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Cumulative Radiated Emissions From Metallic Broadband Data Distribution Systems. Dr I D Flintoft Dr A D Papatsoris Dr D Welsh Prof A C Marvin York EMC Services Ltd. University of York. Scope. ionosphere. Sky Wave. 3-30 MHz. Space Wave. 0.1-30 MHz. Ground Wave. 0.1-3 MHz. London.

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cumulative radiated emissions from metallic broadband data distribution systems

Cumulative Radiated Emissions From Metallic Broadband Data Distribution Systems

Dr I D Flintoft

Dr A D Papatsoris

Dr D Welsh

Prof A C Marvin

York EMC Services Ltd.

University of York

scope
Scope

ionosphere

Sky Wave

3-30 MHz

Space Wave

0.1-30 MHz

Ground Wave

0.1-3 MHz

London

Rome

Near Field

suburban

rural

average UK ground

0 km

5 km

200 km

1500 km

contents
Contents
  • Overview of PLT and xDSL technologies
  • Modelling methodology
  • RF launch models and measurements
  • Sky wave propagation of PLT & VDSL
  • Ground wave propagation of ADSL &VDSL
  • Spectrum management
  • Conclusions
spectrum and technologies
Spectrum and Technologies

30 kHz

300 kHz

3 MHz

30 MHz

Low Frequency (LF)

Medium Frequency (MF)

High Frequency (HF)

Ground Wave

Sky Wave

Space Wave

ADSL (25 kHz-1.1 MHz)

VDSL (1.1-30 MHz)

DPL (2.9 & 5.1 MHz)

power line telecommunication plt
Power Line Telecommunication (PLT)
  • Propriety systems
  • PowerNET: 9-95 kHz (EN50065)
  • Digital Power Line (DPL)
  • Frequencies: 2.2-3.5 & 4.2-5.8 MHz
  • 2 Mbit/s channels demonstrated
  • Uses low voltage (LV) network
mains network topology
Mains Network Topology

DPL Cell

= Data Terminal

Medium Voltage (MV) Network

Low Voltage (LV) Network

Secondary

Substation

Transformer

50 single phase services off each distributor

Primary

Substation

Transformer

To High Voltage (HV) Network

250 m

physical structure of lv network

CU

Physical Structure Of LV Network

Armoured Cable

  • Underground and overhead distribution
  • Armoured cable
  • Conditioning units (CU) may be used

Conditioning Unit (CU)

LV network

Network

internal mains network

MV network

CU

LV network

substation

data port

data network

input power for a dpl cell
Input Power For A DPL Cell
  • DPL cell – coherently excited segment of network
  • Physical channel shared by all users in cell
  • Multi-user access scheme: TDMA
  • Power spectral density from terminal = –40 dBm/Hz = 1 mW in 10 kHz bandwidth
  • 10 kHz = typical HF AM radio bandwidth
digital subscriber line xdsl
Digital Subscriber Line (xDSL)
  • Overlay technology enabling broadband services on telephony metallic local loop
  • Symmetric and asymmetric upstream/downstream data rates
  • Data rates up to 50 Mbit/s (VDSL)
  • CAP, QAM, DMT modulation techniques
telecommunications network
Telecommunications Network

overhead distribution

overhead drop

MDF

underground distribution

cross connect

cross connect

50 m

1.5 km

footway junction box

exchange

4 km

300 m

= Data Terminal

underground drop

xdsl varieties
xDSL Varieties

FTTEx = Fibre To The Exchange, FTTCab = Fibre To The Cabinet

physical structure
Physical Structure

Balance of UTP

  • Bundles of unshielded twisted pair (UTP)
  • Designed for POTS – up to a few kHz
  • Cable balance – degrades with frequency
  • Network balance – interfaces
  • Splitters
  • Three wire internal cabling

(New cable under controlled conditions)

modelling methodology
Modelling Methodology
  • Identify coherently excited network elements
  • Determine the radiative characteristics of these network elements
  • Construct an effective single source for cumulative emissions – pattern & power
  • Use these effective sources in propagation calculations
rf launch models
RF Launch Models
  • Numerical Electromagnetics Code
  • Sommerfeld-Norton lossy ground model
  • Common-mode current model
  • Predict antenna gain and radiation efficiency of the network elements
  • Underground cables not considered  these will be conservative estimates
network elements
Network Elements

