[NSRCA-discussion] SD-10

[James Oddino]

Our 72 MHz PPM systems do not have infinite resolution because they  
are limited to a 10 KHz bandwidth.  Only so much information can be  
pumped through a given bandwidth.  You can have more resolution at a  
lower frame rate or a higher frame rate at lower resolution.

PPM probably does better in a 2.4 GHz system that has greater  
bandwidth depending on how the signal is processed.  I assume the PPM  
is converted to digital before it is transmitted and is not degraded  
by the RF link.

I have never gone back to 1024 after flying 2048 but I've been told  
you can tell the difference if you go back.

Jim O


On Aug 24, 2009, at 4:58 PM, Jay Marshall wrote:

> A liner, non-digital system such as PPM, has infinite resolution and
> therefore the ultimate "smoothness". I agree, however, that you  
> probably
> can't "feel" a 1/2048 digital step. I suspect that the major  
> improvements
> have been in less latency.
>
> Jay Marshall
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of  
> Atwood, Mark
> Sent: Monday, August 24, 2009 4:19 PM
> To: 'nsrca-discussion at lists.nsrca.org'
> Subject: Re: [NSRCA-discussion] SD-10
>
> I'll take a stab, and I'm blind copying Mike Greensheilds (don't feel
> comfortable putting his email out on the list) who is the product  
> manager
> for ATX here in the states.  He may chime in with additional  
> background.
>
> My understanding is that when Sanwa was evaluating speed vs  
> resolution,
> speed was deemed a much more critical factor.  1024 resolution is  
> already to
> the limits of our ability to "feel" any difference where as the
> speed/latency was much more noticable.   Cost does come into the  
> equation
> such that for a $500 radio, they couldn't do both.
>
> 1024 resolution provides better than 1/10deg at 90 deg of rotation.   
> That's
> less than 1/1000" on a 1" servo wheel.
>
> The speed on the other hand is just now approaching our limits of  
> "feel".
> The faster systems clearly feel more connected and are noticable  
> when flying
> Snaps and other rapid input maneuvers and especially flying 3D with  
> the
> helis.
>
> So the choice was to invest in a fast response system with 1024  
> resolution.
>
>
> Does anyone know the tolerances of our servo accuracy?  I'd be  
> curious to
> know how high a resolution they can accurately replicate.
>
> Mike?  Any input from the source?
>
> -Mark
> --------------------------
> Sent from my BlackBerry Wireless Handheld
>
>
> ----- Original Message -----
> From: nsrca-discussion-bounces at lists.nsrca.org
> <nsrca-discussion-bounces at lists.nsrca.org>
> To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org>
> Sent: Mon Aug 24 15:30:03 2009
> Subject: [NSRCA-discussion] SD-10
>
> Hi Anthony, Jim, Mark , and Others who Responded,
>
>
>
> Thanks for your valuable input. I've read that this radio's  
> resolution is or
> is among the very  fastest; so much so that even digital servos  
> can't keep
> up with it. I understand  that the system is 1024 , but can't help but
> wonder why it isn't 2048. I'm sure I'll get past my  hangup, but would
> appreciate everyone's insight's on that one.
>
>
>
> Thanks,
>
> Frank Imbriaco
>
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