Upstream Power Back Off (UPBO) The Problem is: Upstream bit rates on long loops are dramatically reduced. Very high-speed digital subscriber line (VDSL) upstream data transmission in a distributed environment suffer from relatively strong far-end crosstalk generated by the shorter lines in the binder. very low Bit rate up normal very high The Solution is: UPBO. To secure the capacity on lines of all lengths, the transmit power of shorter lines should be reduced. This power reduction is known as upstream power back off or UPBO. normal Bit rate up normal ELQ 30A+ Universal Copper Qualifier provides templates for the qualification of local cables when UPBO is applied. ELEKTR NIKA

UPBO versus Loop Length The amount of UPBO changes with the location of customer modems. The reduction is maximal in short loops, and minimal in long loops. ~900 m ~600 m ~300 m The calculation of applicable UPBO is based on the ”Electrical Length” of loops. The definition of Electrical Length = Loss at 1 MHz ELQ 30A+ Universal Copper Qualifier provides achievable upstream data rate calculations with and without UPBO ELEKTR NIKA

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