Independent tests prove lack of frequency hopping with XPS

[jonkoppisch]

You should probably add battery voltage issues to xps... At least that's 1 of the things that they threw at me It has been reported pretty often with the xps units as well, although, probably not as much as with spektrum. That could simply be accounted for though by the larger #'s of spektrum units that are sold.

That and not setting the failsafe will evidently cause you to crash as well

[Pale Rider]

You can also add to your Spektrum list that the reboot time on the last 2 rx's developed (r921 and ar9100) is less than 1/2 second.

[snap a saurus]

I thought I knew the 2.4 Ghz system, there is more to it and hopefully most of the problems will be fixed so we can have a reliable and safe system.

[sweetpea]

	Quote: Originally Posted by jonkoppisch
	You should probably add battery voltage issues to xps... At least that's 1 of the things that they threw at me It has been reported pretty often with the xps units as well, although, probably not as much as with spektrum. That could simply be accounted for though by the larger #'s of spektrum units that are sold. That and not setting the failsafe will evidently cause you to crash as well

2 things.....
1)I don't think the large number of units is the issue as much as XPS has not released the 6ch rx (parkflyer/electric) yet. This is where most of the voltage issues showed up was from folks running electric airplanes where your voltage is going to drop faster (that and the giant scale use of 8711's) If they had been released at the same time or so, then voltage may have been an issue for both, but as it stands, 90% of the folks now know to watch out for voltage on 2.4 gear.

Failsafe is not an issue in my book.....on any RX you should be setting a failsafe of your chosing. Not setting your failsafe is not going to cause you to crash.

2) XPS reboot voltage is less than Spektrum so I left it out as a real issue. It looks as though Spektrum is the highest reboot voltage on the market.

	Quote: Originally Posted by Pale Rider
	You can also add to your Spektrum list that the reboot time on the last 2 rx's developed (r921 and ar9100) is less than 1/2 second.

That is a definite improvement over the 3 or 4 second reboot but not a fix for the battery voltage issue. If my rx is shutting down on low voltage it is still shutting down (no matter how short of time) and when there is still enough juice to run my servos why is my RX shutting down?

[jonkoppisch]

I was just going by what they claimed on me when my jet crashed... It was a power problem (yet there was 2 battery packs that tested good under load), then the receiver failsafe wasn't set. Then a servo or (which I'm using in a new plane with no problems) ....

Hey, quick question. With the unlimited warranty, I wonder if there would be any replacement issues if I start using the xps in combat

[sweetpea]

they now claim full replacement for any cause of failure. Though full contact combat may not be covered since you are intentially putting the unit in harms way. A simple email would let you know for sure

[jonkoppisch]

I could always claim that I had the failsafe set wrong

Before anyone panics... JUST KIDDING!!!

[Pale Rider]

	Quote: Originally Posted by sweetpea
	That is a definite improvement over the 3 or 4 second reboot but not a fix for the battery voltage issue. If my rx is shutting down on low voltage it is still shutting down (no matter how short of time) and when there is still enough juice to run my servos why is my RX shutting down?

IMO the low voltage reboot issue is really a moot point. I have no experience with electric planes so it may be a different story there, but there is no reason to let your rx packs go below 6v (assuming your using 6v packs) in glow or gas planes. Yes S---t happens and possibly something may occur while you are flying, but the lower the voltage gets the more sluggish the controls so I would think a pilot would get an indication of a problem before the voltage gets under 4v. All the more reason to check between flights with a 1-2A load.

[sweetpea]

	Quote: Originally Posted by Pale Rider
	IMO the low voltage reboot issue is really a moot point. I have no experience with electric planes so it may be a different story there, but there is no reason to let your rx packs go below 6v (assuming your using 6v packs) in glow or gas planes. Yes S---t happens and possibly something may occur while you are flying, but the lower the voltage gets the more sluggish the controls so I would think a pilot would get an indication of a problem before the voltage gets under 4v. All the more reason to check between flights with a 1-2A load.

