Does anyone know how the accuracy of a radio controlled clock is proved.? The one we got boasts it's accuracy to be within a second in a million years.
My "Atomic Clock" consists of a conventional quartz crystal clock which is updated daily by receiving widely available Bureau of Standards time broadcasts. It is typically accurate to within 1 second although it was off by about a full minute the day that time changed from daylight saving to standard time. I compare it against actual radio broadcast reception of a WWV station.