By

Joseph P. Campbell, HNC Marine Nav. Sys. Eng.

© FreeFoto.com

(revised 1st May 2011)

1. Levels of the 21st Century Network

2. 21CN Communications Bearers

3. Wire Pair: Parts 1, 2 and 3

4. Coaxial-Cable

5. Optical-Fibre Links

6. SHF Microwave Communications Links –Theoretical

7. SHF Microwave Communications Links – Practical: Parts 1 – 11

8. Communications Bearers: A Comparison

9. The Subscriber Line Interface Card (abbreviated to SLIC): Parts 1 – 7

10. Other Services Using The 21CN

11. The 21CN and Eavesdropping of Buildings: Parts 1 – 4

12. The 21CN and Vehicle Tracking and Monitoring

13. The 21CN and EEG Wireless Implantable Devices: Parts 1 – 3

14. The 21CN and Brainwave Emulator Implantable Devices – a form of cybernetics system: Pts. 1 – 3

15. Speech, Brainwave and Image Recognition

16. Network Management: Parts 1 – 16

17. Interception of Communications: Parts 1 – 4

18. The 21st Century Network: Synopsis

19. References: Parts 1 – 8

20. About the Presentation Author

The 21st Century Network has three different levels. These are the:

1. Access Network2. Metropolitan Network3. Core Network

The subscriber is connected to the Access Network. The Network Management Centre (NMC) is located in the Core Network. The Volumetrics * are located in both the Metropolitan & Core Networks...

*See slides 32, 33, 34 and 35 in this .pptx presentation

...The 21st Century Network uses the following bearers:

1. Wire Pair2. Optical-Fibre3. SHF Microwave Link4. Coaxial Cable

Over these four communication bearers a Time Division Multiplexed (TDM) system can be applied in order to allow the transmission of multiple channels. TDM systems superseded Frequency Division Multiplexed (FDM) systems many years ago...

...Wire Pair connections are used in the BT plc Access Network and also as part of multiplexed systems in the Metropolitan Network.

There are a number of different grades of wire pair offering different bandwidths. The bandwidth of a typical wire pair in the Access Network is about 2 MHz. Contrast this to the bandwidth of a typical telephone channel which is between 300Hz and 3400Hz...

...Because of the fact that some Government Communications Headquarters (GCHQ) microwave-wireless receiving system apparatus may have to be combined and diplexed with some domestic houses, and other premises, Access Network two-wire telephone circuits and because the telephone subscriber may also procure a BT plc Broadband Internet connection to their 21 CN ® exchange, BT plc has a policy of replacing wire pairs with four wires – i.e. 2 two-wire pairs – contained in a cable from the distribution point (DP) – usually located on a wood pole in the street...

...A Broadband® connection can then be accommodated in addition to the Government Communications system; the Broadband® connection is placed on the additional two-wire circuit. This is because there’s not enough bandwidth on one two-wire circuit for telephone apparatus to be combined and diplexed to a subscriber line with GCHQ receiving equipment together with the addition of a BT plc Broadband® Internet connection as well– see slides 40 to 54...

...The diagram, fig.1, above shows the four wires present in a typical cable acting as a 21CN Access Network subscriber line. Note that there’s a colour code: blue, orange, green and brown. Blue and orange constitute one wire pair whilst green and brown constitute the second wire pair in the cable...

fig.1

...Coaxial-cable systems involving multiplexing have now been largely discontinued for telephony purposes. They have a number of disadvantages over optical-fibre systems namely a narrower bandwidth, shorter regenerator spacing-distance and more weight...

...Optical-Fibre links use glass fibre surrounded by cladding to convey infrared light modulated with digital pulses usually involving a TDM or wavelength division multiplexed (WDM) system.At BT plc optical-fibres are usually found in the

Core Network and Metropolitan Network and interconnect the different levels of i-node –formerly “switching-centres”, pre-21CN...

fig.2Basic structure of an

optical fibre

fig.3Typical infrared light wave propagation in a single mode optical fibre*

* In the BT plc telecommunications infrastructure forms of multimode optical-fibre are usually used.

