peb2035 ETC-unknow, peb2035 Datasheet - Page 25

• Manufacturer Part Number: peb2035
• Description: Communications Advanced Cmos Frame Aligner
• Manufacturer: ETC-unknow

3
General Functions and Device Architecture
1. Receive Path
Receive Link Interface
For data input, two different data types with selectable input sense are supported:
Latching of data is done using the falling edges of the Receive Route Clock (RRCLK, 2048 kHz or
1544 kHz) recovered from the PCM receive data stream. Dual rail data is subsequently converted
into a single rail, unipolar bit stream. In PCM 30 mode, the HDB3 line code is used along with double
violation detection or extended code violation detection (selectable). In PCM 24 mode, a selection
between B8ZS or simple AMI (ZCS) coding is provided. In this case, all code violations that do not
correspond to zero substitution rules will be detected.
These errors increment the code violation counter (8 or 10 bits length).
Note: In PCM 30 mode, this counter can also be used to count sub-multiframe error indications
When using the unipolar input mode, the decoder is by-passed and no code violations will be
detected.
Additionally, the receive link interface comprises the alarm detection for AIS (Alarm Indication
Signal: unframed bit stream with constant logical 'one') and NOS (No Signal: input signal with an
insufficient bit rate or an insufficient density of ones).
The single rail bit stream is then processed by the receiver.
Receiver
For both the PCM 30 mode and the PCM 24 mode the following functions are performed:
If programmed and applicable to the selected multiframe format, CRC checking of the incoming
data stream is done by generating check bits for a CRC submultiframe (or ESF multiframe)
according to either the CRC 4 procedure (PCM 30, refer to CCITT Rec. G704) or the CRC 6
procedure (PCM 24, refer to CCITT Rec. G704). These bits are compared with those check bits that
Semiconductor Group
Dual rail data (PCM[+], PCM[–]) at ports RDIP, RDIM received from a line interface unit
(e.g. PEB 2235/PEB 2236, Siemens ISDN Primary Access Transceiver, IPAT).
Unipolar data at port ROID (PCM 30) or at port RDIP (PCM 24) received from a fibre optical
interface.
Synchronization on pulse frame
Synchronization on multiframe
Error indication when synchronization is lost. In this case, AIS is automatically sent to the system
side (this function can be disabled).
Initiating and controlling of resynchronization after reaching the asynchronous state. This may be
automatically done by the ACFA, or user controlled via the microprocessor interface.
Detection of remote alarm indication from the incoming data stream.
Separation of service bits and data link bits. This information is stored in special status registers.
Generation of control signals to synchronize the CRC checker, the parity generator, and the
receive speech memory write control unit.
instead of code violations.
Functional Description
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PEB 2035