[time-nuts] Shera revisted
kb8tq at n1k.org
Thu Aug 11 07:06:42 EDT 2016
To your earlier point, there are a number of fairly low cost boards with Zynq’s on them.
They aren’t into the $5 range, but they are not that much more than one of the Beagle
> On Aug 10, 2016, at 11:18 PM, 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> 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
>> 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 ....
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> Chris Albertson
> Redondo Beach, California
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