...Short-range SHF microwave-wireless links are sometimes found in the Access Network and Metropolitan Network. The Core Network, however, has a chain of long range microwave-wireless link towers spanning the UK at intervals of about 30 miles on average, constituting a number of hops (with “drops”) the most famous being the BT Tower in central London – beneath the ground is situated the BT Network Management Centre. It’s situated underground in order to survive a certain mega-tonnage of nuclear explosion; the BT Tower above it constitutes a communications hub. Underground, at this location, there’s also a fixed-line hub comprising optical-fibre, coaxial-cable and wire-pair multiplexed and private-circuit systems...

...This diagram, fig.4, shows the basic idea of an SHF microwave link. The transmitters (Tx) are usually implemented using solid-state electronic components that generate specific microwave-carrier frequencies digitally modulated with TDM signals. The data could represent digitised audio, video, military RADAR signals – also a form of video – or financial information etc. BT plc’s 21CN®chain of Core Network microwave-communications link towers use SHF frequencies between about 15 GHz and 40GHz – 10GHz into the Extremely High Frequency band, EHF...

fig.4

...BT plc’s Core Network microwave-communications link tower in London (photo no.2) . The London BT Tower was originally known as the “Post Office Tower” because the predecessor of BT plc was Post Office Telecommunications – a government department until 1969. It, and its equivalent in Birmingham, were part of the former trunk network from the mid 1960’s onwards and originally used a form of analogue modulation, with FDM, for each SHF carrier-wave radiated from horn aerials installed on aerial galleries...

Photo No.2 Photo No.3

BT Tower

London

BT Tower

Birmingham

... Horn aerials (Photo No.4) were technically difficult to install and sharp bends in waveguides had to be avoided in order to avoid large power losses in the signals reaching the horn transmission aerial. However, with advances in aerial design techniques, it was then possible to use highly efficient parabolic aerials,these having a greater bandwidth availability than horns. Additionally an optimal VSWR value was easier to obtain...Photo No.4

...As the network capacity grew, more parabolic dish aerials working on many different microwave-wireless frequencies appeared. Microwave links are limited in length by the curvature of the earth’s surface as the aerials must be in line-of-sight. The microwave-wireless horizon is ₄ ⁄₃ that of the optical horizon i.e. one third further in distance; the 4th third is, however, unreliable...

...Microwave-wireless signals are affected by weather conditions and reflections from water, if they cross the sea or other large expanse of water, causing fading. To overcome fading two dishes can be used and spaced a distance – several multiples of the wavelength of the carrier frequency apart – so they were affected differently. At the receiver the strongest signal could be selected at any instance of time. These days, however, BT plc usually use “polarization-diversity” reception (see Part 8 of 11, slide 24) instead of a “spatial-diversity” arrangement as only one receiving parabolic aerial is required; it has two elements at the parabolic dish aerial’s focus. One is usually horizontally polarized whilst the other element is vertically polarized...

...A spatial-diversity parabolic dish aerial arrangement, in terms of its various sub-systems, is shown schematically below, in fig.5:

fig. 5

... As can be seen from figure 6, there is usually one or more reflected rays arriving at the receiving site concerning a specific hop in a `microwave link tower chain. These reflected rays can add to the field-strength of the received ray – known as “phase addition”– or subtract from the field-strength of the received ray – known as “phase cancellation”...

fig.6

...The effect of partial cancellation on a digitally modulated free-space `link is to increase the Bit Error Rate (BER) of the signal at issue and so causing data corruption of the received signal – if the error correction system can’t cope. In the case of total phase cancellation of the carrier – which is rare –then reception of the multiplexed channels are lost completely...

...When using polarization-diversity* the receiving system that allows one parabolic aerial to be utilised for both receiving and transmitting simultaneously is considerably more simpler than is the case when using spatial-diversity. cf. fig.6...

* vertically polarized element and also a horizontally polarised one at the parabolic’s focus

fig.7

...Photo No.5 shows the Heaton Park, Manchester, UK, BT plc communications tower that’s involved with the 21CN’s Core Network transmission of the various signals communicated through the 21CN commented on earlier.

There’s a “drop” from this communications tower – in the form of cables – to the large Core Network i-node at Dial House in Manchester city centre carrying the various types of digitised signal outlined in slide 16, fig.4,...

Photo No.5

...Photo No.6 shows BT plc’s equivalent installation in Carlisle, Cumbria, UK. A Core Network i-nodeand also a broadcast networkdistribution and contribution circuitNSC is located at the `link tower’s base.

