DAB workshop reception

[Howard LewisParticipant @howardlewis46836]

being purely a mechanical engineer, I would agree, (on the basis of the picture) with the likelihood of the Antenna input being 300 ohm, and with the need to match the antenna and connecting cable impedance to that of the set, to maximise power transfer.

Radio hams usually opt for "as high as possible" for antenna positioning, and in alignment with the transmitter.

At 225MHz the elements of a yagi are going to be pretty short, (digital TV is around 240 / 250 MHz from memory,

So your radio antenna is going to be only a bit larger. A folded dipole is likely be even smaller, end to end.

The data already posted plus a bit of calculation should allow you make reasonable antenna, and position it for best reception.

Having said all this, I very rarely switch on the FM radio in my shop! Too busy metal mangling!

Howard

[Clive IndiaParticipant @cliveindia]

Posted by KWIL on 09/01/2016 12:37:24:

You have to remember that the BBC is no longer in charge of the transmitters. All stations are run by Arquiva, so do not blame the beeb.

Only partially correct. They are run by Arqiva under contract to BBC. The BBC are still totally responsible for the transmission of their services both in quality and availability.
 

Posted by Howard Lewis on 10/01/2016 15:29:17:

At 225MHz the elements of a yagi are going to be pretty short, (digital TV is around 240 / 250 MHz from memory, o your radio antenna is going to be only a bit larger. Howard

Digital TV is transmitted in Bands 4 and 5, channels 21-68, give or take some in the middle being hived off. The frequency is between about 480MHz and 900MHz and DAB is in Band 3 at about 225MHz, so quite a bit different.

There should be no problem in receiving TV and radio in Boston since it is only about 30 miles from the high power transmitter at Belmont which has a mast of 1265ft, line of sight and 30 miles away, providing there is nothing in the way. The problem is usually a poor aerial being used inside, instead of a decent aerial outside at a good height.

 

Edited By Clive India on 10/01/2016 17:05:18

[JonParticipant @jon]

Its been 30 odd years since dabbled with radio and aerials though easy to make.

I still use an early 2002 or 3 Roberts DAB Gemini 25 RD-25 discontinued around 12 years ago able to pick up, just checked 36 stations was 59 at one point. Ultra rarely get dropouts perhaps twice a year used daily with standard taped together busted aerial.
Around 2006 bought several Pure Dabs able to receive but not listen without 80% drop outs 6 stations.
Newer Roberts have two more received back then around 40 odd stations any where.
Took plunge in 2008 and bought a Cowan D2 DAB using ear phones as the aerial, again 59 stations even in the middle of no where. SN and Sensitivity better suited to DAB than nearly all other radios and you will be making an ill informed choice just picking something off the shelf from Asda that more than likely will be useless.

Same time pondered over an Alpine DAB in car via extra tuner box, I bottled out knowing would be useless when moving and an uncertainty over Signal to Noise Ratio and Sensitivity being ok.

One or two transmit above 128 kbps but not many more suited for tonal quality than stereo imagery but good enough when machines are running and I was a hifi freak up to 25 years ago, says something.

Noticed over 13 years more and more stations pulling out of VHF and DAB going internet only. Luckily have Ethernet hard wired in to workshop done 12 years ago, so when Roberts packs up, cant believe its still going I would go Internet route but what to get?

[BazyleParticipant @bazyle]

If you go internet keep an eye on the data rates and accumulated data usage unless you are on an unlimited tariff.

[michael howarth 1Participant @michaelhowarth1]

Posted by Clive India on 10/01/2016 16:09:36:

There should be no problem in receiving TV and radio in Boston since it is only about 30 miles from the high power transmitter at Belmont which has a mast of 1265ft, line of sight and 30 miles away, providing there is nothing in the way. The problem is usually a poor aerial being used inside, instead of a decent aerial outside at a good height.

Edited By Clive India on 10/01/2016 17:05:18

The proximity of the Belmont transmitter just adds to the frustration Clive. I would have thought that being so close it would blast out transmissions on a crystal set!

Mick

[Michael GilliganParticipant @michaelgilligan61133]

Mick,

For what it's worth … Here is the Ofcom DAB Coverage Plan for Lincolnshire.

I still think the biggest problem is Sony's receiver [and the instructions!]

Have you tried another receiver in the same location ?

MichaelG.

[michael howarth 1Participant @michaelhowarth1]

Thanks for that Michael and I wish it were that simple. I have just bought a new car with an allegedly state of the art DAB radio and the problems are similar if not worse. It is a common complaint in this area. Having said that I think that the flimsy aerial connection to the Sony is a poor show.

Mick

[Michael GilliganParticipant @michaelgilligan61133]

Mick,

It does took like there are local area problems

It may be worth keeping an eye on this site.

MichaelG.

[michael howarth 1Participant @michaelhowarth1]

Michael, I think that that site and attached comments tell it all in a nutshell. Strangely, or even perversely the coverage map for 11D does not seem to cover Skegness…….but I went to Skegness yesterday and reception for LBC was perfect, cutting in at Wainfleet!  I was beginning to think that I might be the problem!

Mick

 

Edited By mick H on 11/01/2016 08:30:52

[Michael GilliganParticipant @michaelgilligan61133]

Mick,

Looking at this version of the map, I notice that you are almost equidistant from three major DAB transmitters. … I am way out of my depth, now, but I suspect that a directional antenna would help a lot.

Multipath reception causes 'birdies' on FM, but Digital probably just fails !!

Hopefully, others can advise in detail.

MichaelG.

