[time-nuts] ADEV query Timelab and TICC

bg bg at lysator.liu.se
Tue Mar 21 15:37:55 EDT 2017

Look at ICD-GPS-060.
10V into 50ohm, sub 50ns risetime and 20us pulse lenght is specified in figure 3-2.
--     Björn

Sent from my smartphone.
-------- Original message --------From: Hal Murray <hmurray at megapathdsl.net> Date: 21/03/2017  19:18  (GMT+01:00) To: Tom Van Baak <tvb at leapsecond.com>, Discussion of precise time and frequency measurement <time-nuts at febo.com> Cc: hmurray at megapathdsl.net Subject: Re: [time-nuts] ADEV query Timelab and TICC 

tvb at LeapSecond.com said:
> The TAPR dividers tend not to have "this problem" because they output at
> wimpy TTL/CMOS levels.

Modern CMOS drivers have fast rise times.  As long as the rise time is short 
relative to the cable length, it gets doubled if the end of the cable is an 
open circuit.

> Older equipment can have powerful outputs. 10V into 50R is, what, 1/5th of
> an amp? Logarithmically, that puts a 5061A 1PPS closer to an automobile
> starter motor or heart defibrillator compared to modern logic gates. 

There is a big difference across logic families.  Many can drive 50 ohms.

RS-232 drivers are explicitly limited to reduce EMI.

These are my opinions.  I hate spam.

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