Of historical interest is the fact that thebuilding at the base of the tower, housing i-node-routing-apparatus, once housed a Tertiary* PSTN switching centre withassociated data storage systems – the “Volumetrics”; a state-of-the-art system is present there now...

Photo No.6

*This is in the context of ITU-T nomenclature concerning the former trunk network i.e.pre-21CN

...The communications traffic over this Core Network microwave link infrastructure can be of a “protection-circuit” nature i.e. in the event of fault occurrence along a number of fixed-line routes. However, it’s usually used for the distribution of RADAR signals from unmanned RADAR stations to manned monitoring centres where military personnel may monitor these signals on VDUs, and various GCHQ SIGINT systems e.g. COMINT, ELINT, and TELINT, indirectly, from various domestic, public, commercial, industrial, governmental and other military sites. Despite the narrower bandwidth available using microwave-wireless, when compared to an optical-fibre route, a chain of communications towers, each spaced a few tens of kilometres apart on average, is more easily defended from a military perspective, in comparison to a fixed-line route where there are ground-level “manhole” access-points for the purpose of allowing engineering and technical staff to gain access to pulse-regenerator systems, e.g. in the event of system-failure or system-replacement, and spaced every few kilometres along a given route...

fig.8

...Figure 8 shows the different forms of fixed-lines used at BT plc. The various gauges of wire and twisted-pair cable offer the narrowest bandwidth available of the four communications bearers considered here.

Coaxial cable systems offered a considerably wider bandwidth for the transmission of multichannel telephony and other multiplexed communications systems compared with twisted pair or other wire pair systems. They’re no longer widely used in what is now the BT plc Metropolitan Network and Core Network infrastructures.

Because the frequencies of the infrared-light band (many THz) are much higher than the UHF frequencies that can propagate down a coaxial cable it means that with optical-fibre systems the bandwidth available for digital data transmission is vastly greater, and therefore much larger multiplexed multichannel transmission systems can be implemented, than one using coaxial cabling...

...The advantages of using a free space microwave link in comparison with a landline are:

1. Cost is considerably less per-unit-distance of the transmission path concerning installation costs.

2. Maintenance costs are lower.

3. There’s a much lower risk of sabotage...

Photo No.7

The disadvantages of microwave links over fixed links:

...1. The SHF band occupies much lower frequencies on the electromagnetic spectrum compared with the infrared frequencies used by optical-fibre systems. Consequently considerably lower bit/baud rates have to be used with microwave systems because of the narrower bandwidth available i.e. carrier frequency αavailable bandwidth. A high capacity core network optical-fibre can transmit many tens, hundreds or even over a thousand gigabits/s – i.e. about 1.6 terabits/s. Contrast this to the several hundred megabits/s that can, at a maximum, be transmitted over a specific Core Network microwave link...

2. ...SHF-microwaves – above 10GHz – are susceptible to fading caused by precipitation. This increases the BER and can put a heavy burden on the error correction systems used in the receiving system. Precipitation fading is thus another limiting factor concerning the maximum bit/baud rate that can be utilised on a `link. Some microwave systems do, however, have automatically variable bit rate facilities that depend on sensing attenuation due to precipitation, or any other cause, through automatic BER analysis...

...All access network subscriber wire-pair lines terminate on a SLIC housed at the nearest appropriate BT plc premises. The SLIC can be considered to be an electronic system comprising a number of sub-systems that are used to perform a variety of functions concerning different services, other than POTs*, that can be interfaced to a subscriber line. “Other services” will be discussed from slide 29 onwards...

*POTs is an abbreviation for “Plain Old Telephones”

... A typical SLIC will provide selected services to a number of subscriber lines terminated on it. This will usually be for eight or more access network subscriber lines.

Electronic circuitry on a SLIC will mostly comprise integrated circuits as opposed to discrete components, some of which will be ASICs.

There will be a number of Analogue-to-Digital Converters (ADCs) and Digital-to-Analogue Converters (DACs) on each SLIC. One of each of these converters will provide the function for digitising the analogue telephone channel (the ADC) signal transmitted from the subscriber’s premises and converting a telephone signal that’s in digital form arriving at the SLIC from elsewhere in the 21CN back into analogue form (DAC) for application to the subscriber’s line so that their telephone set can receive the telephone call...

