[time-nuts] Low cost GPS module for < 100ns timestamping error

Jim Lux jimlux at earthlink.net
Sun May 4 19:08:12 UTC 2014

On 5/4/14, 11:44 AM, Bob Camp wrote:
> Hi
> Well I do have those Sparc machines sitting over in the shed ….. I
> suspect hauling over the CRT monitor to go with it would be a bit of
> a pain. I doubt I would win the “low power GPSDO of the year” award
> with it.
> ————
> Like it or not, once you get to 64 bit math, the “this versus that”
> hardware questions matter less and less on a GPSDO. The world is
> awash in CPU’s that will do what you need to do. The real issue is
> software / firmware. Since GPSDO’s were not a real big deal back in
> the 70’s and early 80’, there probably isn’t a lot of native GPSDO
> code for PDP-11’s or SPARC’s.

One thing I've learned over the last few years is that while they're all 
called SPARC, and have similar instruction sets and architectures, 
they're not that identical.  For the most part, as  you say, you don't 
care: you're writing in C or C++, and it's 32 bit math, so it's almost 
processor independent.

In any case, there *is* native GPS receiver code for SPARCs, but it's 
not from the 70s and 80s. It's from this year and last.  And it's 
probably not releasable in general. But at least it's an existence proof 
that it can be done.

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