[hpsdr] Mercury sampling rate

[Philip Covington]

On Sun, Apr 13, 2008 at 8:28 PM, Lyle Johnson <kk7p at wavecable.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>  Hello Chuck!
>
>
>  > "Sorry your question did not get answered. At present the only software that
>  > supports HPSDR is PowerSDR. Hence all the features of that software are
>  > available in terms of sample rates, recording of data and archival. PowerSDR
>  > will allow you to record either I and Q data at up to 192kHz or the
>  > demodulated audio output.  Recording of I and Q at 192kHz allows you to
>  > replay the original recording and tune over the entire 192kHz looking for
>  > signals."
>  >
>  > That's not good news to those of us that were counting on the ability to
>  > capture all or most of a band. Nor does it match up with other platforms
>  > like Perseus (currently records 800 kHz), QS1R (recording not implemented
>  > yet but transfers 1 to 2 MHz worth of samples to the PC), or the SDR-IQ
>  > which records 190 kHz of spectrum.
>  >
>  > I do think it will be important for Mercury to improve the recording
>  > performance...
>
>  Please note that the QS1R software (SDRII Max) is open source, and
>  should be able to be modified in such a way as to support Mercury. In
>  fact, it should be fairly easy to do, since the heart of Mercury was
>  conceived by, and development has occurred with lots of exchanges with,
>  Phil, N8VB.  Same ADC, same capability in the FPGA, same USB interface
>  processor...  It's easy for me to say this, of course, since I don't
>  touch PC-based software :-)

There is a fundamental difference here.   Unless you dedicate some of
the ATLAS bus to a parallel interface to OZY, transferring more than
about 250 ksps serially over the ATLAS will be a challenge.   This
isn't a problem for use with PowerSDR or most Ham radio applications
since 250 kbps in enough.  For those wanting to record wide bandwidths
to disk it will be a problem.   I have not looked to see how many
lines are left on ATLAS, but if you could get enough for an 8 bit or
16 bit parallel bus between Mercury and OZY via ATLAS, the wide
bandwidths then should be possible.   I think that a lot of the ATLAS
bus is already dedicated to other functions so this might not be
possible.  Maybe using LVDS and the 622 mbps serial out of the FPGA
over ATLAS?

Phil N8VB

 1208139723.0