Kiwi's XPS test results are up.

[treb63]

Hi,
I think I can clear this up a little, Channel information on the XPD analyzer programme may not relate directly to the actual channel asignement in use only a full view of the frequencys in steps which looks like channels available (my mistake)

However it did jump from the 10th step to the 20th step then which was a frequency jump which may have been enough to be a channel jump?
I am informed that the display shows a range of 0-90 in steps of 5 showing the entire ism band.

[ricoalonso]

treb63,
Thanks for clarifying that part.

Rico.

[Four Stroker]

802.15.4 channels are 5 MHz wide. They do not agree with the usual 1.023 MHz reference channels.

[USN_POPS]

I sent an email to XPS tech support to see if there was validity in this set of test results. These negative posts about XPS is causing some problems at the field. People see what I am using and think it is unsafe after reading all the bad press in these forums. So I asked for clarification. Within 12 hours I received this response:

"We have not seen the video. We can't access the flying giants site
apparently. Obviously we know it hops and it has been demonstrated by a
few others already. We have also demonstrated this to the powers that
be (AMA, MAAA, Graupner, etc.) so we have never been concerned about
someone not being able to make it hop using bench test equipment. We
don't fly our planes sitting on a bench.

We have stated before that our system uses a predictive hopping scheme.
The only time our it hops is when the noise floor is rising/falling in
a predicted pattern, long before any type of potential problem occurs.
The idea behind this is to increase the range. Less noise = longer
range. As stated repeatedly, REAL WORLD tests clearly show that when a
single frequency on 2.4HGz is saturated, the entire band is also
saturated. It does no good to hop when there is clearly no place to hop.

However, to make the masses all warm and fuzzy, we are making a small
change to the firmware that allows the system to hop during a fail-safe
condition *if* there is actually an available frequency. So, people can
perform their bench tests and easily see the change (and feel happy).
In reality, the only time we have ever seen a case where this is needed
is when a high power 2.4GHz video transmitter is being used directly
next to the receiver (and is turned on after our system is turned on).
You can also completely lock out a Spektrum system using two video
transmitters next to their receiver. It needs to be clear that bench
test conditions do NOT replicate the reality we have at our flying
fields or in the air. We have traveled the country monitoring the
2.4GHz band, and there are simply no locations where a single frequency
is turned on randomly, and with enough power to effect our system.
Interference either occurs across the entire band and causes a problem,
or does not cause a problem at all. In every case we have seen, ISM
devices always co-exist, even on the exact same frequency. It is
required under FCC/IC/ETSI rules to co-exist. Non-ISM devices do not
have this requirement. Non-ISM devices would be video transmitters and
radar. Video transmitters can only affect our system in the direct
vicinity. Radar saturates the entire band, so it kills ALL 2.4GHz
systems, including those that use true frequency hopping.

Our system is the only system that uses bi-directional communications to
immediately re-send data that is lost. All other systems require that
they wait for the next frame. It is certainly possible to have many
frames coincide with bad data and thus you lose complete control during
this time. With our system, you don't. That's easy enough to "bench
test" as well.

We do have to say that our competition is doing a great job of stirring
up things. We appreciate the extra attention we are getting.



You are welcome to post this information to the flying giants website."

And here it is - straight from the horses mouth. Do we fly airplanes or just sit around doing bench tests. For me it's in the flying that proves the system.

[gareth.ky]

No one has yet shown how the FASST "avoidance" feature works. They claim is will avoid channels with interference but we have yet to see it do that. I suspect it will be very hard to do so. Its transmissions are so short compared to the other noise on the channel its going to be hard to see if it is in fact still using that frequency when noise is introduced. That is one aspect that is worth investigating.

I would also like to know the power output level of the frequency hopping vs. frequency locked devices?

I suppose we should test to failure. What does it take to break the link for XPS, Spektrum and FASST? How likely are those things to happen in the real world outside the lab where devices actually have to obey the 2.4Ghz band rules?

