Revisiting DAB - and maybe FM

[Dave2002]

Quite by chance today I noted that our DAB tuner was turned on, and apparently tuned in. This due to the action of a cleaner, I think. We haven't used it seriously for years.

I then thought to try it out, and connected the optical output up to the DAC, and got a horrible squelching noise. After a few minuted investigation I noted that the tuner has two optical connections. One is not for the audio output, I think, so I switched to the other. Now - silence! The apparent presence of tuned in stations was due to previous presets - but there was zilch in terms of audio output.

Simple attempts to hook up small pieces of wire did not get any further, so I looked up how to make a simple DAB aerial - and found this -
http://www.audiobritain.co.uk/DAB.html I was able to find about 5 metres of suitable cable, already with F connectors on the end, so I trimmed this down as per the instructions, and tried to hang it up in a window. Managed to pull in stations, but no BBC - the 12B section didn't appear at all. Next modification was to fasten the top to middle end of the wire to a piece of dowelling, and then to prop the whole thing in a window. It just about works - just a faint trace of burbling at times, but I guess that it's marginal. Radio 3 is similar - just doesn't sound fully secure. Radio 2 and some of the other commercial stations in other parts of the DAB frequency ranges do seem more certain.

Perhaps nobody bothers with DAB these days - and for a long while I have wondered whether to get this piece of kit working again. I have similar feelings re my FM devices - we just do not have good enough signals to use simple aerials, and most indoor aerials are not good enough either. Perhaps we should bite the bullet and install decent aerials, but when I checked with an aerial installer over a decade ago I think it was even then going to cost £500 or more to have aerials up on the roof. I don't think our loft space is really good enough for aerials - sadly. Since then we have largely used other ways of receiving radio.

As digital TV became available I also suspected that the TV aerial which had been on the roof perhaps for years before we came here was not working well, but with a few aerial amplifiers it has been driving digital TV tuners sufficiently well, at least until recently, to get acceptable TV reception.

Just to complete the story, the house also came equipped with an old Sky dish aerial and that was probably designed to work with an old analogue box, but I bought a new dual output LNB and fitted that, and fed the outputs into a Humax Foxsat PVR. Mostly that is now the most reliable way of getting TV, and we sometimes, perhaps more than we should, listen to radio via the satellite box.

Lastly, we do have enough computers etc., so we can pick up radio via the internet, but while all this stuff gets the job done, there are those round here (mentioning no names) who just want one box which has understandable controls, to be able to switch between the radio channels etc. That's probably why the kitchen DAB unit gets quite a lot of use, and in the morning the Today programme comes in on a bedside FM radio, and the same radio is used for the late night news before or at midnight.

Does anyone else have similar experiences? Just in case, what DAB or FM aerials does anyone recommend? Maybe there is no point in going that way these days.

[Stunsworth]

I have a large Musical Fidelity DAB tuner that I haven't used in years. These days I stream from the R3 HD feed. There were problems with DAB, particularly the 'bubbling mud' sounds that could occasionally be heard. I can't say I miss it too much.

My 'one box' bedside solution is a Sonos Play 1. Set to wake me up with R3 breakfast.

[Gordon]

First some questions:

Where do you live?
How old is the receiver?
Where is the reciever placed in the house?

Your experience suggests bad signal level though why that should be glven the number of new stations built lately OR possible very poor receiver sensitivity and that excludes the internal aerial. If your receiver design is too poor there is nothing much an aerial can do. Anyway home made aerials can be troublesome because of matching correctly.

Another problem could be local interference blocking the radio. Have you got a home ethernet using the mains plugs - or perhaps neighbour has? If so and the devices are Belkin that could be part of your problem. Some of these devices spray out vast amounts of RFI but they are not regulated and so do not get tested for it for their CE mark.

Have you a local mobile phone mast near you?

One of the problems that has given DAB a bad name is the appalling sensitivity of some early receivers and the biggest culprits were the big names - none mentioned until I find a lawyer - some of them well over 20dB off what they should be. Have a look at this:

http://stakeholders.ofcom.org.uk/bin...es/annex-j.pdf and Figures 8 et seq.

Now there is a Tick scheme to test receivers including their sensitivity but it has yet to be adopted by retailers.

I have had several DAB receivers for years [Sony, Pure, Roberts] and none have given me any problems at all without an external aerial [we can argue about MP2 but that isn't your problem] but the Roberts is rubbish on FM with their own aerials as are all the others. For me DAB works well where FM doesn't.

