Real Time

Filter Setup Dialog Box

This topic explains the filter setup dialog box for the Filter (GSM) and Filter (EDGE) parameters. While both filters use the same selections and settings, the two filters are separate and independent of each other.

Use the following links to navigate to and view the various figures and available settings:

Filter Setup Figures		Tabs
	Selections and Tables		FIR
	Generate User FIR			FIR Tab Buttons
Selections					Insert
	Gaussian				Delete
	EDGE				Mirror
	User FIR Filter				Load Default
	User File				Generate
Buttons					Return
	Browse			FIR Tab Tables
	Insert				User Filter Setting
	Export				Default Filter Setting
	Clear		Plot h(t)
			Plot FFT

Filter Setup Figures

Selections and Tables

Generate User FIR Filter using Default Filter Setting Table

Selections

Gaussian

Default setting for the Filter (GSM) parameter.

Selects a Gaussian filter and enables the Filter BbT setting.

GSM SCPI Command

EDGE SCPI Command

Filter BbT

Range: 0.100–1.000

Default: 0.300

Coupling: grayed out until Gaussian is the filter selection

Enter a value to set the BbT.

GSM SCPI Command

EDGE SCPI Command

EDGE

Default setting for the Filter (EDGE) parameter.

Selects a Laurant’s decomposition of a Gaussian filter with a 0.300 fixed BbT

GSM SCPI Command

EDGE SCPI Command

User FIR Filter

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

GSM SCPI Command — select PATTern from the command choices then use the GSM Pattern command to configure the filter pattern by setting the oversample ratio and filter coefficients

EDGE SCPI Command — select PATTern from the command choices then use the EDGE Pattern command to configure the filter pattern by setting the oversample ratio and filter coefficients

User File

Select this choice to load a predefined and saved FIR filter file. When selected, the Browse button becomes active.

GSM SCPI Command — select "<user FIR>" from the command choices

EDGE SCPI Command — select "<user FIR>" from the command choices

Buttons

Browse

Coupling: This button is enabled with the User File filter selection.

Click this button to open the Open user file dialog box to navigate to and select a previously configured and saved FIR filter file.

Import

Coupling: This button becomes visible with the User FIR Filter selection.

Use this button to load a previously defined and saved FIR filter configuration–launches the Open user defined data dialog box for navigation to a FIR filter file.

Export

Coupling: This button becomes visible with the User FIR Filter selection.

Use this button to save a defined FIR filter configuration–launches the Save user defined data dialog box for navigation to the desired location.

Clear

Coupling: This button becomes visible with the User FIR Filter selection.

This button clears the indexes and values leaving only Index 0 set to a value of zero.

Tabs

The tabs become visible with the User FIR Filter selection.

FIR

Provides the buttons and settings to configure the User FIR Filter:

FIR Tab Buttons

Insert	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. Index—The maximum number of indexes (coefficients) is 128 (Oversample Ratio x Length in Symbols). Value—Range: 0.000000 to 1.000000, use to set the coefficient value The maximum number of indexes is 128 (Oversample Ratio x Length in Symbols).
Delete	This button deletes the highlighted index.
Mirror	This button adds indexes (coefficients) by mirroring the current indexes.
Load Default	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.
Generate	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.
Return	This button appears after clicking the Load Default button. It returns to the User Filter Setting table without generating the coefficients.

FIR Tab Tables

The tables appear in the Filter Settings field.

User Filter Setting
Oversample Ratio Range: 1–4 Default: 4	This cell provides the oversample ratio (OSR) 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.
Length in Symbols	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.

Default Filter Setting	Click the Load Default button to view this table
Oversample Ratio Range: 1–4 Default: 4	This cell enables you to set the oversample ratio (OSR) value (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.
Filter Symbols Range: 1–32 Default: 8	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 128 coefficients (OSR x Filter Symbols). After generating the filter, the Filter Symbols value displays in the Length in Symbols cell of the User Filter Setting Table.
Filter Type Choices: RootNyquist \| Nyquist \| Gaussian \| Rectangle Default: RootNyquist	Click the cell and use the drop down arrow to display and select a filter.
Filter Alpha Range: 0.000–1.000 Default: 0.350	Available with the RootNyquist and Nyquist filter selections. With other filter selections, this setting is grayed out and displays N/A.
Filter BbT Range: 0.000–1.000 Default: 0.300	Available with the Gaussian filter selection. With other filter selections, this setting is grayed out and displays N/A.
Window Type Choices: None \| Hamming \| Hann \| Kaiser Default: None	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.
Beta Range: 1.000–10.000 Default: 4.000	This cell activates when you select the Kaiser windowing function. The default Beta factor provides a good solution for optimizing out-of-band performance (ACP), without seriously compromising passband performance (EVM). Changing the Beta factor adjusts the trade-off between ACP and EVM: Decreasing the value improves EVM. Increasing the value improves ACP.

Plot h(t)

Use this tab to view the Closed plot of the User FIR filter impulse response in time:

Plot FFT

Use this tab to view the Closed plot of the filter frequency response (calculated using a fast Fourier transform).