Independent tests prove lack of frequency hopping with XPS

[Simpleton]

	Quote: Originally Posted by Pale Rider
	Thats an interesting comment. Can you show the data that would corroborate this ?

I think he was talking about his own experiences. I don't know about him, but I don't log every glitch or twitch I ever had so I can have data to back up my glitches and twitches. YMMV.

[Pale Rider]

	Quote: Originally Posted by Simpleton
	I think he was talking about his own experiences. I don't know about him, but I don't log every glitch or twitch I ever had so I can have data to back up my glitches and twitches. YMMV.

Ok--I re-read it and saw he was speaking of his own flights..

[Toumal]

	Quote: Originally Posted by XJet
	Nope, I'm 100% right! I've been in the software industry for over 30 years and I often hear *programmers* say "I can write faster than that" -- until you sit down with them and show them how very few lines they actually write per day when amortized across the entire development cycle.

I'm a full-time software developer myself, developing ground systems for air traffic control. IMHO XJet is right when he says that millions of lines of code sounds very exaggerated, and that writing lots of code is no indicator for quality - in fact, quite the contrary. Software developers who believe that are often seen coding away from day one, whereas the experienced developer starts with his design while drinking a cup of coffee. Most often, he will be the last to have the first version running, but at the end he'll be the first to have it passing all tests.

	Quote: Originally Posted by skubacb
	Spherical coverage is just that. We are not talking about the antenna pattern which indeed does seem to have a dimple. At the first AMA convention where JD talked about the system he stated that there was a dimple. I worked antenna patterns and coverage in my AF operational testing and a dimple is not necessarily a dead spot. The RX may allow a DB level low enough that you do indeed have spherical reception. Thus is is NOT at all magical.

Oh certainly, you will still receive something. But the question is how much.
This is the pattern of a 1.5GHz monopole antenna:





I'd say the dimple is rather significant, and it only gets worse with higher frequencies.

Also, at the end of the day it doesn't matter if it's "just marketing". If a car maker claims that his airbags are enough to eliminate the risk of a frontal crash at 40mph, and it turns out that parts of the engine compartment cut off your legs at a crash test, it's still a lie.

The Graupner website says this: "Approximately spherical RF radiation pattern; no multi-element aerials required"

Well, there's a joke in mathematics: "In first approximation, a cow is a spherical object that emits equal amounts of milk in all directions."

[grayuk]

	Quote: Originally Posted by Toumal
	Well, there's a joke in mathematics: "In first approximation, a cow is a spherical object that emits equal amounts of milk in all directions."

LOL

[Dustflyer]

Wow! It blows my mind to hear of anyone still flying XPS in a valuable airplane. I just sold my 33% H9 Cap to a fella who just crashed his. He said he was on final and it just dropped a wing and went in. The discussion turned to radios and it came out that he was flying it on XPS!. When I found that out I asked if he was familiar with these forum discussions. He wasn't. Just for grins I showed him my videos of XPS glitching and failures and it blew his mind, I mean really blew his mind!

"Wow" he said shaking his head, "maybe that's why my Cap used to do all that weird stuff! Every now and then it would just do something like this (makes hard pitching and banking hand motions)."

How about that?

Here's a video you'll love. I thought I had accidently deleted this but found about 6 seconds worth of a great XPS video. When I first got my XPS system I hooked it up to a freshly charged battery pack and Futaba 9303 servo. It started doing weird stuff right away. Everytime I turned it on it did something strange so I made up a big orange pointer for the servo and took this video. It just sat there and did this over and over for minutes at a time. The video is quick so don't blink!

[skubacb]

Interesting video. Considering I have over 20 XPS RX and two TX modules, I have never seen this. Might even have been the servo which I have seen do this with just a servo tester.

Second if there was a problem with XPS it has a life time warranty and he sends you a new unit.

Had a guy here get back a unit he sent into Futaba. They sent a bad unit back and because he forgot to test it in a cheap aircraft he lost a $7000 aircraft. Point: Futaba does send back the same units. Hitec did the same thing to me except I did some testing before using itl

People have lost planes with Spectrum and Futaba 2.4 ghz systems and are still doing so. So lets be straight. I figure if anyone is concentrating just on just one system they have an agenda.

Toumal: Duh of course you have a variation in the reception level at the RX. That was the whole point. We are talking coverage not a characterized antenna pattern which is normally done at -3db. I don't know where you decided that the dimple was significant since the Boeing engineers that tested XPS said it was not. It still doesn't matter spherical coverage is still spherical coverage even if you want to call it a cow.

[Mark Davis]

	Quote: Originally Posted by XJet
	It's interesting to note that JD is now claiming he's written "millions of lines of code" during his software career. This makes him a true God amongst men, since the industry-standard productivity for a good programmer when presented over the entire development cycle of a product is a mere 5-7 lines of code per hour.

Xjet, you obviously are believing some Gartner Group statistics... Which are BS, much like this thread... I have teams of developers working for me and I can guarantee you that if any of my people were only producing 5 - 7 lines of code an hour, they would be looking for a new profession... Period...

Don't you people have anything better to do than to drag this thread out infinitum???

[Toumal]

	Quote: Originally Posted by skubacb
	People have lost planes with Spectrum and Futaba 2.4 ghz systems and are still doing so. So lets be straight. I figure if anyone is concentrating just on just one system they have an agenda. ..... Second if there was a problem with XPS it has a life time warranty and he sends you a new unit.

