[time-nuts] Trimble Thunderbolt 1pps

Hal Murray hmurray at megapathdsl.net
Fri Jan 3 18:26:57 EST 2014


albertson.chris at gmail.com said:
> The "line driver" was a TTL inverter chip  I was going through about 50 or
> 60 feet of cat-5 wire. TTL level serial is always marginal, the specs say it
> should not work but it does work most of the time.

Modern CMOS chips work much better than real TTL.  Some CMOS chips have weak 
drivers.

Cat-5 should be fine for 100 ft.

Here are scope pictures from the PPS signal from a TBolt driving 100 feet of 
various types of wire:
  http://www.megapathdsl.net/~hmurray/time-nuts/coax/Coax-20ns.png
  http://www.megapathdsl.net/~hmurray/time-nuts/coax/TP-20ns.png
The clump on the left of each graph is the input.  The stuff on the right is 
the output.  The scatter is due to the different prop times.



-- 
These are my opinions.  I hate spam.





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