Trying again - SDR hardware and software

Fri Oct 10 16:39:07 CDT 2008

Thanks for the very informative post.

I am very interested, but short on time.  However, I could stand a  
little more development experience under Linux than the occasional  
make/make install and vi, to put under my consulting belt if nothing  
else.  I use Netbeans for Java ME work, and have an OpenMoko phone and  
three Sharp Zaurii on the shelf waiting for me to get with the  
program.  I need to spend some more time on Eclipse.

Maybe I should start by setting up a development toolchain.  I will  
probably install Linux as a vmware appliance on my Windows laptop  
rather than a dual-boot arrangement.  What Linux distro are you  
using?  Which of the three IDEs would you suggest I focus on?

Sean AI4ID

On Oct 10, 2008, at 5:16 PM, WB4JFI wrote:

> Try again, from WB4JFI instead of tfox...
>
> Hey guys.  Are we doin' anything as a group?  The election season is  
> almost
> over, it's time to be thinking about what to talk about at physical  
> Tacos
> and this forum besides politics, ancient radios, and the latest  
> humorous
> finding on the Internet.  How about new radios?
>
> I see that the HPSDR group is about to build the Mercury boards for  
> sale.
> This is a 0-65MHz direct-sampling SDR board that plugs into the  
> HPSDR Atlas
> bus, and uses Ozy for USB communications to the host computer.  It  
> is meant
> to be the receiving companion to the Penelope direct-sampling  
> exciter board.
> The cost for Mercury will be about $330 or so, through TAPR.  Sort  
> of like
> Phil Covington's QS-1R.  The QS-1R looks very good, btw, but the  
> cost is a
> little steep for me right now.
>
> My personal opinion is that while the QSD/QSE-based radios (SoftRocks,
> Brainerd, Flex products) are good, the direct-sampling devices will
> represent a true leap in technology.  They virtually eliminate the  
> image and
> LO radiation (leakage) of most or all QSD/QSE designs.  Even the  
> recent Flex
> radios, which I believe are still QSD/QSE.  Note that even the latest
> versions of PowerSDR does not do receive I/Q balance at multiple  
> points on
> every band.  The same with transmit.  Can you assure that your  
> transmitted
> RF meets the FCC requiements all across the band with only a single IQ
> sample/balance point?  Both the QSD/QSE hardware and the sound card  
> response
> contribute to this imbalance issue.
>
> With 16-bit 130MHz (or higher) RF A/D converters, the hardware can  
> deliver
> at least 14-bits of accurate samples.  Then, processing gain due to  
> digital
> down-sampling can provide more bits.  Yes, there are occasions where  
> the
> dynamic range is still not quite good enough, but those conditions are
> getting few and far between.  the IQ balancing is not an issue,  
> because this
> process is done via firmware inside the FPGA on digital numbers.  No
> real-world analog components to be out of balance at different  
> frequencies.
>
> Also, Mel and I are playing with SDR software under Linux (and maybe
> Windows).  We are learning to use the QT GUI software, along with a  
> couple
> of IDEs.  QT is supposed to work on both Linux and Windows, so the  
> same
> basic code would be usable on both platforms.  Reality is that while  
> QT will
> build the same GUI on both platforms, some of the IO will need to be
> different, due to the different approaches Windows (portaudio) and  
> Linux
> (jack) takes.  We are using the no-cost, open-source version of QT,  
> which is
> full-blown but does not include company support.  See  
> www.Trolltech.com
>
> Eclipse (www.eclipse.org) is an IDE that can have QT integrated into  
> it, and
> is also available for both Linux and Windows.  However, we have  
> found some
> inconsistencies with the most recent combination of QT/Eclipse  
> integration
> platforms.
>
> While waiting for these inconsistencies to be sorted out, I have  
> started
> playing with QT on Linux, with a couple of other IDEs:  Monkey  
> Studio and
> EDYUK.  Both of these are available at no cost from www.qt-apps.org,  
> under
> the development section.  Both requiring compilation - via QT  
> ironically.
>
> It is important to note that when using the IDEs mentioned above,  
> they all
> use the same project source code tree, and do NOT require additional  
> special
> files.  So, a project can actually be built with any of the three,  
> then
> another used to work on it, depending on the programmer's whim.  All  
> three
> also have full source code.  I have not tried Monkey Studio or EDYUK  
> under
> Windows yet, so I cannot guarantee they are cross-platform.  But, QT  
> and
> Eclipse behave identically on Linux or Windows.
>
> Someone here in Charleston is also designing a smaller/less expensive
> direct-sampling RF A/D board that plugs into the Digilent Nexys-2  
> FPGA demo
> board.  He has it undersampling 2 meter activity and displaying the RF
> spectrum in a window, and is working on demodulating the signals  
> now.  This
> is a neat board, not cutting-edge regarding performance (12-bit A/D I
> think), but a great way to learn FPGA SDR software.
>
> Is anybody else in AMRAD-land interested in working on SDR  
> software?  Care
> to join us?
>
> Terry
>
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Sean Sheedy
sean at theSheedys.com
home: 703-777-9009
work: 703-898-0201

39392 Crooked Bridge Lane
Leesburg, VA 20175

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