[time-nuts] Re: pulling some crystals

[Andy Talbot]

https://dspguru.com/dsp/faqs/cordic/

Andy
www.g4jnt.com



On Sat, 30 Dec 2023 at 20:44, Jim Lux via time-nuts <
time-nuts at lists.febo.com> wrote:

>
>
>
>
> Generically, this is known as the Cordic method.
> There are some techniques for managing the truncation error and magnitude
> that Detlef mentions, but I can’t remember them off the top of my head. I’m
> sure they’re in the literature. The trick is in making them simple and
> deterministic in time.
>
>
> On Fri, 29 Dec 2023 12:28:20 +0100, dschuecker via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
> Hi,
>
> I generate Sin/Cos without a table by rotating complex numbers
> (a+i*b)*(u+i*v)
>
> a,b,u,v may be 16Bit integers, for most appplications this prooved
> sufficient for me. a is the cos-component, b is the sine component.
> (a+i*b) is rotated by the angle of (u+i*v). For integer calculation
> |u+i*v| = sqrt(u*u+v*v) is normalized to ,say 2^16 and followed by a
> rightshift of 16Bit. It is necessary to watch |a+i*b|=sqrt(a*a+b*b)
> because vectorlength is shrinking or expanding due to calculation noise.
>
> Cheers Detlef
>
>
>
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