Is there a generic way to name what are usually the 'time' and 'frequency' domains for digital filtering? I seek a single term that can be applied for instance when the data to be filtered may be a (frequency) spectrum, or spatial positions, or angles. Chris ============================= Chris Bore BORES Signal Processing www.bores.com
Generic name for time and frequency in filtering?
Started by ●January 12, 2010
Reply by ●January 12, 20102010-01-12
On 12 Jan, 14:52, Chris Bore <chris.b...@gmail.com> wrote:> Is there a generic way to name what are usually the 'time' and > 'frequency' domains for digital filtering? > > I seek a single term that can be applied for instance when the data to > be filtered may be a (frequency) spectrum, or spatial positions, or > angles.I'd suggest 'Measured Domain' and 'Transformed Domain'. Rune
Reply by ●January 12, 20102010-01-12
>I seek a single term that can be applied for instance when the data to >be filtered may be a (frequency) spectrum, or spatial positions, or >angles.I've seen references to "data domain" and "transform domain". Greg
Reply by ●January 12, 20102010-01-12
On Jan 12, 8:52=A0am, Chris Bore <chris.b...@gmail.com> wrote:> Is there a generic way to name what are usually the 'time' and > 'frequency' domains for digital filtering? > > I seek a single term that can be applied for instance when the data to > be filtered may be a (frequency) spectrum, or spatial positions, or > angles.this isn't really the answer to your question but instead of "frequency domain", i sometimes say "reciprocal-<unit> domain". but, i remember once having trouble explaining what little i knew about image processing. can't remember what i called the x and y axis of the pic. "length domain" or more likely "position domain", i dunno. but i called the other one the "frequency domain" and that didn't make sense (if we got careless with units) so i called it "reciprocal-position" or something like that. r b-j
Reply by ●January 12, 20102010-01-12
robert bristow-johnson wrote:> On Jan 12, 8:52 am, Chris Bore <chris.b...@gmail.com> wrote: >> Is there a generic way to name what are usually the 'time' and >> 'frequency' domains for digital filtering? >> >> I seek a single term that can be applied for instance when the data to >> be filtered may be a (frequency) spectrum, or spatial positions, or >> angles. > > this isn't really the answer to your question but instead of > "frequency domain", i sometimes say "reciprocal-<unit> domain". > > but, i remember once having trouble explaining what little i knew > about image processing. can't remember what i called the x and y axis > of the pic. "length domain" or more likely "position domain", i > dunno. but i called the other one the "frequency domain" and that > didn't make sense (if we got careless with units) so i called it > "reciprocal-position" or something like that."Spatial frequency" is widely used. "Wave number" seems too abstruse to me. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 12, 20102010-01-12
On 13 Jan, 04:06, Jerry Avins <j...@ieee.org> wrote:> robert bristow-johnson wrote: > > On Jan 12, 8:52 am, Chris Bore <chris.b...@gmail.com> wrote: > >> Is there a generic way to name what are usually the 'time' and > >> 'frequency' domains for digital filtering? > > >> I seek a single term that can be applied for instance when the data to > >> be filtered may be a (frequency) spectrum, or spatial positions, or > >> angles. > > > this isn't really the answer to your question but instead of > > "frequency domain", i sometimes say "reciprocal-<unit> domain". > > > but, i remember once having trouble explaining what little i knew > > about image processing. =A0can't remember what i called the x and y axi=s> > of the pic. =A0"length domain" or more likely "position domain", i > > dunno. =A0but i called the other one the "frequency domain" and that > > didn't make sense (if we got careless with units) so i called it > > "reciprocal-position" or something like that. > > "Spatial frequency" is widely used."Spatial frequency" seems to be universally useful - if not always easily understandable - for data where at least one dimension of the data is spatial...> "Wave number" seems too abstruse to me....whereas "wavenumber" seems to be used more or less exclusively in the context of PDEs where at least one dimension is spatial. Rune
