Stebbing Hall, Lubberhedges Lane, Stebbing, Essex CM6 3BU (Registered Office)
Telephone 01371 856964 Mobile Phone: 07860 297453 Fax: 01371 856984
Email: info@emc-consultants.co.uk Web: http://www.emc-consultants.co.uk
12th September 2012
REF: ING1/0912
TELECOMMUNICATIONS ENVIRONMENTAL
IMPACT ASSESSMENT OF RADIO & TELEVISION
INTERFERENCE - KINGS TRIANGLE
DEVELOPMENT, MAIDENHEAD.
CLIENT: ING Real Estate Development UK LTD.
Stephen Austin, B.Sc., C.Eng., F.I.E.E., F.C.I.B.S.E. (Director)
VAT No. 538 3308 42 Reg. No. 2382512 Cardiff
CONTENTS
1.0
2.0
2.1
2.2
2.3
3.0
3.1
3.2
3.3
3.4
4.0
5.0
5.1
6.0
7.0
PAGE No.
INTRODUCTION.
TECHNICAL BACKGROUND.
Signal Transmission.
Electromagnetic Shadows.
Reflections.
ASSESSMENT OF EFFECTS.
Radio Reception.
Site Observations and Baseline Conditions.
Electromagnetic Shadows.
Reflections.
AFFECT OF DEVELOPMENT CONSTRUCTION UPON
TELEVISION RECEPTION.
MITIGATION MEASURES.
Alternative Television Transmitter Locations.
CELLULAR COMMUNICATIONS.
CONCLUSION.
Appendices: 1.
2.
3.
Locations and Technical Information for
Television Transmitters Serving Maidenhead.
Worst Case Likely Shadows Caused To Each
Television Transmitter.
Television Shadow Zones Superimposed
Onto Local Area Map.
1.
1.
1.
2.
3.
4.
4.
4.
6.
8.
8.
9.
10.
10
11.
1.0
INTRODUCTION
The assessment is based on a desk top study that considers the impact of a number of multistorey structures upon ambient levels of airborne communications electromagnetic fields.
The study analyses materials and geometry of the buildings with respect to incident
electromagnetic fields, and by the use of ray tracing predicts effects. Where communication
transmission quality may potentially be impaired, available mitigation options are indicated.
The analogue to digital television transition occurred in April 2012 causing some aspects of
multi-path television interference effects due to reflection to be diminished (because digital
TV is more resilient). However, any signal reduction interference effects due the presence of
the development will remain unchanged. A site visit was undertaken in order to ascertain
basic baseline conditions. The study was carried out by EMC Consultants Ltd.
2.0
TECHNICAL BACKGROUND
2.1
Signal Transmission
Airborne communications transmissions considered within the study are broadcast radio,
satellite television, terrestrial television and cellular telephone. All use electromagnetic field
propagation to link electrical energy from transmit aerial to receive aerial, which is then
converted into sound and vision. Radio and terrestrial television utilise energy within the
radio frequency band, cellular telephone and satellite television utilise microwave energy.
Broadcast radio within the UK occupies the lower part of radio frequency spectrum extending
from a few hundred kHz for long wave transmissions, to a few MHz for medium wave, up to
around 100 MHz for FM transmissions and between 217-230 MHz for digital radio. Stated
frequency ranges cover the LF (low frequency) band, through MF (medium frequency), HF
(high frequency) and up to the VHF (very high frequency) band. Terrestrial television within
the UK occupies an upper part of the radio frequency spectrum from 470-850 MHz and is
included within the UHF (ultra high frequency) band. Analogue television transmissions
were switched off during April 2012 in London. Part of the redundant TV spectrum will be
sold off as a result. Cellular telephone microwave transmissions also fall within the UHF
band. Satellite television microwave transmissions fall within the SHF (super high
frequency) band. Television signals are propagated from a network of transmitters located at
key points throughout the country to provide nation-wide coverage. The Maidenhead area
receives high power digital TV coverage from Crystal Palace (OS ref: TQ339712) which is
located approximately 47.5 km to the south east. Drawing ref: KT1 within appendix 1
indicates technical details for the transmitter and shows its relationship to the site in
Maidenhead. Additionally, a local television transmitter also serves the immediate area and
is positioned approximately 6.6 km to the north east of the Development. The Wooburn
transmitter is a relay of Crystal Palace, is located at OS co-ordinates SU916873 and provides
low power digital TV services. It has a power output of only 20 watts per channel compared
to 200 kW per channel transmitted by Crystal Palace. Crystal Palace provides a full version
-1-
Cont….
of ‘Freeview’ via the following 6 multiplexers:
BBC A (channel 23) – BBC1, BBC2, BBC3, BBC4, BBC News, BBC Parliament, 301, 302.
