[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Discuss-gnuradio] Frequency Xlating FIR filter: bug in gr_rotator
From: |
Sérgio Rui Silva |
Subject: |
[Discuss-gnuradio] Frequency Xlating FIR filter: bug in gr_rotator |
Date: |
Thu, 10 Jul 2003 15:39:19 +0100 (WEST) |
User-agent: |
PT Multimedia Webmail program |
I have been using the "GrFreqXlatingFIRfilterSCF" and I notice
that its output slowly increases in amplitude (or diminishes,
depending on the frequency setting). I found that this is due to
the "gr_rotator" class. If the absolute value of the
"gr_rotator"s "phase"
variable is printed during the processing cycle one can see that
its value starts with 1.0, as it should, and then augments
slowly. I think this is because the recursive multiplication
used causes a precision error to increase in one direction. I
solved this by
not using the gr_rotator class but the gr_nco class instead.
This solution is not as elegant as the one with the gr_rotator
class, but it does the trick by now... Any ideas one how to
solve this correclty?
Sérgio Rui Silva
************************************************************
Faculdade de Engenharia da Universidade do Porto, Portugal
http://www.fe.up.pt
*************************************************************
---------------------------------------------------------------------------------------
Words of wisdom:
"Never underestimate the bandwidth of a station wagon full of
tapes hurtling down the highway"
Andrew S. Tanenbaun
-------------------------------------------------------------------------------------
--
SAPO ADSL.PT, apanhe já o comboio da Banda Larga. Kit SAPO ADSL.PT - Grátis
http://adsl.sapo.pt
O SAPO já está livre de vírus com a Panda Software, fique você também!
Clique em: http://antivirus.sapo.pt
GrFreqXlatingFIRfilterSCF.cc
Description: Binary data
GrFreqXlatingFIRfilterSCF.h
Description: Binary data
- [Discuss-gnuradio] Frequency Xlating FIR filter: bug in gr_rotator,
Sérgio Rui Silva <=