Tuesday 29 October 2013

Beacon Clocks & Chocolate Teapots

Well - the "Real-Time" clock isn't nearly so accurate as one might hope...


It has been gaining 8 seconds per 24 hours - exactly the same order of error as I was experiencing with the Arduino timing itself (on its internal clock) BEFORE ANY CLOCK TRIMMING.

As trimming the RTC module (e.g. by deliberately throwing away a second every three hours) would only help when the beacon system actually is running, I've decided to abandon the whole "Real-Time" Clock idea...

Despite these timing challenges, the beacon has been performing well (as I've forced a clock re-sync every 8-12 hours). Here's the WSPR performance over the past 24 hours on 30m...


For the moment I've gone back to my original "Occam's Beacon" code, which derived timing from Arduino's "millis()" function. 

For the longer term, I've ordered a GPS module - Hans g0upl lists them at an attractive price.

"Time gentlemen please" de m0xpd

1 comment:

  1. With a GPS module you could also get the grid square for WSPR from the satellite...

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