Hi Tom, The part that I am confused on is how the DCD pin is being accessed and time stamped. Where would I find software for that purpose ?
Perhaps some of the others can straighten me out ? Especially if there is software that will run on an old Win 98 laptop. Bill....WB6BNQ Tom Van Baak wrote: > > OK, I wasn't paying attention as the info passed by. 'Xactly how is this > > huge signal introduced to the PC? I remember something about a voltage > > divider off the hot side of the line, put on an input pin of the PC's > > com port and then somehow timestamped and put on a data file. Howsat > > done again? Sorry to be so lame, but I really wasn't paying attention. > > Don > > Hi Don, > > What I did in the quick PC experiment was feed the output of a > 5 VAC wall-wart transformer through 1k to DCD (pin1) of the > PC's serial port. Probably not wise to voltage divide raw mains > power and send it to a serial port. If using a high-z input of a > microcontroller, the doc2508.pdf app note that you found shows > both sides of mains going through 1M resistors. > > There was concern that noise would cause false triggering. There > are a variety of hardware-only or software-only solutions to this > concern. Bill found a robust ZCD circuit if you need a hardware > solution. Time-stamping samples is the basis of software solutions. > > Note looking for a sample 990 to 1010 milliseconds from the last > sample is a nice way get 1PPS from 60 Hz. This is more immune > to noise than traditional division-by-60 techniques. > > As it turns out, I've gotten clean 1PPS data with no h/w or s/w > filtering so maybe this whole noise concern is overblown. > > /tvb > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
