A week or so ago, as I write, I was in a discussion over the origin and growth of the use of initials as abbreviations. One member of our group mentioned that it was the railways which made such usage commonplace and pointed out that even after years of nationalization people still referred to the LMS and particularly the GWR. All agreed that 'initialing', like the creation of acronyms, was a growth industry and one sage did not hesitate to blame it all on the BBC-possibly this century's most popular abridgement. All of which leads me to the introduction of yet another set: RDS-Radio Data Service. If you have recently acquired a car radio it is likely that you will already have met up with this development, for many of its current features have particular application to radio on the move. However, radio tuners for the home are now appearing which incorporate some of its services; this is the second Sony tuner to do so, although it is the first in their ES range. Others have been announced by such as Pioneer.
So what is RDS? Put simply it is the ability to display additional information in a visual form without detriment to the normal programme. To achieve this a small (about three per cent) additional 57kHz carrier is broadcast alongside the regular stereo signal at exactly three times the stereo pilot tone frequency of 19kHz. This carrier is rather cleverly modulated to represent the noughts and ones of a digital data stream, the rate of which is chosen to have the required information capacity for the service, both currently and as envisaged in the future. The system, which originated in the BBC. is now approved for Europe and is currently carried by all BBC FM transmitters in England (the remainder of the UK is being equipped now) and by a few of the ILR (Independent Local Radio) stations, for example Capital. As currently deployed it can display the name of the tuned station; provide the correct time (updated every minute, on the minute) and date; select the strongest transmission in a group carrying the programme you have chosen; switch your tuner to a station carrying a local traffic announcement or an emergency announcement and restore it on completion. All this can be provided automatically but there are future possibilities which would involve staffing and their provision depends on public acceptance of the system. They might include the title of a programme of the piece of music being played, or 'phone-in' numbers (up to 64 characters); automatically seeking and tuning to a particular type of service, e.g. news, drama, sport etc.; feeding your own computer with information such as sports results or money market details.
It will be apparent that a fixed installation tuner is not required to incorporate these facilities and indeed this Sony does not do so. However, as the presence of those that are there demands the inclusion of a dot matrix fluorescent display or something similar, as a read-out device, and as it has to provide a full upper and lower case alphabet, numerical and numerous symbols, it can be asked to do other things. Thus it is made possible to provide your own eight-character name or description for other non-RDS transmissions on AM as well as FM bands, which will automatically appear when these programmes are recalled. Thirty frequencies, culled from all three wavebands, can be recovered from a user filled memory by means of ten pushbuttons beneath the display panel plus a Shift key which allocates them to A, B and C groups. These are then indicated when called up as A2, B6, C4 etc. As is usual in modern designs, the memorized details, which can include other relevant reception settings, are retained for about a month even if the tuner is no longer connected to the mains. Another little facility is to indicate on request the actual signal strength of a received FM transmission at the aerial in decibels. This can be used in conjunction with a 15dB attenuation button when dealing with a very strong local signal which might otherwise produce overload cross-modulation problems. It is allied to a small bar-graph indication of signal strength to be used when setting up the memory or generally tuning around.