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NIST Technical Note 1550

NIST Technical Note 1550

NIST Tests of the Wireless Environment in

Automobile Manufacturing Facilities

Kate A. Remley

Galen Koepke

Chriss Grosvenor

John Ladbury

Dennis Camell

Jason Coder

Electromagnetics Division

Electromagnetics and Electrical Engineering Laboratory

National Institute of Standards and Technology

Boulder, CO 80305-3328

Robert!. Johnk

National Telecommunication and Information Agency

Institute for Telecommunications Sciences

Boulder, CO 80305-3328

October 2008

^^-^TES O*

'^

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

National Institute of Standards and Technology

Patrick D. Gallagher, Deputy Director
Certain commercial entities, equipment, or materials may be identified in this document in order to adequately describe an experimental procedure or concept. Such identification does not imply recommendation or endorsement - by the National Institute of Standards and Technology, nor does it imply that the entities, materials, or equipment are necessarily the best available for the

purpose.

I

National Institute of Standards and Technology Technical Note 1550

Natl. Inst. Stand. Technol. Tech. Note 1550, 109 pages (October 2008)

CODEN: NTNOEF

U.S. Government Printing Office

Washington: 2008

For sale by the Superintendent of Documents, U.S. Government Printing Office

Internet bookstore: gpo.gov Phone: 202-512-1800 Fax: 202-512-2250

Mail: Stop SSOP, Washington, DC 20402-0001
Table of Contents

Executive Summary

1. Introduction 2

2. Test Set-up 3

2.1 The piiysica! environment 3

2.2 The wireless propagation environment 6

3. Background Ambient Spectrum Analyzer Tests 7

3.1 Measurement set-up 7

3.2 Signal ranges over 24 hours 14

3.3 Ambient signals in key frequency bands 18

4. Spectrum Analyzer Measurements of the 2.4 GHz Frequency Band 27

5. Ultra-Wideband Propagation Measurements 35

5.1 Measurement set-up 35

5.2 Frequency-domain measurements 39

5.3 Time-domain data 41

5.4 Conclusion 48

6. Summary 48

7. References 50

Appendix A: Assembly Plant, Low-Frequency Data, Omnidirectional Transmit and

Receive Antennas 51

Appendix B: Assembly Plant, High-Frequency Data, Directional Transmit,

Omnidirectional Receive Antennas 59

Appendix C: Assembly Plant, High-Frequency Data, Directional Transmit and Receive

Antennas 67

Appendix D: Stamping Plant, Low-Frequency Data, Omnidirectional Transmit and

Receive Antennas 77

Appendix E: Metal Stamping Plant, High-Frequency Data, Directional Transmit,

Omnidirectional Receive Antennas 83

Appendix F: Metal Stamping Plant, High-Frequency Data, Directional Transmit and

Receive Antennas 89

Appendix G: Engine Plant, Low-Frequency Data, Omnidirectional Transmit and Receive

Antennas 97

Appendix H: Engine Plant, High-Frequency Data, Directional Transmit Antenna,

Omnidirectional Receive Antenna 103

Appendix I: Engine Plant, High-Frequency Data, Directional Transmit and Receive

Antennas 109

III

NIST Tests of the Wireless Environment in Automobile Manufacturing

Facilities

Kate A. Remley, Galen Koepke, Chriss Grosvenor

John Ladbury, Dennis Camell, Jason Coder

Electromagnetics Division

Electronics and Electrical Engineering Laboratory

National Institute of Standards and Technology

Boulder, CO 80305-3337

Executive Summary

This report describes measurements carried out by members of the NIST

Electromagnetics Division to study the wireless environment in automotive

manufacturing facilities. Testing was performed at three facilities during 2006 and 2007.

We studied an assembly plant, a very crowded environment having auto chassis bodies

moving continuously along assembly lines; a metal stamping plant, consisting of large

metal-working machinery housed in an older facility; and an engine plant, with a more

modern open, assembly-line layout.

We conducted three types of tests in each plant: (1) A background ambient

spectrum survey where the existing wireless environment in each facility was monitored over a 24-hour period, indicating the current level of radio activity over time at one

location on the factory floor. (2) A spectral analysis of the 802.11b WLAN frequency

band, providing a detailed view of the existing use of this common frequency band. (3)

Reverberant cavity tests where the physical spacing between a source and receiver

was varied to investigate the signal-scattering characteristics of the production floor.

These last tests provided an indication of the level of direct versus reflected path

propagation in the environment. Together, the three sets of tests provided enough

information to characterize the propagation environment for many wireless

technologies.

Background ambient tests of the wireless environment showed signals in expected frequency bands, including broadcast radio and television transmissions,

cellular telephone transmissions, and transmissions carried out within the facilities. In the stamping plant, the background ambient tests also showed signals covering a broad

range of lower frequencies, probably due to machine noise.

Our ultrawideband, synthetic-pulse measurements indicate that these

manufacturing facilities are highly reflective, reverberant environments that can

potentially complicate reliable performance of deployed wireless technology. Even

under line-of-sight conditions, significant self-interference occurs when the transmitter

and receiver are separated by only a few meters or more. When non-line-of-sight

conditions occur, the transmission path becomes very noisy. However, spectrum

analyzer tests conducted throughout the plant indicate that, for the current level of

utilization of wireless technology, coverage can be maintained throughout the plants
when a sufficient number of transmitting and repeating nodes are used. However, if the

use of wireless is to be expanded, interference may become a significant issue.

The measured results provide key parameters that describe the wireless

propagation environment in representative manufacturing facilities. While measurement

uncertainties are not reported, end users of these data are interested primarily in largescale behavior on the order of tens of decibels. Including uncertainties on the order of

±1 dB is of little value when we are studying quantities that can vary by tens of decibels.

Improved channel descriptions will be useful for assessing current and future

deployment of wireless technology in heavy-industrial manufacturing environments, for

standards development, and for qualifying wireless equipment for use in highly reflective

environments such as those studied here. Work is currently underway at NIST to develop laboratory-based methods for qualifying the performance of wireless equipment

for use in highly reflective environments such as those studied here.

1. Introduction

Wireless technology in a production environment offers the potential benefits of

lower installation costs, increased flexibility, and reduced maintenance when compared

to cabled systems. However, the highly reflective, dynamic environment in an

automobile production facility can impede signal reception for wireless devices such as

local-area networks (LANs), equipment-diagnostic tools, plant-floor controllers, and

RFID tags and readers. This may hinder the automotive industry and other U.S.

industrial sectors from taking full advantage of the increased efficiency, reliability, and

economy of wireless networking. A first step to improving the implementation of wireless

networks and control at automotive manufacturing facilities is to evaluate the

propagation environment by carrying out precise measurements at appropriate

frequencies.

Members of the NIST Electromagnetics Division conducted detailed studies of

the wireless environment in three automotive manufacturing facilities: an assembly

plant, an engine plant, and a metal stamping plant. Tests were conducted on August 4-

6, 2006 and August 3-6, 2007. Three types of tests were carried out at each facility.

First, we conducted a spectrum survey, where we monitored existing ambient signals in the environment over a 24-hour period. These "background ambient" measurements

provide an indication of the current level of radio activity minute-by-minute at a

representative location on the factory floor. The second set of tests measured the

spectral activity at several locations throughout the facilities. These tests focused

specifically on the 2.4 GHz industrial, scientific, and medical (ISM) unlicensed frequency

band. Automotive plant wireless system engineers have expressed interest in additional

utilization of systems in this band for telemetry and control on the production floor. The third set of tests studied the scattering characteristics of the factory

environment by use of a test source and receiver. The response of the environment to a

pulse-like signal was measured, giving an indication of the level of direct versus

reflected path propagation in the environment, as summarized in a metric called the

RMS delay spread. This information can be useful in engineering additional wireless

system deployments and determining the required level of immunity to interference for
new equipment. After an overview of the test set-up, the procedure and results for each

test are discussed below.

2. Test Set-up

2.1 The physical environment

The industrial environments represented by these manufacturing plants contain

metallic structures and objects that can have a profound effect on radio reception.

Transmitted radio signals reflect off objects before arriving at the radio receiver, and in so doing they can create interference. The size, shape, and materials of the factory

environment will impact radio reception. An understanding of the physical environment

can help to explain the measurement results and will enable development of appropriate

lab-based tests to replicate these environments.

The first set of tests was carried out in an assembly plant whose dimensions are approximately 500 m x 250 m (1600 ft x 750 ft). The building is about 15 m (45 ft) high

and constructed out of metal. The receiving site ("R" on Figure 2-1 below) for the

background ambient tests, at Test Point "x", was about 70 m (210 ft) from the left end of

the building near columns "S7" and "S8". The column indicators are noted on the left and upper side of the figure. For the scattering tests, a cart carrying the transmit

antenna moved down aisle "S" approximately 300 m (1000 ft) from the receiving

location.

8 11 14 17 20 23 27

w

. u ^

- Q

xR

N

L

J

^ H

-500 iti

FD

-250 m

x Background ambient test site o 2.4 GHz tests

Path for scattering tests (R = receiver)

3,12 Column locator indicators

Figure 2-1: Rough outline of assembly plant where NIST wireless testing was carried out. The plant contains numerous assembly lines, catwalks, and other metallic objects and

structures. The location of NIST receiving equipment for the background ambient tests is marked by an x. The dashed line indicates the path taken during the reverberant cavity

tests. The locations of the 2.4 GHz spectrum analyzer tests are marked with circles.
The second set of tests was carried out in a metal stamping plant, referred to as

the stamping plant in what follows. This facility contains large metal-working machinery,

along with racks of parts, assembly lines, and offices. About half of the building dates to the 1940s, and the other half was added in the 1990s. The building is divided into large

sections, as shown below in Figure 2. The dimensions of the building are approximately

850 m X 760 m (2800 ft x 2500 ft). The building was about 15 m (45 ft) high. The newer

portion is constructed of metal with a concrete floor and the older section is a mix of

cinderblock, metal, and windows with floors of either concrete or wood. Our tests were

conducted in different areas of the building: The receivers for our background ambient

tests were set up at location "x" in Figure 2-2; a cart carrying the transmit antenna

moved along the path denoted by a dashed line for the scattering tests; and the

2.4 GHz spectrum analyzer tests were conducted throughout the facility at locations

marked with circles.

