Independent tests prove lack of frequency hopping with XPS

[KrisW]

"It's so much faster and responsive.. I can FEEL the difference ! ! !"

Ahem. . Slick Marketing at it's best.

[3DDevil]

Xjet,

I have to disagree with you on the 'responsivness' feel factor of the XPS. In the end its one of the only things I miss from it... I can tell you I definately noticed the plane was way more responsive. My low rates became like my high and my high became ultra high. I cannot tell you why, but I know what I felt. Other guys at my club found the same thing with XPS. One guy was even flying an old warbird as a test bed and he even found this plane to be more responsive and twitchy.

I was using a JR 9XV2 with PCM RS77S Rx before the XPS. I then used the XPS module and 8Ch Rx. I changed nothing in the plane settings on the radio before I first flew with XPS and beleive me it was way more touchy and needed to be tuned down in the radio for the second flight. As I said. I dont know why, but I know what I felt. I also learnt what I didnt feel.... and that was a response to stick input, just before the Extra hit the ground, destroyed itself and became another XPS statistic!!...

[MalaysianFlyer]

	Quote: Originally Posted by KrisW
	"It's so much faster and responsive.. I can FEEL the difference ! ! !" Ahem. . Slick Marketing at it's best.

I had one 14MZ owner come up to me and start going on and on about how fast the response was on the radio with G3 PCM, and how it was faster even when set back to the old PCM1024 mode (god only knows how he figured that), and kept insisting that it was faster when I disagreed. He finally shut up when he realised that I was using an FX-40 and decides to exit with what dignity he has left, then he comes back 5 mins later and starts telling me about latency test results that someone had emailed to all the local flyers that shows how fast the 14MZ is compared to other radios. (He did not realise that the person who had emailed the latency test out to the local flyers was actually ME!!!! )

So, I just told him that it must be great to have 200ms latency and can you please show me your hands on the sticks moving to five discrete positions in one second, to enjoy this speed LOL

Strangely enough he doesnt talk to me anymore LOL (thank god)

Every radio manufacturer be it JR FUTABA XPS SPECTRUM XYZ DEF ABC and CR*P will always have to claim there is something that makes it worthwhile for us to spend $$$$ and more $$$$ hence the "faster response time ploy" "increased resolution ploy" etc etc

Interestingly enough, one of the test on RCgroups showed a 10yr old Airtronics stylus as having a lower latency than a 14MZ OWWWW my FX-40 is now a piece of crap as it cant beat a 10yr old radio!!!!

Sometimes ya just got to laugh..... then go fly and enjoy yourself!!!!

[Julez]

Coming back to the original topic of this thread:
It seems XJet was not fast enough, someone else did the tests before him.
Nevertheless, these tests prove his opinion to be correct:

http://www.rcgroups.com/forums/showthread.php?t=814276

[bob_nj]

Incredible and scary at the same time.

You did just take all the fun out of this thread though

[ricoalonso]

Julez,
I read the thread and what I understood is that even the notion of XPS going to 'frequency hop' if the noise is slowly introduce seems to be not true also??

[jonkoppisch]

..

[Julez]

	Quote: Originally Posted by ricoalonso
	Julez, I read the thread and what I understood is that even the notion of XPS going to 'frequency hop' if the noise is slowly introduce seems to be not true also??

This is the way I understood it as well.

[XJet]

	Quote: Originally Posted by 3DDevil
	Xjet, I have to disagree with you on the 'responsivness' feel factor of the XPS. In the end its one of the only things I miss from it... I can tell you I definately noticed the plane was way more responsive. My low rates became like my high and my high became ultra high.

Did you compare the actual servo throws with the FM setup and the XPS setup?

It *is* possible that XPS is simply delivering greater servo throws per degree of stick movement.

The latency of XPS will always be greater than the latency of a dumb FM/PPM setup, that's a fact, so if you're experiencing greater sensitivity then the XPS is not accurately representing your stick positions.

[XJet]

	Quote: Originally Posted by ricoalonso
	Julez, I read the thread and what I understood is that even the notion of XPS going to 'frequency hop' if the noise is slowly introduce seems to be not true also??

That would appear to be the conclusion reached by the tester - and it does agree with my own informal tests.

I was willing to give JD the benefit of the doubt (due to the unscientific nature of my initial testing) but it seems that the entire frequency hopping abilities of the XPS are now in doubt.

If this is the case, it certainly puts XPS well behind Spektrum/JR and Futaba in terms of the resilience and robustness of its radio-link.

Those folks who are happy to place their giant-scale planes and the lives of bystanders in the hands of a system that (it would appear) can be shot down by interference on a single part of the 2.4GHz band are free to do so but it's not something I would do.

True, it's no worse than 72MHz -- but it's no better either. XPS remains a viable 2.4GHz option, but certainly not the best one when you're flying expensive and/or dangerous models.

[sweetpea]

The only thing the test is missing is comparison of FASST and Spektrum on the same test to verify that they are actually more robust and unaffected by the same situation.

Until that is done it is all speculation on our parts.

My opionion is that they will pass...but I'd like it to be 100% proven.

[jonkoppisch]

According to the name of the thread... " Independent tests prove lack of frequency hopping with XPS" I'd say that there's no longer any speculation...

I believe that spektrum would be effected as well but have 2X's the chance to survive over xps unless the entire 2.4 band is swamped then none of them would survive. Futaba is looking like the overall best solution but..