[time-nuts] Shera revisted

[Michael Wouters]

The Red Pitaya uses a Zynq, and there's an (unofficial) SDR application
available to experiment with.

Cheers
Michael
On Thursday, 11 August 2016, Chris Albertson <albertson.chris at gmail.com>
wrote:

> Thanks for pointing out the Zynq.  Wow you get a dual core ARM and an
> FPGA all in one package.   It seems overkill for a GPSDO but not the
> type you are making as you can transferring the time out of the GPSDO
> using PTP.
>
> The Zyng looks to the the perfect platform for low-cost SDR.
>
> On Wed, Aug 10, 2016 at 2:30 PM, Joakim Langlet
> <joakim.langlet at seaview.se <javascript:;>> wrote:
> > Dear time-nuts,
> >
> > My name is Joakim Langlet (SM0OET) and I just recently joined this list.
> As
> > Brooks Shera was mentioned, I remembered that I was referenced in the
> > footnotes of the original article in the QST - July 1998. It feels almost
> > historical now. Brooks bought a few OCXOs from me.
> >
> > I am currently working on a GPS stabilized OCXO.
> > It is based on a Xilinx Zynq FPGA as the processor and counter
> arrangement.
> > The hardware is starting to take shape. The control voltage of a 20 MHz
> OCXO
> > is set by a DAC coupling from which I hope to set the voltage in very
> small
> > steps.
> > The OCXO has a CMOS level output which is converted to LVDS and is wired
> to
> > the FPGA board. The Xilinx Zynq take a minimum frequency of 19 MHz as
> input
> > to the PLL of the clock tile. My intention is to scale up the clock to
> some
> > where a bit over 200 MHz to be fed to the counters.The 1 PPS from the GPS
> > receiver is also fed into the FPGA to gate the counters.
> >
> > The reason for my choice of processor is that I want to run Linux on it
> in
> > order benefit from the large software base. Time distribution using PTPv2
> > and a nice web-application to visualize and control what is going on
> inside
> > is part of the intended concept.
> >
> > I still have a long way to the finish line but I will try to present some
> > results as I proceed.
> >
> > I am following what is written on this list with great interest. It feels
> > good to know that I am not the only nut ....
> >
> > BR/
> > Joakim
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>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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