50 t

40

30

-750 m

20

10

*

r

1 BCD E F H

^ -850 m

X Background ambient test site o 2.4 GHz tests — Path for scattering tests (R = receiver)

G,12 Column locator indicators

Figure 2-2: Rough layout of the stamping plant where NIST wireless testing was carried

out. The plant contained assembly lines, heavy machinery, parts racks, and other metallic

objects and structures.

The third building was an engine assembly facility, referred to as the engine plant

in what follows. This facility has a more open layout than the stamping plant or the

assembly plant, with low-profile assembly-lines throughout the building. This is a very

new facility, constructed in 2000. Its dimensions are approximately 215 m x 305 m

(700 ft X 1000 ft). The ceilings were approximately 15 m high and made of metal. Again,

we carried out each set of tests in various parts of the facility. The receivers for the

background ambient tests were conducted at the location marked with an "x" on Figure

2-3; the cart with the transmit antenna for the scattering tests moved along the path
marked with a pink dashed line; and the 2.4 GHz spectrum analyzer tests were

conducted throughout the facility at locations marked with circles.

10 12 14 16 1^ 20 22

Q

PN

M

LK

JH

G

FE

D

1I. _ K

"

-215 m

-300 m

X Background ambient test site

2.4 GHz tests

Path for scattering tests (R = receiver)

H,i2 Column locator indicators

Figure 2-3: Layout of the engine plant where NIST wireless testing was carried out. The

plant was more open than the assembly and stamping plants, although there were numerous assembly lines, parts racks, mobile fork trucks, and other metallic objects and

structures.

This facility is relatively open. Large machinery is located throughout the

structure, but most machines were spaced several meters apart, connected by

assembly lines. A number of metallic objects and surfaces are located throughout the

facility including testing machinery, metal platforms, fences, beams, and conveyors, as

well as mobile forklifts and maintenance vehicles.

The stamping plant and the engine plant are much more open than the assembly

plant we tested in 2006. Both have wide aisles and areas containing racks of parts.

Because both plants had certain areas that were more crowded with machines, we

carried out a number of the 2.4 GHz tests in these areas to study radio coverage and

interference.

We would expect that large metal buildings like these with expansive metal

surfaces and a very complex maze of reflective machinery would cause radio signals to scatter erratically or reverberate throughout the structure. These various signals travel

in multiple complicated paths from transmitter to receiver. These multiple signal paths,

known simply as 'multipath', typically involve different distances depending on how

signals of a given frequency reflect off the metal surfaces. The concept of multipath is illustrated in Figure 2-4. When multiply reflected signals arrive at the receiver, they

arrive at slightly different times. They may either add or subtract from the direct path

signal, causing constructive or destructive interference, respectively. When the
interference becomes severe, radio communication may be lost. When the reflecting

surfaces are in motion the received signal strength is even more variable. A good

understanding of the relationship of these multipath signals to the direct (desired) signal

is important in developing wireless systems that would work reliably in this environment.

automobile

in production Assembly line

Assembly line automobile

in production^

Figure 2-4: Multiple reflections (multipath) occur when signals propagating between the

transmitter and receiver reflect off metallic objects or structures. The different paths cause

the signals to arrive at the receiver at slightly different times.

2.2 The wireless propagation environment

As described above, the physical environment in all three facilities was quite

reflective. This means that even weak radio signals from transmitters located a distance

away could be received and could potentially interfere with desired radio signals.

Knowledge of what radio technologies are deployed on the production floor can help

interpret the measured results.

One primary use of radio technology in these facilities is for broadband data

transfer by use of a wireless local-area network (WLAN). These plants use the IEEE

802.11bTM or 802.11aTM standards [1-3]. The 802.11b standard consists of eleven

channels operating on frequencies between 2.4 GHz and 2.472 GHz. These are considered "wideband" systems, since each channel spans about 20 MHz of spectrum

to provide rapid data transfer. In comparison, a "narrowband" system may occupy only a few kilohertz to approximately a megahertz of spectrum. For all three plants studied, the

WLAN transceivers (or nodes) were tuned to channels 1, 6, and 11. This is standard

practice for minimizing interference between nodes. The nodes used in these facilities are mounted high overhead to provide the best line-of-sight radio connection between

nodes. The 2.4 GHz "Industrial, Scientific, and Medical" (ISM) frequency band is unlicensed, which means other applications such as cordless phones, handheld
wireless games, as well as industrial control and telemetry equipment, can operate in this band.

Other wireless systems commonly used in industrial facilities include handheld

radios for point-to-point communications. These radios are often used by maintenance

and operational personnel for voice communications. These operate in the 900 MHz

ISM frequency band. Cellular telephones used by staff operate at frequencies around

850 MHz and 1.9 GHz. Cordless phones and other consumer electronics operating in the 5.2-5.9 GHz ISM unlicensed frequency band may also be used. At lower

frequencies, radio interference from heavy equipment ("machine noise") can impact

signals. The tests below let us study these frequency bands to determine the level of

interference between different systems in a particular band.

3. Background Ambient Spectrum Analyzer Tests

3.1 Measurement set-up

Reception of desired wireless signals can be affected by users in a given

frequency band as well as by out-of-band signals. Background ambient tests help to provide an understanding of the current wireless environment in a given facility,

including potential in-band and out-of-band interference. This knowledge can be used to help mitigate existing interference issues, as well as to help ensure that future

deployment will not face insurmountable interference.

Figure 3-1 describes the measurement system used in our tests. A spectrum

analyzer captured the ambient signals emitted by wireless devices, broadcast stations,

and from unintentional emitters such as motors in machines. We were interested

primarily in frequencies below 6 GHz, since these are the frequencies currently used for

unlicensed voice and data wireless transmission. We recorded signals from a fixed

location over 24-hour periods. For our first set of measurements in the assembly plant,

we recorded signals over two 24-hour periods. We found little difference between data

from one day to the next. Consequently, we recorded signals over one 24-hour period in the stamping and engine plants.

In each plant, we used three spectrum analyzers: one for the lower frequencies

(20 MHz to 1.3 GHz), one for mid-range frequencies (1 GHz to 6 GHz), and a third to monitor the higher frequencies (6 to 18 GHz). For the highest-frequency set-up, we

were aware that the combined broad frequency band and low antenna sensitivity would

result in a high noise floor. As a result, these measurements can identify only high-level

signals in this band.

In the assembly plant tests, we used omnidirectional antennas for all three

frequency bands. In the stamping plant and the engine plant, we used omnidirectional

antennas in the lowest and highest frequency bands and directional antennas for the

middle band. In all cases, measurement data were collected continuously over the

length of the test. This extended period for data collection tells us whether wireless

traffic changes throughout the day; for example from production times to non-production

times. The test site in each plant is indicated by the red "x" in Figures 2-1 through 2-3.

Figure 3-2 shows a layout of the test equipment in the assembly plant, and Figures 3-2
and 3-3 show photographs of the measurement set-ups in the stamping and engine

plants.

Signals from

production floor

Spectrum analyzer

Figure 3-1: Background ambient tests use a spectrum analyzer to measure signals

from all types of wireless devices, from broadcast stations, and from unintentional

emitters such as large machines over a long period of time.

7 ^ automobile

in production Assembly line

Assembly

line

V

Spectrum

analyzers

(inside

office)

Receive

antennas

(on roof of

office)

Assembly line automobile

in production^

Figure 3-2: Antenna and receiver locations for background ambient tests at the assembly

plant. As shown in Figure 2-1 , the office where the receivers were located was on aisle "S."

8
(a)

(c)

Figure 3-3: Background ambient tests carried out at the stamping plant, (a) A midfrequency-range directional antenna located on a second-story-office roof is shown by the

right-hand circle. A low-frequency, omnidirectional antenna was mounted between

platforms, and is shown by the left-hand circle, (b) An omnidirectional antenna used for the

high-frequency band was mounted on the platform to the left of the directional antenna in (a), (c) The second-story office where the three spectrum analyzers were located.
(a) (b)

(c)

Figure 3-4: Background ambient tests carried out at the engine plant. The antennas and

measurement system were located on a catwalk approximately 15 m above the plant floor,

(a) A mid-frequency-range directional antenna, (b) A low-frequency, omnidirectional antenna

was mounted on the catwalk hanging down over the production floor, (c) The three spectrum

analyzers were located on the catwalk as well.

The spectrum analyzers were programmed to acquire approximately 100 data

sweeps every minute, and each sweep consisted of 8192 frequencies. Every 100

sweeps, a computer program calculated the average and maximum at each frequency

and saved these data files. Thus, we have a representation of the average and

maximum every minute throughout one (approximately) 24-hour period. The recording

10
times are listed in Table 3-1 below. At the stamping plant, the different start and stop

times occurred due to technical issues. The operational schedules for these facilities

during these times are shown in Table 3-2.

Table 3-1: Start and stop times for the background ambient tests.

Assembly Plant Run #2 (2006)

Frequency

band

Start: Friday

August 4

Stop:

Saturday

August 5

Low 8:30 a.m. 7:15 a.m. Mid 8:30 a.m. 7:15 a.m. High 8:30 a.m. 7:15 a.m.

Stamping Plant (2007)

Frequency

band

Start: Friday

August 3

Stop:

Saturday

August 4

Low 1:25 p.m. 12:08 p.m.

Mid 1:26 p.m. 12:09 p.m.

High 10:36 a.m.

8:21 p.m.

(August 3)

Engine Plant (2007)

Frequency

band

Start: Sunday

August 5

Stop:

Monday

August 6

Low 1:45 p.m. 1:05 p.m.

Mid 1:45 p.m. 2:34 p.m.

High 1:47 p.m. 2:49 p.m.

11
Table 3-2: Production schedules during the background ambient tests. Left side: assembly and engine plants. Right side: stamping plant.

Assembly Plant Stamping Plant

Aug 3-5, 2006 Aug 3, 2007

Day Shift 1st shift

Start: 6:00 a.m. Shift Start: 7:00 a.m. Break: 9:30 - 9:45 a.m. Break: 9:00 -9:16 a.m. Lunch: 11:00 - 11:30 p.m. Lunch #1: 11:30 AM -12:00 p.m. Break: 1:00 - 1:15 p.m. Lunch #2: 11:45 AM- 12:15 p.m.

