Kiwi's XPS test results are up.

[jonkoppisch]

They're even wiping out on water now...

	Quote: Originally Posted by dasrennboot
	I am a racing boat modeller from Germany and using the IFS Graupner System with MX-22 with XR-16 IFS receiver since March 2008. During the last championship race (April 2008) my system go into fail safe but the 1 second minimum possible fail safe time was to long to prevent a full speed crash with the quay wall. My request to Graupner was to minimize the possible fail safe time to JR "standard" 0,25 sec or less. Is there any update available to have this possibility in the "near" future. I change the system back to 40Mhz SPCM because I run my boats during approx. 20 years without any big "impact" like the above described. Fore sure, the problem which caused fail safe, I have also to investigate, but due to the speed of our boats, approx. 80km/h, 1 second fail safe response time is still to long and means approx. 25m movement without control before throttle goes to idle. Any update from JimDrew will be appreciated. Regards Stefan

http://www.rcgroups.com/forums/showthread.php?t=871567

[tadawson]

	Quote: Originally Posted by XJet
	(although I hope you're not suggesting that Kiwi has doctored his vids).

Definitely not, but despite that, just because something is on video does not (at least to me) give it any more credibility than a verbal (or typed) description of an event - short of being there in person and being allowed to audit the test, none of these means of communication are guaranteed to be accurate.

- Tim

[adjonym]

	Quote: Originally Posted by tadawson
	Definitely not, but despite that, just because something is on video does not (at least to me) give it any more credibility than a verbal (or typed) description of an event - short of being there in person and being allowed to audit the test, none of these means of communication are guaranteed to be accurate. - Tim

The fact that Kiwi reports not only the results, but the way the results are given,and with what equipment(eg; reproducable results), i'd say the credibility is pretty high. I dare to say that it's a tad higher then the vendor who's only evidence so far is "we know it works".

[XJet]

Yes, JD was a long-time coming with the exact parameters that will cause XPS to hop -- and once he delivered we could see why.

Once backed into a corner and effectively forced to divulge the hopping parameters, he then had to admit that hopping wasn't there to dodge interference, simply to extend maximum range.

It's no wonder he didn't disclose this earlier because it conclusively proves that one of the main claims for XPS was just hype. Yet the FBs still say "yes it'll hop around interference" -- even though independent tests prove otherwise and JD (finally) agrees it won't.

[spoiler]

	Quote: Originally Posted by tadawson
	Definitely not, but despite that, just because something is on video does not (at least to me) give it any more credibility than a verbal (or typed) description of an event - short of being there in person and being allowed to audit the test, none of these means of communication are guaranteed to be accurate. - Tim

For me its quite simple - if you look at the overall, "bigger picture" or context if you prefer, its quite clear to me who is full of BS and who isn't. It seems very strange to me that people continue to defend the indefensible. Even if we dismiss Kiwi's tests as flawed, biased or unscientific, we are still left with XPS's owm admission that their system does not do what they advertised it could do. Why the admission? Perhaps because JD could not avoid the truth of tests by the likes of Xjet and Kiwi, among others.

Its quite clear to me why those claims were made - to convince a RC consumer public, unsure of 2.4 technology, that their system was as good if not better than the other 1st tier contenders. $$$ in other words. So, if people still support XPS/JD , then it seems to me they have a very skewed view of reality. On the one hand, they are prepared to contest credible contrubutors test results, bona fides and logical arguments but seem blind to a bucket full of BS and disinformation from XPS even when the main man there admits that his initial claims for channel hopping were nonsense. I predict a win in the consumer courts against both Graupner and XPS. This has been better than any soapy so far

[Kiwi]

Wow;

I'm flattered that I am smart enough to doctor a video. Perhaps the mistake I made was not to leave the time code running in the window as those videos were uncut, there was no smoke and mirrors. If you look closely at them you can see no fades, no wipes, no background music. That was 100% real time live.

What you dont see is how many times I done them until I got one with no cuss words in it. Thats because I covered the servo with my hands or the radio and you could not see the things I wanted to show. It s also the reason I wanted the scanner screen on a separate laptop. That way it all happened together, no magic, no tricks, no cut and paste and I know plenty of tricks because video is one of my other hobbies.

One thing I was able to do but did not and will not post is video of the XPS in the zombie state. Its not a repeatable test, it just does it sometimes and as the basis for the thread was XPS does not hop I chose to leave that out. Why muddy the water.

Yes I could probably do it all again but I sent the Tx and Rx modules back to the guys who loaned them to me, plus I have my 3M YAK on the slab going together this winter and I'm not wasting another ounce of time testing a system that is faulty, that does not function as advertised and it is a plain waste of my time and your intelligence to push further. The official complaints in Sweden and the USA will show if my testing had merit or not.

