N5161A/62A/81A/82A/83A MXG Signal Generators User's Guide

Basic Digital Operation (Option 651/652/654)Using Finite Impulse Response (FIR) Filters in the Dual ARB Real-Time Modulation FilterUsing Finite Impulse Response (FIR) Filters in the Dual ARB Real-Time ModulationFilterFinite Impulse Response filters can be used to compress single carrier I/Q waveforms down to justthe I/Q constellation points and then define the transitions similar to the modulation filter in ArbCustom (refer to “Using Finite Impulse Response (FIR) Filters in ARB Custom Modulation” onpage 279). The key difference for dual ARB real- time modulation is that a filter is applied as thewaveform plays, rather than in the waveform data itself.Figure 8-17 Filter MenuMode > Dual ARB > Arb Setup > More > Real-Time Modulation Filter >Enables or disables the Modulation Filter. This filter is typically applied to an Arb Waveformcontaining just the I/Q symbol decision points. The Modulation Filter then effectivelydefines the transitions between the symbol decision points. This means that the filter musthave an oversample ratio of 2 or more. When this feature is active, the Sample Clock Rateis actually the Symbol Rate. Also, the filter must be real (refer to page 217).Available only when the filter selected =Root Nyquist or Nyquistpage 208This softkey changes, dependingon the selected filter–type.Opens the IS–95filter selectionmenu.page 213page 205Available only when thefilter selected = GaussianFor details on each key, use key help as described on page 42.Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide 207