DAB is short for Digital Audio Broadcasting. It is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,002 stations worldwide broadcast in the DAB format, and the number also continuously increases. You can find that many of our car DVD players support DAB.
Good Reception quality
As we all know the radio reception of the aftermarket car DVD players are not as good as the OEM head unit. And if you add DAB function, things will be different.
The DAB standard integrates features to reduce the negative consequences of multipath fading and signal noise, which afflict existing analogue systems.
Also, as DAB transmits digital audio, there is no hiss with a weak signal, which can happen on FM. However, radios in the fringe of a DAB signal, can experience a "bubbling mud" sound interrupting the audio and/or the audio cutting out altogether.
Due to sensitivity to doppler shift in combination with multipath propagation, DAB reception range (but not audio quality) is reduced when travelling speeds of more than 120 to 200 km/h, depending on carrier frequency.
Less undocumented station interference
The specialised nature and cost of DAB broadcasting equipment provide barriers to undocumented stations broadcasting on DAB. In cities such as London with large numbers of undocumented radio stations broadcasting on FM, this means that some stations can be reliably received via DAB in areas where they are regularly difficult or impossible to receive on FM due to undocumented radio interference.
DAB is not more bandwidth efficient than analogue measured in programmes per MHz of a specific transmitter (the so-called link spectral efficiency). It is less susceptible to co-channel interference (cross talk), which makes it possible to reduce the reuse distance, i.e. use the same radio frequency channel more densely. The system spectral efficiency (the average number of radio programmes per MHz and transmitter) is a factor three more efficient than analogue FM for local radio stations, as can be seen in the above numerical example. For national and regional radio networks, the efficiency is improved by more than an order of magnitude due to the use of SFNs. In that case, adjacent transmitters use the same frequency.
Improved features for users
DAB radios automatically tune to all the available stations, offering a list for the user to select from.
DAB can carry "radiotext" (in DAB terminology, Dynamic Label Segment, or DLS) from the station giving real-time information such as song titles, music type and news or traffic updates. Advance programme guides can also be transmitted. A similar feature also exists on FM in the form of the RDS. (However, not all FM receivers allow radio stations to be stored by name.)
DAB receivers can display time of day as encoded into transmissions, so is automatically corrected when travelling between time zones and when changing to or from Daylight Saving. This is not implemented on all receivers, and some display time only when in "Standby" mode. (Similar Features on RDS: 4A Groups)
Some radios offer a pause facility on live broadcasts, caching the broadcast stream on local flash memory, although this function is limited.
In certain areas – particularly rural areas – the introduction of DAB gives radio listeners a greater choice of radio stations. For instance, in South Norway, radio listeners experienced an increase in available stations from 6 to 21 when DAB was introduced in November 2006.
Mono talk radio, news and weather channels and other non-music programs need significantly less bandwidth than a typical music radio station, which allows DAB to carry these programmes at lower bit rates, leaving more bandwidth to be used for other programs.
However, this had led to the situation where some stations are being broadcast in mono, see music radio stations broadcasting in mono for more details.
We have many customers need car DVD players which can support the DAB, we add that function to it. You just need to add a DAB box, and you can enjoy DAB audio feast.