**APPENDIX D**

**BROADBAND OVER POWER LINE**

**EMISSION MEASUREMENTS**

**D.1 INTRODUCTION**

This appendix presents measurements performed by NTIA's Institute for
Telecommunications Sciences (ITS) that quantified several aspects of BPL
signals. The measurements were conducted in three areas where BPL
systems are currently deployed for testing and are serving customers.
Access BPL was implemented on MV wires in all three areas and in-house
BPL was implemented on LV wires in two areas. Some access BPL was on
overhead wires and some is on underground wires, whereas, all of the
in‑house BPL was above ground except where, in some cases, there were
buried LV wires leading up to the houses. The objectives for the
measurements were to:

1.  Measure the received BPL signal power at points along power lines;

2.  Measure the received BPL signal power at various distances from
    power lines;

3.  Measure the received BPL signal peak, average and quasi‑peak levels
    for comparison;

4.  Measure the received BPL signal power at different antenna heights;
    and

5.  Measure the amplitude probability distributions (APDs) of the BPL
    signal.

The measurement system used for this testing is described in Section
D.2. Figures and tables of measured data are provided in Section D.3. In
section D.4 of this report, background information about APDs is
covered, and in Section D.5, gain and noise figure calibration is
described.

**D.2 THE MEASUREMENT SYSTEM**

The measurement system block diagram is shown in Figure D-1. An antenna,
positioned 10 meters above the ground atop a telescopic mast on the ITS
"RSMS‑4" measurement vehicle (Figure D-2) and 2 meters above the ground
on a tripod, was used to measure the received power. Four different
types of antennas were used. A small discone antenna over a small ground
plane was used to measure the electric fields above 30 MHz. Below 30
MHz, two shielded loops were used to measure the magnetic fields and for
the electric fields, a rod antenna over a small ground plane was used.
To measure the received power that is expected to be seen by a typical
land mobile radio, a 2.13 meter base‑loaded whip antenna was mounted on
the roof of a vehicle at an approximate height of 1.5 meters. The whips
were narrow‑band, so several of them were used to cover the measurement
frequencies. The signal from the antenna was split into two measurement
systems so that simultaneous measurements could occur and to minimize
switching instrument setups. A preselector was used on each system in
order to prevent an overload condition from occurring and improve the
sensitivity. Computers were used to control the measurement instruments
and store the data.

![](media/image1.wmf){width="5.191666666666666in"
height="4.533333333333333in"}

Figure D-1: BPL measurement system block diagram.

![](media/image2.wmf){width="6.229861111111111in" height="4.6875in"}

Figure D-2: Radio Spectrum Measurement System - 4 (RSMS-4)

The output of one of the preselectors was variously connected to a HP
8566 spectrum analyzer with a quasi‑peak detector, a vector signal
analyzer or a multi‑mode communications receiver. The receiver was used
to listen to the BPL signal in several demodulation modes and to assist
with distinguishing between BPL and other signals. The vector signal
analyzer was used to record the time‑waveform for future analysis.

**D.3 BPL MEASUREMENTS**

**D.3.1 Background on BPL Emissions Measurements**

This sub-section provides general information on the BPL emissions from
the three types of systems under test. These data are provided as an aid
to understanding the measurements presented in Sections D.3.2 -- D.3.6.

The BPL signal shown in Figure D-3 is representative of the weakest
(lowest power density) BPL signals for which data were recorded. That
is, nominal interference-to-noise ratio (I/N) levels had to exceed about
5 dB; otherwise no BPL signal level (I) was recorded[^1]. Thus, even
though much weaker BPL signal levels were measurable when turning the
BPL system on and off (i.e., I/N of -6 dB), measurements with I/N 5 dB
ensured that measured signals were unquestionably due to BPL emissions.

[System #1]{.underline}

This system used different frequency bands for signals on the MV and LV
wiring. Signal strength measurements were performed by acquiring
multiple traces from a spectrum analyzer centered on specific
frequencies with a zero span and a sampling detection mode. Trace data
were downloaded to a computer and later analyzed statistically using
Amplitude Probability Distributions (APDs). From these distributions,
the temporal statistics of the BPL signal were identified and the power
was determined as described in Section D.5. The signal power determined
from these distributions is expressed as "100%-duty-cycle" power and
represents the maximum power if the packet data were present 100% of the
time (i.e. signal pulses occurring back-to-back), as further explained
in Section D.4.0.

[System #2]{.underline}

The BPL signal used OFDM modulation with a carrier spacing of
approximately 1.1 kHz. BPL is transmitted only on the MV lines. The
downstream (towards the customer) bandwidth was 3.75 MHz while the
upstream (away from the customer) bandwidth was 2.5 MHz. An example
portion of the spectrum is show in Figure D-3. The BPL signal displayed
a repeating pattern of three carriers, then one carrier missing, and so
on. The BPL signal duty cycle was 100% for the downstream signal and
between 30% ‑ 100% for the upstream. The envelope of an upstream signal
is shown in Figure D-4 and it shows a duty cycle that is in the upper
end of the range.

![](media/image3.wmf){width="5.159722222222222in"
height="3.6534722222222222in"}

Figure D-3: A portion of the System #2 BPL spectrum.

![](media/image4.wmf){width="5.220138888888889in"
height="3.6909722222222223in"}Figure D-4: The envelope of an upstream
System #2 signal.

To measure System #2 emissions, the procedure involved examining the
spectrum of the BPL transmission (see Figure D-3) and identifying a
group of 3 adjacent carriers (since the measurement bandwidth was 3 kHz)
that were among the strongest and were clear of background signals. If
the signal was too weak (\<5 dB above the background noise) to clearly
see the spectrum or if background signals contaminated the BPL spectrum
at certain frequencies, a measurement was not attempted at those
frequencies. The marker in Figure D-3 shows the chosen measurement
frequency. The resolution bandwidth was then set to 3 kHz and the marker
(see Figure D-5) indicated the measured value using a peak detector.
This value was later used to calculate the Received Power at the antenna
terminals.

![](media/image5.wmf){width="5.209722222222222in"
height="4.33125in"}Figure D-5: The System #2 BPL spectrum in a 3 kHz
bandwidth.

A measurement was performed to see how the received power varied as the
receiver bandwidth was changed. This is shown in Figure D-6 for a
frequency of 22.957 MHz. The narrow dips in signal level are due to the
signal having a duty cycle of less than 100%. The upward spikes are due
to noise sources.

![](media/image6.wmf){width="4.659722222222222in"
height="3.803472222222222in"}Figure D-6: Bandwidth progression at 22.957
MHz.

[System #3]{.underline}

This BPL signal used DSSS modulation over the frequency range of about
1.8 to 21 MHz. BPL signals were transmitted on the MV and LV lines. The
BPL signal duty cycle can be up to 90% when transmissions are occurring
in both directions and about 87% for one direction. The envelope of the
BPL signal is shown in Figure D-7. Four different amplitudes from four
different transmitters are being received.

![](media/image7.wmf){width="5.209722222222222in"
height="3.716666666666667in"}Figure D-7: Four different BPL
transmitters.

In System #3, two co-frequency BPL sources were observed transmitting at
the same time, as shown in the third graticule in Figure D-8. Noise
sources can be present at levels stronger than the BPL signal as shown
in the eight and ninth graticules in Figure D-9.

![](media/image8.wmf){width="5.220138888888889in"
height="3.7194444444444446in"}Figure D-8: Two simultaneous BPL
transmissions.

![](media/image9.wmf){width="5.209722222222222in"
height="3.716666666666667in"}Figure D-9: Three BPL transmitters plus
noise.

The measurement procedure for System #3 involved examining the spectrum
of a BPL device\'s transmission and identifying a pair of frequencies
that were the strongest and were clear of background signals. For each
frequency, the signal envelope was observed for transmission bursts that
were of the correct duration and pattern. Initially, the envelope was
studied at a location where the BPL signals were received well. The
durations of many bursts were measured to determine the typical range.
This observation also yielded clearly identifiable transmission patterns
that would repeat occasionally. The results of these observations were
used to qualify the presence of BPL signals for future measurements. For
each measurement location, the strongest BPL transmission was identified
and its peak value was measured. The resolution bandwidth was then set
to 30 kHz to allow for positive identification since at 3 kHz, the
shorter BPL bursts would look like impulsive noise. The measured value
was later used to calculate the received power at the antenna terminals.

**D.3.2 Measurements of BPL Along the Energized Power Line**

Measurements of BPL emissions along the energized power line (Site A,
Figure D-10) were made using a variety of antennas. The first
measurements were taken along a fairly straight segment of power line
having both a repeater and an extractor.

![](media/image10.wmf){width="5.99375in"
height="4.022916666666666in"}Figure D-10: Measurement Site A for
measurements along the BPL energized power line.