...In the case of a subscriber purchasing the BT plc Broadband® service, which applies a digital signal directly to the Access Network wire-pair connecting the relevant BT plc premises to the subscriber’s premises a Field Technician (FT), known to the public as an “engineer”, will visit the appropriate BT plc premises, housing the relevant SLIC , and will change the relevant signal transmission settings on the SLIC in order to allow a Broadband® digital signal to be available on the subscriber’s wire-pair line. The settings on the SLIC can also be accessed via a PC loaded with relevant BT plc bespoke software...

...The FT, employed in the Access Network part of the 21CN, can make the necessary changes and adjustments requested by the customer concerning data-usage-quota i.e. what level of BT plc Broadband® Service the subscriber concerned requires. Other BT plc engineering and technical personnel, including TTOs, based in other locations around the given area or even around the country, including of course BT plc’s Network Management Centre (NMC) in London, can alter technical settings on the SLIC in question, remotely, and so could potentially disable a subscriber’s Broadband®

connection, POT and/or “other services” etc...

“Other Services”:

... A SLIC in the 21CN can also provide a specifically set value of DC voltage, obtained from a 21CN local telephone exchange’s “central battery”; this being float-charged from a 23oV rectified AC mains electricity supply and applied to an Access Network wire pair for the purpose of “phantom powering” apparatus used for the following services – this list is not exhaustive ...see next slide

…1. microwave-wireless receiving equipment for GCHQ ELINT i.e. for a typical building’s activated electronic eavesdropping system radiating very low power signals, usually of the order of tens of nano-watts (nW) at carrier frequencies of several GHz – below 6.2GHz, approximately, because of signal-attenuation due to brickwork, on SHF.2. receiving low power microwave vehicle-tracking and

monitoring signals from activated surveillance systems, using microphones, in civilian vehicles – including those for the police, fire & rescue, and ambulance services – and for receiving low power microwave-wireless signals emitted from cybernetics-related EEG wireless/brainwave-surveillance implantable devices in some human-beingsand some animals…

...Continued from previous slide (“The SLIC: Part 6)...

3. powering physically very small eavesdropping devices that may be installed in BT plc subscriber line sockets and BT plc cable junction boxes by people handled by UK investigative agencies...

...In addition to telephony services the BT plc infrastructure is also involved with the communications for the following systems:

1. GCHQ eavesdropping of public and private buildings.2. GCHQ vehicle-tracking and monitoring of civilian vehicles.3. GCHQ EEG wireless-implantable & brainwave-emulator

cybernetics systems for both humans and animals.4. Broadcast sound and vision-circuits interconnecting studios

with other studios and their transmitter sites both nationally and internationally via terrestrial microwave links, fixed land-lines and satellite systems...

...GCHQ have short-range microwave-wireless receiving equipment based in some domestic homes and other buildings targeting other sites that are connected, sometimes combined and diplexed with the occupants telephone apparatus, to an existing Access Network wire pair circuit or using a second two-wire circuit within the same cable from its associated wood pole DP – if BT plc has got around to replacing their two-wire-only cable...

...The signals from such equipment are distributed to the Core Network and Metropolitan Network Volumetrics for recording and storage.

They are also distributed to a number of locations for listening in the UK and abroad via international circuits utilising a distributed-computer-system; the final link for listening locations in the UK usually being provided bya BT plc Broadband® connection...

...In addition to a distributed-computer-system, for accessing distributed eavesdropped-buildings signals, there is also a “hard-wired” listening receiver available which plugs into a standard BT plc fixed line socket connected to the Access Network...

...This hard-wired “listening box” contains demodulators, an audio amplifier, volume control and a number of switches to isolate the audio signal from eavesdropping in different rooms of the targeted building, known as “room-selection”, and ear surveillance, if available, together with dynamics...

...GCHQ have microwave-wireless equipment based in some domestic homes, and other buildings, which are combined and diplexed to Access Network wire pair circuits, often with the occupants telephone, for the reception of telemetry – supplying vehicles instrument-panel readings, and audio signals, obtained from microphones, from virtually all civilian vehicles. Actual tracking information is derived from the receiving node location and a signal field-strength reading provided by it. A GUI, usually utilising some form of Windows® operating system, displays this tracking data, overlaid over Ordnance Survey Map images; the scaling being user-selectable…

...These signals are recorded on the Core and Metropolitan Network Volumetrics and are distributed to a variety of listening locations in the UK and abroad using a distributed-computer-system. An intelligencer can connect to this system using a Broadband® connection or just listen to a tracked vehicle’s audio using a hard wired receiving device plugged into a BT plc socket...