PLT

House Main Ring

Street Lamp

10 m

3N m

xDSL

6 m

Overhead Drop (Splitter)

Overhead Drop (No Splitter)

N Storey Building (N=1,2,…, 10)

antenna patterns for xdsl
Antenna Patterns For xDSL
  • At low frequencies (ADSL) patterns are omni-directional
  • Model using an effective short vertical monopole

Normalised gains at 1 MHz

validation measurements
Validation Measurements
  • Measurements on UTP aerial drop cable
  • Balanced and unbalanced connections
  • Results used to calibrate the NEC launch models
cumulative radiated power
Cumulative Radiated Power
  • Digital data transmission is a random process which can be modelled as a noise source
  • Cumulative field from incoherently excited network elements calculated by noise power addition (REC. ITU-R PI.372-6)
  • Phase effects ignored
sky wave propagation
Sky Wave Propagation
  • Time of day
  • Time of year
  • Transmitter antenna power
  • Transmitter antenna pattern
  • Transmitter antenna position
  • We have considered transmission on a February evening
its institute for telecommunication sciences hf propagation software
ITS (Institute For Telecommunication Sciences) HF Propagation Software
  • Package caters for area coverage or point to point predictions
  • Allows choice of several propagation models: ICEPAC, VOACAP, REC533
  • We chose to use REC533 model based on advice from RAL and the ITU
  • Launch power and antenna pattern
dpl source power for london
DPL Source Power For London
  • Power in 10 kHz bandwidth: 1 mW
  • Area: 2500 km2
  • Size of DPL cell: 0.28 km2 (diameter 600 m)
  • Total number of cell: 2500/0.28  8925
  • Total input power: 8925  1 mW = 8.9 W  40 dBm
  • Antenna gain: –15 dB
  • Total radiated power: 40 – 15 = 25 dBm
coverage of london at 5 1 mhz
Coverage Of London At 5.1 MHz

0

Subtract 15 dB to read true dBmV/m, .i.e. for 15 dBmV/m read 0 dBmV/m

London cumulative antenna

Isotropic antenna

cumulative dpl sky wave from many urban areas
Cumulative DPL Sky Wave From Many Urban Areas
  • Since the coverage from each urban area is Europe wide we need to sum the field from many urban areas
  • Major sources over UK would be the Ruhr area of Germany, London, Birmingham and Manchester
  • Total field over UK due to these major sources plus other major UK cities is predicted to be between 5 and 11 dBV/m
  • Established ITU noise floor is 8 dBmV/m (rural area)
slide27

VDSL Source Power For London

  • Drop model without internal cables
  • Average of 1000 homes per km2
  • 25 % technology penetration
  • Antenna gain of –25 dB (corresponds to 20 dB cable balance parameter)
  • Terminal input power –60 dBm/Hz or –20 dBm/10kHz
  • Total radiated power 13 dBm (20 mW)
coverage of london at 8 mhz
Coverage Of London At 8 MHz