[Clive IndiaParticipant @cliveindia]

Posted by Michael Gilligan on 11/01/2016 08:42:16:

Mick,

Looking at this version of the map, I notice that you are almost equidistant from three major DAB transmitters. … I am way out of my depth, now, but I suspect that a directional antenna would help a lot.Multipath reception causes 'birdies' on FM, but Digital probably just fails !!Hopefully, others can advise in detail.MichaelG.

I understand your thinking Michael and the logic. However, DAB is not transmitted in the same way as FM.

It is much more resilient to multipath.

National DAB is transmitted on a single frequency network which is synchronised and therefore the problem you highlight is addressed.

[Michael GilliganParticipant @michaelgilligan61133]

Clive,

I bow to your wisdom.

MichaelG.

[Neil WyattModerator @neilwyatt]

DAB is wonderful.

Unlike old FM where you had to make a subjective judgement of signal quality, with DAB you actually get the bit rate and transmission type.

Now you have a display that tells you that what used to be your favourite FM stereo station is now 80k mono (256k is the "Digital Audio Broadcasting (DAB) MP2 bit rate required to achieve a high quality signal".

So although the audio quality is crap, at least it it honest and tells you that it is. Isn't technology wonderful.

Oh, I should also mention it scans automatically and tells you all the stations it can almost pick up.

Neil

[Martin ConnellyParticipant @martinconnelly55370]

You can use FM radios in the workshops where I work but DAB is useless. Lots of metal in the walls, roof and stanchions is probably why the big difference.

Martin

[michael howarth 1Participant @michaelhowarth1]

I thought that I had cracked it this morning……I searched around for a place where it seemed to be picking up a good signal and reinstalled the Sony. All was well for at least half an hour….then LBC faded out followed almost immediately by Classic FM. Back to the drawing board. Nearly forgot, it is back on now.

Mick

[John HaineParticipant @johnhaine32865]

An old friend was Chief Engineer at the UK company that supplies the chip technology in a large proportion of all DAB receivers sold. His job was to develop reference designs for radios that companies could make using their chips. They make extremely good chips, but it is very hard to overestimate the ability of an average consumer electronics designer to trash the performance of a perfectly good chipset by stupid product design. Usually this takes the form of an idiotic antenna driven by "styling" more than function. For example – "can we use a metre of wire out of the back of the set as an antenna?" Er – well, if you must. Then the stylist doesn't like it so they wrap the wire round the magnet of the loudspeaker to "keep it out of the way". Or run the antenna connector past the switched-mode power supply.

So DAB can be very good, but it does need a sensible antenna. I had a Quad FM tuner which gradually lost sensitivity, using an outside aerial on the chimney. Aerial blew down, got it replaced with a combined DAB/FM antenna, bought a DAB/FM tuner in a Richer Sounds sale, it is absolutely excellent in sensitivity and sound quality, easily better than the Quad. My new car has a built-in DAB radio and I have it permanently set to DAB for preference, it's extremely good almost all the time, prefer it to FM.

[Roger Provins 2Participant @rogerprovins2]

I live in an area with superb DAB reception. all the signal bars are at maximum without an external aerial, unfortunately since my Pure Evoke 3 broke (and no one will fix it) I don't have a DAB receiver. With internet radio I can't see me buying another and if I did it most certainly wouldn't be a Pure after their total lack of help – even communication.

Rog

Edited By Roger Provins 2 on 11/01/2016 16:15:30

[Roger Provins 2Participant @rogerprovins2]

I used to listen to the Test matches, all day long, on the LW. Do they still do that?

[modeng2000Participant @modeng2000]

Should I sell my Pure Evoke 3 while it is still working?

[Roger Provins 2Participant @rogerprovins2]

Dunno, all I can say is it's a bin job if it stops. I couldn't get mine repaired anywhere.

[Michael GilliganParticipant @michaelgilligan61133]

[slightly off-topic]

I haven't auditioned it seriously yet, but this is BBC Radio 3 streaming in AAC at 320

AND it appears to run fine on my v1 iPad with iOS 5.1.1

… Happy Days …

MichaelG.

.

For those with other tastes; here is the UK page.

Edited By Michael Gilligan on 11/01/2016 20:28:47

[Ian S CParticipant @iansc]

Got my single valve,regen set working last night for about the first time in twenty years, plenty of NZ stations, and some Australian ones, didn't ID those ones, it was getting a bit late.

Ian S C

Edited By Ian S C on 12/01/2016 09:46:00

[Gordon TarlingParticipant @gordontarling37126]

For the life of me, I don't know why we didn't adopt the US satellite radio system. It was just brilliant when I used it in a car while on holiday a couple of years ago. Anyway, Internet radio is the way to go in poor FM/DAB reception areas. If you don't have an internet connection in your workshop, a pair of 'Homeplugs' works well and is very easy to get working – that's what I'm using and the workshop is around 25m from the house.

[Johnboy25Participant @johnboy25]

Roger… Don't you know any local tame Electronic Engineers? I'd start with checking the power supply. BTW I hate trying to fixe Switch Mode Power Supplies – I usually do the smoke test looking for burnt component first – I can detect a burnt component by its smell at ten paces! 😳

[Phil WhitleyParticipant @philwhitley94135]

My DAB radio in the kitchen was pretty good till you opened the fridge door, then no signal!, then it packed up just out of warranty, so I binned it and went back to VHF. Advantage with VHF is that in poor weather you get a slight backgound hiss, whereas with dab you cannot listen to it! One of the main reasons for the introduction of DAB is the huge power saving at the transmitters. Dab radios should be MUCH cheaper than analogue radios, because they are much cheaper to make, being all present on a single chip!! Now that the DAB revolution has whimpered itself to death, and all those promised thousands of stations are never going to happen, there really isnt much point unles you happen to live in a spectacular reception area. Also seen a lot of problems reported with Dab car radios. They aren't going to turn VHF off any time soon!

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