>> See ADEV of a Hamilton M21 Ship's Chronometer: >> >> http://www.leapsecond.com/pages/m21/ > > I'm curious -- how did you pull the data? > > My first guess would be a microphone to pick up the ticks, followed by a > little dsp... > > John
I mostly use Bryan Mumford's "MicroSet timer" which you can read about in his excellent web site: http://www.bmumford.com/microset.html http://www.bmumford.com/mset/modelwatchpro.html For the M21 run I used one of his clip-on acoustic sensors (just a piezo element, I think). But see all the sensors at: http://www.bmumford.com/mset/access/access.html The cute little MicroSet collects data and outputs RS232 (nice) which can then be logged on a PC and processed the same you you'd handle any other clock data. In some cases I pull a "tick" right off the op-amp inside the microset and then use a GPSDO-triggered 53132A to collect data. This gives better resolution and long-term accuracy to the collected data. It works well with analog (stepper-motor) watches because they then act like a 1PPS source. That's how I measured the performance of a WWVB radio controlled watch: http://www.leapsecond.com/pages/Junghans/ This is a great example of "sawtooth" that you probably haven't seen before. /tvb _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
