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Say No > Digital Radio Plus: NOT - Say no to DAB+ and its minuses

Introduction

Digital radio started to be introduced in the world since the early 2000s. More recently (2007 and onwards) a push is gaining momentum to try to get radio listeners to switch over to digital. However, digital radio is not all that it is striked up to be.

Promises of so-called 'better' sound quality, better reception, station name display, etc are usualy marred by problems that plague digital transmissions.

The Minuses

Worse than FM quality. The DAB+ bitrate, usually 64 Kbps for nearly all stations, is dismal. Most shared DAB transmitters try to cram more 'stations' onto the one DAB frequency, leading to lower bitrates for each station, and subsequently the audio equivalent of image pixellation.

There is nothing that quite sounds like analogue - DAB+ can have a harsh sound resulting from encoding artifacts due to the underlying MPEG Layer II or AAC audio compression codec being used.  The mellow sound of AM transmissions on the MW band simply cannot be replicated on digital transmissions.

Delayed audio and latency. Nearly all AM/FM stations who simulcast on DAB+ will incur a delay of up to 7 seconds for the digital version. This is because the transmitter must encode the audio and 'buffer' a few seconds of it before being sent to the transmitter, and the receiver also needs to hold its own buffer of 1 - 2 seconds. Only a rare few stations deliberately delay the analogue signal so both analogue and DAB signals will be in better sync. But the delay on DAB+ can be very annoying to listeners who have the radio commentary running alongside their TV when watching live sporting events. In this case it is better to use an anlogue receiver.

High power consumption - portable receivers are available on the market that can receive analogue as well as decode digital transmissions. When running in analogue mode, batteries can last for days or even weeks if used infrequently. But when in digital mode, battery life suffers significantly, by the order of 5 to 8 times less. The decoder circuits (microprocessor, DAC, RAM, etc) are all power-hungry devices. DAB+ uses the AAC codec which is complex to decode, leading to increased signal processing requirements and the need for a powerful microprocessor. It means the receiver can only run for several dozen hours on battery power.

In analogue receivers, most of the electrical power is used to run the audio amplification stages. Very little is needed to run the recieving end of the radio. The opposite is true for DAB+ radios. Most of the electricity is used in the recieving and decoding stages, whist comparatively little is used for audio output. So running a DAB radio even at low audio volume will not significantly enhance battery life as it does for an analogue radio.

When used a couple of hours a day, most analogue pocket transistor radios running off a pair of AA cells will last at least two to three weeks. DAB radios, even with their high-capacity lithium rechargeable batteries, will last at most two or three days away from AC power.

In short, portable DAB+ units simply can't compete with analogue sets when it comes to battery life.

Bulky receivers, long antennas required. At present nearly all DAB receivers are bulky, and almost none would be classed as truly portable. There is yet to be a 'walkman' sized DAB receiver, or at least one that would fit in your shirt pocket that has a decent battery life. The popular 'Pure One Mini' comes close, but you would still be struggling to fit that in an overcoat pocket. The good old analogue AM/FM transistor radio will stay for some time to come.

DAB utilises the VHF radio spectrum. As such, it needs a whip antenna, ideally 1 to 2 metres long. Most portable DAB units only provide a 1-metre built-in whip antenna, which usually needs to be fully extended for proper indoor reception.

Analogue Mediumwave AM receivers have a built-in ferrite bar/rod antenna, and that is all is required for good reception - this is also true of the smallest pocket sized receivers - no long unwieldy whip antennas to deal with. And most local analogue FM stations can easily be heard without even extending the whip antenna in most cases.

Because the DAB signal is so sensitive to interference and low signal strength, any disturbance will cause the audio to stop briefly. But in AM or FM, the only effect would be a slight fuzz, pop or crackle in the audio. So with DAB, you end up missing out on bits of audio, but on analogue, you can still quite easily make out the sounds from any interference or noise.

Weak signals unusable on DAB, less reach - whilst a weak, distant analogue radio station can still be received with some level of intelligibility (albeit with noise and static), a digital receiver will be unable to decode the weak signal, resulting in no audio at all. In marginal cases, the audio will cut in and out.

No ability for DXing. Dxing (or long distance listening) is a hobby some radio listeners engage in. The AM signals on the medium wave band can propogate several hundred kilometers (especially at night). With the right antenna, distant signals can be picked up with good clarity. Listening in to another MW radio station from a neighbouring state or town is not difficult.

However, because DAB uses VHF, signal propogation is nowhere near as good as Medium Wave. VHF communications generally require a near-line-of-sight path for a good useable signal. It is near impossible to listen into a distant DAB+ signal.

Another gadget to clutter your car. Car manufacturers have been reluctant to install DAB radios in vehicles, and for good reason. DAB technology is still in its infancy, and there is no guarantee the technology won't be superseded with something newer in a couple of years time. Analogue AM/FM has been around for many decades, is a tried-and-tested technology and will be with us for the long haul.

The alternative is to buy an in-car DAB+ receiver, which retransmits its audio on an analogue FM requency so your car's existing receiver can pick it up for playback. But such a thing will clutter your car, competing with the GPS, cell phone charger, etc for the cigarette ligher socket. You now have two things to turn on in order to listen - first, your car's built in radio, and second, your DAB receiver. Probably more trouble than it's worth, so you may as well just listen to analogue AM/FM.

When travelling to rural areas, DAB signals will be a rarity. You'll end up listening to the local low-budget analogue station (with no intention of switching to DAB anytime soon) or the stronger AM powerhouses back in town, whose signal actually has decent reach and coverage. Try that with DAB - not a chance! DAB is for local coverage only. No DXing as describe above.

Very susceptible to interference - Electrical impulse intererference generally poses no major issues to an analogue receiver, only causing pops or crackles to appear on the received audio. Such EMI (electromagnetic interference) exists in many places, especially in the home, offices and industrial settings. But on a digital bitstream, electrical interference can easily disrupt and corrupt the precise 1s and 0s being transmitted. The end result ranges from garbled sound for a split second to complete audio muting for several seconds.

Increased greenhouse gases and electronic waste (e-Waste) - as more consumers are sucked into purchasing DAB radios, perfectly working analogue receivers, clock radios, portable 'walkman' type receivers etc will be thrown out, adding to the problem of increasing e-waste. Moreover, the higher power requirements and component complexity will all generate more greenhouse gases in both production and usage. The factory manufacturing the radios will use more resources to produce a receiver. The receiver itself needs more power to run its power hungry decoder circuitry.

Loss of radio hobby and education - 'crystal sets' are one of the first easy to build AM radio receivers an electronics hobbyist can construct. When all radio stations move to DAB, such a thing will not be possible. This will lead to the erosion of the electronics and radio hobby. More and more people will simply take radio for granted, rather than have an interest in the underlying circuits that make them work.

Can be extensive to switch over. Avid radio listeners will have several radios scattered around living and work areas. One in the kitchen, lounge room, bedside, garage/workshop, car, office, pocket, etc. Replacing all of them could cost several dollars - especially if you only want DAB to listen to the 'digital-only' stations.

Because analogue receivers can be found almost anywhere, AM/FM radio will be here to stay.

See also: Don't turn off Analogue TV

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