Going FASST!

[Ededge2002]

I know the responce time is measured in mili seconds and I was using good equipment previously but I did feel that the planes felt smoother and if the word "lighter" could be used I think its what I would say.  Could this be the faster speed of the signal and higher resolution? 

[pmackenzie]

What system are you coming from?
You can compare latency of various systems here:

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


FASST is not spectacularly fast  , 18msec frame rate I think.
But depending on what you were using before that could be a big improvement. Some of the Furaba PCM stuff was pretty slow.

Airtronics SD10G like Colin and my brother Ivan flies is just about the fastest system out there.
I am hoping that FrSky ups their game with the new Taranis and its new PXX digital protocol, but I fear it will still be slow.

Pat MacKenzie

[Ededge2002]

I was using Futaba 9C with pcm on the Enigma glider(for the failsafe), 
Straight Fm on other planes
Others again with the Spektrum DM-8 module. 

do you know where i could print that chart from?  its tough to look at all the numbers at once hahaha

This post tells a shocking tale!
Quote"
This just in...
Finally got around to testing a Futaba 9C with an R149DP PCM receiver. It's not good...
Minimum Latency to First Change: ~ 44ms
Minimum Latency to Last Change: ~ 110 ms
I found it more difficult to test this setup due to the odd nature of how the channels change so I only went for the minimums. In theory you would add one frame time to get the maximums.
Bottom line... The 9C is sloooowwww. The Futaba PCM1024 scheme is partly to blame of course."

My understanding is that the Fasst numbers are 14ms in low speed mode and 7ms in high speed(requires digital servos mode)

[pmackenzie]

So you are going from what was arguably one of the slowest systems out there (9C running PCM mode) to a much faster one.
No wonder you noticed the difference.

Frame rate is one part of the equation, computational speed is another. It might take 4 or 5 msec to do the calculations.
So you can miss the next frame if your stick input was too soon before the end of the current frame.
This means that average latency would be something like the frame rate plus the calculation time.

It requires some careful work to reduce the system latency. Airtonics did a good job. It seems like Futaba has a poor history.
I think that the published results on runryder sort of pushed everyone to up their game. Before that there really was not any independent testing.

I have a setup to measure this and will see how good the Frysky transmitter is when I get one. As I said their module systems, which I use in my gliders, is pretty slow.

Pat MacKenzie

[Ededge2002]

If you ever wanted to measure the fasst let me know! 

in reading the chart it looks that I went from 80 something ms down to sub 20ms.  that seems to me like a fair jump by the numbers! 

With the digital servos and on high speed mode I swear the servos are already moving when i move the sticks!  I havent flown the one plane I have set up like that though.