Independent tests prove lack of frequency hopping with XPS

[sweetpea]

The sky isn't falling buttface, though maybe its getting cloudy

It does appear for now that the system does not hop. One could make a case that 2.4 could have more interference on it than 72, but if it truly does not hop it will act just like 72 during interference. Set your failsafes and your plane is no more a killer than 72. Many places in the world (including the USA) will be just fine for 2.4 while other will not. Its very similar to why some fields have banned individual 72mhz freqs (ch19 for example)....they just don't work there.

Like 72mhz though......it will work fine until it comes across something on its freq (assuming it does not hop like the tests so far have shown) And just like 72mhz there is no way of knowing once you are airborne and flying and your plane goes into lockout is your first clue. If someone turns on the interference your screwed on both....you may have been good today, you may have been good 5mins ago....just no way to know until after the fact. And that my friend is true on 72 or a non hopping XPS.

Now if you want to make the argument that their are better 2.4 options based on interference rejection techniques I'd buy that one. I could even understand at some fields you could treat non interference rejections systems on 2.4 being banned if you have an unusual amount of those systems being shot down due to high noise levels at the particular field. But I wouldn't blanket that across the entire R/C community. We don't do that with individual 72mhz freqs...it needs to be field by field restriction.

(this would affect things like ASSAN and other low end units that only rely on one freq and could affect XPS if no one can prove it does hop)


As for the posts about bodily harm......I'd really like to see these go away. We are about to open a huge can-o-worms on this that will effect all R/C flying. Since anytime we have any kind of lockout or system failure on any brand radio/servo/airplane we could have bodily harm. Didn't we just see the whole lawsuit from Horizon about "Made in USA vs Assembled in USA".....just sit back and think about it closer before comments like that are strewn around the net.
I'm sure your intentions are good but the best intentions usually have the worst outcome in life.

And remember....all of our radios have to abide by the FCC....."accept interference" clause. This one clause is the R/C communities biggest downfall when you start looking at planes that have real potential to inflict harm.

Now just because you accept interference doesn't mean you can't try to avoid it by moving or having backup freqs. But 72 has been using one freq for quite some time, and a great many planes have gone in, be it from radio shoot downs, electrical issues, RF intereference generated from the plane or some wierd unexplained lockout. Are there better options.....depends on your specific radio and the field you fly at. For some XPS could be the best thing. For others it could be the worst choice.


Feel free to keep up the false advertising or false claims......but leave the bodily harm alone.

[buttface]

	Quote: Originally Posted by sweetpea
	The sky isn't falling buttface, though maybe its getting cloudy It does appear for now that the system does not hop. One could make a case that 2.4 could have more interference on it than 72, but if it truly does not hop it will act just like 72 during interference. Set your failsafes and your plane is no more a killer than 72. Many places in the world (including the USA) will be just fine for 2.4 while other will not. Its very similar to why some fields have banned individual 72mhz freqs (ch19 for example)....they just don't work there. Like 72mhz though......it will work fine until it comes across something on its freq (assuming it does not hop like the tests so far have shown) And just like 72mhz there is no way of knowing once you are airborne and flying and your plane goes into lockout is your first clue. If someone turns on the interference your screwed on both....you may have been good today, you may have been good 5mins ago....just no way to know until after the fact. And that my friend is true on 72 or a non hopping XPS. Now if you want to make the argument that their are better 2.4 options based on interference rejection techniques I'd buy that one. I could even understand at some fields you could treat non interference rejections systems on 2.4 being banned if you have an unusual amount of those systems being shot down due to high noise levels at the particular field. But I wouldn't blanket that across the entire R/C community. We don't do that with individual 72mhz freqs...it needs to be field by field restriction. (this would affect things like ASSAN and other low end units that only rely on one freq and could affect XPS if no one can prove it does hop) As for the posts about bodily harm......I'd really like to see these go away. We are about to open a huge can-o-worms on this that will effect all R/C flying. Since anytime we have any kind of lockout or system failure on any brand radio/servo/airplane we could have bodily harm. Didn't we just see the whole lawsuit from Horizon about "Made in USA vs Assembled in USA".....just sit back and think about it closer before comments like that are strewn around the net. I'm sure your intentions are good but the best intentions usually have the worst outcome in life. And remember....all of our radios have to abide by the FCC....."accept interference" clause. This one clause is the R/C communities biggest downfall when you start looking at planes that have real potential to inflict harm. Now just because you accept interference doesn't mean you can't try to avoid it by moving or having backup freqs. But 72 has been using one freq for quite some time, and a great many planes have gone in, be it from radio shoot downs, electrical issues, RF intereference generated from the plane or some wierd unexplained lockout. Are there better options.....depends on your specific radio and the field you fly at. For some XPS could be the best thing. For others it could be the worst choice. Feel free to keep up the false advertising or false claims......but leave the bodily harm alone.