Four measurement frequencies were chosen to represent the frequency
bands used by this system (downstream injector-to-repeater, upstream
repeater-to-injector, downstream repeater-to-extractor, and upstream
extractor-to-repeater). Three mutually orthogonal components of the
field were measured and plotted as three separate curves per graph for
the frequencies 4.303, 8.125, 22.957 and 28.298 MHz, as shown in Figures
D-11 through D-14 respectively. The measured peak power levels due to
the orthogonal components of the electric field were plotted as a
function of x, where x is the distance along the power line from the
Device C. Note that in these and all other figures depicting BPL signal
power vs. distance, lines connecting data points are connected to show
possible trends but should not be interpreted to provide expected,
interpolated values.

[Measurement Conditions]{.underline}

Measurement Location: Site A

Antenna Type: Rod

Antenna Height: 2 meters

Antenna Polarization: (X) Horizontal Parallel, (Y) Horizontal
Perpendicular,\
and (Z) Vertical

Measured Characteristic: Peak received power due to electric field

Measurement Variable: Distance along power line (x)

Comments: Measurements were made at 14 positions (x‑distances). At some\
points, the BPL signal was too weak (I/N \< 5 dB), hence,\
some curves have fewer data points.

![](media/image11.png){width="4.970138888888889in"
height="3.727777777777778in"}Figure D-11: Measured power levels along
the power line -- Site A, 4.303 MHz, rod antenna[^2]

![](media/image12.png){width="4.970138888888889in"
height="3.727777777777778in"}Figure D-12: Measured power levels along
the power line -- Site A, 8.125 MHz, rod antenna[^3]

![](media/image13.png){width="4.970138888888889in"
height="3.727777777777778in"}Figure D-13: Measured power levels along
the power line -- Site A, 22.957 MHz, rod antenna^\*^

![](media/image14.png){width="4.970138888888889in"
height="3.727777777777778in"}Figure D-14: Measured power levels along
the power line -- Site A, 28.298 MHz, rod antenna[^4]

These curves indicate that the BPL electric field (relative to noise)
along and near the line does not measurably decay with distance from the
device (Device C) and is possibly impacted by the presence of Device B.
It is interesting to note that even though the Device C is an injector
that transmitted at 8.8 MHz, the electric field actually increased with
increasing distance from the device. This is thought to be due to BPL
signal reflection by one or more impedance discontinuities (perhaps the
coupler of BPL Device B). Device B is a BPL repeater that transmitted at
28.8 MHz and 4.3 MHz. The electric field at 28.298 MHz is high closer to
Device B, but is at comparable levels at other distances away from
Device B as well.

An attempt was made to characterize the received power from the magnetic
field at this same location (Site A, repeated here as Figure D-15). The
results are illustrated in Tables D-1 thru D-4. These Tables indicate
that the magnetic field using a loop antenna at 2 meters was not
measurable along the power line at most locations.

![](media/image10.wmf){width="5.99375in"
height="4.022916666666666in"}Figure D-15: Measurement Site A for
measurements along the BPL energized power line.

[Measurement Conditions]{.underline}

Measurement Location: Site A

Antenna Type: Shielded Loop

Antenna Height: 2 meters

Antenna Polarization: (X) Horizontal Parallel, (Y) Horizontal
Perpendicular,\
and (Z) Vertical

Measured Characteristic: Peak received power due to magnetic field

Measurement Variable: Distance along power line (x)

Comments: This effort was abandoned after no signal was received for
many\
measurements.

Table D-1: Measurements along the power line -- Site A, 4.303 MHz, loop
antenna

+---------+---------+---------------+----------------+---------------+
| **X     | **Y     | **Received    | **Received     | **Received    |
| D       | D       | Power**       | Power**        | Power**       |
| istance | istance |               |                |               |
| (       | (       | **Z           | **Y            | **X           |
| feet)** | feet)** | Com           | Co             | Com           |
|         |         | ponent(dBm)** | mponent(dBm)** | ponent(dBm)** |
+---------+---------+---------------+----------------+---------------+
| 648     | 107     | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+
| 612     | 126     | *Not          | *Not measured* | *Not          |
|         |         | measured*     |                | measured*     |
+---------+---------+---------------+----------------+---------------+
| 522     | 96      | *Not          | *Not measured* | *Not          |
|         |         | measured*     |                | measured*     |
+---------+---------+---------------+----------------+---------------+
| 492     | 93      | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+
| 459     | 87      | *Not          | *Not measured* | *Not          |
|         |         | measured*     |                | measured*     |
+---------+---------+---------------+----------------+---------------+
| 417     | 123     | *Not          | *Not measured* | *Not          |
|         |         | measured*     |                | measured*     |
+---------+---------+---------------+----------------+---------------+
| 357     | 120     | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+
| 309     | 120     | *Not          | *Not measured* | *Not          |
|         |         | measured*     |                | measured*     |
+---------+---------+---------------+----------------+---------------+
| 240     | 120     | *Not          | *Not measured* | *Not          |
|         |         | measured*     |                | measured*     |
+---------+---------+---------------+----------------+---------------+
| 201     | 120     | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+
| 196     | 120     | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+
| 124     | 120     | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+
| 84      | 135     | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+
| 0       | 120     | Not           | Not measurable | Not           |
|         |         | measurable    |                | measurable    |
+---------+---------+---------------+----------------+---------------+

Table D-2: Measurements along the power line -- Site A, 8.125 MHz, loop
antenna

+---------+---------+----------------+----------------+----------------+
| **X     | **Y     | **Received     | **Received     | ## **Re        |
| D       | D       | Power**        | Power**        | ceived Power** |
| istance | istance |                |                |                |
| (       | (       | **Z            | **Y            | **X            |
| feet)** | feet)** | Co             | Co             | Co             |
|         |         | mponent(dBm)** | mponent(dBm)** | mponent(dBm)** |
+---------+---------+----------------+----------------+----------------+
| 648     | 107     | -114.94        | Not measurable | -114.94        |
+---------+---------+----------------+----------------+----------------+
| 612     | 126     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 522     | 96      | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 492     | 93      | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 459     | 87      | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 417     | 123     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 357     | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 309     | 120     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 240     | 120     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 201     | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 196     | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 124     | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 84      | 135     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 0       | 120     | -107.94        | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+

Table D-3: Measurements along the power line -- Site A, 22.957 MHz, loop
antenna

+---------+---------+----------------+----------------+----------------+
| **X     | **Y     | **Received     | **Received     | **Received     |
| D       | D       | Power**        | Power**        | Power**        |
| istance | istance |                |                |                |
| (       | (       | **Z            | **Y            | **X            |
| feet)** | feet)** | Co             | Co             | Co             |
|         |         | mponent(dBm)** | mponent(dBm)** | mponent(dBm)** |
+---------+---------+----------------+----------------+----------------+
| 648     | 107     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 612     | 126     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 522     | 96      | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 492     | 93      | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 459     | 87      | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 417     | 123     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 357     | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 309     | 120     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 240     | 120     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 201     | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 196     | 120     | Not measurable | Not measurable | -114.33        |
+---------+---------+----------------+----------------+----------------+
| 124     | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 84      | 135     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 0       | 120     | -112.48        | Not measurable | -114.48        |
+---------+---------+----------------+----------------+----------------+

Table D-4: Measurements along the power line -- Site A, 28.298 MHz, loop
antenna

+---------+---------+----------------+----------------+----------------+
| **X     | **Y     | **Received     | **Received     | **Received     |
| D       | D       | Power**        | Power**        | Power**        |
| istance | istance |                |                |                |
| (       | (       | **Z            | **Y            | **X            |
| feet)** | feet)** | Co             | Co             | Co             |
|         |         | mponent(dBm)** | mponent(dBm)** | mponent(dBm)** |
+---------+---------+----------------+----------------+----------------+
| 648     | 107     | -107.23        | -110.23        | -110.23        |
+---------+---------+----------------+----------------+----------------+
| 612     | 126     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 522     | 96      | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 492     | 93      | Not measurable | Not measurable | -112.06        |
+---------+---------+----------------+----------------+----------------+
| 459     | 87      | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 417     | 123     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 357     | 120     | Not measurable | -112.23        | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 309     | 120     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 240     | 120     | *Not measured* | *Not measured* | *Not measured* |
+---------+---------+----------------+----------------+----------------+
| 201     | 120     | -104.23        | -105.23        | -105.23        |
+---------+---------+----------------+----------------+----------------+
| 196     | 120     | -111.50        | Not measurable | -111.50        |
+---------+---------+----------------+----------------+----------------+
| 124     | 120     | Not measurable | -112.50        | -113.50        |
+---------+---------+----------------+----------------+----------------+
| 84      | 135     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+
| 0       | 120     | Not measurable | Not measurable | Not measurable |
+---------+---------+----------------+----------------+----------------+

The peak received power due to the electric field was measured with the
whip antenna along the power line (Site A, repeated here as Figure
D-16). The measured received power levels are plotted in Figure D-17
("x" referenced to Device C) and Figure D-18 ("x" referenced to Device
B). The results are similar to those obtained from the electric field
measurements previously accomplished using the rod antenna.

