Default value of "Taps" in GRC

GNU Radio
1

The XML for filter_rational_resampler_xxx sets the default value of Taps
to
None. However, this gives the error Expression “[None]” is invalid for
type
complex vector.

Deleting “None” from this box fixes the problem. Is it safe to change my
XML definition to have no default value?

2

On Thu, Jul 4, 2013 at 7:50 PM, Stephen Harrison
[email protected] wrote:

The XML for filter_rational_resampler_xxx sets the default value of Taps to
None. However, this gives the error Expression “[None]” is invalid for type
complex vector.

Deleting “None” from this box fixes the problem. Is it safe to change my XML
definition to have no default value?

Stephen,

There is a bug filed on our Redmine Issues page about the use of ‘[’
and ‘]’ on different systems. I think this might be the same problem
you’re seeing with the ‘[None]’ instead of just ‘None’.

The rational_resampler is a hier_block2 (in gr-filter/python/filter),
and if you tell it the taps are None, it will automatically calculate
a set of taps for you. It makes an allpass filter for the original
signal.

Off the top of my head, I’m not sure what happens if you leave this
block empty. It might be fine since the taps argument for this block
has a default of ‘None’, or it might think that the you are passing an
empty list of taps, in which case it wouldn’t be correct. You can
easily test this by using the rational_resampler block as an integer
upsampler and looking at the output. If you see big images that aren’t
being supressed, you aren’t filtering.

My guess is that the latter is happening. If ‘None’ is being read as
‘[None]’, then I think ‘’ will become ‘[]’.

Tom