Independent tests prove lack of frequency hopping with XPS

[skubacb]

BaldEagel: Repeatable means that other people can repeat the same error around the country. I.E. a system fault.

I have around 2000 flights with XPS and have not experienced that problem. I believe you when you say you had the problem but it may have been just that environment. The XPS's reception seems to be a little more sensitive than the other systems. Since no one will fly out to 5 miles, I wonder if they should detune it some?

Of the people that have had problems I just can't see a repeatable link. It seems more random vice the Spectrum and FASST problems. Although, some FASST owners have the heat problem and some don't. Doesn't seem to be a single RX problem. At least XPS will talk with you. Futaba knows about the problem. They have one memo and basically are going to make everyone wait until this fall for some sort of answer.

[Toumal]

	Quote: Originally Posted by skubacb
	Here is a sobering thought. Nowhere have a read about or heard about, anyone that can cause a repeatable or testable XPS system failure. I am not saying that there might not be one but going off and calling people liars and talking about law suits without a drop of proof is lame, boring and irresponsible. Kiwi's "test" only showed that you can saturate the XPS system. It did NOT show that XPS will not hop. Time and time again it has been explained that it takes a specific environment to make XPS hop. A pure saturation of the 2.4 band is apparently it not it.

First of all: Thread resurrection.

Second of all: Kiwi's video was about interference, not saturation. There's a fundamental difference between these two.

Third of all: It is a fact that JD's "spherical antenna" has a blind spot, as does any other single ground-plane monopole design. There's nothing to debate about, this is how it is and every single piece of technical teaching and writing on the subject says the same thing. The antenna characteristics are well known and not up for debate, unless JD produces evidence of the contrary. Remember, it's JD who claims to have invented a magical antenna. It's always up to the guy who claims something to prove it.

Fourth: Kiwi's test is repeatable and rather well documented. JD, in his attempt to "debunk" Kiwi's test, fundamentally altered the test setup - he put the RX right up against the interfering transmitter, thus indeed saturating it. Well, except his own receiver, which he helpfully kept at a few more inches distance which, as you learn when you study this stuff, is a significant factor because the power falls by distance squared. And oh, JD did prove one thing: That his system didn't hop away from the interference.

Fifth: You having fown x amounts of hours without problems doesn't "disprove" fundamental design issues, like having the receiver request a channel hop from the transmitter. It's rather logical to conclude that this means trouble if someone just flicks a switch on their interfering 2.4 equipment, and Kiwi's test plausibly confirmed that. Doesn't matter if you fly 10 years without problems, tomorrow someone like me will switch on their 2.4GHz FPV system nearby while you're flying, and you will lose your aircraft, while the FASST and Spektrum guys stay in the air.


It's not about random and hard-to-grasp problems. It's really rather simple: XPS doesn't hop when there's an interfering signal on your channel that appears instantly, and the single antenna design has a blind spot that can cause loss of control under adverse circumstances. No system is perfect, but XPS is technically inferior.


Fly with it, it's your choice and your responsibility. But don't claim that the problems don't actually exist or that we're making this stuff up. And please, read the thread you're replying in before you write your answer. Thanks.

[ricoalonso]

second on that thread resurrection. I thought XPS finally released the long promised hopping video.

Anyway, as I asked in my deleted post in the XPS forum: Why did JD even wasted his time debunking Kiwi's test and even took him months to do it and yet not show that XPS will really hop? Publishing the hopping video (which he promised) showing that XPS will hop 'using the same parameters/criteria which he published himself' is the best way to debunk anyone's test or notion that XPS doesn't hop. So, why didn't he do that?

Thanks,
Rico.

[GBR2]

Probably because he has to work on all those other 30 or was it 61 new products that are going to be released by the end of the year. He has backtracked so often on what he has said, does it really matter if he produces a hopping video or not? According to everything I've read, the conditions to produce such a hop are so very specific as to be useless. So hopefully instead of wasting time on a hopping video one would hope he is spending sometime to rewrite the firmware code so his system does what he originally said it would do. Assuming that it is possible to do with the current hardware.

[ricoalonso]

Yes, I agree. Instead of wasting time to prove or debunk any test on the hopping ability of the current firmware, I think JD should concentrate more on the new capabilities and telemetry. It just surprised me that after the issue seemed to have been forgotten (or quited down) that some would dig it up again. But JD seemed to promise this capability in his new firmware (I think) as mentioned in a new thread (http://www.rcgroups.com/forums/showthread.php?t=889115) in his own forum and stated partly like:

"Obviously, we can make the system change frequencies whenever we want to. We know that exact method to use for bench testing. That method came from an accumulation of real world testing. That ability has now been improved by moving to a clear frequency when you instantly saturate the frequency... even though this will never occur in the real world. It may make the bench testers feel better, and perhaps give confidence to those that believe bench testing results are the same as real world testing results."

Anyway, hopping or not in the current firmware version is no longer relevant, IMO. Maybe XJet should have close this thread already.

Thanks,
Rico.

[BaldEagel]

Notwithstanding any of the above, my real world situation proved to me that the XPS system did not hop to another frequency, just locked out and gave me four brown trouser moments during the flight.

Closing the thread would not serve any usefull purpose other than stopping others who have an interest in not finding out that there is a possible problem with these units in some situations.

As I have said the area I fly in has no problem with Spektrum or FASST or PCM radio, it does have a consistant problem with PPM, but I am not saying that it is PPM interferance that is causing this problem, mearly that within the areas concerned some kind of interferance exists. To reitreate the areas concerned are in direct line with four long range communication towers on either side of a river estuary, these towers are not in sight, but have been plotted on an Ordance Survey map.

