Setting the time
tony_anderson at usa.net
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.
More information about the Devel