Re: 850 nm solutions
Hi Jim,
the simple answer is that you will never meet 100m for installed orr 300m
for new fiber. A serial 850nm will barely meet 300m over new fiber, but will
be well below 100m for installed fiber.
Stefan Wurster
408-499-5005
smwcom@xxxxxxxx
----- Original Message -----
From: Tatum, Jim <JTatum@xxxxxxxxxxxxxxxxxxx>
To: Jaime Kardontchik <kardontchik.jaime@xxxxxxxxxxx>; stds-802-3-hssg
<stds-802-3-hssg@xxxxxxxx>
Sent: Tuesday, April 18, 2000 12:44
Subject: RE: 850 nm solutions
>
>
> I guess I don't understand all of the problems here...
>
> Why can't we have a serial solution at 850nm and 1310nm, 1550nm that
mirrors the 802.3Z approach, where we have a table that addresses each of
the fiber types. i.e. repeat the tables 38.2 and 38.5. Seems like an easy
thing to do, and straightforward. That is one PMD type. A second PMD type
would be the 4 wavelength WDM at 3.125GBd, with a similar table. To me
that is 2 PMD's, with options, with link lengths depending on what fiber
you have installed. The market has shown that 850nm technology is the low
cost approach.
>
> -Jim
>
> __________________________Honeywell
>
> Jim Tatum
> (972) 470-4572
> http://www.honeywell.com/sensing/vcsel
>
> -----Original Message-----
> From: Jaime Kardontchik
> Sent: Tuesday, April 18, 2000 2:07 PM
> To: stds-802-3-hssg
> Subject: 850 nm solutions
>
>
> Edward and all,
>
> Thank you Edward for your insight.
>
> There are have been in Albuquerque excellent presentations
> using 850 nm VCSELs by J. Yorks, P. Kolesar et al, F. Peters,
> R. Colla et al and J. Jewell. They were all targetted towards
> the new 2200 MHz*km MMF using 10 Gbaud lasers. Unfortunately,
> at this speed they cannot support the installed MMF (the
> eye closes at about 25 meters).
>
> However, there are two proposals using 850nm - 4WDM that
> do support both the installed MMF and the new 2200 MHz*km
> MMF. See the Albuquerque presentations:
>
> B. Wiedemann et al: "Evaluating CWDM 10GBASE-SX"
>
> and
>
> J.E. Kardontchik et al: "850nm-4WDM-1.25Gbaud transceiver
> over MMF for 10 GbE"
>
> Both provide ample support for the new MMF: the first
> proposal, at 2.578 Gbaud, has a target of 550 meters, and
> the second proposal, running at 1.25 Gbaud, has a target
> of 1,000 meters. Hence, both meet with ample margin
> the minimum objective of the HSSG regarding the new
> 2200 MHz*km MMF, 300 meters.
>
> The 2.578 Gbaud proposal has a target of 100 meters on
> installed MMF. The 1.25 Gbaud proposal has a target of
> 160 meters on installed MMF. Hence, both meet also the
> minimum objective of the HSSG regarding the installed
> MMF, 100 meters.
>
> The 2.578 Gbaud proposal has the advantage of using
> on-off optical modulation. Its PCS, using 64/66, is new
> and needs still some work and debugging in the coming
> months. Work is being presently done in both areas to
> validate this proposal. It is a very good proposal.
> I happen to co-sponsor it ... :-)
>
> The 1.25 Gbaud proposal uses PAM-5 modulation, that
> is new to the optical community. However, it only needs a
> very small dynamic range (18-level ADC in the receiver),
> corresponding to an SFDR (Spurious Free Dynamic Range)
> of about
>
> SFDR = 20*log(18) + (2/3)*10*log(0.625e+9)
> = 84 dB*Hz^(2/3)
>
> This SFDR is well within the present VCSEL technology
> capabilities. (*) This proposal has the advantage that it reuses
> the 1000BASE-T PCS, that has already been debugged and
> standardized and some companies are already offering it
> in commercial products. It uses the same symbol rate as
> the 1 GbE optical transceivers, 1.25 Gbaud, simplifying
> the coexistence of 1 and 10 GbE transceivers on the same
> board and minimizing packaging and PCB costs and EMI.
> It could be the lowest cost 10 GbE system solution on MMF,
> both installed and new.
>
> The only area that needs detailed work, in order to meet
> the July 2000 schedule-milestone, is in providing actual
> 5-level pseudorandom stimulus to VCSELs at 1.25 Gbaud
> and measuring the actual performance of the optical link.
> My company has shown a lot of support towards developing
> the whole proposal. However, it does not have the means
> and optical expertise in this area and we will welcome
> any optical companies interested in performing these
> measurements and presenting them to the Task Force.
>
> These are the 850 nm choices.
>
> (*) See, for example:
>
> "Dynamic Range of VCSELs in Multimode Links"
> by: H.L.T. Lee, R.V. Dalal, R.J. Ram and K.D. Choquette
> IEEE Photonics Tech. Letters, vol 11, pp 1473-75, Nov 1999
>
> Jaime E. Kardontchik
>
>
> Edward Chang wrote on Mon, 17 Apr 2000 12:16:33 -0400:
>
> > Brad:
> >
> > I appreciate your input, and we may have to speed up the proposal by
quickly
> > responding to some questions.
> >
> > My main concern is that the sole technology, 850 nm VCSEL, which
created
> > today's cost-effective gigabit rate LAN market is not included in the
> > proposal. The VCSEL technology will continue to play the major role in
the
> > 10 GbE market to keep the cost affordable and to open up the market.
> > Following the lead by the more affordable technology, the more
expensive
> > technologies will be demanded by the market needs. This was the
sequence
> > happened in the Gigabit rate market.
> >
> > The mass market is always looking for the top performance at lowest
cost.
> >
> > It is true that July is approaching very quick, and we should speed up
the
> > process.
> >
> > Nevertheless, our good common since taught us that do it "Right" is the
key
> > to the success.
> >
> > I believe all of us had some regrettable experience: overly rigid to
follow
> > the rules set at the beginning, and not enough flexibility to
accommodate
> > the reality uncovered later.
> >
> > The mission of HSSG is to provide the right directions for 10 GbE
industry;
> > therefore, we should continue to evaluate the over all progress and
maintain
> > good balance.
> >
> > Regards,
> >
> > Edward S. Chang
> > NetWorth Technologies, Inc.
> > EChang@xxxxxxxxxxxxxxxx
> > Tel: (610)292-2870
> > Fax: (610)292-2872
>
>