Re: questions on PCS synchronization : state diagram
Wesley,
To answer your question directly, if you are in UNLOCK state, you will
always see a very hi ber and so if you wait for it go low ber
before you start acquiring sync, you will forever be stuck in
the UNLOCK state.
It will help to separate out the two processes going on here:
sync_lock and sync_done.
sync_lock: This process should be independent of the hiber monitor.
You are in sync lock if you have 64 contiguous valid syncs. You are
out of sync_lock if you have atleast 32 invalid syncs in a measurement
of 64 frames. If you find you are out of sync, you "slip by a bit" and
check if you have valid sync and repeat till sync_lock.
sync_done: You are sync_done iff you are sync_lock and hiber monitor
says it is not a hiber situation.
As you pointed out, the hiber acts only as a qualifier
so you could redraw the diagram with one less state.
-------------
| sync_lock |
-------------
^ \
| \
| \ ___________
| unlock \
|lock \
| unlock \-->
-------------- ----------->--------
| sync_unlock |/ | slip |
-------------- <--------- --------
^ slip_done
|
|
Start
and sync_done = sync_lock & ~hiber
regards,
Birdy
----------------------------------------------------------------
Hi Birdy,
I have a question regarding this state diagram. It appears that
the HIBER state relative to the LOCK state really has no
purpose. The same conditions ("unlock") would bring the
state machine to SLIP. My question is - is the purpose of
the HIBER state is to use it as a qualifier for going into
the LOCK state. In other words, if we currently in UNLOCK,
and if we start seeing a high BER, them we must first see
a low BER before looking at the sync bits.
=============================================
Netscape munged up my state diagram. I am
resending it.Hope it comes ok this time.
hiber
------- ------------> -------
| LOCK | / | HIBER |
------- < _____________ / -------
^ \ ~hiber |
| \ |
| \ ______ | unlock
| unlock\ |
|lock \ |
| unlock \--> V
--------- ---------> --------
| UNLOCK |/ | SLIP |
--------- <--------- --------
^ slip_done
|
|
Start
regards,
birdy
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