Uwe, I checked NPL telephone and found it uses the * and # as per PTB. The exisitng driver code captures a timestamp at the beginning of the timecode message and at the * and # characters at the end. According to the NPL, the * or # is transmitted as the last character of the message, which is within one character (CR) of the first bit of the LF on-time event. However, the reported PTB timestamp is in error much more than that.
Question about the baud rate. NPL does not specify the baud rate; PTB specifies 1200 bps. At 1200 bps a 10-bit characgter takes 8.33 ms, so the 78-character message takes 650 ms. If the * or # was not found, the error would be near 650 ms; however, if it was found the error should depend only on the ISDN delay, which in your case is about the same here. In other words, the 51-ms error is probably due to the ISDN delay and the \\ scheme would compensate for that. Dave Uwe Klein wrote: > [EMAIL PROTECTED] wrote: > >> Heiko, >> >> While this has nothing to do with the second server you cite, the >> 51-ms discrepancy between the PTB and GPS time is rather large. Either >> the telephone or modem delay is unexpectedly large or the timecode >> timestamp is at the wrong on-time character. > > It's all ISDN and digital transfer in the Xchange? > ( I get around 35/45 ms roundtrip delay via ISDN raw IP ) > > uwe _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