![](media/image10.wmf){width="5.99375in"
height="4.022916666666666in"}Figure D-16: Measurement Site A for
measurements along the BPL energized power line.

[Measurement Conditions]{.underline}

Measurement Location: Site A

Antenna Type: Whip

Antenna Height: 1.5 meters

Antenna Polarization: Vertical

Measured Characteristic: Peak received power due to electric field

Measurement Variable: Distance along power line (x) referenced to (1)
Device C, or\
(2) Device B

Comments: Note that though the measurements were initially made at a\
frequency of 7.241 MHz, the frequency was changed to 7.25 MHz\
due to background signals covering up the BPL signal.

![](media/image15.png){width="5.208333333333333in"
height="3.90625in"}Figure D-17: Measured power levels along power line
-- Site A, "x" referenced to Device C, whip antenna[^5]

![](media/image16.png){width="5.209722222222222in"
height="3.9069444444444446in"}Figure D-18: Measured power levels along
power line -- Site A, "x" referenced to Device B, whip antennaError:
Reference source not found

Measurements were taken along the BPL energized power line (Site B,
Figure D-19) using a discone antenna. Figure D-20 shows a picture of the
utility lines located at the intersection as viewed from the approximate
location of the measurement vehicle at point C. Results are shown in
Table D-5 through D-8.

![](media/image17.wmf){width="6.510416666666667in"
height="6.6875in"}Figure D-19: Measurement Site B for BPL measurements
along the power line using the discone antenna.

![](media/image18.wmf){width="4.979861111111111in" height="7.5in"}

Figure D-20: Site B power lines as viewed from the measurement vehicle
located at Point C

[Measurement Conditions]{.underline}

Measurement Location: Site B

Antenna Type: Discone (Model SAS-210/C)

Antenna Height: 2 and 10 meters

Antenna Polarization: Vertical

Measured Characteristic: 100% duty cycle power (from APDs) and pulse
power due to\
electric field

Measurement Variable: Distance along power line (x) referenced to Point
A, (y = 7.9 m)

Comments: Measurement frequencies -- 32.699 MHz and 42.465 MHz

Resolution bandwidths -- 30 kHz and 10 kHz

Pulse power measurements -- zero span, peak power detection,

> 2 ms sweep time (601 pts per sweep)
>
> Power lines approximately 8.5 meters above the ground

Table D-5: Measured 100%-duty-cycle power and pulse power, x = 4.9
meters (16 ft)

  ------- -------- --------------- --------- -------------------- --------------
          **Ant.   **Frequency**   **RBW**   **100%-duty-cycle    **Pulse
          Ht.**                              Power**              Power**

  Case 1  10 m     32.699 MHz      30 kHz    -96.3 dBm            -97.6 dBm

  Case 2  10 m     42.465 MHz      30 kHz    *Not measured*       -104.4 dBm

  Case 3  2 m      32.699 MHz      30 kHz    -101.1 dBm           -111.4 dBm

  Case 4  2 m      42.465 MHz      30 kHz    *Not measured*       -116.1 dBm

  Case 5  10 m     32.699 MHz      10 kHz    -100.7 dBm           -102.4 dBm

  Case 6  10 m     42.465 MHz      10 kHz    *Not measured*       -112.0 dBm

  Case 7  2 m      32.699 MHz      10 kHz    -111.4 dBm           -117.5 dBm

  Case 8  2 m      42.465 MHz      10 kHz    *Not measured*       -120.2 dBm
  ------- -------- --------------- --------- -------------------- --------------

Table D-6: Measured 100%-duty-cycle power and pulse power, x = 18.3
meters (60 ft)

  ------ -------- --------------- --------- -------------------- ---------------
         **Ant.   **Frequency**   **RBW**   **100%-duty-cycle    **Pulse Power**
         Ht.**                              Power**              

  Case 1 10 m     32.699 MHz      30 kHz    *Not measured*       -112.4 dBm

  Case 2 10 m     42.465 MHz      30 kHz    *Not measured*       Not measurable

  Case 5 10 m     32.699 MHz      10 kHz    -110.1 dBm           -115.2 dBm

  Case 6 10 m     42.465 MHz      10 kHz    *Not measured*       Not measurable
  ------ -------- --------------- --------- -------------------- ---------------

Table D-7: Measured 100%-duty-cycle power and pulse power, x = 23.2
meters (76 ft)

  ------- -------- --------------- --------- -------------------- ---------------
          **Ant.   **Frequency**   **RBW**   **100%-duty-cycle    **Pulse Power**
          Ht.**                              Power**              

  Case 1  10 m     32.699 MHz      30 kHz    -110.5 dBm           -108.6 dBm

  Case 2  10 m     42.465 MHz      30 kHz    *Not measured*       -107.7 dBm

  Case 3  2 m      32.699 MHz      30 kHz    Not measurable       Not measurable

  Case 4  2 m      42.465 MHz      30 kHz    Not measurable       Not measurable

  Case 5  10 m     32.699 MHz      10 kHz    -110.5 dBm           -114.9 dBm

  Case 6  10 m     42.465 MHz      10 kHz    *Not measured*       -119.3 dBm

  Case 7  2 m      32.699 MHz      10 kHz    Not measurable       Not measurable

  Case 8  2 m      42.465 MHz      10 kHz    Not measurable       Not measurable
  ------- -------- --------------- --------- -------------------- ---------------

Table D-8: Measured 100%-duty-cycle power and pulse power, x = 103.6
meters (340 ft)

  ------- -------- --------------- --------- -------------------- ---------------
          **Ant.   **Frequency**   **RBW**   **100%-duty-cycle    **Pulse Power**
          Ht.**                              Power**              

  Case 1  10 m     32.699 MHz      30 kHz    *Not measured*       -110.1 dBm

  Case 2  10 m     42.465 MHz      30 kHz    -106.9 dBm           -105.4 dBm

  Case 3  2 m      32.699 MHz      30 kHz    Not measurable       Not measurable

  Case 4  2 m      42.465 MHz      30 kHz    Not measurable       Not measurable

  Case 5  10 m     32.699 MHz      10 kHz    *Not measured*       -114.4 dBm

  Case 6  10 m     42.465 MHz      10 kHz    -111.0 dBm           -110.9 dBm

  Case 7  2 m      32.699 MHz      10 kHz    Not measurable       Not measurable

  Case 8  2 m      42.465 MHz      10 kHz    Not measurable       Not measurable
  ------- -------- --------------- --------- -------------------- ---------------

Figure D-21 summarizes the measured received power along the power lines
using data from Table D-5 through Table D-8 for a frequency of 32.699
MHz and for a vertically polarized Discone antenna at a height of 10
meters. This figure indicates that after an initial decrease of received
power, the power remains at about the same level along the power line
away from a Backhaul point.

![](media/image19.png){width="5.194444444444445in"
height="3.9027777777777777in"}

Figure D-21: Measured power levels along power line -- Site B, discone
antenna, antenna height = 10 m, frequency = 32.699 MHz, data from Table
D.3.2-5 through Table D.3.2-8[^6]

**D.3.3 Measurements of BPL Away From the Energized Power Line**

A number of measurements of BPL emissions were made with varying
distance away from the power line. In general, the measurements started
out close to a pole mounted BPL device and moved away until the signal
level was too low to make a confident measurement. For the first
measurements away from the power line, Site C's physical layout of power
lines and BPL devices is illustrated in Figure D-22 and the measured
power away from the power lines is plotted in Figure D-23. With a loop
antenna directly under the power line at a height of 2 meters, a small
signal power was measured on all four frequencies (4.419 MHz, 8.777 MHz,
23.836 MHz and 28.777 MHz). At a distance of 148 feet from the power
line, the signal was received only at 28.777 MHz as shown in Figure
D-23.

![](media/image20.wmf){width="5.323611111111111in"
height="3.5722222222222224in"}Figure D-22: Measurement Site C for BPL
measurements away from the power line at Device B

[Measurement Conditions]{.underline}

Measurement Location: Site C

Antenna Type: Shielded Loop

Antenna Height: 2 meters

Antenna Polarization: Horizontal Parallel

Measured Characteristic: Peak received power due to magnetic field

Measurement Variable: Distance away from power line (x)

Comments: Device A is an Extractor transmitting an upstream signal at
23.8\
MHz. Device B is a repeater transmitting on 28.8 MHz\
downstream and 4.4 MHz upstream. Device C is an injector\
transmitting on 8.8 MHz downstream. When the antenna was\
moved 45.1 meters (148 ft) away from the power line the signal\
was not received on 3 of the 4 frequencies.

![](media/image21.png){width="6.009722222222222in"
height="4.510416666666667in"}Figure D-23: Measured power levels away
from the power line, Site C, loop antenna[^7]

The peak received power due to the electric field was measured with the
whip antenna away from the power line (Site C, repeated here as Figure
D-24) at 4.255 MHz, 7.304 MHz and 28.777 MHz with the results shown in
Figure D-25. The results indicate that there was a decrease in received
power with increase in distance from the BPL device and power line, but
the decrease was not monotonic at 28.777 MHz. The received power and the
manner in which it decreased with increasing distance varied
substantially at different frequencies.

