In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] (Greg Dowd) wrote: [ Pretty sure the threading is broken after this! ]
> If I understand correctly, the question regards slew rate limits. In an That's not my understanding. My understanding is that he want to constrain the first derivative of the frequency correction. That is the second derivative of the offset. Slew rate is used to describe the frequency correction, particular when it is being used to reduce an offset error. What's probably implicit is that, in the specification he is trying to implement, this is the derivative including the first derivative of the crystal frequency, so the 25mHz/27MHz/s (about 0.001 ppm/s) might be totally taken up by variations in the crystal frequency. Actually, given that he wants this condition met after one minute, but the machine probably won't reach thermal equilibrium for more like 15 minutes, I think it will almost certainly be violated by the crystal frequency on its own. In that case, the only way of achieving conformance is to NOT constrain the first derivative of frequency correction, so that there is some chance of the frequency being compensated fast enough to compensate for the crystal drift. [ Further note on threading. This is a newsgroup to which an email gateway has been added. If you reply to a digest, on the email side, you are likely to generate a thread link to the digest, which never appears on the newsgroup, rather than the message to which you are replying. ] _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
