meet the requirements for noise figure, but left the amplifier chip much more exposed to interference from out of band signals - one set of measurements showed a reduction in tolerance to some interference signals of 15 dB. Creative certainly, but not in the spirit of the regulations! So a small drafting group created a new version of the standard, v1.2.1, that was eventually approved by ETSI in September 2025 (the whole process had been put on hold for quite a long period). This version has classifications 0, 3 and 4 removed, and has a much improved immunity test that should be simpler for test labs to implement, while closing the loophole described above. The remaining question is about if and when the new standard becomes applicable in the UK. The latest edition of the list of references to standards for radio equipment in support of the Radio Equipment Regulations 2017 (dated 25th September, 2025) published by the Department for Business and Trade still shows v1.1.1 of EN 303 354. It is hoped that in due course this will be revised to refer to v1.2.1.
To cater for various scenarios that were anticipated at the time, the standard defined five classifications of selectivity that could be used, but as time went on, three of these became obsolete as frequencies above 694 MHz went out of use for broadcasting across Europe. To measure the immunity of the amplifier to strong signals on other frequencies The standard referenced a measurement process defined in an existing CENELEC standard, which turned out to be quite difficult to implement, and in some respects was more demanding than it needed to be. Furthermore, we found that some enterprising manufacturers had found a loophole in the standard that allowed an amplifier to pass all the individual tests within the standard, while not providing the required robustness against interference. Filtering had been split and applied either side of the internal amplifier chip, instead of placing it all before the chip. This gave the required overall frequency response and made it easier to
45 CAI Feedback Winter 2025
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