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

[Michael Tharp]

On 02/09/2013 08:35 PM, Chris Albertson wrote:
> Features?
> 1) Power the thing with "power over Ethernet" then you can remove the
> coaxial power input.  Also this would make it real easy to place the
> server right at the antenna location.   You would simply run cat-5 up
> to the roof.  The mount the antenna on top of a water proof box with
> the server inside the box.  If power has to come in via the coaxel
> power connection to a wall-wort then it wil be hard to mount this
> server outdoors, near the antenna.

PoE is a great idea, but I think this is better served by using a 
separate, off-the-shelf splitter. It's hard to compete with economies of 
scale. "Real" 802.3af in particular is difficult because of the required 
isolation.

> 2) You really should make provision for a 5V antenna.  All it will
> cost is a tiny little 78L05 to provide a few milliamps.  Put a jumper
> on the board to select the antenna voltage.

You're right, and I've been in "digital mode" long enough that I hadn't 
even considered using a linear regulator for that function. Depending on 
the antenna and input voltage the regulator could end up dissipating up 
to a watt but that's quite feasible. That will definitely be in the next 
revision, then.

> With the GPS on the server using power over Ethernet makes even more
> sense because peoplewill want to place the seaver very near the
> antenna to make the wiring simpler.  Wha not go all the way and put a
> patch antenna on the board?

Again, this sort of comes down to not being able to serve everyone with 
one board. Maybe I can make a "rooftop package" with a patch antenna and 
passive power injector/splitter in the box. It looks like most ceramic 
patch antennas already have a u.FL (they call it "IPEX") connector which 
is what I was already planning on using internally.

Thanks a bunch for your feedback.
-- m. tharp