[time-nuts] Sound cards

Lux, James P james.p.lux at jpl.nasa.gov
Tue Jan 13 18:12:05 EST 2009


Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Magnus Danielson
> Sent: Tuesday, January 13, 2009 3:01 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Sound cards
>
> L
> >
> > Consumer audio optical links (TOSlink) are 1000 micron
> (yes, it sounds
> > better than 1mm) plastic fiber, which is fairly high loss
> (1000 dB/km), which is fine for 1-2 m cables.  TOSlink is
> actually a trademark of Toshiba
> http://www.toshiba.com/taec/components/ProdLineGuide/toslink.p
> df describes all.
> >
> > TOSlink has worked fine for me, except in one case, where
> the cable was flexed a lot, and it eventually developed
> cracks and the loss shot up.
>
> Trouble is, many want some 10 m runs.

Exactly.. I was just down in the lab, and looked at the cables we have strung all over the place, and for us, a 2m cable is positively short.  An awful lot of 5m and 10m cables just patching one thing to another (consider going from a connector on a piece of equipment in one 2m high rack to a connector in another 2m rack.  There's 3-4 m just in going up and down, not to mention the meter or so across, if the racks happen to be side by side.

There ARE fancier cables and connectors in the same family that have more range, but are still pretty cheap components.

The galvanic isolation and EMI immunity IS attractive.  But, a piece of RG-58 sized coax and BNC connectors is awfully common and convenient.








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