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Radio - Servo - Gyro - Gov - Batt > TX/RX eCCPM Latency Test Results
 
 
w.pasman
Elite Veteran
Location: Netherlands

Pepe,

The minimum latency is not that relevant, it's the maximum latency and the latency spread that really counts.
06-19-2008 07:57 AM
HOMEPAGE  
 
 
Four Stroker
Veteran
Location: Atlanta

I also suspect that the distribution (shape of spread) is ergonomically or phychologically important. I can't see how your brain compensates for a uniform (flat) distribution.
06-19-2008 01:43 PM
 
 
JKos
Elite Veteran
Location: City of California in the state of Maryland

FS,
Actually, the flat distribution is good because it means there is a consistent latency between reading the stick position and the result making it out of the receiver. The FASST distribution actually shows that the latency is inconsistent.

- John

MSH Protos
06-19-2008 01:48 PM
 
 
wileyeco
Heliman
Location: owosso mich usa

john, have you tested

the rds 8000 system yet?
06-19-2008 02:12 PM
 
 
sharam
Elite Veteran
Location: Northern California

Jkos, just a quick note to thank you for the immense amount of great information that you have posted in this thread! It certainly has enhanced my understanding of these systems.

Verba volant, scripta manet
06-19-2008 05:09 PM
 
 
GimbalFan
Elite Veteran
Location: Copter County, Nv

^^^ Indeed.

op-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-t
06-19-2008 05:54 PM
 
 
JKos
Elite Veteran
Location: City of California in the state of Maryland

Thanks guys.

RDS8000 numbers added. It's right up there with the DX7. A few tidbits on the RDS8000...
1) It uses PPM between the tx front end and the 2.4 GHz section (a Stylus module should be a no-brainer),
2) You can only set failsafe on channels 1-4 and channels 5-8 cease outputting pulses (servos will go limp),
3) If failsafe is not set, all channels cease outputting pulses,
4) No EPA adjustments in CCPM mode,
5) Receiver output is classic PPM style sequential pulses, and
6) Synchronous system (one-to-one match between stick samples and receiver output frames).

- John

MSH Protos
06-20-2008 04:43 AM
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

Quote 
4) No EPA adjustments in CCPM mode,
This one raises an eye brow.
06-20-2008 03:13 PM
HOMEPAGE  
 
 
JKos
Elite Veteran
Location: City of California in the state of Maryland

> This one raises an eye brow.

It's the same as on the RD8000. The aileron, elevator, and pitch channels' EPAs become the Swash Mix/Swash AFR values. There is also no way to reverse the ail, ele, and pitch functions as you do by changing the sign of a Swash Mix/Swash AFR value. You just play around with swash type and which channel you plug the side servos into.

I think the failsafe is much more of an eye brow raiser.

- John

MSH Protos
06-20-2008 03:23 PM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Quote 
I think the failsafe is much more of an eye brow raiser.

Yeah, no kidden! Is the pitch channel the typical ch6 output? So, if you go failsafe, your collective goes who-knows-where on a mechanical mix setup, or the pitch servo on a CCPM machine limp?

Break out the video cameras.
06-20-2008 03:59 PM
 
 
JKos
Elite Veteran
Location: City of California in the state of Maryland

> Is the pitch channel the typical ch6 output?

Yes. ATX's defense to the safety implications of this design is that going into failsafe is extremely unlikely. Wrong answer! It is an unacceptable, bad design, period.

- John

MSH Protos
06-20-2008 04:06 PM
 
 
TMoore
rrProfessor
Location: Cookeville, TN

Quote 
RDS8000 numbers added. It's right up there with the DX7. A few tidbits on the RDS8000...
1) It uses PPM between the tx front end and the 2.4 GHz section (a Stylus module should be a no-brainer),
2) You can only set failsafe on channels 1-4 and channels 5-8 cease outputting pulses (servos will go limp),
3) If failsafe is not set, all channels cease outputting pulses,
4) No EPA adjustments in CCPM mode,
5) Receiver output is classic PPM style sequential pulses, and
6) Synchronous system (one-to-one match between stick samples and receiver output frames).

