Misleading advert in Radio Times

On Thu, 08 Apr 2010 15:15:10 +0100, Graham. wrote:

I'm not sure I would particularly welcome 100s of kilowatts of RF
close to my server-room.

Servers being rather heavy machines tend to be located on the sub-street
level floors not on the 99th floor below the transmitters.

So are there many servers on the upper floors of 1 Canada Place?

Were there problems with the transmitters on top of the World Trade Center
or now on the Empire State Building interfering with computers in the building?

On Thu, 08 Apr 2010 16:11:46 +0100, Graham. wrote:

It used to be a common sight.

Was this due to the high levels of anti-social behavior of
certain members of society going around snapping off the
telescopic antennas of those who could afford to operate
their own personal transportation vehicle?

On Thu, 08 Apr 2010 14:57:52 +0200, J G Miller
wrote:

On Thu, 08 Apr 2010 02:14:08 -0700, Mike wrote:

Sat here at work I can turn my eyes 10 degrees to the left and see
Crystal Palace looking like the Eifel Tower on a diet poking its head
over the whole of the south east. Quite a sight.

If I may ask a question to those who have the knowledge about VHF and UHF
transmission and reception conditions in Greater London and environs.

Would there be better reception coverage and less multipath
problems *if* it were possible to close down the Crystal Palace
transmitter site, and move all the transmitting antennas to
a mast on top of 1 Canada Square, LB of Tower Hamlets?

To achieve the same antenna height as CP, such a mast would need to be
200 feet high. I doubt that would be achievable unless it was designed
into the structure before it was built.

Due to its proximity to the flight paths for Heathrow and City
airports, there may be EMC problems for aircraft systems. Certainly
the CAA would be *very* cautious.

And could this result in some relays in Greater London no longer
being necessary?
Probably not. But some of the relays would need to be in different
places

J G Miller wrote:

On Thu, 08 Apr 2010 16:11:46 +0100, Graham. wrote:

It used to be a common sight.

Was this due to the high levels of anti-social behavior of
certain members of society going around snapping off the
telescopic antennas of those who could afford to operate
their own personal transportation vehicle?

Maybe but the old telescopic aerials were very easy to break, accidentally
or deliberately and, if wing mounted, were easy to get to.

Snapping them used to be a popular activity even in America where almost
everyone has a "personal transport vehicle". I've never understood the
attraction though.

The modern roof mounted springy type are almost indestructible in comparison
and one would probably cut your hand before it would break off.

--
Steve Hayes, South Wales, UK
----Remove colours from reply address----

On Thu, 08 Apr 2010 17:35:10 +0100, Nemo explained:

To achieve the same antenna height as CP, such a mast would need to be
200 feet high.

Is that because Crystal Palace transmitter mast is built on a hill?

The height of Crystal Palace transmitter mast is 195Â*metres and that of
One Canada Square is 235Â*metres (40 metres taller).

Due to its proximity to the flight paths for Heathrow and City
airports

I understand your concern about City airport, but I thought flights
for Heathrow had long since been banned from coming anywhere near
One Canada Square and their previous route along the Thames?

Probably not. But some of the relays would need to be in different
places

Was the Alexandra Palace UHF transmitter commissioned because of One
Canada Square blocking off signals to more northerly areas, or was it
for other reasons?

On Thu, 08 Apr 2010 18:04:16 +0100, Steve Hayes wrote:

Maybe but the old telescopic aerials were very easy to break,
accidentally or deliberately and, if wing mounted, were easy to get to.

This was probably why they introduced the more "advanced" models with
a motor which caused the antenna to retracted.

Snapping them used to be a popular activity even in America where almost
everyone has a "personal transport vehicle". I've never understood the
attraction though.

No doubt you also heard about Rolls Royce introducing a feature to their
cars which results in the Spirit of Ectasy retracting because of people
trying to snap them off and adding them to their collection.

http://en.wikipedia.ORG/wiki/Spirit_of_Ecstasy

On Thu, 08 Apr 2010 19:20:19 +0200, J G Miller
wrote:

On Thu, 08 Apr 2010 17:35:10 +0100, Nemo explained:

To achieve the same antenna height as CP, such a mast would need to be
200 feet high.

