Date: Sat, 11 Jul 1998 10:56:58 +0100 (BST) From: Duncan Barclay <dmlb@ragnet.demon.co.uk> To: Peter Jeremy <peter.jeremy@alcatel.com.au> Cc: hackers@FreeBSD.ORG Subject: RE: PPS device Message-ID: <XFMail.980711105658.dmlb@computer.my.domain> In-Reply-To: <199807110052.KAA07523@gsms01.alcatel.com.au>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.980711105658.dmlb>