[time-nuts] TBolt: UTC PPS

Neville Michie namichie at gmail.com
Mon Mar 29 22:31:51 UTC 2010


The most available analogue dial for PPS clocks is the common quartz  
clock movement.
You can leave the unpowered quartz unit in circuit and just connect  
to the coil.
The drive is a 5V square wave signal of 0.5 Hz coupled through an  
electrolytic capacitor
in the order of 10 - 100mfd. A series resistor of a few hundred ohms  
may help.
Each make of clock may need different values to work best, the drive  
is the alternating
positive and negative impulse. The original unit may have had a pulse  
about 20ms long,
but the square wave drive gives a longer tail. Over-driving is just  
as bad as under-driving,
to work well you must optimise the capacitor and resistor.
It is simple to divide the PPS to the square wave, but what is needed  
is a simple/surefire
method of adding/removing the leap seconds. Preferably one that works  
automatically.
Any ideas?

Neville Michie


On 30/03/2010, at 9:02 AM, Hal Murray wrote:

>
> tvb at LeapSecond.com said:
>> The words "insert a pulse" is what causes the confusion in  
>> conjunction with
>> leap seconds. There is no extra or missing pulse; no double pulse,  
>> no early
>> or delayed pulse.
>
>> The 1PPS output continues to give a pulse at a 1 Hz rate  
>> regardless if there
>> is leap second or not. There is never any ambiguity with TAI or  
>> UTC with
>> respect to the pulses themselves.
>
> Right.
>
> I was commenting about the sub-thread that was expecting an extra  
> pulse so a
> mechanical clock would stay in sync over a leap second event.
>
> Since what's needed is removing a pulse (to allow for the leap  
> second),
> rather than inserting a pulse, I still like the idea of poking a  
> finger on
> the right place in the clock to gum up the works for one tick.
>
>
> -- 
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
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