Dear Sir,

In SDH, for a frequency offset of +20PPM, the AU4 pointer adjustment
period was observed to be 8 msec for an STM-1 frame with either VC4
filled OR VC12 bulk filled. That is the SDH mux decrement the AU4
pointer every 8 msec to compensate for the drift. Does that mean for
one pointer justification is done over 64 STM frame (8msec/
0.125msec)?? Pl correct me if i am wrong.

In ITU-T G.707, it is mentioned that the one pointer justification
(24bit adjustment) is carried out for consecutive 4 STM-1 frame. My
observation is contradicting this statement. So i am really confused.
Pl help me.

Thanks & Regds

Satheesh

Hi Satheesh,

You wrote:

> In SDH, for a frequency offset of +20PPM, the AU4 pointer adjustment
> period was observed to be 8 msec for an STM-1 frame with either VC4
> filled OR VC12 bulk filled. That is the SDH mux decrement the AU4
> pointer every 8 msec to compensate for the drift. Does that mean for
> one pointer justification is done over 64 STM frame (8msec/
> 0.125msec)?? Pl correct me if i am wrong.

Indeed one pointer justification after *every* 64 STM frames.

> In ITU-T G.707, it is mentioned that the one pointer justification
> (24bit adjustment) is carried out for consecutive 4 STM-1 frame. My
> observation is contradicting this statement. So i am really confused.
> Pl help me.

The statement in G.707 means that at maximum a pointer justification
can occur *every* 4 STM frames. This means that after a frame with a
pointer justification the next three frames shall contain the new
pointer value
so they *cannot* contain another pointer justification.

Hope this helped.

Cheers, Huub.

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That means if the pointer value is say, 43 initially, then after 64
STM1 frame (offset=20PPM), the pointer value decremented by 1 (That is
42) and the process complete till it compensate for the complete
offset.Right sir??

Hi Satheesh,

You continued:

> That means if the pointer value is say, 43 initially, then after 64
> STM1 frame (offset=20PPM), the pointer value decremented by 1 (That is
> 42) and the process complete till it compensate for the complete
> offset.Right sir??

Yes. Note that the offset is constant so in this case there will
be pointer adjustments every 64 STM1 frames to compensate the
difference in frequency of 20 ppm.

Cheers, Huub.

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