Numeric Measurement Modes
R&S
®
EVSG1000
99
User Manual 1178.6227.02 ─ 06
Figure 4-16: Basics of the VOR phase angles (
Φ
) depending on the azimuth angle (
Θ
)
The frequency modulated secondary carrier for the reference phase is itself again
modulated in AM on the RF carrier of the VOR station. In addition to the signals neces-
sary for navigation, a Morse code with 1020
Hz can be transmitted on the VOR carrier.
Also, speech in the usual AF from 300
Hz to 3.3
kHz can be transmitted. Often the
voice channel of a VOR station is used for the transmission of ATIS (Automatic Termi-
nal Information Service) messages. The Morse code can be used to identify the VOR
station, similar to the
"Morse code identification signal"
on page 55 in the ILS signal.
The spectrum of a VOR signal is therefore composed of the carrier and three modula-
ted components.
Figure 4-17: Example of the VOR Spectrum
The identical modulation degree m = 0.3 for all three components was selected in
ICAO annex-10 [63] such that the total signal still contains 10% modulation reserve.
The carrier is therefore not suppressed at any time. The 9960
Hz reference carrier is
FM modulated with 480
Hz deviation. The VOR signal generation as under ICAO is
shown below.
VOR Mode (Option R&S
EVSG-K2)
