[time-nuts] Embedded NTP server ideas and feature requests

[Michael Tharp]

Greetings time-nuts,

I've finally gotten the software for my NTP server project to the point 
where I'm comfortable shipping the boards I have now, so it's about time 
to spin the next revision. If you could take a minute to look over the 
feature list and let me know on- or off-list what you'd like to see, 
hardware or software, I'd really appreciate it.

Here's the current product. I have 3 built and tested, so if you like 
what you see and you have a GPS to hook it up to I'd be happy to send 
one your way.

https://www.tindie.com/shops/gxti/laureline-gps-ntp-server/
http://partiallystapled.com/2013/01/laureline-gps-ntp-server/

There are a few things that I will definitely be changing. For one, 
instead of a "bring your own GPS" I will be integrating a u-blox NEO-6M 
receiver. It's not a timing receiver, but from what I've been able to 
find on this list it is quite suitable for NTP. Should add about $10 to 
the cost but compared to a $30 used Resolution T or similar that's a 
good tradeoff. There will be a header where you can connect your own 
favorite receiver. Alternately, the NEO-6T timing receiver uses the same 
footprint and be soldered down instead, but is much harder to source.

The 5V antenna power will also be removed so there is one less power 
supply to deal with, but if you have an antenna that requires more than 
3.3V then you can use a header to supply any voltage that it might need. 
I will also be beefing up supply filtering. It performs well now but I 
want to make absolutely sure that EMI is a non-issue.

I've heard some people say they'd like a 10MHz output from the server. I 
can break out the (digital) 10MHz clock from the VCXO, and/or provide a 
way to connect your own OCXO if people are interested. The latter will 
require some kind of adapter though as most OCXOs need more than the 
3.3V VFC used here - a simple op-amp gain will work fine - and a limiter 
might also be needed to digitize the sine-wave coming in from the OCXO. 
These can be dealt with separately, though.Simply adding an ovenized 
oscillator and timing GPS one can turn Laureline into a pretty good GPSDO.

On a semi-related note, I have two PPS Piggies in stock in my Tindie 
store as well, so anyone with a Trimble Resolution T or SMT who needs a 
way to hook them up should take a look.

Happy ticking,
-- m. tharp