Bro, are you a lawyer?

[JEFFRO503]

Nah...sweatpea aint a lawyer , but he makes a lot of valid points.

The thing is , when everyone switched over to the 2.4 stuff , it was all supposed to be a safer way to fly. But JD jumped on the chance to copy exactly what 72mgz was doing in the first place , but just put it on another band. And told everyone that it would be impossible to get locked out , if you used his system. Well......he never stated "impossible"....but pretty close. At least with Spektrum and JR you have a couple different channels it can choose from , and futaba changes channels about 200 times per second......so your chances of losing your aircraft are a lot slimmer.

I'm waiting for what ol' JD has to say about all this stuff. Wonder if it can be fixed with software programming , and make it downloadable for the masses , or offer a free upgrade and send all the equipment back to get it fixed. He has a chance to at least fix the problem now , before anyone else looses an aircraft , or even worse yet.........somebody gets hit by an aircraft in full lockout!!!

[XJet]

SweatPea is right, just because we seem to have found a major flaw in the way that XPS handles (or should I say "doesn't handle") strong interference on its chosen operating channel doesn't mean that everyone's XPS-equipped models will suddenly fall from the sky.

What this does is simply increase the risk of flying XPS when compared to other systems that offer either redundancy or frequency agility.

It would appear (although I've not seen one to check) that the Assan is a single-frequency DSS system that will have the same (or perhaps even more) susceptibility to this kind of hit. Certainly the cheap Chinese 2.4GHz system I've been flying for the past month or two is also a single-frequency system without agility or redundancy and I've had no problems yet (touch wood).

What it does mean however, is that when weighing up which 2.4GHz system is best for *you*, it's important to realize that the risks assocaited with XPS may well be higher than those associated with Spektrum or FASST (the present ZGUID issue notwithstanding).

Right from the get-go (early May last year) I warned that XPS was not a system I considered suitable for very large models, and that was even before the frequency-hopping issue became apparent. I believe that even more strongly now.

I would never (for example) use this cheap Chinese gear 2.4Ghz gear in anything more valuable or dangerous than a .40-sized profile -- it's just not worth the risk because I *know* it has very limited ability to cope with some quite common forms of 2.4GHz interference. It works well on a cheapy 3D slab though and represents a great price-point (with receivers costing under $40) and, since my expectations were not high I'm not disappointed. If/when I lose a profile to this gear I won't cry -- I'm expecting it (sooner or later) and balance that risk against the cost-savings it offers me right now.

Those who are lucky will never have a glitch or a problem with XPS, even in a large model.

Those who are particularly unlucky will lose planes no matter what RC gear they're using or what frequency they're on.

However, when it comes to games of chance (such as flying RC models) I prefer to stack the deck as much as possible in my favour -- and if that means choosing a 2.4GHz system that makes me less likely to be shot down by interference, that's what I'll buy for my bigger, more valuable or more dangerous models.

It's a personal choice thing, and those who are happy to chance their luck will doubtless continue using XPS (many with great success). Those who prefer to keep risks to a minimum may opt for something a little more resilient.

