Explanation; Circuit Description - Pioneer GEX-P900DAB Service Manual

GEX-P900DAB

7.3 EXPLANATION

7.3.1 CIRCUIT DESCRIPTION

- What is DAB?
Digital Audio Broadcasting (DAB) is digital broadcasting for mobile communications using the MUSICAM (MPEG
Audio) audio compression system. The system was developed by the EUREKA 147 in Europe. For the digital modula-
tion system, DAB uses Coded Orthogonal Frequency Division Multiplex (COFDM) based on multicarrier.
Internationally, DAB is also called as SYSTEM A in ITU-R.
L-band
1452-1492MHz
Digital broadcasting may be called differently in some countries or areas. Even if the system is the same as DAB, it
may be called in different name.
DAR: Digital Audio Radio (IBOC, IBAC or DAB in the United States)
DRB: Digital Radio Broadcasting (DAB in Canada)
DSB: Digital Sound Broadcasting
- What is Coded OFDM?
Although OFDM technology has been known over years, it has recently attracted attention along with development of
FFT technology. In DAB, the system encodes and transmits signal.
1) Encoding is error correction using convolutional code. Compared with codes used in CDs (block code), convolution-
al code is more effective to handle random errors. Generally, it is called Viterbi decoding.
2) DAB signal requires wide band (1.54 MHz), and is given priority to be allocated to 12 channels of TV in Europe (5-13
channels under the standard). Also used is L-band (1.5 GHz).
When DAB signal is allocated to TV 12 (approx. 7 MHz)
12A
Calculating based on band mode 2 will be: 4 KHz × 384 = 1.536 MHz Thus, 1.54 MHz.
Mode 1 1 KHz (1536)
Mode 4 2 KHz (768)
Mode 2 4 KHz (384)
Mode 3 8 KHz (192)
54
DAB receiver
VHF FFT
174-240MHz
COFDM decoder
12B 12C
1.54MHz
Band 3 (VHF)
L-Band (1.5 GHz)
L-Band (1.5 GHz)
3 GHz
Viterbi
Musicam
decoder
12D
Carrier interval: 1 KHz
Number of carriers: 1536
4-phase QPSK for every carrier
2 bits for every carrier
SFN (terrestrial)
SFN (suggested by Canada)
Local (terrestrial and satellite)
Cable