Eric Chassande-Mottin wrote:
>> Cute, and I can see the use of such a function for clock offset
> calculations in comms systems. I
>> typically use simpler narrwband approximations for this functionality as I
>> have to worry about how
>> to implement it on an ASIC.
>
> good to know that this work could be useful elsewhere!
>
>> The interpolator must introduce a colored noise to the signal, that
>> depends on the signal given to
>> the function, and the characteristics of the interpolating filter. Have
>> you any idea of the magnitude
>> of the error introduced with the default filter? If so it would probably
>> makes sense to document it in
>> the help string so that others kno what to expect. I'd check myself, but
>> am writing from an EEE PC
>> without a copy of Octave installed to check with.
>
> the parameter log10_rejection determines the interpolation error in
> the working band of the interpolator. if you make a script with the
> first test and plot the variable "err", you'll have a practical demo
> of the interpolation error. in this test, a sinusoid is shifted first
> with this code and second using the exact expression. the two
> are then compared. the third test is a similar test for random noise.
Can't this be a parameter of the function? Say if the third argument is
a vector it is treated as the interpolator, and if its a scalar its
treated as the rejection. The log10_rejection default value is -3,
though it seems that is later multiplied by -20 to give a 60dB
rejection. Why just have the value to 60 instead?
>
> I am not sure how to document that in the help message since
> the value of log10_rejection is hard wired. A note in the code
> might be a better idea?
If the above change is acceptable then why not something like
## -*- texinfo -*-
## @deftypefn {Function File} [EMAIL PROTECTED], @var{h}] =} fracshift (@var{x},
@var{d})
## @deftypefn {Function File} [EMAIL PROTECTED], @var{h}] =} fracshift (@var{x},
@var{d}, @var{rej})
## @deftypefnx {Function File} [EMAIL PROTECTED] =} fracshift (@var{x}, @var{d},
@var{h})
## Shift the series @var{x} by a (possibly fractional) number of samples
## @var{d}.
##
## If the third argument @var{h} is a vector it defines the interpolator,
## otherwise the interpolator is constructed with a Kaiser-windowed sincard.
## The acceptable error of the window function is determined by @var{rej},
## which by default is 60, representing an acceptable error in the
## interpolation of -60dB. If the third argument is scalar then it
determines
## this rejection.
## @end deftypefn
## @seealso{circshift}
>
>> seems like a good thing. I'd say go ahead and commit it.
>
> OK, done with the change in the copyright/help
> but I have a problem here. I could svn add the source but
> svn refuses to commit (see message which I don't understand).
> right access problem? am I missing something?
>
> octave-forge/main/signal/inst$ svn status
> A fracshift.m
> octave-forge/main/signal/inst$ svn ci fracshift.m -m"first import"
> svn: Commit failed (details follow):
> svn: Server sent unexpected return value (403 Forbidden) in response to
> MKACTIVITY request for
> '/svnroot/octave/!svn/act/d893d539-3913-4ddc-ada4-448b62242a57'
>
> eric
Not sure of the reason. Probably a transient issue with sourceforge.
Give it a few hours then try again..
D.
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