ISO-CMOS MT8950
125 µs
Internal
Clock
31
b70
23 24 25 26 27 28 29 30
b4b3b2b1b0=11111
0
0
1
2
3
4
5
6
7
8
9
10
• • •
22
b7-1
Frame Type
#
1
1
1
1
b6
1
b5
1
b4b3b2b1b0
1
1
1
2
1
1
b4b3b2b1b0
0
0
1
1
1
0
3
4
b4b3b2b1b0
b4b3b2b1b0
1
1
1
1
1
0
0
1
5
6
b4b3b2b1b0
b4b3b2
1
b1b0
1
7
0
0
7
0
1
2
3
4
0
1
2
3
4
5
6
Figure 3 - TEM Coding Scheme
(Note: Waveforms shown are bipolar RZ equivalent of separate RZ/NRZ inputs)
†
Frame
Description
Level
b7
Frame Type
b6 b5
First Transition
b4 b3 b2 b1 b0
#
Notes
1
2
3
4
5
6
No Pulse
1/0
1/0
1/0
1/0
1/0
1/0
1
1
1
1
1
0
1
1
1
0
0
1
1 1 1 1 1
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
2 Data Pulses (T=52 µs)
3 Data Pulses (T=52 µs)
1 Data Pulse
X X X X X ≤ 10001 (17)
X X X X X ≤ 00100 (4)
X X X X X = 0 to 31
X X X X X = 0 to 31
X X X X X > 00011 (3)
Violation Pulse
2 Data Pulses (T=104 µs)
(Timeslot 4 to 31)
7
2 Data Pulses (T=104 µs)
(Timeslot 0 to 3)
1/0
0
0
Y Y Y X X
XX = 0 to 3
YYY = 0 to 7
Table 2. TEM Coding Summary
† Note: The Level bit (b7) indicates the level (HIGH or LOW) of the input data in timeslot 31 of the current frame.
of seven frames types are possible as shown in
Figure 3. In frame type 7, the first five bits (b0 to b4)
are used to represent two transitions instead of the
normal first transition. Note that the data transitions
The decoder stage regenerates the original data
from the 8 bit TEM word. The absolute values of the
data signal in the present and previous frames as
given by b7(n) and b7(n-1) are EX-ORed and the
result in combination with the remaining bits of the
TEM word is used to reproduce the original data with
an accuracy of ± 3.906µs (see Table 2). Due to the
data speed restriction above 8 kbps, the second and
third transitions (if any) will be reproduced at
in Figure 3 are shown as a three level signal.
A
positive transition indicates the beginning of one or
more continuous MARKs and a negative transition
indicates the beginning of one or more continuous
SPACEs.
6-7
MITEL [ MITEL NETWORKS CORPORATION ]
