Independent tests prove lack of frequency hopping with XPS

[Kiwi]

OK,

I have finally managed to get some results after weeks of computer issues and a wife wondering if I had a new lady in my life at night.

Man what a marathon. But I have a screen capture video of the test on XPS and I jabber on a lot I know, but hopefully its understandable.

It is repeatable, no I was not looking for failsafe or glitches. The test was to make XPS hop.

I did not, it would not and it won't. I actually think it just plain cannot.

Go here for the results as this thread is way too long for others to find this.

http://www.flyinggiants.com/forums/f...tml#post408254

[BaldEagel]

Kiwi

Brilliant stuff, just the sort of information/ammunition we need to get this thing sorted once and for all and all of us, thanks for doing all the hard work.

Mike

[buttface]

Yea I always knew that XPS crap was junk after mine and my buddy's failed .He lost a turbine jet and I almost lost a 40%er!

[Flyfast1]

There's a guy over at RC Groups that has posted a video of the XPS system changing channels in response to interference. He used a 2.4 Gig video transmitter as an interference source. He shows his XPS system going into failsafe and then he has full control, even with the camera still transmitting. It would be even better if he also had a spectrum analyzer or even the XDP to show the channel change. It's interesting.

-Ed. B.

[DadsToysBG]

I watched that video and for the life of me I couldn't make any since out of it. I saw the servos lock out, but I couldn't tell if it hoped or what or even f the servos moved again. I watched it several times. It proves nothing to me. Dennis

[Flatlandman]

This is not knocking Kiwi as a person just a scientist. Im not dis proving his statement or saying his tests are bad just incomplete. He did about 3 test that prove what we already know and then came the blanket statement that xps wont change channels. Its like me getting my sister to shoot 3 free throws with her missing those 3 and using that info to tell you that she will never make a shot from any range. This is the problem i have with this test and many others. If your gonna say it wont do something you need to have more than what i see that Kiwi has compiled. If Xjet ever tested this i think from reading his previous posts that he would go further and more complete.

[aviti]

OK, say it does hop when you stand on your head with three transmitters aiming at each other and your fingers crossed, who cares? Don't people find the marketing just the slightest bit misleading? Hell, I figured it wasn't frequency hopping when I saw the asterick * by the feature in his advertising.

Do I know enough to understand if a 2.4 system needs to hop or be on 2 channels, nope, not really. But I just figure if JR, Spektrum, Futaba and Airtronics couldn't make a system reliable on just ONE channel, then why can Jim Drew do it?

[Flatlandman]

Your missing the point of that post. Im not trying to defend or stir the pot just posting thoughts on the tests parameters.
XPS said them selfs that a sudden interruption wont cause a jump but that seems to be all the tests are doing that i have seen. The tests should include more ways of intermittent interruption since the purpose is to make it hop. When many many ways have been tried to make the elusive frequency jump happen and no one gets a hop then a fair statement can be made of no hop. But the tests being done are the same 3 repeated so we have a thousand tests that are worth very little in the way of a final statement.

we need some one else to try the fasst test some more times to make it jump to confirm the one test that proved a jump.

or the final say can be we all pass the hat and get the independent tests that xps doesnt want to spring for.

[aviti]

	Quote: Originally Posted by Flatlandman
	Your missing the point of that post. Im not trying to defend or stir the pot just posting thoughts on the tests parameters. XPS said them selfs that a sudden interruption wont cause a jump but that seems to be all the tests are doing that i have seen. The tests should include more ways of intermittent interruption since the purpose is to make it hop. When many many ways have been tried to make the elusive frequency jump happen and no one gets a hop then a fair statement can be made of no hop.

My point is who cares if it CAN hop. If it doesn't hop at the point it is needed then the plane is in the ground. I don't know if it needs to hop or not but with all the controversy surrounding this deal, I'd rather not find out with my plane.

[Flatlandman]

There your assuming a lot IMHO. You dont know if its not hoping "at the point its needed"

[aviti]

	Quote: Originally Posted by Flatlandman
	There your assuming a lot IMHO. You dont know if its not hoping "at the point its needed"

Same assumption on your part that it is hopping.

[tadawson]

	Quote: Originally Posted by aviti
	Same assumption on your part that it is hopping.

Hopping has now been verified at least three times, one on video. All the other tests prove is that none of the testers could create a test scenario that was appropriate to generate a hop, not that it won't. It's kinda like looking for a supposedly lost object - if you find it, you are 100% sure that it exists. If you don't, you don't know much other than it is an even shot that a) it never existed, or b) that you didn't look in the right place . . . never 100% certain!

- Tim

[KrisW]

	Quote: Originally Posted by tadawson
	Hopping has now been verified at least three times, one on video. All the other tests prove is that none of the testers could create a test scenario that was appropriate to generate a hop, not that it won't. It's kinda like looking for a supposedly lost object - if you find it, you are 100% sure that it exists. If you don't, you don't know much other than it is an even shot that a) it never existed, or b) that you didn't look in the right place . . . never 100% certain! - Tim

Sooo. . looking at the entire scenario logically. . . we have three instances of XPS hopping. . . we have many instance of it NOT hopping, and no one seems to be able to MAKE it hop at will, while watching it on a graph or frequency detector. We also have many cases of total loss of control of the aircraft, and the plane then crashing, instead of recovering control through the XPS unit regaining a data link. . again proving that on an all too frequent basis XPS somehow loses link, does not regain it, and the result is a lost aircraft EVERY TIME.

Then we have people who have been flying XPS for hundreds of flights, and never a glitch or problem.

So. . we cannot MAKE it hop when we want to, but sometimes it appears that it will hop when IT wants to, and we have no way of predicting that in the case of interference the XPS will hop when we NEED it to, instead of when IT wants to.

Tthis is like playing Russian Roulette with a 100 chamber cylinder in a pistol. Spin the cylinder and slam it closed. . .start pulling the trigger in a group of 50 people, one at a time. To quote Dirty Harry. ."well Punk. . do you feel lucky??"

Not me, sorry. . . Logically, I can see NO reason, given the information at hand, and the LACK of clear information to the contrary (From XPS) that I should trust XPS to hop when I need it, instead of when IT feels like doing it. So, logically, I should never use the XPS system, since it fails to act as I desire it to EVERY time I NEED it to.

Logically speaking. . XPS is a bad idea.

Mr. Spock would be so proud. . . . .

[BZFrank]

	Quote: Originally Posted by tadawson
	Hopping has now been verified at least three times, one on video. - Tim

Can you point me to the video please?

[ricoalonso]

While it is true that another poster at RCG had a video which showed that XPS seemed to have hopped to another channel, after purposedly getting it into multiple failsafe/lockout situation by using a video camera as a noise generator, it is also not clear whether there was total control at the time that the supposedly 'hop' was observed. Some observers of the video thought that there may actually be a total lockout since the servos never moved anymore even when the video camera is taken near or away from the Rx. At the beginning of the video, I saw the Tx far at some corner and it seemed that the poster only made use of the failsafe as an indicator whether the Rx was affected or not by the video noise.

Even if it really hopped... what are the chances that it will be really be useful and be able to save the model if the hop will only occur after a few lockouts? What if one lockout is longer and the model is getting closer to the ground fast?

Anyway, as I said at the RCG forum, I already accepted the fact that XPS hopping algorithm (if ever it really hops) is not much useful and/or applicable to normal noise situation at some flying fields. I guess the only thing to watch now is how XPS will react. I really think that their future actions and how fast they react to these situations will show how serious they are in supporting and improving their product.

^R^

Edit: BTW, here the link http://www.rcgroups.com/forums/showt...816984&page=36 check post #535