DAB Radio is the future of radio in the UK.

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DAB Radio is the future of radio in the UK.

Postby spotify95 » 02 Feb 2020, 16:54

Why am I saying this, despite DAB's negatives?

The current situation is that a large number of DAB stations are still using the old MP2 codec and are in mono, due to lack of bandwidth.
However, a relatively large amount of stations have already switched to the DAB+ standard, which uses a more efficient codec (AAC+) and allows stereo operation even at low bitrates, such as 40kbps or 32kbps. (Ok, they may not sound great at that bit rate, but it's better than certain FM situations.)

The problems with FM:
1. Pirate stations - in large cities, there are various pirate radio stations - and with a lack of frequencies available, these can, and often will, interfere with licensed stations.
2. Large stations with numerous frequencies (e.g. Capital, Heart, Smooth) - a vast majority of local/regional stations have been taken over by large semi-national stations, and due to the nature of these stations, there is significant overlap in coverage from various frequencies. Quite a lot of areas only have one or two choices of station, with multiple frequencies for each (i.e. in my area, I can pick up at least 2x Heart FMs and 2x Smooth FMs with ease - however, Capital FM has just one frequency which is power limited in my direction. On a sensitive/selective receiver, I can get 6x Heart FM and 3x Smooth FM; this duplication is unnecessary and can be used for competing stations to give more choice).
3. Community FM stations: These sound like a good idea, to give local radio to various towns and cities, but is it really a good idea? The frequencies given in some cases are chosen by someone with no knowledge whatsoever of radio signals or physics laws - being 0.1MHz away from a large station (as in point 2 above) is going to cause problems with coverage for people wanting to listen to both the community station in question, and the larger station (especially in out of area/weak signal areas).

A couple of examples highlighting these problems (namely points 2 and 3):
1. MKFM (Milton Keynes) is on 106.3FM and In2Beats FM (Bedford) is on 106.5FM. Both are co-channel with KISS FM UK (Mendlesham), on 106.4FM. The Bedford station has a transmitter on relatively high ground, blasting into Northamptonshire even on 25W power, and line of sight is good between Milton Keynes and south Northamptonshire, hence MKFM is receivable despite a distance of approximately 21 miles between the transmitter location and my home address!
However, in certain atmospheric conditions (known as lift conditions, where signals travel much further than usual), KISS FM UK will come through with no issues on 106.4, having severe adverse effects to In2Beats. I wouldn't be at all surprised if MKFM wasn't adversely affected too in some cases.

2. HFM (Market Harborough) is on 102.3FM. This is a relatively clear frequency where I live, but in other neighboring areas, it may be problematic, since Lincs FM (Lincolnshire/Belmont) is co-channel on 102.2FM. Again, all it takes is certain atmospherics to adversely affect the reception of both stations...

3. Secklow Sounds is a community station for Milton Keynes (yes, Milton Keynes has two community stations). It broadcasts on 105.5FM, which to be frank, is one of the worst frequencies you could choose for such a station. Despite being 20 miles away in a straight line, and on low power, it is interfering with the power-limited Capital FM on 105.4 (Billesdon) - since coming on air, my reception of Capital has worsened, and on my selective Eton E5, you can pick up both Capital and Secklow, depending on where the aerial is placed. Of course, this means that, unless the aerial is placed optimally, neither is received very well!
This is the problem with Capital being on low power (due to Magic London) - if Magic London was on a different frequency, Capital would not be power limited, and 105.5 would not be a viable FM frequency.

4. The area above 107 FM is very crowded in my location. Inspiration FM is a community station for Northampton, on 107.8FM. KISS FM UK is on 107.7FM, from Peterborough (Gunthorpe). Smooth Peterborough is on 106.8 FM, from the same transmitter as KISS. Smooth FM for East Northamptonshire is on 107.4FM, and is from a high power transmitter in Geddington. Both 107.7 and 107.8 are difficult to receive on anything but the Eton, due to the close proximity to 107.4 (and the marginal signal levels) and neither 107.7 or 107.8 are easy to receive on the Eton, due to co-channel interference between themselves!
Plus, to top it off, 106.8 is close to the main Smooth East Midlands frequency (from Waltham), which is 106.6FM - again, a rather crowded area due to the close proximity of 106.5/106.4/106.3FM, and Black Cat Radio (a community station for the St Neots area) is on 107.0FM.
Why couldn't they have picked clearer FM frequency slots for these radio stations...

It is rather strange and ironic that nothing has been placed too close to any of the Heart FM channels in my area, namely Heart 96.6 (Kingsthorpe), Heart 96.9FM (Sandy Heath - though this area is also rather crowded due to 96.6, 96.9, and Smooth 97.2 from Irchester); Heart 97.6 (Zouches Farm / Dunstable), Heart 102.7 (Gunthorpe), Heart 103.0 (Madingley) and Heart FM 103.3 (Bow Brickhill / Milton Keynes). That's a total of 6x Heart FM's that are receivable in the same area!
Maybe Ofcom are trying to stop people from listening to more interesting out of area stations?

The solution: listen to the main stations via DAB (improving coverage where necessary) and shunting these multi-frequency, semi-national stations off the FM airwaves - this would allow AM stations to transition onto FM, truly local stations to appear on FM, and more low power community stations to appear. It would resolve the issues of co-channel interference, as this is not possible with DAM in the same way as it is on FM.

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