DRM – Digital Radio Mondiale - Digital Video and Audio Broadcasting Technology - page 514

The channel bandwidths specified for DRM are derived from the band-
widths normally used in the frequency bands provided. The DRM band-
widths are between 4.5 kHz und 20 kHz (Fig. 30.2.) and are defined via
the parameter of "spectrum occupancy“. Table 30.1 shows the possible
bandwidths. As in other standards, too, which define COFDM as the
modulation method, modes are defined here. The DRM modes are desig-
nated as Robustness Mode A, B, C and D. The mode determines the carrier
spacing and the symbol duration. The physical parameters of the DRM-
modes can be seen in Table 30.2. The number of carriers in an COFDM-
symbol depends on the mode and on the DRM bandwidth. The number of
carriers which can be accommodated in a symbol is listed in Table 30.3.

Normal
protection MSC: 16QAM/64QAM

FAC: QPSK
SDC: QPSK/16QAM

Normal/
[high]
protection

Audio

Source
encoder(s)

[high
protection]
Normal
protection

Energy
dispersal

Channel
coder

Cell
interleaver

1…4
services

MUX

Main service channel (MSC)

Data Pre

coder

Pilot
generator

[high
protection]

RF

Fast access channel (FAC)

FAC
info

Pre
coder

Energy
dispersal

Channel
coder

SDC
info

Pre
coder

Energy
dispersal

Channel
coder

Service description channel (SDC)

Fig. 30.1. Block diagram of a DRM modulator

Table 30.1. DRM bandwidths

Spectrum
occu-
pancy

0 1 2 3 4 5

Channel
bandwidth
[kHz]

4.5 5 9 10 18 20