[SI-LIST] Re: question Optical Tranceivers
- From: Yafei Bi <yafei_bi@xxxxxxxxx>
- To: jan.vercammen1@xxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Fri, 8 Oct 2004 13:35:18 -0700 (PDT)
hi,
I don't know much about optical devices, so I might be
wrong.
I assume during the transmission of data, the laser is
not ON and OFF. Rahter it is always on and the
power/intensity of the laser is modulated to transmit
the data.
There are 2 ways to transmit data with opto
transmitter I can think of:
1. on/off switching, this will limiting the speed.
with Gbit ethernet, I doubt it is the case.
2. keep laser on and doing some sort of phase
modulation, eg. split the laser into two and phase
shift one of the laser, and then adding them together.
depends on the phase shift( 0 or 180 degree). the
combined laser output power will be zero or full
power, that way data is encoded.
just my guess.
Thanks
yafei
--- jan.vercammen1@xxxxxxxx wrote:
> hello SI-list,
> I am forwarding a question of a colleague:
>
> We are evaluating optical transceivers (Gbit
> Ethernet and Fibrechannel
> devices) for IEEE-1394 communication on GOF. The
> IEEE-1394 protocol issues
> a pulsed signal into the opto transmitter: every
> 40msec a small burst of
> some 660usec containing 20nsec pulses is generated.
> In between the bursts
> the signal is steady (high). The transmitter of the
> transceiver is always
> ENABLED, tied to GND.
>
> We find that not all optical transceivers are
> working with such an input
> signal: some devices do not emit light at all.
> We think that there is maybe a laser start-up time,
> i.e. the burst of
> 660usec is too short for some transceivers to start
> emitting light.
> However, we cannot find any indication in the spec
> or datasheet.
> 1. We would like to understand why certain
> transceivers do not transmit
> and others do?
> 2. And how to spot that from a datasheet?
>
> Many thanks in advance,
> Patrick Lambrechts
>
> Kind regards,
>
> Jan vercammen
>
>
------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in
> the Subject field
>
> or to administer your membership from a web page, go
> to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the
> Subject field
>
> List FAQ wiki page is located at:
>
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are
> viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
__________________________________
Do you Yahoo!?
Yahoo! Mail - Helps protect you from nasty viruses.
http://promotions.yahoo.com/new_mail
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
