[time-nuts] Re: Network interface cards that support timestamping

[Lux, Jim]

On 2/1/23 4:15 PM, Bob Camp via time-nuts wrote:
> Hi
>
> A 10 or 100 microsecond wide 1 pps signal is more common than a 10 to 100 millisecond
> wide pulse.
>
> Why?
>
> Back in the day, they coupled this stuff via a transformer. The frequency response issues
> made a narrower pulse more appealing. These days it is not uncommon to try to drive a
> 50 ohm load to some sort of logic level. The less time you have to do that, the happier
> your driver IC (and regulator) are likely to be.
>
> One example of this would be the Trimble TBolt. It has a 10 us wide output pulse. Another
> would be a uBlox LEA-6T (and the others in that lineup) with a default 10us wide output.
> 	
>
> Bob


Power dissipation, too. Fewer joules in a 10 microsecond pulse than in a 
10 millisecond pulse.