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.
> >
> > >>