Introduction - If you have any usage issues, please Google them yourself
pulse shaping function:
Upsampling the data and Pulse-shaping.
Suitable for intergate number of upsampling_rate.
psflt_data has the same length with that of data times upsampling_rate.
if the length of pulse_filter is 2*grp_delay*upsampling_rate+1
By Aijun Song, July, 2005