DT Etherlink IV User Manual- 35 -Figure 3.20 G.826 performance evaluationOn the E1 side, four CRC4 check bits are generated per sub-multiframe (SMF) and compared withthe corresponding bits of the next SMF. If they do not match, the CRC4 error counter isincremented.On the SHDSL side, six CRC6 check bits are generated per SHDSL frame. CRC6 errors are usedby the software to count the block errors of the SHDSL channel and to evaluate its errorperformance according to ITU-T Rec. G.826.For the E1 interface, calculations according to G.826 are only possible in the framed modeaccording to G.704 with the CRC4 option enabled. In the framed mode with the CRC4 optiondisabled, only FAS errors are detected.The estimation of a bit error rate is not within the scope of G.826 calculations.3.2.5 BERT TestWe suggest BERT testing in the following way: Switch on Loop2 on the remote unit (slave) andsetup the BERT on the master unit.Figure 3.21. BERT setup ExampleConfiguration Example:CO_BERT>CONF--------------------------------------------------------------------------------Current BERT configuration:--------------------------------------------------------------------------------Interface : E1-1, Internal (to SHDSL1)Pattern : 2E7TX Slots : [00-15] PG PG PG PG PG PG PG PG PG PG PG PG PG PG PG PG: [16-31] PG PG PG PG PG PG PG PG PG PG PG PG PG PG PG PGRX Slots : [00-15] BT BT BT BT BT BT BT BT BT BT BT BT BT BT BT BT: [16-31] BT BT BT BT BT BT BT BT BT BT BT BT BT BT BT BT--------------------------------------------------------------------------------CO_BERT>GeneratorReceiverGeneratorReceiverGeneratorReceiverCRC6CRC4CRC4CRC4CRC6 FEBEG.826CountersReceiverGeneratorReceiverGeneratorReceiverGeneratorCRC6 CRC4CRC4CRC4CRC6 FEBEG.826CountersSHDSLSLAVE MASTERE1E1E1E1TXRXTXRX TXRXTXRXMaster Regenerator SlaveE1 Interface1LOOP 2 1:RBERT activated Loop2 activated
