RCVDL56DPFL/SP, RCV56DPFL/SP, and RCV336DPFL/SP Designer’s Guide
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2.2 LINE TRANSFORMER REQUIREMENTS FOR V.34/V.32
K56flex/V.34/V.32 bis/V.32 places high requirements upon the Data Access Arrangement (DAA) to the telephone line. Any
non-linear distortion generated by the DAA in the transmit direction cannot be canceled by the MDP's echo canceller and
interferes with data reception. The designer must, therefore, ensure that the total harmonic distortion seen at the RXA input
to the MDP be at least 45 dB (RC336DPFL) or 65 dB (RC56DPFL) below the minimum level of received signal. Due to the
wider bandwidth requirements in K56flex and V.34, the DAA must maintain linearity from 10 Hz to 3954 Hz (RC336DPFL) or
4000 Hz (RC56DPFL).
Note that the major source of non-linear distortion in a DAA is the line transformer. A suitable line transformer is the
MIDCOM 671-8262 or equivalent.
When designing a DAA, the designer should take into account a worst case subscriber line, giving very poor matching to the
DAA hybrid circuit and resulting in a large near-end echo.
Summary of Contents for RC336DPFL
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