From owner-freebsd-hackers Sat Jul 11 04:27:08 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id EAA26483 for freebsd-hackers-outgoing; Sat, 11 Jul 1998 04:27:08 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from post.mail.demon.net (post-12.mail.demon.net [194.217.242.41]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id EAA26475 for ; Sat, 11 Jul 1998 04:27:04 -0700 (PDT) (envelope-from dmlb@ragnet.demon.co.uk) Received: from (ragnet.demon.co.uk) [158.152.46.40] by post.mail.demon.net with smtp (Exim 1.82 #2) id 0yuxny-000014-00; Sat, 11 Jul 1998 11:27:02 +0000 Received: from dmlb by ragnet.demon.co.uk with local (Exim 1.82 #1) id 0yuwOo-0005QQ-00; Sat, 11 Jul 1998 10:56:58 +0100 Message-ID: X-Mailer: XFMail 1.2 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <199807110052.KAA07523@gsms01.alcatel.com.au> Date: Sat, 11 Jul 1998 10:56:58 +0100 (BST) From: Duncan Barclay To: Peter Jeremy Subject: RE: PPS device Cc: hackers@FreeBSD.ORG Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 11-Jul-98 Peter Jeremy wrote: > Is anyone using a PPS device with FreeBSD? I notice that -current > includes support for a PPS source attached via a parallel port. > [snip] > BTW: Anyone looking for a good stand-alone reference might like to look > at the master reference oscillators in digital cellular base stations - > the GSM standard (which also covers DCS-1800 and DCS-1900) requires > a 0.05ppm or better reference in the base station. I suspect DAMPS and > CMDA also have similarly tight tolerances. Whilst these references are > expensive new, if you know someone in the industry, you might be able > to acquire one from a junked board. That's a neat idea! If you can cope with a slightly relaxed tolerance of 1ppm get a 13MHz TVCXO (temperate/voltage controlled crystal oscillator) for handset use. These will be cheap, a couple of dollars I guesss (I only ever know prices by the millions:-)). There're probably smaller than the base station version too. The handset TCXOs have a voltage control function too, so if you got clever you could do a hardware trim of them too. Duncan --- ________________________________________________________________________ Duncan Barclay | God smiles upon the little children, dmlb@ragnet.demon.co.uk | the alcoholics, and the permanently stoned. ________________________________________________________________________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message