PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 71

• Manufacturer Part Number: PEF2091
• Description: ICs for Communications(ISDN Echocancellation Circuit)
• Manufacturer: Siemens Semiconductor Group

PEB 2091
PEF 2091
Functional Description
Within one FSC-period, 32 bit up to 256 bit are transmitted, corresponding to
DCL-frequencies ranging from 512 kHz up to 4096 kHz.
®
Three optimized IOM
-2 timing modes exist for:
1)
Multiplexed Timing Mode
(LT and NT-PBX)
Plain Timing Mode (NT, NT-Auto Activation, COT-512, NT-RP and LT-RP)
Terminal Timing Mode (TE and COT1536)
All applications utilize the same basic frame and clocking structure, but differ in the
number and usage of the individual channels.
®
Figure 24
Basic Channel Structure of IOM
-2
Each frame consists of
• two 64 kbit/s channels B1 and B2
• the Monitor Channel for transferring maintenance information
• two bits for the 16 kbit/s D-channel
• four
command/indication
(C/I)
bits
for
controlling
of
layer-1
functions
(activation/deactivation and other control function) by i.e., layer-2 controller.
• two bits MR and MX for the handshake procedure in the Monitor Channel
3.6.1.1
Multiplexed Timing Mode
Note 9:
This section applies to the LT and the NT-PBX modes.
In multiplexed timing mode the IEC-Q supports bit rates from 256 kbit/s up to 2048 kbit/s
corresponding to DCL-frequencies from 512 kHz up to 4096 kHz.
®
The typical IOM
-2 line card or NT-PBX application comprises a DCL-frequency of 4096
kHz with a nominal bit rate of 2048 kbit/s. Therefore eight channels are available, each
consisting of the basic frame with a nominal data rate of 256 kbit/s. In LT mode the
downstream data (DD) are transferred on pin DIN, the upstream data (DU) on pin DOUT.
In NT-PBX mode the downstream data (DD) are transferred on pin DOUT, the upstream
1) This mode is also referred to as "Burst Mode"
Semiconductor Group
71
Data Sheet 01.99