Re: storage of sensor data with Fourier transforms

On 5/5/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> "Nathan Buchanan" <nbinont(at)gmail(dot)com> writes:
> > I had the idea of taking the Fourier transform of the waveform and
> storing
> > the waveform internally that way to reduce storage requirements.
>
> Aside from what Steve said: The Fourier transform in itself doesn't
> reduce data size --- it's N points in, N points out. If you want to
> reduce storage requirements you have to resort to lossy compression, ie,
> deliberately throwing away some data. The transformed data might be
> more suitable for doing that (eg you can selectively discard
> high-frequency components) but do you really want to? Usually the point
> of storing measurements is so you can do unspecified analysis on them
> later. Applying lossy compression will restrict what you can
> (meaningfully) do later on.
>
> regards, tom lane
>

Thanks for the replies. It seems I need to examine my plan more closely.

Nathan