![](media/image20.wmf){width="5.323611111111111in"
height="3.5722222222222224in"}Figure D-24: Measurement Site C for BPL
measurements away from the power line at Device B

[Measurement Conditions]{.underline}

Measurement Location: Site C

Antenna Type: Whip

Antenna Height: 1.5 meters

Antenna Polarization: Vertical

Measured Characteristic: Peak received power due to electric field

Measurement Variable: Distance away from power line (x)

Comments: At 7.304 MHz, the measurement was terminated when background\
signals appeared and covered up the BPL signal. The frequency\
change to 4.241 MHz was due to background signals covering up\
the BPL signal.

![](media/image22.png){width="6.009722222222222in"
height="4.51875in"}**Figure D-25: Measured power levels away from power
line at Device B -- Site C, whip antenna**[^8]

The peak received power due to the electric field was measured with the
whip antenna on a different path (measurement trend line) as a function
of distance from the power line as shown in Figure D-26. The results,
plotted in Figure D-27, show that even though the received power
generally decreased with distance from Device C, the peak power level at
28.809 MHz exhibited significant oscillations as a function of
increasing distance.

![](media/image23.wmf){width="5.315972222222222in"
height="3.576388888888889in"}Figure D-26: Measurement Site C for BPL
measurements away from the power line at Device C

[Measurement Conditions]{.underline}

Measurement Location: Site C

Antenna Type: Whip

Antenna Height: 1.5 meters

Antenna Polarization: Vertical

Measured Characteristic: Peak received power due to electric field

Measurement Variable: Distance away from power line (x)

Comments: At 7.241 MHz, the measurement was terminated when background\
signals appeared and covered up the BPL signal.

![](media/image24.png){width="6.009722222222222in"
height="4.506944444444445in"}Figure D-27: Measured power levels away
from power line at Device B -- Site C, whip antenna[^9]

Another set of measurements were made of the peak received power due to
vertical electric field while moving the whip antenna away from the
power line as shown in Figure D-28 (Site D). The received power has been
plotted versus distance from the power lines in Figure D-29. In Figure
D-29, the signal decreases to an immeasurable level within 600 ft.

![](media/image25.wmf){width="4.649305555555555in"
height="4.545138888888889in"}Figure D-28: Measurement Site D for BPL
measurements away from power line at a pole mounted repeater

[Measurement Conditions]{.underline}

Measurement Location: Site D

Antenna Type: Whip

Antenna Height: 1.5 meters

Antenna Polarization: Vertical

Measured Characteristic: Peak received power due to electric field

Measurement Variable: Distance away from power line (x)

Comments: None

![](media/image26.png){width="6.009722222222222in"
height="4.506944444444445in"}Figure D-29: Measured power levels away
from power line -- Site D, whip antenna[^10]

The next measurements were made away from the power lines at Site E. The
physical layout (Figure D-30) shows several repeaters and one
concentrator (injector) and a network of MV lines all transmitting at
various times over the same frequency range. In Figure D-31, the
received power at 8.1 MHz and 14.8 MHz are plotted versus distance from
the power lines, out to a distance exceeding 1500 ft, where the BPL
signal diminished to within 5 dB of the noise floor.

![](media/image27.wmf){width="5.392361111111111in"
height="3.9131944444444446in"}Figure D-30: Measurement Site E for BPL
measurements away from power line at a repeater

[Measurement Conditions]{.underline}

Measurement Location: Site E

Antenna Type: Whip

Antenna Height: 1.5 meters

Antenna Polarization: Vertical

Measured Characteristic: Peak received power due to electric field

Measurement Variable: Distance away from power line (x)

Comments: None

![](media/image28.png){width="6.009722222222222in"
height="4.506944444444445in"}Figure D-31: Measured power levels away
from power line -- Site E, whip antenna[^11]

The peak received power was measured using both whip and loop antennas
at heights of 1.5 and 2 meters, respectively, near a transformer with
underground power lines (Site F) carrying BPL signals. The measurements
show that at 6.4 meters (21 ft) from the transformer, the BPL signal
power was measurable at one of the three BPL frequencies as shown in
Table D-9. At 29.3 meters (96 ft) from the transformer, no signal could
be detected.

[Measurement Conditions]{.underline}

Measurement Location: Site F

Antenna Type: Whip, Shielded Loop

Antenna Height: 1.5 meters (whip) and 2 meters (loop)

Antenna Polarization: Whip - Vertical, Loop - Vertical Parallel,
Vertical Perpendicular and Horizontal

Measured Characteristic: Peak received power due to electric and
magnetic fields

Measurement Variable: Distance away from power line (x)

Comments: None

Table D-9: Measure power levels away from power line -- Site F, whip &
loop antennas

+------------+----------+---------+----------+-----------+-----------+
| **M        | **Fre    | *       | **Loop** | **Loop**  | **Loop**  |
| easurement | quency** | *Whip** |          |           |           |
| Distance** |          |         | **(V     | **(       | **(Hori   |
|            | *        | **(Vert | ertical, | Vertical, | zontal)** |
|            | *(MHz)** | ical)** | parallel | perp      |           |
|            |          |         | to the   | endicular |           |
|            |          |         | power    | to the    |           |
|            |          |         | line)**  | power     |           |
|            |          |         |          | line)**   |           |
+------------+----------+---------+----------+-----------+-----------+
| 6.4 m (21  | 3.99     | Not     | Not      | Not       | Not       |
| ft)        |          | mea     | me       | m         | m         |
|            |          | surable | asurable | easurable | easurable |
+------------+----------+---------+----------+-----------+-----------+
| 6.4 m (21  | 7.502    | Not     | Not      | Not       | Not       |
| ft)        |          | mea     | me       | m         | m         |
|            |          | surable | asurable | easurable | easurable |
+------------+----------+---------+----------+-----------+-----------+
| 6.4 m (21  | 15.285   | -80 dBm | -114 dBm | Not       | ‑114 dBm  |
| ft)        |          |         |          | m         |           |
|            |          |         |          | easurable |           |
+------------+----------+---------+----------+-----------+-----------+
| 29.3 m (96 | 3.99     | Not     | Not      | Not       | Not       |
| ft)        |          | mea     | me       | m         | m         |
|            |          | surable | asurable | easurable | easurable |
+------------+----------+---------+----------+-----------+-----------+
| 29.3 m (96 | 7.502    | Not     | Not      | Not       | Not       |
| ft)        |          | mea     | me       | m         | m         |
|            |          | surable | asurable | easurable | easurable |
+------------+----------+---------+----------+-----------+-----------+
| 29.3 m (96 | 15.285   | Not     | Not      | Not       | Not       |
| ft)        |          | mea     | me       | m         | m         |
|            |          | surable | asurable | easurable | easurable |
+------------+----------+---------+----------+-----------+-----------+

Measurements were performed using a discone antenna with the power line
configuration as shown in Figure D-32 for Site G. Manual pulse power
measurements are plotted for three frequencies, 35.04992 MHz, 39.92954
MHz and 45.40195 MHz, as shown in Figure D-33. Also included are
theoretical plots for loss proportional to 1/*R*, 1/*R*^2^, and
1/*R*^4^, where *"R"* is distance from the power line (*i.e.*, "R" is
depicted as the parameter "*x"* in Figure D-32). The results indicate
that the received power decreases as distance from the power line
increases at a rate lower than would be predicted by 1/R^2^ (space wave
loss).

![](media/image29.wmf){width="3.8097222222222222in"
height="4.103472222222222in"}Figure D-32: Measurement Site G for BPL
measurements away from power line using the discone antenna

[Measurement Conditions]{.underline}

Measurement Location: Site G

Antenna Type: Discone (Model SAS-210/C)

Antenna Height: 3.4 meters (11.2 ft)

Antenna Polarization: Vertical

Measured Characteristic: Peak received power due to electric field

Measurement Variable: Distance away from power line (x)

Comments: Measurement frequencies -- 35.04492 MHz, 39.92954 MHz, and\
45.40195 MHz

Resolution bandwidths -- 200 kHz

Pulse power measurements -- zero span, peak power detection,

> 2 ms sweep time (601 pts per sweep)
>
> Power lines approximately 8.5 meters above the ground

![](media/image30.png){width="6.0in" height="4.5in"}**Figure D-33:
Received pulse power measured away from power line -- Site G, discone
antenna**[^12]

Manual pulse power levels were measured at 32.699 MHz and 42.465 MHz
with the same discone antenna at points B and C as shown in Figure D-34.
Both points B and C are at
![](media/image17.wmf){width="4.779861111111111in"
height="4.909722222222222in"}about the same distance from the power
line; however, the measured pulse power at point C is consistently
higher than at point B as shown in Tables D-10 and D-11.

