[TIGHazard]

Can't remember where I read this but because the tower was instrumental in TV transmission back in the day (it probably still is) is it true its actual physical location was effectively a state secret?

en.wikipedia.org 

BT Tower - Wikipedia
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  Source: en.wikipedia.org

Due to its importance to the national communications network, information about the tower was designated an official secret. In 1978, the journalist Duncan Campbell was tried for collecting information about secret locations, and during the trial the judge ordered that the sites could not be identified by name; the tower could only be referred to as 'Location 23'.

It is often said that the tower did not appear on Ordnance Survey maps, despite being a 177-metre (581 ft) tall structure in the middle of central London that was open to the public for about 15 years. However, this is incorrect; the 1:25,000 (published 1971) and 1:10,000 (published 1981) Ordnance Survey maps show the tower. It is also shown in the London A–Z street atlas from 1984.

In February 1993, the MP Kate Hoey used the tower as an example of trivial information being kept officially secret, and joked that she hoped parliamentary privilege allowed her to confirm that the tower existed and to state its street address.

[Technologist]

Perhaps this explains it ….
blog.sciencemuseum.org.uk 

The BT Tower and a classified communications network - Science Museum Blog
What connects the microwave ovens we have in our homes to the classified locatio…
  Source: blog.sciencemuseum.org.uk

We have Kate Hoey MP. To thank for making it public

[Bluecortina]

x

Perhaps this explains it ….
blog.sciencemuseum.org.uk 

We have Kate Hoey MP. To thank for making it public

I wonder what happened to the new 435 line colour television system!

The tallest building in London from 1956!

[Omnipresent]

This is hugely symbolic given the tower's role in modern communications. I used to work nearby and you'd never walk past without looking up at it. I hope the new owners keep the scrolling screen.

I suspect converting the tower into a hotel will not be cheap and, if other conversions in London are anything to by, the rooms will be priced way out of the league of most.

[harshy]

I’d love to work at bt tower with all those connectivity lines coming in from all over the world, the stuff of dreams :-)

[Stooky Bill]

Can't remember where I read this but because the tower was instrumental in TV transmission back in the day (it probably still is) is it true its actual physical location was effectively a state secret?

Not just TV, it was the centre of the Post Office's microwave network so carried inter-city telephone calls as well as television. The telephone network was probably considered the more important traffic.
www.dgsys.co.uk 

London (BT Tower): BT Microwave Sites
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  Source: www.dgsys.co.uk

It was built on the Museum telephone exchange, which is still there
www.dgsys.co.uk 

London (Museum TE): BT Microwave Sites
Menu Skip to content Map of Sites Main Routes London to Birmingham Television Li…
  Source: www.dgsys.co.uk

The tower itself isn't used for much any more, all the dishes and horns are gone and although there's still some aerials on it they're localised transmissions.... there's a DAB transmitter on the roof for example.

It's what goes on in the buildings at the base which is important and this is what is referred to as the tower operationally. When you need to contact BT for a switch you phone 'the tower', the colour bars have 'BT Tower' on them.... but that's nothing to do with the actual tower.

BT still has a role in television, most big TV facilities have 'local end' connections to and from Tower and BT provides the contribution networks for both the BBC and ITV. That wasn't always the case, BT only got the contract with the BBC about 6 or 7 years ago.

However these days these are big MPLS fibre networks, so although the control system and people you phone are possibly based in Tower the route the data will take probably goes nowhere near it. IP changes everything, hence once the traditional phone network goes next year there'll be need for a lot of their exchanges.... It's all in the 'cloud'

Since deregulation in the 80s you don't have to use BT to get video, audio or data from a to b. Arqiva have their own network, Globecast do a lot of TV connectivity and telecoms companies like Vodafone and Virgin Media have large networks. The advantage with BT is that they through Openreach have fibre presence literally everywhere as a legacy of the old monopoly days.

[simpfeld]

The tower itself isn't used for much any more, all the dishes and horns are gone and although there's still some aerials on it they're localised transmissions.... there's a DAB transmitter on the roof for example.

Walking past it this morning there still seem to be a fair number of small microwave dishes much higher up than old old horn levels (above the rotating sign level). Anyone know what these are for?

[Technologist]

They are the outside broadcast radio links ….. still used despite fibre 4/5 G and satellite .
These are rigged for each programme/ booking
so long as you are not working with wind speed higher than 40 mph.
They are often in the 11Ghz band ….

[i.h]

They are the outside broadcast radio links ….. still used despite fibre 4/5 G and satellite .
These are rigged for each programme/ booking
so long as you are not working with wind speed higher than 40 mph.
They are often in the 11Ghz band ….

worth adding that it is probably the next best thing to fibre, given that it operates in licenced spectrum (should be no surprise sources of interference), provides a much better guarantee of performance compared to cellular, and does not have the latency / cost concerns that come with satellite.

you still see a lot of microwave links on cell sites for this reason. in rural areas they might run fibre to a "hub" site and use microwave to get to more remote sites where fibre would be expensive or impractical.

the aforementioned website suggests that a microwave link between Cornwall and the Isles of Scilly is still in use despite a fibre being rerouted there a few years ago as part of broadband upgrades. Presumably retained as a backup in case something hits the cable.

[thegeek]

However these days these are big MPLS fibre networks, so although the control system and people you phone are possibly based in Tower the route the data will take probably goes nowhere near it. IP changes everything, hence once the traditional phone network goes next year there'll be need for a lot of their exchanges.... It's all in the 'cloud'

The point-to-point 'local end' product still exists. For most of the last decade it was based on Nevion media converters and CWDM, so you could fit four 3G video services (in each direction) on a single fibre. They were in the process of replacing them at my previous workplace, and I was under the impression it was just a newer Nevion product (using TICO compression) on the same bits of fibre, though I didn't get a chance to properly investigate it before they got ceased.

The MPLS network is obviously a bit easier to relocate!