JoeyCoates

Wow, I have not looked at this section on RCU in a few weeks, and now I click on it and this XtremeLink stuff has blown up!

Anyway, my question is: does the XtremeLink 2.4 system help to improve a radio systems latency? I read the thread where many of todays systems were tested for latency, and the 9c (which is what I fly) was a good bit slower then the 12z, 14mz, DX7, Stylus, ect. Everyone talks about how "connected" these radio's feel due to there low latency #'s so I was wondering if switching to the 2.4 system improves the speed, or are the low latency #'s a product of how the radio was designed in the first place? I could understand going to something like the XTL if I gained speed as I like my 9c, but if it does not help then I would just as soon wait for the 12FG that is designed from the start as a 2.4 system. Thanks.

d_wheel

Blew up? Where can I find this information?

I think this indicates that latency is more of a buzz word than anything else. A state of mind. Very subjective. The latency [link=http://www.runryder.com/helicopter/t172571p4/?highlight=latency]NUMBERS[/link] for the 9C/XPS look bad, but the field reports are saying "locked in feeling", or "no difference in feeling at all". No one is saying, "The added latency really makes this thing feel sluggish.".

Later;

D.W.

GalenB

My Feedback: (18)

The 12 FGA is not a purpose built 2.4 Ghz radio -- It uses the same module as the 12z/14MZ. There are unfortunately some misleading pictures that have been posted and printed in various RC mags...

http://2.4gigahertz.com/ now shows the correct picture for this Tx...

Silent-AV8R

And as far as being "purpose built" I do not get the fixation on that. Futaba has already said that their module based SS FASST system will perform the same as if it were "built" into the TX. Other module based systems may not perform the same, but Futaba likely knows something about the workings of their transmitters that others do not. This is evidenced by the fact that the Futaba FASST module for the 12Z and 14MZ do NOT use a cable into the trainer port like XPS and Spektrum will have to do.

GalenB

My Feedback: (18)

I was only correcting a misperception about the 12FGA... As for me -- I have no doubt the Futaba modules will perform well in my 8U Super and my 9z WCII. The only question I have for myself is: "Should I get a 12z?" I love my 9z, but the 12z with its upgradebale firmware and CF storage is compelling...

DKflyer

My Feedback: (2)

What would you expect them to say??? An add-on module would almost have to add some latency, but we'll see when it comes out.

The Xtreme Link system will add about 20ms of latency to the PPM stream of whatever system it is added to. The 9C is at the slower end, and the XL system will make it about 20ms slower. However, the 9C is faster in PPM mode than in PCM, so in reality the latency will be about the same as it is now when using PCM.




I can feel a difference for sure, but I am flying helis so maybe that makes a difference. Fly the 9C back to back with a 14MZ, Stylus, or DX7, and you can definitely feel a difference.

DK

d_wheel

[quote]ORIGINAL: DKflyer

I fly a 14mz, dx7, and 9c in my aircraft, plus anything else the people I help out hand me. I can't really say that I can "feel" any difference in any of them.

If I were buying a new system and everything else was the same I MIGHT consider latency in order to make a final decision. It is absolutely the lowest item on my list of priorities.

Later;

D.W.

tkilwein

I can tell the difference between my 9Z and 14Z back to back.
I do not regret buying it.

Waiting for the modules to start selling on the 14Z, will try one and see how it does.

JoeyCoates

I am with DK, I fly heli's along with airplanes and on a heli there is a difference. I would not notice it on an airplane, but you DO notice it on the helicopter. When my Raptor was stock I flew mine and then a new guy came out so I helped him set his up. They were the same down to the servo's with the only difference being that he had a DX-7 and I have/had a 9chp. There was a difference, I do not know how to explain it, but everything was just sharper when flying his Raptor. The only substantial difference that I can find between the 9chp and the DX-7 as far as simple flying goes is that the DX-7 has a lot better latency number. I know that the bells and whistles are different, but when just twidling the sticks that was the biggest difference I could find so I guess that it does mean something.

And there is no way that I would add the XTL to my 9chp, if it does not speed things up to DX-7, 12z, 14mz, Stylus speed then I will just buy another radio system. Either the new 9303 or the 12FG. Heck maybe even the Spektrum version of the 9303 when it comes out as they are the same thing.

Gulliver

Please correct me if I am wrong - and Iknow you will - but as I understand "latency" it is the delay between the signal intended for channel 1 and the higher channels. If this is the case It would seem to me that this is inherent in the transmitter and that the RF module, which just encodes the transmitter output, won't make any differnce.

JimDrew

My Feedback: (16)

The 9C in heli mode (120 degree CCPM) is actually about 4 frames behind! It is the WORST radio you could ever use for a helicopter application. Jason Krause showed me this one day. You can actually move the collective up and down, and visually see the lag. No other transmitter in history has this kind of a problem with CCPM.

d_wheel

Yes, I have noticed that also. That was the only difference I could "feel" when I replaced my 9c with a 14mz on my ION heli. I was under the impression that this was not in the "latency" category, but instead because of channel groupings. If this is considered latency, then I will have to modify my definition slightly.

Later;

D.W.

d_wheel

Latency is the time between when the stick is moved and the corresponding servo moves.

Later;

D.W.

rmh

yeh-- now ---you can also use it to describe what happens when two or more outputs are accessed by the same stick input.
for example: elevator on an aircraft -having two channels being used --say ch2 and channel 10
moving th stick rapidly -can and may and in most cases does -show a lag in speed on one channel - on th DX7--and on the $$$Futaba 14 the difference in noted speed to a position is pretty darn close . On the Futaba 9C (or the JR 10X -if you group 2 and 10 on the 10x )-the delay is as obvious as bananna in a coal pile. run em slowlyand it looks OK but at speed - it's a problem.