D3 + D4 (channel 26) – ITV1, Channel 4, Channel 5, ITV2, Channel 4+1,More4, E4,
ITV+1,Teletext.
BBC B (channel 30) – BBC1 HD, ITV1 HD, Channel 4 HD, BBC HD, 301 HD.
SDN (channel 25) – ITV3, ITV2+1, 5*, 5USA, Quest, The Zone, Channel 5+1, ESPN.
ARQA (channel 22) – Pick TV, Dave, Really, E4+1, challenge, Food Network, TV Stars,
Sky News, TV News.
ARQB (channel 28) – Yesterday, Film 4, 4 Music, Viva, ITV 4, 4seven, Al jazera, Sky
Sports 1, Sky Sports 2.
Wooburn provides a limited version of ‘Freeview’ (Public service broadcasts only) via the
following 3 multiplexers:
BBC A (channel 56) – BBC1, BBC2, BBC3, BBC4, BBC News, BBC Parliament, 301, 302.
D3 + D4 (channel 48) – ITV1, Channel 4, Channel 5, ITV2, Channel 4+1,More4, E4,
ITV+1,Teletext.
BBC B (channel 52) – BBC1 HD, ITV1 HD, Channel 4 HD, BBC HD, 301 HD.
The Development will comprise varying height predominantly reinforced concrete/steel
frame structures, clad with brick/stone with a large proportion of glazing to the retail, office
and residential components. Car park facades will be perforated and profiled metal mesh or
similar. Only those parts of the structures that will exceed the height of surrounding
buildings have the potential to cause adverse effects upon terrestrial television reception.
Satellite communications transmissions typically operate at around 10 GHz which is a
microwave transmission and falls into the SHF (super high frequency) band. Satellites are
predominantly located in a Southerly direction of the UK typically forming an angle of
elevation between 17-30 degrees above the horizon. The further north considered, the lower
the angle for reception. Satellites are in a geo-stationary orbit above the equator. The main
satellite of consideration with respect to local residents within the Maidenhead area is Astra
2, which provides Sky and is located in a south easterly direction from the site.
The impact of the Development upon described communications transmissions will be
different for each service. Radio, satellite television and terrestrial television all operate at
different frequencies, which cause different responses to the presence of an obstacle.
Transmission source locations and power outputs will also differ greatly. Principal concerns
relating to any large structures are signal blocking and reflection.
2.2
Electromagnetic Shadows
Electromagnetic fields are propagated in exactly the same manner as light, and as such can
also produce a shadow. An electromagnetic shadow is an unwanted area of reduced field
strength that can cause poor signal quality. Shadows can be caused by any conductive (or
-2Cont….
slightly conductive/capacitive) obstruction. Extent of shadow for any obstruction is
dependent upon transmission frequency, propagation angle with respect to the obstruction,
and the geometry and conductivity of the obstruction.
Lowest transmission frequencies have the greatest ability to bend around (diffract around)
obstacles. The higher the transmission frequency, the more directional the transmission will
be, and the greater the transmission losses when encountering a conductive medium. Trees
close to a house can severely reduce signal reception of satellite television operating in the
region of 10 GHz merely due to the presence of moisture within leaves (which are very
slightly conductive), but will have negligible affect upon terrestrial TV operating at 0.6 GHz.
A spherical metallic object in the path of a 10 GHz transmission will produce a greater
shadow than for a 0.6 GHz television transmission. Both will be subject to electromagnetic
energy reflection, but the lower frequency transmission will to a certain extent follow the
contours of the spherical obstruction more closely before re-radiating and hence reducing the
shadow area. This effect is known as diffraction and tends to reduce the shadow to the form
of a long cone tapering away from the sphere rather than causing an almost parallel sided
cylinder.
2.3
Reflections
Reflection occurs when an electromagnetic wave strikes a denser reflective medium than it is
travelling through (that medium would normally be air), as when light strikes a mirror.
Maximum reflection occurs from highly conductive surfaces such as a metallic objects, and
minimum from surfaces such as plain glass and plastic, where reflection will be minimal and
the wave will pass straight through; although its direction will be altered (termed refraction).
