Independent tests prove lack of frequency hopping with XPS

[Edge 540]

.

[luv2flyguy]

It's Christmas for goodness sake!!
Why can't we all just get along!

[XJet]

	Quote: Originally Posted by sweetpea
	I would like to see these "independant" tests as well. And where Spektrum and Futaba systems part of the test? If not, these tests have not proved one system better than another.

I suspect the problem is that to some folks, JD is God and XPS is a religion based on faith. Anyone who questions that faith by raising points of fact gets roundly demonized for their trouble.

I have no doubt that even when the evidence is posted, the XPS devotees will claim it was rigged, or that the two XPS systems tested must be both faulty, or that Mars was in the seventh house, etc, etc.

That's fine, I don't expect to convert the fanboys, my only goal is to provide everyone with more objective information on which to base their decision-making.

	Quote:
	We all could create a test on Spektrum to show that it can't handle voltage issues very well but without including all the other brands it means nothing. The other brands claims of being better could actually be worse. Same with what your saying about Freq hopping.

Untrue. Nothing Spektrum or Futaba does has any bearing on the fact that XPS does not have robust frequency agility or frequency redundancy.

	Quote:
	Did your test look at how fast Spektrum looks to its second freq? Or did it look at how close the 2 freqs are where an overflow of signal may effect both? How about Futaba hopping.....what if it hops to numerous used freqs in a row? Or if the noise floor is high as well? What if it can't detect the signal interference?

Again, this is not really relevant. A spectrum analyzer shows clearly that Spektrum uses two independent frequencies, both of which carry the data-stream. Likewise, others have already tested and proven that Futaba does indeed use frequency hopping.

	Quote:
	If your going to bash one........bash them all please.

Sorry Sweatpea but that's fanboy talk. I'm not "bashing", simply pointing out that yet another one of XPS's claims is unfounded. If I were making claims against XPS as wild as the claims that are made for it by JD -- then I'd be bashing.

	Quote:
	And once Futaba has been out for a year or more and starts putting up the numbers that XPS and Spektrum have.....we shall see their weak points as well.

And indeed, I'll be looking at Futaba's system when time/finances allow. However, neither Futaba nor Spektrum are making claims that defy the laws of physics (spherical antennas) so have to admit to being less confident of finding such wild misrepresentations.

	Quote:
	Since of course you are only going by what a company tells you their system does. Xjet refuses to believe in the comments of XPS (which is his right) but takes blindly what Spektrum and Futaba says and has no "independant" tests on them? Why not? Do you think we aren't interested in those results?

Okay Sweatpea, as a fanboy, you're not interested in learning of the weaknesses of XPS -- that's fine. But I think (and posts here seem to confirm) that others are.

You'll note that I have never said "XPS bad, don't buy" -- I've simply done my best to objectively point out that XPS has another rather significant weakness when compared to its competitors.

This weakness has been admitted by JD and he's even said he's working to fix it. My question would be -- if it's not broken, why would you waste time fixing it?

I notice since I presented my evidence, JD has taken to trying to question my skills and experience in the RF field -- making childish remarks relating to the fact that I have a jet-powered gokart (relevance??)

The fanboys also refer to anyone who dares question their faith or the word of JD as "self-appointed experts"

Well...

If you recall, I questioned XPS's antenna claims right back at the beginning, when JD was swearing black and blue that the tiny quarter-wave whip in the transmitter module as all that would ever be needed for bullet-proof operation.

Then, suddenly that wonderful quarter wave *wasn't* actually good enough for all situations so now XPS sports an external dipole.

I also queried XPS's lack of diversity antennas or satellite receivers, but those criticisms were roundly discounted as rubbish by JD. Then, as if by magic, XPS announces the upcoming release of satellite receivers.

I then queried this "essential eight element antenna" that is apparently a magic feature of XPS and unqiue to it. Even when I posted side-by-side images of a stock XBeePro module and an XPS one with no sign of a magic antenna -- I was told I was wrong.

When I asked therefore, for the name of the testing lab or university that determined the effect of this miracle antenna -- there was absolute silence.

Obviously I know absolutely nothing then... right?

These are the reasons that I treat any claim made by JD with great skepticism and dismiss the ravings of the fanboys as being akin to that of a religious cult..

	Quote:
	I'm not saying XPS is all that.....Nor am I saying that about Spektrum or Futaba. I am saying that all 3 systems are far better than 72mhz as far as interference is concerned. Which is why I went to 2.4 to start with.

You're right -- in some countries (such as the USA), 2.4GHz may be better than VHF but there are countries where frequencies have been specifically allocated for model control and in those places, providing the clubs have effective frequency controls in place, 2.4GHz may *not* be the best alternative because it really is a "free for all" band.