Mike

Mike

[XJet]

It's interesting to note that JD is now claiming he's written "millions of lines of code" during his software career.

This makes him a true God amongst men, since the industry-standard productivity for a good programmer when presented over the entire development cycle of a product is a mere 5-7 lines of code per hour.

This means that a good programmer would have to work continuously 24/7 for over 16 years to write just one million lines of code -- and JD's done several times that.

Does the man never sleep? Is he a super-programmer, the like of which we've never seen before?

Or could he be just full of BS?

Readers can choose their own answer ;-)

[sweetpea]

Xjet........there you are totally wrong.


I myself have written tons of code for products since I started in computers years and years ago. Maybe not quite a million but it is up there.

a million lines of code is not that big a deal actually and wouldn't take a lifetime to create. Video games are twice that. Keep the thread on topic please and keep your dislike of JD out of this.

Remember XPS is not just JD but Scott as well. JD just happens to be the spokesperson online

[socalsal]

	Quote: Originally Posted by XJet
	It's interesting to note that JD is now claiming he's written "millions of lines of code" during his software career. This makes him a true God amongst men, since the industry-standard productivity for a good programmer when presented over the entire development cycle of a product is a mere 5-7 lines of code per hour. This means that a good programmer would have to work continuously 24/7 for over 16 years to write just one million lines of code -- and JD's done several times that. Does the man never sleep? Is he a super-programmer, the like of which we've never seen before? Or could he be just full of BS? Readers can choose their own answer ;-)

Hi Xjet, tell me please, don't you think you have attacked this JD fella enough? You have made it very clear that your testing of his system does not do what you say it should do based on J's adds. I understand that you are very good in this testing field ( much better than I) But to continue with your bashing of this guy is just plain wrong don't you think.?
If I'm not wrong you are trying to develope your own design 2.4 based on the "Xbee" chip. Suppose you make a claim and somebody does testing and finds out that based on this testing your "claims are not true. Now suppose this other "tester" goes on a bashing mission to put you down, call you names and just plain destroy you as a person. How would you feel??? not good I'm sure. You might even get mad and fire back ( not recommended) This would just start a so called "name calling war".
JD seems to be smart enough not to get tied up with your campaing of personal attacks.

I'm not saying JD or any of his "claims" are true or not. I'm not saying you are wrong either.
But don't you think it might be a better idea to just maybe contact him on a personal basis and try to develop a system based on both of your ideas that would serve the modelers better?
This so called "war" you have declared on JD is now getting to the point that it is childish in my own opion. I would like to see your talents and JD's put to better use. You are well qualified to do some development in this area, but like they say." two heads are better than one".

I feel that you two could come up with a system that would be as good as any other maybe better and make some money for both of you. Right now JD is making the bucks and you are helping him do so with your constant attacks . You see you are making people aware of JD's product just by your actions

Anyhow Xjet have a very good day. I hope you will use your vast talents in a better way from here on out. You have made your point very clear about JD and his product. Time to move on to better things

[Edge 540]

Does an endless Do loop count as infinite lines of code?
I win

[Dustflyer]

	Quote: Originally Posted by skubacb
	Nowhere have a read about or heard about, anyone that can cause a repeatable or testable XPS system failure.

That's why politicians love us voters, we have such short memories.

Here are my videos of repeating XPS system failures:

[Kiwi]

Wow, this one is still pulling traffic and viewers. I'm amazed as I really thought it had fallen off the radar.

Just to reiterate so the facts don't get lost in the jungle of comments here.

My tests were not to prove XPS, FUTABA or SPEKTRUM or ASSAN were good bad or otherwise.

My tests were to see if under the exact same conditions the four systems would function. NOTE!!! Exact same conditions. I did not saturate the front end of any of the three tested devices. If I had done that they would have all failed.

What I done as shown clearly in the video was expose the systems to the exact same noise levels. That is the Rx was positioned in the exact same place from the noise in all three cases. The transmitter was in the exact same location.

The noise was not ever dumped in a solid burst on any one channel. If you look at the scanner you can see the spread was wide enough that as the noise transitioned across the specktrum each channel was slowly exposed. It was never hit with a solid burst such as a video transmitter etc would do.

XPS stopped functioning every time.
ASSAN stopped functioning every time (it should do as it is not sold as a frequency agile system as are the other three)
SPEKTRUM never missed a beat, performed solid all the way through.
FASST never missed a beat, performed solid all the way through.

Now what conclusions anyone wishes to draw from that is over to the individual. I do not say XPS or ASSAN are bad but they do not perform as well as the other systems do. That's a fact, undeniable real world solid fact. But it does not make them unusable. It just means they are not as robust as the two better performing systems.

My feelings as a guy who takes extreme pride in the building, flying and the safety in this hobby tells me that if I want the best and most secure frequency agile system then I should use S or F. But I dont have to, I am not saying dont use the the others. I find ASSAN absolutely great to use in my foamies and fun fly stuff that I fly in the paddock behind the house. But in my high dollar stuff I can not justify using an inferior system that saves me $100 maximum in a model that I have invested $5000. to $7000 in. That's my point.

Fly what you like when you like but if you seriously want to protect your investment and asset I am sure you will not penny pinch when it comes to the most important part. The radio link that lets you drive the thing in the first place.

However it was never ever going to be long before someone else came along with a true FHSS system that will retro fit the big name radios and it is already in testing. Once they get the bugs out of that set-up I hope we can put it through the same barrage of tests the others were exposed to.

After all they are 100% repeatable in the same location with the same devices and instrumentation.