Where plain glass is positioned at an acute angle to an incident electromagnetic field,
reflection will occur in much the same manner as a pebble bounces across water. Some
mediums, such as glass, having a coating to prevent solar loss/gain and fall between the
previous examples; reflecting a significant part of any incident wave and permitting part to
penetrate through.
Due to the phenomenon of skin effect, waves reflected from any predominantly metallic
surfaces (such as structural steel, metallic facades or coated glazing such as low ’E’) will not
penetrate the surface by more than a few microns, and almost all electromagnetic energy will
be reflected. If conductive surfaces are concave, resultant reflections will tend to be
concentrated (i.e. cause a stronger signal). If conductive surfaces are convex, resultant
reflections will tend to be dispersed/scattered (i.e. cause a weaker signal). If conductive
surfaces are irregular, resultant reflections will tend to be scattered in all directions. In
practice, many building facades comprise a combination of all stated configurations.
Unlike analogue television, digital television does not tend to suffer as badly from reflections
(multi-path transmissions) causing delayed images, and has much greater immunity to this
type of interference. Even the weakest received primary signals (up to a certain point) are
-3-
Cont….
recognised and can then be fully reconstituted, but secondary delayed signals are rejected.
Multi-path reception does not adversely affect the received quality of DVB television
transmissions (DVB is digital video broadcasting). In fact, received reflected signals can
actually increase received signal strength/quality. Any reception problems are most likely
when received signal levels are very low (then a TV screen tends to pixelate and freeze up).
3.0
ASSESSMENT OF EFFECTS
3.1
Radio Reception
Broadcast radio operates within the lower parts of the radio frequency spectrum from 148
kHz for long wave up to around 108 MHz for FM, and between 217-230 MHz for digital
radio. At those frequencies propagation losses are low and transmissions have the ability to
bend around and over many types of obstacles, particularly hills, atmospheric layers etc. This
property is called diffraction and allows radio waves to "cling on" around the corners of
buildings and to a certain extent reduces their presence. Generally, AM and FM radio
transmissions will not be significantly affected by the presence of additional buildings. Radio
transmissions do not suffer delayed reflections, their is no direct equivalent to TV ghosting
(apart from phasing whereby a received signal seems alternately to get stronger then weaker).
Radio transmissions into the area are provided from more than one location, thereby
maximising reception possibilities. In this instance they are provided from Crystal Palace,
Alexandra Palace (OS ref: TQ296900), Reigate (OS ref: TQ256521) and from Brookmans
Farm (OS ref: TL259050). The presence of the Development will cause electromagnetic
shadows, and electromagnetic energy to be reflected from it, but they are the only affects the
Development is likely to cause. In the unlikely event that radio reception is impaired, either
local FM aerials could be installed, or digital audio band (DAB) radios and aerials could be
utilised. It is concluded that radio reception in the vicinity of the proposed Development is
unlikely to be significantly impaired.
3.2
Site Observations and Baseline Conditions
The Development will comprise varying height reinforced concrete/steel frame structures,
clad predominantly with glass along with some metal. Only those parts of structures that will
exceed the height of surrounding buildings have the potential to have an adverse effect upon
terrestrial television reception (beyond around 10-15 m above ground height facing
transmitters of interest). In this instance that mainly applies to the highest parts of buildings
NB1-NB5. Because of its position, and because it will be lower than the others, building
NB6 will not cause any shadowing effects from either of the considered transmitters. The
structures will cause both electromagnetic shadows and reflections. The actual extent of any
shadows is likely to be somewhat less than those calculated due to TV signals tending to flow
around/over the structures (termed diffraction). Reflection effects from the structures will
tend to be reduced due to some limited signal absorption along with re-reflection and some
signal scattering due to facade surface changes/irregularities, which will lessen any likely
adverse effects upon surrounding areas. The Development will cause electromagnetic
-4-
Cont….
shadows to the north west (due to the Crystal Palace transmitter) and electromagnetic
shadows to the south west (due to the Wooburn transmitter), refer to appendix 2 drawings ref:
KT2 & KT3 for details. North west facing elevations may also have some very limited affect
upon the extent of shadow caused to satellite television.
Summarising:
*
Any TV signal electromagnetic shadows resulting from the presence of the
Development will extend in a north westerly direction from the site for the Crystal
Palace transmitter, and to a south easterly direction from the site for the Wooburn
transmitter. All Shadow lengths and widths will be significantly diminished due to
diffraction effects. There will be the possibility of some limited poor terrestrial
television reception within those areas and possibly some very localised poor satellite
reception very close to north westerly elevations of the Development.
