Keysight EXG and MXG X-Series Signal Generators User’s Guide 137Avionics VOR/ILS (Option 302)Using ILS Localizer Softkeys4. Enter a value that is within the range of the current SDM value.Typically the SDM default value provides sufficient range for mostapplications.If SDM is set to 99%, then the full range (–958.1 to 958.1 μA) of DDM uA isavailable. The following demonstrates the limits of DDM uA’s range:((–SDM/100)*(150/.155)) to ((SDM/100)*(150/.155))As SDM’s value increases or decrease, so does the range.The DDM uA default value is 0.0 uA.To set the ILS Localizer DDM value as a percentage (%)This process sets a value for the difference in depth of modulation (DDM)in %. DDM can be expressed either in terms of percentage (%) or as amodulation index. A DDM of 1% is equivalent to 0.01 DDM.1. Press Aux Fctn > Avionics > ILS Localizer2. Press DDM/SDM3. Press DDM%(Default value is 0.00%.)4. Enter a value within the range of the current SDM value.Typically the SDM default value provides sufficient range (–40% to 40%)for most applications.If SDM is set to 99%, then the full range (-99% to 99%) of DDM isavailable. The following demonstrates the limits of DDM’s range:(-SDM) to (SDM)As SDM’s value increases or decrease, so does DDM’s range.To set the ILS Localizer SDM valueThis process sets the sum of depth of modulation (SDM):1. Press Aux Fctn > Avionics > ILS Localizer2. Press DDM/SDM3. Press SDM(Default value is 40.00%.)4. Select a value from 0 to 99% and press Enter.The SDM range is defined by the following equation:SDM = [AM(90 Hz) + AM(150 Hz)] / 100:
