French Broadcasters Say 'Non' to DAB

France's four largest radio broadcasters have all said they don't want to use the DAB system, citing that it is outdated, inefficient and expensive. They say that DAB's main problem is its use of the MP2 audio codec which requires high bit rates to provide good audio quality, which results in each DAB multiplex only being able to carry very few radio stations at a good audio quality, which in turn results in high transmission costs because the capital expenditure for each multiplex can only be shared between few radio stations. They say, as I have said many times on here, that it is time to move on from DAB and instead use modern technology, including taking advantage of the higher efficiency that the HE AAC and AAC audio codecs allow.

DMB, DVB-H and DRM all use the HE AAC audio codec, which provides the same level of audio quality at 48 kbps as the MP2 audio codec -- that DAB uses -- provides at 160kbps. Therefore, ignoring any other differences between the technologies, DMB, DVB-H and DRM can all carry 160kbps / 48kbps = 3.33 times as many radio stations as DAB for the same total data capacity. HD Radio also uses a high efficiency audio codec, and the proposed European satellite digital radio system is sure to use one too.

However, the increase in efficiency doesn't stop with the modern systems using high efficiency audio codecs, because DAB uses old technology for its modulation and error correction schemes. Although all of the above terrestrial systems use OFDM modulation, DAB uses differential QPSK (DQPSK) along with an old-fashioned error correction scheme, whereas DVB-H and DRM both typically use 16-QAM, which doubles the spectral-efficiency (bit rate per unit bandwidth), and DMB uses a stronger error correction coding scheme to increase its spectral-efficiency.

Overall, as can be seen in the following table, the increase in efficiency relative to DAB is considerable:

1 - projected value for DRM's extension up to 120 MHz

The above table shows just how much technology has advanced since DAB was designed in the late-1980s, and sums up why the French broadcasters prefer DVB-H and DRM in particular -- DVB-H and DRM are complementary to each other.

As an example, for 1 MHz of spectrum, DAB can carry 4 average audio quality radio stations, whereas DRM can carry 40 average audio quality radio stations! That is a difference too large to ignore in this day and age where spectrum is so scarce.

The French broadcasters also cited DAB as being expensive, and this can easily be understood by comparing DAB with DMB. DAB and DMB can both use the same transmitter network, but DMB can carry over 4 times as many radio stations as DAB can, therefore the cost of building and running the transmitter network can be shared between 4 times as many radio stations, so the cost of transmission per radio station will be 4 times cheaper. The difference in cost of transmission per radio station is even more extreme when DVB-H and DAB are compared, because for equal cost transmitter networks, a DVB-H multiplex can carry 13 times as many radio stations as a DAB multiplex can, thus making DVB-H 13 times cheaper to transmit per radio station.

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