It's also worth noting tha the latest addition to the world of 2.4GHz RC systems (Sanwa) is using frequency-hopping SS. The fact that all the major players have opted for redundancy or frequency agility kind of puts XPS (with neither) in the same category as the cheap Chinese stuff now.

[jonkoppisch]

	Quote: Originally Posted by sweetpea
	The sky isn't falling buttface, though maybe its getting cloudy ..... Feel free to keep up the false advertising or false claims......but leave the bodily harm alone.

The sky isn't falling... but it seems that many xps planes are...

I don't know if it's false.. I do know that when my jet went out of control it was headed for the south end of our pitts where a lot of people were standing. I thought that was what was going to happen so I can't agree with the danger level!!

[Kiwi]

Gents,

Just to keep you up with things most of my test gear arrived Thursday and I have spent some considerable hours getting used to the software.

The two systems I have available to test today are XPS and ASSAN. Already I have found some information that I need to dig deeper on.

FASST and SPEKTRUM are next week.

I am playing around with this stuff currently in my apartment and its smack bang in the middle of the city. Its a pretty noisy 2.4 environment as the information will show later.

First surprises with the ASSAN units is they seem to always want to start up on channel 1. Even if channel one is cluttered the ASSAN still looks there and stays there. I have not been able to make it start on any other channel.

Second surprise with the ASSAN system is signal strength. It barely makes a shadow on my scanner and certainly not anything like the shadow XPS delivers.

ASSAN is non skipping so my intention with it is to see how much noise it can handle before it goes into fail safe. We are not looking for anything else with them.

XPS does look around before selecting a frequency and you can see that very clearly. It has a very strong frequency profile compared with the ASSAN system, hopefully today I can start throwing some noise at it and see if it even remotely wants to try and hop a channel. I'm open minded as to if it will or it wont despite the other tests.

As soon as I get something I will post it in this thread.

Thank god for apartments guys. Imagine if the lawn needed mowing, the garden needs weeding etc. Time that could be spent playing ( Really working) on this stuff.

If I get into some grey zones I will also be asking for opinions and help here guys so this is a team effort, not a dictatorship.

Stay tuned.

[sweetpea]

	Quote: Originally Posted by jonkoppisch
	The sky isn't falling... but it seems that many xps planes are... I don't know if it's false.. I do know that when my jet went out of control it was headed for the south end of our pitts where a lot of people were standing. I thought that was what was going to happen so I can't agree with the danger level!!

jon-

truly it is scary that your model reacted that way. Was it anymore dangerous than a lockout on 72? Only if you flew your model in a way expecting to never have a lockout due to any kind of interference. That is understandable due to the advertising from all the companies. I for one have never trusted that advertising stating that all intereference is immune. I install my radio gear and fly my models expecting some sort of issue. I try not to fly at/over/near the pits and set my failsafes to idle and last known. If something did happen, I know I had no control and would be just a liable as anyone else. One of the reasons I pay for my AMA.

Xjet brings up a good point that I sort of agree with. Basically that (if XPS has no hopping) XPS would not be the best choice. I agree.

Here is where I disagree. XPS could be your best choice if your flying an older radio that Spektrum/FASST do not support. If you fly in an area farther away from 2.4 sources then I would lean toward XPS being safer than 72.

Now if you fly in a more populated area where 2.4 products are more popularthan 72 or one of the other 2.4's with interference rejection would be safer.


Its great that Kiwi is starting his testing and I'm glad he doesn't have any Manly chores to attend to so us "tech geeks" can have some answers.

[sweetpea]

	Quote: Originally Posted by buttface
	Bro, are you a lawyer?

Nope, not a lawyer.

But I did stay at a Holiday Inn Express!

