Re: sign_extend.v!

GNU Radio
1

-----Original Message-----
From: Josh B. [mailto:[email protected]]
Sent: Sunday, March 13, 2011 10:52 PM
To: [email protected]
Subject: Re: [Discuss-gnuradio] sign_extend.v !!!

Sign extension - Wikipedia

<website that explains what it means to sign extend - this is what this
module does - more detailed explanation as to how it does it appears
below>

On 03/13/2011 07:47 PM, Alaa Salaheldin wrote:

Can anyone please help me to understand what’s going on in sign_extend.v ,
this macro is initiated in the cic_decim.v

sign_extend #(bw,bw+maxbitgain)
ext_input (.in(signal_in),.out(signal_in_ext));

instantiates the sign_extend module. Positional parameter settings
“#(bw, bw + maxbitgain)” will be assigned to bits_in and bits_out,
respectively.

when i opened the macro i couldn’t understand it’s function

// Sign extension “macro”
// bits_out should be greater than bits_in

module sign_extend (in,out);

module with 2 ports: in & out

parameter bits_in=0; // FIXME Quartus insists on a default
parameter bits_out=0;
input [bits_in-1:0] in;

size of input port “in” is determined by “bits_in”

output [bits_out-1:0] out;

size of output port “out” is determined by “bits_out”

assign out = {{(bits_out-bits_in){in[bits_in-1]}},in};

this expression assigns a value to out using both concatenation &
replication

{(bits_out-bits_in){in[bits_in-1]}} replicates in’s MSB (bits_out -
bits_in) times. This value is then prepended (via concatenation) to in.

Voila! Sign extension implemented in verilog and explained in the
webpage Josh pointed to above.

endmodule

Thanks in advance.

Hope this helps,

–Bob

2

I am trying to run this script available at

http://swigerco.com/gnuradio/ate/

to sweep through several frequencies and to log the data. However
running the script gives me an error regarding the “import usrp_siggen”
(I am attaching some of code below, the error is “no module named
usrp_siggen.py”).

What might be done to fix this?

Best regards,
-Vijay

initial portion of the code

import wx
import usrp_siggen
from gnuradio import gr
from gnuradio import usrp
from gnuradio.eng_option import eng_option
from optparse import OptionParser
from gnuradio import eng_notation
import math

ID_ABOUT = wx.NewId()
ID_EXIT = wx.NewId()
ID_STARTFREQ = wx.NewId()
ID_STEPFREQ = wx.NewId

3

On 03/14/2011 02:52 PM, Vijay P. wrote:

I am trying to run this script available at

Automatic Testing - Sweep Generator

to sweep through several frequencies and to log the data. However running the
script gives me an error regarding the “import usrp_siggen” (I am attaching some
of code below, the error is “no module named usrp_siggen.py”).

What might be done to fix this?

I think you need to copy usrp_siggen.py from the gnuradio tree into your
PYTHONPATH or into the working directory of your application.

-JOsh