Shift End: 2:30 p.m. Cleanup: 2:55 - 3:00 p.m.

Afternoon Shift Aug 3, 2007

Start: 3:30 p.m. 2nd shift

Break: 5:30 - 5:45 p.m. Shift Start: 3:00 p.m. Lunch: 9:00 - 9:30 p.m. Break: 5:00 -5:16 p.m. Break: 10:45 - 11:00 p.m. Lunch: 7:30 -8:00 p.m.

Shift End: 12:00 a.m. Cleanup:

Aug 3-4, 2007

3rd shift

Shift Start: Break:

Lunch:

Cleanup

10:55 -11:00 p.m.

11:00 p.m.

1:00 -1:16 p.m. 3:30 -4:00 p.m. 6:55 -7:00 p.m.

Engine Plant

Aug 5-7, 2007

Shift Start: 6:00 a.m.

Break: 9:00 - 9:15 a.m. Lunch: 11:00 - 11:45 a.m. Break: 1:30 - 1:52 p.m.

Shift End: 4:30 p.m. Aug 4, 2007

1st shift

Shift Start: 7:00 AM

Break: 9:00 -9:16 a.m. Lunch #1: 11:30- 12:00 a.m. Lunch #2: 11:45 a.m.- 12:15 p.m. Cleanup; 2:55 -3:00 p.m.

The background ambient data presented below have been corrected for the

antenna characteristics and represent the actual electric field strength (in dB relative to

1 v/m) incident on the antenna. The antenna factors used are shown in Figure 3-5. The

antenna factor represents the transfer function of the antenna from incident field

strength to terminal voltage. We apply the antenna factor to the measured power

recorded by the spectrum analyzer to determine the electric field strength picked up by

the antenna. The antenna factors for these antennas were determined from direct

measurements using the two-identical antenna method on the NIST open-area test site.

In practice, the antenna factor is valid for a particular aspect angle and will vary

depending on the directional gain of the antenna. The antenna factors for the

omnidirectional antennas are strictly valid only in the horizontal plane (zero-degree

elevation angle) and, depending on the arrival angle of the radio wave, could be several

decibels in error. Fortunately, the directional gain of these antennas is such that the

zero-degree elevation angle antenna factor appears to be a reasonable average value over all the aspect angles. Notice in Figure 3-5 that the antenna factors are quite large

at the higher frequencies, which makes it difficult to detect weak signals. The noise floor

12
of the spectrum analyzer is relatively constant witli frequency; so the minimum signal

we can measure is determined essentially by the antenna factor curve.

70

60

50

S" 40

2_ 30 o

S. 20

rei 10 1

-10

-20

-30

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70

60

50 m 40

2_ 30 o

2. 20

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-20

-30

0.01

0.10 1.00 Frequency (GHz)10.00 100.00

(a)

1

L

1 east Sens itive >

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I na- :'/S^* / "".W

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"s \ /| 'v.^^

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v.^

ll 1

1

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1 1

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0.10 1.00 Frequency (GHz)10.00 100.00

(b)

Figure 3-5: Antenna factors for the receiving antennas used in the (a) assembly plant and

(b) stamping and engine plants. In the assembly plant, we used the same antenna type for

the mid- and high-band measurements.

Note that throughout this work, measurement uncertainties are not reported. End

users of these data are primarily interested in large-scale statistical behavior on the

order of tens of decibels. Including uncertainties on the order of 1 dB is of little value

when we are studying quantities that can vary by tens of decibels.

13
3.2 Signal ranges over 24 hours

To summarize the large amount of data collected, we processed the recorded

data. Each data file contained the average or maximum received signal at each

frequency over a one-minute interval, and stored over the duration of the entire

measurement (approximately 24 hours). Thus, at each frequency, we collected a set of over 1200 time samples. We then took the minimum and maximum of those time

samples to obtain an overall minimum and maximum at each frequency. This leads to some admittedly confusing terminology when we refer to the maximum of the maxima,

the maximum of the averages, or the minimum of the maxima.

Figures 3-6 and 3-7 show the extreme values of the (a) maximum and (b)

average field measured over the entire spectrum from 20 MHz to 18 GHz for all three

sites. As expected, no strong signals were detected above 6 GHz. However, the noise

floor of the instruments increases significantly with frequency.

14
20

i"

ooi -40

a. <

M -60 c

O)

-80

-100

T 1

,1

1 1 1 1 III 1 1 1 M 1 II 24 Hour Period

Signal Characteristics

1 1 Mill 1 1 M 1 Ml

,

-^ No. ;e Floor \

• Ma" of Maximum; j --*- Mm of Maximums ! J J

jl

^

• liir

t| i ('I k

1

1

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-80

0.10 1.00 Frequency (GHz)

(a)

10.00 100 00

-100

Si

1 1 24 ^ gnalIII 1 1 1 1 1 II ^our Period

Characteristics

1

1 M 1 It -— Nolso Floor

- Hm of AvAr;gqfl5 —Mtnof Av<^ran«s

ii,

1

,1 1 J« M i

rtitf

s

1 \ h

f

A.

1

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001 0.10 1.00 Frequency (GHz)

10.00 100.0

(b)

Figure 3-6: 24-hour signal amplitudes at the assembly plant. In (a), we computed the

maximum of all recorded data collected during each minute, and then computed the

minimum (dark blue curve) or maximum (light green curve) of each value over the 24-hour

period. In (b), we computed the average of all recorded data collected during each minute,

and then computed the minimum (dark blue) or maximum (green) of each value over the 24-

hour period. In each graph, the noise floor is plotted in red.

15
24 Hour Signal Characteristics

Frequency {GHz)

(a)

24 Hour Signal Characteristics

0-

1 :

1 1 -10 Max of Averages | -20-

^-30. --

1 d

1;

a >6i

Ml , k u^

il

:!S*V 3 "^° cw -70

-80 1 i\

/^

•Nj

ih J II 1^

liii u

r

-100 r g

0.01 0.1 1 10 100 Frequency (GHz)

(b)

Figure 3-7: 24-hour signal amplitudes at the stamping plant. In (a), we computed the

maximum of all recorded data collected during each minute, and then computed the

minimum (dark blue curve) or maximum (light red curve) of each value over the 24-hour

period. In (b), we computed the average of all recorded data collected during each minute,

and then computed the minimum (dark blue) or maximum (red) of each value over the 24-

hour period.

16
24 Hour Signal Characteristics

S -50 a

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ill 1 Jy

[r j^^jIlS ----- -mm

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24 IHour Signal Characteristics

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i

i i

1 ^?

,y "i , r

w

yill

J^!y

-120 __ _ _

Frequency (GHz)

(b)

Figure 3-8: 24-hour signal amplitudes at the engine plant. In (a), we computed the maximum

of all recorded data collected during each minute, and then computed the minimum (dark

blue curve) or maximum (light red curve) of each value over the 24-hour period. In (b), we

computed the average of all recorded data collected during each minute, and then computed

the minimum (dark blue) or maximum (red) of each value over the 24-hour period.

17
3.3 Ambient signals in /rey frequency bands

The data collected for this evaluation of the wireless environment represent a comprehensive evaluation of the electromagnetic environment at a specific location

within each plant. We briefly summarize some of our relevant findings for devices

employed in production facilities such as these. We also discuss our methods for

processing and presenting the results.

We begin by examining two of the frequencies in and near the FM broadcast

band. These two frequencies are representative of the typical signal characteristics

throughout the measured spectrum. Figure 3-9 shows the measured field over time at 106.7 MHz (an active FM radio channel) and at 109.0 MHz (slightly above the FM band

with no apparent communication activity). The amplitude of the 106.7 MHz signal is roughly stable between -55 dBv/m and -40 dBv/m. The red curve represents the

maximum observed signal over 100 samples, and the blue curve represents the

average observed signal. The offset between these two curves is roughly constant at around 4 dB.

Surprisingly, we see that the variation of the 106.7 MHz signal with time

correlates well to the general operation of the plant, with lower levels observed while the

assembly line was shut down. At 109.0 MHz, the readings are essentially at the noise

floor of our instrumentation, with occasional spikes thrown in. Again the maximum

observed signal is approximately 4 dB higher than the average, although the spikes

show a much larger difference (as large as 20 dB). This indicates that the spikes are

rare events, occurring only once or twice out of 100 samples. Since little information

appears to be lost by examining the maximum observed signal, but using the average

tends to diminish the effect of the spikes, we will focus on the maximum observed signal

for the remainder of our analysis.

Presenting data similar to those shown in Figure 3-9 is not a tractable option for

the more than 24,000 frequencies that we measured. Instead, we took a time series at

several key measurement frequencies, similar to those shown in Figure 3-9, and

computed five statistics: the minimum, the 25**^ percentile or lower quartile, the median,

the 75**^ percentile or upper quartile, and the maximum. Together, these five statistics are referred to as a "five-number summary" of a set of data. Such a summary obviously

loses information such as when a transition occurs or the duration of any transition, but

does indicate how often an interfering signal might be present. For the 106.7 MHz and

109.0 MHz signals, the minimum, lower quartile, median, and upper quartile are tightly

grouped (approximately 5 dB variation) but the maximum is significantly higher

(sometimes over 20 dB higher) than the upper quartile, indicating that high-amplitude

signals are rare. Communication around a frequency that shows very little activity is possible as long as error correcting/detecting methods are used to recover from the

occasional noise spike.

Figure 3-10 shows the five-number summaries for frequencies in the FM

broadcast band. For each channel, the characteristics are similar to those of the

106.7 MHz channel. Between channels, the characteristics are similar to those shown at 109.0 MHz.

18
11:00 AM 1:00 PM 3:00 PM 5:00 PM 7:00 PM 9:00 PM 11:00 PM 1:00 AM 3:00 AM 5;00 AM 7:00 AM 9:00 fi Time

Figure 3-9: Maximum and average ambient signals at 106.7 MHz and 109 MHz from the

assembly plant measured over a 24-hour period August 3-4, 2006.

8/4/2006 Maximum Quartiles Over a 24 Hour Period - Low-Band -^"'^x —0.75

median -^0.25 -^min

Steady signal: even minimum

90 92 94 96 100 102 Frequency (MHz)

Figure 3-10: Ambient signals represented by a five-number summary in the FM broadcast

band between 90 MHz and 110 MHz measured in the assembly plant and collected over a 24-hour period, August 3-4, 2006.

