DAB Explanation (Digital Audio Broadcasting)

Frequencies :

DAB/DAB+ can use VHF frequencies in VHF band around 200Mhz. There is also some frequencies available around 1450Mhz.
As DVBT multiplex, each frequency can support many Radios at the same time.
It uses synchronous technology, which allows to use same frequency for transmitter sending same multiplex in the same area. These frequencies are named "Blocks" and are named like "2A". Here is the list of blocks:

5A	174.928 MHz	5B	176.640 MHz	5C	178.352 MHz	5D	180.064 MHz
6A	181.936 MHz	6B	183.648 MHz	6C	185.360 MHz	6D	187.072 MHz
7A	188.928 MHz	7B	190.640 MHz	7C	192.352 MHz	7D	194.064 MHz
8A	195.936 MHz	8B	197.648 MHz	8C	199.360 MHz	8D	201.072 MHz
9A	202.928 MHz	9B	204.640 MHz	9C	206.352 MHz	9D	208.064 MHz
10A	209.936 MHz	10B	211.648 MHz	10C	213.360 MHz	10D	215.072 MHz
11A	216.928 MHz	11B	218.640 MHz	11C	220.352 MHz	11D	222.064 MHz
12A	223.936 MHz	12B	225.648 MHz	12C	227.360 MHz	12D	229.072 MHz
13A	230.784 MHz	13B	232.496 MHz	13C	234.208 MHz	13D	235.776 MHz
13E	237.488 MHz	13F	239.200 MHz

Frequencies extension for DAB on Cable :

14C	241.360 MHz	14D	243.072 MHz	15A	244.928 MHz	15B	246.640 MHz
15C	248.352 MHz	15D	250.064 MHz	16A	251.936 MHz	16B	253.648 MHz
16C	255.360 MHz	16D	255.360 MHz	17A	257.072 MHz	17B	258.928 MHz
17C	262.352 MHz	17D	264.064 MHz	18A	265.936 MHz	18B	267.648 MHz
18C	269.360 MHz	18D	271.072 MHz	19A	272.928 MHz	19B	274.640 MHz
19C	276.352 MHz	19D	278.064 MHz	20A	279.936 MHz	20B	281.648 MHz
20C	283.360 MHz	20D	285.072 MHz	21A	286.928 MHz	21B	288.640 MHz
21C	290.352 MHz	21D	292.064 MHz	22A	293.936 MHz	22B	295.648
22C	297.360 MHz	22D	299.072 MHz

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DAB block


One DAB block can handle many Radios, each radio is independent. The total capacity of a DAB block is 864 "capacity units".
The provider of the block need to ensure that the summ of each radio capacity is not higher than 864 CU.
Each Radio choose its audio bitrate. The radio can add some datas (for ex traffic datas) on a new PID channel.
The DAB can also add datas on special reserved and normalized part, as for ex "radiotext (DLS)" with the current title and the "slideshow" who can transmit pictures.

The radio need also to choose it's transmit level protection. This protection is adding some datas on transmit part, to allow reception error cancelation in receiver.
The more highest is the protection, better will be the reception. Each radio in a DAB block can have different protection level.

The number of "Capacity units" of one radio is related to the audio bitrate, data bitrate, datas radiotext and slideshow and also by the protection level.
The DAB tables of Digitalbitrate have all these informations, and a multiplex graph is displaying the room used by each radio in term of capacity units.

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AUDIO Encoding


The DAB is using MPEG1 layer 2 for audio encoding.
The DAB+ is using AAC to decrease bitrate needed and to increase sound quality.
The AAC has some audio encoding optimization features:
SBR: spectral band replication
PS: Parametric stereo
The Digitalbirate table is showing id SBR and/or PS are enabled.