Kiwi's XPS test results are up.

[porcupineace]

and like they say "-S#%@* happens" to everything.....just ask Boeing

[KrisW]

	Quote: Originally Posted by porcupineace
	and like they say "-S#%@* happens" to everything.....just ask Boeing

What happened with boeing?

[Woketman]

So Cherokee Jim: Found that report yet?

I did not think so!

[1bwana1]

	Quote: Originally Posted by Woketman
	So Cherokee Jim: Found that report yet? I did not think so!

Jim has already admitted in a round about way, that the report does not exists. See post 342 in this thread.

[madmax]

	Quote: Originally Posted by KrisW
	Sometimes I pity Maxxon. . then I remember that he actually did this to himself, and I just larf and larf. . .

Definitely self inflicted.

[spoiler]

	Quote: Originally Posted by porcupineace
	true ...an expensive hobby...and PROOF. hard to come by. and THIS IS an experimental hobby after all , isnt it?

It certainly is and I certainly am not advocating a culture of blaming our radio manufacturers for every problem we ever experience, then again, we need reliable equipment that will work properly when used within its design parameters which we should be made aware of. Thats where it seems to me XPS has failed dismally.

I crashed a plane due to pilot error recently. I have replaced it with the same airframe and have used all the old components. If my JR 10 ch Rx dies on my next flight I certainly wont be blaming JR.

[Gordito Volador]

	Quote: Originally Posted by spoiler
	I crashed a plane due to pilot error recently. I have replaced it with the same airframe and have used all the old components. If my JR 10 ch Rx dies on my next flight I certainly wont be blaming JR.

Yeah, I have had to fess up lately and admit pilot error on my part. Just can't yell out I got hit anymore.

Regards, Bill

[Reckless Loony]

Here is someone that states he has seen XPS hop and the conditions required.

http://www.rcgroups.com/forums/showp...0&postcount=89

He provides no video evidence also note his location which is Gilbert, Arizona and JD is in Havasu City, Arizona a mere 140 miles (225Km) straight line distance away.

JD’s statement as to what is required to make it hop

http://www.rcgroups.com/forums/showp...80&postcount=4

Tychoc’s video testing of XPS note that the 2nd video is with noise slowly rising on the frequency that XPS is on. It fails to hop.

http://www.rcgroups.com/forums/showthread.php?t=816989

In case anybody buys JD’s statement about you can’t bench test XPS here is a very memorable at field event that occurred in France

http://www.rcgroups.com/forums/showthread.php?t=730087

Read further and you find that at one time two XPS equipped heli’s crashed simultaneously. Also note that Futaba FASST doesn’t suffer from this problem. Note Spektrum not permitted in France.

The follow up

http://www.rcgroups.com/forums/showthread.php?t=738691

Note that it is in the XPS forum where JD is moderator and if you look at the bottom of the post “Last edited by JimDrew”.

This is just one of the early posts about XPS failure in the field.

http://www.rcgroups.com/forums/showthread.php?t=743841

Have a look at this

http://www.rcgroups.com/forums/showp...2&postcount=30

The transmitter maintains a noise table.

and then later

http://www.rcgroups.com/forums/showp...&postcount=119

The transmitter is dumb and tracks nothing.

Seems JD is confused as to how XPS works or rather he actually forgot his own BS.

Remember this link that I provided earlier

http://www.rcgroups.com/forums/showp...19&postcount=4

I won’t bother going into the error of his statements but instead note what he writes concerning the firmware.

And then

http://www.rcgroups.com/forums/showp...1&postcount=66

Note he is testing the new firmware

Oh look JD has come up with an excuse as to why the new firmware isn’t available

http://www.rcgroups.com/forums/showp...1&postcount=30

He now blames the FCC. He now needs to wait for clarification from them well that should buy JD some months for him to come up with some other excuse.

This is what JD wrote about 2.4Ghz video cameras

http://www.rcgroups.com/forums/showp...9&postcount=50

Take note of this bit

“If you activate the video camera prior to powering up our system, then our system will select a completely separate area of the band, furthest away from the noise generated by the video camera”

And this is the finding by Hcopter when he tries XPS with a 2.4Ghz video camera

http://www.rcgroups.com/forums/showp...&postcount=133

Note that it wasn’t until the third power up that XPS decided to hop away from the frequency that the video camera was on.

Don’t people think this may be one of the reason why the failure rate of XPS seems to have increased? Since now at the flying fields there are more 2.4Ghz sources than before and that it is a kind of a hit/miss for XPS to find a clean enough channel even during power up.

And just for comparison this is FHSS Futaba FASST system with a video camera next to it, which was posted elsewhere in this forum.

FASST Video.


The following is to do with “predictive frequency hopping” which is something JD also claimed.

http://www.rcgroups.com/forums/showpost.php?p=8784383&postcount=25

And from the XPS website

http://www.xtremepowersystems.net/xtremelink.php

The user manual for the Digi 2.4Ghz RF modules that JD uses

http://ftp1.digi.com/support/documen...5.4_v1.xAx.pdf

“predictive frequency hopping technique”

Predictive?? You mean those modules have crystal ball technology or is there a clairvoyant circuit? How the hell are you supposed to be able to predict when a 2.4Ghz device gets turned on and off?