...GCHQ have microwave-wireless receiving equipment in a range of buildings, though usually connected to a leased-line, via multiplexing apparatus, at a converted purchased domestic address. At a smaller channel capacity receiving site, a microwave-wireless receiver can use one of the two pairs of wires within an Access Network line cable to a functioning domestic address, or, if no domestic Internet Broadband® system is being used by the house’s occupant(s), it can be diplexed with the occupant(s) telephone apparatus two-wire circuit –without using the spare circuit – and connected for the purpose of receiving EEG and other brain signals emitted from an implanted device located in some human-beings and animals...

... In addition to the EEG, a form of full high-definition colour television signal, known as “eye surveillance”, can be processed from humans with an electronic EEG Wireless/brainwave internal surveillance brain implant together with an audio signal, known as “ear surveillance”, and processed from the subject’s sense of hearing in addition to an ECG and EMG trace – providing muscle-activation data of the subject’s limb movement concerned, in addition to the tactile sense. Only monochrome eye surveillance can be obtained from animals such as cats, dogs, bitches, agricultural and zoological animals...

...Traces as shown in fig.9, representing brainwave rhythms, can be extracted from received microwave-wireless signals emitted from a typical wireless EEG Implant (usually above 3 GHz in frequency) using demodulation...

fig. 9

...GCHQ have a large number of transmission sites around the UK, based at broadcasting masts & towers and co-sited with broadcasters Tx aerials. These sites are linked, via leased-lines using the 21 CN® infrastructure, to centres around the country that originate brainwave emulations e.g. auditory, visual, ECG and muscle-activation (EMG) etc...cont.

...The signals in question are modulated onto a microwave (line of sight transmission) suppressed carrier wave for reception by wireless cybernetics electronic IC implants (Brainwave Emulators) in some human-beings and animals brains.

Photo.8 shows Arquiva’s Winter Hill mast that acts as anaerial support structure.

Its primary purpose is to radiate Digital Terrestrial Television,(DTT), Digital Audio Broadcasting (DAB) and analogueVHF-FM radio services for various broadcasters, the main ones being ITV, BBC, ILR and INR. The mast also has aerials installed on it for the purpose of radiating suppressed microwave carriersignals (above 3.2 GHz but below 6.2GHz) that can be modulated with synthetic auditory, visual, ECG, EEG, EOG and EMG signals that are known as “emulations” for cybernetics systems...

Photo. 8

...The BT plc infrastructure that involves the 21CN, interconnects the Brainwave Emulator Implant transmission sourcing facilities at Winter Hill – whose SHF wireless cybernetics Tx facilities are capable of reaching targets located in most of North West England – to specialist centres for originating synthetic brainwaves in different locations around the UK, incl. abroad, using “leased-telecommunication-lines” also known as “private-circuits”. This involves the 21CN...

…A speech, brainwave (involving implantable IC devices) and image recognition system is thought to be in operation which involves the use of a supercomputer( previous ones containing several thousand CPUs in an three-dimensional array), based beneath the groundwithin the NMC complex in central London, and smaller computers based at some of the Metropolitan Network i-nodes and all of the Core Network i-nodes. The i-node-based computers upload programmed-in words, phrases, abbreviations and names that have been recognised, on nearly of all the communications systems that the 21CN is involved with, every few minutes, in a sequence…

…to this aforementioned 21CN national supercomputer. Intelligencers, which have access to this `recognition system, do so via their own desktop PC, netbook, i-phone or tablet ICT device etc. by logging-on to one of a number of GCHQ servers linked, usually via a Internet Broadband provider and using an encryption system, to this supercomputer installation. SMS alerts can also be generated by this `recognition system and sent to relevant intelligencers mobile-phones and/or email boxes etc. when something key is recognised by this 21CN speech, brainwave and image recognition supercomputer system...

...BT plc has a Network Management Centre (NMC) located in a base beneath the ground, above which the BT Tower in central London — the “NMC” in Oswestry, Shropshire, is clearly a decoy. It can divert Core Network and Metropolitan Network traffic to other core and metropolitan communications routes in the event of congestion or fault occurrence (thereby overriding AAR).

