Instaled and testing, thanks by the initiative Coberllini Regards Carlos Bella ** 2013/9/3 satrack@libero.it <satrack@libero.it> > Hi George, > > many thanks for your test and suggestions. In the next release I will show > more > details on the correction factor. I will also improve its determination as > suggested. > (Initially, the program was programmed to use the top 1 synch, but it was > not > useful during tests when I wanted to see the result of each synch). > > The shown Tacc is equal to the round trip time (RTT) divided by 2. The time > error is computed as the difference between the time of the request +RTT/2 > and > the server time. Therefore, in your example it would be indeed 1.8 s. > > The mean Tacc from my location is of about 80 ms. Unfortunately, one of the > main > problems with mobile phones is the network latency. I partially solved this > problem > engaging the network with a short data transfer during which I perform > the time synchronization. Without this trick the situation would be even > worse, > with RTTs even larger than 0.5 s. > > I introduced the item "exit" in the menu since I decided to capture the > "back" > key > as input for the stopwatch. This menu item should terminate the > application. > > It would be interesting if someone could test the time deviation with > respect > to > a reference clock. > > Regards, > Simone > > > > >Very Nice! > > > >1) I love the way I can press up volume, down volume, or back button and > get > >3 different time indicators so later I know which one was which. One can > >use this to help remember which event is which - for example press the vol > >up button when the sat is closest to a known and planned-for bright star > and > >the vol down button when the sat is closest to an unknown fainter star. > >2) I love that I can jump into timing an event, then later sync up several > >times until I get a higher accuracy. Each time I sync all the times > adjust > >slightly to the latest syncing. > >3) Unfortunately the highest accuracy I was able to get with about 30 > >attempts was "Tacc < 90ms". This is according to the program (not tested > >against something more accurate). > >4) It would be nice to display the correction factor you are using. The > >correction factor for my phone was about 1 second. > >5) It would be nice to be able to take an average of the top 3 sync events > >or the top 1 sync event and not update the times displayed unless the > latest > >sync event had a "Tacc" better than any previous ones. > >6) I assume Tacc is the same as the round trip network time. Do you use > >this information in the syncing? In other words if the phone says it is > 1.0 > >seconds after the hour and the NTP server says it is 3.0 seconds after the > >hour and the round trip delay was 0.4 seconds, do you use a correction > >factor of 2.0 seconds or a correction factor of 1.8 seconds? (this assumes > >the .4 sec delay was equal on both paths or .2 seconds each way). > >7) The "exit application" doesn't seem to work but I'm not sure what its > >purpose is anyway. I would just get rid of it. > > > >- George Roberts > >http://gr5.org > > > >_______________________________________________ > >Seesat-l mailing list > >http://mailman.satobs.org/mailman/listinfo/seesat-l > > > > > _______________________________________________ > Seesat-l mailing list > http://mailman.satobs.org/mailman/listinfo/seesat-l > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://mailman.satobs.org/mailman/private/seesat-l/attachments/20130903/def24534/attachment.html _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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