Subtract 27 dB to read true dBmV/m, .i.e. for 15 dBmV/m read -12 dBmV/m

slide29

Cumulative VDSL Sky Wave From Many Urban Areas

  • Sum powers from major UK cities and Ruhr area of Germany
  • Cumulative field over UK at 8 MHz is –6 dBmV/m in 10 kHz bandwidth
  • Established ITU noise floor is 8 dBmV/m (rural area)
  • 10 dB lower than DPL
groundwave propagation theory 1
Groundwave Propagation Theory (1)
  • Sommerfeld (1909), Norton (1936, 1937)
  • (V) fields >> (H) fields
  • A(d,f,,) for (V) polarised fields
  • Attenuation factor calculated according to ITU-R P.368, originally developed by GEC
groundwave propagation theory 2
Groundwave Propagation Theory (2)
  • The E-field formula applies to a linear short (h<<) radiative element
  • NEC used to determine the equivalent FMPt of radiative structures associated with xDSL
  • Calculations done for upstream and downstream mode of transmission
  • Radiation patterns omnidirectional for ADSL
  • Balance, attenuation of UTPs
calculation strategy of cumulative emissions 1
Calculation strategy of cumulative emissions (1)
  • Electric fields Ei from uncorrelated individual sources add incoherently, i.e.,
  • A: area enclosing all radiating sources in m2
  • pi: percentage of building type associated with ith radiating source
  • Di: density of installations per unit area
  • Mpi: fraction of market penetration
  • Li: fraction of installed lines used concurrently
calculation strategy of cumulative emissions 2
Calculation strategy of cumulative emissions (2)
  • Step 1. Definition of radiating medium, A=25km2
  • The RSS summation, lends itself to an active spreadsheet implementation
calculation strategy of cumulative emissions 3
Calculation strategy of cumulative emissions (3)
  • Step 2. Definition of makeup of city buildings
calculation strategy of cumulative emissions 4
Calculation strategy of cumulative emissions (4)
  • Step 3. Specify reference radiating efficiencies, balance and attenuation at frequencies of interest for upstream and downstream transmission
calculation strategy of cumulative emissions 5
Calculation strategy of cumulative emissions (5)
  • Step 4. Define the appropriate transmission spectral mask, i.e., for ADSL PSD=-34.5dBm/Hz (upstream 138-276 kHz), PSD=-36.5dBm/Hz (downstream 138-1104 kHz).
  • Step 5. Calculate the unattenuated electric field for each radiative element, i.e.,
calculation strategy of cumulative emissions 6
Calculation strategy of cumulative emissions (6)
  • Step 6. Calculate the appropriate electric field correction factor for each radiative element.
  • Step 7. Evaluate the total electric field by performing the RSS summation over all xDSL installations.
test cases and results adsl 1
Test cases and results ADSL(1)
  • Case 1. A=25 km2, bal=40dB, Mpi=20%, Lui=10%
test cases and results adsl 2
Test cases and results ADSL(2)
  • Case 2. A=25 km2, bal=30dB, Mpi=50%, Lui=10%
test cases and results adsl 3
Balance

Radiation levels increase by a margin equal to the balance difference in dB.

E(bal2)=E(bal1)+bal, bal= bal1 - bal2

Market Penetration

E(M2)=E(M1)+M, M=10log(M2/M1)

Distance

-20 dB/decade for f(100kHz - 400kHz)

-25 dB/decade for f(600kHz - 800kHz)

-30 dB/decade for f(1000kHz)