The supercomputer that’s part of the 21CN’s speech, brainwave and image recognition system is based within the NMC complex located beneath the ground in central London (see the previous two slides)…

... The NMC also has powers to shutdown local exchanges, Metropolitan and Core Network i-nodes and even individual subscriber-lines or just some of BT plc’s telephone service features, e.g. The NMC could disable the “BT Answer” facility that serves a specific subscriber’s line.

Quite a lot of network-management functions are delegated to local exchange staff for day-to-day operations in the Access Network...

...BT plc’s NMC also has Telecommunication Management Network (TMN) links with all other public telecommunication operators e.g. Vodaphone, 3 Network, Orange and O₂, etc. that allows it to override the smaller NMCs based at these `operators e.g. in order to shut one particular `operator’s network down and also to record and store the throughput of these operators networks on BT plc’s Volumetrics. There are also links of a similar description to the British Broadcasting Corporation’s own NMC which can monitor and/or control the CTAs* and central apparatus areas based in its regional broadcasting centres and local radio stations respectively —or, if integrated, both. This arrangement with BT plc is a governmental requirement...

* CTA is an abbreviation for “Central Technical Area”

...Functions such as Access Network line testing, line ceasing, accessing billing information etc., can be implemented by Field Technicians and Telecommunications Technical Officers* (TTOs & HTTOs**) from a PC operating specialist Windows software...

* TTOs are each of a designated numbered level** HTTOs are “Higher Telecommunications Technical Officers”

...TTOs are based at Access Network, Metropolitan Network and Core Network premises. The NMC reserves the right to withdraw delegated network-management functions from Access, Metropolitan & Core Network personnel...

... The NMC is also fully involved with signals received from eavesdropped buildings obtained from GCHQ receiving apparatus. Activation of individual eavesdropping devices embedded within the walls of buildings can be activated from the NMC via a touch screen, keyboard or other peripheral, where GCHQ wireless receiving equipment (co-located with an eavesdropping device wireless-activation transmitter) is usually setup in the targeted building’s locality...

...Activation functions can also be delegated to other intelligence services personnel issued with a Windows PC and appropriate bespoke software with an appropriate connection to a server based system. It’s thought to be the case that practically all domestic homes etc. SHF microwave-wireless embedded wall eavesdropping systems are activated and recorded; on the relevant SHF spectrum allocations there’s enough wireless bandwidth for this to be the case…

…In municipal high-rise flat complexes wired eavesdropping systems are used which are connected to multiplexing units, where their signals are digitised, and applied as a TDM signal to a metallic path leased line – virtually all lines have an IP address – and are communicated to the Volumetrics for recording and storage. This continuously digitised audio data is kept for at least five years, if no data-deletion order is issued to relevant NMC staff. This is also the case with the eavesdropping systems installed in private homes...

...Vehicle tracking & monitoring devices can be activated from the NMC. Activation and listening rights can also be delegated to appropriate GCHQ personnel, away from the NMC, and to other intelligence services and law enforcement agency staff with an appropriate PC operating a

Windows® operating system and bespoke

software...

... They can also access recordings of tracked signals via their PCs (and the audio from the tracked vehicle concerned, that’s been obtained from some form of electretmicrophones) which have been stored on the Volumetrics (data-storage repositories), with an appropriate connection to relevant GCHQ servers linked to them usually using a BT plc Broadband® connection together with theinvolvement of an encryption system...

...The NMC is involved with the monitoring and routing of the signals from the EEG Wireless Implants already mentioned. It’s possible to actually access these `implantable devices signals at the NMC, for test purposes, using headphones and flat screen systems linked to a specialist computer system – part of the overall network management system for 21 CN®...

...Monitoring of brainwave implantable device signals can also be delegated to appropriate personnel, nearly anywhere, with a PC or smaller computing device e.g. a “Netbook”, “Tablet” or “Smartphone”, running a Windows®

operating system – or compatible OS – and bespoke software, usually with an appropriate BT plc Broadband® connection to GCHQ server systems linked to the Volumetrics at BT plc; this usually being the case for all systems...

