Transcript Introduction to EMC

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
Rome
Near Field
suburban
rural
average UK ground
0 km
5 km
200 km
1500 km
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
30 kHz
300 kHz
Low Frequency (LF)
3 MHz
Medium Frequency (MF)
30 MHz
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)
•
•
•
•
•
•
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
DPL Cell
= Data Terminal
Medium
Voltage (MV)
Network
Low Voltage (LV) Network
Secondary
Substation
Transformer
Primary
Substation
To High Transformer
Voltage
(HV)
Network
50 single phase services off each distributor
250 m
Physical Structure Of LV
Network
•
•
•
Underground and overhead
distribution
Armoured cable
Conditioning units (CU)
may be used
internal
mains
network
CU
substation
data
network
Conditioning Unit (CU)
LV network
Network
MV
network
Armoured Cable
LV network
CU
data port
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)
• 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
overhead distribution
overhead drop
MDF
underground
distribution
cross
connect
1.5 km
exchange
4 km
= Data Terminal
cross
connect
50 m
footway
junction box
300 m
underground drop
xDSL Varieties
Technology
Deployment
Frequency
POTS
Splitter
Cable
ADSL
FTTEx
25 kHz - 1.1MHz
Yes
single pair
ADSL Lite
FTTEx
25 kHz - 552 MHz
No
single pair
VDSL
FTTCab
0.3 - 30 MHz
Yes?
single pair
SDSL
FTTEx
DC – 784 kHz
No
multi pair
HDSL
FTTEx
DC – 784 kHz
No
multi pair &
single pair
FTTEx = Fibre To The Exchange, FTTCab = Fibre To The Cabinet
Physical Structure
•
•
•
•
•
Bundles of unshielded twisted pair
(UTP)
Designed for POTS – up to a
80
few kHz
60
Cable balance – degrades with
40
frequency
Network balance – interfaces
20
Splitters
0
0
Three wire internal cabling
Balance of UTP
(New cable under controlled
conditions)
Balance (dB)
•
2
4
6
Frequency (MHz)
10
Input Power For xDSL
ADSL
VDSL (FTTCab)
Downstream
Upstream
Downstream
Upstream
Frequency
(MHz)
0.138 - 1.104
0.138 - 0.276
1.104 - 10.0
1.104 - 10.0
PSD
(dBm/Hz)
-36.5
-34.5
-60
-60
Power in
10 kHz (mW)
2.2
3.5
0.01
0.01
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
•
•
•
•
•
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
PLT
House Main Ring
Street Lamp
10 m
3N m
xDSL
6m
Overhead Drop
(Splitter)
Overhead Drop
(No Splitter)
N Storey Building
(N=1,2,…, 10)
Antenna Patterns For xDSL
• At low frequencies
0
60
120
180
240
300
360
-0.1
Field Strength (dBuV/m)
•
(ADSL) patterns are
omni-directional
Model using an
effective short vertical
monopole
Azimuth (Degrees)
-0.3
Drop 1
-0.5
Drop 2
-0.7
Storey 2
Storey 5
-0.9
Storey 10
-1.1
-1.3
-1.5
Normalised gains at 1 MHz
Validation Measurements
•
•
•
Measurements on
UTP aerial drop cable
Balanced and
unbalanced
connections
Results used to
calibrate the NEC
launch models
100  load
Plastic pole
6m
POTS UTP
Balun
130 m
Coaxial cable feed
Receiver
Measured Balance Parameters
Frequency
(MHz)
Measured Efficiency
(dB)
Unbalanced
Connection
Balanced
Connection
2.2
-55
-79
3.0
-46
4.3
NEC
Efficiency
(dB)
Effective Balance For
NEC Model (dB)
Unbalanced
Connection
Balanced
Connection
-19
36
60
-74
-17
29
57
-47
-87
-14
33
73
5.9
-40
-79
-11
29
68
7.0
-30
-
-10
20
-
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
•
•
•
•
•
•
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
• 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
Cumulative DPL Antenna Pattern
enclosing
hemisphere
Source patterns shown
as hemispheres
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
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
•
•
•
•
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 dBmV/m
Established ITU noise floor is 8 dBmV/m (rural
area)
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
Subtract 27 dB
to read true
dBmV/m, .i.e.
