ISO-CMOS
MT8950
125
µs
Internal
Clock
0
b7
-1
#
1
1
2
1
3
1
4
b
4
b
3
b
2
b
1
b
0
1
5
1
6
1
7
b
1
b
0
b
4
b
3
b
2
b
1
b
0
b
4
b
3
b
2
1
0
0
1
1
1
0
b
4
b
3
b
2
b
1
b
0
0
b
4
b
3
b
2
b
1
b
0
1
b
4
b
3
b
2
b
1
b
0
=11111
1
2
3
4
5
6
7
8
9
10
•••
22 23 24 25 26 27 28 29 30 31 0
b7
0
1
1
Frame Type
b6
1
1
b5
1
1
b
4
b
3
b
2
b
1
b
0
0
1
1
1
0
0
1
0
1
2
3
4
0
1
2
3
4
5
6
7
Figure 3 - TEM Coding Scheme
(Note: Waveforms shown are bipolar RZ equivalent of separate RZ/NRZ inputs)
#
1
2
3
4
5
6
7
Frame
Description
No Pulse
2 Data Pulses (T=52 µs)
3 Data Pulses (T=52 µs)
1 Data Pulse
Violation Pulse
2 Data Pulses (T=104 µs)
(Timeslot 4 to 31)
2 Data Pulses (T=104 µs)
(Timeslot 0 to 3)
Level
†
b7
1/0
1/0
1/0
1/0
1/0
1/0
1/0
Frame Type
b6 b5
1
1
1
1
1
0
0
1
1
1
0
0
1
0
First Transition
b4 b3 b2 b1 b0
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
Y Y Y X X
Notes
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)
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
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.
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
6-7
MITEL [ MITEL NETWORKS CORPORATION ]