Figure D-34: Measurement Site B for BPL measurements away from power
line

[Measurement Conditions]{.underline}

Measurement Location: Site B

Antenna Type: Discone (Model SAS-210/C)

Antenna Height: 10 meters

Antenna Polarization: Vertical

Measured Characteristic: Pulse power measurements at two different
radials; 100% duty\
cycle power determined from APDs measured at one of the radials

Measurement Variable: Point B and Point C, radials away from the utility
pole at the end of a BPL carrying segment of MV power line.

Comments: Measurement frequencies -- 32.699 MHz and 42.465 MHz

Resolution bandwidths -- 10 kHz and 30 kHz

Pulse power measurements -- zero span, peak power detection,

> 2 ms sweep time (601 pts per sweep)

Table D-10: Measured pulse power -- Site B, Point B, discone antenna,
radial 20.7 meters from utility pole.

+--------+--------------+----------------+----------------------------+
|        | *            | # **RBW**      | # **Pulse Power**          |
|        | *Frequency** |                |                            |
+--------+--------------+----------------+----------------------------+
| Case 1 | 32.699 MHz   | 30 kHz         | Not measurable             |
+--------+--------------+----------------+----------------------------+
| Case 2 | 42.465 MHz   | 30 kHz         | -112.2 dBm                 |
+--------+--------------+----------------+----------------------------+
| Case 3 | 32.699 MHz   | 10 kHz         | Not measurable             |
+--------+--------------+----------------+----------------------------+
| Case 4 | 42.465 MHz   | 10 kHz         | Not measurable             |
+--------+--------------+----------------+----------------------------+

Table D-11: Measured 100%-duty-cycle power and pulse power -- Site B,
Point C, discone antenna, radial 20.4 meters from utility pole.

  ------- --------------- ------------- ------------------- --------------------
          **Frequency**   **RBW**       **100%-duty-cycle   **Pulse Power**
                                        Power**             

  Case 1  32.699 MHz      30 kHz        -104.1 dBm          -106.4 dBm

  Case 2  42.465 MHz      30 kHz        *Not measured*      -110.2 dBm

  Case 3  32.699 MHz      10 kHz        -109.7 dBm          -109.7 dBm

  Case 4  42.465 MHz      10 kHz        *Not measured*      Not measurable
  ------- --------------- ------------- ------------------- --------------------

**D.3.4 Measurements of BPL Using Various Detectors**

> Measurements were made using three different spectrum analyzer
> detectors (peak, average and quasi‑peak.) at Site A, as shown in
> Figure D-35. Table D-12 and D-13 show the detector levels for the two
> measurement frequencies. The data shown in these tables indicate that
> the measured quasi-peak power levels for this BPL signal are 0 to 5 dB
> greater than the average power levels.

![](media/image10.wmf){width="6.509722222222222in"
height="4.3694444444444445in"}Figure D-35: Measurement Site A for BPL
measurements using various detectors

[Measurement Conditions]{.underline}

Measurement Location: Site A

Antenna Type: Whip

Antenna Height: 1.5 meters

Antenna Polarization: Vertical

Measured Characteristic: Peak, average, and quasi-peak power due to
electric field

Measurement Variable: Distance away from power line (x, y)

Comments: Resolution bandwidths -- 9.1 kHz (peak & average),\
9 kHz quasi-peak

> Signal‑to‑noise ratio (SNR) at 22.957 MHz was 8 dB
>
> SNR at 28.298 MHz was 38 dB.

Table D-12: Measured peak, average and quasi-peak levels, x = 150 m, y =
28.3 m

  -------------------- ---------------- ---------------- ----------------
  **Detector**         **Peak**         **Average**      **Quasi-Peak**

  Value at f = 22.957  -74 dBm          -81 dBm          -76 dBm
  MHz                                                    
  -------------------- ---------------- ---------------- ----------------

Table D-13: Measured peak, average and quasi-peak levels, x = 58.2 m, y
= 39.3 m

  -------------------- ---------------- ---------------- ----------------
  **Detector**         **Peak**         **Average**      **Quasi-Peak**

  Value at f = 28.298  -60 dBm          -65 dBm          -65 dBm
  MHz                                                    
  -------------------- ---------------- ---------------- ----------------

The measurements using the various detectors were made in a residential
neighborhood environment. There were noise sources present, some of them
appear impulsive on a spectrum analyzer and some appear bursty. Figure
D-36 shows both kinds of noise sources at levels higher than the BPL
signal. While it is possible to read the BPL level in between these
noise sources with a peak and average (due to the 100% BPL duty cycle
and if the symbol period is short enough) detector, the quasi‑peak
detector, with its longer time constant, will include the noise power in
its measurement. When the BPL signal has a duty cycle less than 100%
with a period greater than the period of the noise sources, the average
detector will include the noise power in its measurement. An example of
this signal is shown in Figure D-37. The period of the noise sources is
much shorter than the period of the BPL signal. The off periods are
large enough to cause the quasi‑peak detector level to decay, Figure
D-38, so to obtain a single value the operator chose a value when the
BPL signal was on and ignored the noise induced spike near the center of
the trace.

![](media/image31.wmf){width="4.9in" height="3.783333333333333in"}Figure
D-36: BPL signal at 28.298 MHz.

![](media/image32.wmf){width="4.740277777777778in"
height="3.79375in"}Figure D-37: BPL signal at 22.957 MHz.

![](media/image33.wmf){width="4.879861111111111in"
height="3.9375in"}Figure D-38: BPL signal at 22.957 MHz.

Another measurement was made to compare detectors at a different
location at Site A and on a different day. The results are in Table
D-14.

[Measurement Conditions]{.underline}

Measurement Location: Site A

Antenna Type: Whip

Antenna Height: 1.5 meters

Antenna Polarization: Vertical

Measured Characteristic: Peak, average, and quasi-peak power due to
electric field

Measurement Variable: Distance away from power line (x, y)

Comments: Resolution bandwidths -- 3 kHz , corresponding to a typical
land‑mobile signal bandwidth in the HF spectrum

Table D-14: Measured detector levels, x -- directly in front of Device
B, y = 12.2 m

  ---------------- ------------------ ------------------ ------------------
                   **Frequency**                         

  Detector         4.255 MHz          7.304 MHz          28.777 MHz

  Peak             ‑72 dBm            ‑60.4 dBm          -54.8 dBm

  Average          ‑74.8 dBm          ‑63.5 dBm          ‑56.6 dBm

  Quasi‑Peak       ‑71.3 dBm          ‑59.3 dBm          ‑55.3 dBm
  ---------------- ------------------ ------------------ ------------------

**D.3.5 Measurements of BPL Varying Antenna Height**

Measurements were performed using two different antenna heights at Site
B, Figure D-39. Results are shown in Table D-15. The results show that
in general, the measured power levels were higher at the greater antenna
height. For example, the 100% duty cycle power measured at a frequency
of 32.699 MHz and at a 10 meter antenna height was 4.8 to 10.7 dB
greater than at 2 meters. The pulse power at a 10 meter antenna height
for this same frequency was 8.2 to 15.1 dB higher than at 2 meters.

![](media/image17.wmf){width="6.1in"
height="6.2659722222222225in"}Figure D-39: Measurement Site B for BPL
measurements with varying antenna height

[Measurement Conditions]{.underline}

Measurement Location: Site B

Antenna Type: Discone (Model SAS-210/C)

Antenna Height: 2 and 10 meters

Antenna Polarization: Vertical

Measured Characteristic: 100% duty cycle power (from APDs) and pulse
power due to\
electric field

Measurement Variable: Distance along power line (x = 4.9 m) referenced
to Point A, (y = 7.9 m)

Comments: Measurement frequencies -- 32.699 MHz and 42.465 MHz

Resolution bandwidths -- 30 kHz and 10 kHz

Pulse power measurements -- zero span, peak power detection,

> 2 ms sweep time (601 pts per sweep)
>
> Power lines approximately 8.5 meters above the ground

Table D-15: Measured 100%-duty-cycle power and pulse power -- Site B,
discone antenna, two antenna heights

  ------- -------- --------------- --------- -------------------- ---------------
          **Ant.   **Frequency**   **RBW**   **100%-duty-cycle    **Pulse Power**
          Ht.**                              Power**              

  Case 1  10 m     32.699 MHz      30 kHz    -96.3 dBm            -97.6 dBm

  Case 2  10 m     42.465 MHz      30 kHz    *Not measured*       -104.4 dBm

  Case 3  2 m      32.699 MHz      30 kHz    -101.1 dBm           -111.4 dBm

  Case 4  2 m      42.465 MHz      30 kHz    *Not measured*       -116.1 dBm

  Case 5  10 m     32.699 MHz      10 kHz    -100.7 dBm           -102.4 dBm

  Case 6  10 m     42.465 MHz      10 kHz    *Not measured*       -112.0 dBm

  Case 7  2 m      32.699 MHz      10 kHz    -111.4 dBm           -117.5 dBm

  Case 8  2 m      42.465 MHz      10 kHz    *Not measured*       -120.2 dBm
  ------- -------- --------------- --------- -------------------- ---------------

Measurements were conducted at Site H as shown in Figure D-40. Figure
D-41 shows a picture of the utility lines located immediately in front
of the house as viewed from across the street parallel to the
approximate location of the measurement vehicle.

