Justin, I might think quite a few time Nuts have these. So making progress have build a gps sat message decoder for the GPRMC sentence that gives time and data. I believe most GPS units put that sentence out. Have it decoding time and next is date. Maybe tonight. Then I have to glue this code into the simulator to set the clock. Next will be a update subroutine which is quite tricky as to how the updates done.
Lastly the dates a pain. Always has been. Its the number of days from new years. But it seems that the system doesn't actually care what those digits are. Soooo I am thinking of using the LSD 2 as the day of the month and the single 3rd digit as a hex month. I know cheeky. I can calculate days as the system originally used. Maybe you can't use the 3rd digit for Hex months. But I do know the other digits support hex numbers. So thats were I am at. Lastly I may use a seperate SX28ac as a 20 mc to 100hz divider would save about 8 external divider chips. Just not sure I can make it accurate enough to appease the dc468 gods. Regards Paul WB8TSL On Mon, Dec 6, 2010 at 3:44 PM, Justin Pinnix <[email protected]>wrote: > Paul, > > That is very much appreciated. I have one of these boxes. I didn't > realize > that the signal was no longer being broadcast, so at this point I'm all for > whatever hacks will make it useful. > > Thanks, > -JP > > On Fri, Dec 3, 2010 at 5:55 PM, paul swed <[email protected]> wrote: > > > Well I think this puts me in the dangerous zone of time nuttery. > > > > I had posted to the group about a month ago about a Austron 2201 gps rcvr > > and any documents anyone might have. Russell responded and sent me some > > great documents on the Austron. > > > > In a phone conversation with Russell we started talking about the old > > Truetime dc 468s. Kind of got me thinking. I have been able to design a > > small single chip goes timecode simulator to drive these older clocks. > > > > The dc 468 was always quite attractive with their panelplex 7 segment > > displays. Have re-purposed the boxes for several other projects on > occasion > > using the supply nd the displays. > > > > I find the dc 468s at flea markets still for $5 in the northeast US. > > Generally no converter assembly though it doesn't matter since the GOES > > timecode signals been gone since 2005. > > > > At the moment the software fits in a small parrallax SXB micro. Its > written > > in basic language and compiled. Runs very fast with a 20 Mhz clock. > > > > At this stage the unit puts out a manchester encoded timecode signal and > is > > injected at the very first data stage on the decoder. You have to do this > > to > > get the PLLs to lock so things decode correctly. I have not attached a > GPS > > time signal to it yet and associated time decoding to automatically sync > > the > > clock. That will be the next item. But I suspect this will be a bit ugly. > > Like sync once per day type of behavior. > > > > Another interesting thing I discovered in this project. That the GOES 100 > > Hz > > timecode actually transports a very stable frequency reference. So you > need > > a pretty good 100 hz source. What this means is the clock will only drift > > as > > much as that source drifts. Thats why I think a single sync 1 time per > day > > is most likely just fine. Additionally the internal 10 MC clock locks to > > the > > 100 HZ and is pretty stable. (Ok now I am in trouble. What on earth does > > that statement mean in this group?) > > > > As with the Loran simulator I will share the information with the group > as > > it shapes up. > > For now I need to make sure the basic software actually is correctly > > keeping > > time. > > > > Regards > > Paul > > WB8TSL > > _______________________________________________ > > 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. > _______________________________________________ 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.
