Dear Rud,
For your FFT, do you use a precompiled library or a source code from a
book? I'm looking for a FFT for a 64 sample complex block. If you have
any C or C++ source code that I could adapt, could you please send it
to me?
Thanks,
Frank
Message: 5
Date: Thu, 26 Jan 2006 22:37:43 -0600
From: "Rud Merriam" <[EMAIL PROTECTED]>
Subject: RF Digital Protocol Education
I want to experiment with digital protocols in ham radio by starting
with the PC soundcard. I understand some of the basics like filters
and FFT. I even have some of them working in code (C++).
I do not know how to proceed from the basics into demodulating an
audio signal into bits.
For instance, I am playing with the VHF packet protocol which use 1200
and 2200 hz signalling. I enter the samples for a single 1200 hz cycle
into the FFT array. The FFT shows a peak at around 1000 hz. The FFT
array is 2048 samples long filled with 0s except for the 1 cycle of
1200 hz which is 40 samples at the rate of 48000 samples per second.
If I put 4 cycles in the FFT array I get 1195 hz which is correct.
Hanning or Hamming Windows do not help.
I have looked at some of the available source but am missing the
insight I need for proceeding further. Any suggestions on how to
proceed further? Any suggestions on books or web sites that address
communications DSP at this level? How about an email reflector where I
can ask questions of DSP gurus?
-73-
Rud K5RUD
ARES AEC
Montgomery County, TX
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/soft_radio/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