*
There will be the potential for reflections in various directions from the Development.
Any adverse effects upon television reception are anticipated to be minimal as
analogue television signals have been switched off and digital TV is more resilient to
reflections.
Baseline Conditions
There is a high density of residences Along the Crystal Palace shadow to the north west of the
Development (refer to appendix 3 local map ref: KT4). Inspection along a sample of the
roads within around 2 km confirmed that all aerials without exception were directed towards
the Crystal Palace transmitter. Aerial types varied from standard to high gain types. Most
seem to be fitted at or about the highest locations on most of the dwellings. Dwelling types
are predominantly 2 & 3 storey, although a few are multi-story residences. No communal
aerials could be seen on multi-story residences. Around 25-35% of residences seen have
satellite dishes. Cable television distribution cabinets and connection points could be seen
within many of the pavements. It was also noticeable that the Crystal Palace shadow passes
along roads that are elevated above the height of the future Development. By implication,
any shadow will be reduced in length as a result. Along the Wooburn shadow to the south
west the Development (refer to appendix 4 local map ref: KT4), all aerials observed were
oriented towards the Crystal Palace transmitter. Within around 1 km of the Development, the
area has very few residences. From the local area map it can be seen that most of the shadow
zone falls across a School and a Golf Club. Relatively few households will be tuned to the
Wooburn transmitter anyway. Ofcom estimates that only 3000 residents in total are tuned to
Wooburn, compared to 4.5 million tuned to Crystal Palace.
The only way to know for sure how good the existing quality of terrestrial TV reception is
within and along the predicted shadow zones, is to carry out a television baseline survey
before demolition and construction of the Development commences.
-5-
Cont….
According to the Ofcom site finder there are five cellular telephone base stations in the
immediate locality of the Development. Only two could be seen during the site visit.
The impact of the Development upon them and vice versa is likely to be minimal (refer to
section 6.0 of the report for base station assessment).
3.3
Electromagnetic Shadows
Satellite Television
Satellites in geo-stationary orbit in the southern hemisphere are so high that they form a very
acute angle to any structure at ground level. An angle of approximately 26 degrees (the
approximate angle for reception in this part of the UK) causes a shadow of only 33 m deep to
the north of the highest future structural point of Block NB1 (at 43.6 m AOD). Actual
shadow width and direction depends upon the satellite being considered. For the Astra 2
satellite the shadow will be towards the north west of the Development. Such a small shadow
area is unlikely to cause many difficulties (particularly as it falls partly across a commercial
and not a residential area. In the unlikely event that any residential areas close to the
Development have no satellite reception, it may be possible just to relocate a dish or, if that
does not reinstate the signal, possibly obtain a cable connection (although cable is not
confirmed to be available in the immediate vicinity of the Development, but is further away).
It is therefore confirmed that the Development will have insignificant impact upon satellite
television reception.
Terrestrial Television
For any given electromagnetic source, the extent of an electromagnetic shadow (i.e. potential
area that may suffer TV signal reduction) is determined by the size, orientation and
construction materials present within the obstacle considered. Proposed building structures
will predominantly be of steel frame and concrete construction, clad with brick/stone and a
large proportion of glazing to retail, office and residential accommodation. Car park facades
will be perforated and profiled metal mesh or similar. All described materials will be present
along elevations that face Crystal Palace and Wooburn TV transmitters. The worst part of
any potential shadow on the more critical north west sides of any buildings could be expected
to see a signal reduction of between 75-90% (i.e. signal loss of 12-20 dB).
The main Crystal Palace TV transmitter is located to the south east of the site 47.5 km away
in a direction south 78 degrees east (refer to drawing KT1). The highest part of any proposed
structure (Block NB3 at 57.7 m AOD) forms an angle of incidence with the Crystal Palace
transmitter of 0.33 degrees below the horizontal. There will be one overall shadow for each
transmitter that will comprise a number of individual elements of varying width/length
determined by structural step changes in height and geometry of the buildings with respect to
each television transmitter. With reference to drawings KT2 & KT3 within appendix 2, the
following electromagnetic shadows will result due to the presence of the Development:
-6-
Cont….
Crystal Palace
Drawing KT2: an electromagnetic shadow will be propagated in a
direction north 78 degrees west. The overall shadow will be a maximum
of 4.5 km long and 192 m wide. Individual elements will vary both in
width and length. A minor part of the shadow will be a maximum of
around 2.7 km long/36 m wide and will be due to blocks NB1/NB5. The
bulk of the shadow will be due to blocks NB3/NB4 and will be a
maximum of around 4.5 km long and 156 m wide.