19
If several frequencies in a band have similar characteristics, we can overlay the

traces to illustrate the comnnonalities. For example, Figures 3-11 (a) through (c) show an

overlap of all 43 frequencies measured between 20 MHz and 25 MHz at the three

facilities. In 3-1 1(a), we see good correlation between the activity in the assembly plant

and the level of electromagnetic emissions. The curves from the stamping and engine

plants in 3-1 1(b) and (c) show three different characteristics: periods of low activity,

periods of extended high activity, and short spikes of very high activity, possibly due to someone passing by the receiver site or a spil<e in the power or activity on the

production floor. The broadband nature of the extended characteristics, along with the

timing of the low-activity periods, indicates that the observed signals may be related to machinery that are energized during certain times of plant operation and either turned

off or not operated during breaks. For example, the time window between 11 p.m. and

5:30 a.m. in the stamping plant indicates that certain machinery may not be used during

the third shift. We next examine some of the frequency bands of interest to wireless

communication engineers. Figures 3-1 2(a), (c), and (e) show a three-dimensional

representation of the signals around 5.8 GHz for the three facilities. We plot amplitude versus both frequency and relative time (number of minutes after the start of the

measurement). Figures 3-1 2(b), (d), and (g) show the five-number summaries over the

same frequency band for the three plants.

In the assembly plant and the stamping plant, we see bursts of signal activity in this frequency band. Activity in the stamping plant occurs regularly, less so in the

assembly plant. The signals cover a broad frequency range, but occur infrequently

during the 24-hour period. Both types of graphs support this conclusion. For the engine

plant, we see that the 5.8 GHz frequency band is not currently in use.

20
11:00 AM 1:00 PM 3:00 PU 5:00 PM 7:00 PM 9:00 PM 11:00 PM 1:00 AM 3:00 AM 5:00 AM 7:00 AM 9:00 AM

Time

(a)

1:25 PM 3:49 PM 6:13 PM 8:37 PM 11:01 PM 1:25 AM 3:49 AM 6:13 AM 8:37 AM 11:(M AM 1:25 F Time

(b)

(c)

Figure 3-11: An overlay of the 43 measured frequencies between 20 MHz and 25 MHz

collected during a 24-hour period at (a) the assembly plant, August 3-4, 2006, (b) the

stamping plant, August 3-4, 2007 and (c) the engine plant, August 5-6, 2007.

21
Af*** ^

(a)

10

-10 £ -20

-30 i^o

Q- -50 J-eo

1-70

m

CO

-80

8/4/2006 Maximum Quartiles Over a 24 Hour Period Mid-Band

5,5 5,55 5,6 5,65 5,7 5,75 5,8 5,85 Frequency (GHz)5.9 5,95

(b)

'f^a

Ctiio)

<^^^^ =?=^^

(c)

Maximum Quartiles Over a 24 Hour Period

,0t»r^»m-*^p'*^*t'mMfJf*>*n,tmk »' M»**w^ U. «< *»Mpi jyA w H*.^ »»»» «l

5.5 5.55 5 6 5 65 5 7 5 75 5 Frequency (GHz)

5.85 5 9 5 95

(d)

1 Quartiles Over a 24 Hour Period "TlQ

<tiin)

(e)

" —Min

0.25 —Median

-10 -

0.75 —Max

i

-30 -1

—

: ^

•'—-*--..^

:r: "

<~M^

-so « —

-70 J

5.5 5.55 5.65 5.7 5,75 5.8 Frequency (GHz)

5.9 5.95

(f)

Figure 3-12: Received signal levels at 5.8 GHz collected over a 24-hour period. Left

column: Signal level versus frequency (right axis) and time (left axis) for the (a) assembly

plant, (b) stamping plant, and (e) engine plant. Right column: A five-number summary of

the same data for (b) assembly plant, (d) stamping plant, and (f) engine plant.

22

i
The frequency band from 902 MHz to 928 MHz is often used for handheld

wireless communication in industrial plants, while cell phone communications may be

found in the 800 MHz frequency range. Figures 3-13(a)-(f) show radio activity in these

bands. In the assembly plant, we see a great deal of activity in the 900 MHz band

arising from plant floor communications. However, both the stamping plant and engine

plant show little activity, with intermittent activity in the 800 MHz cellular band.

rtcy <<''nJ^

^ J'x

^^i*=> -^

(a)

Frequency (MHz)

(b)

"^^ \s^ <#» •"'^"s.

(c)

1

=E'" -

ll III

1

f

Rn T

1 l[irtteti ii| ^^^^

Frequency (MHz)

(d)

Frequency (MHz)

(e) (f) Figure 3-13: Received signal levels at 900 MHz collected over a 24-hour period. Left

column: Signal level versus frequency (right axis) and time (left axis) for the (a) assembly

plant, (b) stamping plant, and (e) engine plant. Right column: A five-number summary of the

same data for (b) assembly plant, (d) stamping plant, and (f) engine plant.

23
The spectrum usage around 2.4 GHz is shown in Figure 3-14. In Figure 3-14(a)

and (c), the 3-D representation shows high-level signals at certain frequencies. For the

engine plant, Figure 3-1 3(e), we see consistent, low-level use of the 2.4 GHz band

across the entire band (Figure 3-14(c)). The median in Figure 3-14(f) clearly shows one

of the WLAN channels being used. The remainder of the usage is probably due to some

other type of transmission system involving a frequency-hopping transmitter.

(a)

E -20 5

S -30

a- -50-1*

8/4/2006 Maximum Quartiles Over a 24 Hour Period Wicf-Band

> II , hjiJhj-y..:^^

2,45 Frequency (GHz)

(b)

— 0.75 med

--0.25

(c)

2 45 Frequency (GHz)

(d)

^i^''] ""Tie 'fiil^^^

(T,!,,) .,1 rf^'Vl

0,25 —MetSan ? w "1 —Max

1 ,y 1

-50- „__JL.fn^ L U««c.^ , ,

n

Freouencv (Ghiz) (e) (f)

Figure 3-14: Received signal levels at 2.4 GHz collected over a 24-hour period. Left

column: Signal level versus frequency (right axis) and time (left axis) for the (a) assembly

plant, (b) stamping plant, and (e) engine plant. Right column: A five-number summary of the

same data for (b) assembly plant, (d) stamping plant, and (f) engine plant.

24
Figure 3-15 shows low-frequency ambient signals from 10 MHz to 400 MHz.

Below 400 MHz, the entire spectrum appears to be filled with noise, with a few obvious

communication signals. For the stamping plant, there are several higher-level,

intermittent signals at the lower frequencies. Much of this noise is probably related to the older, heavy machinery used in plant operations.

(a)

Frequency (MHz)

(b)

- 0^

Medan

0.75 Max

i,

M

n ii 1,1,1 bill 1 J I , Li 1 [} IffftWiilJj iililijJkijB^^ Uil^ 1iSfflfj'^l'*'''^1 STEaJjMW

IT ^BHUiiiKli,, k

jjj^ lljl pat^'^"t^yte

f "^^Wl Mi i }0fl^^

f 'wm'^t

200 250 Frequency (MHz)

(c)

Figure 3-15: Low-frequency data (10-400 MHz) from (a) the assembly plant, (b) the

stamping plant, and (b) the engine plant. Data were collected over a 24-hour period.

25
At 1.9 GHz, see Figure 3-16, (probable cell phone traffic) we see characteristics

common to all plants. Below 1.95 GHz, the signals are less consistent, with high

maxima, but low levels for the other statistics. These are likely transmissions from

nearby individual cell phones. The lower-level signals are probably from a base station.

Figure not available

1.88 1.9 1.92 1.94 1.96 1.98 Frequency (GHz)

(a) (b)

96 t 98 2 Frequency (GHz)

(C) (d)

Frequancy (Ghlz)

(f)

Figure 3-16: Received signal levels at 1.9 GHz collected over a 24-hour period. Left column:

Signal level versus frequency (right axis) and time (left axis) for the (a) assembly plant (not

available), (b) stamping plant, and (e) engine plant. Right column: A five-number summary of

the same data for (b) assembly plant, (d) stamping plant, and (f) engine plant

26

i
The background ambient results presented here show wireless activity in expected frequency bands. The levels of activity seem very well defined. Broadcast

stations can be received within the older stamping plant building, primarily because of

the number of windows in this facility. Machine noise seems to be a significant issue in the stamping plant, but not the engine plant, at the locations studied. The 5.8 GHz band

gets intermittent-to-little use. This may change as more wireless technology is deployed

at these frequencies. We studied the 2.4 GHz band in more detail below.

4. Spectrum Analyzer Measurements of the 2.4 GHz

Frequency Band

Many types of wireless equipment utilize the 2.400 GHz - 2.484 GHz unlicensed

frequency band, including WLAN systems used for data transfer, specialized equipment

on the factory floor, and personal electronics, such as wireless handheld games or cordless phones. All of these different uses can lead to radio interference that can

impair or even disable critical manufacturing equipment. Use of additional transceiver

nodes to overcome interference or to fill in "dead spots" can actually create additional

interference, especially in highly reflective environments, and must be positioned

carefully. To provide additional insight into current use in this common frequency band

on the production floor, we collected spectrum analyzer "snapshots" at locations

throughout all three plants in the frequency range between 2.4 GHz and 2.5 GHz, as

illustrated in Figure 4-1.

For these measurements, we used a portable spectrum analyzer connected to an

omnidirectional antenna. Figure 4-2 shows the type of set-up used, although in practice

we used a half-wave dipole antenna mounted on a metallic base for measurements

above 1 GHz. The spectrum analyzer and antenna were carried throughout the plants

and signals were recorded at the locations shown in Figures 2-1 through 2-3.

Measurements were repeated at most locations on two different days. The goal of these

tests was first to evaluate the coverage of existing transmissions throughout the plant,

and second to determine whether there are any significant interfering sources in the

present environment.

Measurements were carried out with the "peak hold" feature of the spectrum

analyzer turned on. This indicated the overall level of signal received at a particular

location over the period for which the peak hold was engaged. Note that the signal

levels presented in the measurement data give only relative values since we did not

correct the measurements for the antenna used.

