Locked Re: Meinberg Error #Timesync

Martin G0HDB <marting0hdb@...>

On Thu, Jun 2, 2022 at 06:19 PM, Reino Talarmo wrote:

Hi Art,

Just a minor correction. NetTime does not provide the same functionality as
Meinberg or any other program that supports full NTP protocol.

Extract from Accuracy Notes:
The vast majority of users should find that NetTime more than meets their
needs, however if you have specific requirements for very accurate time, I
recommend that you investigate installing a full NTP client. Although you can
set NetTime to sync more frequently to compensate for an inaccurate system
clock, this isn't really recommended because of the greater strain that it
puts onto the public NTP servers. A full NTP client has extra features to
ensure better time accuracy (normally well below 10 milliseconds even between
time syncs) by adjusting the rate that the system clock runs at.
Hi Reino (and all), one factor that shouldn't be overlooked when deciding which time-sync'ing app to use on a PC is the effect of using an app such as D4 (and also NetTime?) that is based on the SNTP protocol rather than the full NTP protocol implemented by the Meinberg app.

An SNTP app doesn't adjust the clock smoothly, as the Meinberg app does, but can cause step-changes (in either direction); the effect of these is described perfectly and succinctly by the late, much-missed Bill Somerville G4WJS:

"What is sure is that a step adjustment to the PC clock during a receive period will cause an audio stream discontinuity, and that in turn may disrupt all decoding for that period. "

In other words, if you use an SNTP-based app then you can expect to suffer from missed decodes in any Rx period in which a step-change of the PC clock occurs. This missed-decode effect has been observed and verified in practice.

Martin G0HDB

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