Wooburn
This transmitter is very low powered at 20 Watts per multiplexer and
only serves a limited number of local residents. No aerials could be seen
tuned to Wooburn during the site visit. Wooburn is a relay of Crystal
Palace and delivers a restricted Public service broadcast version of
‘Freeview’ via three multiplexers (refer to section 2.1 for details).
Drawing KT3: an electromagnetic shadow will be propagated in a
direction south 24 degrees west. The overall shadow will be a maximum
of 1.9 km long and 157 m wide. Individual elements will vary both in
width and length. Approximately half of shadow will be a maximum of
around 1.1 km long/80 m wide and will be due to blocks NB1/NB2. The
remaining part of the shadow will be due to blocks NB3/NB4 at a
maximum of around 1.9 km long and 77 m wide.
Summarising for both Transmitters - In practice, the width of any resulting shadow zones will
be reduced by TV signal surface skin currents following the building facade profiles around
their edges before re-radiating (termed diffraction). Effectiveness of shadow width reduction
will be determined by the homogeneity of conductive metalwork and glazing at the corners of
the building (i.e. good continuity of metalwork around corners will enable skin currents to
flow along/around). Shadow length reduction follows the same principle at roof top level. If
uppermost roof edges are electrically continuous without any sudden ridges (which tend to
cause signal scattering), TV signal surface skin currents will be able to flow around roof
edges and hence help to reduce shadow lengths. Additionally, as mentioned under baseline
conditions: It was also noticeable that the Crystal Palace shadow passes along roads that are
elevated above the height of the future Development. By implication, any shadow will be
reduced in length as a result.
If there were any problems related to poor signal strength along any parts of the predicted
shadow zones, it may be necessary to boost the signal strength. If a received signal is only
poor (i.e. not eliminated entirely), then it should be possible just to install a local amplifier
and if necessary change an existing standard aerial for a high gain/extra high gain aerial; or,
alternatively, relocate or increase the height of a receive aerial. However, if signals are lost
altogether, then some aerials may have to be realigned to another transmitter. There are other
transmitters in the locality that are unlikely to be affected by the Development. A list of
possible (albeit limited) alternatives are provided within section 5.1.
-7-
Cont….
3.4
Reflections
Building facades will be primarily brick and stone with a large proportion of glazing to the
retail, office and residential components, with the car park facades in a perforated and
profiled, metal mesh or similar. Building perimeter glass is assumed to be double glazed.
Such construction will cause significant television signal reflections. It is anticipated that up
to 60-65% of incident TV signals will be reflected from the combination of windows, steel
structure and concrete surfaces along elevations that face television transmitters. Television
signals reflecting off an obstacle travel further and arrive later than a directly received
transmission (termed multi-path reception). The potential effects of such reflected energy is
dependent upon the type of television transmission being received. Fortunately all analogue
TV signals (which are the most susceptible to signal reflections) have been switched off.
Generally, multi-path reception does not adversely affect the received quality of DVB
television transmissions (DVB is digital video broadcasting), unless signal levels are very
low. Received reflected signals can actually increase the received signal strength/quality.
Summary
As demolition and construction at the site are due to occur at a time after the analogue to
digital television transition, television interference due to reflection effects will be largely
eliminated/minimised. This is because DVB transmissions have an increased immunity to
multi-path received television signals compared to analogue.
4.0
AFFECT OF DEVELOPMENT CONSTRUCTION UPON TELEVISION
RECEPTION
During the primary construction phase of the project, cranes are likely to be utilised. Such
equipment will be manufactured utilising steel beams and steel sections to form steel lattices
for crane jibs and steel plate/sheet for control cabins. Incident television signals will be both
reflected and reduced in magnitude/blocked as a result. Post April 2012 reflection effects
may be ignored. However, temporary shadow problems could occur within very localised
areas surrounding the development once crane heights, or the height of any other
predominantly metallic construction structure exceed that of the surrounding buildings. The
extent of any possible poor reception difficulties would be directly related to the number of
cranes used, their location/closeness to each other, their respective metallic masses and
proximity to residences in the area receiving television via an aerial. Television reception
quality is also likely to vary as moving cranes will cause shadow extents to vary in both
horizontal and vertical planes. Shadow zones resulting from fixed cranes (such as those
located within the centre of a building under construction) would be subject to less alteration,
although poor TV reception could continue for longer periods. In some instances acceptable
levels of TV reception may not be reinstated until cranes and the like have been removed.
