DAB signal in North Norfolk
 

In message , David Looser
writes
"Ian Bell" wrote in message
...
tony sayer wrote:
In , Brian Gaff
scribeth thus
Its probably being killed by signals from all over europe and it will
get
back to normal when the high pressure puts things back to normal.
Brian


Theres always FM;)...


There's no Radio 7 on FM, more's the pity.


If there was a problem with "signals from all over europe" it'd affect FM
far more than it would DAB.

And Radio 7 is on the internet and on Freesat.

There are two 'modes' which are responsible for long-distance
propagation on VHF and UHF.

One is Sporadic-E propagation. The E-layer is the lowest of the
reflecting layers in the ionosphere (about 100 miles up), and is
activated by sunspot activity. Compared with the other layers, it is
very spasmodic and transient, and mainly occurs in daytime in late
spring and early summer. [It's a bit late in the year for significant
Sporadic-E]. It affects essentially only in the range 25 to 150MHz, and
can enable the reception of very strong Band 2 FM radio signals from
distances of up to 1000 miles. It doesn't affect Band 3 (DAB) or UHF TV.

The other mode is tropospheric ducting, which is occurs when the
temperature gradient in the atmosphere becomes inverted. The radio waves
get trapped in a duct, which is typically only 5 or 10 miles up, and get
bent around the curvature of the Earth, landing typically 500 to 1000
miles away. This happens mainly in calm, fine weather, when there is a
large, stable area of high pressure sitting stationary (particularly
over a warm sea). This is what we have at the moment. It can affect Band
3, but it is most prominent at UHF.
--
Ian

DAB signal in North Norfolk
 

In article , David Looser
wrote:
"Ian Bell" wrote in message
...
tony sayer wrote:
In , Brian Gaff
scribeth thus
Its probably being killed by signals from all over europe and it
will get back to normal when the high pressure puts things back to
normal. Brian


Theres always FM;)...


There's no Radio 7 on FM, more's the pity.


If there was a problem with "signals from all over europe" it'd affect
FM far more than it would DAB.

That rather depends on the details of what is causing the changes in
propagation, where you live, etc. Bear in mind this isn't simply a matter
of frequency. Also a matter of the DAB TXs being lower powered and relying
on the RX being able to use the modulation methods employed to get a good
reception from a much poorer CNR at the RX than would be OK for FM.

FWIW last night my R4 FM reception deteriorated to the point of being
unlistenable. So FM reception here has certainly been varying recently.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

DAB signal in North Norfolk
 

"Jim Lesurf" wrote in message
...
In article , David Looser
wrote:
"Ian Bell" wrote in message
...
tony sayer wrote:
In , Brian Gaff
scribeth thus
Its probably being killed by signals from all over europe and it
will get back to normal when the high pressure puts things back to
normal. Brian


Theres always FM;)...


There's no Radio 7 on FM, more's the pity.


If there was a problem with "signals from all over europe" it'd affect
FM far more than it would DAB.

That rather depends on the details of what is causing the changes in
propagation, where you live, etc. Bear in mind this isn't simply a matter
of frequency. Also a matter of the DAB TXs being lower powered and relying
on the RX being able to use the modulation methods employed to get a good
reception from a much poorer CNR at the RX than would be OK for FM.


Yes, I accept all that, I was trying to keep things simple. I was responding
to the claim that: "Its probably being killed by signals from all over
europe". It seems to me unlikely in the extreme that Ian's DAB reception is
being affected in the way he says it is (low signal strength) by "signals
from all over Europe".

David.

DAB signal in North Norfolk
 

In article , David Looser
wrote:
"Jim Lesurf" wrote in message
...


If there was a problem with "signals from all over europe" it'd
affect FM far more than it would DAB.

That rather depends on the details of what is causing the changes in
propagation, where you live, etc. Bear in mind this isn't simply a
matter of frequency. Also a matter of the DAB TXs being lower powered
and relying on the RX being able to use the modulation methods
employed to get a good reception from a much poorer CNR at the RX than
would be OK for FM.


Yes, I accept all that, I was trying to keep things simple. I was
responding to the claim that: "Its probably being killed by signals
from all over europe". It seems to me unlikely in the extreme that
Ian's DAB reception is being affected in the way he says it is (low
signal strength) by "signals from all over Europe".

OK.

FWIW I wonder if with DAB this might be a case where an SFN causes more
trouble than would afflict traditional broadcasts... :-)

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

DAB signal in North Norfolk
 

Jim Lesurf wrote:
In , David Looser
wrote:
"Jim wrote in message
...


If there was a problem with "signals from all over europe" it'd
affect FM far more than it would DAB.

That rather depends on the details of what is causing the changes in
propagation, where you live, etc. Bear in mind this isn't simply a
matter of frequency. Also a matter of the DAB TXs being lower powered
and relying on the RX being able to use the modulation methods
employed to get a good reception from a much poorer CNR at the RX than
would be OK for FM.


Yes, I accept all that, I was trying to keep things simple. I was
responding to the claim that: "Its probably being killed by signals
from all over europe". It seems to me unlikely in the extreme that
Ian's DAB reception is being affected in the way he says it is (low
signal strength) by "signals from all over Europe".

OK.

FWIW I wonder if with DAB this might be a case where an SFN causes more
trouble than would afflict traditional broadcasts... :-)

Slainte,

Jim



Whatever the reason, normal service seems now to have resumed and the wife is
happy listening to Radio 7 again in the kitchen.

Cheers

Ian