Xtreme Power Systems

[kgfly]

rstacy - You are right, initial *independent* testing of the XPS has shown a latency contribution (from input to the Tx module through to output at the Rx servo plugs) in the range 22ms to 44ms, considerably more than the 2.5ms claimed.

Note that the tests are independent, done by JohnK across a wide range of Tx/Rx combinations, primarily to compare eCCPM performance but now extended more broadly. So the chart was not created by XPS at all.

XPS have said they have made firmware changes to reduce the variation and JohnK will retest when he receives the update.

On the other hand, most users report the same or better feel with the Tx using the XPS module. It is certainly unclear at this stage what's real and what's a form of placebo affect - they expect it to feel better so it does, even if it isn't!

It is early days and I think we will see the performance improve.

[DavidH]

It is certainly unclear at this stage what's real and what's a form of placebo affect - they expect it to feel better so it does, even if it isn't!


The above statement says it all. This latency stuff is placebo. We are talking milliseconds here that over 90% of the humans can not tell a difference unless someone tells them it is different.

David

[spork]

The above statement says it all. This latency stuff is placebo. We are talking milliseconds here that over 90% of the humans can not tell a difference unless someone tells them it is different.

David

That's what I thought as well. But I wrote this little program to test that theory. At 100 msec of latency it becomes difficult to write your name.

http://www.helifreak.com/download.php?id=19778

[capebob]

Eleven days and counting. Still no XPS system.

[DavidH]

Bob,
Have you been charged on your credit card for this order ?

David

[flymo]

Still no delivery here. Starting to think I should have just waited for futaba modules.

[capebob]

David,
PayPal. They got the money. I'm not all that upset about the wait, I'm only upset by the lack of communication. It seems to me that if they are having some sort of problem getting these units out of production and into shipping containers a little explanation would help a lot. There are rumors around that there have been production problems. I can understand that, but the silence that surrounds XPS at this point is disconcerting.

Bob

[DavidH]

I would be filing a complaint with Paypal. Then maybe you will get a response. Longer you wait with paypal, harder it will be to make a claim I would think.

On one of the other forums, I saw mention of something about the wrong antennas being on the receivers or modules. Not saying that is the case, just what I have read elsewhere.

David

[Motions]

I was assured that orders that were placed have "unfortunately" been shipped. They say unfortunately because they apparently shipped out with the wrong antennas and are telling people to send them back for a "free upgrade" when you receive them.

This was straight from XPS.

[capebob]

Scott,

Just where on their web site did you find this information or did they respond to an email from you? Also, if they were shipped USPS Priority Mail just what massive black hole did they fall into?

Bob

[DavidH]

Bob,
Interesting discussion going on RC Groups. Maybe you can contact Jim thru there.
LOL
http://www.rcgroups.com/forums/showthread.php?t=656877&page=235

That is a 240 page thread. The link is just todays post.
USPS Priority Mail would have been to you 3 days after order was shipped from Arizona.

http://www.xtremepowersystems.net/

Due to the overwhelming response of the XtremeLink sales, we have been forced to limit availability so we do not get so far behind in shipping. We are adding to our online shopping cart inventory every day

Amusing the above statement is right below this
Click HERE for important information!
http://www.xtremepowersystems.net/jr.php

I guess they want people to modify there module boards. LOL

David

[Motions]

Bob, I received this info through email. I highly doubt they would post that on the website...yet anyway. I don't have the details on what is exactly wrong with the antennas.

[capebob]

I've been following the discussion on rcgroups. Most of those guys are certifiable. :D

[Pinecone]

You do not HAVE to return the module for a new antenna. But if you want to, they will upgrade the module for free.

They found one field in Vegas that has a 2.4 GHz video link (dish to dish) that causes one spot that there is trouble with the system. But that filed is also known for problems with other 2.4GHz systems as well as 72 MHz systems.

So they are offering an upgrade to a 2.1 dBi gain antenna from the 1.8 dBi gain one supplied.

Also they are doing this after one crash at that site and a couple of days of testing. Unlike some other manufacturers who do't seem to want to ever admit that their systems may not have problems or offer updates to solve identified problems. :)

[kgfly]

It is certainly unclear at this stage what's real and what's a form of placebo affect - they expect it to feel better so it does, even if it isn't!


The above statement says it all. This latency stuff is placebo. We are talking milliseconds here that over 90% of the humans can not tell a difference unless someone tells them it is different.

David
I think there are shades of grey here. Ask any 14mz/G3 owner whether they can feel a difference and they will assure you they can. Is that due to the 2048 resolution, the low latency, the fancy features or placebo ? Some of each I would guess.

Certainly a difference of a few milliseconds seems unlikely to be noticable and wishful thinking/placebo probably plays a big role. A difference of hundreds of milliseconds, is definitely detectable by almost anyone. A difference of tens of milliseconds, well I think a lot of variables will come into it, but there are many, many reports that suggest that it can be experienced. Perhaps the most credible are from expert pilots and for most it wouldn't matter, but then most folk never drive their Ferrari over 150km/h but most want one anyway :lol:

Another factor that is likely to matter is latency variation. Adapting to a fixed latency is fairly easy, but constantly varying latency where the variation is large compared to the average is probably more noticable than a fixed difference of the same magnitude. Hence one of the concerns with the 7c/9c/9z/14mz1024/T6EX which all have over 50ms/50% variation, far greater than any other system tested and IMO likely to be the detectable region, particularly when flown back-to-back with an alternate system having far lower variation.

