.

[Daemon]

Just remember this conversation when dissing a particular 2.4Ghz system or whatever.
I've seen more people hike to recover plane or pieces of plane due to flying Bergs than any other
Rx, ( 72Mhz, 6m, 2.4Ghz.. you name it). Illustrates a point I've made here before.
Just because one person has had all good experiences so far, does not invalidate the
fact that someone else has had some or all bad experiences, nor prove that the technology
is all good, or all bad. It has to be put in the proper context.

ian

[4*60]

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[XJet]

	Quote: Originally Posted by 4*60
	Found a big difference myself when I went to XPS. Control smoother, better control, more responsive. Control throws/deflection seemed to be identical to the original with Hitec RXs. I flew on changeover, with just the above difference in feel noted.

Were you flying FM or PCM before?

What receivers were you using?

[Gordito Volador]

Kiwi,

Thanks for all of the effort that you have put into this project. I will be taking my WiSpy 3.0 to a big electric (SEFF) event in Early May and hope to capture what is happening with the band saturated with many 2.4 systems by different manufacturers running at the same time. I'll be sure to share it with you.

Regards, Bill

[Kiwi]

Bill,

That will be great to see and I will have my setup at the Nall this year to do the same. They have made it even better by having the 3D field purely 2.4 Ghz so I hope to get some really good information from that event as well.