That's your opinion John. I don't happen to agree with it. I've been flying the radio for a while now and don't see an issue with the way that Sanwa did the failsafe. The radio works. I just set up the CCPM system and had to use one mix to make the swashplate go straight up and down. I don't see that as an issue either. When Alan Szabo was using the radio to fly the Kalt Mercury, he must not have seen it as an issue either. Why don't you ask him.

TM

Buying tools is half of the equation, knowing how to use them is the other. - T Moore
06-20-2008 05:41 PM
HOMEPAGE  
 
 
w.pasman
Elite Veteran
Location: Netherlands

If the throttle servo is on ch6 (would that be a possible config?) and the servo does not receive any more pulses, the servo probably goes limp as you say. In that case a spring on the throttle can pull it close...
06-20-2008 07:36 PM
HOMEPAGE  
 
 
JKos
Elite Veteran
Location: City of California in the state of Maryland

TM,
> That's your opinion John.

What you quoted is not opinion, simple facts of the system. Perhaps you meant to quote my assessment of the failsafe solution.

Failsafe is not about how the system operates under normal conditions; it's all about the time something goes wrong. That's when you'll find out what the failsafe solution really means.

Are you willing to turn off your tx and find out what happens? If you feel so strongly that the system is safe, go for it and please let us know how it turns out.

With regards to CCPM setup, again, simple fact of how the radio works. It is what it is and I did not say it was good or bad. Notice I said, "A few tidbits..." and then listed facts.

- John

MSH Protos
06-20-2008 07:48 PM
 
 
Four Stroker
Veteran
Location: Atlanta

If you want a 2.4 GHz radio with full independent channel fail-safe (ubiquitous in the the 72 MHz PCM days), then Futaba is the only game in town.
06-20-2008 08:00 PM
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

The realty of it is that signal loss is a very short term thing. Less than a second most times. And normal non-failsafe operation has often less consequences than fail-safe as recovery is faster (Spektrum not included). And if it is a long term thing, you're going in anyway.
06-20-2008 08:13 PM
HOMEPAGE  
 
 
Harris
Senior Heliman
Location: Cyprus

The whole thing about failsafe is to save YOU and the spectators, NOT the aircraft! If the throttle doesn't go to a predefined position when control is lost then the system is dangerous! Period!

By the way, XPS also offers independent failsafe settings for each and every channel. The programming, though, is done on the Rx (or via a pc) and not from the Tx. Not as elegant as Futaba's but it is probably the only solution for a module based system.
06-20-2008 08:18 PM
HOMEPAGE  
 
 
Four Stroker
Veteran
Location: Atlanta

Programming the XPS in multi-color Morse code is definitely not elegant. On the other hand, it has the full -40C to 85C industrial temp. range.
06-20-2008 08:23 PM
 
 
JKos
Elite Veteran
Location: City of California in the state of Maryland

> If the throttle doesn't go to a predefined position when control is
> lost then the system is dangerous!

The throttle channel (ch 3) is covered by the failsafe, if set.

BTW folks, don't get me wrong, I think ATX makes good, solid products. I still think the Stylus is an amazing radio. But I just don't understand how anyone could have let that failsafe implementation out the door. It just doesn't make any sense and I will continue to say it is flawed until it is fixed.

- John

MSH Protos
06-20-2008 08:27 PM
 
 
seattle_helo
Key Veteran
Location: Seattle, WA USA

Quote 
ATX's defense to the safety implications of this design is that going into failsafe is extremely unlikely. Wrong answer! It is an unacceptable, bad design, period.

It really is the wrong answer. Amazing that the system is sold as is with that configuration. Why tolerate it? The low cost of ATX gear? A huge gamble, IMO.

nick
06-20-2008 10:16 PM
HOMEPAGE  
 
 
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Radio - Servo - Gyro - Gov - Batt > TX/RX eCCPM Latency Test Results
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