<div dir="ltr"><div><div><div><div><div>Hi All --<br><br></div>Larry Gadallah, <span class=""><font color="#888888"><span><font color="#888888">VE6VQ/W7 passed this along. I do read the hpsdr list irregularly and so would have probably seen it in the fullness of time.<br>
<br></font></span></font></span></div><span class=""><font color="#888888"><span><font color="#888888">I personally have no idea what state the DttSP code used in PowerSDR might be, nor have I for a long time. I do know that, despite claims to the contrary, Flex has made changes and additions and failed to make them available, in contravention of the GPL, but I have been too taken up with other issues to pursue any remedy as yet.<br>
<br>The code in DttSP is not completely OS-independent, but it has been compiled and executed on Linux and BSD without change. That was due in large part to testing and debugging by AB2WF, who wrung out the code on OS X.<br>
<br></font></span></font></span></div><span class=""><font color="#888888"><span><font color="#888888">There appears to be no reason for further work on DttSP. I stopped at the point -- for example, in providing facilities for predistortion, in 2008 -- when anybody stopped trying to integrate any new features into an existing application. I was also maintaining a parallel version that didn't use the JACK audio subsystem for signal I/O. As far as I know there had been only one user of that version and so I abandoned it around 2008 as well.<br>
<br></font></span></font></span></div><span class=""><font color="#888888"><span><font color="#888888">All of my subsequent efforts in this area have been in the development of new system whose foundation was distributed processing of multirate signals, with provisions for arbitrary subband extraction and insertion, and time as well as frequency agility -- for example, the ability to "scroll back and forth " a signal in time for a useful period on one or more selected subchannels. Once again, the path that current RF hardware development seems to have been taking makes the implementation of this system needlessly complicated. But perhaps that's a discussion for another time. The development of DttSP was largely a labor of love. That wasn't a mistake but it's not something to repeat.<br>
<br>73<br></font></span></font></span></div><span class=""><font color="#888888"><span><font color="#888888">Frank<br>AB2KT/VE3<br></font></span></font></span><div><div><div><div><div><div><div><div><div><div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Sun, May 11, 2014 at 7:22 PM, Warren C. Pratt <span dir="ltr"><<a href="mailto:warren@wpratt.com" target="_blank">warren@wpratt.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class=""><div class="h5">***** High Performance Software Defined Radio Discussion List *****<br>
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Hi Larry,<br>
<br>
We have generally moved away from DttSP. From your list below, it
looks like the latest version we used in PowerSDR was:<br>
<br>
<font face="courier new, monospace">W5WC/PowerSDR_HPSDR_mRX/Source/DttSP
321d 19h 3049<br>
</font><br>
That sounds about right as I recall. <br>
<br>
As far as I know, Flex still uses DttSP in their version of
PowerSDR. Our openHPSDR evolution was to first re-write parts of
that version and then later, as I mentioned, move on to a newly
developed library, "wdsp".<br>
<br>
With regard to your DttSP questions: I believe that DttSP was
written with the goal of being computer architecture and OS
INdependent. The version in PowerSDR has a fairly substantial
interface piece that is more or less tied to the software
architecture of PowerSDR. The good news is that there's an
interface there and it can be used in other applications; the bad
news is that it limits the flexibility of the underlying library.<br>
<br>
I believe that there must be several users of DttSP out there.
openHPSDR has not made any effort to share fixes and improvements or
participate in a general DttSP repository, at least for quite some
time. All the changes we made are, of course, open source and
available to anyone to use subject to the terms of the GNU GPL v2
license.<br>
<br>
73,<br>
Warren NR0V<br>
<br>
</div>
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