Is there a relay transmitter in the dartford tunnel? I assume there must be
since some stations remain clear even in the centre but how come only some
work? Heart is clear , LBC disappears into static about 100 metres in. Do the
stations have to pay a fee to be re-broadcast?

B2003

In message , d
writes

Is there a relay transmitter in the dartford tunnel?

Yes

I assume there must be since some stations remain clear even in the
centre but how come only some work? Heart is clear , LBC disappears
into static about 100 metres in. Do the stations have to pay a fee to
be re-broadcast?

I think they do, which is why only some stations are clear (Radio 4 LW
always seems to work, and I think Five Live on MW, amongst others. There
is also a feed through the tunnel for some mobile phone services.

--
Paul Terry

On Wed, 17 Feb 2010 10:17:40 +0000
Paul Terry wrote:
I assume there must be since some stations remain clear even in the
centre but how come only some work? Heart is clear , LBC disappears
into static about 100 metres in. Do the stations have to pay a fee to
be re-broadcast?

I think they do, which is why only some stations are clear (Radio 4 LW
always seems to work, and I think Five Live on MW, amongst others. There

I wonder how they prevent interference near the portals between the relays
and the main signal? The station I was listening to on FM transitioned
smoothly.

B2003

On 2010-02-17 09:46:38 +0000, d said:

Is there a relay transmitter in the dartford tunnel? I assume there must be
since some stations remain clear even in the centre but how come only some
work? Heart is clear , LBC disappears into static about 100 metres in. Do the
stations have to pay a fee to be re-broadcast?

B2003

They use a leaky feeder. No, I don't know the technical details..

In message , d
writes

I wonder how they prevent interference near the portals between the relays
and the main signal? The station I was listening to on FM transitioned
smoothly.

http://en.wikipedia.org/wiki/Tunnel_transmitter may help, although some
car radios can perform their own frequency shift when a signal
deteriorates.
--
Paul Terry

"Ken Wheatley" wrote in message
...
On 2010-02-17 09:46:38 +0000, d said:

Is there a relay transmitter in the dartford tunnel? I assume there must
be
since some stations remain clear even in the centre but how come only
some
work? Heart is clear , LBC disappears into static about 100 metres in. Do
the
stations have to pay a fee to be re-broadcast?

B2003

They use a leaky feeder. No, I don't know the technical details..

Yes lots of feeder and other bits.

There is a number of broadcast stations on the system
Mobile phones are carried (Although there is some debate about should it be
switched on or not)
Airwave (Police, Fire Ambulance)
Tunnel Maintenance & other PMR radio users.

Its mostly off air enhancers rather than EBTS's used although that's not the
case for all of the projects we have been involved in.

I worked on that project and many others. You can factor in the portals and
how much signal there is into the system design we had to do that for a
system I was involved with.

"Ken Wheatley" wrote in message
...
On 2010-02-17 09:46:38 +0000, d said:

Is there a relay transmitter in the dartford tunnel? I assume there must
be
since some stations remain clear even in the centre but how come only
some
work? Heart is clear , LBC disappears into static about 100 metres in. Do
the
stations have to pay a fee to be re-broadcast?

B2003

They use a leaky feeder. No, I don't know the technical details..


Probably use the same system as Sydney which has a lot of long road tunnels.
Drivers are encouraged to switch on their radios when in tunnels as the
tunnel operators can override the broadcast signal and broadcast their own
emergency message if there is a problem in the tunnel.

Peter
Sydney