DAB+ for the sake of your ears

To find out exactly if your car antenna can receive DAB+ frequencies (174MHz – 240MHz) you need an HF spectrum analyser. If you don’t have this device, an antenna signal splitter and a radio that can receive DAB+ will be sufficient to check if the signal is strong enough.

If there is no DAB+ signal you need to decide what type of “signal provider” is best for the respective vehicle. Bear in mind the following: Nothing compares to a well positioned external antenna. Much of what is installed internally will be second best, depending on the vehicle. Vehicles with Diversity in the rear windscreen will often offer the option to change one or both antenna amplifiers and to receive DAB+ signal at least from one antenna. An ideal prerequisite for using an FM / DAB+ signal splitter.

There are ACTIVE and PASSIVE signal splitters.

When do you need an ACTIVE signal splitter and when a PASSIVE one? ACTIVE signal splitters have an integrated antenna amplifier. The ACTIVE signal splitter will be installed in vehicles which have a built-in PASSIVE, non-amplified antenna. The amplification from the antenna signal enables the frequencies to be split into DAB+ and FM.

The PASSIVE splitter will be required for car antennas that have ACTIVE, i.e. amplified antennas fitted, for example in the rear windscreen or on the roof. All PASSIVE splitters are fitted with phantom power to supply the amplifiers of the vehicle antennas with power.

HOW TO ESTABLISH IF THE VEHICLE ANTENNA HAS AN AMPLIFIER Use a tester (for example RTA 203.050‐0)at the antenna output of the factory head unit will show 8,5V, 12V or NO VOLTAGE. If no voltage is present, you will usually need an ACTIVE splitter. Older vehicles also obtain their power supply via the PIN "antenna / antenna remote" in the radio connector. If any voltage is present, a PASSIVE splitter will be required.

There are exceptions for which there are no technical explanations, e.g. Fiat Ducato with mirror antenna. This antenna has an amplifier but still needs an active DAB splitter. Some models, e.g. from Jeep, with passive rod antennas receive such a strong DAB+ signal that a passive rather than an active DAB splitter has to be used.

Apart from the better sound quality, DAB+ has another very positive effect for the listeners: No noise like there is with VHF. If the receive level becomes too low reception will be interrupted abruptly and, in contrast to FM, remains mute.

The HE‐AAC v2 standard allows DAB+ reception even at relatively low bit rates. From 80 Kbit/s, 12 to 18 audio programmes can be transmitted in one “ensemble”, also called frequency blocks.

If the frequency range of the factory-fitted antennas is not restricted, they can receive DAB+ without the need for an additional antenna. Sometimes it may be sufficient to just change the antenna rod. In such cases an antenna signal splitter will be enough to achieve crystal clear DAB+ reception.

Digital Audio Broadcasting ran as a Eureka project with EU funding from 1987 to 2000, was abandoned and then revived asDAB+. DAB+ is a digital transmission standard for terrestrial reception of digital radio at a frequency range of 174 MHz ‐ 240 MHz. The car industry is offering more and more models with DAB+ tuners. This would justifiably suggest that DAB+ may in future be considered not only a digital standard but the only radio source in vehicles.