- Agilent Signal Generator User's Guide

150 Chpater 6

Custom Arb Waveform Generator

Working with Filters

To Create a User-Defined FIR Filter with the FIR Values Editor

In this procedure, you use the FIR Values editor to create and store an 8- symbol, windowed, sinc

function filter with an oversample ratio of 4. The Oversample Ratio (OSR) is the number of filter

coefficients per symbol.

You can define from 1 to 32 FIR coefficients, where the maximum combination of symbols and

oversample ratio is 1024 coefficients.

The FIR Values editor allows a maximum filter length of 1024 coefficients, but the PSG hardware is

limited to 512 symbols for arbitrary waveform generation, and 64 symbols for real- time waveform

generation. The number of symbols equals the number of coefficients divided by the oversample ratio.

If you enter more than the maximum number of symbols, the PSG cannot use the filter; it decimates

the filter (throws away coefficients) until the required condition is met and then uses the filter, but

fine resolution may be lost from the impulse response.

1. Press

Preset.

2. Press

Mode > Custom > Arb Waveform Generator > Digital Mod Define > Filter

Mode > Custom > Real Time I/Q Baseband > Filter

3. Press Define User FIR > More (1 of 2).

4. Press

Delete All Rows > Confirm Delete Of All Rows > More (2 of 2).

This brings up the FIR Values editor and clears the table of existing values.

5. Press

Edit Item.The Value field for coefficient 0 should be highlighted.

6. Use the numeric keypad to type the first value (−0.000076) from the following table and press

Enter. As you press the numeric keys, the numbers are displayed in the active entry area. (If you

make a mistake, you can correct it using the backspace key.) Continue entering the coefficient

values from the table until all 16 values have been entered.