Is that because Crystal Palace transmitter mast is built on a hill?

From memory the base of the mast is about 365 feet ASL.

The height of Crystal Palace transmitter mast is 195*metres and that of
One Canada Square is 235*metres (40 metres taller).

Due to its proximity to the flight paths for Heathrow and City
airports

I understand your concern about City airport, but I thought flights
for Heathrow had long since been banned from coming anywhere near
One Canada Square and their previous route along the Thames?

I have been on flights into Heathrow which seem to pass very close.

Probably not. But some of the relays would need to be in different
places

Was the Alexandra Palace UHF transmitter commissioned because of One
Canada Square blocking off signals to more northerly areas, or was it
for other reasons?

The Alexandra Palace relay predates that building by many years. It
fills in an area to the north which is screened from CP.

But a relay was built due to signal problems caused by the tower.

"J G Miller" wrote in message ...
On Thu, 08 Apr 2010 18:04:16 +0100, Steve Hayes wrote:

Maybe but the old telescopic aerials were very easy to break,
accidentally or deliberately and, if wing mounted, were easy to get to.

This was probably why they introduced the more "advanced" models with
a motor which caused the antenna to retracted.

Snapping them used to be a popular activity even in America where almost
everyone has a "personal transport vehicle". I've never understood the
attraction though.

No doubt you also heard about Rolls Royce introducing a feature to their
cars which results in the Spirit of Ectasy retracting because of people
trying to snap them off and adding them to their collection.

http://en.wikipedia.ORG/wiki/Spirit_of_Ecstasy
No, I thought that was a safety feature. Indeed the above link says as much.


--
Graham.

%Profound_observation%

lid wrote:

On Thu, 08 Apr 2010 19:20:19 +0200, J G Miller
wrote:

On Thu, 08 Apr 2010 17:35:10 +0100, Nemo explained:

Probably not. But some of the relays would need to be in different
places

Was the Alexandra Palace UHF transmitter commissioned because of One
Canada Square blocking off signals to more northerly areas, or was it
for other reasons?

The Alexandra Palace relay predates that building by many years. It
fills in an area to the north which is screened from CP.

And if CP was replaced by Canada Square you would need a relay at CP
to cover the area to the south of CP which would be screened from CS.

CP is simply the best place for a main transmitter for the whole
Greater London area. Moving it to a more central position creates more
problems than it solves.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

On Thu, 08 Apr 2010 18:43:12 +0100, lid wrote:

On Thu, 08 Apr 2010 19:20:19 +0200, J G Miller
wrote:

On Thu, 08 Apr 2010 17:35:10 +0100, Nemo explained:

To achieve the same antenna height as CP, such a mast would need to be
200 feet high.

Is that because Crystal Palace transmitter mast is built on a hill?

From memory the base of the mast is about 365 feet ASL.

Crystal Palace transmitter mast Site Height is 110.3m.
From:
http://tx.mb21.co.uk/gallery/crystalpalace/index.php

That makes it 361.87664 feet according to Google calculator.

The height of Crystal Palace transmitter mast is 195*metres and that of
One Canada Square is 235*metres (40 metres taller).

Due to its proximity to the flight paths for Heathrow and City
airports

I understand your concern about City airport, but I thought flights
for Heathrow had long since been banned from coming anywhere near
One Canada Square and their previous route along the Thames?

I have been on flights into Heathrow which seem to pass very close.

Probably not. But some of the relays would need to be in different
places

Was the Alexandra Palace UHF transmitter commissioned because of One
Canada Square blocking off signals to more northerly areas, or was it
for other reasons?

The Alexandra Palace relay predates that building by many years. It
fills in an area to the north which is screened from CP.

But a relay was built due to signal problems caused by the tower.

--
Peter Duncanson
(in uk.tech.digital-tv)