If I'm proven wrong then so be it but I do know that FASST and SPEKTRUM work in a certain repeatable environment that XPS does not. Thats enough proof for me. I would much rather use ASSAN who have been seriously honest, very easy to work with and will bend over backwards to make their product better.

I hope someone can keep us informed with progress in these court applications. Times will be interesting.

[tadawson]

	Quote: Originally Posted by Kiwi
	Wow; I'm flattered that I am smart enough to doctor a video. Perhaps the mistake I made was not to leave the time code running in the window as those videos were uncut, there was no smoke and mirrors. If you look closely at them you can see no fades, no wipes, no background music. That was 100% real time live.

If you are referring to my comments, I quite clearly did not say or imply that you did. I just stated that since video is an editable medium, it does not carry the same credibility as seeing something in person, and (at least to me) it does not carry any more credibility than a written report.

For what it is worth, I think that all the tests that I have seen/heard/read about have been accurate and honest - both yours and the guys at Boeing. The big question is what was different that can explain the disparate results? That is what has not been documented.

Myself, I would have liked to have seen field strength comparisons of the XPS and interference signal to see how hard it was being hit, but that's the communications geek in me talking . . . and that would also address my concern that the test in question may have been swamping the XPS RX front end, since everything was pretty close to it . . .

- Tim

[jonkoppisch]

& another one.. It's funny, with their system they don't recommend anything but nihm's or nicads & no switches... Of course, they've never heard of this happening before (in the quote...)

	Quote: Originally Posted by HUNTERNFLA
	OK I BOUGHT INTO THE XPS THING i got a mod for the 9c and 2 recivers after the maidin i almost lost the plane and the 2nd worked fine ive waited untill i recived my money back before posting this the system looks nice but dident work good at all here are the letters i sent to them and there repleys to the questions judge for your self , > I BOUGHT THE 9C SET UP AND 2 RECIVERS > WE FLEW THE PLANES TODAY AND BOTH ARE EXTRAS WITH GAS MOTORS 50 CC > ONE FLEW NO ISSUES THE 2ND ONE WHEN ON APPROCH I HAD IT IDLE UP ( > FAILSAFE??) WE DULACTED THIS 4 TIMES THE RECIVER IS IN THE CANOPY IN > BOTH PLANES THE ONE HAVING THE TROUBLE HAS REGULATORS SET AT 6 VOLTS ON > LITH IONS WE CHECKED OVER THE POWER SUPPY AND RUNNING DUAL SET UP IT > WAS FINE SO WE FLEW IT AGAIN THIS TIME I GOT LOCKED OUT FOR 2-3 SEC > AND WE LANDED BOTH PLANES SET UP THE SAME 1BAD RECIVER?? I WOULD LIKE > TO RETURN IT FOR A NEW ONE I DONT TRUST IT AND WONT FLY WITH IT PLEASE > ADVISE WHAT TO DO HERE THANKS 727-458-4462 You can return the receiver, however, you are more likely having an installation or voltage problem. We don't recommend regulators ever. We recommend using straight Nimh or Nicad batteries, and avoid using switches if possible. Also remember that servo pins are only able to pass a maximum of 5 amps of current, so the entire servo bus can only handle 5 amps. If you are using large digital servos, it is likely that you are exceeding what the input lead to the receiver can provide to the servos. Look at the difference in the power systems between the two planes and see exactly what is different. NO SWITCHES ??? > ok so if i cant use this with this set up there should be a disclamer > on the site im not happy and would like to return it all for a refund > how will i go about it please advise No disclaimer is necessary as this is the case with 72MHz as well. This has nothing to do with 2.4GHz. The problem is more commonly seen with 2.4GHz systems becaus they use computers that require no less than 3.3v to operate. A traditional 72MHz receiver will run down to fractions of a volt. In these cases, the servo speed and torque are non-existant. Did you compare the two power systems used in each plane to determine what differences there are? yes the one has a 6 volt 2700 mah nimh fugi 64 magnito > the other has 2 fromco lith ion with regulators da 50 electronic ign > this is the one that has locked out and went to fail safe 6 times Not surprising really. We see that frequently with Fromeco systems, using our system, Spektrum, FASST, and even 72MHz. If you are going to switch back to 72MHz, we recommend straight batteries - like the one that works. > im just not happy with this and i will be removeing the system and > putting back my 72 i never had any issues with !!! in the past 2 > years please send me the info where to send it for a return > > and you also said that you should not use switches either ?? what The reality is that you should not be using these power systems with ANY radio system. We will forward your request for a return to management. We have never had such a request before, so we are not sure how/if this can be handled. YA RIGHT AS OF 5/29/08 REFUND RECIVED AND VERY HAPPY AGAIN !!!!

http://www.flyinggiants.com/forums/f...tml#post467358

[Pale Rider]

LOL--so they are saying nobody has ever asked them for a refund before ?

