Received: from snow-white.ee.udel.edu by whimsy.udel.edu id aa16349; 20 Mar 97 17:22 GMT Received: (from juha@localhost) by samuraj.c3l.tyreso.se (8.8.5/8.8.5) id SAA17457; Thu, 20 Mar 1997 18:22:43 +0100 Date: Thu, 20 Mar 1997 18:22:43 +0100 From: Juha Sarlin Message-Id: <199703201722.SAA17457@samuraj.c3l.tyreso.se> To: Mills@huey.udel.edu CC: stenn@whimsy.udel.edu Subject: Re: loopfilter fix Your ntpsim calculates the time constant like this: tau = 1 << (poll - 2); and ntp_loopfilter.c does: time_constant = min(peer->ppoll, sys_poll) - NTP_MINPOLL; where NTP_MINPOLL is 4. To get similar PLL behaviour you would need to change this calculation or the loop parameters CLOCK_PHASE and CLOCK_FREQ. I'm currently using an xntpd with these changes, in addition to my earlier changes: *** xntpd/ntp_loopfilter.c.~1~ Fri Mar 13 01:18:06 1997 --- xntpd/ntp_loopfilter.c Fri Feb 13 01:21:10 1997 *************** *** 197,201 **** last_time = current_time; interval = current_time - last_time; ! time_constant = min(peer->ppoll, sys_poll) - NTP_MINPOLL; clock_adjust = 0; offset = fp_offset->l_f; --- 197,201 ---- last_time = current_time; interval = current_time - last_time; ! time_constant = min(peer->ppoll, sys_poll) - NTP_MINPOLL + 2; clock_adjust = 0; offset = fp_offset->l_f; *************** *** 430,434 **** */ } else { ! time_constant = NTP_MINDPOLL - NTP_MINPOLL; stmp = (offset / interval) << 4; if (stmp < 0) --- 430,434 ---- */ } else { ! time_constant = NTP_MINDPOLL - NTP_MINPOLL + 2; stmp = (offset / interval) << 4; if (stmp < 0)