%% Design an FIR Interpolator
% To design an FIR Interpolator using the designMultirateFIR function, you must specify the interpolation factor of interest (usually greater than 1) and a decimation factor equal to 1. You can use the default half-polyphase length of 12 and the default stopband attenuation of 80 dB. Alternately, you can also specify the half-polyphase length and stopband attenuation values.
% Design an FIR interpolator with interpolation factor set to 5. Use the default half-polyphase length of 12 and the default stopband attenuation of 80 dB.

b = designMultirateFIR(5,1);
fvtool(b,'impulse')

% Copyright 2012 The MathWorks, Inc.