I am in rural Hampshire and FM on the HiFi won't work at all acceptably without an external 6 element Yagi on the roof pointing at the most powerful transmitter around [Rowridge, not Oxford although it's nearer it's lower EIRP] pulling in about 500-800 microvolts/metre which is what the receiver requires to quiet properly for stereo. You can almost never give a properly designed HiFi FM receiver too much input if you want low noise in your audio. The FM service was designed for external aerials not for portable reception.

[Dave2002]

Actually, challenged by mrs d. before dinner, I've just taken the optical feed from the Humax Foxsat PVR and fed that into an optical switch, so I can compare with the DAB. The satellite system is, at the moment, better. The actual audio quality is similar, but there is no bubbling mud from the satellite receiver. I could probably also put a Freeview/Youview box in, again to compare, though there's probably not a lot of point.

My tuner is a Sony 777ES, which was a very early DAB/FM tuner - but supposedly of very high quality, and cost an arm and a leg at the time. Perhaps that would benefit from amplification on the input side - which is what we do with the TV signals.

We live somewhere south of London, outside the M25 - I'm not going to put an X on the map

[Bryn]

My first DAB receiver was a Psion Wavefinder. Its screw antennae were just not quite enough to overcome the boiling mud effect. However, a chimney mounted simple dipole did the trick. I later got a Sony ST-D777ES as the limitation of having to use the Psion Wavefinder with a PC running Windows 98SE did not offer much when it came to live listening, though the ability to save multiple programmes from the same mux simultaneously was exploited a great deal re. BBC Radios 3, 4, and later Radio 7 (now renamed 4 xtra). When Windows XP came along, that was the end of the Wavefinder. It was incompatible with the new OS. I then got a Pure Bug, again fed from the chimney dipole. Only very rarely (usually when here is a atmospheric thermal inversion) do I get any hint of the boiling mud effect. I live around 30 miles from the Crystal Palace transmitter, but probably also get minor signal contributions from several other surrounding relays. That said, most of my home listening to Radio 3 material is now time shifted via the iPlayer's HD Sound offering, though the optical digital output from the Pure Bug is currently feeding the Onkyo TX-SR309 in the back room I am currently using. FM has become something of a fallback option due to low level electromagnetic interference from my next door neighbour's powered podiatry tools (and I use a chimney mounted 5 element Yagi for FM).

It might be worth trying a simple DAB dipole in the loft. There may be some signal attenuation when the roof tiles get wet, but you should get better results than with a built-in telescopic aerial. Many DAB receivers have an F type aerial socket into which a telescopic aerial is normally fitted. It will probably not be mentioned in the documentation, but may well be there.

[Eine Alpensinfonie]

Set to wake me up with R3 breakfast.

[MrBear]

Enough to ruin anyones appetite

During the festive season I bought myself some seperates for the bedroom one of those micro systems that included a FM tuner and had found it good to be able to listen to a bit of R4 PM and the weekday 8pm to 10pm programmes

A couple after I was thinking It would be good to be able to listen to radio in the Kitchen and bathroom

So I got a second hand Rotel tuner for under a tenner it sounds great and gets perfect reception connected to the roof aeriel which is of the typical tv type

Switched the amp to the tuner the other morning and didnt look what frequency it was set to and thought I was listening to Classic FM but turned out to be R3 the presentation style sound so much like commercial radio to me I assume this is the so called dumbing down of the BBC sounded dumb as to me

As the amp I was using was starting to have issues and I wanted to be able to listen to Radio 4 Xtra I stated looking round at DAB tuners and amps

I picked up a second hand Yamaha 6.1 AV receiver which has DAB quite a nice little amp have it connected to three pairs of speakers I have picked up in charity shops

Also picked up a Marantz MKII SE CD player so have quite a nice little radio set up in the kitchen now almost loud enough to be heard over the fridge microwave boiler extractor fan and kettle I have even turnde of the boiler and fridge when I have wanted to sit back and listen to a CD

Unfortunatley the DAC on the Yamaha receiver seems to be awfull but good enough for Radio 4 Xtra tried listening to CD using the DAC on the Yamaha oh dear wont be doing that again a shame as with a analog input from CD or Fm it does sound good