[cptsnoopy]

Hi Kiwi,

Thank you for posting your tests. I missed something in the video that may just be assumed. Did the XPS system become sluggish or stop operating during the tests that you videoed?
Another thing I wanted to offer is that the Evo-12 radio is just over 8 volts fully charged and I have had zero issues with the XPS system down to 7.4 volts. ( I have not tried using the Tx at a lower voltage) Since the radios that use an 8cell NiCD or NiMH battery are of a different brand this may not mean anything...

I enjoy both my XPS and Spectrum radios with the exception that the Evo-12 adds another dimension to the sport.

[Flyfalcons]

Dick, I got the chance to fly Jeffrey's Extra and for a second when he first handed over the transmitter I could have sworn it locked out on me. It might have just been his setup but I felt that I gave plenty of control input and the plane didn't respond. I gave the transmitter back and let him finish the flight. Later I got another chance to fly it and didn't notice any control problems.

[XJet]

	Quote: Originally Posted by gareth.ky
	No one has yet shown how the FASST "avoidance" feature works. They claim is will avoid channels with interference but we have yet to see it do that.

I doubt that FASST "avoids" channels with high noise levels -- it's far more likely to work on the basis that it knows data sent on noisy channels may be lost -- but since it's (pseudo)randomly hopping, the actual effect the occasional (random) lost packet will have on control is imperceptible.

Of course if half the band was noisy (must unlikely) the latency would double -- but since the data rate is probably higher than your average PPM/PCM set anyway, even this probably wouldn't be noticeable to the average flier.

In a way, the FASST system will respond to severe interference in the most desirable way -- by gradually showing increasing latency in control response.

By comparison, the XPS (assuming it is unable to hop) will simply go into lockout and the Spektrum will do likewise (if both channels are hit).

So in effect, the FASST system *should* be the most interference-resistant and safest 2.4GHz system. I say "safest" because those flying FASST will start to get some indication something is wrong long before it locks out. If even *one* of its channels is clear enough for the data to get through, you should retain some semblance of control with the Futaba system.

It only takes two channels (if they're the two your using) for Spektrum to get knocked out, and just *one* for XPS to go belly-up.

They all work -- it's just a matter of which provides the most safety margin in terms of handling interference and I'm putting my money on the order of resilience being: Futaba, Spektrum, with XPS coming a distant last -- only a little better than the likes of ASSAN and iMax.

[KrisW]

	Quote: Originally Posted by treb63
	Hi, I think I can clear this up a little, Channel information on the XPD analyzer programme may not relate directly to the actual channel asignement in use only a full view of the frequencys in steps which looks like channels available (my mistake) However it did jump from the 10th step to the 20th step then which was a frequency jump which may have been enough to be a channel jump? I am informed that the display shows a range of 0-90 in steps of 5 showing the entire ism band.

Soooo .. .perhaps the "channel 10" you were speaking about is actually Channel 1 for XPS, and the channel 20 is actually channel 2 for XPS. XPS tends to default to channel 1, or so it appears, so a reboot puts you back at channel "10" unless the channel was blocked during reboot.

[KrisW]

