Decimation scheme

GNU Radio
1

Hi

Can anyone please help me with some information on the CIC filters in
the USRP? I need to know how many CIC stages there are, what the
cutoff frequency and out of band rejection is and how the decimation
is performed after filtering. Which .v files should I have a look at?

Thank you very much.

Sebastiaan H.

2

On Wed, Jul 16, 2008 at 2:46 PM, Sebastiaan H. [email protected]
wrote:

Hi

Can anyone please help me with some information on the CIC filters in
the USRP? I need to know how many CIC stages there are, what the
cutoff frequency and out of band rejection is and how the decimation
is performed after filtering. Which .v files should I have a look at?

The decimating CIC filter implementation can be found here:

http://gnuradio.org/trac/browser/gnuradio/trunk/usrp/fpga/sdr_lib/cic_decim.v

It’s a 4-stage CIC filter. Decimation is somewhat inherent within the
process, so I don’t understand that question. Sorry.

Good luck.

Brian

3

Hi,

See :
http://gnuradio.org/trac/wiki/UsrpFAQ/DDC

Regards,

Firas

4

Sebastian:

http://users.snip.net/~donadio/cic.pdf

contains more than you ever wanted to know about CIC filters in great
detail
including how to calculate the transfer function.

Bob

ARRL SDR Working Group Chair
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
“Trample the slow … Hurdle the dead”