[time-nuts] Meinberg or T/Bolt for PC time?

Chris Albertson albertson.chris at gmail.com
Mon Aug 11 22:34:02 EDT 2014


LOTs of suggestions here but  I'd do this first:

1) Define the timing requirements for Ham digital modes.  Are you on HF or
microwave?  what level of accuracy do you need?

2) Read all the documentation on NTP you can.  Start here:
http://www.ntp.org/documentation.html
So many people don't understand how NTP works.  The key things are (1) it
is peer to peer and (2) each peer should have multiple reference clocks.  3
or 5 is a good number.  A reference clock can be a GPS receiver, another
NTP server or a radio or whatever but today in 2014 mostly either another
NTP peer or GPS.






On Mon, Aug 11, 2014 at 2:09 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
> chris at chriswilson.tv said:
>> I have 4 windows based PC's on my home network, for years i have used
>> Meinberg or an equivalent to set the PC time. I was wondering if I
could, or
>> should, use my permanently on Trimble Thunderbolt to set the PC clocks?
Any
>> advantages or disadvantages. I believe there's a way to use Lady Heather
to
>> interface with a PC for setting the time, is that true? Thanks. My main
>> desire for accuracy is amateur radio digital modes.
>
> What sort of accuracy do you want/need?  How good is your current network
> connection?
>
> Is there a good web page describing amateur digital modes and/or the
timing
> accuracy they need?
>
> ----------
>
> albertson.chris at gmail.com said:
>> Pick one of the PCs, the one you are going to leave running 24x7 and
connect
>> that one to theTB using a serial cable.  Yes a real RS232 serial cable.
  It
>> is MUCH better to use a serial port then a serial to USB dingle.     When
>> you guid the serial cable make sure the PPS from the TB is on the DCD
line
>> and get the polarity correct.
>
> The TBolt doesn't come with the PPS on the DB-9 connector.  If you pull
the
> cover off, it's easy to add a jumper from the BNC connector to the unused
DCD
> pin on the DB-9.
>
> That may not work well.  The problem is that the PPS pulse is short.
> Sometimes it works, sometimes it doesn't.  If it works when you test
things,
> it may fade out when you turn around.  Depends on your PC and whatever.
 YMMV
> etc.
>
> You can add a FatPPS from TAPR.
>   https://www.tapr.org/kits_fatpps.html
>
> I kludged in a diode, R and C.  (The R limits the charging current.  It
> discharges through the RS-232 receiver.)  It works.
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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-- 

Chris Albertson
Redondo Beach, California



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