| Communications Toolbox | |
If rcosflt designs the filter automatically, then you can control the rolloff factor of the filter, as described below. If you specify your own filter, then rcosflt does not need to know its rolloff factor.
The rolloff factor determines the excess bandwidth of the filter. For example, a rolloff factor of .5 means that the bandwidth of the filter is 1.5 times the input sampling frequency, Fd. This also means that the transition band of the filter extends from .5 * Fd to 1.5 * Fd.
The default rolloff factor is .5, but if you want to use a value of .2, then you can use a command such as the one below. Typical values for the rolloff factor are between .2 and .5.
y = rcosflt([1;0;0],1,8,'fir',.2); % Rolloff factor is .2.
| | Specifying Filters Using Input Arguments | Controlling the Group Delay | |
© 1994-2005 The MathWorks, Inc.