Authors
The ±«Óãtv is leading a working party within the European Telecommunications Standards Institute to provide a Harmonised European Standard, ETSI EN 303 345, on the required performance of broadcast sound receivers. The aim is to ensure that efficient use can be made of relevant electromagnetic spectrum, when increasing demands are being made of it. Selectivity is thus an important issue. There is also a need for good sensitivity. For ‘green’ and economic reasons, broadcasters do not want to transmit more power than necessary. Where interference is not the issue, increasing the sensitivity by a modest 3 dB would allow the transmitted power — and hence energy consumption — to be halved!
On the basis of the above, EN 303 345 lays down the minimum requirements for selectivity, sensitivity and blocking. (Blocking is related to selectivity, and is the ability of the receiver to work correctly in the presence of a large interferer at a distant frequency.) The Standard is all-embracing: AM, FM, DAB and DRM; portable radios with built-in antennas, automotive and fixed receivers requiring external antennas. Not only does it give the performance requirements; it also provides details of how the measurements are to be carried out.
This White Paper aims to explain the performance figures adopted by EN 303 345. Having done that, it looks at the test environment and the problems met when making measurements. Finally, it casts a critical eye on the performance that actual radios achieve. To keep the story manageable, only AM portable radios are covered; FM radios have already been considered in White Paper 349.
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