From: Marc La Porte (marc.a.laporte@gmail.com)
Date: Thu Jul 03 2008 - 13:00:14 ART
John,
http://en.wikipedia.org/wiki/Digital_Signal_1
It's because of frame synchronization. Frame synchronization is necessary to
identify the timeslots within each 24-channel frame. Synchronization takes
place by allocating a framing, or 193rd, bit. This results in 8 kbit/s of
framing data, for each DS1. Because this 8-kbit/s channel is used by the
transmitting equipment as overhead, only 1.536 Mbit/s is actually passed on
to the user. Two types of framing schemes are Super Frame (SF) and Extended
Super Frame (ESF). A Super Frame consists of twelve consecutive 193-bit
frames, whereas an Extended Super Frame consists of twenty-four consecutive
193-bit frames of data. Due to the unique bit sequences exchanged, the
framing schemes are not compatible with each other. These two types of
framing (SF and ESF) use their 8 kbit/s framing channel in different ways.
Marc
On Thu, Jul 3, 2008 at 5:54 PM, John <jgarrison1@austin.rr.com> wrote:
> The speed that I've always known is 1544 kbs. Now in almost all of the IE
> labs it's 1536 kbs. I've searched (probably in the wrong places) and all I
> get is 1544. Where in the heck are they coming up with 1536.... EU-T1?
>
>
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