DAB radio

Trev

The Dumb One
I know 'we' are a Humax based forum but I was just wondering whether anyone here has DAB experience.
At the moment I am running my, now broken, FM radio using a 'T' of 300 ohm feeder pinned to the picture rail. When it was working, this was fine.
I am toying with the idea of getting a DAB/FM tuner device, and wondered whether there is any expertise WRT DAB indoor aerials and, if outdoor is required, how to combine and split the signal down one co-ax.?
Any takers please.
 

gomezz

Well-Known Member
My living room DAB radio is fed from my TV aerial. I suspect it is the downlead rather than the aerial which is picking up better reception that that from the original whip aerial.

The other option is to use your Humax box to listen to the radio.
 

Black Hole

May contain traces of nut
It all depends how good the signal coverage is in your area. I only routinely use DAB in the car, which uses a windscreen-mounted dipole, and I get LOS in central Newport and over Salisbury Plain. I have a DAB clock-radio with a length of thin wire as an antenna and seems to work perfectly well even in a not-very-good location in the house. I also have a Pure portable DAB radio with a telescopic antenna, which again works perfectly well (I bought that for Madam to avoid the retuning that is needed with an analogue set when there is a conductive body in the vicinity of a whip aerial).

The only really negative experience was with a personal unit with headphones for listening and as the antenna (and I can't remember what it was or what's happened to it), which proved unsatisfactory when working around the house and garden so I carried on with FM - but that was in the early days of DAB and coverage is probably better now.

I used to be anti-FMSO and saw the push to DAB as a Trojan horse, but as I understand it the FM network is coming to the end of its service life and will need major investment to renew it so I think the money would be better spent on expanding DAB. I think FM is still useful, because it is longer range and there are still a hell of a lot of cars that are not DAB capable, but when I wanted to upgrade my car audio I considered it foolish not to buy DAB for future-proofing (even though it significantly reduced my options at the time).
 

ian_j

Member
Years ago I made a "slim jim" aerial to replace the standard telescopic aerial on a Pure Evoke radio, I still use it today and get excellent reception from it.

I don't know if this is the exact instructions I used but this is the same construction as mine, I just changed the dimensions to match DAB:

https://radio.xtreamlab.net/omni-aerial.html
 
OP
Trev

Trev

The Dumb One
Thanks for the info guys. I suspect I will start off with the well known bit of damp string, and work up 'till it works OK.
 

Scrat

Definitely contains acorns
Strange thing. My car dab radio volume fades in low signal areas. I have no DSP enabled, but it fades with volume boost too. I thought this was exactly what dab did not do.
 

keithatrochdale

Super Moderator
Staff member
I am a firm FM lover, why - because it is better quality.

If you start looking at the bit rate of DAB it can be good, but a lot of stations are low bit rate - would it be fair to suggest that there was the chance to make more money by lowering the bit rate and cramming in more stations at a very nice fee!

Also the coverage is not good and it can be badly effected by bad weather.

I can see FM continuing long into the future, remember how long 405 line tv went on despite many scare stories that if would stop.
 

Black Hole

May contain traces of nut
Strange thing. My car dab radio volume fades in low signal areas. I have no DSP enabled, but it fades with volume boost too. I thought this was exactly what dab did not do.
I don't understand how that might be - it's a digital signal, so suffers the digital cliff. My car audio has a mode (I keep switched off) that falls back to FM - could it be that (but on the other hand, FM doesn't fade either)?
 

Scrat

Definitely contains acorns
Also the coverage is not good and it can be badly effected by bad weather.


whoops :lol:
 

Scrat

Definitely contains acorns
I don't understand how that might be - it's a digital signal, so suffers the digital cliff. My car audio has a mode (I keep switched off) that falls back to FM - could it be that (but on the other hand, FM doesn't fade either)?
It makes no sense to me either. The display still shows dab, not fm. Is that what you see?
 
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Scrat

Definitely contains acorns
Mine is an OEM Toyota, but switching and not telling you might explain it if the volume levels of dab and fm are different. I will check that out. Thanks for that, I never knew they could do that.

Another possibility is that the sound mutes to avoid loud bangs and crackles.
 

Black Hole

May contain traces of nut
Assuming that's it, mine has a source level adjustment to try to equalise volume levels (we know that's fraught with difficulty, but at least the menu option is there unlike on a Humax!).
 

Black Hole

May contain traces of nut
I had a little play today; the menu setting on mine is Tuner >> DAB AF >> DAB AF ON. The result is the car radio switching to the FM station with the same channel ident if the signal is lost on DAB (with no obvious sign on the display, other than "AF" to show that the mode is active).
 

Scrat

Definitely contains acorns
I had a little play today; the menu setting on mine is Tuner >> DAB AF >> DAB AF ON. The result is the car radio switching to the FM station with the same channel ident if the signal is lost on DAB (with no obvious sign on the display, other than "AF" to show that the mode is active).
I had a play with mine too. Switching betwen dab and fm gave the same volume setting to my ears. However, there is an alternative frequency toggle, I assume that is what your AF is, so I will investigate further, possibly tomorrow.

I didn't see any source level adjustment, but will search around.
 

Black Hole

May contain traces of nut
Switching betwen dab and fm gave the same volume setting to my ears.
Maybe so when both signals are OK, but when I went through a poor signal area for DAB it was also a poor signal area for FM so suffered noise and drop-outs on that when it switched over.
 

Scrat

Definitely contains acorns
I watched the dab display. Hardly any of the reception was dab. When dab went off, about 5 miles from home, FMlink appeared. I assume that meant I was listening to FM. Dab returned when I was 5 miles from home. Apart from that, FMlink regularly disappeared from view and then there was no sound at all.

Inconclusive, really, but thanks to you I now know roughly what is happening. I had no idea about the band switching!
 

MikeSh

Well-Known Member
It makes sense really. We've had AF on FM for donkey's years and making it work across DAB & FM is probably trivial. (I assume AF works either by finding the station indent or looking at a list of alternative 'frequencies' transmitted as part of the info stream.)

I haven't tested this function yet but on my car the saved stations are all saved in one list, DAB/FM all together, so it may work. I currently have separate FM and DAB saves for some stations, but maybe I only need one of them and the AF will pick the best available. Interesting.

That said, I think I may have turned AF off because one trip it kept flipping to a different station - presumably a sister to the one I was listening too.
 

Scrat

Definitely contains acorns
So my conclusion is that the radio switches fro dab to fm using the ident, but fails on fm when the fm signal is weak. On the same journey in a previous car, the fm only receiver would have switched frequencies several times. This clearly doesn't.

I have no idea about the fading I previously experienced, but the unit recently had a firmware update, so it may have been a bug, the dab and fm volumes not being matched.

If only I had one list of stations! There is an fm list, but on dab, just a service list for each carrier! Why on earth would anyone think that a good idea? With only 6 dab favourites, it makes finding any other station a nightmare.
 
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