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DAB aerial



 
 
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  #31 (permalink)  
Old January 23rd 08, 09:42 AM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Andy Burns
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Posts: 2
Default DAB aerial

On 21/01/2008 19:21, Mark Carver wrote:

I've always used my vertical Band II (aka FM band) dipole
for DAB, it works very well, pulling in distant muxes from miles away.


If you pull in distant (i.e. over 46 miles) signals won't that harm the
BBC SFN signal from your local TX? also you'll just get "n" copies of
Gold/Chill/Galaxy/Heart/Traffic/XFM


  #32 (permalink)  
Old January 23rd 08, 06:06 PM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Mark Carver
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Posts: 23
Default DAB aerial

Andy Burns wrote:
On 21/01/2008 19:21, Mark Carver wrote:

I've always used my vertical Band II (aka FM band) dipole for DAB, it
works very well, pulling in distant muxes from miles away.


If you pull in distant (i.e. over 46 miles) signals won't that harm the
BBC SFN signal from your local TX?


No, the local BBC/D1 transmitter's signal is about 30dB up on any of the
distant ones.

also you'll just get "n" copies of
Gold/Chill/Galaxy/Heart/Traffic/XFM


Yes I do, I just ignore them.

--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #33 (permalink)  
Old January 23rd 08, 06:49 PM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Bill Wright
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Posts: 25
Default DAB aerial


"Mark Carver" wrote in message
...
Andy Burns wrote:
On 21/01/2008 19:21, Mark Carver wrote:

I've always used my vertical Band II (aka FM band) dipole for DAB, it
works very well, pulling in distant muxes from miles away.


If you pull in distant (i.e. over 46 miles) signals won't that harm the
BBC SFN signal from your local TX?


No, the local BBC/D1 transmitter's signal is about 30dB up on any of the
distant ones.

also you'll just get "n" copies of Gold/Chill/Galaxy/Heart/Traffic/XFM


Yes I do, I just ignore them.


As a matter of fact I did a job today in a village called North Wheatley,
out near Gainsboro somewhere. The house was in a bit of a dip and the
resident had a portable DAB radio that couldn't find a station. The building
is listed so the best I could do was a loft aerial. A vertical dipole cut
for 225MHz brought in four muxes at good strength.

Bill


  #34 (permalink)  
Old January 23rd 08, 07:37 PM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Marky P
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Posts: 47
Default DAB aerial

On Wed, 23 Jan 2008 10:15:11 +0000, tony sayer
wrote:

In article , Bill Wright
scribeth thus

"Doctor D" wrote in message
...
I bought one and pointed it due north from my location about 30 miles
south of Sutton Coldfield. It's very good, bringing in about 100 channels
(some duplicates) but also stations from Shropshire and beyond, for which
we are well outside the service area.

The Birmingham stations are all "off the scale" whereas previously on the
internal rod antenna they weren't even being decoded.


Interesting.

Bill



Not really. The difference an outside aerial makes from an indoor bit of
wire is very significant. A while ago I was playing about with a Denon
tuner in a Suffolk town not renowned for its signals, even mobile which
can be quite good. An ordinary vertical FM di-pole @ 10 MAGL made the
band come alive!..

If everyone were to use the right aerial then we could drop the ERP's by
a lot and therefore "save the planet" i.e. bailing out the titanic with
a teaspoon!...


I also found that slighly moving a DAB aerial can make or break
reception. I was getting nothing on Cambridge DAB, then I moved the
DAB aerial down the mast about 12 inches and signal shot up to 80%.

Marky P.

  #35 (permalink)  
Old January 23rd 08, 08:09 PM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Andy Hall
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Posts: 8
Default DAB aerial

On 2008-01-23 20:37:00 +0000, Marky P said:

I also found that slighly moving a DAB aerial can make or break
reception. I was getting nothing on Cambridge DAB, then I moved the
DAB aerial down the mast about 12 inches and signal shot up to 80%.

Marky P.


Remember that it's the signal quality as opposed to the strength that
matters. The two don't always correlate.




  #36 (permalink)  
Old January 23rd 08, 10:26 PM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Dave Plowman (News)
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Posts: 5,872
Default DAB aerial

In article ,
Andy Burns wrote:
I've always used my vertical Band II (aka FM band) dipole
for DAB, it works very well, pulling in distant muxes from miles away.


