On 2012-03-10, alex n <alexv...@gmail.com> wrote: > 2012/3/10 Dave Hart <h...@ntp.org> > >> On Sat, Mar 10, 2012 at 13:08, alex n <alexv...@gmail.com> wrote: >> > xGPS_NMEA(0) .NV24. 0 l 9 16 377 0.000 0.021 >> 0.004 >> > oPPS(0) .PPS. 0 l 7 16 377 0.000 >> 0.020 0.004 >> > >> > GPS_NMEA is nmea driver with pps support. Why GPS is falseticker >> > though it has a same offset as PPS? >> >> Are both drivers using the same PPS signal? > > > Yes, it is so. > > >> If so, what do you hope to gain? > > > Why the same source (PPS) may not be shared?
You show it does. But why? It is the same source. Note that if this is not the same source-- ie is attached to different interrupts ( parallel and serial ports for example) you will have interrupt contention. One of the interrupts will be seen by the computer as occuring first, and will be serviced first. Interrupts are turned off while the interrupt is serviced. Thus there is a 10-20us delay before the other interrupt is serviced. Ie, the two interrupts will not be timed to occur at the same time. They will have timestamps that differ by 10s of us. Now if it is the same interrupt that you are sending to two separate handlers, the question really is "why". There is no extra information that the two can give you. > > Thanks, > Alex. _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions