Is A Sharkfin Aerial Suitable For Dab On An 07 Ls460?

[derryuk]

I started listening to mobile DAB about 8 years ago, first on a Scenic then a Rav4. The Scenic was mostly OK and would drop out once in my locale, the Rav4 was faultless with no dropout locally. On the DAB reception map http://www.ukdigitalradio.com/coverage/postcodesearch/ my locale is listed as “fair reception”. I’ve decided to fit DAB to my 07 LS460.

I’ve chosen the Alpine Ezi-DAB http://www.alpine.co.uk/p/Products/dab3842/ezi-dab head unit and controller with a sharkfin aerial http://www.dabonwheels.co.uk/DAB_car_aerials.html suggested by my installer. He will fit the kit in a couple of days. I wouldn’t choose a sharkfin aerial as first choice as they look all wrong to me for DAB/FM but most upmarket cars use them.

So while thinking of life one day it occurred to me that I could compare the sharkfin to a DAB dipole http://www.aerialsandtv.com/fmanddabradio.html#FMandDABaerialTests for reception. I have a dipole in my computer room hanging on the curtain rail connected to a Teac receiver. This shows signal strength of 15 digits for 5live.

I mounted the sharkfin on the side of an old pc case to represent a car roof, not a true representation but better than nothing. When I connected the sharkfin to the Teac it showed signal strength of 13 – 14 digits for 5live depending on which way it was pointing. The sharkfin has a 12v amplifier in its body and with no power there is no signal.

Bear in mind I have no idea what 13 digits means compared to 15. If the scale is logarithmic 13 might mean next to nothing while 15 is good.

So on the face of it it looks reasonable. I’ll be interested to see if I get the same drop out as I did with the Scenic. I’ll post the results here later in the week.

Derry.

[derryuk]

Install done though it took a while. I've been out on my usual run where my old Sceninc DAB used to drop out for about quarter of a mile and with the EZi-DAB there was just the briefest of drop-outs so I'd rate it a success.

The installation is very neat with no loose cables.

Complaints: (so far)

There is no FM for some reason and the installer didn't know why. However since I have not listened to FM for the last 6 years and one day it will be switched off (allegedly) this isn't a problem.

Derry.

http://s692.photobucket.com/user/Derryuk/media/IMG_08121.jpg.html?sort=3&o=0

http://s692.photobucket.com/user/Derryuk/media/IMG_08091.jpg.html?sort=3&o=1

[Connoisseur]

Looks a great instal. I put the EZI DAB into my GS using a glass mount telescopic aerial from dabonwheels; reception has been consistently good and I find the unit straightforward to use. The dabonwheels site offers a lot of useful advice and info.

in case it helps EZI DAB is purely a DAB unit and doesn't offer any FM service.

Regards

M

[derryuk]

Accepted. I should add that my comment about lack of FM referred to the FM feedthrough option on the EZI-DAB. AIUI with the EZi-DAB switched off the unit should feed through a signal from the car aerial for FM.

On the main unit:

connector 8 is DAB aerial in - my sharkfin DAB connected here

connector 7 is FM aerial in - my sharkfin FM connected here

connector 6 is antenna out for direct inject - this is connected to my Lexus radio FM aerial in.

My uncertainty comes from the installer settings. One is antenna iput source:

connector 8 (powered) - my sharkfin is externally powered so I don't need this

connectot 8 (unpowered)

connector 7 - I am not sure why this option is here

I have tried all three options and all I get is DAB.

More uncertainty comes with the FM pass-through options which are: (in their words)

disabled - ezi-dab output effectively replaces all FM stations when ezi-dab is switched on (default)

enabled - ezi-dab output is blended in to the FM waveband alongside normal broadcast FM stations.

I have tried both and only ever get DAB with the unit on and FM noise only with it off. My current thinking is perhaps my sharkfin isn't producing any FM for some reason.

Derry.

[derryuk]

OK, I have changed my mind about the sharkfin. Today I drove through my local patch of poor reception for the second time and DAB reception was very poor, as bad as my old Scenic so I rerate the sharkfin DAB reception as mediocre. The change in performance is brought about I guess by a change in the weather. I know with FM you get better reception with high pressure, I don't know how it affects DAB though

Now then although my Scenic was mediocre my Rav4 had very good DAB reception (whip aerial mounted ar the roof rear) with no dropout in my poor recption area at all for the year that I owned it. I'm toying with fitting a Hirschmann AUTA 16 V DAB to the 460.

Derry.

[derryuk]

Ignore my previous, the poor reception was due to finger trouble (sigh).

I had received an email answer from Alpine re my lack of FM reception. No solutions sadly but I thought I would have a play with the ezi-DAB settings. One option I had previously eneabled was FM aerial in (input 7) in my attempt to get an FM signal on my Lexus radio. I renabled input 8 (DAB only) and I noticed the signal strength shoot up! (one option is to display station name and signal strength.) So I drove back through my poor DAB reception route and the signal was perfect again!

So my previous poor reception was due to seemingly me using the FM aerial for DAB.

BTW the answer from Alpine was that FM pass-trough is only enabled with the ezi-DAB switched off. Sadly to say not in my case it isn't.

Derry.

[abs66]

Pardon my ignorance, do Lexus offer a retrofit DAB module or something for the 460 like BMW, (sorry for swearing!),do for older models?

I am a fan of DAB for 5 Live and 4 Extra if nothing else and it seems a shame to have to stick an aftermarket unit on a reasonably modern car, even if it is nice quality like the Alpine.

Cheers

Pete

 

[Cotswold Pete]

Derry,

Really surprised the Fin works so well.  DAB needs an aerial of around 30 to 40cm length to pick up the most of any signal in the ether.

However where signals are strong then less than 30cm will work.  I assume that if you replaced Fin with the Hirschmann, then you would be able to pick up more multiplexes especially when driving out in the wilds of nowhere, or even in the middle of London, where the tall buildings block DAB way too much.

 

 

[derryuk]

Agreed. Don't forget the shark-fin I used had an RF amplifier and you can probably squeeze more usable digital signal with one than say an FM/AM signal.