Worried about time?

WA2ZKDWA2ZKD
in KiwiSDR Discussion
The latency of the KiwiSDR scheme may thwart synchronicity a bit but you may have other needs for precise time. I do various radio related things that require accurate time and was left hanging one day when the Internet went away and all my RPi, BB etc. were left to drift. To fix that I took an older/slower RaspberryPi I had and added the Adafruit 66 GPS module. I was able to get that to provide clock to the ntpd on the RPi and by using pps, I have a local clock accurate to within 10 uSec.  I now point all my computers to that RPi for their time. If the GPS scheme fails, normal network time, which is usually available, takes over. 

Comments

  • jksjks
    edited April 2017
    [humor, sarcasm]

    Sure, but be careful. For some people this is a slippery slope into full-blown "time nuttery", e.g. Time-Nuts, LeapSecond.com. Believe me, I know. It starts with PPS-producing GPS modules. But then quickly escalates into buying a GPSDO and/or surplus rubidium OCXODO from that Ebay guy in China. All of a sudden you're building your own GPSDO. Then acquiring an old hp 5370A/B TI counter, or two, or three or ten. Perhaps even adding my CPU upgrade. Then you score your first cesium standard off Ebay. You might even get one with a semi-working beam tube. Pretty soon the Allen deviation/variation plots are flowing and three-corner hat comparisons being made. This list is maybe 2% of what's likely to happen.

    Now things really fall apart. You decide you need a hydrogen maser. So the sports car and/or summer home get sold to raise the cash required..

    Absolutely no cure, except to get distracted by something equally interesting/addictive.


    WA2ZKD
  • WA2ZKDWA2ZKD
    edited April 2017
    I stopped when I got to short-term repeatably of < 3 uS. That's enough to discern between a groundwave signal and a skywave one when each end  has that precision. I used that technique on my "day job"

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