Hi Have an alarm go off on your PC and do the correction once a month.
Bob On Dec 8, 2012, at 8:56 PM, Chris Albertson <albertson.ch...@gmail.com> wrote: > So the goal then is automate the process, not to make it better. I figure > once you have an easy-to-modify and easy-to-replicate design up and running > then with many people able to experiment the performance will improve. > > You can almost not count the cost of the Arduino. This is a self contained > part that can be used in many projects. Same with a 12VDC power supply. > Lots of people like to play with these and have them already. > > So,.... as for performance, let's just say for not that it only has to > work as well as one could do by hand and eye and a 'scope. Let's say 10E-8 > > > What if I use a flip flop. The PPS from the GPS connects to the "set" > input of the FF and also to the Arduino interrupt. The output of the OCXO > goes to the reset pin of the same FF. > > The interrupt handler reads the value of the FF. It will be either 1 or 0 > depending if the phase of the OCXO leads or lags the phase of the PPS. The > software will try to keep the FF average value at exactly 0.500 > > > > > On Sat, Dec 8, 2012 at 4:25 PM, Bob Camp <li...@rtty.us> wrote: > >> Hi >> >> A standard that is good to "8 digits" can be done manually. That's far >> cheaper than your goal and the software is totally open source. It can be >> done with off the shelf parts and no wiring at all. >> >> Problem solved? >> >> I suspect not…. >> >> Bob >> >> On Dec 8, 2012, at 1:59 PM, Chris Albertson <albertson.ch...@gmail.com> >> wrote: >> >>> On Sat, Dec 8, 2012 at 9:30 AM, <johncr...@aol.com> wrote: >>> >>>> Hello all - >>>> >>>> "People talk about good deals on Thunderbolts but I have >>>> yet to see one. It seems peak Thunderbolt passed before I was >>>> seriously looking." >>>> >>>> >>>> *The box you put it in - suspending it above the bench on inspirational >>>> thought probably >>>> will not work. A nice box is easily $ 50.00 so who cares about adding >>>> another flip flop or >>>> counter at 25 cents each. >>> >>> >>> >>> The goal, well my goal is to build a GPSDO to this set of requirements >>> >>> 1) well under 1/2 the cost of the t-bolt. >>> 2) can be made with common parts and skills most people have >>> 3) is completely modifiable (open source software) >>> >>> So #1 above means you use a low cost box, perhaps the case and old CDROM >>> was once housed in or maybe you gut and old PC chassis >>> >>> #2 pretty much means you have to keep theparts cound way down. Yes a >> chip >>> might cost only $1 but as soon as you get more then about three of those >> 25 >>> cent cips you need a PCB. PCB making is not a common everyday skill so >> #2 >>> means a way-low parts count >>> >>> #3 means the uP is gong to have to come with a very easy to use and free >>> open source toolchain. Adruino is like that, there are others, but a >> bare >>> uP chip is not going to work >>> >>> >>> You are right that one way to engineer a product is to first set >>> performance numbers. But another more common way is to first identify a >>> target customer and then set a target price. In this case the target >>> customer is a hobbyist with only basic skills who wants a low cost easy >> to >>> build GPSDO that has can understand and modify himself. >>> >>> Next with those very hard to meet requirements (low cost, low parts >> count, >>> simple to build) we can ask if the exected perfomance is "good enough" >>> What is good enough. I'd say if you could use the GPSDO a a local >>> frequency standard for a counter that has 8 digits you are doing "well >>> enough". If you can get to 10 digital it is pretty good >>> >>> -- >>> >>> Chris Albertson >>> Redondo Beach, California >>> _______________________________________________ >>> 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. >> > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > 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.