[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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