![](media/image34.wmf){width="5.997222222222222in" height="3.5in"}Figure
D-40: Measurement Site H for BPL measurements with varying antenna
height

[Measurement Conditions]{.underline}

Measurement Location: Site H

Antenna Type: Shielded Loop

Antenna Height: 2 meters and 10 meters

Antenna Polarization: Vertical, plane of antenna perpendicular to power
line

Measured Characteristic: Pulse power measurements and 100% duty cycle
power (from APDs) of the magnetic field

Measurement Variable: Distance away from low voltage power line (x = 8.7
meters)

Comments: Measurement frequencies -- 5.00 MHz, 6.43 MHz, 10.74 MHz\
and 18.38 MHz

Resolution bandwidths -- 3 kHz and 10 kHz

Pulse power measurements -- zero span, peak power detection,

> 5 ms sweep time (601 pts per sweep)
>
> Power line height ranging approximately 3 -- 4.3 meters

The pulse-power and the 100%-duty-cycle power (both referenced to the
antenna output) are shown for each case in Table D-16. The results shown
indicate that measured power at a 10 meter height was always larger than
the power measured at 2 meter height (by 3-10 dBm).

![](media/image35.wmf){width="4.979861111111111in"
height="7.500694444444444in"}

Figure D-41: Measurement Site H utility lines located immediately in
front of house as viewed from\
across the street parallel to the approximate location of the
measurement vehicle.

Table D-16: Measured 100%-duty-cycle power and pulse power -- Site H,
loop antenna, two antenna heights

  -------- -------- --------------- ------------- ------------------- --------------
           **Ant.   **Frequency**   **RBW**       **100%-duty-cycle   **Pulse
           Ht.**                                  Power**             Power**

  Case 1   10 m     5.00 MHz        10 kHz        Not measurable      Not measurable

  Case 2   10 m     5.00 MHz        3 kHz         Not measurable      Not measurable

  Case 3   10 m     6.43 MHz        10 kHz        -106.4 dBm          -112.3 dBm

  Case 4   10 m     6.43 MHz        3 kHz         -108.7 dBm          -114.0 dBm

  Case 5   10 m     10.74 MHz       10 kHz        *Not measured*      -110.3 dBm

  Case 6   10 m     10.74 MHz       3 kHz         -114.8 dBm          Not measurable

  Case 7   10 m     18.38 MHz       10 kHz        *Not measured*      -101.4 dBm

  Case 8   10 m     18.38 MHz       3 kHz         -106.6 dBm          -110.8 dBm

  Case 9   2 m      5.00 MHz        10 kHz        Not measurable      Not measurable

  Case 10  2 m      5.00 MHz        3 kHz         Not measurable      Not measurable

  Case 11  2 m      6.43 MHz        10 kHz        -109.1 dBm          Not measurable

  Case 12  2 m      6.43 MHz        3 kHz         -113.3 dBm          -112.6 dBm

  Case 13  2 m      10.74 MHz       10 kHz        Not measurable      Not measurable

  Case 14  2 m      10.74 MHz       3 kHz         Not measurable      Not measurable

  Case 15  2 m      18.38 MHz       10 kHz        -111.2 dBm          -113.3 dBm

  Case 16  2 m      18.38 MHz       3 kHz         -115.3 dBm          -117.3 dBm
  -------- -------- --------------- ------------- ------------------- --------------

**D.3.6 Measurements of BPL APDs**

APD measurements of the BPL signal were taken at Site I, as shown in
Figure D-42. Results of these measurements, shown as 100% duty cycle
power and / or pulse power levels are shown in Table D-17. This table
shows that 100% duty cycle power is higher for higher resolution
bandwidth at a given frequency and the power levels are proportional to
bandwidth (confirming that 100% equivalent power was accurately
estimated from APDs).

![](media/image36.wmf){width="4.222222222222222in"
height="4.555555555555555in"}Figure D-42: Measurement Site I for BPL APD
measurements

[Measurement Conditions]{.underline}

Measurement Location: Site I

Antenna Type: Discone (Model SAS-210/C)

Antenna Height: 10 meters

Antenna Polarization: Vertical

Measured Characteristic: 100% duty cycle power (from APDs) of the
electric field

Measurement Variable: Distance away from low voltage power line (x =
11.6 meters)

Comments: Measurement frequencies -- 32.699 MHz and 42.465 MHz

Resolution bandwidths -- 10 kHz, 30 kHz and 200 kHz

Table D-17: Measured 100%-duty-cycle power from APDs -- Site I, discone
antenna, x = 11.6 meters.

  --------- ----------------- ----------------- --------------------------
            **Frequency**     **RBW**           **100%-duty-cycle Power**

  Case 1    32.699 MHz        200 kHz           -93.6 dBm

  Case 2    32.699 MHz        30 kHz            -98.9 dBm

  Case 3    32.699 MHz        10 kHz            -103.5 dBm

  Case 4    42.465 MHz        200 kHz           -95.3 dBm

  Case 5    42.465 MHz        30 kHz            -101.8 dBm

  Case 6    42.465 MHz        10 kHz            -107.4 dBm
  --------- ----------------- ----------------- --------------------------

Another set of pulse-power measurements and APDs were performed at Site
I at 32.699 MHz with two different resolution bandwidths (30 kHz, and 10
kHz) and three different antenna orientations. These results are shown
in Table D-18. Figure D-43 shows APD plots for cases 7, 8, and 9 as
described in the Table D-18. Both Table D-18 and Figure D-43 indicate
that the measured power for all four cases is at similar levels for the
same location.

.

[Measurement Conditions]{.underline}

Measurement Location: Site I

Antenna Type: Discone (Model SAS-210/C)

Antenna Height: 2 meters

Antenna Polarization: Varies, see Table D.3.6-2

Measured Characteristic: Pulse power measurements and 100% duty cycle
power (from APDs) of the electric field

Measurement Variable: Distance away from low voltage power line (x) and
backhaul pt (y)

Comments: Measurement frequency -- 32.699 MHz

Resolution bandwidths -- 10 kHz and 30 kHz

Pulse power measurements -- zero span, peak power detection,

> 2 ms sweep time (601 pts per sweep)

Table D-18: Measured 100%-duty-cycle power from APDs and\
Pulse Power -- Site I, discone antenna, various x-y distances

+------+----------+----------------+-------+------------+------------+
|      | **       | **Antenna      | **    | **100%-    | **Pulse    |
|      | Direct** | orientation**  | RBW** | duty-cycle | power**    |
|      |          |                |       | Power**    |            |
|      | **Dis    |                |       |            |            |
|      | tances** |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
| Case | x = 11.7 | Vert.          | 30    | -107.5 dBm | -114.6 dBm |
| 1    | m        | Polarization   | kHz   |            |            |
|      |          |                |       |            |            |
|      | y = 15.2 |                |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | -112.6 dBm | -115.6 dBm |
|      |          |                | kHz   |            |            |
+------+----------+----------------+-------+------------+------------+
| Case | x = 17.1 | ## Vert        | 30    | -107.4 dBm | -112.3 dBm |
| 2    | m        | . Polarization | kHz   |            |            |
|      |          |                |       |            |            |
|      | y = 19.5 |                |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | -112.2 dBm | -117.2 dBm |
|      |          |                | kHz   |            |            |
+------+----------+----------------+-------+------------+------------+
| Case | x = 23.0 | Vert.          | 30    | Not        | Not        |
| 3    | m        | Polarization   | kHz   | measurable | measurable |
|      |          |                |       |            |            |
|      | y = 25.0 |                |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | Not        | Not        |
|      |          |                | kHz   | measurable | measurable |
+------+----------+----------------+-------+------------+------------+
| Case | x = 23.0 | Horz.          | 30    | Not        | Not        |
| 4    | m        | Polarization   | kHz   | measurable | measurable |
|      |          | parallel to    |       |            |            |
|      | y = 25.0 | lines          |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | Not        | Not        |
|      |          |                | kHz   | measurable | measurable |
+------+----------+----------------+-------+------------+------------+
| Case | x = 17.1 | Horz.          | 30    | Not        | Not        |
| 5    | m        | Polarization   | kHz   | measurable | measurable |
|      |          | parallel to    |       |            |            |
|      | y = 19.5 | lines          |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | Not        | Not        |
|      |          |                | kHz   | measurable | measurable |
+------+----------+----------------+-------+------------+------------+
| Case | x = 17.1 | Horz.          | 30    | Not        | Not        |
| 6    | m        | Polarization   | kHz   | measurable | measurable |
|      |          | perpendicular  |       |            |            |
|      | y = 19.5 | to lines       |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | Not        | Not        |
|      |          |                | kHz   | measurable | measurable |
+------+----------+----------------+-------+------------+------------+
| Case | x = 11.7 | Horz.          | 30    | -107.9 dBm | -110.1 dBm |
| 7    | m        | Polarization   | kHz   |            |            |
|      |          | perpendicular  |       |            |            |
|      | y = 15.2 | to lines       |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | -113.1 dBm | -115.8 dBm |
|      |          |                | kHz   |            |            |
+------+----------+----------------+-------+------------+------------+
| Case | x = 11.7 | Horz.          | 30    | -106.2 dBm | -110.3 dBm |
| 8    | m        | Polarization   | kHz   |            |            |
|      |          | parallel to    |       |            |            |
|      | y = 15.2 | lines          |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | -113.3 dBm | -118.1 dBm |
|      |          |                | kHz   |            |            |
+------+----------+----------------+-------+------------+------------+
| Case | x = 11.7 | Horz.          | 30    | -107.8 dBm | -111.1 dBm |
| 9    | m        | Polarization   | kHz   |            |            |
|      |          | pointed to     |       |            |            |
|      | y = 15.2 | pole           |       |            |            |
|      | m        |                |       |            |            |
+------+----------+----------------+-------+------------+------------+
|      |          |                | 10    | -109.0 dBm | -116.8 dBm |
|      |          |                | kHz   |            |            |
+------+----------+----------------+-------+------------+------------+

