A few weeks ago my new corporate car was delivered, a BMW 5 series (I love Europe). I went for diesel (because everyone does) and have been enjoying it until I realized … it is haunted.

Whenever I am driving the radio will randomly come on. One moment it is quiet, the next moment some local radio station is blaring the traffic. I shut it off. A few minutes go by, it comes back on. Or I am listening to my Zune (there is an auxiliary in jack) and all of a sudden it will switch to a radio station blaring the traffic.

With a new car, this is particularly annoying as I thought it was broken. The guys in the office had a good laugh when I told them about my haunted car. Turns out that the UK has a system called the RDS (Radio Data Systems):

RDS: The Radio Data System

The development of RDS started some 20 years ago in the European Broadcasting Union, EBU. The developers aimed at making radio receivers very user-friendly, especially car radios when these are used where a transmitter network with a number of alternative frequencies (AF) are present. In addition listeners should be enabled to see the programme service name (PS) on an eight character alpha-numerical display and the transmitter frequency information, displayed on non-RDS radios, is then only used, in the background, by an RDS radio. All this has become possible by the using, for many years, microprocessor controlled PLL tuner technology, permitting a radio to be retuned within milliseconds. During this process the audio signal is muted which, because of the short time, is usually not detected by the ear. Thus, the radio is able to choose the transmitter frequency, among a number of alternatives that gives the best reception quality. It is also ensured that the switch-over is made to exactly the same programme service by performing a kind of identity check using the programme identity (PI) code.

Travel information with RDS is possible using the Travel Programme (TP) and Travel Announcement (TA) flags. Information is broadcast for motorists, identified in parallel with the ARI system with the corresponding RDS features TP/TA. But ARI is now being replaced on a European scale, and its operation ceased in 2005. Although there are still some ARI stations in operation in some parts of Germany, this will no longer be so in 2007.

RDS is also used for the digitally coded Traffic Message Channel (TMC), which is introduced all over Europe within funded European Union projects.

Once a radio is tuned to a programme service broadcast within a network, using the RDS feature.

Enhanced Other Networks (EON) additional data about other programmes from the same broadcaster will be received. This enables the listener, according to his choice, to have his radio operating in an automatic switch-mode for travel information or a preferred Programme Type (PTY, e.g. News) and this information comes from a service that, at a given time, does not necessarily contain such travel information nor broadcasts the desired programme type.

The RDS travel information – which keeps taking over my radio is described as:

Travel Information. A very useful bit of information sent, is something called the ‘TA flag’. Standing for Traffic Announcement, this can be switched on when a radio station starts a travel report, and switched off at the end. The practical upshot of this, is that your RDS radio can switch to a station carrying travel news, or in a car, pause a cassette or a CD, when local travel news is broadcast. For more, see below.

Now, if I could just figure out how to turn this government funded service off!

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