[time-nuts] An embedded NTP server

Chris Albertson albertson.chris at gmail.com
Wed Dec 26 17:01:24 UTC 2012

The VXCO quality hardly matters for an NTP server.   As long as it
does not gain out loose more then 1 uSecond per second.  In other
words one part per million is fine for NTP.  The goal is not to
produce a 10MHz GDPDO.  Clients using this server over the Ethernet
are happy to keep time ti 1 millisecond.

Most (almost all) NTP servers use a TTL can oscillator.

On Wed, Dec 26, 2012 at 4:41 AM, M. Simon <msimon6808 at yahoo.com> wrote:
> You don't mention the quality of your VCXO. Do you have a part # or else specs i.e. ppm vs temp, time, voltage, etc.
> Nice pic btw. And that looks like an OSH Park "gold plated" board. I love their service.
> Simon
> =======================
> Message: 1
> Date: Tue, 25 Dec 2012 12:18:30 -0500
> From: Michael Tharp <gxti at partiallystapled.com>
> To: Discussion of precise time and frequency measurement
>     <time-nuts at febo.com>
> Subject: [time-nuts] An embedded NTP server
> Message-ID: <50D9DFE6.2050202 at partiallystapled.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> Hello and Merry Christmas,
> I made an embedded (S)NTP server. The software is still under
> development and will eventually include a low-grade GPSDO but right now
> even the simplistic algorithm is working quite well so I figured I'd share.
> http://www.eevblog.com/forum/oshw/%27laureline%27-embedded-gps-ntp-server/
> This is a low-level microcontroller implementation, there is no OS nor
> ntpd in the traditional sense. Just enough logic to keep time using the
> incoming PPS and timestamps, and a tiny VCXO to discipline. It's no
> Thunderbolt and there is no clock output but it should be fantastic at
> NTP. Before too long I will have adapters for connecting to Oncore
> GT+/UT+ (and maybe M12, haven't checked) as well as Trimble Resolution T
> and Resolution SMT using a ribbon cable instead of the jumper wires.
> All open-source hardware and software. Pictures, details, and design
> documents are in the eevblog thread. I'll let you all know if and when
> I'm ready to sell them, for now I just wanted to show what I've got.
> -- m. tharp
> Engineering is the art of making what you want from what you can get at a profit.
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Chris Albertson
Redondo Beach, California

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