*sigh* And what are the exact numbers? And were these losses really caused by the radio link? You know, we've been going over these arguments before. It would be helpful if you would read the other XPS thread *before* you bring up the same arguments again. Regardless of whether XPS or something else, if someone falls from the sky you can't just point fingers. Not unless there's proof as to the cause of the accident. I don't count the "I flew XPS and I fell down"-reports against XPS, because that's to be taken with a huge pile of salt. But hey, even if you do believe every single crash report you hear, let's count the alleged XPS, FASST and Spektrum crashes.



And as for the lifetime warranty - we're talking about design issues here. I don't have an agenda, but answers like that one make me curious about yours.

	Quote: Originally Posted by skubacb
	Toumal: Duh of course you have a variation in the reception level at the RX. That was the whole point. We are talking coverage not a characterized antenna pattern which is normally done at -3db.

How is it "done at -3db"? I'm talking about antenna gain. Yes you have 360 coverage in all directions, but you will suffer from a serious loss if the RX antenna points straight at the TX. Is it enough to make you fall down? Doesn't have to be, but under adverse circumstances (long distance, some form of obstruction, humid weather) it can be. It's rather easy to test this in real life too, do a range check with both antennas pointing at each other. (okay so that would be an approximation again because there will be reflections from the ground...)

	Quote: Originally Posted by skubacb
	I don't know where you decided that the dimple was significant since the Boeing engineers that tested XPS said it was not. It still doesn't matter spherical coverage is still spherical coverage even if you want to call it a cow.

I want to see that test report. Otherwise this is just Proof by Inaccessible Literature ( http://www.maths.uwa.edu.au/~berwin/...ibleliterature )

[RH1N0]

Do
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Writing code is easy - how many million lines would you like

[Dustflyer]

	Quote: Originally Posted by skubacb
	Interesting video. Considering I have over 20 XPS RX and two TX modules, I have never seen this. Might even have been the servo which I have seen do this with just a servo tester.

Servo in perfect working order, works perfectly with other receivers etc. Battery checked to full discharge capacity, freshly charged. Transmitter in perfect working order, just back from full checkout from Hobby Services, declared in perfect working order. Pots new, changed anyway as a precaution. Transmitter works perfectly with Spektrum module.

Bucket loads of crashes with XPS. Evidence of faultiness and unreliability now overwhelming and indisputible. Fully documented with videos, crashed airplanes, valid tests.

But... If XPS is working for you and you are willing to risk your airplanes with it I say more power to you. Enjoy it and thanks for your input!

[Woketman]

	Quote: Originally Posted by Dustflyer
	But... If XPS is working for you and you are willing to risk your airplanes with it I say more power to you. Enjoy it and thanks for your input!

NO THANKS!!! XPS is well documented to be FAR too risky for use in anything you care about. It is a "foamie only" radio system. Just wish I had known this BEFORE I wasted $$$ on it!

[Kiwi]

**Kiwi, at least you understand the limitations of your testing as some others do not. It was not a test to see if XPS would hop since you did not have the parameters under which it would hop.**

Seriously your pulling my leg with that statement right.??

That test proves beyond all doubt that XPS does not hop in any form or manner that would be of any use to an average modeler. More so no one has ever, that is never ever been able to produces a video or any form of evidence that XPS hops.

I dont doubt that under very special circumstances, that can only be created in a laboratory, that XPS could be made to hop.

But we dont fly in a laboratory do we??

XPS works, thats a fact, but it has no frequency agility or ability to withstand sudden bursts of interference and the other two systems do manage to fly through that. Thats all I was looking for.

Is it true the XPS system does as advertised? and the answer to that is no, not in a reliable manner that would be of any reasonable use to an RC airplane pilot.

Currently I know of three new systems being developed that will raise the bar significantly for the 2.4 Ghz system. However they are new and I am not about to get into the prototype free marketing and BS business. When they hit the market we will see. As my Mum says, the prove of the pudding is in the eating. Until then I know nothing.

[JEFFRO503]

AARRGG!! man , i just don't get it! the fan boys of XPS still come on here to defend something that has proven time and time again....IT DOES NOT HOP!!! IT DOES NOT HOP!! IT DOES NOT HOP !! Do we need to say this again....and if so , how many times would like to hear it , before you believe it?? I think you guys keep asking the same stupid question over and over and over , hoping that the answer will change........IT WON'T!!


sheeeesh man......All you guys that keep stating that you "THINK" XPS hops.....Get off your ass and prove it! Kiwi and XJET have proven time and time again that it does not hop.

Quit stating BS statements saying it hops. prove it or shut the hell up please!

excuse me for a while , i'm going out to my garage to slam my head through a wall from the frustrations of this thread and the XPS defenders.

[Woketman]

	Quote: Originally Posted by JEFFRO503
	Quit stating BS statements saying it hops. prove it or shut the hell up please! excuse me for a while , i'm going out to my garage to slam my head through a wall from the frustrations of this thread and the XPS defenders.

Yeah Jeff, the XPS FanBoys are just that: boys that cannot accept the fact that they chose a crappy system that the manufacturer lied to them about.

Oh well, some people just don't wanna hear the truth!

[capgains]

	Quote: Originally Posted by Woketman
	Yeah Jeff, the XPS FanBoys are just that: boys that cannot accept the fact that they chose a crappy system that the manufacturer lied to them about. Oh well, some people just don't wanna hear the truth!

What the hell is a FanBoy?