As I said in the first posting to this thread, XPS will likely work fine for most people but users ought to be aware that there's no contigency for the sudden appearance of a strong interfering signal on the frequency XPS has selected at boot-up time. In this respect it is inferior to its competitors.

It s a free world though and I invite people to purchase and use whatever they want.

[exeter_acres]

Your thread would have held much more water if you started it with your proof versus making claims with no proof (YET) to back it up......and saying it will come later.......

Might have gone differently

[bodywerks]

	Quote:
	Sueing seems to be the favourite pastime over there in the US.

Sad but true...

[madmax]

XJet, we invite all modelers who have the knowledge and experience in testing equipment to post their findings here, so long as it is done respectfully. Send 'em over.

[bodywerks]

I for one lost a little faith in X-link when they added the makeshift antenna to the module. But I know people that are happy with them, and I am happy with my Spektrum. I will let this thread go...

[gmilo]

I for one lost faith in X-link when JD claimed that the 1st delay in introduction was due to a delay in receiving plastic receiver enclosures from the Asia supplier that 'were in transit'.....this transit time turned out to be about 6 months. Just a bold face lie IMHO that I didn't appreciate as a reasonably intelligent consumer. When I go 2.4, it will be JR or Futaba, but not XPS

[sweetpea]

Funny. I'm happy that Xjet has taken the time to post his findings.....yet not post how the findings came about, who the testors were and how controlled the experiments were.

Again I'd like to see what the test entailed so that they can be put up against all 3 companies equally. I'd like to see what it takes to fail Spektrum on the 2 signals, how close they really are, what effect the floor noise has etc. I'd like to see the effects of the same thing on Futaba.

And I would not say I'm a "Fanboy" of XPS. I will say I'm a "Fanboy" of 2.4 They all have strengths and weakness's. All 3 of the companies have flat out lied in the advertising about "immune to intereference" I fly both Spektrum and XPS. I don't fly futaba because that would require me to buy a new radio.....My 10X isn't broken so why buy a new one?

Since I wasn't flying R/C back when PPM went to PCM I suspect the same type of false advertising happened then and planes were lost and continue to be lost and will be lost in the future as well.

And no one has disputed that XPS has found some problems with their system in the average joe's hands. Such is the life of electronics. Spektrum found the same thing out (battery voltage ring a bell). You cannot possibly test every situation that some moron will put your system through. No different than a car being recalled from Ford or Chevy. I guarntee Futaba will see the same thing once they start hitting the market hard.

As for the satellite rx's from XPS......they were stated from day one to be an option. I for one don't care what any of the 3 companies have to say about signal strength/path etc. 2.4 is a narrow beam on a narrow antenna. On a large plane too many things get in the way. Give me multiple antennas (similar to 72mhz which put the antenna the length of the fuse) so that the signal has a better chance of being recieved. I'll pay the extra money for the extra piece of mind. To me that's no different than using extra batteries or switches or dual RX's in 72mhz.

But the best part of all of this.............

I should not take the companies word on how their system should work......But I should take yours (or your independant testors) without any proof

Thanks for clearing that up for me.

[sweetpea]

	Quote: Originally Posted by madmax
	XJet, we invite all modelers who have the knowledge and experience in testing equipment to post their findings here, so long as it is done respectfully. Send 'em over.

Heck yes.........bring the data on.

I'm all for knowing exactly why something works or doesn't with the reasons behind it.

[jonkoppisch]

I wish that I had known about the 'exaggerations' before I purchased the xps system. One of the main reasons that I bought it was that it was promoted that it would jump to another channel if it encountered any interference. It sounds as if there are only 11? channels that it can switch to if the circumstances are just right. It worked for me.. Then it didn't...

[XJet]

	Quote: Originally Posted by sweetpea
	But the best part of all of this............. I should not take the companies word on how their system should work......But I should take yours (or your independant testors) without any proof Thanks for clearing that up for me.

But JD himself has has (when confronted with the truth) has admitted that XPS will not frequency hop when exposed to a sudden rise in the noise floor or strong interfering signal. So why question my findings when JD has confirmed them?

You're saying JD is right when he says it won't hop but when I say it won't hop, I'm not to be believed without proof?

Do you not get it.... JD said (direct quotes):

"The frequency hop requires a rise in the noise floor over a number of frames. A sudden saturation will reset the noise counter and not switch at all."

"If the noise becomes so high that it saturates the channel, the hopping counter is reset and the system will not switch"

So, even if I didn't provide proof (which I will), why would you question this? If JD says it's so, surely it *must* be so.

Why would he admit to a non-existent flaw in his own system?

The XPS won't reliably frequency hop when hit by sudden interference -- this much is beyond doubt, even JD admits it.