[time-nuts] ARM boards for low-cost GPSDOs

paul swed paulswedb at gmail.com
Thu Apr 10 21:23:18 EDT 2014

Thats what I am saying the compute power is amazing even with arduinos.
I find it crazy to trip over limitations when this technology is available.
So yes I hope to use the STM board to solve the WWVB BPSK issue. At $21 its
a so what for me $ wise at least. I purchased 3 just because they do appear
pretty handy. The same with the launchpads. Now I went out to the TI site
and they have additional launch pad eval kits. All on nice boards just like
the STM evals.

Hope this helps Hal who started the thread.
I have said enough and on to that old Forth code.

On Thu, Apr 10, 2014 at 8:11 PM, Chris Albertson
<albertson.chris at gmail.com>wrote:

> I'm thinking about good reasons to build a GPSDO using something as big and
> powerful as a 32-bit ARM processor.    I think the reason is that you are
> not really building a GPSDO but some other device that just happens to have
> a GPSDO inside of it.
> For example you want to build a laser range finder and you need to measure
> time of flight delay.  You'd need a very good clock and while you are at it
> why not discipline the clock with GPS.      I could think of some radio
> experiments where I would want pairs of receivers with their local
> oscillators running in phase but many miles apart, so I'd build a GPSDO
> into the radio.    The ARM would support running the GPSDO, the bigger
> application and also remote access over the network or Internet.
> Today people mostly will build a stand alone GPSDO in a dedicated box and
> then connect the 10MHZ output to whatever is needed but now as we have
> seen, you can build a GPSDO completely in software, if your project already
> has a computer then you can run a GPSDO inside an interrupt handler as a
> background task.  Adding GPSDO functionality to an existing product is
> almost trivially simple, just $2 in parts and some software if you already
> have a CPU and OCXO as part of your system.
> Placing the GPSDO inside the product means the gpsdo can run at a frequency
> that is more useful and needs no conversion.   So you can have the GPS
> control a 23 Mhz crystal if that is what your laser rangefinder needs.  Now
> that the cost of a GPSDO has fallen to $3 you can build them into
> "everything".  It no longer needs to be a shared device.
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