Gr_fractional_interpolator interpolation ratio

GNU Radio
1

This might be a silly question. But here goes …

In gr_fractional_interpolator_ff I observed that to make the filter
interpolate between input values you have to set the interpolation ratio
< 1
and this is because the block has this line in the code
“set_relative_rate
(1.0 / interp_ratio)”. I always thought for a block named interpolator a
value of interpolation_ratio > 1 would be understood as increasing the
sampling rate by that factor. Is this not correct?

Karthik

2

On Wed, 2009-07-22 at 18:22 -0700, Karthik wrote:

In gr_fractional_interpolator_ff I observed that to make the filter
interpolate between input values you have to set the interpolation
ratio < 1 and this is because the block has this line in the code
“set_relative_rate (1.0 / interp_ratio)”. I always thought for a block
named interpolator a value of interpolation_ratio > 1 would be
understood as increasing the sampling rate by that factor. Is this not
correct?

No, you’re right. It’s a historical feature frozen in to place by lots
of code using that block constructor.

There’s some new fractional interpolator code on the way and it will be
named right this time :slight_smile:

Johnathan