Independent tests prove lack of frequency hopping with XPS

[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

[XJet]

Well I'm hoping I'll have a chance to finish off my test gear this week -- since I won't be flying -- some idiot drove over my transmitter today and totally destroyed it :-(

They'll pay for it but it'll probably be $20 a week which means the wife will scoop it out of my wallet and use it on frivolous things like the electricity and phone bills :-(

[ricoalonso]

	Quote: Originally Posted by XJet
	Well I'm hoping I'll have a chance to finish off my test gear this week -- since I won't be flying -- some idiot drove over my transmitter today and totally destroyed it :-( They'll pay for it but it'll probably be $20 a week which means the wife will scoop it out of my wallet and use it on frivolous things like the electricity and phone bills :-(

Are you serious? Did you check if he is an XPS fan? Ok, that was a joke! But seriously, sorry to learn that. That's why I'm always hesitant to lay my Tx on the ground... so afraid someone might step on it.

^R^

[Flatlandman]

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

I never said that it does hop but i will tell you that im pretty sure it will and does but i dont know when it hops or if it hops enough to make a difference. I hope we get some data that tells us when it does hop and i hope we can determine if its useful or not.

[BZFrank]

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

Thanks. That 'video' proof looks a bit inconclusive to me - it only shows that XPS did not go into failsafe after some tries, not that control is maintained. This is consistent with some 'lockout' reports which report that while the link was down, the system did not get into failsafe. I suggest to repeat that test with a frequency analyzer running in parallel. Xjet - could you add this to your test cases if possible? Also it took how many tries to achieve this result?

I don't think that any hopping scheme that only works 'sometimes' to 'almost never' in the face of interference meets my personal criteria of a dependable RC control.

Frank

[DesertHucker]

	Quote: Originally Posted by XJet
	Well I'm hoping I'll have a chance to finish off my test gear this week -- since I won't be flying -- some idiot drove over my transmitter today and totally destroyed it :-( They'll pay for it but it'll probably be $20 a week which means the wife will scoop it out of my wallet and use it on frivolous things like the electricity and phone bills :-(

Sorry XJet don't have a TX to send you, hope it did not have the XPS module in it!

Bad luck hope you get it sorted and back in the air.

[XJet]

Strangely enough, it didn't have an XPS module in it at the time -- but come to think of it, I don't think that would have helped -- it wouldn't have hopped out of the way of the oncoming vehicle anyway:-)

It's not my only transmitter -- but I did have a few regularly-flown models programmed into it and it was half of the club's buddy-box setup so there won't be any training going on around here until it's replaced.