[Reckless Loony]

	Quote: Originally Posted by XJet
	Once backed into a corner and effectively forced to divulge the hopping parameters, he then had to admit that hopping wasn't there to dodge interference, simply to extend maximum range.

But even that’s crap.

Attenuation due to frequency and distance is given as

Path loss = 20log(4*Pi*r/w)

Where r = distance, w = wavelength and Pi = 3.141592654

Lets take 2.479Ghz wavelength is 0.1210m then path loss at 400m is 92.4db, which as a ratio is 41,687:1

Now let’s use 2.405Ghz wavelength is 0.1246m then path loss at 400m is 92.1db, which as a ratio is 40,272:1

The difference is 3.5% so if the range were 400m then by dropping frequency to 2.405Ghz you would gain 14m.

Now if you were to drop the frequency to 902Mhz wavelength 0.333m well then path loss at 400m is 83.6db, which as a ratio is 15,136:1, you would gain 175% more range. Of coarse dropping down to 902Mhz also means the antenna would have to grow longer at the same time.

The point is if you want to increase range significantly purely by changing the frequency and not by radiated power or receiver sensitivity then you have to change the frequency by a heck of a lot.

	Quote: Originally Posted by Pale Rider
	LOL--so they are saying nobody has ever asked them for a refund before ?

I am just amazed that Hunternfla managed to get a refund. Last year those 6 dudes in Toulouse France were ignored when they wanted a refund.

[XJet]

	Quote: Originally Posted by Reckless Loony
	But even that’s crap. [snip] The difference is 3.5% so if the range were 400m then by dropping frequency to 2.405Ghz you would gain 14m. The point is if you want to increase range significantly purely by changing the frequency and not by

I'm picking that now his hopping claims have been debunked, he's claiming that when XPS is reaching the limits of range (ie: the retry count starts climbing), the system rescans in case there's an available channel with a lower noise-floor). Hopping to that lower noise-channel will reduce the number of packets lost and thus effectively increase the range (a little). Given is 11-second window this sounds quite likely.

Of course it's a solution to a non-existent problem really. I don't care if my range is increased from (say) 1.5 miles to 1.8 miles thanks to JD's hopping (because I can't see the damned model at that distance anyway)... what I care about is that my 2.4GHz system can avoid the kind of 2.4GHz interference I see on my SA which is usually a very sudden rise in the noise floor over a period of less than a second.

What JD is offering is kind of like your car dealer telling you that "this car doesn't have airbags or seatbelts but it does have automatic headlight washers... what's wrong with that?"

[ricoalonso]

If what I heared is true that someone had filed a complaint at FTC against XPS then maybe that's the reason why XPS is getting soft on their 'no refund' (or sort of) policy.

^R^

[XJet]

	Quote: Originally Posted by tadawson
	For what it is worth, I think that all the tests that I have seen/heard/read about have been accurate and honest - both yours and the guys at Boeing. The big question is what was different that can explain the disparate results? That is what has not been documented.

You're dead right Tim.

Kiwi has fully documented his tests in terms of the parameters and equipment used so they can be reproduced by anyone who wants to -- but we've heard *nothing* about the Boeing tests that would allow anyone else to reproduce them.

So in my book, Kiwi's test have the greatest veracity.

Just as JD said "it hops", we have the guys from Boeing saying "it hops"

But just as JD refused to provide the parameters -- the guys from Boeing have been strangely silent about *how* they got it to hop.

Now disclosing the testing parameters would not expose the Boeing boys to any risk of being sanctioned by their employers (the excuse given to date for not releasing a more formal report) -- so why haven't they.

In my experience of such things, if it smells like a rat, squeaks like rat and refuses to prove it's not a rat -- then it's probably a rat.

And how did Boeing do it?

Well I'm picking they very gradually increased the noise floor (over a period of 11 seconds using a signal within +/- 15MHz of the XBeePro's center-operating frequency). If JD's claims are correct, this *would* produce hopping -- but that's a scenario indicative of flying at the extreme of range and *not* the profile of a typical 2.4GHz interference source.

So the bottom line is this:

JD said XPS would hop so as to avoid potential interference.

Kiwi (and others) tested by subjecting XPS to potential and real interference

It didn't hop.

JD lied.

So JD came back and said "the hopping was never intended to avoid interference, only to extend the range"

So JD admitted that he lied.

But we still have folks saying "Kiw's tests are invalid" and claiming "it does hop"

Unbelievable!