...With all the GCHQ systems discussed here, it’s possible to introduce a time delay from the NMC, or control can be delegated to personnel elsewhere, for listeners and viewers to a signal for “security reasons” usually ranging from a few seconds to several minutes. This enables senior personnel to block signals arriving to lower level personnel briefly or indefinitely...

...The NMC can also become involved with sound and vision circuits to and from broadcasters. Individual circuits can be shutdown that interconnect a studio centre with its transmitter(s) and other broadcasters. The three main groups of sound and vision circuits are known as:

“Network Distribution”, “Network Contribution” “Talk-back” ...

...The NMC even has powers to shutdown entire broadcast leased-line Network Switching Centres (NSC) based in the major cities. This could happen in the event of a national emergency or civil disturbance.The largest NSC in the UK is located in central London and is at the base of the BT plc Tower there...

...Talk-back circuits are for narrow-band communication between staff in different studio locations and these circuits are active when technical staff e.g. audio and/or vision supervisors are arranging and/or supervising a live programme contribution from a distant studio or an outside-broadcast (OB) location.`Distribution and `contribution circuits can be disconnected and programmes “blacked out” by the BT plc NMC in London...

...BT plc is involved in operating a distributed-computer -system that makes available intercepted telephony and general internet traffic, both Broadband and “narrow-band” Dialup and GCHQ surveillance systems, i.e. COMINT, incl. ELINT, to intelligence agencies, other than GCHQ itself, and also to law enforcement agencies e.g. the area constabularies, including investigative agencies abroad, who can transfer recorded telephony etc. to a removable secondary storage data format e.g. CD-R, USB Flash Drive or ZIP drive etc., for the purposes of intelligence gathering or criminal evidence admission to a court-of-law, where a necessary IoCwarrant is in force or, where a branch of the High Court of Justice has made these recordings admissible, after listening and/or viewing them…

…The entire 21 CN® throughput is recorded and kept for several years. The exact time-frame of data-storage-retention is dependent on the nature of the digitised signal concerned e.g. digitised narrow-band audio is held for many years longer than digitised high-definition video. The data from all the audio & visual systems using the 21 CN® is stored on high-density solid-state and holographic (non-volatile) data-storage systems known as the “Volumetrics”...

...The Volumetrics are located in the Core and and some of the Metropolitan Network I-nodes and total several geopbytes within the 21CN®.They record and store telephony traffic signals

and a variety of other telecommunications and communications signals from other networks in digitised form that initially used some or all parts of the BT plc communications infrastructure. These separate networks, apart from other PTOs, have now been fully merged into the 21CN...

– they’ve now installed more modern Volumetrics with greater data storage capacity i.e. a few tens-of-brontabytes are installed in the Carlisle i-node premises alone, for instance (featured earlier).The Volumetrics that aren’t holographic data storage systems constitute solid-state electronic volatile memory and therefore require an Uninterruptable Power Supply (UPS) if stored data isn’t to be lost in the event of an electricity mains power failure...

1. The 21CN integrates a number of separate networks that originally used some or all of the previous BT plc telecommunications and communications infrastructure – including the Internet in the UK – so they’re under one umbrella.

2. The 21CN uses Internet Protocol (IP) to identify communications devices in addition to POTs and PCs, such as Access Network and leased-lines, that are connected to SLICs etc. This offers a number of advantages to public subscribers, business, industry, military and governmental users.

3 . Because IP addressing is used, there’s more reliable routing oftelecommunications, and communications signals in general, so enabling network-management to be implemented more easily, especially using IPv6.

1. “Transmission Principles For Technicians”Author: DC Green, M Tech , C Eng, MIEE, pub. 1988 by the Longman Group UK Ltd.© Longman Group UK Ltd 1988.

2. “ Newnes Telecommunications Pocket Book – Third Edition”Author: Steve Winder pub. 2001 by Newnes – An imprint of Butterworth-Heinemann © Reed Educational and Professional Publishing Ltd, 1992, 1998, 2001:

3. “Fundamentals of Telecommunications – 2nd Edition”Author: Roger L. Freeman pub. 2005 by the IEEE© 2005 by Roger L. Freeman. All rights reserved:

4. Personal experience – two week “Work Experience” Placement in Merseyside with British Telecommunications plc in April 1995 and arranged by John Reid, BT plc Education Liaison Officer, Walker Street building, 170-175 Moor Lane, PRESTON, Lancs., PR1 1BA, UK:

