From owner-freebsd-current  Mon Mar  8  7:18:40 1999
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Date:     Mon, 8 Mar 1999 10:12:23 EST
From: Dave Mills <mills@huey.udel.edu>
To: Pierre Beyssac <pb@fasterix.freenix.org>
Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>,
	Dave Mills <mills@huey.udel.edu>,
	Ollivier Robert <roberto@keltia.freenix.fr>, current@freebsd.org,
	Harlan Stenn <Harlan.Stenn@pfcs.com>,
	"David L . Mills" <mills@udel.edu>
Subject:  Re:  NTP nanokernel support (experimental)
Message-ID:  <199903081012.aa20781@huey.udel.edu>
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Pierre,

The NTPv4 driver interface already implements a trimmed-mean filter, which
cleans up a good deal of jitter as it is. The IRIG and CHU drivers do a
lot more signal processing, yielding generally low jitter in the tens
of microseconds. Deglitching and filtering noisy time sampls is somewhat
an art form, but the methods are not hard to implement.

Dave


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