[time-nuts] inexpensive, black box, GPS or NTP based TTL time capture?

Hal Murray hmurray at megapathdsl.net
Wed Oct 18 14:20:39 EDT 2017


The "no Linux" complicates things.  Ignoring that...

Assuming you have a PC with good time, you can use the PPS capture technology 
to get a time stamp from any signal.  I use it to monitor power line 
frequency with a simple python script.

If you want GPS on that PC, that will use the first serial port.  You will 
need another serial port for each signal you want to monitor.  If ms accuracy 
is good enough, you can use a USB serial port.


You could use a Raspberry Pi instead of a PC.  Some assembly required.

A serial port is electrically rugged.  The IO pins on a Pi are delicate.

The GPS HAT from Adafruit has a small prototyping area.  It should be 
reasonable to add a level shifter and lightning protection.  Again, if ms is 
good enough you can use a USB serial adapter.

Some Pi setups occasionally trash their "disk".  Sometimes they run for 
months.  I think the usual problem is poor power.  If the Pi is doing nothing 
else, you can make a backup copy of the SD card and put things back together 
by following a simple recipe.

------

You also said no IRIG.  In case it helps, you can get IRIG out of a PC.



-- 
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