5. Image on Title Slide; courtesy of FreeFoto.com: One of BT plc’s core network microwave communications link towers located at Telephone House (a Core Network i-node), Lionel Street, Birmingham, UK:

6. “Newnes Audio and Hi-Fi Engineer’s Pocket Book – Second Edition “, Author Vivian Capel pub. 1991 by Newnes – an imprint of Butterworth-Heinemann Ltd © Vivian Capel 1988, 1991:

7. “Newnes Data Communications Pocket Book – Fourth Edition” , Authors Steve Winder & Mike Tooley, pub. 2002 by Newnes – An imprint of Elsevier Science. © Steve Winder & Mike Tooley, 1989, 1992, 1997, 2002:

8. “Newnes Radio and RF Engineering Pocket Book – Third Edition”, Authors Steve Winder & Joe Carr, pub. 2002 by Newnes – An imprint of Elsevier Science.© Steve Winder 1994, 2000 and 2002:

9. “Newnes TV & Video Engineer’s Pocket Book – Third Edition” author Eugene Trundle, pub. 1999 by Newnes – An imprint of Butterworth-Heinemann. © Eugene Trundle 1999.

10. “Understanding Telephone Electronics – Fourth Edition” , authors Stephen J. Bigelow, Joseph J. Carr and Steve Winder pub.2001 by Newnes – an imprint of Butterworth-Heinemann.

© 2001 by Butterworth-Heinemann.

11. Personal experience: Four weeks Unpaid Training Attachment in the Central Technical Area (CTA) of BBC Midlands Pebble Mill premises; Its former regional broadcasting centre located in Birmingham, UK, April 1994.

12. Personal experience: informal visit to BBC Radio Merseyside’s “18th

Birthday Open Day” in Liverpool, UK, in November 1985:

13. Personal experience: informal visit to BBC Radio Merseyside’s “20th

Birthday Open Day” in Liverpool, UK, in November 1987:

14. Personal experience: One day long BBC GMR* “Presenters Course” conducted at BBC Northwest, New Broadcasting House, Manchester, UK in December 1990:

*BBC GMR has since been renamed BBC Radio Manchester

15. Personal experience: Informal visit to BBC Radio Cumbria’s “one-camera” remote TV studio – camera position controlled remotely from New Broadcasting House, Mancs. via a leased-telecommunications link – at their former Hilltop Heights premises, Carlisle, UK, in August 1988.

16. TCIL 17 Microwave Link Design

17. Andrew Communications: a Commscope company. Information obtained from their website concerning dual-polarisation shrouded parabolic dishes for “long haul” SHF microwave link hops i.e. Core Network `links. a Commscope company:

18. Salford College of Technology – which became University College Salford before being absorbed by the University of Salford. This college organised a technical student visit to BBC Northwest, New Broadcasting House, Manchester, UK, during October 1991. Here, I was shown around the television studio facilities and its CTA where I queried various systems:

19. Royal Television Society (RTS) visit to `New Broadcasting House, Mancs., UK to see the then new CTA facilities in November 1994:

20. The public Internet website of Government Communications Head Quarters (GCHQ):

22. International Telecommunications Union (ITU)

Information on RF and microwave transmission standards and also on IP networking standards – IP version 6 (IPv6) being of state-of-the-art communications relevance –and, additionally, on PSTN switching centre nomenclature formerly used by BT plc, pre-21CN, and which is still in use in some other countries whose subscribers call UK telephony and Broadband® lines, see the ITU’s Internet website. Additional information on IPv6 is available by clicking on the IPv6 insignia, displayed below:

[ Note: website links are not active for “.wmv” file viewers]

About The Author

Joseph P. Campbell is 39 years old and is qualified with an HNC in marine navigational systems engineering from Liverpool Community College that he gained in 1997. This branch of engineering involves the use of telecommunications and communications systems in general.

He’s a qualified Radio Amateur, call-sign G7OKR, and has a general interestin electronics & communications engineering in addition to related technologies and sciences. Email: g7okr@hotmail.co.uk

Joseph P. Campbell, HNC Nav. Eng.

Joseph P. Campbell

End of This 21st Century Network®Presentation (revised)

ByJoseph P. Campbell,

HNC Marine Nav. Sys. Eng.

© 2010 Joseph P. Campbell

(Revised 1st May 2011)