Not really planned to but just bought a load of second hand stuff I liked the look of and have been liucky with the speakers Not actually listend to much radio but dont really know when stuff is on did catch a really nice lot of Purcell the other evening while snoozing in the bath I use to be a real Radio fan but have got in the habit of only listening to R3 recorded on a freeviw PVR when I know something I want to listen is on so can avoid the verbal drivel and use to listen to soem programs on Radio 4 Xtra this way

One thing I do like with DAB is the programme and date and time information

With the Yamaha I have been getting quite good reception with the short bit of wire aerial it came with and it is downstairs in the back of the kitchen in a terrace so I was really surprised a bit of of the burbling mud sound as I move around but sat in the kitchen arm chair no problems connected to the roof aeriel its really clear

These days for music I would just rather be listening to CDs but do want to listen to news and other stuff on radio but just dont do so really dont think radios are worth spening any real money on DAB sound quality is just to poor for any real serious listening of classical music Years ago I bought an awfull Pure Evoke thing awfull at picking up a signal everytime you moved it it would retune itself had loads of problems with it would not touch there products again with a barge pole awfull customer service a shame as when it did actually work it sounded quite good especially considering the size

I dont think I will be listening to the radio that much just find the quality so poor both sound quality and programme contentthe BBC presenters have become just as annoying a commercial ones Reception wise I can get a really good clear signal just lack of good radio programmes worth listening to I know I am going to get more use out of the Yamaha receiver as a multi channel amp so really good for the bathroom and kithchen

[Stunsworth]

Yeah, I'm a pleb. It's a perfect programme for me to wake up to.

[Gordon]

Actually, challenged by mrs d. before dinner, I've just taken the optical feed from the Humax Foxsat PVR and fed that into an optical switch, so I can compare with the DAB. The satellite system is, at the moment, better. The actual audio quality is similar, but their is no bubbling mud from the satellite receiver. I could probably also put a Freeview/Youview box in, again to compare, though there's probably not a lot of point.

My tuner is a Sony 777ES, which was a very early DAB/FM tuner - but supposedly of very high quality, and cost an arm and a leg at the time. Perhaps that would benefit from amplification on the input side - which is what we do with the TV signals.

We live somewhere south of London, outside the M25 - I'm not going to put an X on the map

I guess where you are you may be in a good coverage area but possibly not if tucked into the N or S Downs.

That Sony tuner was one of the best buys at the time and its spec is probably as good as it gets today so it looks like you are short of signal. Its DAB sensitivity - 7 microvolts - is more than good enough IF you have fed it with enough signal. It has separate antenna sockets for FM AND DAB but those "indoor" antennas are worse than useless unless you can see the transmitter and if not can take a while to lay out just right and then the propagation conditions change and its not right any more.

For FM you are within reach of Wrotham and a couple of low power relays:

http://tx.mb21.co.uk/mapsys/map.php?mapid=3

but for DAB you may be in a low field strength pocket, but looks like new transmitters are due for Horsham and Crawley areas [no dates given]:

http://www.ukfree.tv/transmitters/dab/all/ie/WESTSUSSEXENGLAND

If both FM and DAB are poor and you have no outside antennas [as implied by posts above] then you are short of signal either because you lack an antenna or you are in a pocket of low signal [far from transmitter, in behind hills, tall buildings etc. It's possible that your Freeview signals will be poor too? Your satellite transmissions will be more secure.

You ight find this of interst:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/207937/Domestic_Min__Spec_v1.1_revisedJune13_.pdf

[OldTechie]

Simple attempts to hook up small pieces of wire did not get any further, so I looked up how to make a simple DAB aerial - and found this -
http://www.audiobritain.co.uk/DAB.html

An interesting find. I think all antenna engineers are really magicians, and all attempts to understand how they make things work will fail. There is a better version at http://www.audiobritain.co.uk/A_chea...AB_aerial.html - it has the diagram which seems to be missing on the other page. I'm not convinced that that it is necessary to remove the insulation from the 220mm of exposed outer screen provided the geometry is maintained - but I'm not a magician.

[Gordon]

An interesting find. I think all antenna engineers are really magicians, and all attempts to understand how they make things work will fail. There is a better version at http://www.audiobritain.co.uk/A_chea...AB_aerial.html - it has the diagram which seems to be missing on the other page. I'm not convinced that that it is necessary to remove the insulation from the 220mm of exposed outer screen provided the geometry is maintained - but I'm not a magician.

