Independent tests prove lack of frequency hopping with XPS

[sweetpea]

Looking forward to the same round of testing against both Spektrum/Fasst/ASSAN.

its getting interesting now!

[Eflyer_75214]

It would be much more interesting if Jim would simply have a 3rd party such as a University or a lab test the system to show that it does or doesn't hop. Basically, put up or shut up. Would make his existing users much more comfortable if they can show it hops and stop the detractors.

Ron

[sweetpea]

In his "Sticky" he put up with his answer to the recent threads he mentioned conditions that would make it hop.

"Does it hop? Yes, it does. Can you make it hop? Probably, but it is going to require some very specific situations for it to occur.

The hopping is predictive, based on the noise floor over a period of time. When the noise increases at a particular rate and pattern, a new frequency can be selected. Can be? Yes, if there are no good frequencies to use, hopping can be more of a problem than not hopping.

So, how did we determine the noise rate and pattern? By flight testing at various locations, including Las Vegas - which we believe has the highest noise floor in the U.S."


I simply asked......."I think this is what most of the so called experts want explained. They want to know the rate and pattern."

It remains unanswered. I for one don't care to see his tests of it hopping. Just explain what conditions are required....plain and simple.

[Daemon]

The problem with the question of "what do the other systems do" is that
we already know what they do with respect to hopping. Spektrum doesn't claim to hop,
(or at least it never moves from the two frequencies it chose at startup)
and FASST hops constantly whether it's needed or not.

One thing not mentioned in the preceding series of tests is how XPS responded
to all this noise? Did you have a link the whole time, or did it lose the link and
drop to failsafe?

I ask because obviously if it maintained the link through all your tests without
going to failsafe, then JD would just say "it's so good that it doesn't' need to hop". Of
course I've knocked it into failsafe about 40 times in the last 24 hours, testing
with my 2.4Ghz video Tx, but I'm curious if your noise generator is doing
that or not.

I think what everyone else is asking for now is a test of responsiveness.
XPS, Spektrum, FASST all running at once, and then run the same series
of noise generation tests across the whole spectrum and see how each system
responds. Loss of link, sluggish response, or completely normal.

BTW, the test you didn't do that, Jim claimed would induce hopping, is
a gradual rise of the noise floor to the point where it does harm to the link,
followed by a small decrease. I think the logic being, that it needs to know it's
in harm's way, but still be able to tell the Tx that it needs to move.

ian

[buttface]

	Quote: Originally Posted by XJet
	Well I"m just trying to throw JD a lifeline here. Obviously, no matter what I, Kiwi or anyone else says in respect to XPS, JD's happy to simply reply by saying "it hops" and then it becomes a "he-says, she-says" situation that likely leaves a lot of people unsure who to believe. If a truly independent testing organisation gets involved, the whole debate over antennas, hopping etc becomes finalized and we'll have something solid to go on. It strikes me that this is by far and away the simplest solution to a complex and important problem. Or do I have this all wrong?

It is apparent that you are NOT bashing JD,how ever hard it must be!And YES we just want some good solid proof.Role in the independent testing organization !!!!I think we deserve some solid proof!You are on the right track Bro! You make sense to me!

[Daemon]

On a side note, JD and others familiar with the Xbee modules have stated that the Rx
drives the whole channel selection process. It's not looking for the Tx at all. It scans for a
channel with a low noise floor at startup and then sits there transmitting "Hi, I'm on
channel X bound to Tx Y, come find me". When Tx Y is turned on, it just scans through all
the channels looking for the Rx sending the message that matches its GUID (really the MAC
of the Xbee module). If you turn the Tx on before the Rx, then the Tx just goes into
perpetual search mode, until the Rx is turned on, does it's own channel scan, selects a
free channel and starts broadcasting its message for the Tx to find.

Could be interesting to see what happens on the spectrum when you turn the XPS Tx
on without the Rx.
Do you see it transmit at all?

ian

[buttface]

	Quote: Originally Posted by Daemon
	On a side note, JD and others familiar with the Xbee modules have stated that the Rx drives the whole channel selection process. It's not looking for the Tx at all. It scans for a channel with a low noise floor at startup and then sits there transmitting "Hi, I'm on channel X bound to Tx Y, come find me". When Tx Y is turned on, it just scans through all the channels looking for the Rx sending the message that matches its GUID (really the MAC of the Xbee module). If you turn the Tx on before the Rx, then the Tx just goes into perpetual search mode, until the Rx is turned on, does it's own channel scan, selects a free channel and starts broadcasting its message. Could be interesting to see what happens on the spectrum when you turn the XPS Tx on without the Rx. Do you see it transmit at all? ian

\

50% of the time my XPS would not connect upon turning it on and I would have to turn it off and back on again. Why dose that happen?When you turn on the FASST "ITS ON!" (pun unintended) lol

[Flatlandman]

Kiwi, why did you not turn on a futaba fassst system to see the results or any other system. The one confirmation to the hop supposedly came from the fasst system. Theres to much assuming in these tests (all of them not pointing at Kiwi's test on this); I read to many statements like "that should do it" almost like they're trying to be right and not so much get it right. I just want to see some info that proves it doesn't hop and what we're getting so far is it doesn't hop in these 3 situations. For me this myth isn't busted just yet although I'm still very very concerned.

[buttface]

I think all XPS equipment should be grounded by the AMA until it has been proven safe.

[wrightme]

This looks like the XPS did not even attempt to hop with this setup. To add to the data, did you also see what the status of the link state was?
i.e., did the TX/RX remain linked, decrease control sensitivity, or lock-out going in to failsafe, or cease responding without entering failsafe?


Nice spectrum analyzer equipment it looks like.

Also, it is worth noting that the FASST antenna touch MIGHT have caused a lasting problem with the RX in that "supposed induced hop" test. (if I read the information correctly).

	Quote: Originally Posted by Kiwi
	Well that about does me on XPS folks. I will not say it does not hop channels as there may be a way that it can. But so far I have: Raised the noise floor slowly Pulsed on the same channel Drowned it with interference And none of those scenarios causes XPS to swap to a cleaner channel. SO what's my verdict. If XPS hops channels then please someone show us on this site and in this thread how, why when and where because I cannot force it to do so, no one else has been successful in doing so. I'm buggered if I know how. I'm out of ideas and scenarios. I personally would not use this system until its proven. XPS cannot be made to HOP under reasonable test conditions and circumstances that should force a frequency change. So after all that I turned off the sig gen and yes sir. XPS was still happily firing away on channel 11. No thank you.

Edit: Question. Do you have the firmware versions for the units under test? May not make a difference, but doesn't hurt to know.

[bgold]

Kiwi: Did or will the the radio continue to work during your tests and if it fails or goes to failsafe at what level does that occur and is it same or different under the different tests you performed. Thanks
Bill

[sweetpea]

	Quote: Originally Posted by buttface
	I think all XPS equipment should be grounded by the AMA until it has been proven safe.

Then ASSAN and several other one freq brands of 2.4 need to be banned as well.