	Quote: Originally Posted by RichardCorby
	I sent an email to XPS tech support to see if there was validity in this set of test results. These negative posts about XPS is causing some problems at the field. People see what I am using and think it is unsafe after reading all the bad press in these forums. So I asked for clarification. Within 12 hours I received this response: We have stated before that our system uses a predictive hopping scheme. The only time our it hops is when the noise floor is rising/falling in a predicted pattern, long before any type of potential problem occurs. The idea behind this is to increase the range. Less noise = longer range. As stated repeatedly, REAL WORLD tests clearly show that when a single frequency on 2.4HGz is saturated, the entire band is also saturated. It does no good to hop when there is clearly no place to hop. However, to make the masses all warm and fuzzy, we are making a small change to the firmware that allows the system to hop during a fail-safe condition *if* there is actually an available frequency. So, people can perform their bench tests and easily see the change (and feel happy). In reality, the only time we have ever seen a case where this is needed is when a high power 2.4GHz video transmitter is being used directly next to the receiver (and is turned on after our system is turned on). You can also completely lock out a Spektrum system using two video transmitters next to their receiver. It needs to be clear that bench test conditions do NOT replicate the reality we have at our flying fields or in the air. We have traveled the country monitoring the 2.4GHz band, and there are simply no locations where a single frequency is turned on randomly, and with enough power to effect our system. Interference either occurs across the entire band and causes a problem, or does not cause a problem at all. In every case we have seen, ISM devices always co-exist, even on the exact same frequency. It is required under FCC/IC/ETSI rules to co-exist. Non-ISM devices do not have this requirement. Non-ISM devices would be video transmitters and radar. Video transmitters can only affect our system in the direct vicinity. Radar saturates the entire band, so it kills ALL 2.4GHz systems, including those that use true frequency hopping. Our system is the only system that uses bi-directional communications to immediately re-send data that is lost. All other systems require that they wait for the next frame. It is certainly possible to have many frames coincide with bad data and thus you lose complete control during this time. With our system, you don't. That's easy enough to "bench test" as well. We do have to say that our competition is doing a great job of stirring up things. We appreciate the extra attention we are getting. You are welcome to post this information to the flying giants website." And here it is - straight from the horses mouth. Do we fly airplanes or just sit around doing bench tests. For me it's in the flying that proves the system.

More pap from XPS. . .

"Keep the masses all warm and fuzzy". . If JD had any chance of EVER getting my business, he lost it with that little line right there. What a condescending, arrogant, assinine way of referring to the people who are going to be putting money in HIS pocket.

How do you do "real world" testing on something that cannot be proven on a test bench?? You CAN'T put an oscilliscope on a plane and fly it and observe the results, can you? Whose "Real world" results are we talking about" a Cell Phone manufacturer???

Quote: For me it's in the flying that proves the system

It's also the CRASHING that disproves the system. One crash of one of MY planes, because YOUR radio system lost link when you said it would not, is enough to have me at your doorstep demanding your head.




After remarks like this from JD, I can see NO reason to even try to give him the benefit of the doubt any more. As for not being able to get onto the FG site. . . perhaps his fingers have a problem typing out www.flyinggiants.com. Perhaps he should book mark it instead of trying to type it.

Does he think we are stupid??? What an arrogant Ba$&*(#. . .

[Kiwi]

Guys lets not be the judge and executioner at the same time here.

I will try to answer some of the questions you have raised.

The test was only intended to try and make XPS hop. I was not interested if it went into fail safe or retained some semblance of control etc etc.

I raised the noise floor slowly using several different devices. Common wireless router, 2.4GHZ video transmitter, 2.4GHZ transmitting device that allows me to send pulses, continous, and frequency hopping across the entire spectrum. That is I can set the device up to send 10 or 20 second bursts on Ch 1 to Ch13 at will.

My tests never ever swamped the entire 2.4 Ghz band width. The signal generation devices I used left at least 9 channels always open and free from interference. In other words if XPS had wanted to move there was plenty of free airspace available to it. FASST was happily sharing that airspace and the next set of tests will have a spektrum system running along side. That will be six different RC devices all being asked to play fair in a noisy environment with random frequency generation over the top to mix it all up.

I am not at all bashing XPS, its a system and it works. Its a single channel locked frequency RC device that is supposed to be superior to a 72Mhz single channel system. Thats all I have to say about it. Its your choice how you want to interpret what I tried to demonstrate as opposed to what XPS says.

All I ask is if it hops and has some secure way of avoiding interference on a SINGLE FREQUENCY then why does XPS not show us how it works. Surely the man himself could dispell all this negativity by just doing a short demo on the super secret way it is designed to hop.

If he needs a Tx module and an Rx module I am sure we can agree to send the two units I have been loaned to him and then JD can show us with the current units on the market hop and save peoples valuable models from crashing..

As for comparing XPS with SPEKTRUM or FASST thats not even a race.

