Simply dividing the 10MHz by a binary counter and taking the most significant bit for the PPS leads to a 161.1391mS pulse.
On Tue, May 15, 2012 at 9:26 PM, Don Latham <d...@montana.com> wrote: > Came to this thread late. Could it be thin because the end output of > even a synchronous dividing chain needs to be resynced to the beginning > to maintain phase? > Don > > > shali...@gmail.com > > The Thunderbolt's output impedance is much less than 10 ohms. However, > > it is only necessary to filter the end of the line for a clean pulse. > > > > See http://www.ko4bb.com/Test_Equipment/CoaxCableMatching.php > > > > I used the Thunderbolt's PPS output as a source in those measurements. > > > > Didier KO4BB > > > > Sent from my BlackBerry Wireless thingy while I do other things... > > > > -----Original Message----- > > From: Said Jackson <saidj...@aol.com> > > Sender: time-nuts-boun...@febo.com > > Date: Mon, 14 May 2012 19:02:51 > > To: Tom Van Baak<t...@leapsecond.com>; Discussion of precise time and > > frequency measurement<time-nuts@febo.com> > > Reply-To: Discussion of precise time and frequency measurement > > <time-nuts@febo.com> > > Cc: Discussion of precise time and frequency > > measurement<time-nuts@febo.com> > > Subject: Re: [time-nuts] Why are 1PPS signals so skinny? > > > > These types of pulses should be routed as open-ended source-terminated > > reflected wave switched transmission lines. Power will only flow for > > nanoseconds as the pulse travels over the line. There won't be a drop of > > 50% of the voltage at the target and no large power spikes in the unit > > or requirements for proper impedance matching at the receiver side. > > > > Some units like the thunderbolt look quite bad driving a 50 ohms > > transmission line, others that are designed with proper 50 ohms series > > impedance create a sharp nice signal. > > > > Bye, > > Said > > > > > > > > > > Sent from my iPad > > > > On May 14, 2012, at 17:21, "Tom Van Baak" <t...@leapsecond.com> wrote: > > > >> Mark, > >> > >> I too once preferred 50% duty cycle 1 Hz signals because they seemed > >> more "natural". But one day during an experiment where I was comparing > >> a large set of clocks I noticed my lab's digital AC power meter was > >> jumping by tens of watts every second. > >> > >> When a dozen DUT generate 1PPS along with as many REF pulses (via > >> cascaded pulse distribution amps) and then these all go to both inputs > >> of a TIC and there's also LED's on both TIC channels as well as the > >> dist amps, the net load is enormous. The last thing you want in a > >> precision timing lab is to load your AC line down exactly once a > >> second. Remember 5V into 50R is 0.1 Amps. That was a modest amount of > >> current in the 1950's, but massive overkill today. > >> > >> So that's why I now prefer short (e.g., 1 ms or 10 us) pulses. > >> > >> /tvb > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > -- > "Neither the voice of authority nor the weight of reason and argument > are as significant as experiment, for thence comes quiet to the mind." > R. Bacon > "If you don't know what it is, don't poke it." > Ghost in the Shell > > > Dr. Don Latham AJ7LL > Six Mile Systems LLP > 17850 Six Mile Road > POB 134 > Huson, MT, 59846 > VOX 406-626-4304 > www.lightningforensics.com > www.sixmilesystems.com > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.