Gr-buffer usage

GNU Radio
1

hi,
can anyone point me towards some example code using gr-buffer?
I need to read a sample stream from HD (not very fast…)
and afterwards re send it towards the usrp significantly faster
(8complex
Msps).
is gr-buffer a good candidate to do this?

thanks

2

2007/7/19, Vincenzo P. [email protected]:

hi,
can anyone point me towards some example code using gr-buffer?
I need to read a sample stream from HD (not very fast…)
and afterwards re send it towards the usrp significantly faster (8complex
Msps).
is gr-buffer a good candidate to do this?

You could either use gr.file_source_x or gr.vector_source_x.

–
Trond D.

3

thanks Trond,
I went your way, and actually my stream gets loaded right into the ram
as I wanted…:slight_smile:
my problem is now that… doing:

    data = fromfile("/root/Desktop/ofdm_encode_1H.dump",

dtype=“complex64”)
vector_source = gr.vector_source_c(data,True)

    self.connect(vector_source,gain)
    self.connect (gain, self.u)

I get an error relating to the number of arguments I pass to
gr.vector_source_c

vector_source = gr.vector_source_c(data,True)

File
“/usr/local/lib/python2.4/site-packages/gnuradio/gr/gnuradio_swig_py_gengen.py”,
line 6695, in vector_source_c
return _gnuradio_swig_py_gengen.vector_source_c(*args)
NotImplementedError: Wrong number of arguments for overloaded function
‘vector_source_c’.
Possible C/C++ prototypes are:

gr_make_vector_source_c(std::vector<gr_complex,std::allocator<gr_complex

const &,bool)

gr_make_vector_source_c(std::vector<gr_complex,std::allocator<gr_complex

const &)

what am I doing wrong?

sorry for bothering…
and thanks for help

vincenzo

4

2007/7/19, Vincenzo P. [email protected]:

anything like:

gr.file_source—>data=gr.vector_sink
gr.vector_source(data, repeat=true)—>usrp_sink

would be correct?

No, if you use vector_source, you should not use the gr.file_source to
load the data. How you read the data from the file depends on the
format is is stored in, but if it data recorded with GNU Radio, I
personally use numpy/scipy. Python example:

from numpy import *

Use complex64 for gr.gr_complex and float32 for gr.float

data = fromfile(“filename.dat”, dtype=“complex64”)
src = gr.vector_source(data, repeat=True)

5

i think my problem is that numpy’s fromfile() provides this as an output

[ -1.38586906e+38 +1.12948992e+32j 1.43605805e+30 -4.40817649e-09j
8.78218944e+08 -1.98631123e-14j …, 4.88822397e+23 +2.90330289e
+13j
5.91237359e-02 +4.88047634e+23j -5.31466166e+33 -3.25484218e-18j]

which gets refused from gr.vector_source

instead of this

[ -1.38586906e+38 +1.12948992e+32j , 1.43605805e+30 -4.40817649e-09j
8.78218944e+08 -1.98631123e-14j , 4.88822397e+23 +2.90330289e+13j
5.91237359e-02 +4.88047634e+23j , -5.31466166e+33 -3.25484218e-18j]

which works fine.

I haven’t been able to find much documentation about numpy so I don’t
know how to convert between these data types…

does anyone know where to look?

thanks

vincenzo

6

2007/7/24, Eric B. [email protected]:

    self.connect(vector_source,gain)

‘vector_source_c’.

sorry for bothering…
and thanks for help

vincenzo

What is the type of the “data” result?

The type of data is a numpy array. It can be converted to an ordinary
python list:

a_list = data.tolist()

However, whenever a list is expected, a numpy array can always be used.

vector_source_c expects a Python list or tuple of complex.

–
Trond D.

7

On Wed, Jul 25, 2007 at 12:14:42PM +0200, Vincenzo P. wrote:

but what is the usual good way in gnuradio to fill a vector with data
from files?
is there an alternative to this?
the only thing I need is to set up my vector source for feeding the usrp
with samples

If you’re reading binary data from files, the usual way it to just
use gr.file_source(gr.sizeof_gr_complex, ‘my-filename’)

Eric

8

On Tue, Jul 24, 2007 at 12:36:10PM +0200, Vincenzo P. wrote:

thanks Trond,
I went your way, and actually my stream gets loaded right into the ram
as I wanted…:slight_smile:
my problem is now that… doing:

    data = fromfile("/root/Desktop/ofdm_encode_1H.dump",

dtype=“complex64”)
vector_source = gr.vector_source_c(data,True)

You might want to try dtype=“complex32”

Eric

9

On Tue, Jul 24, 2007 at 12:36:10PM +0200, Vincenzo P. wrote:

    self.connect (gain, self.u)

Possible C/C++ prototypes are:
sorry for bothering…
and thanks for help

vincenzo

What is the type of the “data” result?
vector_source_c expects a Python list or tuple of complex.

Eric

10

my fromfile (file, dtype) numpy function does not accept d type =
complex32…

data = fromfile("/root/Desktop/rx.dat", dtype="complex32")

TypeError: data type not understood

but what is the usual good way in gnuradio to fill a vector with data
from files?
is there an alternative to this?
the only thing I need is to set up my vector source for feeding the usrp
with samples

thanks Eric

vincenzo

11

2007/7/25, Vincenzo P. [email protected]:

[ -1.38586906e+38 +1.12948992e+32j , 1.43605805e+30 -4.40817649e-09j
8.78218944e+08 -1.98631123e-14j , 4.88822397e+23 +2.90330289e+13j
5.91237359e-02 +4.88047634e+23j , -5.31466166e+33 -3.25484218e-18j]

which works fine.

I haven’t been able to find much documentation about numpy so I don’t
know how to convert between these data types…

does anyone know where to look?

–
Trond D.