The "ILS-GS Modulation" dialog is opened in the "Mod" function block or using the MENU key under "Mod".
In the upper section, the modulation source is selected and the modulation switched on. The configuration of the selected external and/or internal modulation source is performed in the lower section of the dialog.
Activates ILS-GS modulation.
Activation of ILS-GS modulation deactivates AM, VOR, ILS-LOC, Marker Beacon and ADF modulation.
Source selection and the associated parameters are disabled in the "LF Generator / Output" dialog:

Defines the polarity for DDM calculation (see DDM Depth).
Remote command:Enters the arithmetic sum of the modulation depths of the upper lobe (90Hz) and lower lobe (150Hz) ILS-GS signal contents. The RMS modulation depth of the sum signal depends on the phase setting of both modulation tones. The sum of Sum of Depth and COM/ID depth must be smaller than 100 PCT.
Remote command:Selects the simulation mode for the ILS-GS modulation signal. A change of the setting automatically changes the sign of the DDM value.
This setting simulates the direction in which the pilot has to correct the course.
"Up" | The 150-Hz modulation signal is predominant, the DDM value is negative(the airplane is too low, it must climb). |
"Down" | The 90-Hz modulation signal is predominant, the DDM value is positive (the airplane is too high, it must descend). |
Enters the current of the ILS indicating instrument corresponding to the DDM value. the instrument current is calculated according to:
DDM uA = DDM × 857,125 uA
A variation of the instrument current automatically leads to a variation of the DDM value and the DDM value in dB.
Remote command:Enters the difference in depth of modulation between the upper lobe (90Hz) and the lower lobe (150Hz) tone of the ILS-GS modulation signal.
- Polarity 90 Hz - 150 Hz (default setting):
DDM = [ AM(90 Hz) - AM (150 Hz) ] / 100% - Polarity 150 Hz - 90 Hz:
DDM = [ AM(150 Hz) - AM (90 Hz) ] / 100%
A variation of the DDM value automatically leads to a variation of the value of the instrument current and the DDM value in dB.
Remote command:Enters the DDM value in dB. The dB value is calculated according to:
DDM dB = 20 × LOG [(SDM+DDM×100%) / (SDM-DDM×100%)]
A variation of the value automatically leads to a variation of the DDM value and the instrument current.
Remote command:Enters the difference in depth of modulation between the upper lobe (90Hz) and the lower lobe (150Hz) tone of the ILS-GS modulation signal.
- Polarity 90 Hz - 150 Hz (default setting):
DDM = [ AM(90 Hz) - AM (150 Hz) ] - Polarity 150 Hz - 90 Hz:
DDM = [ AM(150 Hz) - AM (90 Hz) ]
A variation of the DDM value automatically leads to a variation of the value of the instrument current and the DDM value in dB.
Remote command:Selects if the DDM value is fixed or is changed with a change of sum of modulation depths (SDM, see below).
"Fixed" | The absolute DDM values stays constant when the SDM is changed. |
"SDM" | The absolute DDM values changes when the SDM is changed. The DDM value expressed in dB stays constant. |
Selects the operating mode for the ILS-GS modulation signal.
"Norm" | ILS-GS modulation is active. |
"90 Hz" | Amplitude modulation of the output signal with the upper lobe signal component (90Hz signal content) of the ILS-GS signal. The modulation depth of the 90-Hz signal results from the settings of parameters "Sum of depth (SDM)" and "DDM" according to:
|
"150 Hz" | Amplitude modulation of the output signal with the lower lobe signal component (150-Hzsignal content) of the ILS-GS signal. The modulation depth of the 150-Hz signal results from the settings of parameters "Sum of depth (SDM)" and "DDM" according to:
|
Enters the modulation frequency of the upper antenna lobe.
Remote command:Enters the modulation frequency of the lower antenna lobe .
Remote command:Enters the phase between the modulation signals of the upper and lower antenna lobe. The zero crossing of the lower lobe (150Hz) signal serves as a reference. The angle refers to the period of the signal of the lower antenna lobe.
Remote command:Activates the ILS-GS default setting.
Parameter | Value |
---|---|
State | Off |
Sum of Depth | 80 Percent |
Fly | Up |
DDM | 0 |
Mode | Norm |
Up Frequency | 90 Hz |
Down Frequency | 150 Hz |
Up/Down Phase | 0 deg |
COM/ID State | Off |
COM/ID Frequency | 1020 kHz |
COM/ID Depth | 10 percent |
Selects the variation of the DDM values via the rotary knob.
"Decimal" | Decimal variation according to the current cursor position. |
"Defined" | Variation in predefined steps according to the standardized DDM values:
|
n.a.
Selects the variation of the carrier frequency via the rotary knob.
Selects the ICAO channel, i.e., the ILS-GS transmitting frequency. The RF-frequency is set to the value selected here. A variation of the carrier frequency by the rotary knob is performed in predefined steps according to the standardized ILS-GS transmitting frequencies (see table). The ICAO channel settings for ILS-GS and ILS-LOC are coupled.
Remote command:Changes to ILS-LOC modulation and opens the menu. The current state of the ILS GS modulation (On or Off) is also set for ILS-LOC. The RF frequency setting automatically changes to the transmitting frequency associated with the set ICAO channel for ILS-LOC if the state is on. .
Remote command:n.a.
Switching on/off an external modulation. The external signal is input via the AM EXT connector.
"Off" | Selects the internal modulation source for ILS-GS modulation. |
"EXT (MOD AM)" | Selects the external source. The external signal is added to the internal signal. Switching off the internal source is not possible. The external signal is input via the AM EXT connector. The sensitivity is 10 mV per percent modulation depth.
Note: There can be an overmodulation as a function of the level of the external signal without a corresponding caution message being generated.In order to avoid an overmodulation, the peak value of the external signal is to be delimited corresponding to the sum of the modulation depths of the remaining ILS signal components. |
Imprint | Statement of Privacy | Terms & Conditions | © 2016 ROHDE & SCHWARZ |