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@megapathdsl.net> Date: 21/03/2017 19:18 (GMT+01:00) To: Tom Van Baak <tvb@leapsecond.com>, Discussion of precise time and frequency measurement <time-nuts@febo.com> Cc: hmurray@megapathdsl.net Subject: Re: [time-nuts] ADEV query Timelab and TICC tvb@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. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.