[time-nuts] Trimble Thunderbolt 1pps

[Robert Atkinson]

Hi,
I'd  already admitted my miss on that one in an earlier reply (don't know how i missed it but it was not a controlled copy of the spec ;-) .
That not withstanding, show me a readily available receiver chip that actually meets that requirement. Most equipment that I've seen that would not work with 5V logic levels was failing to respond to the positive input level not the lack of a negative level. Ofteh this appeared to be caused by external circuitry, most likely intended for EMI/ESD/surge protection.
 

________________________________
 From: Mike S <mikes at flatsurface.com>
To: time-nuts at febo.com 
Sent: Tuesday, 28 January 2014, 2:01
Subject: Re: [time-nuts] Trimble Thunderbolt 1pps
  

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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