Note that throughout this work, measurement uncertainties are not reported. End

users of this data are primarily interested in large-scale statistical behavior on the order

of tens of decibels, thus including uncertainties on the order of 1 dB is of little value.

27
Spectrum analyzer

Figure 4-1: Measurement set-up for the handheld spectrum analyzer tests.

Figure 4-2: Photograph of the portable spectrum analyzer and omnidirectional antenna used

to collect snapshots of spectrum throughout the three plants. The antennas shown here were

used at frequencies up to 1 GHz. Other omnidirectional antennas were used at higher

frequencies.

We first show results from a series of measurements along aisle "S" in the

assembly plant (see Figure 2-1). Using the handheld spectrum analyzer and a small

rubber-coated helical monopole (rubber duck) antenna, we moved from column "S7" to column "S17", about 170 m (500 ft.) away. Figure 4-3 shows the results of this set of

measurements. While the 802.11b WLAN signals are very weak at SI 7, they can be

detected almost continuously from S7 to that location. Midway, around S11, we see the

transition from one node operating on channel 6 at 2.437 GHz to another node,

operating on channel 1 1 at 2.462 GHz. Coverage is quite good down the aisle.

28
Spectrum Analyzer

WPM'J „ Ml: 69.60 dBm 01 2400.0 MHz M2: 59.60 dBm @ 2400.0 MHz M4: 79,39d8m @ 246S.0 MHz

Spectrum Analyzer

WP.VIS

M 1 : -90.22 dBm ® 2400.0 MHz M2: -90.22 dBm 01 2400.0 MHz IW4: -90.97 dBm fi) 2465 MHz

!oo .»», -55 -

aB.Ol. -60

soa. -65 -

-70 -

1 --80 -

-85 -

-90 -

-95 -

E

1 1

dB

eak

SOD =». -55-

.B.o. .60 -

5»-. -65 -

-70 -

1 •'-

-80 -

-85 -

-90 -

-95 -

-100 -

2

CF: 2450.0 MF

RBW: 30 kHz

MoxFIold: ON

iMin Sweep Tir

Date: 08/05/20 Model: MS271

1

1

dB

eak

7

r

>9 S

1

1

1 J li 111,

1

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ipjwjj -4/ILl.. ,ll '\\f Ji. J...... i;/l lU liij- u^-vivv •'V'pir "'''^"•"""T''^

= :; 1

,

II. .1 ill.

:- -^°°

1 1 1 1 1 1 1 1 1 1 1 2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 25C Frequency (2400.0-2500.0 MHz)

CF: 2450.0 .MHz SPAN: 100.00 MHz AUenuation: RBW:30kH2 VBW:10kHz Detection: Pos. P MaxHold: ON

Min Sweep Time: 50.00 Micro Sec

Date: 08/05/2006 Time: 11:25:06 Model: MS2711D Serial »: 00421041

1 1 1 1 1 1 1 1 1 100 2410 2420 2430 2440 2450 2460 2470 2480 2490 25C Frequency (2400.0 - 2500.0 MHz)

Iz SPAN: 100.00 MHz Attenuation: VBW: 1 kHz Detection: Pos. P

ne: 50.00 Micro Sec

06 Time: 11:19:42 ID Serial »: 00421041

Spectrum Analyzer WPM7

Ml .69 20 dfim rti) 2400 MHz M?: -89.20 dBm ® 2400.0 MHzM4:.90.86dHm®24650WH

dB

eak

Spectrum Analyzer

WP.V16

S..0 «», -55 -

.8.0.. -60 -

5oa. -65 -

-70 - 1 -"-

-80 -

-85 - 90 -

-95 -

S11 50Q asTM -55 -

ae.o. -60 -

soa! -65 -

-70 - 1

D

1 1

dB

eak

: S13 ^

!

1 1

1 1_ .. 1 1. .

J, J|4(.n . i**^ ..^iXi I U.. M m\. L. f

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»*^^yiw fv\t/^ yJ*K, A.VUV,

-95 -

-100 -£

2'

CF: 2450.0 MF RBW: 30 kHz

MaxHold: ON

Min Sweep Tii Date: 08/05/20 Model: MS271

.vw, ^JLA*V^ ft^dtn^My^^

.., '

III

2

CF: 2450.0 Ml- RBW: 30 kHz

.Ma.xHold: ON

Min Sweep Tin Date: 08/05/20 Model: MS271

1 too 24

z

ne: 50.0

D6ID

10 2420 24

FrSI

) .Micro Sec

1 1 1 1 30 2440 2450 2460 2470 2480 24 equency (2400.0 - 2500.0 MHz) AN: 100.00 MHz Atteni VBW: 10 kHz Detectio

Time: 11:18:27 >eriaU: 00421041

90 250

ation:

V. Pos. P

1 1 1 1 1 1 1 1 1 00 2410 2420 2430 2440 2450 2460 2470 2480 2490 250

Frequency (2400.0 2500.0 MHz)

z SPAN: 100.00 MHz Attenuation: VBW: 10 kFIz Detection: Pos. P

le: 50.00 .Micro Sec

16 Time: 11:14:55 ID Serial »: 00421041

Spectrum Analyzer

WP\15 Spectrum AnalyzerWPVI4

^ , ^Q Ml : .39.84 dBm S) 2400.0 MHZ M2: -89,84 dBm ® 2400.0 MHZ M4: -91.73 dSm @ 2465 MH

-50 «iw -55 -

«9.o« -60 -

!o«. -65-

-70 -

1

-80 - 85 -

-90 - 95 -

1 1

dB

eak

10 asTM -55 -

1

: S15 S17 :

e

65 -

70 -

75 -

80 - 85-

90 -

i

..Di k

fr**^ \ »' . In%K . Ill ^vA/^Y^ Av^rr-t4. '""" ^.^jM/V rtAV^Wr^flif Wkh^ 'AHf,w^

ii'm .1.. lol 11,1

2

CF: 2450.0 Mt

RBW: 30 kHz

.MaxHold: ON

Min Sweep Tir Date: 08/05/20 Model: MS271

1 1 1 1 1 1 1 1 1 »00 2410 2420 2430 2440 2450 2460 2470 2480 2490 25C Frequency (2400.0 - 2500.0 MHz)

Iz SPAN: 100.00 MHz Attenuation: D VBW: 10 kHz Detection: Pos. P

ne: 50.00 Micro Sec

06 Time: 1 1:12 4(. ID Serial,! Ci042ni4l

CF: 2450 RBW: 30 .MaxHold Min Swe

Date: 08/ Model: M

2 OMF

kHz ON

pTin

15/20 S271

1 1 1 1 1 1 1 1 1 100 2410 2420 2430 2440 2450 2460 2470 2480 2490 250 Frequency (2400.0 - 2500.0 MHz)

z SPAN: 100.00 .MHz Attenuation: VBW: 10 kHz Detection: Pos. P

ne: 50.00 Micro Sec

36 Time: 11:09:11 ID Serial ',: 00421041

dB

eak

Figure 4-3: Handheld spectrum analyzer nneasurements made while moving approximately

150 m (500 ft) down aisle S. Note that the center frequency of the 802.11b WLAN signal

changes between S9 and S1 1, indicating reception from another node.

Figure 4-4 shows results of measurements at various locations in the stamping

plant during production. Each graph was collected over a one-minute period on August

3, 2007 using the "peak hold" function on the spectrum analyzer. We see that 802.11b

signals are being transmitted on channels 1, 6, and 11 (center frequencies of

2.412 GHz, 2.437 GHz, and 2.462 GHz). These signals were received at every location

we tested, although in some cases the reception was quite weak, for example, channel

1 in Figure 4-4(c).

29
Spectrum Analyzer

E2?E4 Spectrum AnalyzerK23B

Ml: -126.40 dBm^

-100 -110

-120

-130

-140

-150

:

i \zZ6

m

\

;

:

=

1 1

I L iJ ,i 1 A\ i-^ nki 1 Um uULMfiUji, J A ^

:

=1111 1111 1 1 1 1 1 1 1

1

1 1 1 1 rill II 1 IMI 1 1 1

1

Ml: -108 82 dBm (Sj 2400.0

2400 2410 2420

Min Sweep Time: 1 .00 Milli Sec Dale: Og/03/2007 Model: MS271 ID

2430 2440 2450 2460 2470

Frequency (2400.0 - 2500.0 MHz)

2480 2490 2500

Allcnuation: Dynamic

Deteclton: RMS Average

P^yW A

-120 -=- -130-^

-140 -E-

-150 -p- aM

1 1 1

1

jyi

1 1

1

K23

2400 2410 2420

CF: 2450.0 MHz

RBW: 10 kllz

Sid: Min Sweep Time: 1.00 Milli Sec

Dale: 08.03.2007 Model: MS2711D

2430 2440 2450 2460 2470

Frequency (2400 - 2500.0 MHz) SPAN: 100 00 MHz

VUW: 3 kHz

2480 2490 2500

(a) (b)

Spectrum Analyzer

K31A

: ^1

j Kcil Q

:

E

: i UAJUa '^^J^ J1L LvV. rvVUAVi J u ^ ^^r^*- 4>v*«

:

:

I

150 ^

=1 [ 1 1 1 1 1 1 III' nil MM MM IMI IMI IMI 1 1 1

1

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400 - 2500.0 MHz)

Aitcnuaijon: 10 dB

Detfclion: Pos. pL-ak CF: 2450.0 MHz. SPAN: 100.00 MHz

RBW: 10 kHz VBW : 3 kHz

Sid: Min Sweep Time: 1.00 Milli Sec

Dale: 08/03.2007 Time: 09:00:08 Model: MS27I ID Serial*: 00421041

Spectrum Analyzer

L23

M1:-119 t

17 asm, 12400.0 MHz —

1

t L2c5 1

1

^

F ,1 M III .1 .t fll i'JiLIIUJ dLAtJU sUw -JJiv ^ju4w*\4nv^4vv^

%

Pi 1 1 1 1 1 1 1 till 1 1 1 1 1 1 1 1 1 1 1 1 1 II MM IMI II, 2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400 - 2500 MHz) IMHz SPAN lOllOil MH/ Alienuaiion: I dB

tHz \ liW, 3 kiiz Detection: Pos. Peak Min Sweep Time: 1.00 Milli Set Dale: 08/03 2007

Model: MS27I1D

(C) (d)

Figure 4-4: Handheld spectrum analyzer measurements collected over a one-minute period

in the 2.4 GHz frequency band in the stamping plant. Signals are clearly present in the three

primary WLAN channels throughout the plant, although in some cases they are quite weak.