I agree 100% on this.........I was just looking out for those electric flyers out there in stating problems of each system so they may make a more informed decision based on facts. What I laid out was just that......facts, backed by the manufacturers

[Pale Rider]

Agreed--Like I said electric stuff is prolly a whole different ballgame and as you stated, its pretty well known about the voltage requirements. Not sure about the other Spektrum radios, but in my 9303 there is at least a warning now about it.

[brn2fly]

	Quote: Originally Posted by BoneDoc
	Who is to say that continuous hopping is optimal? What if the next two channel FASST hops on to is jammed? How dies it know where else to hop to?

It hops 500 times a second so jamming should not be an issue. Heck the military use a secure radio system that frequence hops too.

[sweetpea]

But anyone in the military will tell you that it isn't that reliable as far as getting your code to match everyone else so you can talk. (at least the version on my plane)

[brn2fly]

	Quote: Originally Posted by sweetpea
	But anyone in the military will tell you that it isn't that reliable as far as getting your code to match everyone else so you can talk. (at least the version on my plane)

If it's set up correctly it works fine, just a lot of stuff to get it working, BTW I PM you earlier. Looks like I will in Vegas Saturday and Sunday. What hobby shops are there here that deal with giant scale stuff.

[sweetpea]

Didn't see the PM......sending one back now

[XJet]

	Quote: Originally Posted by sweetpea
	So in a nutshell you have the companies learning from each other I'm very sure....... XPS...... Freq does not hop with sudden increase in noise floor past a certain threshold. --XPS states that this was because a sudden increase would typically cover the entire band so they software limited it not to hop

This is where JD and I differ in our opinions.

I've spent a *lot* of time looking at the 2.4GHz spectrum from an aerial perspective and I've seen far more instances of relatively narrow-band intense noise events than I have of all-encompassing noise sources.

Although JD says he's spent time analyzing the 2.4GHz spectrum, I think the experience that lead to the retrofitting of transmitter modules with an external dipole indicates that perhaps he's only done so from ground level -- and there's a *huge* difference. Unfortunately, it's in the air that things really matter most so ground-level observations (amidst the shielding effect of ground-clutter) are likely to have given him a bum-steer in this regard.

	Quote:
	--XPS has a software fix for this coming soon so it will hop no matter what

I certainly hope that "coming soon" in this case is a little faster than it has been for those 6-channel receivers and telemetry. :-) Let's hope that JD prioritizes this for the sake of his customers. I also wonder if the solution will be compromised because he doesn't want the hassle of having to "tens of thousands" of the XBeePro modules re-flashed -- at his own expense.

I wonder if this will be pitched as a "feature upgrade" that will carry a fee of some kind.

	Quote:
	--No independant testing has been done on gradual increase to date to verify it hops

Stay tuned :-)

Since I've now been offered a Spektrum and a FASST system to test, I'm in the process of working out how I can create a suitable test environment to put them all on trial. By subjecting them all to the same conditions, it should become very apparent which is most able to cope with a range of different scenarios in respect to noise-levels, interference, swamping, multi-pathing, etc.

	Quote:
	Spektrum......battery voltage issue... FASST...couple of lockouts I've read about but not much else... ASSAN and the other 2.4 companies....to new and not much reporting going on. They also... 72mhz....prone to all sorts of interference and the dreaded shootdowns. But a viable solution...

Today I had a few spare minutes so I threw a new set of (yet another, hitherto unknown) Chinese-made 2.4GHz RC gear into my Katana P profile. It was a very hasty install without much regard for the orientation and spacing of the receiver and satellite antennas (so hardly a really fair test), especially since it only attained a ground-range of 250 yards.

I flew the model and it was *very* loose with very noticeable latency on numerous occasions. What's more, it was the first time I've *ever* experienced glitching on 2.4GHz. Tomorrow I hope to get a chance to re-install the gear with a little more care and thus get a more realistic indication of how it is capable of truly performing.

This gear certainly is very cheap, I'm only hoping that it's not too "cheap".

Full details to follow.