for 15 dBmV/m
read -12
dBmV/m
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)
•
Sommerfeld (1909), Norton (1936, 1937)
E
•
•
•
FM Pt
A(d , f ,  r ,  , polarisation)
d
(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)
•
•
•
•
•
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)
Electric fields Ei from uncorrelated individual
sources add incoherently, i.e.,
m
E  A pi Di M pi Li Ei2
i 1
• 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)
•
•
m
E  A pi Di M pi Li Ei2
i 1
Step 1. Definition of
radiating medium,
A=25km2
The RSS summation,
lends itself to an active
spreadsheet
implementation
Calculation strategy of
cumulative emissions (3)
•
Step 2. Definition of makeup of city buildings
Di
M akeup of radiating area
M pi
pi
density
max l ine
market
[%]
l ines/m2
number
penetration
i
Lui
radiative subscriber concurrent concurrent
el ement
l ines
usage %
l ine use
5,00%
0,005
6250
20,00%
drop1
1250
10,00%
125
Percentage of terraced houses
31,00%
0,008
62000
20,00%
drop1
12400
10,00%
1240
Percentage of semi-det. houses
41,00%
0,006
61500
20,00%
drop1
12300
10,00%
1230
Percentage of detached houses
17,00%
0,003
12750
20,00%
drop2
2550
10,00%
255
Percentage of 1 storey buildings
1,70%
0,002
850
20,00%
storey1
170
10,00%
17
Percentage of 2 storey buildings
2,50%
0,002
1250
20,00%
storey2
250
10,00%
25
Percentage of 3 storey buildings
1,00%
0,003
750
20,00%
storey3
150
10,00%
15
Percentage of 4 storey buildings
0,50%
0,004
500
20,00%
storey4
100
10,00%
10
Percentage of 5 storey buildings
0,20%
0,005
250
20,00%
storey5
50
10,00%
5
Percentage of 10 storey buildings
0,10%
0,010
250
20,00% storey10
50
10,00%
5
Percentage of bungalow houses
146350
29270
2927
Calculation strategy of
cumulative emissions (4)
•
Step 3. Specify reference radiating efficiencies, balance and
attenuation at frequencies of interest for upstream and
downstream transmission
ATU-C customer end
Rad CF
dB
Att
[dB]
0
0
0
10
12
14
0
0
0
16
18
20
PSD
Frequency
[dBm/Hz]
[MHz]
-36,5
0,1
-36,5
0,2
-36,5
0,4
-36,5
-36,5
-36,5
0,6
0,8
1,0
Cable length
Balance
[dB]
drop1e
drop2e storey1e
0,006391 0,00586 0,001769
50
0,024381 0,022364 0,006746
50
0,091679 0,084213 0,025357
50
0,197467 0,181758 0,054553
50
0,339397 0,313297 0,093527
50
0,516229 0,47834 0,141679
50
1,0
Pt/Pin, [%]
storey2e storey3e
0,006632 0,012668
storey4e storey5e storey10e
0,020294 0,029506 0,099175
0,025278
0,094806
0,048256
0,180598
0,077249 0,112219
0,28848 0,418136
0,37559
1,384081
0,203306
0,347179
0,523571
0,386215
0,65749
0,988036
0,615251 0,889444
1,044215 1,505028
1,563975 2,246684
2,904588
4,834889
7,08051
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., P
Prad  t ref PinxDSL balanceref att
Pin
E1 (mV / m)  FM Prad (kW )
Calculation strategy of
cumulative emissions (6)
•
Step 6. Calculate the appropriate electric field
correction factor for each radiative element.
CF (dB)  20log(E1 (mV / m) / 300).