30 I
We carried out similar tests at the engine plant. We again turned on the "peak

hold" function on the spectrum analyzer and carried out the measurement over an

approximately three-minute window to see what signals were present over a longer

period. Figure 4-5 shows results from representative locations on the production floor.

These data were collected on Sunday, August 5, 2007. A second set of data collected

at the same locations on Monday, August 6, 2007 is shown in Figure 4-6.

Spectrum Analyzer

K16-SUN-2P4-H

-20- fll-95.6 dBm(S 2137.0 M <2 - ^-ll

^0- K1b :

-50 -

00

1 1

° ii 1, 1

1 1 IJJ lAl iL 1 Jlliu jajil i 1 m^A-lilM. IMJl JUlllx. iU

\

-120- 1 1 1

1

1 1 1

1

1 1 1 1

I nil' Nil 1 1 1

1

MM Ml MM 1 1 1 1 2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 25000 MHz)

Allenuation: dB

Detection: RMS Average

CF: 2450.0 MHz

RBW: 30 kHz

MaxHold: ON

Std: Min Sweep Time:

Date; 08/05/2007 Model: MS271 ID

1.00 Mill

SPAN: 100.00 MHz

VBW: 1 kHz

Sec Time: 12:57:09

Serial #: 00421041

(a)

Spectrum Analyzer

Hll-SLrN-2P4-H

dBmca; =^

=T1

^ H11 [

=

=

=

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, 1 1

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:

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1 1 1 1 1 1 1

1

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500.0 MHz)

Attenuation: dB

Detection: RMS Average

CF: 2450.0 MHz SPAN: 100.00 MHz

RBW: 30 kHz VBW: I kHz

MaxHold: ON

Std: Min Sweep Tiine: 1.00 Milli Sec

Date: 08/05/2007 Time: 13:07:02 Model: MS27UD Serial*: 00421041

(c)

Ml: -94.84 .aemO

Spectrum Analyzer

Q17-SON-21'4-H

2437.0 MHz

""

E

'—II

-40 - : o^7 u

jO __

'°

I

1 1 . 1 ll 1 JTMa wfe

J|L|,l|,)lill«l..iil

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1

MM

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500.0 MHz)

CF: 2450.0 MHz SPAN: 100.00 MHz Attenuation: dB RBW: 30 kHz VBW: 1 kHz Detection: RMS Average

Ma.xHold: ON

Std: Min Sweep Time: 1 .00 Milli Sec

Date: 08/05/2007 Time: 12:52:17 Model; MS2711D Serial #: 00421041

(b)

Spectrum Analyzer

I109-SUN-2P4-H

-110

-120

' dBmSJ -i— - — ====T1

H09 p

, 1 <)L » ,. 1 1 . II

1 1 1 2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500.0 MHz)

CF: 2450.0 MHz SPAN: 100.00 MHz Attenuation: dB RBW: 30 kHz VBW: 1 kflz Detection: RMS Average MaxHold: ON

Std: Min Sweep Time: 1.00 Milli Sec

Date: 08/05/2007 Time: 13:11:08 Model: MS271 ID Serial/?: 0042 1041

(d)

Figure 4-5: Handheld spectrum analyzer measurements collected over a three-minute

period in the 2.4 GHz frequency band in the engine plant. As in the stamping plant, signals are present in the three primary WLAN channels throughout the plant. Other signals being

transmitted in this frequency band are present in many locations as well.

31
Spectrum Analyzer

KI6-MON-2P4 Spectrum AnalyzerPJV-MON-IPa-H

-20 -r dBmiS <2

' 11 Kib n

,

1 l'

1

1 1 k1 . 1 ,

1 1 il j/l MU.aiLU;AWuU|_U~jU too

120 - MM MM [III MM MM MM MM MM MM MM

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency {2400,0 - 2500.0 MHz)

Attcnualion: dB

Dclcclion: RMS Average

CF: 2450.0 MHz SPAN: 100.00 MHz

RBW: 10 kHz VBW: 1 kHz

MaxHold: ON

Sid; Min Sweep Time: 1 .00 Milli Sec

Da(e; 08/06/2007 Time: 06:22:30 Model: MS271 ID Serial* 00421041

«g M1:-100.51 dBm(a2437.0MHz

'= P17 ; 30 ^

"

: ^0 :

-90 -E ;t

1

1,1 In Jill .1

1 .1 II 1 ^ 1 a\

Mill' Ml!

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500 MHz)

Aucnualion: dB

Detection: RMS Average

CF: 2450.0 MHz SPAN: 100.00 MHz

RBW: 10 kHz VBW: 3 kHz

Ma.xHold: ON

Sid: Min Sweep Time: 1 .00 Milli Sec

Dale: 08/06/2007 Time: 05:09:06 Model: MS271 ID SeriaU: 00421041

(a) (b)

Spectrum Analyzer

HI1-MON-2P4

-20- 11: .92.5 dBm/a —j= ' II H11

11

DO

00

1

1 f—

T U. ... i 1 ,. l» 1 , I 1

120- (III nil MM 1 1

1

1 1 1

1

1 1 1

1

1 1 II MM 1 1 1

1

MM

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400 - 2500 MHz)

AUcniialion; dB

Selection: RMS Average

CF: 2450.0 MHz SPAN: lOaOOMHz

RBW: 10 kHz VBW: 1 kHz

MaxHold: ON

Sid: Min Sweep Time: 1 .00 Mdli Sec

Dale: 08/06/2007 Time: 06:39:44 Model: MS2711D Serial tt- 00421041

Spectrum Analyzer

H09-MON-2P4

-20 -F

) dBiniS

1

' II H09 p

00

00

1

1 1,.. J , ,11 llti

120- MM MM MM J_UiL 1 1 1

1

1 1 1

1

MM MM III MM

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500.0 MHz)

Allenuadoni dB

Detection: RMS Average

CF: 2450.0 MHz SPAN: 100.00 MHz

RBW: 10 kHz VBW: 1 kHz

MaxHold: ON

Sid: Min Sweep Time: 1.00 Milli Sec

Dale: 08/06/2007 Time: 06:44:19 Model: MS2711D Serials: 00421041

(c) . (d)

Figure 4-6: A second set of handheld spectrum analyzer measurements collected over a

three-minute period in the 2.4 GHz frequency band in the engine plant. Again, signals are

clearly present in the three primary WLAN cinannels, as well as at other frequencies in the

band throughout the plant. The increased resolution in this set of graphs (10 kHz as opposed

to 30 kHz in Figure 4-5) provides a reduced noise floor for the measurement, but also

reduces the signal level in each measured frequency component, making the transient

signals appear as lower-level signals compared to those in Figure 4-5, when they are probably comparable in actuality.

We also carried out some longer-term studies in the assembly plant. Figure 4-7

shows a typical snapshot of the WLAN traffic at a fixed receiving site during production.

These data were collected over a 15-minute period during morning production on

August 3, 2006. These measurements were carried out with a directional antenna

aimed directly at one of the WLAN nodes. The 802.11b spectral mask has been drawn

over the signals for channels 1, 6, and 11 (center frequencies of 2.412, 2.437, and

2.462 GHz), showing the approximate level of each received signal. The spectral mask

simply shows the maximum allowed occupied bandwidth for 802.11b WLAN signals.

The lines show the allowed frequency span and the level to which signals need to be

attenuated outside the channel to prevent interference with neighboring channels.

32
spectrum Analyzer

M3

n fL ; in ^^- 09.47 dBm o 2400.0 MHM2: -109.47 dBm IS 2400.0 MH2M3; -109.47 dBm IS Z400.0 MHz 15 minute peak hold on -

1 1

1, i/F

fi m

kk Art h

M] 1

ll \ J i

.

J f ]) knf W ^n ^Ai \ ,

1 1 1

1

1 2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500.0 MHz)

CF: 2450.0 MH/. SPAN: 100.00 MHz Allcnualion: 10 dB RBW: 3 kHz VBW: 1 kHz Delcclion: Pos. Peak MaxHold: ON

Min Sweep Time: 50.00 Micro Sec

Date: 08/03/2006 Time: 06;41 ;08 Model: MS27 1 1

D

Serial #: 0042 1 04

1

Prcamp ON

Figure 4-7: Handheld spectrum analyzer measurements collected over a 15 minute period in the 2.4 GHz frequency band. The spectral mask for the three 802.11b WLAN channels used in the facility are indicated on the graph, with the approximate level superimposed over the

signals.

The high-level, spike-like signals seen in the channels adjacent to the center

channel may be caused by other narrowband, frequency-hopping equipment in the

vicinity such as a wireless scanning system used nearby. Also, the 802.11b protocol

uses "probe" signals that allow nodes on different channels to communicate with each

other. When examined over a long period, the probe signals show up as a set of

narrowband spikes in adjacent channels. These spikes have approximately the same

signal level as the main channel. Figure 4-8 shows three repeat measurements of a

typical 802.11b card made in isolation in a NIST anechoic chamber over a one-hour

period. The inset shows a single measurement, while the larger graph is the culmination

of several measurements. The probe signals emanating from the card are clearly

visible.

Finally, a comparison of received signal strength during production and during a break (Figure 4-9) at the assembly plant shows only slight changes in the level of

activity in the 2.4 GHz band.

33
P87: 5 min Intervals After 1 Hour

P87-5M-6

(^n -rMl: 57.06 dBm (5) 2420.0 MHz

1 1 1 1, -55- 1 —f 1 i1 ii

II 1 -fin- J. _j - 1 ,1 % 1

i'

; -65 -

-

1 _ —4' _ 4

-T** —

«=* -^r*y^Jh *«tU r T

jl IIImmmwiw L ^^ij mt^-

1 1 1 1 lilt 1 1 1 1 1 t t 1 Mil III MM 1 1 1 1 1 1 1 1 1 1 1 1

2320 2340 2360 2380 2400 2420 2440 2460 2480 2500 2520

Frequency (2320,0 - 2520.0 MHz)

CF: 2420.0 MHz SPAN: 200.00 MH/. Allcnualion: dB RBW: 100 kHz V13W: 30 kHz De(cclion: Pos. Peak MaxHold: ON

Min Sweep Time; 50.00 Micro See

Dale: 04/04/2005 Time: 14:48:13 Model: MS271 ID Serial #: 00421041

Figure 4-8: Handheld spectrum analyzer measurements of a representative 802.11b WLAN

card made in isolation over a one-hour period. Note the large, spike-like signals outside the

main channel which occur when the WLAN card monitors the environment for other cards in the area.

