User:Ryan Cooley/DAB

Rough Draft. Probably take a month to look like anything.

Digital Audio Broadcasting (DAB, or EUREKA-1xx) is a standard for transmitting lossy encoded digital audio.

RF

OFDM:

 Multipath, Doppler Shift, Interference.
 Inter-Symbol Interference (ISI)
 Fast Fourier Transform (FFT)
 QPSK - eliminates need for channel equalization
 Guard Interval 
   1/4th symbol length interval
     copies end of symbol before start of symbol
   Multipath
   Single-Frequency Networks (FSN)
 Synchronization
   Null symbol
   Phase Reference Symbol (PRS)

Frequency-Domain Multipath

 Convolutional Coding (Coded OFDM)
   Normally; half-rate. == 1.2Mb/s
 Viterbi
 Bit-stream re-ordering; Pre-determined patterns
   Temporal:  Between Frames; depth 360ms
   Frequency: Interleaving.  

4 transmission modes, 1,2,4,8KHz wide

 Mode 1: Band III (4x1.54MHz DAB in 7MHz UKTV space)  
   70km max SFN antenna spacing
 Mode 2: L-Band (1452-1492MHz, world) 
   est 17km max SFN antenna spacing
 Mode 3: up to 3GHz for satellite
   est 8km max SFN antenna spacing
 Mode 4: L-Band, sometimes appropriate
   est 35km max SFN antenna spacing

6 x 192Mb/s MP2 = 1.2Mb/s Fast Information Channel (FIC) - Non-interleaved

 Multiplex configuration information 
 Service Information (SI)

24ms frames

Data Services

UK

 "The BBC covers 85% of the UK population"