Agreed on both counts OT!! RF engineering is a black art. This home made antenna design is basically a form of a quarter wave resonant stub but without the usually required ground plane. The 300mm of inner without its braid is roughly tuned to 250 MHz just above the DAB band but may be detuned slightly due to the coils.

I'm not sure what the stripped braid does - why stripped? - and why the length is 230mm but the coiled section is probably meant to be a sort of simple RF transformer to help with impedance matching so maybe the design is a bit of T&E. It's a bit crude but the strangest things can be achieved with antennas!! One thing an antenna has to do is match the balanced impedance of space - 120*pi or 377 ohms - to whatever the load on the electrical structure is - 75 ohms unbalanced - to assure optimum transfer of power from the wave to the receiver circuits.

Why it would be better than the usual dipole I don't know but a dipole is directional in response and so has to be oriented correctly - vertical and broadside on to the transmitter - but this one isn't and so there are swings and roundabouts. For DAB a dipole would have to be a T with about 335mm for each half of the top arm of the T.

[Dave2002]

Gordon, OT and Bryn

Thanks for the suggestions. Really I'm not sure why I bother, as it may all be irrelevant now, as some of us are finding. We used to live in Chesham (don't mind giving X marks the spot for past abodes - give or take a mile or two ...) at the top of a hill. We had an indoor loft FM aerial - think it was 4 element, and an indoor TV aerial - for analogue TV at the time as digital TV hadn't quite happened. Both were adequate - the FM was satisfactory to good, though I think an outdoor aerial, or one with more elements would have reduced the back ground hiss level to almost inaudible - which it wasn't.

Having moved to another county, with different terrain, the situation is different. I think I have a wideband aerial which was really for TV, but I may have used it for DAB radio - probably in the garage. It's a bit big to put up in our loft. As suggested I could put one of the smaller DAB aerials up there, but then I'd have to run cable down inside and if I were going to do that I'd perhaps want to try for FM as well. That would probably require at least 10 metres of feeder cable for each deployed aerial - though to my surprise I think a 25 metre or even a 50 metre reel can be obtained for not too much - perhaps under £10, so the major costs of installation would be in my time if I tried to find a route, and threaded the cable up there. Whether it would be better to drill a hole through the wall and take the cable(s) outside, and up the wall, then back in somewhere round the gutter I can't say. It would perhaps look neater from the inside, but maybe less so outside.

So, in terms of costs, it might, with luck cost about £50 to get aerials in the loft. OTOH I could just not bother, and carry on using the digital computer feed via the internet, which would work for the BBC stations at least. Otherwise I could use the satellite TV feed from our PVR and tune to the radio channels.

I can see from playing around over the last few days that there are many more stations than just the BBC ones on DAB, but almost without exception I have no interest in them. One other curious thing is that the BBC DAB stations do seem to be at lower power than some of the others, as it is possible to get bearable reception with a simple antenna, whereas the BBC stations definitely need something better. Is this a general feature of BBC TV and radio transmission?

I noticed a similar thing last year in Scotland, where it was not possible to receive BBC TV channels using a modest gain antenna (bought from a shop) from a transmitter at Rosemarkle which I thought I could see out of the window. As I recall, it was possible to receive some, or perhaps most of, the commercial TV channels, but nothing at all from the BBC. However, it is also possible that I was mistaken about the transmitter - the visible one could just have been the one at Mount Eagle, which is a radio tower. Be that as it may, it seemed odd that it was possible to receive some channels, but not the BBC ones.

Given that there are still people who are concerned about FM, perhaps it's not totally unreasonable of me to try to make DAB work, and even FM, but it does seem to me that many of us are going to find it easier and cheaper to use the internet services from now on - the Negroponte shift does appear to be happening, at last - at least in the UK.

