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Medium wave
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== Sound quality == The channel steps of 9 and 10 kHz would ordinarily require limiting the audio bandwidth to 4.5 and 5 kHz, respectively, without causing any interference to adjacent channels, because the audio spectrum is transmitted twice, once on each [[Single-sideband modulation|side band]] (i.e. Β±4.5 kHz of carrier frequency for 9 kHz channels and Β±5 kHz of carrier frequency for 10 kHz channels). This is adequate for talk and news but not for high-fidelity music. However, many stations use audio bandwidths up 10 kHz,<ref>{{cite web |url=http://edocket.access.gpo.gov/cfr_2006/octqtr/47cfr73.44.htm |series=Code of Federal Regulations |title=Β§ 73.44 AM transmission system emission limitations |archive-url=https://web.archive.org/web/20110927113038/http://edocket.access.gpo.gov/cfr_2006/octqtr/47cfr73.44.htm |archive-date=2011-09-27 |df=dmy-all}}</ref> which is not [[High fidelity|hi-fi]] but sufficient for casual listening. In the UK, until 2024 most stations used a bandwidth of 6.3 kHz.<ref>{{cite web |url=https://mediumwave.de |title=Medium Wave in Central Europe |date=2020-01-21 |df=dmy-all}}</ref> However in 2024, Ofcom expanded the allowed bandwidth to 9 kHz, giving a noticeable improvement in quality. With AM, it largely depends on the frequency filters of each receiver how the audio is reproduced. This is a major disadvantage compared to FM and digital modes where the demodulated audio is more objective. Extended audio bandwidths cause interference on adjacent channels.
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