[klhoard]

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I bet the Fanboys are HOPPING mad about this!!
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JD better HOP TO IT and get this issue fixed!!
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Sorry guys, been out in the garage sniffing glue this morning. . .
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[bjon]

delete

[DadsToysBG]

XPS has some advandages over 72. The issue I see is that the hype didn't match the performance, and a lot of people were shot down for asking questions. I never thought it was brand war. They were good questions that never got good answers. Even when spektrum had issues with low voltage some didn't like the answer (better batteries) so they (spektrum) made a fix at no cost. Futaba has issues, now theres a lot of babble but they are correcting it at no cost to their customers. Now we wait and see what happens to XPS. Based on his past record with other products I don't expect much, but I hope not. I want to see everybody to have a system working that answers their needs. We now have three companies with systems that work as advertized . I don't think I remember anybody asking for tests to be done when we went narrow band. We accepted the fact the all the major players in radios for the hobby would do right by us. And they have always meant my standard of service. Dennis

[Four Stroker]

Kiwi Please take into account in your testing that there are many flavors of each 2.4 GHz protocol which may have different performance characteristics:

Spektrum DSM, DSM2
FASST 6 Channel, 7 Channel, Multi-channel
Airtronics Only 8 channel
XPS Only ZigBee

[Kiwi]

Guys,

I'm using two different systems to test these radios and Rx's with.

Your going to see a whole lot more on the two companies who supplied us with the test software and hardware. These two companies have really bent over backwards to help us ( FG ) bring as clean an answer as possible to you all regarding the 2.4 Ghz RC systems available.

Todays testing has been a fruitless event in so much as no matter how hard I try there is no way I can get XPS to hop.

Here's the basis of my tests so far.

I am using a device called AIRHORN supplied by www.nutsaboutnets.com

This device is a selective transmitting device that can:
Transmit on one selected channel ( 1 thru 11 )
It can traverse all the channels sending a fast or slow transition between channels (Traverse mode)
It can pulse on a selected channel (1 thru 11) with a selected duration between 5 and 60 seconds and a selectable wait time between pulses 5 thru 60 seconds.

To see what is happening the guys at Meta Geek supplied us with a Wi Spy unit and a spektrum analyzer. This Chanalyzer as they call it is a full on data recorder and you can leave this thing recording in real time all day if the need arises. That way if you had an event at your field you could easily go back and see what was happening in the area when it happened. Its likely something not many people need to do or want to do but its there if needed. At big events I honestly think it would be good idea while all the 2.4 issues are high on the discussion list.

However the Wi Spy is absolutely a must have tool for those who want to know what the environment is (2.4 Ghz) around them or at the field. It comes in two version. One with a detachable antenna and the other with a built in antenna. The top of the line unit costs little more than a top digital servo so go figure if its worth the effort.

You can find out more about them at www.metageek.net

OK so what has happened so far.

Lets just stick with XPS for a start so we dont things all mixed up.

XPS does look for clear air on start up. So far I have been able to have it start on 6 of the 11 WiFi channels available. Zigbee channels appear to have 16 on the data logger but I'm not at all knowledgeable enough to go into what the differences are.

OK with the XPS on channel 1 I can bring the noise level up to within 20 DBm of the XPS unit and it will not hop. Pulsing or just a straight hit, it will not move no matter what I throw at it. I dont think I have many more options to make it hop as I have maxed out the power of my AIRHORN. The channels either side of 1 were clean and had limited or no traffic on them at all yet the Tx and Rx would not move.

Given the circumstances in the other tests XPS did not hop when swamped, and it does not appear to hop when the noise floor is ramped up either. I think by pulsing an interfering signal all around the working channel would induce a hop if anything could. Well so far nothing.

I will post a video this evening of the setup and the way I attacked the XPS so you guys can be the judges.

I need a beer, its hot down here guys.

[klhoard]

Kiwi,

Any chance you can run some tests with the 2.4Ghz cell phone jammers to see what their effects are on these systems?

[Kiwi]

Funny you ask. I have one on the way but I will save that for last as I dont want to muddy the water too much before I have a chance to do all my tests in an operational type environment.