The 100% duty-cycle power and manual pulse power levels were observed to
be nearly the same for measurements performed at the same location with
the antenna pointed in different directions (Case 7 -- Case 9).

![](media/image37.png){width="6.263194444444444in"
height="4.697222222222222in"}

Figure D-43: APD measurements in a 30 kHz RBW for three different
antenna\
orientations -- Site I, located with a 11.7 m direct distance from power
lines

**D.4 BACKGROUND ON AMPLITUDE PROBABILITY\
DISTRIBUTIONS**

Because of the random nature of the system noise, background noise, and
the BPL signal itself, signal power data were, at times, collected and
analyzed statistically using amplitude probability distributions
(APDs).[^13]

The reason for using APDs was to differentiate the BPL signal from the
background (and system) noise and to extract mean power. While the APD
can be used to characterize the background noise, doing so requires a
sufficiently large ensemble and adequate sensitivity. It was not the
original intention to use these measurements for the purpose of
characterizing the background noise; therefore, the extent of sampling
and the system configuration limit the use of these APDs for that
purpose.

Data for these measurements were acquired by repeatedly collecting power
traces from a spectrum analyzer and placing the power values in
corresponding 0.1-dB bins of a histogram (later to be used for creating
APDs). The spectrum analyzer was set in sample detection mode with a
zero span and centered on specified frequencies of interest. So as to
assure uncorrelated sampling, the trace sweep-time was set so that
adjacent data points were no closer in time than 2/RBW, where RBW is the
resolution bandwidth. To provide sufficient probability resolution, a
minimum of 500,000 samples were collected for each APD - enough to give
a probability of a single occurrence equal to 0.0002% .

By repeatedly collecting power data when the transmission lines are
loaded with BPL and when the BPL is turned off, it is possible to
identify the power contribution by BPL, assuming that the background
noise does not change significantly. For example, Figure D-44 shows the
APDs for the two scenarios - BPL on and BPL off. The "system noise" plot
is emulated by calculating the curve from the system noise figure.
Though the data from the two scenarios were not collected
simultaneously, the characteristics of the noise environment, in this
case, were changed only by inclusion or exclusion of the BPL signal. The
features noted between points B and D are due predominantly to the BPL
signal, whereas the features between points A and B for the "BPL-loaded"
case and points A and C for the "BPL-off" case are due predominantly to
extraneous environmental impulsive noise. The linear regions of the
curves are due to system noise.

By taking multiple APDs of these two scenarios, it is possible to
identify APD features that are characteristic of the BPL signal. For
instance, after examining multiple APDs, it was possible to conclude
that, for this example data, the BPL signal is present approximately 10%
of the time when loaded. Figure D-45 shows data collected in a slightly
different location within the site. However, in this example, changes in
the noise environment between "loaded" and "off" cases are due not only
to the BPL being turned off, but also due to some additional impulsive
noise as noted in the region between points B and D of the "BPL-off"
plot. Despite this added complexity, it is still possible to identify
the power contribution by BPL because the region between points C and E
on the "BPL-loaded" plot has the characteristic feature of 10% presence,
and this feature of the curve is absent for the "BPL-off" case.

![](media/image38.png){width="5.029861111111111in"
height="3.783333333333333in"}Figure D-44: Example APD plots for two
different measurement scenarios - BPL loaded and BPL off.

![](media/image39.png){width="5.041666666666667in"
height="3.8020833333333335in"}Figure D-45: Example APD plots for two
different measurement scenarios - BPL loaded and BPL off.

For each of the APD plots, the powers on the ordinate are referenced to
the output of the antenna terminals. Mean powers are calculated from the
associated histograms by:

![](media/image40.png){width="1.0in" height="0.6111111111111112in"}

where *x*~i~ is power in the i^th^ bin, *n*~i~ is the number of samples
in the i^th^ bin, and *N* is the total number of samples. In cases where
the system noise or environmental noise may contribute significantly to
the overall signal power, the mean signal power of the BPL is determined
by subtracting the mean system noise power and/or environmental noise
from the overall mean signal power. In some cases, the background noise
is low enough in power or infrequent enough (for impulsive noise) that
their contribution to the overall power can be disregarded.

For data shown in Figure D.46, the BPL signal is pulse-like in nature,
and between the pulses, the signal power is dominated by the system (and
environmental) noise. The calculated mean 100%-duty-cycle power (*i.e.*,
the power when the pulses are present 100% of the time) is determined
from the measured percentage of time the BPL pulses are present using
the following equation:

![](media/image41.png){width="2.0in" height="0.7083333333333334in"}where
*M*~p~ is the mean 100%-duty-cycle power in decibels, *M*~s~ is the mean
measured signal power in decibels, and *P* is the percentage of time the
measured BPL pulses are present. *M*~s~ is determined by subtracting
mean power of the system noise from the mean power for the BPL-on data.
Though there appears to be some impulsive environmental noise (far left
side of the plot) contributing to the mean power of the BPL-on case, the
probability (in combination with the magnitude) of this impulsive
environmental noise is low enough that it contributes little to the
overall mean power. To estimate *P*, it is assumed that the point at
which the curve deviates from the system noise curve by 1.8 dB
represents the point at which BPL pulses are starting to significantly
contribute additional power above that of the system noise, and
therefore, this represents the percent of the time for which the BPL
pulses are present.[^14] For Figure D-46, this point occurs at 11%, and
therefore, because the mean signal power is calculated to be\
-111.7 dBm, the mean pulse power is -103.3 dBm. It should be emphasized,
however, that *P* and *M*~s~ are estimates and dependent upon an
understanding of the background noise. Because the system noise power is
Rayleigh distributed, the mean power occurs at the 37^th^ percentile
(true for any Rayleigh distributed power that is predominantly system
noise); therefore for Figure D-46, the BPL pulse power is 18 dB above
the mean system noise.

![](media/image42.png){width="5.2in" height="3.911111111111111in"}

Figure D-46: Mean power for pulse-like BPL signal, dominated by system
noise between pulses.

This measurement technique was verified by simulating a pulsed signal of
known power and performing the same measurement and processing
procedure. The simulated signal was centered at 30 MHz with a 10% duty
cycle. Figures D-47 and D-48 shows the signal as measured on a spectrum
analyzer with a span of zero. Figure D-47 shows the signal with a peak
pulse power well above the system noise. Figure D-48 shows the signal
with a peak pulse power approximately 6 dB above the system noise (--105
dBm at the input to the preselector). Because the peak pulse power could
not be readily measured for the case where the power is less than 10 dB
above the system noise, the peak pulse power was measured when it was
well above the system noise and then attenuated prior to the
preselector. APDs were performed for two different peak pulse power at
the input to the preselector: -83 dBm and --105 dBm. The data were
acquired and processed for mean signal power, mean 100%-duty-cycle
power, and the measured duty cycle. Results are shown in Figures D-49
and D-50. In both cases, the mean 100%-duty-cycle power coincides well
with the actual measured peak pulse power.

![](media/image43.wmf){width="5.990277777777778in"
height="4.490277777777778in"}

Figure D-47: Simulated signal with a peak pulse power well above the
system noise.

![](media/image44.wmf){width="5.990277777777778in" height="4.5in"}

Figure D-48: Simulated signal with a peak pulse power 6 dB above the
system noise.

![](media/image45.png){width="5.044444444444444in"
height="3.7777777777777777in"}

Figure D-49: APD of simulated signal with a peak pulse power of -83 dBm
at the input to the preselector.

