Circuit Description - Sony BDX-N1000 Maintenance Manual

1-7. Circuit Description

1-7. Circuit Description
Outline
The BDX-N1000 that is the MPEG2 network interface unit, is the equipment to realize the "MPEG over
ATM."
1)
The BDX-N1000 has the two functions: one is to convert the MPEG TS to the ATM cell and to send out
the converted data, while the other function is to receive the ATM cell and to reconstruct the TS.
2) 3)
Transmission and reception of the ATM are possible in both modes of AAL1 and AAL5 .
The TS supports both of the 188 byte input and the 204 byte input. (However, the AAL5 mode supports
only the 188 byte input.)
The BDX-N1000 can support various ATM transmission lines by replacing the optional boards (BDKP-
N1001, BDKP-N1002, BDKP-N1003 and BDKP-N1004).
4)
The BDX-N1000 itself can only support the PVC .
ATM transmission block
The ATM transmission block divides TS and converts the divided TS to the ATM cells.
The ATM transmission block supports both the AAL1 and AAL5 modes.
5)
In the AAL1 mode, the FEC code for error correction is added as the measure for the data error during
transmission.
The ATM cells are transmitted on the network at the previously-contracted rate.
6)
In addition, there is a mode in which the TS PCR jitter that is caused by delay of the ATM cells can be
removed.
ATM reception block
The ATM reception block reconstructs the ATM cells and converts them to the TS cell.
The ATM reception block supports both the AAL1 and AAL5 modes.
The data errors that have occurred during transmission are corrected using the FEC code, in the AAL1
mode.
The TS is output at the rate according to the ATM cell rate.
In addition, the ATM reception block contains the mode in which the TS PCR jitter that is caused by the
delay of the ATM cells can be removed.
CPU block
The CPU block establishes the setups using the commands that the CPU block receives from the RS-
232C connector or from the 10 BASE-T connector. The CPU block also displays the various errors on the
dot matrix display and by the LED on the front panel, and also outputs the errors to the alarm output
connector on the rear panel to notify the error to external devices.
In addition, the CPU block has the signaling function in order to realize the IP packet communication (IP
over ATM) and its services through the ATM line. (Its software is optional.)
1) TS : Transport Stream
2) AAL1: ATM Adaptation Layer 1
3) AAL5 : ATM Adaptation Layer 5
4) PVC : Permanent Virtual Connection
5) FEC : Forward Error Correction
6) PCR : Program Clock Reference
1-13 (E)
BDX-N1000