A frequency response defined by an external point data file.
| 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.
For information on adjusting the bandwidth of the external filter file without editing the file, see Adjusting the Bandwidth. Note that changing the limit does not change the actual data within the file, so the original data is still intact. |
| 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. Note that changing the limit does not change the actual data within the file, so the original data is still intact. |
| 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. |
| Override Bandwidth Limits | When the Override Bandwidth Limits check box is checked, you have the ability to change the lower and upper limits frequency limits of the external filter. When a limit is set smaller than what is defined within the filter file, the response is "clipped" at that limit. When the limit is set larger than what is defined within the filter file, the response is "zero padded" to that limit. When the limits are changed, the Bandwidth field will update appropriately. When the Override Bandwidth Limits check box is not checked, the lower and upper limits will update to display the frequency limits as specified in the filter file. Again, the bandwidth field will update accordingly. |
| External Filename |
The name of the filter to use. For descriptions of valid keywords and values, see the External Filter Data File Format. |
| Reload | Reloads the original Upper and Lower Bandwidth limits from the external file. |
Adjusting the Bandwidth
The bandwidth of the external filter file can be easily adjusted without editing the file. By adjusting the Upper/Lower Bandwidth Limits you can easily change the bandwidth over which the filter is defined.
If the Upper/Lower Bandwidth Limits are reduced from what is defined in the file, the spectrum will be clipped. If the Upper/Lower Bandwidth Limits are set beyond what is defined in the file, the spectrum is zero padded.
Changing the Upper/Lower Bandwidth Limits does not change the actual data within the file, so the original data is still intact. The original file limits can be reloaded by using the Reload button. The Reload button will reload the file and remove any customizations made to the Upper and Lower Bandwidth Limits.