370 Keysight EXG and MXG X-Series Signal Generators User’s Guide
Using Avionics VOR/ILS Softkeys for N5171B/72B and N5181B/82B with Option 302
Using ILS Localizer Softkeys
Example:
To correct if the right signal at 150 Hz is stronger at 0.2 DDM,
the aircraft would have to be pointed Left
(:AVIonics:ILSLocalizer:FLY:DIRection LEFT)
with a DDM of 0.2
(:AVIonics:ILSLocalizer:DDM 0.2)
To set the ILS Localizer DDM value
1. Press Aux Fctn > Avionics > ILS Localizer
2. Press DDM/SDM
3. Press DDM
(Default <value> is 0.0000.)
4. Select a <value> from -0.99 to 0.99 and press Enter.
Since: (-SDM/100) - (SDM/100) and SDM can be from 0% to 99%, DDM can
have a range from: -0.99 to 0.99
These softkeys set a value for the “Difference in Depth of Modulation” (DDM).
The primary mechanism which makes it possible for a pilot to obtain guidance
to a runway is the aircraft receiver's ability to detect the “Difference in Depth of
Modulation (DDM)” between this 90 Hz AM and 150 Hz AM modulation.
DDM is defined to be the “percentage modulation depth of the larger signal”
minus the “percentage modulation depth of the smaller signal”,
divided by 100.
DDM = [AM(90 Hz)% - AM(150 Hz)%] / 100
To set the ILS Localizer DDM value in micro-amps (uA)
1. Press Aux Fctn > Avionics > ILS Localizer
2. Press DDM/SDM
3. Press DDM uA
(Default <value> is 0.0 uA.)
4. Select a <value> from 0 to 10.0 uA and press Enter.
These softkeys set a value for the difference in depth of modulation (DDM)
in uA.