[time-nuts] Why are 1PPS signals so skinny?

[SAIDJACK at aol.com]

QED: here is a phase noise plot of a 200ms 1PPS pulse showing up in the  
phase noise spectrum of a 10MHz source (at 1Hz to 10Hz offsets) because the  
unit was providing a 100mA current pulses into the cable, and power supply  
modulation of the 10MHz output happened inside the unit.
 
The pulses would likely not be visible if they had been only microseconds  
long, or the cable was not incorrectly end-terminated and causing the 
massive DC  current to flow. Yes, yes, the unit "could have been designed to 
handle that  scenario", but the point is: modulation is going to happen, and 
could be "10's  of Watts", and it will likely have some effect in one way or 
another.
 
The discussion started with the question of why one would design short 1PPS 
 pulses versus long pulses. This is one reason why.
 
 
In a message dated 5/15/2012 14:24:07 Pacific Daylight Time,  
mikes at flatsurface.com writes:

On  5/15/2012 5:14 PM, SAIDJACK at aol.com wrote:
> it is the effect of what  follows after that leading edge, and  propagates
> down the power  supplies to cause side effects that is being discussed  
here.

I'm  asking "What side effects?" I haven't seen any mentioned. And 
really, if  an increase in power draw of 10 watts for an entire lab 
environment causes  any problems, I'd question the quality of the power 
supplies, and ask what  happens when you simply turn on the  light?



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