Re: [Discuss-gnuradio] Error in Interpolating FIR filter

[Manu T S]

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 7:26 PM, Tom Rondeau <address@hidden> wrote:

On Fri, Apr 5, 2013 at 9:01 AM, Brian Padalino <address@hidden> wrote:
> On Fri, Apr 5, 2013 at 8:29 AM, Tom Rondeau <address@hidden> wrote:
>>
>> On Fri, Apr 5, 2013 at 1:31 AM, Manu T S <address@hidden> wrote:
>> > 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 <module>
>> >     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.
>> >
>> >
>> >
>> > --
>> > 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

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

--
Manu T S