[time-nuts] Trimble Thunderbolt 1pps

Mike S mikes at flatsurface.com
Mon Jan 27 21:01:18 EST 2014


On 1/27/2014 1:33 PM, Robert Atkinson wrote:
> I looked at this a while ago. The "spec" only defines transmission levels, it does NOT specify receive thresholds.

It certainly does...

"2.1.3 For data interchange circuits, the signal shall be considered in 
the marking condition when the voltage on the interchange circuit, 
measured at the interface point, is more negative than -3 volts with 
respect to Circuit AB (Signal Common). The signal shall be considered in 
the spacing condition when the voltage is more positive than +3 volts 
with respect to Circuit AB (see 6.2). The region between +- 3 volts is 
defined as the transition region. The signal state is undefined when the 
voltage is in this transition region."

- ANSI TIA/EIA-232-F (1997)


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