Error in Interpolating FIR filter

Executing the attached flow graph I get the following error.

#####################################################################################

gr_fir_ccc: using SSE
Traceback (most recent call last):
File “/home/manu/coding/top_block.py”, line 72, in
tb.Run(True)
File
“/usr/local/lib/python2.7/dist-packages/grc_gnuradio/wxgui/top_block_gui.py”,
line 76, in Run
self.start()
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/gr/top_block.py”,
line 97, in start
self._tb.start(max_noutput_items)
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gnuradio_core_runtime.py”,
line 3077, in start
return _gnuradio_core_runtime.gr_top_block_sptr_start(self,
max_noutput_items)
RuntimeError: gr_buffer_add_reader: nzero_preload must be >= 0
#######################################################################################

What could be the possible reason?

I have installed using build-gnuradio script on day before yesterday.

On Fri, Apr 5, 2013 at 1:31 AM, Manu T S [email protected] wrote:

self.start()

What could be the possible reason?

I have installed using build-gnuradio script on day before yesterday.


Manu T S

Manu,

You have to give the interpolator taps. It can’t run without a filter
defined.

Tom

On Fri, Apr 5, 2013 at 8:29 AM, Tom R. [email protected] wrote:

return _gnuradio_core_runtime.gr_top_block_sptr_start(self,


Manu T S

Manu,

You have to give the interpolator taps. It can’t run without a filter
defined.

The error message could definitely be much better.

“RuntimeError: gr_buffer_add_reader: nzero_preload must be >= 0”

Even to an experienced person, without seeing the flow graph, that error
doesn’t mean anything. Debugging a large flow graph might be like
looking
for a needle in a haystack.

As a side note, what error gets thrown when this is in a straight C++
application? Is it more informative or equally as ambiguous?

Is it possible to get the filter to throw the assertion/error versus the
runtime?

Brian

Thanks everyone.

It worked when I set the taps. I was confused because from what I
remember
I have used these blocks previously without specifying the taps.

I also noticed that if I use a polyphase resampler instead of
interpolating
filter, the scope does not pope up. It just says excuting and then done.
It
didn’t through any error. Again it worked when I set the taps.

On Fri, Apr 5, 2013 at 9:01 AM, Brian P. [email protected]
wrote:

tb.Run(True)

I have installed using build-gnuradio script on day before yesterday.

application? Is it more informative or equally as ambiguous?

Is it possible to get the filter to throw the assertion/error versus the
runtime?

Brian

I was wondering who was going to ask that question first. But that’s
what I get for answering email before my coffee.

Strangely, there is no error generated by the class for this case. I’m
adding one now. If no taps are provided, it will throw a runtime_error
that tells you a bit more what’s going on.

Tom

On Fri, Apr 5, 2013 at 1:01 PM, Manu T S [email protected] wrote:

Thanks everyone.

It worked when I set the taps. I was confused because from what I remember I
have used these blocks previously without specifying the taps.

I also noticed that if I use a polyphase resampler instead of interpolating
filter, the scope does not pope up. It just says excuting and then done. It
didn’t through any error. Again it worked when I set the taps.

I have a patch for that error. Will hopefully push it today.

Tom