Try this next time your at the flying field. Get a pad and pen and sit down in the pits. Watch your fellow modellers turn on their radios and note this down in the pad also note those that are turning off radios. Pretend all these radios are 2.4Ghz sets. Once you have made a nice list (a table) see if that helps you in determining (predicting) those that are about to turn on their radio next and those that are going to turn off their radio next. You will find it will be pretty much random unless of coarse it is close to lunch and then most club members will stop flying for the club lunch barbecue.

So how are these Digi 2.4Ghz modules able to read/monitor the noise level of the 2.4Ghz ISM band? Well on page 32 you can see the diagnostic commands.

You can use the DB command to find out the received signal strength.

Remember people these modules are designed for a PC RF networking (LAN) application therefore there would be a number of these RF modules communicating to each other. This then brings up the energy scan ED command. This is where the coordinator module (master module) initiates the other RF modules to send to it the signal strength value that they each have been receiving. Since these modules are being used in an RC application there is only two of these modules in use one in the Tx and the other in the Rx on the aircraft. Presumably there won’t be anybody trying to fly two or more aircraft at the same time using just the one Tx. Therefore the energy scan is completely useless in an RC application.

Back to the DB command the signal strength value returned is for the current channel the Tx and Rx modules are currently on. In order to establish what signal levels are on the other 12 channels it is therefore necessary to change channels in order to get signal strength readings for all channels not only that but it would have to be done continuously in order to continuously monitor the signal strength levels. This channel changing is accomplished by the CH (channel command) and AS (active scan) command. The coordinator (master) module sets the channel in the case of XPS it is the Rx (according to JD) and then the Tx has to find it using the AS command. The problem is active scan takes a bloody long time to do. Page 51 gives the equation as well as the duration of time it takes. Do note that AS is used in conjunction with the SD (scan duration) command. If SD is set for the minimum value there is a good chance the Tx will fail to find the Rx especially if the noise level is getting high. It should be pointed out that while the modules are in command mode there is no data flow in other words the Tx is no longer transmitting stick data to the Rx. Even if SD is set to 0 the time taken to perform the scan is 180ms which means at least 9 lost frames of data which will be noticed when your flying your aircraft.

To better understand by what I mean by 9 lost frames here is what the PPM data stream being fed to the RF module looks like.

http://www.mp.ttu.ee/risto/rc/electronics/pctorc.htm

Thus 180ms divided by 20ms = 9 lost frames which is the best-case scenario.

JD has stated that the modules wont switch frequency until necessary and this is the reason why. You can’t have the modules hopping about the channels in order to monitor the signal level of the other channels because you would be losing at least 9 frames of data every time they changed channels, which would make for crappy control of the aircraft.

Therefore this proves that the statement “predictive frequency hopping technique” is a load of crap.

BTW page 20 of the manual describes the 5 modes of operation of the modules and how they are entered into.

I posted about the predictive hopping stuff on Rcuniverse I also did a less technical follow up.

http://www.rcuniverse.com/forum/fb.asp?m=7461845


Here you go XPS is closed as JD and sidekick go on tour.

http://www.xtremepowersystems.net

You think that JD would be busy working on products he stated he was going to release such as the Telemetry that was announced way back here.

http://www.rcuniverse.com/forum/fb.asp?m=4715364

June, 2006 he even gave a price of $129 for a product that didn’t exist. Some 23 months later and counting there is still no telemetry. And then there is the hopping video.

http://www.rcgroups.com/forums/showp...&postcount=298

http://www.rcgroups.com/forums/showp...&postcount=310

Now May and still no video.


And to give you an idea how great JD is as a programmer

http://www.rcgroups.com/forums/showp...&postcount=394

http://www.rcgroups.com/forums/showp...&postcount=396

I tried it myself and got

http://i5.photobucket.com/albums/y19...1/xpsorder.jpg

and a little later note the date

http://i5.photobucket.com/albums/y19.../xpsorder2.jpg

[jonkoppisch]

Oh Boy... snake oil for sale at Joe Nall...

[Simpleton]

I can't imagine him showing up there, but I've been wrong before. At least all his dissatisfied customers would have a chance to say what was on their mind without him being able to ignore it.

[jonkoppisch]

Not only is he showing up....

"

Xtreme Power Systems hits the road!

Online ordering closed from May 8th through May 20th

The crew at Xtreme Power Systems will be traveling to the Joe Nall event in South Carolina, from May 8th through May 20th. We will be closing our online ordering until we return! We will have our custom show trailer and 6 booths at the Joe Nall event. Graupner pilots from Germany will be flying in to do demos along with the XPS pilots. We will have product on hand for sale, including our Lipo batteries, Graupner Booster turbines, and of course our XtremeLink radio systems. Note: all orders placed up to and including May 8th will be shipped before we leave.

"

[Simpleton]

That's just what's posted on his website, I was under the impression that was not always a source for factual information. They could have a few blowouts, engine trouble, car-jacking...any number of reasons why they didn't make it.