rrTV-PHOTO   New HD TV
HOME   rrTV-PHOTO   GALLERIES   MY GALLERY   HELP-FAQ
myHOME PM pmRR MEMBERS 711 ONLINE 46 EVENTS SEARCH REGISTER  START HERE
 
48 pages [ <<    <     39      40     ( 41 )     42      43     NEXT    >> ]74487 viewsPOST REPLY
Revolution Models . CarbonXtreme . Midland Helicopters

.
.
Radio - Servo - Gyro - Gov - Batt > TX/RX eCCPM Latency Test Results
 
 
AirWolfRC
Elite Veteran
Location: 42½ N, 83½ W

If the servo is programable, then it is by definition digital since analog computers are not prevalent in this industry or any other. Since it is programable, I would certainly expect PIDs to be used, but not fancy ones. Accel and decel ramps with dead band is about all.

Resolution would be a matter of the A/D in use.

Analog would not be out of the question and could be done strictly based on pulse widths, converted to digital values in the internal processor.

I hapen to have that schematic from years past. Current schematics are considered proprietery and simply not available.
02-26-2008 02:16 AM
HOMEPAGE  
 
 
Four Stroker
Veteran
Location: Atlanta

The Kraft chip from AirWolfRC rulled supreme for about a decade. Proline used the same chip. Before the chip, Proline had a 12 transistor version which was essentially identical in function. Before that there was a 10 transistor version that did not have the full bridge output and required the battery to be center tapped. The two chip Futaba analog amplifier is probably the same circuit.

The new digital amplifiers in servos are probably just slightly better. The first thing engineers do is to implement the same linear control loop digitally. The 300 Hz pulses to the motor is new ! I'm sure there is still room for improvement.

A PID is of course still a linear control loop. I want to test some of those brushless servos.
02-26-2008 02:22 AM
 
 
AirWolfRC
Elite Veteran
Location: 42½ N, 83½ W

The idea of the 300Hz to the motor is to give full torque even though you don't have full speed or average voltage.
02-26-2008 02:45 AM
HOMEPAGE  
 
 
w.pasman
Elite Veteran
Location: Netherlands

Would it be better to put the discussion about servo motors to another thread, I thought this thread is about *Tx/Rx* latency?
02-26-2008 09:04 AM
HOMEPAGE  
 
 
GimbalFan
Elite Veteran
Location: Copter County, Nv

Quote 
Would it be better to put the discussion about servo motors to another thread
Sure 'nuff, but the problem seems to be that everything happening between the tx sticks and the blade grips will always be endlessly fascinating, even though the subject of this thread ends (technically) at the servo connectors.

op-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-t
02-26-2008 10:24 AM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

I asked Mark if he could split the thread back when it turned into a servo discussion. No can do, unfortunately.

> Resolution would be a matter of the A/D in use.

Why does it have to be A/D? Why not pulse width comparison? Then it is timer resolution.

- John

Protos -- Logo 14 -- Logo 10
02-26-2008 01:11 PM
 
 
Four Stroker
Veteran
Location: Atlanta

I think AirWolfRC is talking about A/D from the voltage reference pot. The servo input (digital servo) should just be a timer interrupt.
02-26-2008 01:23 PM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

I know he is talking about the pot. But one can also generate a pulse width from the pot position just like good ol' analog servos. Just a thought and would seem much more simplistic than a 13- or higher bit A/D in a noisy servo environment. I know that the control loop parameters of the JR digital servos can be tweaked via resistor changes.

- John

Protos -- Logo 14 -- Logo 10
02-26-2008 01:27 PM
 
 
AirWolfRC
Elite Veteran
Location: 42½ N, 83½ W

Hmmm . . . 5MHz clock and counting while the pulse is present could give about "5,900 steps" resolution. 0.91ms to 2.09ms
02-26-2008 04:50 PM
HOMEPAGE  
 
 
Four Stroker
Veteran
Location: Atlanta

Yeah, It could be a hybrid chip.
02-26-2008 08:17 PM
 
 
747
Heliman
Location: Toronto, Canada

8103 with spektrum module

Hi JKos

I was just pointed out to this thread by a friend of mine, excellent work.
I have a Jr8103 radio, and I am looking to get the best of the 2.4 speed wise.
My choices are
8103 with spektrum 2.4 module
X9303
DX7
I have seen your test results for x9303 and DX7 and 8103 with PCM and FM, but not seen of a 8103 with a spektrum module.
From your results, it seems like the DX7 is even faster than the X9303. Since the 8103 and 9303 results are almost same with FM, can I expect that the 8103 with spektrum module will be the same as 9303 with a spektrum module?
What's my best option out of the 3 above?
Thanks in advance
03-05-2008 12:23 AM
HOMEPAGE  
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

> Since the 8103 and 9303 results are almost same with FM, can I
> expect that the 8103 with spektrum module will be the same as 9303
> with a spektrum module?

