Independent tests prove lack of frequency hopping with XPS

[Woketman]

huh???

[BaldEagel]

	Quote: Originally Posted by bodywerks
	kill this thread already!!!

Its not the thread that needs killing, its the string about the frog, lets get back to the real content of the Thread, the frog thing even though it was funny detracts from the purpose of this Thread.

Mike

[phippsj]

OK. My XPS system finally flipped out. I have a 2.3M Comp-Arf that I have not yet converted from XPS to my new JR X9303 system. Since I have not had one issue with the XPS system for over a year, and this was a plane I rarely fly, I wasn't in a big hurry to convert it over.

On my second flight yesterday, the plane went into failsafe as I was in a down-line and starting to pull out and add throttle. Nothing moved and the engine didn't rev up. I had set my failsafe long ago with power at idle and neutral surfaces. Luckily, I was still up high and regained radio control in time, but then it went into failsafe again and again about every 10 seconds. It was another minute of thrills before I was able to limp it around and plop it down on the runway. At one point, I was considering flying it away and dumping it in a field.

This was my first experience with a plane going into failsafe while flying, and it was not fun. I feel lucky that I got the plane back in one piece and nobody was hurt. Of course, back on the ground, I couldn't replicate the failsafe lockout. I swore then that the XPS equipment was going into the garbage.

That night, back at home, I pulled out the XPS receiver and put in the JR 2.4 receiver. I've decided to hang onto the XPS module and two receivers for now, just waiting for the class-action lawsuit to be announced.

I was skeptical about the claims of XPS lockout, but not anymore. Keep this thread alive so others may be warned!

[XJet]

	Quote: Originally Posted by phippsj
	I was skeptical about the claims of XPS lockout, but not anymore. Keep this thread alive so others may be warned!

Your experiences highlight the very worrying aspect of a 2.4GHz system that has no redundancy or agility.

It'll work just fine (hence the XPS FBs who claim everyone else is lying about the system's deficiencies) right up to the point that some strong interference appears on the part of the band it's using.

Once that happens, there's nothing it can do except go into failsafe.

Under the same circumstances FASST will continue to utilize those parts of the band that are still noise-free and Spektrum will fall back to its alternative frequencies.

From a personal perspective I've got no issues with people buying and using whatever they want but what does really annoy me is when people who know very little about this technology (or think they know more than they do) go around telling others that "there is no problem" and that "XPS is perfectly safe to use on any model" -- when the reality is far from this.

Virtually all 2.4GHz systems have had issues but only XPS refuse to acknowledge any weaknesses in the design or implementation of their system.

That *is* a worry.

[zoomer260]

My my.The thread lives ! There is a guy at my field that is flying XPS in his 40%. I witnessed one lockout and a smaller plane trashed for unknown reasons. Personally I wish he would change to something else before I see his 40% becomes an offering to the gravity God. He's a good guy and I'd hate to help pick up the pieces.

BUT. I lost my first gasser to PCM lockout. Flew the same channel PPM before and after with no issues. I fly PPM today.

[XJet]

Guess what?

XPS has announced that it will have a firmware update (as of the end of the month) that provides full-time frequency hopping for their systems.

This must come as a surprise to those who honestly believed that XPS already hopped.

It's also even more of a surprise when you consider that the hopping tactic they claimed for XPS (only hop when necessary) would actually be superior to a full FHSS -- if it actually worked (which it doesn't).

You see, by going to FHSS, this guarantees that *any* strong noise on the band will be encountered during normal use and thus add some degree of latency to control response. Unless the band is very noisy, that latency will go unnoticed on a good FHSS system but it is the one disadvantage of full-time hopping systems.

So, if XPS are to be believed, they have *downgraded* their system from a "hop on demand" system to FHSS. Why?

It's also worth noting that in Europe, Graupner (the XPS/IFS distributor) is offering this "upgrade" free of charge.

Elsewhere in the world there's a $30 charge.

Why the difference?

Perhaps because Graupner are already hurting bad from the bad-press that the numerous crashes attributed to IFS/XPS have created and they're hoping that this upgrade will restore some of the badly trashed reputation the system has. Perhaps it's also because consumer law in Europe is far stronger than in the USA and they know that the cost of the upgrade is a whole lot less than the cost of a refund for all those customers.

But here's another strange thing...

