Why do I receive artifacts, associated with finite frequency grid and aperiodic input signals, that lead to wrong answers in BER plots when using the RF Blockset 1.3.1 (R2006b)?

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MathWorks Support Team on 27 Jun 2009

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When I run my model that has a finite frequency grid and aperiodic input signals, the resultant BER (Bit Error Rate) plot is wrong.

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Answer 1

MathWorks Support Team on 27 Jun 2009

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This enhancement has been incorporated in Release 2008a (R2008a). For previous product releases, read below for any possible workarounds:

This is a limitation in the RF Blockset, which is unable to accurately represent a pseudo-aperiodic signal in the frequency domain, as it requires an infinitely fine frequency grid, and an infinitely long FIR filter.

To work around this issue, you can try to set the FIR filter length to be several symbols long, and to increase ntaps if the delay spread of the cascade is greater than or on the order of ntaps*t_s.