Setting the time

Tony Anderson tony_anderson at
Wed Aug 29 04:42:58 EDT 2012


The primary need is for the XOs in the school to have the same time (to 
a few seonds, even a minute or so, is probably ok. The primary need is 
to have information from the XOs be somewhat consistent. The school 
server time should also be accurate to a few minutes, of course.

At the moment, it is off by some hours because of problems setting the 
time zone. Some of the XOs are off by a day or two.

Once I get XS-0.7 set up (currently using XS-0.6 (NEXS version), it 
should be easy to set the school server time. Having a gps stick would 
reduce the burden on the school staff to administer although it may be 
possible to get low bandwidth access to the internet via a gsm modem 
(edge) which could allow ntp synchronization.

What I would really like is a method to allow the XOs to synchronize 
with the school server as they connect. This should happen two or three 
days a week when school is in session.



On 08/27/2012 08:28 PM, Hal Murray wrote:
>> In a school deployment, it is desirable that all of the XOs have the  same
>> time. This time should be synchronized with/by the school server  (even if
>> the school server is wrong). It is not reasonable to base this  capability
>> on access to the internet.
> How closely do you need them to be synchronized?  1 second?  1 microsecond?
> 1 minute?
> It should be reasonably easy to setup ntpd on the school server and get the
> XOs to set their clocks when booted.
> You may want/need a cron job to set the time occasionally.
>> Casio sells 'atomic' watches that synchronize to Ft. Collins by radio.
>> Neat, but how does this work in Rwanda?
> WWVB runs at 60 KHz.  There are several similar systems in other countries.
> I don't think any of them make it to Africa.  GPS does.
> You can get USB GPS receivers for under $50.  The SiRF chip is the most
> popular in the low cost units.  It's crappy if you need ms level timing, but
> good enough if all you need is 1 second.

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