[NSRCA-discussion] Futaba and pattern ( A plus for Futaba)

Mon Dec 24 16:43:35 AKST 2007

Probably a lot of good stuff for the K-Factor.

Merry Christmas to all and to all...

Jim O

On Dec 24, 2007, at 5:30 PM, Derek Koopowitz wrote:

> Once you figure out everything, Jim... can you write a manual for  
> us?  :-)
>
> From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org 
> ] On Behalf Of James Oddino
> Sent: Monday, December 24, 2007 4:30 PM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] Futaba and pattern ( A plus for  
> Futaba)
>
> Earl,
>
> I set the maximum Hysteresis (32) and it looks like the it is about  
> 8 microseconds so you'd have two neutrals about 8 microseconds  
> apart.  In fact the pulse width tends to jump in 8 microsecond steps  
> as you move the sticks slowly.  Not desirable.
> Some of my original lack of a consistent neutral was probably due to  
> the default hysteresis set to 1.  So the sticks are better than I  
> thought.
> I also noted that when switching rates I was getting a shift in  
> neutral until I put the "stick deadband" (with zero hysteresis) in  
> all rates.
> I think I'm going to love this radio.
>
> Jim O
>
>
> On Dec 23, 2007, at 12:24 PM, Earl Haury wrote:
>
>> Jim O
>>
>> On the 14MZ, go to system, H/W, Stick Settings and you are able to  
>> globally set the Response & Hysteresis for each stick. You might  
>> find this easier than using the spline for setting a deadband. (Be  
>> interested in the actual pw / bits difference with each setting if  
>> you measure it.)
>>
>> Earl
>>
>>
>>
>> ----- Original Message -----
>> From: James Oddino
>> To: NSRCA Mailing List
>> Sent: Sunday, December 23, 2007 12:08 PM
>> Subject: Re: [NSRCA-discussion] Futaba and pattern ( A plus for  
>> Futaba)
>>
>> Bob,
>>
>> I would think that 256 resolution would mask poor stick centering.   
>> Think about 3 step resolution. Right, neutral left.  When you  
>> select neutral it is always the same unless you move the stick to  
>> the extreme where you get right or left.  The problem is you can't  
>> trim neutral unless you do it with another channel like folks did  
>> back in the reed days.  Move the servo with another servo.
>>
>> You had many factors affecting trim in your 8 bit system starting  
>> with drift in the servos and an AM link that introduced large  
>> changes in pulse width to the servos as signal strength changed.   
>> You could adjust linkages everyday and not keep up with everything  
>> that was fighting you.
>>
>> So if low resolution masks poor stick centering then more  
>> resolution must emphasize it.  This has always bothered me.  I  
>> learned long ago that the servos can resolve pulse widths that  
>> would appear to be in the servo deadband.  In the early dual rate  
>> schemes we had to adjust the neutral if we changed the dual rate  
>> setting.  I tried using a servo to do this.  Adjust the pot until  
>> the servo didn't move as I switched the dual rate    switch back  
>> and forth. Go fly.  Every time I threw the rate switch the trim  
>> would change.  Went home looked at it on a scope and sure enough  
>> the pulse width was changing.  Adjusted it so it didn't and the  
>> trim didn't change with the position of the rate switch when I flew.
>>
>> This week I got a Futaba 14MZ.  I checked the stick centering with  
>> a scope.  Not perfect.  Plus or minus a few bits.  Now a bit in a  
>> 2048 is only about a half of a microsecond change in pulse width to  
>> the servo so most folks don't care.  However I found that with the  
>> line or spline curve programming of the control sicks I can put in  
>> a plus and minus .5% deadband in the stick.  Now the centering is  
>> perfect no matter how I return the stick to neutral and I can trim  
>> it in .5 microsecond increments.
>>
>> I love this high tech stuff.
>>
>> Jim O
>>
>>
>> On Dec 23, 2007, at 5:37 AM, Bob Richards wrote:
>>
>>> Jim,
>>>
>>> You may be correct, the stick centering depends on the quality of  
>>> the stick. But, throw in 256 instead of 1024 resolution, the step  
>>> size is now 4 times as much and it would be much more noticeable.
>>>
>>> Ok, if we were flying the 4 channel Conquest transmitter (cheap  
>>> plastic gimbals) with 148 servos (non-ball bearing) in a slow  
>>> moving trainer, we probably could not tell the difference between  
>>> 256 and 2048 resolution. So, would I be better to fly a Conquest  
>>> radio in pattern? That seems to be the type logic I would get from  
>>> people that say 256 is "better than most servos".
>>>
>>> Oops, I forgot the Conquest is an analog radio. No steps  
>>> whatsoever. ;-)
>>>
>>> Bob R.
>>>
>>>
>>> J N Hiller <jnhiller at earthlink.net> wrote:
>>> Guys I don’t believe the mechanical stick centering is absolute  
>>> enough especially on a somewhat used radio at least on less than  
>>> top of the line transmitters. The detent design and pivot bearings  
>>> are less than shall we say industrial quality. Bob, I had the roll- 
>>> centering problem you described with my super 7 and felt it was  
>>> due to stick centering not being equal from either left or right.  
>>> I think my 9-C is better but not absolute. I wish I had one of  
>>> those little devices that displayed the signal count to verify my  
>>> suspicion.
>>> Jim Hiller
>>> -----Original Message-----
>>> From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org 
>>> ]On Behalf Of Bob Richards
>>> Sent: Saturday, December 22, 2007 3:37 PM
>>> To: NSRCA Mailing List
>>> Subject: Re: [NSRCA-discussion] Futaba and pattern
>>> Ron,
>>> All I can say is, I flew the Micropro with every intention of  
>>> competing at the '93 NATS with it. I had trimming issues with my  
>>> plane that I could not tune out. Some flights would be good, some  
>>> I could not trim the plane for level flight (slight roll left or  
>>> right). And, yes, I had taken out all the throw I could  
>>> mechanically so I had 100% throws programmed into the radio.  
>>> Frustrated, I decided to put my 7UAP in the plane, and it  
>>> immediately felt good. That is when I decided to do a little  
>>> digging and discovered the resolution issue.
>>> Whenever I mention that 256 is not good enough, I hear all sorts  
>>> of reasons why 256 should be sufficient. Yes, once the stick is  
>>> moved away from center, 256 probably is good enough. But when the  
>>> stick is at center, the darn servo better go back to the same  
>>> position every time. And you need fine resolution at center so the  
>>> neutral position can be varied in small enough amouts to arrive at  
>>> precisely the desired position.
>>> With a slightly worn stick or pot, the neutral position might be  
>>> bouncing between two adjacent steps. With 256 resolution, this can  
>>> be VERY noticeable. With 1024 or higher resolution, not nearly as  
>>> noticeable, if at all.
>>> Given the outcome of the '93 season with my old 7UAP, I'm glad I  
>>> switched out the radios.
>>> Bob R.
>>>
>>>
>>> Ron Van Putte <vanputte at cox.net> wrote:
>>> Hmmmm, I never thought of blaming my radio's resolution for my bad  
>>> flying.  Let's see now..........
>>> Ron Van Putte
>>>
>>>
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>>
>>
>>
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