Independent tests prove lack of frequency hopping with XPS

[sweetpea]

	Quote: Originally Posted by Kiwi
	Sweetpea. Your a very defensive young guy and I admire your tenacity. When I said XPS is still the same box as it was two years ago I meant that fundamentally the OS is the same. The XPD is a bell and the new cases are a whistle. But the guts of the device, the spherical nuclear all encompassing antenna etc are the exact same. The one and only issue with XPS that I see from a user point of view is that it is a single locked channel system with no antenna diversity, no possible way in the world to dodge interference or skirt it somehow. The other systems (ASSAN is the exception but they dont claim to hop or try to get out od the way) ALL HAVE DIVERSITY. If XPS would do what the manufacturer says it can do and show with repeatable certainty that it is a flexible and agile 2.4 Ghz radio transmission device perfectly suitable for RC use in all types and sizes of model airplanes then I will take my hat off to JD and the company. Competition is great, it drives technology, it creates a buyers market and normally it gets the customer a better deal in the end. But sometimes there are people who sell little bottles of snake oil at exorbitant prices claiming to cure anything and everything when in fact the oil in the bottle is for frying turkeys in. As for testing the resistance of the others to the same test I have done it a dozen times but what I cant do is soak the entire band with sufficient noise to make even the slightest impact. I dont want to spend another $500 on the jammer as that is just wasting my money on a ten minute show and tell and then what will use it for?? Sort of a dumb device to be carrying around in my RC box I think. So if your willing to let me show you FASST and SPEKTRUM working in the exact same conditions as I tested XPS I will post the video for you. But realize that with a single channel Rx (XPS) I will make it go into fail safe. The others will work perfectly because in the case of SPEKTRUM it has the second channel miles away from where I can swamp it and FASST just passes through it as if it does not exist. I will try my best to get the video done tonight and post it for you.

Just for the record....Spektrum and FASST haven't done anything more fancy than XPS in regards to upgrades.

Spektrum--under the table upgrade that changed how it looked for freqs when a brown out occurred. Did nothing to stop the brown out or decrease its value. If it wasn't for the R/C forums no one would know you could do it.

FASST--Out in the open (good job there) they will reset your radio off the Zguid but that is still clouded in whether or not its a perm fix. You have other countries getting a different version of the fix than the US. Which is better or correct?

I would definetaly say that of these 3 manufactures that non of them has done a superb job of fixing their own issues.


As for your tests Kiwi........don't buy more equipment. Just post the vid of you doing the same thing you did to XPS to the others. so that would mean putting Spektrum on and putting the same power on one freq. Then slowly bringing it up and from the side etc. Then doing it again to the other freq it uses. For FASST I would just pick a freq in the front, middle, and end of the spektrum and do the same thing.

I expected these 2 to pass, but wanted you do it just to make sure that there wasn't something intrinsic in the test that may cause all to fail. Posting the video seals the deal just like everyone says it does with XPS.

[pilot232]

To Cherokee Jim,

I own a Multiplex mc4000. I converted it to Spektrum with help from Paul Beard. Nine chanels and it works beautifully. Take the following link if you are interested.
I used to fly XPS but was not comfortable with the lack of antenna diversity or apparent lack of frequency aagility.

Link: http://www.rcgroups.com/forums/showt...c4000+spektrum

Warm Regards,

Travis

[Kiwi]

Sweetpea,



Just back in from my shop and I finally got everything you want to see done. I have the video but will do one or two minutes shoot tomorrow to show you what happens.

Rather than leave you hanging by the neck however here is what took place and the results.

Tonight I set up four different radios.

Spektrum 7
Futaba 8UAPs with XPS
Futaba 8UAPs with Assan
Futaba 8UAPS with TM7 FASST module

Plus I ran my 14MZ on 2.4 to help create more noise.

Noise was generated using the AIRHORN from http://www.nutsaboutnets.com/ and it was generated in pulse mode and fixed.

The scanner was the Wi-Spy from http://www.metageek.net/.

XPS base line test. ( I needed something to set a goal)

OK first off I set the fail safe on the XPS so I could see it react as opposed to last time just waiting for it to fail. This time running just the XPS with the airhorn sending 5 seconds bursts over the 11 WiFi channels XPS went straight into lockout, it did not failsafe. It just froze up until the scanner had moved at least three channels away from the selected channel then it came back to life again. Pretty much what happened last time but just a little more conclusive.

ASSAN

Set up the same parameters as the XPS and same results. ASSAN locked up instantly there was strong noise on its chosen channel and it performed exactly as did XPS.

SPEKTRUM.

Same tests as above with the noise being generated over the spectrum. No noticeable impact of the controls so I added a video camera signal and turned on every other radio system I had. That is there were two FASST systems running, XPS and ASSAN. Spektrum never took a hit or showed the slightest evidence of any signal corruption. The video signal chosen exactly overlapped one of the SPEKTRUM channels as well so it was taking a serious beating. Nothing happened. 100% did not glitch or move.