Spectrum Analyzer Spectrum Analyzer

MIO V -40-F HzMi - 4/2dB, ^243451 15 minute 1 50 peak hold on II

1 . -J hll L 1

1

1 Mmill

in . 1

n'^\ liftiLliI J"^ *i IV ''r 1 II f n 1" Jl \^ ^. w_JU

'

-140- 1 1 1 1 II 1 1 1 1

1

in, Ml> Mil MM

CF: 2450.0 MHz

RBW: 10 kHz

MaxHold: ON

Min Sweep Time: 50.00 Mi

Date: 08/03/2006 Model: MS27I1D

2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500,0 MHz) SPAN: 100.00 MHz

VBW: 3 kHz

- 08m p! ^^M^;- 8-24 08m ^2d3d^

15 minute peak hold on

Jl

1 1 L

1 ii MhW*^ ' W i

A. mi 1f 11 V mM

M

w^

r

P f\ h In f WPI III fii , rVfi"(Wli [^

- 1 1 1

1

1 1 1 1 MM 1 i-^t' 1 1 1 1

1

1 II

1

1 1 1

1

1 1 1

1

Mil 1111 -140 2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500

Frequency (2400.0 - 2500.0 MHz)

CF; 2450.0 MHz SPAN; 100.00 MHz .Mtcnualion; dB RBW; 10 kHz VBW; 3 kHz Detection; Pos. Peak

Ma.^Hold; ON

Min Sweep Time; 50.00 Micro Sec

Date: 08/032006 .Time: 08:28:44 Model; MS271 ID Serial /i; 00421041 Preamp ON

Figure 4-9: The left-hand graph shows activity in the 2.4 GHz band during production at the

assembly plant, while the right-hand graph shows activity during a break.

The detailed measurements of the spectrum in the 2.4 GHz frequency band

discussed here show that there is a significant level of activity in this band in all of the

plants. The use of an unlicensed portion of the spectrum for critical operations can be

problematic, since the activity level can be highly variable and so interference issues can arise intermittently. Personal electronics as well as other systems that operate in this band can interfere with operations. However, there are few licensed frequency

bands available for broadband data transfer in industrial environments. Frequency and

channel coordination, as is done at these facilities, are two good options to minimize

interference issues. A third would be to occasionally monitor activity, such as we have

done here. When the spectrum gets crowded or if interference issues arise, these types

of tests can be very beneficial in identifying and eliminating sources of interference.

34
5. Ultra-Wideband Propagation Measurements

5.1 Measurement set-up

In order to characterize the radio-wave scattering in these facilities, we deployed

a NIST-developed propagation measurement system. The system acquires both

magnitude and phase of signals covering a broad range of frequencies. The phases of

the sent and received signals are synchronized, enabling transformation of the recorded

signal into the time domain. Signals that cover a wide frequency band transform to short-duration pulses in the time domain. Thus, this system can be used to study the

effects of multiple reflections ('multipath') in an environment by measuring the time

taken for reflections of the initial pulse to decay below a certain threshold value.

The measurement system consists of a precision vector network analyzer (VNA),

a transmitting antenna, a receiving antenna, an 18 GHz analog optical link, and 50 Q

microwave cables to connect the antennas with the VNA, as shown in Figure 5-1. A

laptop computer is connected to the VNA in order to control the measurement process

and to acquire and store measured data. The VNA has a transmitter and receiver within

the same instrument and performs measurements between the two antennas. We

acquired both the magnitude and phase of the S-parameter S21, which describes the

characteristics of the transmission path. Data may be acquired at stepped frequencies over the range of 300 kHz to 18 GHz. For this series of tests, transmission data were

acquired at approximately 80,000 frequencies. For frequencies up to 1 GHz,

omnidirectional antennas were used. For frequencies from 1 GHz to 18 GHz, we used

directional dual-ridge waveguide antennas, similar to horn antennas. The transmitting

antenna was held fixed and the receiving antenna moved along aisles in the factory on

a rolling cart, as shown in Figures 5-2 through 5-8.

Receiving antenna

Transmitting

antenna

62 inchc

'200 m

Optical

Fiber

Figure 5-1: Ultrawideband, synthetic-pulse measurement system based on a vector network

analyzer. Frequency-domain measurements, synchronized by the optical fiber link, are transformed to the time domain in post-processing. This enables determination of wideband

path loss, time-delay spread and other figures of merit important in characterizing broadband

modulated signal transmission.

35
automobile

in production^ Assembly line

«v Assembly

line J^

C^C:)^ RX <^

Receive antenna

Transmit antenna \f

Fiber-optic cable

Transmitter stays

fixed while

receiver moves down aisle

Assembly line automobile

in production J

Figure 5-2: Layout of UWB tests in the assembly plant. The VNA (labeled "TX" for transmitter) remains in a fixed location. The signal received by the receive antenna (labeled

"RX" for receiver) is amplified and returned to the VNA via a fiber-optic cable that maintains

the phase relationships between measured frequency components. The receiver moves

away from the transmitter along a straight line in discrete steps.

110Am "-^-^^-^ 100 m 90 m

110Bm

Optical Fiber Link

80 m

75 m

50 m

40 m

20 m

10m

3m

m

Figure 5-3: Layout of the NIST ultrawideband tests in the stamping plant. The receive

antenna (RX) was placed on a rolling cart and moved along aisles H and G, as indicated on

the layout given in Figure 2-1. Measurements were taken at the distances indicated above.

The transmit antenna (TX) remain fixed. When directional antennas were used, at m,

50 m, 75 m, and 110 m, the RX antenna was rotated in the directions indicated above.

36
Figure 5-4: Photograph of the long corridor in the stamping plant where the UWB scattering

measurements were made. The low-frequency omnidirectional antennas are shown. The

VNA is located near the NIST staff at the left side of the photo.

Figure 5-5: Photograph looking the other way in the same corridor of the stamping plant.

The high-frequency directional antennas are shown. The photograph shows the VNA and the

optical fiber linking the transmitting and receiving antennas.

37
120Am I 100 m

'

1

120Bm

Optical Fiber Link

60 m

50 m

40 m

20 m

10m

6 m

3 m

m

Figure 5-6: Layout of the NIST ultrawideband scattering tests used in the engine plant. The

receive antenna (RX) was placed on a rolling cart and moved along aisles Q and P as

indicated on the layout given in Figure 2-2. Measurements were taken at the distances

indicated above. The transmit antenna (TX) remain fixed. When directional antennas were

used, at m, 50 m, and 120 m, the RX antenna was rotated in the directions indicated

above.

80 m

Figure 5-7: Corridor in the engine plant where UWB scattering measurements were made.

The receive antenna moved along the corridor on the rolling cart. The VNA and the

transmitting antenna were located behind the photographer.

38
Figure 5-8: VNA set-up in the engine plant. The directional transmit antenna is shown in the

foreground. The corridor shown in Figure 5-7 continues to the left side of this picture.

Note that throughout this work, measurement uncertainties are not reported. End

users of this data are primarily interested in large-scale statistical behavior on the order

of tens of decibels, thus including uncertainties on the order of 1 dB is of little value.

5.2 Frequency-domain measurements

We first looked at measurements of received signal levels in the frequency

domain. Figures 5-9 and 5-10 show measured excess path loss for the stamping plant

and engine plant, respectively, where the data have been normalized to the magnitude

of the direct-path received signal. The term "excess" means the direct-path signal has

been subtracted, so we are looking only at scattered signals. In cases where there is no

direct-path signal, we estimate its value by measuring free-space path loss for closely

spaced antennas at a known distance. Knowing the free-space path loss for a given set

of antennas and cables, we can then predict its value at other distances, since the freespace path loss has a 1/r dependence, where ris the distance in meters.

Figures 5-9 and 5-10 show results for frequencies from 1 GHz to 18 GHz at four

locations in the stamping plant and engine plant, respectively. All frequency

components were transmitted at the same amplitude level, but the received signals

show a range of amplitude values. The variations in received signal level across the

measured frequency span indicate that signals reflected (scattered) off metallic surfaces

and walls in the plants are interfering with the received signal. This is very pronounced

at the 50 m distances, where interference off of a major reflecting surface (a corridor in the stamping plant and a wall in the engine plant) occurs at the 50 m mark. Once the

receiving antennas turn the corner and are no longer within line of sight of the

transmitting antennas, the signal levels drop and become much more noisy. This is because the large number of reflected paths taken by the signals between transmitter

and receiver behave statistically like noise when there is no direct signal component.

We saw similar results for the low-frequency omnidirectional antennas. The complete

set of excess-path-loss data are given in the appendices at the end of the report.

39
20

10

-10 •

-20

-30

-40

-50

-60

-70 -80-

-90 -100-

-110 -120-

20

Stamping Plant DRG lo DRG — 10 m separation — System Noise (20 m)

4000 8000 12000 16000 20000

Stamping Plant DRG to DRG — 50 m separation System Noise (40 m)

Frequency (MHz)

12000 Frequency (MHz)16000 20000

(a) (b)

20

10

-10 H

-20

-30

-40

-50

-60

-70

-80

-90

-100 H

-110

-120

Stamping Plant DRG to DRG

80 m separation — System Noise (80 m)

4000 8000 12000

Freauencv (MHzl

16000

1 20000

(C)

Stamping Plant DRG to DRG — 110m separation (B) System Noise (80 m) n—'—I—'

\—

4000 8000 1 2000

Frequency (MHz)

\ 16000 20000

(d)

Figure 5-9: UWB measurements made at the stamping plant using directional antennas

facing each other at distances of (a) 10 m, (b) 50 m, (c) 80 m, and (d) 110 m. The deep nulls

in (b) indicate significant scattering. The low-level, noise-like signals in (c) and (d) mean that

interference and loss are creating a very noisy environment.

