[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Discuss-gnuradio] gr_firdes_bandpass()
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] gr_firdes_bandpass() |
Date: |
Wed, 13 May 2009 12:53:30 -0700 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Wed, May 13, 2009 at 03:40:31PM -0400, Marcus D. Leech wrote:
> I don't understand why this is failing:
>
> Traceback (most recent call last):
> File "./top_block.py", line 184, in <module>
> tb = top_block(options)
> File "./top_block.py", line 97, in __init__
> 1, bw, -7.0, 7.0, 150, firdes.WIN_HAMMING, 6.76))
> File
> "/usr/local/lib/python2.5/site-packages/gnuradio/gr/gnuradio_swig_py_general.py",
> line 2729, in band_pass
> return _gnuradio_swig_py_general.firdes_band_pass(*args, **kwargs)
> IndexError: gr_firdes check failed: 0 < fa <= sampling_freq / 2
>
>
> When I specify negative frequencies, it does this.
>
> I thought that with a complex filter, I could specify negative frequency?
>
> This particular filter is a decimating filter that is decminating from
> 500KHz sample rate down to 32KHz sample rate,
> with cutoff between -7KHz and +7KHz. But I'm triggering this error,
> and I don't understand why. This is from
> a GRC flow-graph.
>
Just use a low pass (0 .. 7k). No need for the bandpass.
firdes_band_pass (and the lowpass for that matter) design real filters
coeffs that you can use with gr.fir_filter_ccf.
Eric