[time-nuts] Trimble Thunderbolt 1pps

[SAIDJACK at aol.com]

Hi Hal,
 
still pretty impressive results, thanks for sharing the data.
 
bye,
Said
 
 
In a message dated 1/3/2014 17:10:13 Pacific Standard Time,  
hmurray at megapathdsl.net writes:


saidjack at aol.com said:
> Your plots don't show the wave  being reflected by the cable end, and
> bouncing back and forth.. Until  settling down. 

Yes.  I'll put up some nasty pictures if anybody  wants an ugly example.

For that set of graphs, I tried to get rid of  that sort of junk.  I was 
working on the bench, using connectors and  clipleads rather than PCBs or 
soldering whatever so things could be  (much?) cleaner.

For the coax, there was a short chunk of coax from the  TBolt to a Tee at 
the 
scope, then the long chunk of coax under test, then  a 50 ohm terminator at 
the other scope input.  You can see some  ringing due to the coax not 
really 
matching the terminator.

For the  twisted pairs, I used clipleads.  The first/simple try wasn't good 
 
enough.  The non-twisted cliplead wires were long enough to cause  visible 
cruft.  I ended up with a BNC to cliplead adapter with wires  that were 
only 6 
inches long.

At the far end, I had a resistor  merged into the clipleads, and adjusted 
it 
for best results.

For  the Cat-5 and Cat-6, I used a pair of RJ-45 to DB-9 adapters without 
the  
DB-9 connector.  The wires coming out of the adapers are about 2  inches 
long.

I forget what I did for the RG-6 which is 75 ohms.  I  have a pair of 50-75 
adapters, but I don't remember doing any scaling to  get the graphs to come 
out right and I don't see anything in the gnuplot  commands to make the 
graphs.  So I probably use a cliplead setup like  for the twisted pairs.


-- 
These are my opinions.  I hate  spam.



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