Instrument Function > Modulation > ILS-LOC Modulation > ILS-Localizer Modulation Settings
ILS-Localizer Modulation Settings

The "ILS-LOC 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.

State - ILS-LOC Modulation

Activates ILS-LOC modulation.

Activation of ILS-LOC modulation deactivates AM, VOR, ILS-GS, Marker Beacon and ADF modulation.

Source selection is disabled in the "LF Generator / Output" dialog:

Remote command: 
 
DDM Polarity- ILS-LOC Modulation

Defines the polarity for DDM calculation (see DDM Depth).

Remote command: 
 
Sum of Depth - ILS-LOC Modulation

Enters the arithmetic sum of the modulation depths of the left lobe (90Hz) and right lobe (150Hz) ILS-LOC 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: 
 
Fly - ILS-LOC Modulation

Selects the simulation mode for the ILS-LOC 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.

"Left"

The 150-Hz modulation signal is predominant, the DDM value is negative (the airplane is too far to the right, it must turn to the left).

"Right"

The 90-Hz modulation signal is predominant, the DDM value is positive (the airplane is too far to the left, it must turn to the right).

Remote command: 
 
DDM Current - ILS-LOC Modulation

Enters the current of the ILS indicating instrument corresponding to the DDM value. The instrument current is calculated according to:

DDM uA = DDM × 967.75 uA

A variation of the instrument current automatically leads to a variation of the DDM value and the DDM value in dB.

Remote command: 
 
DDM Depth - ILS-LOC Modulation

Enters the difference in depth of modulation between the signal of the left lobe (90 Hz) and the right lobe (150 Hz).

The DDM value is calculated to formula:
  • 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 DDM value in dB and the value of the instrument current.

Remote command: 
 
DDM Logarithmic - ILS-LOC Modulation

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: 
 
DDM Percent - ILS-LOC Modulation

Enters the difference in depth of modulation between the signal of the left lobe (90 Hz) and the right lobe (150 Hz).

The DDM value in percent is calculated to formula:
  • 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 DDM value in dB and the value of the instrument current.

Remote command: 
 
DDM - SDM Coupling - ILS-LOC Modulation

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.

Remote command: 
 
Mode - ILS-LOC Modulation

Selects the operating mode for the ILS-LOC modulation signal.

"Norm"

ILS-LOC modulation is active.

"90 Hz"

Amplitude modulation of the output signal with the left lobe (90Hz) signal component of the ILS-LOC signal.

The modulation depth of the 90Hz signal results from the settings of parameters "Sum of depth (SDM)" and "DDM" according to:
  • parameter "Fly" = "Right"
    AM(90 Hz) = 0,5 × (SDM + DDM × 100%)
  • parameter "Fly" = "Left"
    AM(90 Hz) = 0,5 × (SDM - DDM × 100%)

"150 Hz"

Amplitude modulation of the output signal with the right lobe (150Hz) signal component of the ILS-LOC signal.

The modulation depth of the 150Hz signal results from the settings of parameters "Sum of depth (SDM)" and "DDM" according to:
  • parameter "Fly" = "Right"
    AM (150 Hz) = 0,5 × (SDM + DDM × 100%)
  • parameter "Fly" = "Left"
    AM (150 Hz) = 0,5 × (SDM - DDM × 100%)
Remote command: 
 
Left Frequency - ILS-LOC Modulation

Enters the modulation frequency of the antenna lobe arranged at the left viewed from the air plane.

Remote command: 
 
Right Frequency - ILS-LOC Modulation

Enters the modulation frequency of the antenna lobe arranged at the right viewed from the air plane.

Remote command: 
 
Left/Right Phase - ILS-LOC Modulation

Enters the phase between the modulation signals of the left and right antenna lobe. The zero crossing of the right lobe (150Hz) signal serves as a reference. The angle refers to the period of the signal of the right antenna lobe.

Remote command: 
 
Set to Default - ILS-LOC Modulation

Activates the ILS-LOC default setting.

Parameter

Value

State

Not affected by Set to default

Sum of Depth

40 Percent

Fly

Up

DDM

0

Mode

Norm

Left frequency

90 Hz

Right Frequency

150 Hz

Left/Right Phase

0 deg

COM/ID State

Off

COM/ID Frequency

1020 kHz

COM/ID Period

9 s

COM/ID Depth

10 percent

Remote command: 
 
COM/ID State - ILS-LOC Modulation

Switches on/off an additional communication/identification signal (COM/ID signal).

Remote command: 
 
Show Details - ILS-LOC Modulation

Reveals the detailed setting options for the COM/Id signal. Once the details are revealed, the labeling on the button changes to "Hide Details". Use this to hide the detailed setting options display again. (COM/ID signal).

Remote command: 

n.a.

 
COM/ID Code - ILS-LOC Modulation

Enters the coding of the COM/ID signal by the international short name of the airport (e.g. MUC for the Munich airport). (COM/ID signal).

The COM/ID tone is sent according to the selected code (see table of Morse below).The length of the Morse code can be varied. For selection standard time scheme, the selected dot length determines the setting of all other length parameters of the Morse code (dash length, symbol space and letter space) . For selection user time scheme, all length parameters of the code can be set independently.

If no coding is entered, the COM/ID tone is sent uncoded (key down).

Morse Code

Letter

Morse Code

Letter

Morse Code

A

. -

N

- .

B

- . . .

O

- - -

C

- . - .

P

. - - .

D

- . .

Q

- - . -

E

.

R

. - .

F

. . - .

S

. . .