FASST

Same scenario as the first XPS test. Unit was the TM7 transmitter module and 607FS receiver. Again the scanner showed it moving rapidly and using every nook and cranny in the spectrum. I subjected it to the all radios on test, video transmitter, and airhorn. I turned the radio on and off and it reconnected but I would not do this as a test at the field. It did not hook up at a pace that would save your butt. FASST behaved exactly as did SPEKTRUM. Solid, no glitches, nothing untoward at all.


Conclusions.

The conclusion and I'm not testing this stuff anymore is that ASSAN and XPS while seriously different vegetables perform about the same. They both failed and lost communication in seriously noisy environments. They both did not go into fail safe but locked out instead. Now that could possibly be a fault of the tester not setting the system up right. I admit that could be a fault but when I turn the radio off the servos went to low throttle were I had them set. With the noise they just locked up.

Now these conditions were horrendous for any radio system to survive but FASST and SPEKTRUM did and there was no glitching, no jerky servo movement. Plain fact is unless you had the scanner you would have thought they were in clean air.

The videos will take a while to cut and render as its a very long process. I use a SONY digital HDD 1080i camera and I have to change that format off the camera to give me an editable format for the MAC. A five minute video takes me about two hours to convert and render in a format you guys can see clearly.

However for my own peace of mind I can absolutely prove to one and all that ASSAN and XPS wont work in a noisy environment. I can prove that I cannot make FASST or SPEKTRUM fail in the exact same conditions as the previous two failed in.

I know what I will fit in my planes if and when I go to 2.4Ghz. There are two good choices so far. I'm sure more are coming like the Weatronics and the AIRTRONICS.

I'm working on the vids guys as fast or is that as FASST as I can. But its done, I'm happy the results were repeatable time after time. This was not luck or a flook. What I got in the end was real.

[1bwana1]

Very good information Kiwi. Thanks for all of your efforts, you have done the RC community a service.

[sweetpea]

Thanks---glad the results were as predicted

[ricoalonso]

Kiwi,
Thanks for sharing the result. Very Good informations.

Edit: I just noticed... it went into 'lockout' instead of failsafe? Now that's even getting worst. First the 'hopping' is proven not working... now, even the failsafe is no use?

^R^

[XJet]

It seems a if those who were labeled as "no-nothing, self-appointed experts" were right (yet again).

However, I have strong doubts that even this evidence will shake the faith of those who still believe everything that XPS tells them.

Still, for the rest of the world, who have the ability to judge issues on the facts, the results are proof that XPS is indeed a perfectly adequate second-tier 2.4GHz system which works slightly better than a budget Chinese 2.4GHz set (Assan) costing a fraction the price.

[ASSAN]

TO:KIWI

Dear kiwi, thanks for your test report.

one information i need meation that is we have been update the version since 1th,Feb 2008.

i hope you can use our new version to test it again.

in my test in lab, if the powerful noise(such as 500mw 2.4G video Tx )nearby our Rx (10cm) and worked in the same ch.the control range will shorted to about 20 meters.

but it's has been improved more than your test samples'.

thank you.

meng

[buttface]

Kiwi, You are the man!
Your test results for XPS mimic what happened to me in my 40% Extra.
My ignition had developed a bad coil in flight causing the XPS to go into lock out.The surfaces froze in position extreme 3D throws (Fail safe did not come on)The plane was heading for a busy housing development as the wind carried it while falling.
I recovered the plane after it fell 200 ft. (good thing it was up high setting up for a blender.The surfaces kept freezing up as I glided in to the runway.I am glad no one got hurt or killed.

[Four Stroker]

Well buttface, that can't possibly be true. Paul Beard assured us that 2.4 GHz is well above any noise that you could get from your ignition.

[buttface]

	Quote: Originally Posted by Four Stroker
	Well buttface, that can't possibly be true. Paul Beard assured us that 2.4 GHz is well above any noise that you could get from your ignition.

It is true.DA confirmed the ignition had a bad coil.The XPS worked great for the 50 flights before the ignition went bad and the motor started misfiring.XPS simply could not hop past the noise.
You shouldn't believe everything Paul Beard says.Shame on YOU!

[JimC-MD]

Generated RF noise from ignition components is not the same animal as transient voltage spikes. A bad coil could have been firing externally. You have no idea where that would go. All it would take is one wire or component close enough to the ignition module or even the shielded wires to cause an issue. The bad could could have been firing to the case and therefore "Charging" the webbing on the outside of the ignition cables. Any radio would be whacked by that.

The thing to remember is to keep ALL ignition components separated from any gear hooked directly to the radio. I would suggest at least two inches. The reason for that would be to eliminate any chance of an actual spark jumping to a radio component and then traveling to the radio.

The material that components are mounted to should be an issue as well. Light ply would not be an issue. Some of the "bling" materials like CF or the aluminum look composite materials could make it the same as wrapping them all together.

So, ButtFace. You guys are both correct. The "noise" that is related to normal ignition operation is not of a frequency level that would effect reception of a signal. Take one of your spark plug wires and tape it to your RX and watch it dance. See the difference?