Forum: GNU Radio gr_fractional_interpolator.i missing, does anybody have it

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3719f4fea703e38bcbf8de6fe6bcdf55?d=identicon&s=25 Martin Dvh (Guest)
on 2007-03-09 19:05
(Received via mailing list)
I would like to use gr_fractional_interpolator
But I get:
    self.interp=gr.fractional_interpolator(
options.phase_shift,interp_ratio)
AttributeError: 'module' object has no attribute
'fractional_interpolator'

Apparantly the module doesn't exist anymore, although
gr_fractional_interpolator.h and gr_fractional_interpolator.cc exist.

I suspect there should also be a:
gr_fractional_interpolator.i

But I couldn't find it in my source or any of the older gnuradio
releases I have laying around.

I know there is a rational_resampler in gnuradio now, but there you have
to give your interpolator taps.
The good thing of gr_fractional_interpolator is that it uses
mmse_fir_interpolator which has optimized performance for
low-tap-numbers.

Could anybody tell me how to get gr_fractional_interpolator to work or
where gr_fractional_interpolator.i is.

Greetings,
Martin
D0072e69d706bb3ca211d33a1b536e2c?d=identicon&s=25 Johnathan Corgan (Guest)
on 2007-03-12 19:16
(Received via mailing list)
Martin Dvh wrote:

> Apparantly the module doesn't exist anymore, although
> gr_fractional_interpolator.h and gr_fractional_interpolator.cc exist.
>
> I suspect there should also be a: gr_fractional_interpolator.i
>
> But I couldn't find it in my source or any of the older gnuradio
> releases I have laying around.

It doesn't appear to have ever existed, as far as I can tell.
Everywhere fractional interpolation is used in the tree, the low-level
gri_mmse_fir_interpolator implementation is used.

The gr_ wrapper does look functional, but I just spotted a bug in its
constructor, so it looks like a work-in-progress that never got
finished.

> Could anybody tell me how to get gr_fractional_interpolator to work
> or where gr_fractional_interpolator.i is.

I'll add getting this to work to my queue :-)

--
Johnathan Corgan
Corgan Enterprises LLC
http://corganenterprises.com
3719f4fea703e38bcbf8de6fe6bcdf55?d=identicon&s=25 Martin Dvh (Guest)
on 2007-03-12 21:02
(Received via mailing list)
Johnathan Corgan wrote:
>
>
> It doesn't appear to have ever existed, as far as I can tell.
> Everywhere fractional interpolation is used in the tree, the low-level
> gri_mmse_fir_interpolator implementation is used.
>
> The gr_ wrapper does look functional, but I just spotted a bug in its
> constructor, so it looks like a work-in-progress that never got finished.
Yes, I spotted it too now:
   d_mu (phase_shift), d_mu_inc (interp_ratio), d_interp()
should be
   d_mu (phase_shift), d_mu_inc (interp_ratio), d_interp(new
gri_mmse_fir_interpolator())
>
>
>>Could anybody tell me how to get gr_fractional_interpolator to work
>>or where gr_fractional_interpolator.i is.
>
>
> I'll add getting this to work to my queue :-)
I don't mind getting it to work myself.
I just don't like inventing the wheel twice.

I will try to get it to work in my tree
branches/developers/nldudok1/general-wip

and let you know when its done.

Greetings,
Martin
D0072e69d706bb3ca211d33a1b536e2c?d=identicon&s=25 Johnathan Corgan (Guest)
on 2007-03-12 21:17
(Received via mailing list)
Martin Dvh wrote:

> Yes, I spotted it too now:
>    d_mu (phase_shift), d_mu_inc (interp_ratio), d_interp()
> should be
>    d_mu (phase_shift), d_mu_inc (interp_ratio), d_interp(new 
gri_mmse_fir_interpolator())

Yes.

> I will try to get it to work in my tree
> branches/developers/nldudok1/general-wip

My plan was to rename the existing one and create a second one, so we'd
have:

gr_fractional_interpolator_ff   (the current one)
gr_fractional_interpolator_cc   (the new one that does complex samples)

That will require some changes to the gri_mmse* code.

If you want to do this, have fun :-)

--
Johnathan Corgan
Corgan Enterprises LLC
http://corganenterprises.com
745d8202ef5a58c1058d0e5395a78f9c?d=identicon&s=25 Eric Blossom (Guest)
on 2007-03-12 21:26
(Received via mailing list)
On Fri, Mar 09, 2007 at 07:04:06PM +0100, Martin Dvh wrote:
> I would like to use gr_fractional_interpolator
> But I get:
>     self.interp=gr.fractional_interpolator( options.phase_shift,interp_ratio)
> AttributeError: 'module' object has no attribute 'fractional_interpolator'
>

> Apparantly the module doesn't exist anymore, although
> gr_fractional_interpolator.h and gr_fractional_interpolator.cc
> exist.
>

> I suspect there should also be a:
> gr_fractional_interpolator.i

This was apparently never finished or tested.
I understand that Johnathan has a patch that will fix this.
The underlying code is known to work.

> But I couldn't find it in my source or any of the older gnuradio
> releases I have laying around.

> I know there is a rational_resampler in gnuradio now, but there you
> have to give your interpolator taps.

Actually, if you use blks.rational_resampler_fff it'll design an
appropriate filter for you.  See
gnuradio-examples/python/audio/test_resampler.py


> The good thing of gr_fractional_interpolator is that it uses
> mmse_fir_interpolator which has optimized performance for
> low-tap-numbers.

> Could anybody tell me how to get gr_fractional_interpolator to work
> or where gr_fractional_interpolator.i is.

> Greetings,
> Martin

Eric
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