G

- - .

T

-

H

. . . .

U

. . -

I

. .

V

. . . -

J

. - - -

W

. - -

K

- . -

X

- . . -

L

. - . .

Y

- . - -

M

- -

Z

- - . .

Note:

The following values are default values:
  • A dot (.) has a tone duration of 100 ms
  • A dash (-) has a tone duration of 300ms
  • The time between two tones is 100ms
  • The time between two letters is 300ms
After each word a word space is entered. The word repetition rate is 7 words/minute. As the word length can vary between 900 ms and 4500 ms the word space between the words varies accordingly.

Example: 

ID code = MUC

The word length = 300+100+300+300+100+100+100+100+300+300+300+100+100+100+300+100+100 = 3100 ms

Remote command: 
 
COM/ID Frequency - ILS-LOC Modulation

Enters the frequency of the COM/ID signals.

Remote command: 
 
COM/ID Period - ILS-LOC Modulation

Enters the period of the COM/ID signal in seconds.

Remote command: 
 
COM/ID Depth - ILS-LOC Modulation

Enters the AM modulation depth of the COM/ID signal. The sum of subcarrier depth, VAR depth and COM/ID depth must be smaller than 100 PCT.

Remote command: 
 
COM/ID Time Schema - ILS-LOC Modulation

Selects if the set dot length determines the dash length (= three times the dot length) (setting Standard) or if all length parameters can be set independently (setting User). (COM/ID signal).

Remote command: 
 
COM/ID Dot Length - ILS-LOC Modulation

Enters the length of a Morse dot by means of seconds. The length of the dash (3xdot), space (=dot) and letter space (=3xdot) is also determined by this entry if time scheme standard is selected.

Remote command: 
 
COM/ID Dash Length - ILS-LOC Modulation

(user time schema only)

Enters the length of a Morse dash by means of seconds.

Remote command: 
 
COM/ID Symbol Space - ILS-LOC Modulation

(user time schema only)

Enters the length of a symbol space by means of seconds.

Remote command: 
 
COM/ID Letter Space - ILS-LOC Modulation

(user time schema only)

Enters the length of a letter space by means of seconds.

Remote command: 
 
DDM Knob Step - ILS-LOC Modulation

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:
  • -0,2000
  • -0.1550 (Course Sector)
  • -0,0930, -0,0460
  • 0,0000 (Course Line)
  • +0,0460, +0,0930
  • +0,1550 (Course Sector)
  • +0,2000
Remote command: 

n.a.

 
Carrier Frequency Step - ILS-LOC Modulation

Selects the variation of the carrier frequency via the rotary knob.

"Decimal"

Decimal variation according to the current cursor position.

"ICAO"

Activates variation in predefined steps according to the standardized ILS-GS transmitting frequencies (see table, values in MHz). The start value can be selected in the field "ICAO Channel" below.

The selection is effective on both ILS modulations. A change to modulation ILS-GS automatically causes the RF frequency to be adapted to the glide slope value which is coupled to the localizer setting (see table).

The individual values in the table are:
  • Ch. No. = ICAO channel number
  • LOC Freq. = ILS Localizer transmitting frequency (MHz)
  • GS Freq. = ILS GS frequency (MHz)
Standardized ILS-GS and ILS-LOC transmitting frequencies (MHz) and the associated ICAO channels

Ch. No.

LOC Freq.

GS Freq.

 

Ch. No.

LOC Freq.

GS Freq.

 

Ch. No.

LOC Freq.

GS Freq.

18X

18Y

108.10

108.15

334.70

334.55

 

32X

32Y

109.50

109.55

332.60

332.45

 

46X

46Y

110.90

110.95

330.80

330.65

20X

20Y

108.30

108.35

334.10

333.95

 

34X

34Y

109.70

109.75

333.20

333.05

 

48X

48Y

111.10

111.15

331.70

331.55

22X

22Y

108.50

108.55

329.90

329.75

 

36X

36Y

109.90

109.95

333.80

333.65

 

50X

50Y

111.30

111.35

332.30

332.15

24X

24Y

108.70

108.75

330.50

330.35

 

38X

38Y

110.10

110.15

334.40

334.25

 

52X

52Y

111.50

111.55

332.90

332.75

26X

26Y

108.90

108.95

329.30

329.15

 

40X

40Y

110.30

110.35

335.00

334.85

 

54X

54Y

111.70

111.75

333.50

333.35

28X

28Y

109.10

109.15

331.40

331.25

 

42X

42Y

110.50

110.55

329.60

329.45

 

56X

56Y

111.90

111.95

331.10

330.95

30X

30Y

109.30

109.35

332.00

331.85

 

44X

44Y

110.70

110.75

330.20

330.05

    
Remote command: 
 
ICAO Channel - ILS-LOC Modulation

Selects the ICAO channel, i.e., the ILS-LOC 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-LOC transmitting frequencies (see table). The ICAO channel settings for ILS-GS and ILS-LOC are coupled.

Remote command: 
 
Change to ILS-GS - ILS-LOC Modulation

Changes to ILS-GS modulation and opens the menu. The state of the ILS LOC modulation (On or Off) is also set for ILS-GS. The RF frequency setting automatically changes to the transmitting frequency associated with the set ICAO channel for ILS-GS if the state is on.

Remote command: 

n.a.

 
EXT AM - ILS-LOC Modulation

Switching on/off an external modulation. The external signal is input via the AM EXT connector.

"Off"

Selects the internal modulation source for ILS-LOC 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.

Remote command: 
 

 


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