radio free king
2nd October 2002, 09:28
Just copied a very interesting feature from mediumwave.de Ideas About The Future Of Medium Wave
Sound Quality must be improved
Because of the poor sound quality, the medium wave has become very much out-of-fashion in many parts of Europe. In some countries, it is still alive though, e.g. in the UK and Spain or America. In these countries MW programmes exist, which cannot be heard on FM. This is the key to MW attraction I think. However, MW stations often have less success because of the poor sound.
Is DRM the future?
The digital standard DRM (in Europe) is currently pushing forward and will probably be introduced sooner or later. The DRM-site claims that FM-sound quality (mono) will be possible on medium wave. As a matter of fact this is nonsense because you can hear the strong digital reduction to 48K in MP4AAC. Listen to the audio examples on the DRM website. Nevertheless, compared with today's AM sound the DRM appears to be an improvement. There are less problems with fading. And you would only receive one station at a time. Probably DRM would be an improvement but it would take time.
DRM introduction would take time
New receivers would be needed for DRM. In poorer countries only few people could afford them immediately. If you've ever had a look at radios in 3rd world countries this becomes clear: People still use receivers from the 60ies and 70ies, they repair them again and again. It would take much time until all receivers are exchanged.
In the rich world people could afford new receivers. But only a few would buy them. The big majority is not so interested in radio and satisfied with FM. International radio does not attract people so much. This is why people wouldn't spend too much extra money on DRM. The only chance is that DRM technique must becomes as cheap as normal AM. Then the industry would start building FM/DRM radios as they now produce FM/AM combinations. In the best case, the DRM community would grow slowly. So it would again take many years.
Is a co-existence of DRM and AM possible
At least the DRM-developers claim that. On the other hand independent peolpe who observed the test transmissions report that DRM causes a lot of background noise which is not limited to the DRM channel. If you live close to a DRM transmitter whole segments of the MW seem to become useless. The second question is if you can still decode DRM if there is an AM transmitter in the background. Unfortunately I haven't had an opportunity to test it yet.
Wide-band AM could help from one day to another
For the transition time before the complete introduction of DRM something must be done, too. Wideband-AM would be the sollution. The existing AM standard could be boosted up easily from one day to another and provide half-hifi-sound. Wideband-AM would be up- and downward compatible with all existing receivers. Right now, the audio bandwidth is 4.5 kHz. This is not much better than telephone sound. You can't really enjoy music like that. With 8 kHz it's half-hifi. 8k is the maximum possible because AM carriers are covering the band in 9k-steps. Wideband can be easily be introduced in the daytime Most receivers would play the 8 khz sound already now, because they have a bad selectivity. The old disadvantage becomes the key to a better sound.
Maybe the bandwidth should be increased in the night, too. In the night there is inly the problem that interefering neighbouring channels could interfere with each other. Strong stations would push down the weaker and distant ones, but most people are more interested in their local station with a clear signal anyway. If you suppress one modulation side band, even the interference problem could be solved.
Limit networks with different transmitters to one frequency (simulcasting)
this would lead to less interference
there would be more space for new stations
listeners would know "their" frequency wherever they are
There are networks which use up to 20 frequencies for the same programme. This has historic reasons, but today it leads into chaos. In the old days it was difficult to modulate transmitters exactly simultaneous. As soon as you received two transmitters of one program, there would be a terrible echo. Today with satellite feeds, simulcasting is no problem anymore. So why should these networks waste the frequencies. Listeners appreciate to know their station in one and the same place. This is why networks should only use one frequency. Transmitters should be launched close to every big cities and work with up to 10 kW. Big transmitters over 50 kW in the daytime are a stupid concept anyway because they don't get much further with all the power. One-frequency networks with small-sized transmitters in many cities would reach much more people with a strong signal, because the people are closer to the transmitters then. In the countryside, signals would be the same. This concept already works in England where nation-wide Virgin Radio has many transmitters on 1215 khz (there are also some low power transmitters on other frequencies). As soon as stations join together in the night for a common programme, only one frequency should remain. I'd suggest such a strict regulation because the interference situation at night is the worst.