[Globaltruth]

When we moved house 5 years ago the DAB coverage was zero.
3 expensive DAB only radios rendered immediate useless....(it would not have stopped us moving of course).
I registered to be kept informed with http://www.ukdigitalradio.com/coverage/postcodesearch/if there was any change. No emails.
When I checked via the website periodically there was still no coverage planned - ever.
Resigned to a life of FM and internet radio I stored the DAB radios in a bottom of wardrobe and thought no more of it.
This week I've invested in a new Roberts Stream 107 which provides internet, FM and DAB.
Idly I set DAB autotune to work expecting the usual sad hiss as zero stations were found.
Lo and behold - 10 stations found!
I fully extended my aerial (oo er missus) - reception excellent. 10 stations - all BBC.
It seems that as of June 2014 we are now covered in Phase 4 of the BBC rollout:

http://www.bbc.co.uk/reception/digitalradio/expansion

I wonder if we'll ever get the commercial stations? At the moment they are very hit and miss - unlistenable with that cracking cornflake sound or non-existent.
I also wonder why, despite registering, no-one ever let me know - another listener falling between the tracks, and I'm guessing someone somewhere will be adding us as a statistic to the '99%' coverage inexactitude. Yes, we have coverage, yes I mainly listen to the BBC but I also want the option of the station that played birdsong 24 hours a day
(actually it's here now http://www.birdsongradio.co.uk/radio...ong-listen.php

Interested to hear of any other DAB reception stories...

[Dave2002]

I'm still struggling with DAB vs online streaming. At present I have my old tuner connected via an optical cable through an optical switch to my DAC, and I also have my MBP laptop connected to the optical switch. It's a matter of about 2 seconds to switch between them.

The DAB is at present still not being fed with a good signal from an aerial - though it does work. The earlier "simple" design model was no good for BBC, though did pull in quite a few commercial stations. I have since tried three other aerials. The best was undoubtedly the large multiple element aerial really intended for outdoor use, which gave moderately reasonable results when I lugged it up to the landing. Currently I have a cheap amplfied aerial with a kind of circle plus two ears. This works, but is very susceptible to bubbling mud, and if anyone moves the quality goes off. I suspect also that it doesn't like the electrical interference from computers, and from Powerline adapters etc. as mentioned by Gordon a few posts back.

The good thing about the DAB is that it keeps going when I close the computer down!

Another possibility is to take the feed from a Squeezebox - which I also have - but I think that may still need to be fed via a computer, rather than picking up a direct transport stream from the Internet. There used to be streams which could be picked up directly by the device, but I think they may no longer be available, or if they are, they may not be the so-called HD streams.

One quite big surprise with DAB currently is the very low level of the R3 volume compared with most other stations. This isn't a major problem (with care) - as presumably it has a wide dynamic range - far more than most speech or pop music stations.
If the bubbling mud can be overcome it actually does sound fairly good, and I enjoyed a bit of the Schumann Nachtlied yesterday - though speakers still sound somewhat unreal in the announcements. The reason that this volume R3 vs the rest is a possible problem is that switching between stations can lead to really large surges in volume, so care is needed.

[johnb]

Another possibility is to take the feed from a Squeezebox - which I also have - but I think that may still need to be fed via a computer, rather than picking up a direct transport stream from the Internet. There used to be streams which could be picked up directly by the device, but I think they may no longer be available, or if they are, they may not be the so-called HD streams.

Just for information - as I understand it, the problem with using the Squeezebox Touch, standalone, with the new live 320 kbps streams is that they are chunked HLS/AAC and the Touch just doesn't have the power to decode those (even if someone amended the firmware). However, the BBC has reinstated the old R3 "HD" 320kbps AAC stream (on a new URL) for a transitional period. Its future will be reviewed at the end of this year's Proms. I understand it is possible to play this "HD" stream on a standalone Touch, though it is a bit fiddly to set it up.

You have to enable "TinyLMS" on the Touch by inserting a USB stick (TinyLMS is a cut down version of LMS that is built into the Touch firmware), set up the "HD" URL on mysqueezebox.com and then save it as a local favourite. The USB stick has to be left inserted into the Touch (to enable TinyLMS), even though it isn't actually used.

The URL for the transitional R3 live 320kbps AAC stream is

http://open.live.bbc.co.uk/mediaselector/5/select/version/2.0/mediaset/http-icy-aac-lc-a/format/pls/vpid/bbc_radio_three.pls

The hacks to get the BBC streams running using the LMS server together with the Squeezebox Touch, etc have now been fairly well buttoned down for LMS running on Windows, Mac, Ubuntu computers and Ubuntu servers (this is probably the case for other flavours of Linux as well) and, in my experience with W7 and Ubuntu Server, they work extremely well. However, where LMS is running on NAS and VM boxes some people experience more difficulty installing the hacks and some have difficulty getting them to work, some people also get buffering problems with those devices.