<html><body style="font-family: 'Helvetica Neue',Helvetica,Arial,sans-serif; font-size: 12px;"> A free (to download) book which is a good guide to theory is at :<br /><br />http://dspguide.com/<br /><br /><blockquote>Richard <br /><br /><br />----- Original Message -----<br /><div style="width:100%;background:rgb(228,228,228);"><div style="font-weight:bold;">From:</div> "Alberto I2PHD" <i2phd@weaksignals.com></div><br /><div style="font-weight:bold;">To:</div><hpsdr@lists.openhpsdr.org><br /><div style="font-weight:bold;">Cc:</div><br /><div style="font-weight:bold;">Sent:</div>Sat, 10 Aug 2013 23:29:46 +0200<br /><div style="font-weight:bold;">Subject:</div>Re: [hpsdr] Help with DSP please<br /><br /><br /><div class="moz-cite-prefix">On 8/10/2013 9:24 PM, Bob Cowdery
wrote:<br /><br /></div>
<blockquote>
<ol><li>
<i>Is there a write up at a block level of SharpDSP because
I'm not sure why blocks are ordered as they are. The purpose
of most is obvious but I'm a bit confused by the oscillator
block which I guess is converting to baseband(?). </i><i><br /></i> </li>
</ol><i> </i>
<i>Demodulation is something I don't fully get. I believe
the convolution directly demodulates CW/SSB (and from what I
remember can convert to baseband as well) but for other
modes demod is tacked on the end of the processing.</i>
<i> </i>
<i>When doing the overlap/add method of fast convolution I
don't know how one calculates how big the FFT should be or
how many taps the filter should have in relation to the
sample block size and what the effect of the choice is.
Should a small block size (for reduced latency) have a
smaller FFT? I've not found a really good algorithm that
explains this and many I found seem to differ in approach so
I'm not clear on the correct implementation.</i>
<i> </i>
<i> </i>
<p><i>Any pointers appreciated.</i></p>
</blockquote>
<br />
Bob,<br /><br />
a detailed answer would take many pages and hours to write it
down.<br />
What I can warmly suggest you is this really excellent book, where
all of your questions above <br />
are answered in a clear and tutorial way :<br /><br /><a class="moz-txt-link-freetext" href="http://www.amazon.com/Understanding-Digital-Signal-Processing-Edition/dp/0137027419">http://www.amazon.com/Understanding-Digital-Signal-Processing-Edition/dp/0137027419</a><br /><br />
I have it and I am very glad that a friend a few years ago pointed
me to it.<br /><br /><br /><div class="moz-signature">-- <br /><i><b>73 Alberto I2PHD</b></i>
</div>
</blockquote></body></html>