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MT9074AL 参数 Datasheet PDF下载

MT9074AL图片预览
型号: MT9074AL
PDF下载: 下载PDF文件 查看货源
内容描述: T1 / E1 / J1单芯片收发器 [T1/E1/J1 Single Chip Transceiver]
分类和应用: 电信集成电路
文件页数/大小: 122 页 / 371 K
品牌: MITEL [ MITEL NETWORKS CORPORATION ]
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MT9074  
Advance Information  
appropriate mode and Jitter attenuation capability of  
the MT9074  
The most significant bit of an eight bit ST-BUS  
channel is numbered bit 7 (see Mitel Application  
Note MSAN-126). Therefore, ST-BUS bit 7 is  
synonymous with DS1 bit 1; bit 6 with bit 2: and so  
on.  
The Digital Interface  
T1 Digital Interface  
Frame and Superframe Structure in T1 mode  
In T1 mode DS1 frames are 193 bits long and are  
transmitted at a frame repetition rate of 8000 Hz,  
which results in an aggregate bit rate of 193 bits x  
8000/sec= 1.544 Mbits/sec. The actual bit rate is  
1.544 Mbits/sec +/-50 ppm optionally encoded in  
B8ZS format. The Zero Suppression control register  
(page 1, address 15H,) selects either B8ZS  
encoding, forced one stuffing or alternate mark  
inversion (AMI) encoding. Basic frames are divided  
into 24 time slots numbered 1 to 24. Each time slot is  
8 bits in length and is transmitted most significant bit  
first (numbered bit 1). This results in a single time  
slot data rate of 8 bits x 8000/sec. = 64 kbits/sec.  
Multiframing  
In T1 mode, DS1 trunks contain 24 bytes of serial  
voice/data channels bundled with an overhead bit.  
The frame overhead bit contains a fixed repeating  
pattern used to enable DS1 receivers to delineate  
frame boundaries. Overhead bits are inserted once  
per frame at the beginning of the transmit frame  
boundary. The DS1 frames are further grouped in  
bundles of frames, generally 12 (for D4 applications)  
or 24 frames (for ESF - extended superframe  
applications) deep. Table 7 and 8 illustrate the D4  
and ESF frame structures respectively.  
For D4 links the frame structure contains an  
alternating 101010... pattern inserted into every  
second overhead bit position. These bits are  
intended for determination of frame boundaries, and  
they are referred to as Ft bits. A separate fixed  
pattern, repeating every superframe, is interleaved  
with the Ft bits. This fixed pattern (001110), is used  
to delineate the 12 frame superframe. These bits are  
referred to as the Fs bits. In D4 frames # 6 and #12,  
the LSB of each channel byte may be replaced with  
A bit (frame #6) and B bit (frame #12) signalling  
information.  
It should be noted that the Mitel ST-BUS has 32  
channels numbered 0 to 31. When mapping to the  
DS1 payload only the first 24 time slots and the last  
(time slot 31, for the overhead bit) of an ST-BUS are  
used (see Table 6). All unused channels are tristate.  
When signalling information is written to the MT9074  
in T1 mode using ST-BUS control links (as opposed  
to direct writes by the microport to the on - board  
signaling  
registers),  
the  
CSTi  
channels  
corresponding to the selected DSTi channels  
streams are used to transmit the signalling bits.  
For ESF links the 6 bit framing pattern 001011,  
inserted into every 4th overhead bit position, is used  
to delineate both frame and superframe boundaries.  
Frames #6, 12, 18 and 24 contain the A, B, C and D  
signalling bits, respectively. A 4 kHz data link is  
embedded in the overhead bit position, interleaved  
between the framing pattern sequence (FPS) and the  
transmit CRC-6 remainder (from the calculation done  
on the previous superframe), see Table 8.  
Since the maximum number of signalling bits  
associated with any channel is 4 (in the case of  
ABCD), only half a CSTi channel is required for  
sourcing the signaling bits. The choice of which half  
of the channel to use is selected by the control bit  
MSN (page 01H address 14H). The same control bit  
selects which half of the CSTo channel will contain  
receive signaling information (the other nibble in the  
channel being tristate). Unused channels are tristate.  
DS1 Timeslots  
1
0
2
1
3
2
4
3
5
4
6
5
7
6
8
7
9
7
10 11 12 13 14 15 16  
Voice/Data Channels  
(DSTi/o and CSTi/o)  
9
10 11 12 13 14 15  
Ds1 Timeslots  
17 18 19 20 21 22 23 24  
-
-
-
-
-
-
-
-
Voice/Data Channels  
(DSTi/o and CSTi/o)  
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31  
x
x
x
x
x
x
x
S
bit  
Table 6 - STBUS vs. DS1 to Channel Relationship(T1)  
14  
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