Sound Quality must be improved
Because of the poor sound quality, the medium wave has become very much out-of-fashion in many parts of Europe. In some countries, it is still alive though, e.g. in the UK and Spain or America. In these countries MW programmes exist, which cannot be heard on FM. This is the key to MW attraction I think. However, MW stations often have less success because of the poor sound.
Is DRM the future?
The digital standard DRM (in Europe) is currently pushing forward and will probably be introduced sooner or later. The DRM-site claims that FM-sound quality (mono) will be possible on medium wave. As a matter of fact this is nonsense because you can hear the strong digital reduction to 48K in MP4AAC. Listen to the audio examples on the DRM website. Nevertheless, compared with today's AM sound the DRM appears to be an improvement. There are less problems with fading. And you would only receive one station at a time. Probably DRM would be an improvement but it would take time.
DRM introduction would take time
New receivers would be needed for DRM. In poorer countries only few people could afford them immediately. If you've ever had a look at radios in 3rd world countries this becomes clear: People still use receivers from the 60ies and 70ies, they repair them again and again. It would take much time until all receivers are exchanged.
In the rich world people could afford new receivers. But only a few would buy them. The big majority is not so interested in radio and satisfied with FM. International radio does not attract people so much. This is why people wouldn't spend too much extra money on DRM. The only chance is that DRM technique must becomes as cheap as normal AM. Then the industry would start building FM/DRM radios as they now produce FM/AM combinations. In the best case, the DRM community would grow slowly. So it would again take many years.
Is a co-existence of DRM and AM possible
At least the DRM-developers claim that. On the other hand independent peolpe who observed the test transmissions report that DRM causes a lot of background noise which is not limited to the DRM channel. If you live close to a DRM transmitter whole segments of the MW seem to become useless. The second question is if you can still decode DRM if there is an AM transmitter in the background. Unfortunately I haven't had an opportunity to test it yet.
Wide-band AM could help from one day to another
For the transition time before the complete introduction of DRM something must be done, too. Wideband-AM would be the sollution. The existing AM standard could be boosted up easily from one day to another and provide half-hifi-sound. Wideband-AM would be up- and downward compatible with all existing receivers. Right now, the audio bandwidth is 4.5 kHz. This is not much better than telephone sound. You can't really enjoy music like that. With 8 kHz it's half-hifi. 8k is the maximum possible because AM carriers are covering the band in 9k-steps. Wideband can be easily be introduced in the daytime Most receivers would play the 8 khz sound already now, because they have a bad selectivity. The old disadvantage becomes the key to a better sound.
Maybe the bandwidth should be increased in the night, too. In the night there is inly the problem that interefering neighbouring channels could interfere with each other. Strong stations would push down the weaker and distant ones, but most people are more interested in their local station with a clear signal anyway. If you suppress one modulation side band, even the interference problem could be solved.
Limit networks with different transmitters to one frequency (simulcasting)
this would lead to less interference
there would be more space for new stations
listeners would know "their" frequency wherever they are
There are networks which use up to 20 frequencies for the same programme. This has historic reasons, but today it leads into chaos. In the old days it was difficult to modulate transmitters exactly simultaneous. As soon as you received two transmitters of one program, there would be a terrible echo. Today with satellite feeds, simulcasting is no problem anymore. So why should these networks waste the frequencies. Listeners appreciate to know their station in one and the same place. This is why networks should only use one frequency. Transmitters should be launched close to every big cities and work with up to 10 kW. Big transmitters over 50 kW in the daytime are a stupid concept anyway because they don't get much further with all the power. One-frequency networks with small-sized transmitters in many cities would reach much more people with a strong signal, because the people are closer to the transmitters then. In the countryside, signals would be the same. This concept already works in England where nation-wide Virgin Radio has many transmitters on 1215 khz (there are also some low power transmitters on other frequencies). As soon as stations join together in the night for a common programme, only one frequency should remain. I'd suggest such a strict regulation because the interference situation at night is the worst.