User:Ryan Cooley/DAB: Difference between revisions
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imported>Ryan Cooley (start rought draft DAB article - autosave) |
imported>Ryan Cooley (autosave) |
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'''Rough Draft. Probably take a month to look like anything.''' | '''Rough Draft. Probably take a month to look like anything.''' | ||
'''Digital Audio Broadcasting''' ('''DAB''', or '''EUREKA- | '''Digital Audio Broadcasting''' ('''DAB''', or '''EUREKA-147''') is a standard for transmitting lossy encoded digital audio. | ||
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Inter-Symbol Interference (ISI) | Inter-Symbol Interference (ISI) | ||
Fast Fourier Transform (FFT) | Fast Fourier Transform (FFT) | ||
QPSK - | differential QPSK - no channel equalization needed | ||
Guard Interval | Guard Interval | ||
1/4th symbol length interval | 1/4th symbol length interval | ||
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Phase Reference Symbol (PRS) | Phase Reference Symbol (PRS) | ||
Frequency-Domain Multipath | Frequency-Domain Multipath | ||
ConvolutionalCoding(COFDM)forward-error-correction(FEC) | |||
Normally; half-rate. == 1.2Mb/s | Normally; half-rate. == 1.2Mb/s | ||
Viterbi | Viterbi | ||
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est 35km max SFN antenna spacing | est 35km max SFN antenna spacing | ||
useful payload (0.6 - 1.7 Mbit/s) available. | |||
6 x 192Mb/s MP2 = 1.2Mb/s | 6 x 192Mb/s MP2 = 1.2Mb/s | ||
Fast Information Channel (FIC) - Non-interleaved | Fast Information Channel (FIC) - Non-interleaved | ||
Multiplex configuration information | |||
Service Information (SI) | reference frequency and timing information | ||
?Service Information (SI) | |||
Main Service Channel (MSC) | |||
MP2 audio | |||
24ms frames | 24ms frames | ||
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standardised by the European Telecommunications Standards Institute | |||
"ETSI specification, EN 300 401 (Second Edition) specifies the transmitted DAB signal." | |||
'CD quality' using bit-rates of 192 kbit/s or above for stereo | |||
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"The BBC covers 85% of the UK population" <ref>http://www.bbc.co.uk/radio/waystolisten/digitalradio/</ref> | "The BBC covers 85% of the UK population" <ref>http://www.bbc.co.uk/radio/waystolisten/digitalradio/</ref> | ||
"In the United Kingdom, 12.5 MHz of Band III spectrum from 217.5 - 230 MHz has been allocated to DAB. This will accommodate seven multiplexes. The BBC has been allocated one of these channels for its national DAB multiplex" | |||
"RDS travel bulletins to interrupt listening," | |||
== World == | |||
"100 million people" | |||
Revision as of 01:54, 29 September 2008
Rough Draft. Probably take a month to look like anything.
Digital Audio Broadcasting (DAB, or EUREKA-147) is a standard for transmitting lossy encoded digital audio.
RF
OFDM:
Multipath, Doppler Shift, Interference.
Inter-Symbol Interference (ISI)
Fast Fourier Transform (FFT)
differential QPSK - no channel equalization needed
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
ConvolutionalCoding(COFDM)forward-error-correction(FEC) 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
useful payload (0.6 - 1.7 Mbit/s) available. 6 x 192Mb/s MP2 = 1.2Mb/s Fast Information Channel (FIC) - Non-interleaved Multiplex configuration information
reference frequency and timing information
?Service Information (SI) Main Service Channel (MSC)
MP2 audio
24ms frames
Data Services
standardised by the European Telecommunications Standards Institute "ETSI specification, EN 300 401 (Second Edition) specifies the transmitted DAB signal."
'CD quality' using bit-rates of 192 kbit/s or above for stereo
UK
"The BBC covers 85% of the UK population" [1]
"In the United Kingdom, 12.5 MHz of Band III spectrum from 217.5 - 230 MHz has been allocated to DAB. This will accommodate seven multiplexes. The BBC has been allocated one of these channels for its national DAB multiplex"
"RDS travel bulletins to interrupt listening,"
World
"100 million people"