Dependent upon the final shape/contours of any finished building facade, some interference
problems are likely to be reduced or even eliminated once a facade has been completed. This
is due to TV signals being able to flow more easily around the outside of a completed
-8-
Cont….
structure (diffract around) rather than being blocked and scattered by building structural
steelwork.
5.0
MITIGATION MEASURES
Drawing KT4 within appendix 4 is local map showing likely shadows from the Development
for Crystal Palace and Wooburn television transmitters. Shadow zone lengths and widths are
likely to be considerably less than worst case calculated due to diffraction effects around and
over the various structures at the Development. Also, as already mentioned under baseline
conditions (section 3.2): the Crystal Palace shadow passes along roads that are elevated above
the height of the future Development, therefore any shadow will be reduced in length as a
result. Assessment of electromagnetic shading is based on worst case assumptions for the
materials likely to be used within the construction of the Development and consideration of
their geometrical configurations. Allowance is made for potential shading from structures
comprising part of the Development, but none is made for any metallic structural surfaces or
considerations of shading from any nearby buildings unrelated to the Development. In order
to more accurately ascertain whether the Development may or may not be responsible for any
future terrestrial TV interference, it will be necessary to carry out a pre-build survey to
measure ambient levels of TV transmissions within areas of possible signal degradation. The
following actions are recommended:
*
Carry out a TV signal strength/quality survey prior to construction of the Development
within areas surrounding the Development that are identified as possibly suffering
future signal degradation.
*
If any complaints of poor TV reception are received anytime up to practical
completion of the Development, a further TV signal strength/quality survey would be
carried out.
*
Survey results to provide reference levels that will be used to determine whether the
Development has had any significant affect upon TV reception.
*
The extent of TV signal degradation will provide the basis of recommendations for
mitigation of any poor signal quality.
*
Expected actions required to reinstate any areas of poor signal quality include
increasing the height of an aerial or moving it; the installation of a new higher gain
aerial and/or signal booster; or rotation of aerials to strongest local transmitter; or
alternatively, to view all channels via cable (which does exist at a number of locations
along the Crystal Palace shadow zone); or view via satellite; or possibly via the use of
an ADSL (asymmetric digital subscriber line) telephone line as an ancillary service
(some service providers include broadband plus a digital TV package). In some
circumstances the interference will be extremely localised and relocating the receiving
antenna at another point on a building or, increasing its height may be all that is
-9-
Cont….
required to improve received signal strength sufficiently. In extreme situations,
(although unlikely), if a number of households were adversely affected (the most
likely location would be residences very close to the Development within the future
Crystal Palace shadow), the cost effectiveness of a local cable link (which may already
exist anyway); satellite as already mentioned or, alternatively, the installation of a
local television repeater station may warrant consideration. The last mitigation option
is very unlikely to be necessary.
*
If a second survey indicates any significant deterioration of signal strength which can
be shown to be directly attributable to the Development, and complaints of poor TV
reception have also been made, measures for mitigation will be provided in agreement
with the local planning authority.
5.1
Alternative Television Transmitter Locations
If there were any problems related to poor signal strength along any parts of the predicted
shadow zones for the Crystal Palace transmitter, it may be necessary to boost the signal
strength. If a received signal is only poor within a shadow zone (i.e. not eliminated entirely),
then it should be possible just to install a local amplifier and if necessary change an existing
standard aerial for a high gain version. However, if signals are lost altogether, then some
aerials may have to be realigned to another transmitter. Locations and distances of possible
alternative transmitters are indicated below:Transmitter
Approximate direction (from site)
Distance
Wooburn
Reigate
Chepping Wycombe
High Wycombe
North 24 degrees East
South 52 degrees East
North 6 degrees West
North 13 degrees West
6.6 km
47.5 km
9.8 km
13.1 km
Reigate will provide a full version of ‘Freeview’ via 6 multiplexers. All other listed
transmitters will only provide a basic Public Service limited version of ‘Freeview’ via 3
multiplexers. Refer to section 2.1 for a list of channels/programmes provided.
NOTE: For satisfactory television reception, all of the above transmitters will require
amplified extra hi-gain receive aerials.
6.0
CELLULAR COMMUNICATIONS
The Ofcom data base indicates that there are a number of base stations and other types of
cellular transmitters/receivers near the Development. The following is a summary of those
within approximately 200 m:Operator/Site ref
Vodafone/1277
Transmission
Mast Height
GSM900/1800
34.5 m
-10-
Location
Off Nicholsons lane.
