R&S SMA100B - Page 157

Avionic standards
R&S
®
SMA100B
157User Manual 1178.3834.02 ─ 09
The RMS modulation depth of the sum signal depends on the phase setting of both
modulation tones.
The "Sum of Depth" and "COM/ID > Depth" must be smaller than 100 %.
Remote command:
[:SOURce<hw>]:ILS:LOCalizer:SDM on page 620
DDM - SDM Coupling
Selects if the DDM value is fixed or is changed with a change of sum of modulation
depths (SDM, see below).
"Fixed DDM"
The absolute DDM value stays constant, if the SDM is changed.
"Coupled to
SDM"
The absolute DDM value changes, if the SDM is changed. The DDM
value expressed in dB stays constant.
Remote command:
[:SOURce<hw>]:ILS:LOCalizer:DDM:COUPling on page 614
DDM Step
Selects the variation step of the DDM values.
"Decimal"
Decimal variation according to the current cursor position.
"Predifined"
Variation in predefined steps according to the standardized DDM val-
ues.
Remote command:
[:SOURce<hw>]:ILS:LOCalizer:DDM:STEP on page 616
DDM Current
Sets the current of the ILS indicating instrument corresponding to the DDM value. The
instrument current is calculated according to:
DDM µA = DDM × 967.75 µA
A variation of the instrument current automatically leads to a variation of the DDM
value and the DDM value in dB.
Remote command:
[:SOURce<hw>]:ILS:LOCalizer:DDM:CURRent on page 614
DDM Depth
Sets the difference in depth of modulation (DDM) between the signal of the left lobe
(90 Hz) and the right lobe (150 Hz) of the ILS localizer modulation signal.
The DDM value in percent is calculated as follows:
●
"DDM Polarity > 90 Hz - 150 Hz" (default setting):
DDM = [ AM (90 Hz) - AM (150 Hz) ] / 100 %
●
"DDM 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:
[:SOURce<hw>]:ILS:LOCalizer:DDM[:DEPTh] on page 617
ILS configuration and settings