Raised Cosine Model
The raised-cosine filter is an implementation of a low-pass Nyquist Filter; i.e., one that has the property of vestigial symmetry. This means that its spectrum exhibits odd symmetry about
where 
is the symbol period of the communications system (inverse of the Symbol rate).
| Parameter | Description |
|---|---|
| Upper Bandwidth Limit | The filter’s upper limit on the power spectrum. The bandwidth limit is relative to the carrier frequency (the carrier being at zero Hz), and is specified as a positive value. The upper limit is considered to be a sharp cutoff point and the spectrum is zero beyond the limit. |
| Lower Bandwidth Limit | The filter’s lower limit on the power spectrum. The bandwidth limit is relative to the carrier frequency and is specified as a negative value. The lower limit is considered to be a sharp cutoff point and the spectrum is zero beyond the limit. |
| Bandwidth | A read-only field equal to the difference between Upper Bandwidth Limit and Lower Bandwidth Limit. It is the total spectral bandwidth over which the filter has a defined response. The filter will only compute over frequencies that are in its defined response; outside its defined response, complete attenuation occurs. |
| Insertion Loss | A fixed signal attenuation with the spectrum loss computed by the filter’s response characteristics. |
| Roll-off Factor | A measure of excess bandwidth of the filter and smoothness of the filter characteristic response. Roll-off factor of zero (0 %) makes it a rectangular filter, while a factor of 1 (100 %) makes it a cosine filter. |
| Symbol Rate | The inverse of the symbol period of the data stream. |
See Proakis, J., Digital Communications, 3rd ed., McGraw-Hill Inc. (1995).