Filter Setup

Tabs

FIR

Plot h(t)

Plot FFT

This filter that meets the criteria of the IS-95 standard.

This filter is a combination of the IS-95 filter (above) and the equalizer filter described in the IS-95 standard and is best suited for IS-95 baseband filtering.

This filter meets the criteria of the IS-95 error function (for improved adjacent channel performance) with lower passband rejection than the filter specified in the IS-95 standard.

This filter is a combination of the equalizer filter described in the IS-95 standard and a filter that meets the criteria of the IS-95 error function (for improved adjacent channel performance), with lower passband rejection.

This is a GSM Gaussian filter with a fixed BbT value of 0.300.

Select this choice to expand the Filter Setup dialog box that provides tabs and additional buttons to configure a user FIR filter.

This button inserts a new index (coefficient) prior to the highlighted index. The value of the new index is copied from the highlighted index. After inserting a new index, change its value by highlighting it and entering a new value.

This button deletes the highlighted index.

This button adds indexes (coefficients) by mirroring the current indexes.

This button:

• replaces the User Filter Settings table with the Default Filter Setting table

• loads default settings into the Default Filter Settings table for the initial access during the current software session. If changes are made to the settings, subsequent Load Default button clicks loads the Default Filter Settings table with the modified settings.

This button appears after clicking the Load Default button and generates the filter coefficients using the settings from the Default Filter Setting table–coefficient indexes and values appear in the Index and Value columns of the tab. After the coefficient generation, the table changes back to the User Filter Setting table.

This cell provides the oversample ratio value (number of filter coefficients per symbol) applied to the FIR filter design. It uses two modes of operation:

• set the value by highlighting and entering a new value

• displays the oversampling ratio set in the Default Filter Setting table.

This cell only displays the number of symbols with a maximum of 32. Its value is derived from the Oversample Ratio value and the number of coefficients (index). This cell also displays the Filter Symbols value set in the Default Filter Setting table.

Click the Load Default button to view this table

This cell enables you to set the oversample ratio (number of filter coefficients per symbol) to be applied to the user FIR filter design. After generating the filter, the Oversample Ratio displays in the Oversample Ratio cell of the User Filter Setting Table.

Set the number of filter symbols.

This cell selects the number of symbols for the current FIR filter. The FIR table editor allows a maximum filter length of 512 coefficients with a maximum oversample ratio of 16 and a maximum of 32 symbols.

After generating the filter, the Filter Symbols value displays in the Length in Symbols cell of the User Filter Setting Table.

Click the cell and use the drop down arrow to display and select a filter.

Available with the RootNyquist and Nyquist filter selections. With other filter selections, this setting is grayed out and displays N/A.

Available with the Gaussian filter selection. With other filter selections, this setting is grayed out and displays N/A.

This cell accesses a menu for applying a windowing function to the selected filter. The default is to use no windowing (None), which optimizes the passband response (EVM). Several windowing selections are provided in this menu which can be applied to smooth the filter’s transition to zero. Windowing improves out of band performance (ACP) but simultaneously degrades EVM. With the Kaiser selection, the Beta cell is enabled for setting the windowing Beta.