Re: [Discuss-gnuradio] File format question

[Dan Halperin]

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Bahn William L Civ USAFA/DFCS wrote:
> Thanks, that helps some.
> 
> I figured that I could put in the literal size of the data, in bytes, but 
> that only helps if it actually matches how the GR blocks are going to process 
> those bytes.
> 
> When possible, I would prefer to use the constants that have been set up so 
> that the code is (1) more readable, and (2) more maintainable. So instead of 
> using "8" for complex, I would like to use gr.sizeof_"whatever". But I don't 
> know what "whatever" needs to be. Where do I find this?
> 
> I'll look at dbpsk.py and tunnel.py when I get my Linux box set back up. Is 
> there a module that takes time domain data and converts it to IQ pairs, or am 
> I responsible for doing that when I generate the file? If so, what LO 
> frequency would I need to use?
> 
> It would be so much simpler if I could just use the generated time domain 
> data directly.
> 
> Thanks!

From
/usr/local/lib/python2.5/site-packages/gnuradio/gr/gnuradio_swig_py_runtime.py:

sizeof_char = _gnuradio_swig_py_runtime.sizeof_char
sizeof_short = _gnuradio_swig_py_runtime.sizeof_short
sizeof_int = _gnuradio_swig_py_runtime.sizeof_int
sizeof_float = _gnuradio_swig_py_runtime.sizeof_float
sizeof_double = _gnuradio_swig_py_runtime.sizeof_double
sizeof_gr_complex = _gnuradio_swig_py_runtime.sizeof_gr_complex

Those are the constants you want.

When you say generated time domain data, are you talking about (time,
voltage) pairs off of a scope? IIRC scope data is just the I component,
and you can get the Q component from I using standard signal processing
techniques assuming your sampling rate is sufficiently high.

- -Dan
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