Independent tests prove lack of frequency hopping with XPS

[Wojcigitty]

XJet, thanks for starting this thread. Your posts have been tremendously enlightening, and I truly appreciate your efforts.

Kiwi, I hope the rest of the testing goes well. The more we know, the closer we are to finding or implementing the safest possible control solution for large RC stuff.

Earlier in the thread the inherent issues with 2.4 were brought up. That made me think. Suppose I am using a 2.4 Ghz device, and then, quite legally, the channel(s) on which I am operating are flooded, by some other device. Now, if I was using the 2.4 band to browse the internet, I lose my connection, swear, and have to refresh the FG homepage. Inconvenient, but no big deal. Or I might lose my cordless phone connection, or the bluetooth headset I'm using doesn't work, or whatever. My point is, none of these things are mission-critical. They temporarily don't work, and nothing really happens.

But if this happens to me when I'm flying my RC model on 2.4, it could cause a crash, safety hazard, etc (I won't go there).

My question is this: is there anything that operates in a manner similar to our RC stuff on 2.4 (ie the connection absolutely can not fail)? If no, then maybe 2.4 really isn't a good choice; maybe it's not meant for something like RC aviation.

[XJet]

Thanks for the kind words...

The ideal solution for RC would be to have some dedicated spectrum dedicated solely for RC use at a high-enough frequency that we could use still SS techniques.

Right now, 2.4GHz is a battlefield where it's only thanks to the technical merits of SS technology that we're able to use it for anything at all.

There are some advantages to 2.4GHz though:

It's a short enough wavelength (high enough frequency) that distance is a great barrier to interference. If you're out in the middle of nowhere, miles from any other 2.4GHz devices or services then you're pretty damned safe. The path loss for 2.4GHz is quite high and it's also fairly much line of sight which means stuff that's below the horizon or behind a mountain isn't going to hurt you. Even stuff you can see will be of no matter -- if it's far enough away that its signal is simply absorbed or dissipated before it gets to you.

Of course since the RC hobby is a relatively non-essential use of the radio spectrum, it's unlikely that there'll be any band of frequencies allocated specifically for it and, even if there was, the cost of RC gear on those frequencies would likely be a *lot* more than the 2.4GHz stuff we're now using.

The only reason that 2.4GHz has taken off for RC use is that there are plenty of "solutions" (chipsets and modules) designed for other things on 2.4GHz (such as WiFi etc) which can be pushed into service for RC links. Of course this also means that there are limitations to some of the current generation of 2.4GHz radio gear because few of those "solutions" were actually designed for robust, resilient, highly mobile, real-time telecontrol applications.

With the ever-growing flood of cheap "gadgets" operating on 2.4GHz coming out of China I can't see the band getting any friendlier for RC users. This means there will always be fields that are simply too risky for 2.4GHz RC use, while others are interference and trouble-free on this band.

[airborneSGT]

So we could also stick with the "old" system with more frequency control? I don't see why the old system would not work with some type of frequency hopping in which it would only recognize the model you fly.

[Kiwi]

OK gents,

I have about a week of playing with the systems under my belt and I'm about ready to put in print the tests and what I have found.

What I will do is start a new thread for each brand and do the videos, graphs etc in them. But system by system as it gets a way too meesy mixing this stuff up in the one pot. Plus I suppose if anyone wants to go back later and see what was said they dont have to wade through 600 posts to find it.

I think I will close the actual data threads after each post. But I will post a link to a discussion thread about the results. Again to keep the chatter out of the data.

Another reason to do it this way is I have been informed of yet another system due out very soon that just might be superior to everything we have available so far. I cant comment on who or what it is but as soon as we get the green light we will have it on FG. Guys I hate keeping secrets but this one has me sworn to saying nothing until the legals are done. However it looks to be a whoop ar$e system. Dont PM me and ask. You guys will know when I know.

So look for the new threads for info. I wont post here much in future unless its just general chatter.

[jonkoppisch]

	Quote: Originally Posted by Kiwi
	... Another reason to do it this way is I have been informed of yet another system due out very soon that just might be superior to everything we have available so far....

Any guess how long it might be before it's out? (I know that you're not responsible for release dates, just a guess is all) I have the 14ch fasst system on backorder. I'd hate to buy it then find a much more reliable system, but if it's not going to be out for awhile...

[Kiwi]

Ask me no questions and I will tell no lies.

Be assured when I know you guys will all know. I have no dates, nothing, just information thats somethings in the wind. Not rumors, real facts.

[jonkoppisch]

Keep us informed kiwi!!!

Thanks

[Woketman]

Please post links to those other threads when they exist.

You are my hero, Kiwi!!!

[Wojcigitty]

	Quote: Originally Posted by airborneSGT
	So we could also stick with the "old" system with more frequency control? I don't see why the old system would not work with some type of frequency hopping in which it would only recognize the model you fly.

I believe that the reason for not doing this (aside from the Polk's thing) is that
a) 72 Mhz does not have enough bandwidth for a signal layer to control frequency agility
and
b) as XJet said, there were more chipsets / knowledge available to implement spread-spectrum on 2.4 Ghz.

	Quote: Originally Posted by Kiwi
	Another reason to do it this way is I have been informed of yet another system due out very soon that just might be superior to everything we have available so far.

[klhoard]

	Quote: Originally Posted by Kiwi
	Ask me no questions and I will tell no lies. Be assured when I know you guys will all know. I have no dates, nothing, just information thats somethings in the wind. Not rumors, real facts.

.
.
Is it going to be produced by our favorite "Extreme" R/C product dealer?
.
.

[50%plane]

Kraft single stick on 2.4...... lol


Kiwi, I can't wait to see it, whatever it may be. I'm in the market for a higher end 2.4 system right now. I hope that new system might fit the bill so that I have another option to consider.

[ricoalonso]

	Quote: Originally Posted by Kiwi
	... I have been informed of yet another system due out very soon that just might be superior to everything we have available so far. ...

Ok, I got another excuse not to 'hop' to 2.4GHz yet. Although I do hope this one is not just like the other which claimed to be superior than rest but up to now, still needs to be proven.

^R^