Test cases and results ADSL(3)
summary of results for adsl
Summary of results for ADSL
  • Emission electric fields resulting from cumulative ATU-R upstream and MDF downstream transmissions at distance 1km away from the effective emission centre.(M=20%, L=10%, Typical bal=30 dB)
graph of current noise floor itu r p 372
Graph of current noise floor, ITU-R P.372
  • Median noise electric field at a receiver with bandwidth 10kHz at 12 noon in a residential location in the central UK.
adsl and current noise floor
ADSL and current noise floor
  • No likely change to the established median electric noise field for the well balanced city (bal=50 dB) model at d>1km away from the MDF centre.
  • For the typically balanced city model ADSL fields are predicted above the current noise floor (cnf)
    • ATU-R field > cnf by 5dB - 10dB at d<2km
    • MDF field > cnf by 10dB - 20dB at d<3km
  • For distances > 10km, ADSL<cnf
summary of results for vdsl
Summary of results for VDSL
  • Emission electric fields resulting from cumulative NT-LT upstream and LT-NT downstream transmissions at distance 1 km away from the effective emission centre. (M=20%, L=20%, Typical bal=20 dB.)
vdsl and current noise floor
VDSL and current noise floor
  • No likely change to the median electric noise field for the well balanced small city (bal=30 dB) model at d>1km away from the emission centre.
  • For the typically balanced city model VDSL fields are predicted above the current noise floor (cnf):
    • NT-LT field > cnf by 10dB - 20dB at d<1.5km
    • LT-NT field > cnf by 5dB - 15dB at d<1.5km
  • For distances > 5km, VDSL<cnf.
  • Radiation diagrams of radiative elements give rise to significant space wave component.
spectrum management issues
Spectrum management issues
  • AM broadcasting in band 6 (MF)
    • For ‘good’ quality reception
      • 88dBV/m, 74dBV/m, 60dBV/m for typical city/industrial, city/residential and rural/residential areas, respectively.
    • AM transmitter serving designated metropolitan area enclosed by a 50km radius in UK.
      • =15, =10mS/m, Pt=10kW
      • PR=30dB, thus interfering field 44dBV/m
      • xDSL(d>1km)< 44dBV/m, but Gaussian in nature
    • For rural locations near xDSL fields important
spectrum management issues1
Spectrum management issues
  • Digital MF broadcasting
    • DRM consortium preliminary specification
      • Narrow bandwidth (max 10kHz), thus:
        • very efficient source coding scheme [MPEG-4 AAC]
        • multi-carrier modulation to overcome multipath, Doppler, [OFDM]
        • high state linecode modulation scheme, [QPSQ, 16QAM, 64QAM depending on service requirements]
      • Protection ratios:
        • AM interfered with by DM, [f/kHz=0, PR=36dB]
        • DM interfered with by AM, [f/kHz=0, PR=0dB]
        • DM interfered with by DM, [f/kHz=0, PR=15dB]
spectrum management issues2
Spectrum management issues
  • Digital MF broadcasting
    • DRM consortium preliminary specification
      • Carrier-to-noise ratios:
      • C/N of 24dB for BER=1x10-5 is at least required.
spectrum management issues3
Spectrum management issues
  • Power savings of 4-8dB can be made by DM transmitters, for same daytime coverage.
  • xDSL(d<1km)>C/N, near xDSL ?
  • assessment of xDSL mux and mod techniques
spectrum management issues4
Spectrum management issues
  • AM transmitters to be phased out by 2020
    • Lower PR could be used, 10-15 dB less than the currently assumed for AM, thus:
      • reduced radiation of digital transmitter power
      • much quieter EM environment
    • If xDSL>planned interference value:
      • DM power must increase (financial implications?)
      • concerted actions of broadcasting authorities to restore the service
      • xDSL near fields at remote locations?
xdsl and aeronautical services
xDSL and aeronautical services
  • Services likely to be affected are:
    • Radiolocation & mobile communications
  • NEC simulations show a significant space-wave propagation component for f>1MHz
    • most radiation is directed towards elevation angles ranging between 30 and 60 degrees
  • Space wave stronger than ground wave
xdsl and government services
xDSL and government services
  • Services likely to be affected are:
    • Military mobile communications in HF
      • low data rate systems work even 8 dB below ambient noise in a 3 kHz receiver bandwidth
      • 9.6 kbps and above data rates at 3 kHz bandwidth are standardized requiring a minimum 33 dB C/N ratio
      • 3 - 5MHz, critically important for short/medium length communications paths at night when other HF frequencies do not work
conclusions 1
Conclusions (1)
  • Active spreadsheet tool for RA
  • Preliminary calculations suggest:
    • AM and DM broadcasting may be unfavourably affected
      • xDSL(d<1km) & selected areas
      • xDSL near fields need to be assessed
      • lower PR for DM mean very low power Tx resulting to a much quieter EM environment, fossil fuel savings and reduction in greenhouse gases
conclusions 2
Conclusions (2)
  • Preliminary calculations suggest:
    • Aeronautical services may be unfavourably affected
      • xDSL(d<1km) & selected areas
      • Further study is needed
        • cumulative space wave emissions
        • technical and operational characteristics of aeronautical NDBs, current and future mobile communications
    • Government services may be unfavourably affected
      • Mobile communications
      • Further study is needed
conclusions 3
Conclusions (3)
  • It is therefore provisionally suggested that xDSL emissions should be contained at a maximum level of 20dB above the established radio noise floor near the effective radiation centres (d=1km). (For the UK lower values than those in the ITU-R P.372 can be used.)
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