[hpsdr] ISD Theory References?

[Rob Frohne]

Hi,

Pardon my ignorance; I haven't been party to all the discussion going on 
with the ISD, and I'd like to be brought up to speed.  A Google search 
for "Integrating Sampling Detector" reveals only one hit, the Pheonix 
wiki page.  It seems that a number of people here on the list are 
convinced that it is better than a QSD or commutating mixer.  It appears 
that Ahti isn't completely happy with his experimental results.   Phil 
has some simulation results on his blog page, but examining the 
simulation requires Windows and I'm a Linux guy.  Gerald has a 
description of the QSD in his first article: 

http://www.flex-radio.com/articles_files/SDRFMP1.pdf

Referring to Figures 10 and 11 of that article.  Are we replacing the 
leaky integrators (RC low pass filter )with an ideal integrator and 
varying the time it is connected?   I'd like to see a block diagram.  
Ahti's circuit sure looks a lot like the block diagram and simple 
circuit described in Gerald's article (Figure's 10 and 11) to me.  So 
what exactly are the differences between a QSD and an ISD?

What are the theoretical advantages/disadvantages of an ISD over a 
commutating mixer, or a QSD? 

Maybe if I understood all the above, I could make some progress on 
understanding why Ahti's circuit isn't as good as expected, which is 
needed to advance the Pheonix project, and I'm interested in that.  :-)

73 and thanks for bearing with me,

Rob, KL7NA

-- 
Rob Frohne, Ph.D., P.E.
E.F. Cross School of Engineering
Walla Walla College
100 SW 4th Street
College Place, WA 99324
(509) 527-2075			 http://www.wwc.edu/~frohro

-------------- next part --------------
A non-text attachment was scrubbed...
Name: frohro.vcf
Type: text/x-vcard
Size: 318 bytes
Desc: not available
URL: <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/attachments/20060831/d0b167c3/attachment-0003.vcf>