[3ddd]

if the legal actions are aginst jd then a class action lawsuit is next,then we will all get our money back even if jd don't like it.if he was smart he would start giving refunds now and minimize the class action payments

[jonkoppisch]

Yep, he said it again. No mistake. xps does NOT hop if you encounter interference unless it shows up VERY slowly.... So if someone suddenly turns on a device that causes interference to xps it will not hop. You will be locked out!!! It's basically 1/2 of a spektrum system, a single channel unit. NO REDUNDANCY!!!! The was said all along (as when using the live video and xps locked out and didn't hop) and debated.. Now he's finally admitting to it. I can't believe how everyone still defends it...

	Quote:
	JimDrew Xtreme Power Systems Join Date: Jun 2005 Location: Lake Havasu, AZ Posts: 4,415 The hopping is predictive in nature and increases the range of the system by moving to a cleaner frequency. A switch requires 512 frames of a rising (yet varying) noise floor that is +/-15MHz from the center frequency in use. As we have stated previously, a sudden increase in the noise floor (or frequency in use) will deliberately not change frequencies. This was not by accident as in the real world, if the frequency in use becomes fully saturated, the entire band is also saturated. Since the FCC has changed its position on Hybrid type devices, we will now be able to offer hopping on saturation, and even full time frequency hopping schemes by making just a firmware change.

http://www.rcgroups.com/forums/showthread.php?t=872879

Quite a bit different than...

	Quote:
	"Old Oct 10, 2006, 08:09 PM ... · #714 JimDrew Xtreme Power Systems ....... Quote: Originally Posted by pmackenzie I did a quick search, and didn't find an answer from Jim: Does this system channel hop? The Spektrum doesn't, so it is still vulnerable to outside interference. Pat MacKenzie Yes... but not like one might think. Our proprietary system uses intelligent frequency hopping. The aircraft always monitors outside interference, as does the transmitter. When either of them have a problem that can be solved by switching to another frequency, they will do it on the fly. Total time to scan and switch is just under 1ms. If there are no problems with the ambient noise level associated with the communication frequency, then it is not changed."

	Quote:
	"Oct 20, 2006, 02:04 AM ... · #949 JimDrew Xtreme Power Systems Site Sponsor ... .... FHSS hops across the entire band, potentially using every one of the frequencies in the 2.400-2.485GHz band. The Spektrum only uses two frequencies (which it apparently selects based on the current noise ratio at power-up). Our system does not move frequencies until it is necessary but that could be hundreds of times per second (FHSS). We actually have a DSIFHSS system. The Spektrum system stays on the two power-up frequencies, regardless of what is going on. Our system can change frequencies if it detects a problem at either end of the link. This means that if our system is in a plane flying near a school with 802.11g beaming out on channel 6 through a 14dbi antenna, and that happens to be close enough to the frequency that is currently in use by our system, then our system will switch to a new (less noisey) frequency. Our transmitter might think that everything is fine, but the receiver knows that there is a potential problem and the switch occurs. Total time to switch and confirm is less than 1 millisecond (~860us). I got this idea from several wireless internet cards that do the same thing in laptops when 802.11 becomes congested. As it turns out, this feature was already part of the MaxStream radio technology, so it was easy to implement. Reading more of the information linked to above, it is a bit more clear to me that MaxStream's patents likely include the frequency hopping, as this method uses the best of both worlds and helps to completely eliminate the diversity and multipathing issues."

	Quote:
	Oct 26, 2006, 07:26 PM Report This Post to a Moderator · #1213 JimDrew Xtreme Power Systems [IMG]file:///C:/DOCUME%7E1/admin/LOCALS%7E1/Temp/msohtml1/05/clip_image001.gif[/IMG] Join Date: Jun 2005 Location: Lake Havasu, AZ Posts: 4,105 Quote: Quote: Originally Posted by Mihai Also, trying the system with interference at the transmitter is for people that do not understand that the only interference that matters is at the receiver. You're right, which is why both sides are always checking relative signal strength and noise and hopping channels when a problem is determined.

	Quote:
	Nov 01, 2006, 07:02 AM · #1315 JimDrew Xtreme Power Systems [IMG]file:///C:/DOCUME%7E1/admin/LOCALS%7E1/Temp/msohtml1/07/clip_image001.gif[/IMG] Join Date: Jun 2005 Location: Lake Havasu, AZ Posts: 4,105 I have not done any testing with 2.4GHz video. I will look into that today. We have a black widow system that is suppose to be high power. I think as long as one of the 8 different frequencies are used, and it doesn't drift really bad, there should be no concerns with our system. Since we have the ability to move frequencies (unlike the Spektrum stuff), if someone turns on one of these and it makes the noise floor higher, we jump to a new frequency. As long as the power is not tens of watts, I don't think it can saturate the band enough to cause a total loss of communication where a frequency change could not occur (due to the inability to communicate and execute the frequency change). I just ordered one of these 1000mw transmitters for further testing.