MATLAB: How does the function RCOSFIR in Communications Toolbox 3.4 (R2006b) behave when the second argument N_T is specified as a scalar instead of a vector of length 2

Communications Toolbox

The documentation for the RCOSFIR function in the Communications Toolbox specifies that the second argument N_T is required to be a vector of length 2 indicating the number of symbol periods before and after the peak response. However, this function does not give an error if the argument N_T is specified as a scalar. What is it doing in this case, and is the result incorrect?

Best Answer

This bug has been fixed in Release 2007b (R2007b). For previous product releases, read below for any possible workarounds:
The following section is missing from the documentation of the RCOSFIR function in Communications Toolbox.
The parameter N_T can be either a scalar or a vector of length 2. If N_T is specified as a scalar, then the filter length is 2 * N_T + 1 input samples. If N_T is a vector, it specifies the extent of the filter. In this case, the filter length is N_T(2) - N_T(1) + 1 input samples (or (N_T(2) - N_T(1))* RATE + 1 output samples).
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