Independent tests prove lack of frequency hopping with XPS

[Pale Rider]

Agreed--Like I said electric stuff is prolly a whole different ballgame and as you stated, its pretty well known about the voltage requirements. Not sure about the other Spektrum radios, but in my 9303 there is at least a warning now about it.

[brn2fly]

	Quote: Originally Posted by BoneDoc
	Who is to say that continuous hopping is optimal? What if the next two channel FASST hops on to is jammed? How dies it know where else to hop to?

It hops 500 times a second so jamming should not be an issue. Heck the military use a secure radio system that frequence hops too.

[sweetpea]

But anyone in the military will tell you that it isn't that reliable as far as getting your code to match everyone else so you can talk. (at least the version on my plane)

[brn2fly]

	Quote: Originally Posted by sweetpea
	But anyone in the military will tell you that it isn't that reliable as far as getting your code to match everyone else so you can talk. (at least the version on my plane)

If it's set up correctly it works fine, just a lot of stuff to get it working, BTW I PM you earlier. Looks like I will in Vegas Saturday and Sunday. What hobby shops are there here that deal with giant scale stuff.

[sweetpea]

Didn't see the PM......sending one back now

[XJet]

	Quote: Originally Posted by sweetpea
	So in a nutshell you have the companies learning from each other I'm very sure....... XPS...... Freq does not hop with sudden increase in noise floor past a certain threshold. --XPS states that this was because a sudden increase would typically cover the entire band so they software limited it not to hop

This is where JD and I differ in our opinions.

I've spent a *lot* of time looking at the 2.4GHz spectrum from an aerial perspective and I've seen far more instances of relatively narrow-band intense noise events than I have of all-encompassing noise sources.

Although JD says he's spent time analyzing the 2.4GHz spectrum, I think the experience that lead to the retrofitting of transmitter modules with an external dipole indicates that perhaps he's only done so from ground level -- and there's a *huge* difference. Unfortunately, it's in the air that things really matter most so ground-level observations (amidst the shielding effect of ground-clutter) are likely to have given him a bum-steer in this regard.

	Quote:
	--XPS has a software fix for this coming soon so it will hop no matter what

I certainly hope that "coming soon" in this case is a little faster than it has been for those 6-channel receivers and telemetry. :-) Let's hope that JD prioritizes this for the sake of his customers. I also wonder if the solution will be compromised because he doesn't want the hassle of having to "tens of thousands" of the XBeePro modules re-flashed -- at his own expense.

I wonder if this will be pitched as a "feature upgrade" that will carry a fee of some kind.

	Quote:
	--No independant testing has been done on gradual increase to date to verify it hops

Stay tuned :-)

Since I've now been offered a Spektrum and a FASST system to test, I'm in the process of working out how I can create a suitable test environment to put them all on trial. By subjecting them all to the same conditions, it should become very apparent which is most able to cope with a range of different scenarios in respect to noise-levels, interference, swamping, multi-pathing, etc.

	Quote:
	Spektrum......battery voltage issue... FASST...couple of lockouts I've read about but not much else... ASSAN and the other 2.4 companies....to new and not much reporting going on. They also... 72mhz....prone to all sorts of interference and the dreaded shootdowns. But a viable solution...

Today I had a few spare minutes so I threw a new set of (yet another, hitherto unknown) Chinese-made 2.4GHz RC gear into my Katana P profile. It was a very hasty install without much regard for the orientation and spacing of the receiver and satellite antennas (so hardly a really fair test), especially since it only attained a ground-range of 250 yards.

I flew the model and it was *very* loose with very noticeable latency on numerous occasions. What's more, it was the first time I've *ever* experienced glitching on 2.4GHz. Tomorrow I hope to get a chance to re-install the gear with a little more care and thus get a more realistic indication of how it is capable of truly performing.

This gear certainly is very cheap, I'm only hoping that it's not too "cheap".

Full details to follow.

[exeter_acres]

	Quote: Originally Posted by XJet
	Full details to follow.

[Dizzane]

My question is why would anyone even look at the XPS system? Hum... trust your plane to some guy, that doesn't have a good background, or JR and Futaba that have been doing this for years? I guess for me the XPS system never did make sense to me. It looks as if this guy is doing all his testing on his customers.

[RadiMani]

Is Graupner's IFS completely same system as XPS? Or is any improvement inplemented for Graupner IFS? If not, why Graupner adopt XPS? Big question...

[Leseirf]

	Quote: Originally Posted by RadiMani
	Is Graupner's IFS completely same system as XPS? Or is any improvement inplemented for Graupner IFS? If not, why Graupner adopt XPS? Big question...

IFS is rebadged XPS. Only difference is a change in the default country code.

	Quote:
	My question is why would anyone even look at the XPS system? Hum... trust your plane to some guy, that doesn't have a good background, or JR and Futaba that have been doing this for years? I guess for me the XPS system never did make sense to me. It looks as if this guy is doing all his testing on his customers.

As a satisfied XPS user I'm following this thread closely. Lots of good info and potential to cause improvents to the system. Posts like this threaten to turn it into a typical XPS bash. I really hope that doesn't happen.

Mike

[Julez]

	Quote: Originally Posted by brn2fly
	It hops 500 times a second so jamming should not be an issue. Heck the military use a secure radio system that frequence hops too.

No, it does not. At least not according to the tests I did.
http://www.rcgroups.com/forums/showt...49#post8099349

But 125 hops per second are not too bad, either

Cheers,

Julez

[Frosty 4]

Any new technology is paid for by those that have to have the latest thing. 2.4 is still evolving and probably will for a few years. The nanowire batteries will be another item that will evolve. The way things are going 72mhz will die off once the FCC sees the swing to 2.4ghz. Or cut the number of channels .Some LHS don't even stock 72 systems any more.
F4