MT9074
Advance Information
Frame # Ft
Fs Notes Frame # Ft
Fs Notes Frame # Ft
Fs
Notes
1
2
1
0
1
0
1
0
1
0
1
0
1
0
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
1
0
1
0
1
0
1
0
1
0
1
0
C
o
n
c
e
n
t
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
1
0
1
0
1
0
1
0
1
0
1
0
0
0
0
1
1
1
0
0
0
1
1
1
R
e
s
y
n
c
h
r
X
X
X
X
X
X
X
X
X
X
X
S
S
S
C
C
C
A
A
L
S = Spoiler Bits
3
4
5
6
C = Maintenance Field Bits
7
8
r
9
a
t
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
o
n
i
o
r
A = Alarm Field Bits
z
a
t
F
i
i
e
l
L = Line Switch Field Bits
o
n
d
L
d
a
t
B
i
L
t
L
a
s
S
S = Spoiler Bits
Table 9 - SLC-96 Framing Structure(T1)
E1 Digital Interface
PCM 30 time slot 0 is reserved for basic frame
alignment, CRC-4 multiframe alignment and the
communication of maintenance information. In most
configurations time slot 16 is reserved for either
Channel Associated Signalling (CAS or ABCD bit
signalling) or Common Channel Signalling (CCS).
The remaining 30 time slots are called channels and
carry either PCM encoded voice signals or digital
data. Channel alignment and bit numbering is
consistent with time slot alignment and bit
numbering. However, channels are numbered 1 to 30
and relate to time slots as per Table 10.
PCM 30 (E1) basic frames are 256 bits long and are
transmitted at a frame repetition rate of 8000 Hz,
which results in an aggregate bit rate of 256 bits x
8000/sec = 2.048 Mbits/sec. The actual bit rate is
2.048 Mbits/sec +/-50 ppm encoded in HDB3 format.
The HDB3 control bit (page 01H, address 15H, bit 5)
selects either HDB3 encoding or alternate mark
inversion (AMI) encoding. Basic frames are divided
into 32 time slots numbered 0 to 31, see Figure 34.
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.
PCM
Timeslots
30
0
0
1,2,3...15 16 17,18,19,... 31
1,2,3...15 16 17,18,19,... 31
Voice/Data
Channels
(DSTi/o
and
It should be noted that the Mitel ST-BUS also has 32
channels numbered 0 to 31, but the most significant
bit of an eight bit channel is numbered bit 7 (see
Mitel Application Note MSAN-126). Therefore, ST-
BUS bit 7 is synonymous with PCM 30 bit 1; bit 6
with bit 2: and so on (Figure 34).
CSTi/o)
Table 10 - STBUS vs. PCM-30 to Channel
Relationship(E1)
16
MITEL [ MITEL NETWORKS CORPORATION ]
