Product Manual - DM991 Series V Family - 204.4092.08
71
1
2
3
4
5
6
7
8
Si
0
0
1
1
0
1
1
Note 1
Si
1
A
S
a4
S
a5
S
a6
S
a7
S
a8
Note 1 Note 2 Note 3
Alterned frames
Bit number
Frame containing the Frame
Alignment Signal
Frame alignment signal
2) Bit always set on 1.
3)Remote alarm indication. If operation normal, set on 0, in alarm set on 1. In case the converter
receptor loses frame synch this bit is transmitted in 1.
4) For specific uses: Bits usually set on 1.
Frame wthout FAS
Note 4
Notes:
1) Si – bit reserved for international use. Usually set to 1 except when CRC4 is used as will be seen.
Table 19. Multiframe structure
Besides this basic multiframe, which is always present, there may be other types of multiframe that are
completely independent among them, and superimposed over the basic multiframe:
16.1.1. CRC4 Multiframe
Made up by 16 frames and uses Si bit of timeslot 0 of the frames to perform the Cyclic Redundancy
Check-4 procedure, making it possible to evaluate transmission quality. This multiframe always starts at a
frame that has FAS. The multiframe structure is identified by a six-bit structure known as the CRC4
multiframe alignment signal, found on odd frames. On the last two odd frames, sub multiframe error
signals are transmitted. Bit E of frame 13 (E13) corresponds to the error occurred on sub-multiframe I and
E15 correspond to the error occurred on sub-frame II. On the even frames, which have FAS present, the
four CRC bits calculated from the previous sub-frame are transmitted. Table 20, shows the CRC4
multiframe structure.
Summary of Contents for DM991C
Page 1: ...DM991 SERIES V DM991C DM991CE DM991S DM991SE PRODUCT MANUAL 204 4092 08 rev 08 Date 8 12 2008 ...
Page 66: ...Product Manual DM991 Series V Family 204 4092 08 66 Figure 31 LDL Test Converter Mode ...
Page 89: ...Phone 55 51 3358 0100 Support 55 51 3358 0122 Fax 55 51 3358 0101 www datacom ind br ...
