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Conference 7.286::fddi

Title:FDDI - The Next Generation
Moderator:NETCAD::STEFANI
Created:Thu Apr 27 1989
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2259
Total number of notes:8590

279.0. "SMF minimum length" by COMICS::WOODWARD (Smile!) Wed Jun 12 1991 07:24

Hi,

When using single mode fibre, is there a 'minimum' distance for the interstation
link (ie do we need to put in attenuators if the link is below 'x' meters and 
what's the value of 'x' ) ?

Thanks,

Steve
T.RTitleUserPersonal
Name
DateLines
279.1Loss, not Distance!LEVERS::KIRKDick KirkWed Jun 12 1991 09:4325
    Hi,
    
    	NOT distance!! The minimum loss must be controlled.
    
    	The system requires a minimum loss of 12 dB. Since cable plants
    vary as to configuration (number of connectors, splices, and cable
    attenuation rate), it's risky to state a minimum required distance.
    You might end up with a loss that's quite different from what you
    expected.
    
    	The single-mode option board installation guide provides some
    information regarding in line loss elements (aka attenuators). It
    states that if your cable plant has between 0 and 6 dB of loss, you
    must install an attenuator with 12 to 16 dB of loss. If the cable plant
    has between 6 and 12 dB of loss, then a 6 to 10 dB loss attenuator must
    be installed. All loss values are for the 1300 nm wavelength.
    
    	The installation guide lists some vendors for these parts. I think 
    Amphenol, AMP, and Aster are among the companies listed.
    
    
    
    Regards, 
    
    	Dick Kirk
279.2ThanksCOMICS::WOODWARDSmile!Wed Jun 12 1991 10:150
279.3SMF dB loss figures ?SNOFS1::STOCKLFranz StocklMon Jan 15 1996 00:3211
Hi,

We are working on an opportunity which requires the use of SMF due to the 
distances between the FDDI Stations. 
My question to the learned audience, what is the maximum dB loss permissable
for Digital gear (DECnis and FECswitch900EF with SMF PMD in the MX power supply 
module ) to work successfully ? 

Minimum 12 dB    Maximum  ?? dB loss.

Regards,  Franz     
279.422 dB max loss (DEC to DEC)NETCAD::MELARAGNIMon Jan 15 1996 07:463
    Maximum loss for a Digital single-mode link is 22 dB. 
    
    bill