[Discuss-gnuradio] Re: sending signal to soundcard

[address@hidden]

On Thu, Aug 04, 2005 at 02:33:18PM +0930, Choon Ho wrote:
> Quoting Choon Ho <address@hidden>:
> 
> Hello folks
> 
> I v got 2 unit of USRP, and i am writing my own polyphase filter code to
> recieve
> AM signal. I am now stuck on how to get the filtered signal (an array of
> signal)
> to the sound card? I hv attached my code, and would appreciate if soume one
> could just give me some advise. Or sent me some examples.
> 
> The signal i want to sent to the sound card is named "output", at the last
> line
> of the code.
> 
> Thanking u in advance
> Johnny Ho

Please take a look at the examples in gnuradio-examples

Start with gnuradio-examples/python/audio/dial_tone.py

FYI, GNU Radio already contains high performance polyphase filtering
code.  Take a look at gr.fir_filter_??? where ??? indicates the type
of the input, output and taps respectively.  f = float, c = complex

I also suggest that you start with:

  http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html

Be sure that you understand the flow graph and signal processing block
concepts.

Eric

> # start of my program
> #!/usr/bin/env python
> 
> import numarray
> from numarray import*
> from gnuradio import gr, eng_notation
> 
> # from gnuradio import usrp
> from gnuradio.eng_option import eng_option
> from optparse import OptionParser
> import sys
> import math
> 
> def FIR_filter(sig,coef):
> 
> # #### FIR FILTER ####
>       print "the signal:", sig, "the coef:",coef
> 
>       filter_out = zeros((size(sig)))
>       print shape(filter_out)
>       print "newly created",filter_out
> 
>       buff_len = size(sig)
>       coeff_len = size(coef)
>       filter_len = buff_len - coeff_len
>       print "filter_len = ", filter_len
>       L = 0
> 
>       print "coef len", coeff_len, "buff_len", buff_len,"filter_len:",
> filter_len
> 
>       for x in range(filter_len+1): # loop 3x
>               tmp = 0
>               curr_tmp = 0
>               final_tmp = 0
>               K = 0
> 
>               for n in range(coeff_len):  # loop 2x
>                       print "coef(n):",coef[n],"sig(n):",sig[L + (size(coef)-
> 1) - K], "x loop =", x, "n loop = ", n
> 
>                       curr_tmp = coef[n] * sig[L + (size(coef)-1) - K]
>                       final_tmp = tmp + curr_tmp
>                       tmp = final_tmp
>                       K = K + 1
>               L = L + 1
>               filter_out[x] = final_tmp
>       print "after compute",filter_out
>       return (filter_out)
> 
> 
> M=3
> 
> # reshape coeff
> h = array([1, 2, 3]);
> print h
> z1 = concatenate(zeros((1,M-1)),1);
> print z1
> h_pad = concatenate((z1,h),1);
> print h_pad
> 
> if len(h_pad)%M !=0:
>       z1=concatenate(zeros((1,M-(len(h_pad)%M))))
>       h_pad=concatenate((h_pad,z1),1)
> 
> h_mat = reshape(h_pad,(len(h_pad)/M,M))
> print h_mat
> h_tran = transpose(h_mat)
> print h_tran
> h_flip = h_tran[::-1]
> print h_flip
> 
> # reshape sig
> sig_new = array([1, 2, 3, 4, 5, 6, 7, 8, 9, 0,11,12,13]);
> print sig_new
> z2 = concatenate(zeros((1,M-(len(sig_new)%M))))
> print z2
> sig_pad = concatenate((sig_new,z2),1);
> print sig_pad
> sig_mat = reshape(sig_pad,(len(sig_pad)/M,M));
> print sig_mat
> sig_tran = transpose(sig_mat);
> print sig_tran
> 
> output_poly=zeros((shape(sig_tran)))
> print "output_poly:",output_poly
> for irow in range(M-1):
>       print "the sig:",sig_tran[irow], "the coef:",h_flip[irow]
>       ytmp=FIR_filter(sig_tran[irow],h_flip[irow])
>       output_poly[irow]=ytmp
> 
> output=sum(output_poly)
> print "output:",output