Broadband Over Power Line

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Broadband Over Power Line
FCC Notice of Proposed Rulemaking
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Proposed Rules

• BPL continues to be legal under Part 15
• FCC chose not to increase or decrease radiated
  emissions limits
• Carrier-current device must meet the Part 15
  limits for intentional emitters
• On HF, 30 uV/m at 30 m
• Is this an appropriate level for a broadband
  device radiating from overhead power lines?
• Part 15 will continue to permite BPL under its
  Verification authorization
• Is this suitable for the EMC environment of
  access BPL?
• FCC chose not to change the provision that a Part
  15 device must not cause harmful interference

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30 uV/m (29.54 dBuV/m)

• Strong local signal
• Will result in received signal level of -100 dBW
  to nearby receivers on spectrum BPL uses
• Local noise levels on HF have been measured by
  ARRL as low as 10 dBuV/m in quiet parts of a
  frequency band
• BPL system radiates along length of power line
  for about a half mile down the line
• Radiates across up to tens of MHz of spectrum

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Power Line as Radiator
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Test Methods

• Ideally, testing could be done to perfection
• In-situ measurements difficult
• FCC wants a reasonable but reasonably accurate
  test method
• Hundreds of measurements on each individual
  installation not practical
• A good compromise is better than the alternatives

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Use of Loop Antenna
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Fields vs Height

• NPRM wants to make measurements at 1 meter height
• What extrapolation factor can be used to estimate
  fields at greater height?
• No perfect extrapolation
• H field increases near perfect ground
• Lossy ground loses energy

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EZNEC Calculation
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Testing 3 Orthogonal Axes

• FCC says to orient loop vertically and rotate for
  maximum
• Does not combine measurement from 3 axes
• This does not measure one polarization plane at
  all
• X, Y and Z

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X, Y and Z
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Near vertical ground wire
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Fields vs Distance

• FCC Part 15 specifies field strength at 30 uV/m
  at 30 m
• Their recommended test practice calls for testing
  to be done 10 meters horizontally from line
• This is then corrected for slant-range distance
  to line using 40 dB/distance decade
• This is wrong for large radiators

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What frequency steps?
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Three typical installations
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To do

• Measurements in BPL areas of X, Y and Z H field
  axes
• FCC asking for advice on test methods
• Can C63 develop or support a simplified test
  procedure?
• Should it be FCCs or should C63 develop a
  different one?
• Power Society/Standards Association holding
  meeting in July in Denver
• Asking if they should develop a BPL standard

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What statement for todays report?