[time-nuts] Sound cards

Magnus Danielson magnus at rubidium.dyndns.org
Tue Jan 13 18:48:18 EST 2009


Lux, James P skrev:
> 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.

On the other hand, I am used to stretch out for a 25 km or 50 km roll of 
fiber. Works very well for 2,5 Gb/s or 10 Gb/s links.

The price for decent enought multimode should be more or less dirt cheap 
by now, and we are talking real glas.

Cheers,
Magnus




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