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Re: Equalization and benefits of Parallel Optics.




ghiasi wrote:

> Hi Ed
>
> > Further Comment:
> >
> > The parallel technique will add more skew than a single fiber to further
> > restrict the distance and cost.
>
> Current base line proposal allocates 16 bit (5.12 ns) of skew to the fiber
> media.  Ribbon fiber worst case skew is 10 ps/m even at 300 m it address to
> 3 ns.  Skew will not restrict the parallel optics distance at 300m.
>

All,

For the sake of comparison between the various parallel
technologies in this small item of skew: my simulations
give a skew between extreme wavelengths in 4-WDM of
100 psec in the 1300 nm window and 2 nsec in the 850 nm
window using  plain MMF and a distance of 300 meters.

Jaime E. Kardontchik
Micro Linear
San Jose, CA 95131

>
>
> >  Ghiasi:
> >
> >  If you have 75% support for 6-PMDs to include parallel-interconnect, I will
> >  vote for parallel, since I support all VCSEL technologies.  Otherwise,
> > 5-PMDs
> >  is sufficient already.
> >
> >  The Parallel approach is mainly for up to 20 meter connections.  It is not
> >  designed for 100 meter to go through ducked, or underfloor pipe
> >  installations, because a ribbon fiber is not jacketed enough for those
> > rough,
> >  punishing pulling environment.  Furthermore, at the patch panel connections,
> >  the fibers are all single (duplex fibers) fibers, but not 4-parallel
> > (duplex)
> >  fibers.  For a parallel fiber to connect to an existing single (duplex)
> > fiber
> >  at the patch panel, one has to perform field termination, to which a
> > parallel
> >  fiber is not designed for due to the tight tolerance of spacing between
> >  adjacent channels.  Normally, the parallel ribbon fiber cable is factory
> >  terminated only.
> >
> >  However, if the parallel fibers are used just as a jumper cable to
> >  interconnect closely located nodes -- 5 meter, 10 meter,-- the ribbon cable
> >  can do the job.  Then, how about the serial 850 nm approach, which is
> >  cheaper, and easier eventually to reach more than 20 meters?
> >
> >  I was a member of OETC consortium in early 1991, which promoted the parallel
> >  interconnect in industry with the blessing from ARPA.  The project failed
> >  several years later due to the lack of interest from industry.  The reason
> >  was too expensive, difficult in termination and alignment, and expensive
> >  ribbon cables.
> >
> >  I was a big fun for, the industry first commercial parallel interconnect,
> >  OCTOBUS.  I tried very hard to implement to my company's equipment.  After
> >  several years, the product never reach production stage, and was canceled,
> >  due to the lack of interest from industry.  The reason was the same as OETC.
> >
> >  There was only two ribbon cable suppliers and was expensive that time.  The
> >  factory only termination was very inconvenient for users.  It implies there
> >  is no flexibility in modifying the cable lengths, when an equipment, or
> >  terminals are rearranged to a different location.  One has to go back to
> >  order new set of cables?
> >
> >  For last 10 years, parallel interconnect was highly valued; however, it was
> >  never motorized as a contender for the top interconnect solutions.  I hope
> > it
> >  will this time?
> >
> >
> >  Regards,
> >  Ed Chang
> >
> >  NetWorth Technologies, inc.
> >
> >   >>