Lots of XPS customers purchased the XDP because they were told it would allow them to upgrade their own systems to new firmware using downloaded updates from the Net.

Well let's see -- since XDP was released there have now been two firmware updates. One for the near-useless telemetry and now one for the hopping. And guess what? Both have been "return to base" updates. The XDP seems to have been unable to perform one of the key claims made for it.

But good on XPS for *finally* acknowledging the massive flaw in their system and the bogus nature of their previous claims (I wonder if they'll apologize to those who tried to ring the alarm-bells along the way and found themselves slandered and attacked for their efforts? -- I won't hold my breath).

Of course the question is now: is this just too little too late to save XPS?

Companies like Jeti appear to be delivering *right now* the stuff that XPS has been promising for over a year. A solid RF link, telemetry that is *useful*, end-pin receivers, downloadable software updates, etc, etc.

XPS has proven themselves to be untrustworthy (refusing to acknowledge *any* flaws in their system and maligning those who try to inform others as to the real facts) and clearly not the "smart cookies" they claim to be.

They are no longer the only player in the field with the bottom-end being nicely filled by the likes of Assan, Corona, iMax, etc with Futaba/JR at the top and new entrants such as Jeti and Weatronics poised to establish their own niches.

It would appear that XPS customers must enjoy being treated like mushrooms.

If you're an XPS customer living outside Europe, I suggest that instead of forking out the $30 to have your system "upgraded" to FHSS, you simply place it on the sidewalk and hit it with a hammer.

Why?

Well XPS offer a lifetime crash-damage warranty and as of the end of the month, all systems will be shipping with the new FHSS firmware. By smashing your system and returning it for *free* replacement under the terms of the crash-warranty, you'll save yourself $30.

I sure hope JD has factored this tactic into the costs of implementing this upgrade -- or will we see that lifetime guarantee silently pulled?

[sweetpea]

While I don't agree with you on all your points......

That last one should work. Unethical, but it would work

[Wojcigitty]

XPS support shenanigans aside, what do you think of the viability of the XPS on FHSS now, XJet? Could it work?

[XJet]

*IF* XPS *now* works as advertised (and remember there's not a good track record from them in this area) then it could be a perfectly adequate system.

However, satellite receivers have been promised before (for delivery by June 30) and we have no details on key aspects of the FHSS algorithms being used.

For example, how often does it hop? Is it every 2mS or every 20 seconds? You can't tell from the information published on the XPS website and they're not telling.

If it hops too slowly then the benefits of FHSS are lost and all you get are the downsides.

If it's not a psuedo-random hopping sequence then you run into issues with "tracking" of multiple systems that may be hopping in concert and therefore raising the noise floor that each sees.

Then there's the satellite receiver situation. Even when promising satellites, JD has repeatedly stated that their purpose is not to provide diversity (so what *are* the satellites for then???).

I'd like to think that (probably due mainly to Graupner's influence) XPS has turned a corner and is now delivering on their promises rather than just treating customers like mushrooms - but only time (and testing) will tell.

Obviously they've had to reflash the XBeePro firmware to change the reliable-protocol handshaking to provide a more deterministic communications link and thus allow FHSS but it's been my experience that those who believe they are infallible (aka JD) inevitably produce systems that need *very* serious testing before you use them (for obvious reasons).

Unfortunately I think that the damage done to the XPS brand by all the deceit and denials and broken promises perpetrated to date will never be undone.

Although I'm sure some won't believe it, I await the release of V3 with an open mind.

[tadawson]

You think it's an XBee reflash, or perhaps a totally different RF deck? After all, they were working with some different hardware for the 900MHz system, and might have found it easier to make a change . . . at any rate, it will be interesting to see when it comes out.

- Tim

[XJet]

	Quote: Originally Posted by tadawson
	You think it's an XBee reflash, or perhaps a totally different RF deck?

I'd say a reflash -- replacing the whole RF module would be uneconomic -- desoldering/resoldering and the costs involved would be prohibitive.

The XBee has its own onboard processor and a pretty standard 2.4GHz chipset so it could be reprogrammed for the required behaviour by reflashing.

	Quote:
	it will be interesting to see when it comes out.

Agreed!

[Davkhy]

Check out XPS web site. New continuous hopping system. Version 3.0 available at end of October 2008