![](media/image46.png){width="5.044444444444444in"
height="3.7777777777777777in"}

Figure D-50: APD of simulated signal with a peak pulse power of -105 dBm
at the input to the preselector.

Figure D-51 shows APDs for data acquired for two conditions: when the
BPL was loaded and when the BPL was turned off. In this case, there
appears to be some impulsive noise that is present during both
acquisitions. And though the contribution to the mean power by this
impulsive noise is probably insignificant, it is possible to remove the
effects of both environmental impulsive noise and the system noise by
finding the difference in mean powers between the two data sets.
Therefore, the mean measured signal power (*M*~s~), in this case, is
determined by subtracting the mean power for the BPL-off case from the
mean power for the BPL-on case. The 100%-duty-cycle power is determined
as described in the preceding paragraph.

![](media/image47.png)Figure D-51: Mean power for pulse-like BPL signal,
dominated by system noise and impulsive noise between pulses.

Figure D-52 shows a BPL signal that (the mean power being less than 5 dB
above mean system noise power) appears Gaussian noise-like and is
present at least 90% of the time. Since the system noise may contribute
significantly to the measured power, the mean measured signal power
(*M*~s~) is determined by subtracting the mean system noise power from
the mean power for the BPL-on data.

![](media/image48.png){width="5.999305555555556in"
height="4.499305555555556in"}

Figure D-52: Gaussian noise-like BPL signal data, the mean of which is
less than 5 dB above the mean system noise.

Figure D-53 shows a BPL signal where the power appears randomly
distributed with a variance less than system noise. Because the mean
power of the signal is greater than 10 db above the mean system noise
power, the system noise contributes little to the measured power, and
therefore, the mean measured signal power (*M*~s~) is determined only
from the measured powers of the BPL-on case.

![](media/image49.png){width="5.999305555555556in"
height="4.499305555555556in"}

Figure D-53: Randomly distributed BPL signal power, the mean of which is
greater than 10 dB above the mean system noise.

**D.5 GAIN AND NOISE FIGURE CALIBRATION USING A NOISE\
DIODE**

The RF paths to the E4440 Spectrum analyzers (see Figure D-1) were
calibrated by injecting noise with a known excess noise ratio at the
antenna input, collecting power data across the frequency range of
interest, then terminating the input with a 50 terminator, and
collecting the power data once again across the same frequency range.
Power data were collected by putting the spectrum analyzer in zero span
with average power detection and a sweep time long enough to produce a
flat trace. Using an automated stepped frequency measurement routine,
power levels were measured at approximately 200 kHz intervals across the
band of interest. Using the Y-Factor method of calculation (as described
below), both the gain through the system and noise figure at the input
were determined. All power levels were referenced back to the antenna
input by subtracting the gain.

Measurement system calibration should be performed prior to acquisitions
where absolute values are required. As measurements are performed, gain
corrections may be added automatically to every data point. For
measurement system noise figures of 20 dB or less, noise diode Y-factor
calibration may be used. The theory and procedure for such calibration
are described herein.

![](media/image50.wmf){width="4.990277777777778in"
height="2.75in"}Figure D-54: Lumped component diagram of noise diode
calibration

The noise diode calibration of a receiver tuned to a particular
frequency may be represented in lumped-component terms as shown in
Figure D-54. In this diagram, the symbol "" represents a power-summing
function that linearly adds any power at the measurement system input to
the inherent noise power of the system. The symbol "g" represents the
total gain of the measurement system. The measurement system noise
factor is denoted by "nf," and the noise diode has an excess noise ratio
denoted as "enr." (All algebraic quantities denoted by lower-case
letters, such as "g," represent linear units. All algebraic quantities
denoted by upper case letters, such as "G," represent decibel units).

###### Noise factor is the ratio of noise power from a device, n~device~(W), and thermal noise,

$\frac{n_{\text{device}}}{\text{kTB}}$

where k is Boltzmann's constant (1.38·10^23^J/K), T is system
temperature in Kelvin, and B is bandwidth in hertz. The excess noise
ratio is equal to the noise factor minus one, making it the fraction of
power in excess of kTB. The noise figure of a system is defined as 10
log (noise factor). As many noise sources are specified in terms of
excess noise ratio, that quantity may be used.

In noise diode calibration, the primary concern is the difference in
output signal when the noise diode is switched on and off. For the noise
diode = on condition, the power, P~on~(W), is given by:

$p_{\text{on}} = \left( \text{nf}_{s} + \text{enr}_{d} \right)´\text{gkTB}$

where nf~s~ is system noise factor and enr~d~ is the noise diode enr.

###### 

###### When the noise diode is off, the power, P~off~(W), is given by:

$p_{\text{off}} = \left( \text{nf}_{s} \right)´\text{gkTB}$

###### The ratio between P~on~ and P~off~ is the Y factor:

$y = \left( \frac{p_{\text{on}}}{p_{\text{off}}} \right) = \frac{\left( \text{nf}_{s} + \text{enr}_{d} \right)}{\text{nf}_{s}}$

$Y = \text{10}\text{log}(y) = \text{10}\text{log}\left( \frac{p_{\text{on}}}{p_{\text{off}}} \right) = P_{\text{on}} - P_{\text{off}}$

###### Hence the measurement system noise factor can be solved as:

$\text{nf}_{s} = \frac{\text{enr}_{d}}{y - 1}$

###### The measurement system noise figure is:

$\text{NF}_{s} = \text{10}\text{log}\left( \frac{\text{enr}_{d}}{y - 1} \right) = \text{ENR}_{d} - \text{10}\text{log}(y - 1) = \text{ENR}_{d} - \text{10}\text{log}\left( \text{10}^{\frac{Y}{\text{10}}} - 1 \right)$

###### Hence:

$g = \frac{p_{\text{on}} - p_{\text{off}}}{\text{enr}_{d}´\text{kTB}}$

$G = \text{10}\text{log}\left( p_{\text{on}} - p_{\text{off}} \right) - \text{10}\text{log}\left( \text{enr}_{d}´\text{kTB} \right)$

or

$G = \text{10}\text{log}\left( \text{10}^{\frac{P_{\text{on}}}{\text{10}}} - \text{10}^{\frac{P_{\text{off}}}{\text{10}}} \right) - \text{ENR}_{d} - \text{10}\text{log}\left( \text{kTB} \right)$

In noise diode calibrations, the preceding equation is used to calculate
measurement system gain from measured noise diode values.

Although the equation for NF~s~ may be used to calculate the measurement
system noise figure, software may implement an equivalent equation:

$\text{nf}_{s} = \frac{p_{\text{off}}}{\text{gkTB}}$

$\text{NF}_{s} = \text{10}\text{log}\left( p_{\text{off}} \right) - \text{10}\text{log}\left( \text{gkTB} \right)\  = \ P_{\text{off}} - G - \text{10}\text{log}\left( \text{kTB} \right)$

###### Substituting the expression for gain into the preceding equation yields:

$\text{NF}_{s} = P_{\text{off}} + \text{ENR}_{d} - \text{10}\text{log}\left( \text{10}^{\frac{P_{\text{on}}}{\text{10}}} - \text{10}^{\frac{P_{\text{off}}}{\text{10}}} \right)$

The gain and noise figure values determined with these equations may be
stored in look-up tables. The gain values are used to correct the
measured data points on a frequency-by-frequency basis.

Excluding the receive antenna, the entire signal path is calibrated with
a noise diode source prior to a BPL measurement. A noise diode is
connected to the input of the first RF line in place of the receiving
antenna. The connection may be accomplished manually or via an automated
relay, depending upon the measurement scenario. The noise level in the
system is measured at a series of points across the frequency range of
the system with the noise diode turned on. The noise diode is then
turned off and the system noise is measured as before, at the same
frequencies. The measurement system computer thus collects a set of
P~on~ and P~off~ values at a series of frequencies across the band to be
measured. The values of P~on~ and P~off~ are used to solve for the gain
and noise figure of the measurement system in the equations above.

[^1]: If a measurement is attempted and the BPL signal has an
    interference to background noise level (I/N) \< 5 dB, the results
    reported in Subsections D.3.2 -- D.3.6 will be referred to as "Not
    measurable." If a particular measurement isn't attempted, it will be
    reported as "*Not measured*." The 100% duty-cycle power levels
    presented in this report were analyzed statistically from APD
    measurements and therefore did not need to satisfy the requirement
    of I/N 5 dB.

[^2]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^3]: \*

[^4]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^5]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^6]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^7]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^8]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^9]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^10]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^11]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^12]: \* Lines connecting data points illustrate potential trends but
    not expected interpolated values.

[^13]: "Measurements to determine potential interference to GPS
    receivers from ultrawideband transmission systems," J.R. Hoffman,
    M.G. Cotton, R.J. Achatz, R.N. Statz, and R.A. Dalke, NTIA Report
    01-384, Feb. 2001.

[^14]: 1.8 dB was felt to be the first consistently perceptible
    deviation from the system noise curve.