[LinuxUsers] more Re: Sine wave vs shaped square wave

[Chris Penn]

Yay, calculus on the LUG list!

Yes.
There are several ways to approximate that kind of error, aka a
remainder term.  Taylor series expansion comes to mind.  Bump
functions or  possibly regression of some form or another.  I'm not
sure which function you want to compare sine to; a function and its
parameters tend to dictate which approximation and error term you use.
 I think I heard box or square wave, maybe some Fourier Series action
might be useful (http://bit.ly/aonDK).  With something as popular as
electronics, I would suspect such a calculation has been made, if it
is useful.

Chris...


On Thu, Jun 4, 2009 at 7:29 AM, David Kaiser <dkaiser at cdk.com> wrote:
> So, then, maybe the question should be:  To what degree or resolution is
> the "stepping" or "squareness" permittable.  Is there some calculus
> or something that I can use to say "this much" approximation is as
> good as a mathematically pure sine wave?
>
> On 6/4/2009, "Todd Lyons" <tlyons at ivenue.com> wrote:
>
>>On Wed, Jun 3, 2009 at 6:34 PM, Jeff Lasman <jplists at nobaloney.net> wrote:
>>> Good info here:
>>> http://sci.tech-archive.net/Archive/sci.electronics.design/2005-02/5165.html
>>> But that was 2005, this is 2009, and UPSes using stepped square waves
>>> come with $10,000 equipment warranty.
>>> So have things (like design issues) fundamentally changed?
>>
>>Everything modern uses high frequency switching power supplies (unless
>>you're like Gibson and got a PDP-8 :-).  So when you talk about
>>stepped square waves, are you talking about PWM (Pulse Width
>>Modulated) output?  That's par for the course nowadays.
>>
>>--
>>Regards...      Todd
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