Most of us won't get the chance to do a back-to-back comparison before making a purchasing decision so it's back to reading reports from others spanning from bench tests through to flight reports. All part of the fun :D

[SteveL]

I am quite sure the difference in servo speed is far greater than the latency of the radios.

[spork]

I am quite sure the difference in servo speed is far greater than the latency of the radios.

I'm not so sure of that. Lots of servos these days are in the range of 30 deg in 100 msec. I'd be amazed to find one of my servos get 30 degrees ahead of another when I commanded full throw out of both at the same time.

[Pinecone]

Although I have seen several posts of people switching to XPS that find that they perceive a lower latency and that the servos seem faster. Including one where several pilots wer amazed to find out what servos were in a test plane, due to the response.

But PCM does have higher latency, so the PPM+XPS may still be lower.

[Danal Estes]

Measured latency for XPS as sold at Toldeo:

http://runryder.com/helicopter/t172571p1/

[capebob]

Twelve days and still no XPS system. :arggg:

[capebob]

I sent an email to XPS inquiring as to the whereabouts of my order. I received a prompt reply quoted below.

We held a large portion of the orders (starting well below your order
number) to make a change to the antenna system on the transmitter
module. We are resuming shipping and expect to have all orders placed
within the last 10 days shipped out by tomorrow.

I am well satisfied with this response and will report on my experiences with this system.

Bob

[ClayK]

Measured latency for XPS as sold at Toldeo:

http://runryder.com/helicopter/t172571p1/

It would appear that the claims of 2ms of latency are disputable. :shock:

[Probedude]

Hey, they're using Xbee/Zigbee modules!
I've used those in my last oem contract job. Nice modules.
Looks like they're using the higher RF output Pro modules.

Dave

[ClayK]

It is certainly unclear at this stage what's real and what's a form of placebo affect - they expect it to feel better so it does, even if it isn't!


The above statement says it all. This latency stuff is placebo. We are talking milliseconds here that over 90% of the humans can not tell a difference unless someone tells them it is different.

David
I think there are shades of grey here. Ask any 14mz/G3 owner whether they can feel a difference and they will assure you they can. Is that due to the 2048 resolution, the low latency, the fancy features or placebo ? Some of each I would guess.

Certainly a difference of a few milliseconds seems unlikely to be noticable and wishful thinking/placebo probably plays a big role. A difference of hundreds of milliseconds, is definitely detectable by almost anyone. A difference of tens of milliseconds, well I think a lot of variables will come into it, but there are many, many reports that suggest that it can be experienced. Perhaps the most credible are from expert pilots and for most it wouldn't matter, but then most folk never drive their Ferrari over 150km/h but most want one anyway :lol:

Another factor that is likely to matter is latency variation. Adapting to a fixed latency is fairly easy, but constantly varying latency where the variation is large compared to the average is probably more noticable than a fixed difference of the same magnitude. Hence one of the concerns with the 7c/9c/9z/14mz1024/T6EX which all have over 50ms/50% variation, far greater than any other system tested and IMO likely to be the detectable region, particularly when flown back-to-back with an alternate system having far lower variation.

Most of us won't get the chance to do a back-to-back comparison before making a purchasing decision so it's back to reading reports from others spanning from bench tests through to flight reports. All part of the fun :D

Well, I'm no hot pilot, but I've flown my 14MZ/G3 combination and then flown someone else's 9C/149 combination. According to John's chart, the average delta in latency is about 60ms. When I fly the two systems, I can feel the difference even though both systems have similar setups. It's noticeable to me. The 9c feels a tad sluggish. Now, having never flown a 9c prior to flying my 14mz (the 14 was my first radio) I never "grew up" in terms of latency. For me, the 14 was my baseline. Flying something else feels different, I don't feel as connected. If the average latency for an XPS system is ~30ms more than what the original RF system was, I think you may feel a difference. Will it be enough to affect your flying? I can't answer that. I do know that when I fly a system other than a G3 system, I don't feel as connected and that puts butterflies in my stomach.

What is important is the "all important chart" that claimed only adding 2ms to the signal which seems to not be the case. The chart is absent additional information from other manufacturers and it also fails to address that all RF is LOS. The range "may" be greater than another system, but it's still line of sight. Objects in the way may impede or degrade, not necessarily stop a signal.

I hope to try the system when I go to Stator Gator's at some point. However, irrespective of the quality/performance of the system, there are still some questions and concerns that loom in my mind regarding this system. I would love to list them all, but they have been mentioned before on other boards as well as here and it would be beating a dead horse. I hope they are easily explained away, but so far, they have not been. This is all in my opinion of course.

[Pla]

Many orders received shipping emails with tracking numbers on Thursday (5/3). So I guess they should be received Sat-Mon.
It seems XPS delayed shipments until they updated the antenna on the Tx module.