Transcript BROADBAND OVER POWER LINE (BPL) SYSTEMS

Broadband Over Power Line
National Telecommunications
and
Information Administration
U.S. Department of Commerce
May 25, 2005
Scope

BPL in the Context of Power Line
Emissions*

Findings Of NTIA BPL Phase 1 Study*

Subsequent Technical Findings*

Framework of FCC BPL Rules

NTIA’s On-going Study Priorities
___________
*See www.ntia.doc.gov, publications, NTIA BPL Phase 1 Report and
Comments to FCC
2
BPL in the Context of Power
Line Emissions



Without BPL, power line emissions exceed
FCC Part 15 field strength limits and
interfere in some cases
Diagnosis and repair of noise emissions
can be time-consuming and costly
Some federal radio operators routinely
police local power lines for noise
emissions, diagnose high emission levels,
and work cooperatively with the utility or
electricity user to eliminate interference
3
Some Receiver Antennas are
Close to Power Lines
4
NTIA BPL Study Findings


NTIA Coordinated its studies with FCC/OET
BPL (and other) power line radiated emissions do
not emanate from a point source
• Multiple points sources (impedance discontinuities)
• Traveling wave modes of high radiation intensity

Measurements & modeling
• Radiation and local groundwave propagation - Numerical
Electromagnetics Code (NEC) ver. 4.1
• Local spacewave propagation toward aircraft – Matlab
model using NEC radiation predictions
• HF ionospheric propagation - VOACAP software

Phase 1 study addressed potential local
interference
5
Example NEC Analysis
(Spatial Distribution of E Field)
6
Distances From BPL Power Lines
Within Which Interference Is Likely
Desired Signal
Service
Level
LOW –
MODERATE
MODERATE HIGH
Land Mobile Station
125 m
55 m
Fixed or Base
Station (for Mobile)
770 m
450 m
Maritime Shipborne
Station
135 m
85 m
33 km
> 50 km
12 km
-
Aircraft
alt:
in Flight
alt.
6 km
12 km
7
NTIA Phase 1 Study Findings


Many interference prevention and
mitigation techniques exist: advance
consultations and BPL frequency agility
Greatest interference risks stem from
compliance measurement provisions:
• In situ measurement procedures not well
defined (ANSI C63 and CISPR 16 & 22)
• Irregular spatial distribution of field strength
greatly complicates compliance measurements
8
Subsequent Study Findings



Relatively high levels of field strength are
spatially confined
A practical compliance measurement procedure
for Access BPL systems can reliably identify the
field strength level that is not exceeded at 80%
of possible receiver antenna locations at the
specified measurement distance from the
radiating structure – this is the procedure that
was specified in the FCC Report & Order
Ionospheric propagation and aggregation of BPL
emissions is not a near-term issue: millions of
BPL devices can be deployed before the onset of
any such interference problem

Should not delay rulemaking for further study
9
Framework of FCC BPL Rules



Access BPL emission frequencies
must be fungible
Access BPL devices are subject to
certification
In-House BPL compliance
measurement procedures improved
via requirement to measure along
outdoor power service lines
10
NTIA’s On-Going Study Priorities


Update interference risk analyses
based on new FCC rules for Access
BPL systems
Provide additional guidance:
• Prevention of interference
• Suspected interference

Prevention of significant noise floor
increase via ionospheric propagation
11