Exactly correct.

- John

Protos -- Logo 14 -- Logo 10
03-05-2008 07:05 PM
 
 
747
Heliman
Location: Toronto, Canada

Thanks
03-08-2008 04:01 AM
HOMEPAGE  
 
 
happyfly
Senior Heliman
Location: HK

Hi John, is there any performance difference between 12FG FASST and 14MZ FASST with same RX R6014FS? Is G3 2048 on 14MZ only applied on PCM but not FASST? Thanks for advice.

Cheers, Happyfly
03-08-2008 06:36 AM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

12X numbers posted. Not on the graphs yet as I'm away from home and don't have the spreadsheet with me.

The minimum latency is fractions of a millisecond close to 12Z/TM-14/R6014FS system. But the 12X is better overall for two reasons. It is a fully synchronized system which means the actual stick sample to receiver output time is constant as opposed to the 12Z/TM-14 system which has a varying stick sample to receiver output time. And, it updates all 12 channels every frame as opposed to the only 2 out of every 3 frames like the 12Z/TM-14.

- John

Protos -- Logo 14 -- Logo 10
03-21-2008 07:17 PM
 
 
rroback
Key Veteran
Location: Irvine (UCI), Ca

Seems fairly decent, and even more important, when I compare my 14mz/tm14, and the 12x, I'm impressed by the 14mz, since it is still a module based system, versus the 12x, and yet their numbers are fairly close. The tm14 just need to have the max latency reduced, not sure how that's possible...

Rhett... There's no power like E Power!
03-21-2008 07:25 PM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

> I'm impressed by the 14mz, since it is still a module based
> system, versus the 12x

The 14MZ with a TM-14 module is every bit as integrated as a 12X. Just because a physical module is plugged in doesn't mean it isn't integrated in terms of communication between the tx and module. The 12X will also be available as module based and integrated versions. There will be zero difference in latency between the module and intergrated version when using the 2.4 GHz module.

> The tm14 just need to have the max latency reduced, not sure how
> that's possible...

Based on how Futaba choose to implement FASST, it's not. They would have to revamp FASST. With the TM-14 and in multi mode, channels are only updated 2 out of every 3 frames. Every channel is updated each frame on the 12X.

- John

Protos -- Logo 14 -- Logo 10
03-21-2008 08:29 PM
 
 
rroback
Key Veteran
Location: Irvine (UCI), Ca

Any idea why they would choose the 2/3 update rate, versus 3/3?

Rhett... There's no power like E Power!
03-21-2008 08:57 PM
 
 
RCHelicopterGuy
Veteran
Location: Michigan

I gotta say, I'm surprised at the 12X's numbers (and not in a good way).

By the numbers, JR still can't make a radio with a link as fast as a 15-year old, non-current Airtronics product.

Let's not turn this into a "speed isn't everything" debate, or conjecture on what the brain can or can't perceive. I'm simply saying that I'm surprised that the continual evolution of radio products hasn't yet wrought a truly fast JR radio. You'd think that with all the current advancements that we have now compared to 15 years ago, someone would have played catchup.
03-21-2008 09:11 PM
 
 
Ace Dude
Elite Veteran
Location: USA

Anyone know what the maximum length of a frame is? Perhaps this is one of the limiting factors.



03-21-2008 09:11 PM
 
 
48 pages [ <<    <     39      40     ( 41 )     42      43     NEXT    >> ]74487 viewsPOST REPLY
HeliProz . ZoomsHobbies . HeliHobby

.
.
Radio - Servo - Gyro - Gov - Batt > TX/RX eCCPM Latency Test Results
  UPDATE SCREEN   PRINT TOPIC Advertisers 

Subscribe to This Topic

Saturday, August 30 - 2:58 am - Copyright © 2000 - 2008 runryder.com | email | link to rr | runryder needs cookie