If you pull in distant (i.e. over 46 miles) signals won't that harm the
BBC SFN signal from your local TX? also you'll just get "n" copies of
Gold/Chill/Galaxy/Heart/Traffic/XFM


IIRC, it's a feature of DAB that receiving a second signal from a
different transmitter can be a benefit as it adds to the original -
rather causing multipath problems as with FM.

--
*If Barbie is so popular, why do you have to buy her friends? *

Dave Plowman London SW
To e-mail, change noise into sound.
  #37 (permalink)  
Old January 23rd 08, 10:33 PM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Don Pearce
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Posts: 1,822
Default DAB aerial

On Wed, 23 Jan 2008 23:26:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Andy Burns wrote:
I've always used my vertical Band II (aka FM band) dipole
for DAB, it works very well, pulling in distant muxes from miles away.


If you pull in distant (i.e. over 46 miles) signals won't that harm the
BBC SFN signal from your local TX? also you'll just get "n" copies of
Gold/Chill/Galaxy/Heart/Traffic/XFM


IIRC, it's a feature of DAB that receiving a second signal from a
different transmitter can be a benefit as it adds to the original -
rather causing multipath problems as with FM.


Up to a point. There is a guard interval that allows multipath signals
up to a certain amount of delay (hence distance). I can't remember
what that distance is, but I know it is less than it would have been
if they hadn't gone for the "available now" option, but waited for the
chip sets that permitted more, slower carriers.

d

--
Pearce Consulting
http://www.pearce.uk.com
  #38 (permalink)  
Old January 23rd 08, 10:58 PM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Andy Burns
external usenet poster
 
Posts: 2
Default DAB aerial

On 23/01/2008 23:33, Don Pearce wrote:
On Wed, 23 Jan 2008 23:26:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

IIRC, it's a feature of DAB that receiving a second signal from a
different transmitter can be a benefit as it adds to the original -
rather causing multipath problems as with FM.


Up to a point. There is a guard interval that allows multipath signals
up to a certain amount of delay (hence distance). I can't remember
what that distance is,


The guard interval for DAB is 246 microseconds, hence
http://google.com/search?q=c+*+246+m...conds+in+miles
  #39 (permalink)  
Old January 24th 08, 12:35 AM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Bill Wright
external usenet poster
 
Posts: 25
Default DAB aerial


"Andy Burns" wrote in message
...
On 23/01/2008 23:33, Don Pearce wrote:
On Wed, 23 Jan 2008 23:26:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

IIRC, it's a feature of DAB that receiving a second signal from a
different transmitter can be a benefit as it adds to the original -
rather causing multipath problems as with FM.


Up to a point. There is a guard interval that allows multipath signals
up to a certain amount of delay (hence distance). I can't remember
what that distance is,


The guard interval for DAB is 246 microseconds, hence
http://google.com/search?q=c+*+246+m...conds+in+miles


Given that the 46 miles is the difference between path lengths I would have
thought it was more than adequate.

Bill


  #40 (permalink)  
Old January 24th 08, 04:38 AM posted to uk.d-i-y,uk.rec.audio,uk.tech.broadcast
Don Pearce
external usenet poster
 
Posts: 1,822
Default DAB aerial

On Thu, 24 Jan 2008 01:35:29 -0000, "Bill Wright"
wrote:


"Andy Burns" wrote in message
...
On 23/01/2008 23:33, Don Pearce wrote:
On Wed, 23 Jan 2008 23:26:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

IIRC, it's a feature of DAB that receiving a second signal from a
different transmitter can be a benefit as it adds to the original -
rather causing multipath problems as with FM.

Up to a point. There is a guard interval that allows multipath signals
up to a certain amount of delay (hence distance). I can't remember
what that distance is,


The guard interval for DAB is 246 microseconds, hence
http://google.com/search?q=c+*+246+m...conds+in+miles


Given that the 46 miles is the difference between path lengths I would have
thought it was more than adequate.

Bill


Most of the time yes, but I've studied an awful lot of anomalous
propagation over the years and particularly around sunset it is not
unusual to get signals coming through from much further at high
strength for a few seconds.

d

--
Pearce Consulting
http://www.pearce.uk.com
 




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