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

Gary E. Miller gem at rellim.com
Wed Oct 18 16:11:16 EDT 2017


Yo Hal!

On Wed, 18 Oct 2017 12:26:27 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> > For under a $100 you could get a Raspberry Pi, a GPS HAT, and
> > connect your input to a GPIO pin.  Configure ntpd to log the real
> > PPS and the input as another 'PPS'.   
> 
> Is there an option to log all individual PPS events?

    # ppswatch /dev/pps0
    trying PPS source "/dev/pps0"
    found PPS source "/dev/pps0"
    timestamp: 1508356708, sequence: 591837, offset:  1412510
    timestamp: 1508356709, sequence: 591838, offset:  1381010
    timestamp: 1508356709, sequence: 591838, offset:  1381010
    timestamp: 1508356710, sequence: 591839, offset:  1397496
    timestamp: 1508356710, sequence: 591839, offset:  1397496

Just redirect to a log file.

> The $100 for a Pi might be significantly low.  It depends on what you
> have in your toy box.

Looking at Amazon, quantity one, I see:

    RasPi3 $35
    GPS Hat w/ remote antenna and cord: $30
    16BG miscro sd card: $9
    RaspI + HAT case: $10
    USB charger: $8
    USB charge cable: $2
    Cat5 ethernet cable: $2

Looks like $96 to me.  You can save some if you buy in bulk,

Plus labor, which after the first one is small.

> For getting started, you also need:
>   SD card reader/writer
>   keyboard and mouse (Pi has USB)
>   display adapter (Pi is HDMI)
>   display

Yeah, just for setup.  Shall we include the price of the desk it sits
and the building it is in?



RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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