is a supremely energy-efficient mechanism for delivering information globally and should not therefore be discounted. It is not just radio but can distribute text, pictures and html files. As we shall see in later chapters it may also have a role to play in public safety and disaster relief. Short-wave radio irrespective of whether it is analogue or digital will almost certainly continue to be important politically and educationally. The National Association of Short Wave Broadcasters5 issues a monthly newsletter highlighting examples of the difference that short-wave radio continues to make particularly in countries where unrestricted access to the internet is not allowed. 15.3 COFDM in DRM The DRM system uses COFDM with the number of subcarriers variable to suit channel allocations and required range (transmission resilience). There are three different types of audio coding. MPEG4 AAC audio coding is used as a general-purpose audio coder and provides the highest quality. MPEG4 CELP speech coding is used for high-quality speech coding where there is no musical content. HVXC speech coding can be used to provide a very low bit rate speech coder. DRM is therefore effectively a (very) wide-area version of DAB and DMB and was fully ratified as an ETSI specification (the ETSI ES 201 980 V1.2.2 4 www.drm.org. 5 http://www.shortwave.org/ Making Telecoms Work (2003/2004) DRM system specification and 101.968 V1.1.1 (2003-4) data casting standard. In parallel, the ITU ratified DRM for use in the medium-wave AM and long-wave frequency bands in Regions 1 and 3 (Europe, Africa, the Middle East, Asia and Australia/New Zealand). 15.4 Social and Political Impact of the Transistor Radio Integrating broadcast receivers into small form factor hand-held devices is not particularly new as a design concept. There is some dispute as to who produced the first 'pocket-size' transistor radio. A product called the 'Regency' introduced in October 1954 came to market in parallel with early Texas Instruments pocket radio receivers. This trigg