Cont….
T Mobile/7139
3/SL6081
Orange/BRK005
3/SL6291
T Mobile/91227
T Mobile/91227
GSM1800
3G
GSM1800
3G
GSM1800
3G
3m
9m
19 m
34.3 m
22 m
23.2 m
Off Nicholsons lane.
Keys Place.
Off Park Street.
Off York Road.
Off York Road.
Off York Road.
Those Operators listed at the same locations operate from a single site. All bar the operator at
Keys Place are located at least 100m from the Development. The Keys Place operator is
indicated as being at least 50 m from the Development. During the site visit only two of the
base stations could be seen. All should be far enough away from the Development to allow
their transmissions to be able to freely propagate around (and to a certain extent over) the
Development due to some diffraction effects. Many base stations have a communicating
microwave dish, although none could be seen during the site visit. Therefore the magnitude
of their expected negative impact upon the site (and vice versa) is anticipated to be negligible.
Summarising
Communications transmissions are unlikely to be significantly impaired by the Development.
All base stations are indicated as being sufficiently far enough away from the Site perimeter
to allow cellular telephone transmissions to freely propagate before encountering the
Development. The proposed sizes/heights and the materials that will be used within the
construction of the Development are unlikely to significantly adversely affect local cellular
communications signal coverage.
7.0
CONCLUSION
The proposed Development will have no significant impact upon:*
broadcast radio reception;
*
satellite television reception;
*
terrestrial television reception in all directions apart from transmissions incident upon
south easterly and northerly facing elevations of the proposed Development;
*
cellular telephone communications.
Electromagnetic shadows will be created to the north west and to the south west of the
Development. All will be relatively narrow and short.
If any television reception problems were to arise either during construction or upon practical
completion, in many instances the installation of a new higher gain aerial and/or signal
booster; or Moving/increasing the height of an aerial; or rotating receive aerials towards the
-11-
Cont….
strongest local transmitter may be all that is required to reinstate signal quality.
Alternatively, all channels could be viewed via cable (which is available along the Crystal
Palace shadow, and may also be very close to the site) or satellite.
Quantification/mitigation of effects will comprise:
*
TV signal strength/quality survey carried out prior to construction. TV signal
strength/quality survey carried out upon practical completion of the Development (but
only if any complaints of poor TV reception are received during construction).
*
Survey data will be utilised to determine whether there is any significant deterioration
of TV signal strength, and whether it is directly attributable to the Development.
*
Mitigation measures in many cases will only require the installation of a new higher
gain aerial and/or signal booster; or moving/increasing the height of an aerial; or
rotating a receive aerials towards the strongest local transmitter. For any locations of
very poor signal strength, it may be necessary for another form of television reception
to be provided (typically, utilise existing cable in the area, or install satellite).
Stephen Austin.
B.Sc., C.Eng., F.I.E.E., F.C.I.B.S.E. (Director)
-12-
APPENDIX No 1.
LOCATIONS AND TECHNICAL INFORMATION FOR
TELEVISION TRANSMITTERS SERVING MAIDENHEAD.
N
The Kings Triangle development will comprise retail, residential and commercial. The highest points of Buildings NB1-NB6 will
vary in height from 37.6 m AOD for NB6, up to 57.7 m AOD for NB3. Ground level for the development is +27.5 m. Parts of
the development will exceed the height of surrounding buildings, therefore there may be the potential for some television interference.
Wooburn Transmitter: 6.6 km away.
OS co-ordinates: SU916873.
Direction: North 24 degrees East of site.
Height of mast: 144 m AOD.
Transmitter provides low power digital
television via three public services low
power multiplexers (reduced freeview).
Power: 20 W per multiplexer.
Transmitter is a relay of Crystal Palace
Wooburn
NB1
+43.6 max
NB5
+43.6 max
+36.6 max
.5
+35
Ground level +27.5 m
+38.55 max
max
NB6
+37.6 max
NB2
+43.6 max
+41.5 max
NB3
+49.6 max
NB4
+50.75 max
NB3
+53.7 max
NB3
+53.65 max
+57.7 max
Kings Triangle Development
Crystal Palace
Crystal Palace Transmitter: 47.5 km away.
OS co-ordinates: TQ339712.
Direction: South 78 degrees East of site.
Height of mast: 330 m AOD.