Reply by ●January 13, 20102010-01-13
On Jan 12, 7:14=A0pm, Rune Allnor <all...@tele.ntnu.no> wrote:> ... > ...whereas "wavenumber" seems to be used more or less exclusively > in the context of PDEs where at least one dimension is spatial. > > RuneA wavenumber spectrum is the result of the fft of a set of uniformly linearly spaced spatial samples. For some choices of sample interval, array size and transform size the 'wavenumber' spectrum may be equivalent to 'beam' spectrum for narrow frequency bands. 'wavenumber' finds common usage in beamforming. Consider the two examples I gave back in October when Chris had a related question: http://groups.google.com/group/comp.dsp/browse_thread/thread/73cd21612e98ce= 1b/cce2c5d85c9014f2?hl=3Den&lnk=3Dgst&q=3Dfrequency+beamforming#cce2c5d85c9= 014f2 A wavenumber-frequency spectrum is often interpolated to a beam- frequency spectrum. WSRL-0162-TR at: http://hdl.handle.net/1947/8750 ADA394281.pdf at: http://handle.dtic.mil/100.2/ADA394281 Title: Derivation of Beam Interpolation Coefficients with Application to the K-omega Beamformer Dale B. Dalymple
Reply by ●January 13, 20102010-01-13
Jerry Avins <jya@ieee.org> wrote: (snip, someone wrote)>> but, i remember once having trouble explaining what little i knew >> about image processing. can't remember what i called the x and y axis >> of the pic. "length domain" or more likely "position domain", i >> dunno. but i called the other one the "frequency domain" and that >> didn't make sense (if we got careless with units) so i called it >> "reciprocal-position" or something like that.> "Spatial frequency" is widely used. "Wave number" seems too > abstruse to me.Wave vector in more than one dimension. It also has the 2pi that frequency doesn't normally have. (Angular frequency does.) The Wave number is 2 pi/wavelength. In a dispersive medium, but not too dispersive, w/k is the phase velocity, dw/dk the group velocity. (w is omega, angular frequency, I don't have an actual omega on this news reader.) As I understand it, part of the reason was that in the early days of spectroscopy c wasn't so accurately known, so reciprocal wavelength was used instead. (Proportional to energy, but avoids c before c was defined.) -- glen
Reply by ●January 13, 20102010-01-13
On 13 Jan, 05:14, dbd <d...@ieee.org> wrote:> On Jan 12, 7:14=A0pm, Rune Allnor <all...@tele.ntnu.no> wrote: > > > ... > > ...whereas "wavenumber" seems to be used more or less exclusively > > in the context of PDEs where at least one dimension is spatial. > > > Rune > > A wavenumber spectrum is the result of the fft of a set of uniformly > linearlyAre you excluding non-uniform and / or non-linear spatial samples from the definition?> spaced spatial samples.Do you agree that CCDs produce 'spatial samples' of intensity? If so, can you demonstrate that the term 'wavenumber' is used in the context of image processing? Rune
Reply by ●January 13, 20102010-01-13
On Jan 12, 9:18=A0pm, Rune Allnor <all...@tele.ntnu.no> wrote:> On 13 Jan, 05:14, dbd <d...@ieee.org> wrote: > ... > > A wavenumber spectrum is the result of the fft of a set of uniformly > > linearly > > Are you excluding non-uniform and / or non-linear spatial > samples from the definition?I've only said that usual definition of the fft produces a wavenumber spectrum from uniform samples, other calculations can transform nonuniform samples to a wavenumber spectrum. I've given an example of a common practice in the sonar community with examples from the navies of two nations.> > > spaced spatial samples. > > Do you agree that CCDs produce 'spatial samples' of intensity?Agree with whom about what? Are you claiming that CCDs produce the coherent samples that would be required to be appropriate to the coherent processes discussed in this thread?> If so, can you demonstrate that the term 'wavenumber' is used > in the context of image processing?What would that have to do with the content of this thread? What would that have to do with whether 'wavenumber' is commonly used in coherent sonar processing as well as in PDEs?> > RuneDale B. Dalrymple