•
Step 7. Evaluate the total electric field by
performing the RSS summation over all xDSL
installations.
Test cases and results ADSL(1)
•
Case 1. A=25 km2, bal=40dB, Mpi=20%, Lui=10%
20
20
10
MDF electric field, [dBuV/m ]
ATU-R electric field, [dBuV/m ]
10
0
-10
-20
-30
0
-10
-20
-30
-40
-50
-60
-40
-70
-50
-80
1
10
25
50
75
100
200
300
400
500
1
Distance, [km ]
100 kHz
10
25
50
75
100
200
300
400
500
Distance, [km ]
200 kHz
400 kHz
600 kHz
800 kHz
1 M Hz
Test cases and results ADSL(2)
•
Case 2. A=25 km2, bal=30dB, Mpi=50%, Lui=10%
40
40
20
MDF electric field, [dBuV/m ]
ATU-R electric field, [dBuV/m ]
30
20
10
0
-10
-20
0
-20
-40
-60
-30
-80
-40
1
10
25
50
75
100
200
300
400
500
1
25
50
75
100
200
300
400
500
Distance, [km ]
Distance, [km ]
100 kHz
10
200 kHz
400 kHz
600 kHz
800 kHz
1 M Hz
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)
Summary of results for ADSL
Freq.
[MHz]
0.1
Small city
(York)
Typ.
Opt.
Large city
(Leeds)
Typ.
Opt.
27.67
7.67
35.45
0.2
26.91
6.91
34.69
Large city
(Leeds)
Typ.
Opt.
15.45
Freq.
[MHz]
0.4
Small city
(York)
Typ.
Opt.
28.44
8.44
36.22
16.22
14.69
0.6
24.86
4.86
32.64
12.64
0.8
21.20
1.20
28.98
8.98
1.0
17.94
-2.06
25.72
5.72
• 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
Noise electric field, [dBuV/m]
60,00
50,00
40,00
30,00
20,00
10,00
0,00
0,03
0,30
3,00
30,00
Frequency, [MHz]
•
Winter
Summer
Spring
A utumn
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
•
•
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
Freq.
[MHz]
1
Small city
(York)
Typ.
Opt.
Large city
(Leeds)
Typ.
Opt.
21.43
11.43
27.46
2
20.67
10.67
4
17.97
6
Large city
(Leeds)
Typ.
Opt.
17.46
Freq.
[MHz]
1
Small city
(York)
Typ.
Opt.
17.94
7.94
23.96
13.96
26.70
16.70
2
17.18
7.18
23.2
13.20
7.97
24.00
14.00
4
11.52
1.52
20.50
10.50
14.39
4.39
20.42
10.42
6
10.90
0.90
16.92
6.92
8
10.73
0.73
16.76
6.76
8
7.24
-2.76
13.26
3.26
10
7.07
-2.53
13.50
3.50
10
3.98
-6.02
10.0
0.0
• 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
•
•
•
•
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
• AM broadcasting in band 6 (MF)
– For ‘good’ quality reception
• 88dBmV/m, 74dBmV/m, 60dBmV/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 44dBmV/m
• xDSL(d>1km)< 44dBmV/m, but Gaussian in nature
– For rural locations near xDSL fields important
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 issues
• Digital MF broadcasting
– DRM consortium preliminary specification
• Carrier-to-noise ratios:
CHANNEL
MODEL
Channel 1
CHANNEL
TYPE
AWGN
Channel 2
Ricean with
delay
US
Consortium
CCIR poor
Channel 3
Channel 4
PROPAGATION
MODE
Ground Wave,
LF, MF
Ground Wave,
MF
Sky Wave, HF
Sky Wave, HF
C/N FOR
BER=1X10-4
14.9
16.0
22.7
21.7
• C/N of 24dB for BER=1x10-5 is at least required.
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 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
• Services likely to be affected are:
– Radiolocation & mobile communications
• NEC simulations show a significant spacewave 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
• 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)
• 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)
• 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)
• 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.)