SPEKTRUM at its worst is at least twice as reslient as XPS because it uses two very well spaced channels. I have tested them on the scanner but have not subjected them to a lot of noise yet. Dont worry its coming up. But two channels is 100% better than one dont you think??

As for FASST I am with XJET: I have run it on the scanner with XPS, video, noise generators etc running all around it. It uses every nook and cranny to find a place to send a signal. It certainly has never even looked like slowing down YET!!!!

As for the bench testing not being relevant and flying is the proof of the pudding!!! Well that the biggest bunch of bullsh!t I have ever heard. All the devices and testing I done were with devices you will find at any big RC event except for the signal generator. That stays hidden at the field and never ever used. However with SPEKTRUM and FASST it would be safe to use as it only ever generates a signal on one single WI-FI frequency.

As XPS state: if someone turns on a WI-FI video transmitter it blows XPS out of the water. Unfortunately the video guys are not following the XPS super secret rules of noise generation so XPS fails. 2.4 GHZ video is only transmitted on a single frequency. One of thirteen available. It does not blanket the ENTIRE 2.4 Ghz band. So if that video camera only uses one channel, why cant XPS find a a way off that channel to one of the other 12 clean ones. THAT IS WHAT BOTHERS ME: It s not as if those videos hog every channel and all the band width. They dont. SPEKTRUM and FASST live with them just fine.

SO WHY DOES XPS NOT HAVE THAT RESILIENCE????

Simple, because it cant change channels once its locked in.

Now if someone turned up at your field with a bank of 2.4 Ghz video cameras then its just possible that SPEKTRUM might get knocked around or knocked out but thats going to take at least two cameras working at the exact same time on the exact same frequencies as SPEKTRUM uses. The chances of that are practically nil (ZERO)

XPS takes a serious hit because it always defaults to channel one if there is no traffic in the area..

And guess what channel nearly all simple 2.4 Ghz video camers use. Channel 1. IN fact they appear to use channels 1 to 4 in all the models I have found so far.

Guys my intention here is to be contructive, not blindly defiant because of some brand loyalty. I own FUTABA, SPEKTRUM and ASSAN. I dont have an orange, red or gray shirt. I wear my FG swag to events. I really dont care about brand. I just want my models flying as safe as humanly possible with the absolute lowest possibilty of being shot down or taken out by a rotten communications link.

What I say here is only my own personal assesment and is nothing at all to do with FG or any other manufacturer. As for tthe competion doing a good job on raising the debate about XPS let me make one thing very clear here. Not one device (RC) has been given or loaned to me by a company manufacturing or marketing RC equipment. Its mine, or loaned to me by other FG members wjho want to see what all the fuss is about. They want to see XPS hop, FASST stand up to some serious noisy environments and see SPEKTRUM do the same.

And finally if XPS cant log on and watch my video that surely bemuses me. Because when they were hyping XPS all over the place for free they had no issues logging in here and posting videos and propaganda.. Maybe I need to send them the password they have obviously forgotten or conveniently lost..

I do not have the devices to totally swamp the entire 2.4 Ghz spectrum and see no real reason to go and procure such a device. As for the comment that the 2.4Ghz band witth is either totally swamped ot totally clean (XPS statement
As stated repeatedly, REAL WORLD tests clearly show that when a
single frequency on 2.4HGz is saturated, the entire band is also
saturated.)

Who ever made that statement still beleives in fairies.

[ricoalonso]

	Quote:
	We have not seen the video. We can't access the flying giants site apparently. ...

I don't know about that but... anyone can register in FG and access the video. In fact, I search 'JimDrew' in FG and I see that he is a registered user.

	Quote:
	We don't fly our planes sitting on a bench.

If that is their reasoning, then pls allow me to bend the logic a little more and ask: When we do our 'range testing' for a new installation, do we range test on the ground or while flying?

	Quote:
	As stated repeatedly, REAL WORLD tests clearly show that when a single frequency on 2.4HGz is saturated, the entire band is also saturated.

Again, that is an assumption which apparently is not always true.

Thanks,
Rico.