Distinguishing between 100G hard decision and soft decision NS4 boards

The hard decision of a short-distance transmission board covers all OTM sites on a ring.
Compared with a hard decision board, a soft decision board has higher decision margin, supports longer transmission distance, and tolerates a higher BER.
How can I identify 100G hard decision and soft decision NS4 boards?
1. BOM: 03030SSE, finished board, Optix OSN 8800-TN57NS4T01, 100 Gbit/s line service processing board, (LH, HFEC, Coherent, Tunable, 50 GHz, LC)
//Boards containing HFEC are hard decision boards.
03030YUB finished board, Optix OSN 8800-TN57NS4T61, 100 Gbit/s line board (ULH, SDFEC2, wDCM, Coherent, Tunable, 50 GHz, LC)
// Boards containing SDFEC2 are soft decision boards that support longer transmission distance and tolerate higher BERs.
2. NMS:
On the U2000, click an NS4 board for WDM query. If a board contains HFEC, it is a hard decision board. If a board contains SDFEC2, it is a soft decision board.
In a DWDM system, because of various factors, some bit errors (the ratio of bit errors to the received bits is called bit error ratio or BER) are generated at the receive end after the O/E conversion. As a result, the electrical signal recovered by the receiver is not satisfactory. FEC was therefore introduced to DWDM systems. To correct bit errors, an FEC encoder is used at the transmit end and an FEC decoder is used at the receive end. This helps reduce the BER at the receive end.
Extra overhead is introduced when the FEC encoder/decoder encodes/decodes the raw data. The percentage of the FEC overhead to the raw data is called FEC overhead percentage.
The FEC type used by hard-decision boards is HD-FEC, and the FEC overhead percentage is 7%. The HD-FEC decoder receives with only one bit (1 or 0) of information and no other additional information. Therefore, its output is quantized to two levels, namely �?�?and �?�?
The FEC type used by soft-decision boards is SD-FEC, and the FEC overhead percentage is 20%. Different from the HD-FEC decoder, the SD-FEC decoder receives additional data to indicate the reliability of a decision. Samples are classified as a "strong 0", a "weak 0", a "weak 1", and a "strong 1".
The difference between HD-FEC and SD-FEC lies in the data sent to the decoder. As the FEC overhead percentage increasing, the coding gain increases more slowly. As the FEC overhead percentage increasing, SD-FEC will see smaller increases in its NCG compared to HD-FEC, and even no increase in the NCG.
Compared with hard-decision boards, soft-decision boards have larger decision thresholds, support longer transmission distances, and tolerate higher BERs.

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