Transmitter provides high power digital
televison via six multiplexers (full Freeview).
Power: 200 kW per multiplexer
Transmitter also provides national,
local and digital radio.
Project: Kings Triangle Development, Maidenhead - Telecommunications EIA.
Scale: NTS
Drawing Ref: KT1
Date: 30/08/12
Title: Locations/Technical Data For Main Television Transmitters Serving The Area.
EMC
C
M
Electro
agnetic
CONSULTANTS LTD.
ompatibility
Stebbing Hall, Lubberhedges Lane, Stebbing, Essex, CM6 3BU.
Telephone: 01371 856 964. Email: info@emc-consultants.co.uk
APPENDIX No 2.
WORST CASE LIKELY SHADOWS CAUSED TO EACH
TELEVISION TRANSMITTER.
N
The overall shadow will be propagated
in a direction North 78 degrees West.
Shadow lengths and widths will be
less than stated due to diffraction
effects around/over each structure.
36 m
NB1
+43.6 max
NB5
+43.6 max
+36.6 max
Ground level +27.5 m
+38.55 max
+3 5
ax
.5 m
The overall shadow will be a maximum of 4.5 km
long and 192 m wide. Individual elements will vary
both in width and length. A minor part of the shadow
will be a maximum of around 2.7 km long/36 m wide
and will be due to blocks NB1/NB5. The bulk of the
shadow will be due to blocks NB3/NB4 and will be
a maximum of around 4.5 km long and 156 m wide
NB6
+37.6 max
NB2
+43.6 max
+41.5 max
NB3
+49.6 max
NB4
+50.75 max
NB3
+53.7 max
NB3
+53.65 max
+57.7 max
NOTE: Building NB6 will not contribute to
the shadow
Crystal Palace
Project: Kings Triangle Development, Maidenhead - Telecommunications EIA.
Scale: NTS
Drawing Ref: KT2
Date: 31/08/12
Title: Electromagnetic Shadows Due To Crystal Palace Television Transmitter.
EMC
C
M
Electro
agnetic
CONSULTANTS LTD.
ompatibility
Stebbing Hall, Lubberhedges Lane, Stebbing, Essex, CM6 3BU.
Telephone: 01371 856 964. Email: info@emc-consultants.co.uk
N
Wooburn
The overall shadow will be propagated
in a direction South 24 degrees West.
Shadow lengths and widths will be
less than stated due to diffraction
effects around/over each structure.
NB1
+43.6 max
NB5
+43.6 max
+36.6 max
+38.55 max
+3 5
Ground level +27.5 m
ax
.5 m
NB6
+37.6 max
NB2
+43.6 max
+41.5 max
NB3
+49.6 max
80 m
NB4
+50.75 max
NB3
+53.7 max
NB3
+53.65 max
+57.7 max
The overall shadow will be a maximum of 1.9 km
long and 157 m wide. Individual elements will vary
both in width and length. Approximately half of the
shadow will be a maximum of around 1.1 km long/
80 m wide and will be due to blocks NB1/NB2.
The remaining part of the shadow will be due to blocks
NB3/NB4 at a maximum of around 1.9 km long and
77 m wide
NOTE: Building NB6 will not contribute to
the shadow
Project: Kings Triangle Development, Maidenhead - Telecommunications EIA.
Scale: NTS
Drawing Ref: KT3
Date: 03/09/12
Title: Electromagnetic Shadows Due To The Wooburn Television Transmitter.
EMC
C
M
Electro
agnetic
CONSULTANTS LTD.
ompatibility
Stebbing Hall, Lubberhedges Lane, Stebbing, Essex, CM6 3BU.
Telephone: 01371 856 964. Email: info@emc-consultants.co.uk
APPENDIX No 3.
TELEVISION SHADOW ZONES SUPERIMPOSED ONTO
LOCAL AREA MAP.
The Crystal Palace shadow zone could be up to 192 m wide/2.67-4.5 km long maximum,
and be propagated in a direction north 78 degrees west. Diffraction effects over and
around the structures will considerably reduce stated shadow dimensions.
The Wooburn shadow zone could be up to 157 m wide/1.1-1.9 km long maximum,
and be propagated in a direction south 24 degrees west. Diffraction effects over
and around the structures will considerably reduce stated shadow dimensions.
Location of Kings Triangle Development
KINGS TRIANGLE DEVELOPMENT, MAIDENHEAD - TELECOMMUNICATIONS EIA
Television shadow zones. Drawing ref: KT4. September 2012.