Independent tests prove lack of frequency hopping with XPS

[Kiwi]

Exactly sweetpea.

This is not something to set XPS up to fail. Its a setup to see how they all work.

[50%plane]

	Quote: Originally Posted by Kiwi
	The scanner has arrived, The XPS units have arrived, My transmitter module for the 2.4 Ghz spectrum analyzer has not and without that I cannot do a thing to force the XPS hop sequence. Guys I'm 6000 miles from the nearest radio shack shop. One diode or one bloody screw missing and it takes me two weeks to get it. No ones forgotten the thread, guys have an investment in it with hardware and cash. Hang in and thou shalt see but it will not be before next weekend at the earliest.

Kiwi,

with all due respect, I would like to see the origional testing done by Xjet. The same testing that he kicked off this thread with, under the assumption of: "Independent tests prove lack of frequency hopping with XPS." That's what I'm waiting on.

[Kiwi]

%0%,

Without putting petrol on the fire thats a mute subject. Jim Drew even went on record to say the system DOES NOT HOP if it gets swamped by a sudden hit. He says it will hop if the interference ramps up.

Being able to RAMP UP is whats hard to do as you need some serious knowledge and access to some trick equipment to do it.

By just swamping XPS we know its dead, thats a fact. That dont need any proof from anyone and that is not the issue.

The issue is will it hop with a gradually increasing frequency clash. XJET is working on building that test device. Again its not his day job, he up to his butt in alligators doing a UAV tender and thats what pays the bills. I have been in touch with him, he is genuine and when he has the test gear we will all get to see his testing.

But the worlds not stopping waiting for him or me. It keeps turning, XPS, FASST, SPEKTRUM, ASSAN etc are all still selling and developing and god knows what else with new systems.

It will be here when its here unless you would like to do it faster for everyone.

If not wait like the rest.

[pilot232]

Allan,

Take your time. We can all wait a couple of weeks. We have waited this long, and want it done right.

Warm Regards,

Travis

[XJet]

	Quote: Originally Posted by ChrisHays
	44 or so days since this claim.. yet no proof ..got to love it!!!!

You're so right -- the only proof is the manufacturer's admission that it won't hop. Hell, you can't believe them can you?

[rede2fly]

guys just do your thing and dont worry about the hecklers. iam glad someone here even cares to take on something like this, much less having to listen to the hecklers but thiers 1 or 2 in every crowd. thing is, no matter what you find out with the extreme link system i wouldnt buy one. ok on with it

[ChrisHays]

	Quote: Originally Posted by XJet
	You're so right -- the only proof is the manufacturer's admission that it won't hop. Hell, you can't believe them can you?

im waiting on YOUR proof!... the flaws YOU are talking about... the issues YOU brought up.. it seems YOU have passed off the testing to kiwi.. which i look forward to hearing his results but YOU did an awful nice job of ducking THIS ONE...that is all

[KrisW]

	Quote: Originally Posted by ChrisHays
	im waiting on YOUR proof!... the flaws YOU are talking about... the issues YOU brought up.. it seems YOU have passed off the testing to kiwi.. which i look forward to hearing his results but YOU did an awful nice job of ducking THIS ONE...that is all

let's see. a Teacher once told me that the sky was blue .. . Ilook up, and it's blue. . gee. . kind of a no brainer.

Jim Drew says his XPS system will not hop if it's swamped. . we've had numerous total lockout crashes that act as if the receivers got swamped (because that's the only thing that will cause them not to receive. . right???) Again. . a no brainer.

Someone says tht because Jim Drew admits this flaw .. and it seems to be occuring in our planes, that there is an agreement of facts, like gee, it actually happens . .. and you DOUBT IT?????

After a manufacturer admits to a problem like this, it's not up to US to prove it. .it exists, for crying out loud. All we are doing now is testing to verify that it DOES exist. . where the actual thresholds are (as if it matters when we are flying. . . . ) what happens if it does hop, and how all the systems match up concerning tenacity for an RF connection, and how easily they can be jammed or glitched. The fact that XPS CAN be jammed or glitched has already been well documented. What happens afterward, and whether it is recoverable, is now the question.

I suggest re-reading all of Xjet's posts concerning his allegations, and where he got his information. It's already been typed several times. Perhaps you missed it.

[ChrisHays]

	Quote: Originally Posted by KrisW
	I suggest re-reading all of Xjet's posts concerning his allegations, and where he got his information. It's already been typed several times. Perhaps you missed it.

i suggest you re-read his posts and tell me who ran the "idependent tests" the thread title clearly implies :::::Independent tests prove lack of frequency hopping with XPS ...since "missed" it... thats what I want to know.. thats what most have wanted to know all along.. after the question was asked several times xjet jumped ship on this thread... it seems now someone else will be doing testing he is back on board... hows that new china system you are testing xjet?

[buttface]

I had a coil go bad in the ignition of my DA 150 and caused my XPS to lock out , falling for 8 seconds.I landed it with no damage.I was one of the lucky ones.I sold my XPS and will never buy another product from Jim Drue again.

[pilot232]

I believe that would have affeted Spektrum, Futaba, Airtronics, and XPS. Just my belief.

Travis

[4*60]

...

[pilot232]

4*60,

I feel the same way. If the noise level is that high, I don't believe there will be a clear channel for any system!! I am no giant here either, but 40+ years in computers leads me to this conclusion.

Warm Regards,

Travis

[XJet]

	Quote: Originally Posted by pilot232
	4*60, I feel the same way. If the noise level is that high, I don't believe there will be a clear channel for any system!! I am no giant here either, but 40+ years in computers leads me to this conclusion.

Sorry but this is just not true.

The 2.4GHz band is nearly 80 times wider than the 72MHz band and it's not at all uncommon for segments of the 2.4GHz band to have very high levels of noise -- while other segments are completely clean (ie: virtually no noise).

That's why frequency agility/redundancy is so important. If the channel your RC set is using is suddenly hit by a strong signal from elsewhere (not all that uncommon in some environments), it may only require a shift of 10MHz or so to move into a totally clear piece of the spectrum. If your gear is unable to hop under such conditions (XPS) or has no alternate channel already established then you're stuffed.

This could explain at least some of the growing number of "I flew XPS for months then suddenly..." reports that have appeared.

Both Spektrum/JR and Futaba have deliberately designed and implemented systems that can cope with such events -- XPS can't.

All systems work well while most of the time -- but Spektrum/JR and Futaba are far better able to cope with this kind of interference. If you're a gambling man then you may be happy to trust a $5K giant scale model to XPS.... ultimately it's a personal choice.

[Leseirf]

Xjet,
I posted this on RCG looking for an opinion from you but I think you were typing a post at the same time and missed it.

It occurs to me that there could be a simple software solution. The way I understand it (and I've followed pretty much every thread for the beginning) when the TX doesn't get acks, it retransmits. No acks for x amount of time it alternates looking on other frequency's with retransmitting on the original freq. Why couldn't the rx after x time with no signal just hop to clean air. The TX would then find it on its own. With the transmit-ack sequence being (IIRC) in the 2ms range and only 12 frequencys it shouldn't take long to re-establish connection.

That said I'm just a lowly RC hobbiest. No software or RF engineering background at all. This just seems logical given my understanding of how XPS works.

Mike