A1 A2 Framing bytes

[Cijo Ceazer]

Hi Huub and others,

The value of SONET A1 A2 bytes has been fixed as 0xF628. Is there any
particular reason for this value? One thing which people told me for
the initial "F", is so as to avoid the occurrence of the particular
pattern in payload itself. As the payload is scrambled, it difficult
to have a pattern of all 1's for consecutive bits. Although it sounds
logical, is there any other reasons for the particular value?

Regards,
Cijo Ceazer.

[Huub van Helvoort]

Hello Cijo Ceazer,

You wrote:

The initial "F" is to provide four consecutive bits for the clock
recovery circuit to lock the clock.
The number of "0" and "1"in F628 is equal (=8) to take care that
there is a DC balance in the signal (after line coding).

It has nothing to do with the scrambling, the patern may even
occur in the scrabled signal, however it is very unlikely that
that occurs exactly every 125 usec so there will not be a false
lock to thsi patteren.

Cheers, Huub.

--
reply to hhelvooort with 2 'o's
================================================================
http://www.van-helvoort.eu/
================================================================
Always remember that you are unique...just like everyone else...

[Cijo Ceazer]

Thanks HuuB :-)