On 1/8/2012 5:19 PM, unruh wrote:
On 2012-01-08, Chris Albertson<[email protected]> wrote:
I have a UT+ It does 5V logic level pulses but I connect the TTL
level PPS to a MAX232 chip which converts the levels to +/- 8 volts
I think the problem is my long cable.
...
Make sure you properly terminate the cable with 100 ohms. Otherwise you
will get reflections back and forth along the cable, and the cable will
slowly fill with charge, broadening the pulse by a huge amount. It may
also be that the signal is decreasing due to resistance in the line.
The proper termination for EIA-232 is 3000-7000 ohms.
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