40
'fjM^l^m^^f/^/V'^r/Y^vw^

Engine Plant, DRG-DRG

10m Separation System Noise. 50m

^

I

I

I

^

I

^

I

r 2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Engine Plant, ORG-ORG

50m Separation System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

(a) (b)

Engine Plant, DRG-DRG

80m Separation System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

I

' ! 2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

(c) (d)

Figure 5-10: UWB measurements made at the engine plant using directional antennas

facing each other at distances of (a) 10 m, (b) 50 m, (c) 80 m, and (d) 120 m. The deep nulls

in (b) and (c) indicate significant scattering. The low-level, noise-like signals in (d) mean that

interference and loss are creating a very noisy environment.

5.3 Time-domain data

As mentioned above, the ability to acquire both magnitude and phase data over a

large number of frequencies makes it possible to perform post-processing where we

mathematically transform the stepped-frequency data into high-resolution, time-domain

waveforms. These, in turn, can be gated and filtered to isolate selected scattering

events. They can also be used to find wireless system figures of merit such as the

power delay profile of an environment, the K-factor, and RMS delay spread.

Post-processed time-domain waveforms that illustrate the multiple reflections

scattered by equipment and structures are shown in Figure 5-11. The initial waveform

41
event is the direct coupling between the transmit and receive antennas. The waveform

activity that follows corresponds to scattering from objects inside the plants. The

waveforms generally have exponentially decaying envelopes that are caused by lossy

materials inside the plants (e.g., manufactured products, machinery, concrete, etc.).

The fact that the plants exhibit such significant scattenng behavior can pose a

challenge for indoor wireless communications. One metric that is used to quantify this

effect is the RMS delay spread, which is the period required for the reflected signals to die down below a certain threshold level. RMS delay for the synthetic pulse

measurements is defined in [3]. A long RMS delay spread means that scattering is significant. When the RMS delay spread exceeds the error correction of the digital

modulation used in most wireless transmissions, errors in transmitted bits may occur. 0^

2 -120

I

' I' I'

I

'

I

'

I

'

100 200 300 400 500 600 700 Time (ns)

-200

Stamping Plant LowFreqDiscones

(6 m separation) Direct Component included No Direct Component (gate = 65 ns)

~1 :—'——'

'—I

1 300 600 900 1200 1500 1800 Frequency (MHz)

(a) (b)

<" -BOH

-120 -1

Engine Plant Low Freq Discones (6m sep)

Direct Component Included - No Direct Component (gate=74nS)

300 600 900 1200 Time (nS) (c)

Figure 5-11: Time-domain response for antenna-to-antenna separations of (a) 50 m in the

assembly plant; (b) 6 m in the stamping plant; (c) 6 m in the engine plant. Note the large

reflection from a truck loading door in the assembly plant measurement.

42
Post-processing of the measured VNA data readily yields the RMS delay spread.

Tables 5-1 and 5-2 give the RMS delay spread values that we measured in the

stamping plant and the engine plant, respectively, for both high-frequency and lowfrequency antennas.

Table 5-1:

Stamping plant

Low-frequency, omnidirectional

Table 5-2:

Stamping plant

High-frequency, directional antennas

Position

(m)

RMS Delay

Spread (ns)

Mean Delay

(ns)

6* 61 34

10* 76 50

20* 103 73

40* 117 72

50* 173 118

60* 142 117

75* 139 101

80 128 107

90 130 136

100 146 173

110A 153 220

110B 153 218

Position

(m)

RMS Delay

Spread (ns)

Mean

Delay (ns)

6* 62 19

10* 90 49

20* 75 30

40* 64 22

50* 75 33

60* 78 36

75* 79 37

80 106 97

90 97 88

100 104 117

110A 116 153

110B 131 158

110B

elevated

128 165

* The positions with an asterisk indicate calculations where the direct component has been

removed and the RIVIS delay spread calculated to a stop time of 900 ns, where the signal

levels are approximately 20 - 40 dB above the noise floor of the instrument.

If we further post-process the results, we can find the resulting reverberant cavity

quality factor Q. Cavity Q is one metric that is indicative of complex cavity behavior: the

higher the Q, the more reverberant the cavity and the longer the decay time. Q is defined as

Q^lKTf, (5-1)

where i is the received-power decay time, and f\s the center frequency of interest. The

rate of decay is defined as the time it takes for the signal to decay to 37 % of its initial value.

43
Table 5-3:

Engine plant

Low-frequency, omnidirectional

Position

(m)

RMS Delay

Spread (ns)

Mean

Delay (ns)

10* 66 36

20* 61 38

40* 107 77

50* 105 75

60* 116 93

80* 112 82

100 129 185

120A 133 208

120B 142 145

Table 5-4:

Engine plant

High-frequency, directional antennas

Position

(m)

RMS Delay

Spread (ns)

Mean

Delay (ns)

6* 16 2

10* 29 4

20* 40 9

40* 51 11

50* 53 11

60* 57 13

80* 58 13

100 115 141

120A 114 155

120B 120 157

* The positions with an asterisk indicate calculations where the direct component has been

removed and the RMS delay spread calculated to a stop time of 900 ns, where the signal

levels are approximately 20 - 40 dB above the noise floor of the instrument.

Figure 5-12 depicts the decay characteristics in the assembly plant for

frequencies in the vicinity of 950 MHz, 2.45 GHz, and 5.2 GHz. The decay times vary

from 127 ns to 170 ns, with Q values covering a range of 1015 to 4149. This high-Q,

reverberant behavior results primarily from the all-metal enclosure of the building and

exhibits characteristics similar to some laboratory-based reverberation chambers.

A reverberant environment, such as this, produces much scattering in addition to the direct path between a transmitter and receiver and inhibits the ability to communicate. One metric used to quantify this effect is the K-factor, which is the ratio of

the energy in the direct-path coupling between the transmit and receive antennas to the

energy that results from environmental reflections. A high K-factor means that the

antenna-to-antenna coupling dominates, and a low K-factor implies a strongly

reverberant (high multipath) environment.

^

44
80 120 Time (ns)

Figure 5-12: Time-domain response for a 50 m antenna separation in the assembly plant

using an omnidirectional transmit antenna. Decay characteristics are shown at selected

wireless frequencies using a 200 MHz averaging bandwidth.

We post-processed the VNA data to find the K-factor of the assembly plant.

Figure 5-13 (a) and (b) depict K-factors measured in the assembly plant as function of

antenna separation from 2m- 300 m. We used both directional (Figure 5-1 3(a)) and

omnidirectional (Figure 5-1 3(b)) transmit antennas. The curves are smoothed out by

use of frequency averaging over a bandwidth of 200 MHz. Results are plotted in decibels for the 950 MHz, 2.45 GHz, and 5.2 GHz wireless bands.

For the case of the directional transmit antenna (Figure 5-1 3(a)), the K-factor

increases significantly for antenna separations less than 20 m. A more rapid increase is noted at the higher frequencies due to the higher gain of the transmit antenna and

improved directionality. As the antenna separation is increased beyond 20 m, the Kfactor generally stays in the vicinity of unity (0 dB). We note a peak in the 5.2 GHz data

at 150 m, which might be due to a combination of antenna pattern effects and a strongly

reflecting path between transmitter and receiver. A similar effect is seen for the

950 MHz data.

45
k-Faclor DRH

Anlcnnos950 MHz

2450 MHz

5200 MHz

k-Fatlor Discone

Anicnnas950 MHz

2450 MHz

5200 MHz

10 100 Distance (m)

n I 10 100 Distance (m)

(a) (b)

Figure 5-13: K-factor over a 200 MHz bandwidth as a function of distance in the assembly

plant for three different center frequencies. Black: 950 MHz, Red: 2.45 GHz, Green: 5.2 GHz.

(a) Directional antennas, (b) Omnidirectional antennas.

The situation changes when the transnnit antenna is omnidirectional, as shown in Figure 5-1 3(b). The K-factor now drops to unity or less (< dB) as distance is increased

beyond 5 m. At a distance of 100 m or more, some peaks in the K-factor occur. This is probably due to a combination of the effects of the antenna pattern and the occurrence

of strong environmental scattering. Lower values of K-factor indicate that the

reverberant behavior of the assembly plant is much stronger if we illuminate it with an

omnidirectional antenna. We "also see that the use of a directional antenna reduces the

effects of scattering and multipath for transmitter/receiver separations of 20 m or less.

For larger separations, however, the advantages of using a directional antenna diminish

rapidly.

Figures 5-14 (a) through (d) depict the K-factor as a function of frequency for

both the directional and non-directional antenna types. Each curve corresponds to a

different transmit/receive antenna separation. Results are plotted over a frequency

range from 1 GHz to 10 GHz using an averaging bandwidth of 200 MHz.

46
1 '

\

' r

4000 6000 8000 10000 Frequency (MHz)

^1 '

I

' r~

2000 3000 4000 Frequency (MHz)

5000 6000

(a) (b)

4000 6000 8000 Frequency (MHz)

~i

'

\ ' I

' r~

2000 .1000 4000 5000 Frequency (MHz)

(c)' (d)

Figure 5-14: K-factor as a function of frequency for various antenna spacings in the

assembly plant, (a) Directional antennas (5 m to100 m). (b) Omnidirectional antennas (2 m to 50 m). (c) Directional Antennas (150 m to 300 m). (d) Omnidirectional antennas (100 m to 300 m). Averaging bandwidth was 200 MHz.

In Figures 5-1 4(a) and 5-1 4(c), we see rapid variations in received-signal level as

a function of frequency for the directional antennas. These variations are caused by the

more connplex pattern characteristics of the directional antennas. Peak-to-peak

variations are typically in the range of 15 dB to 20 dB. The corresponding results for an

omnidirectional transmit antenna, shown in Figures 5-14(b) and 5-14(d), exhibit

smoother variations with frequency, due to the simple pattern characteristics. Peak-topeak variations in the K-factor of 5 dB tolO dB are typically seen as a function of

frequency. The effects of using different types of antennas on received signal levels can

be seen in more detail in the appendices, where the complete set of excess-path-loss

data is given.

47
5.4 Conclusion

The three buildings studied here exhibit complicated scattering and multipath

propagation as functions of both distance and frequency. These characteristics are due

to a combination of metallic walls and ceilings, concrete floors, and a multitude of

metallic scatterers inside the plants.

One example of the complicated nature of radio-wave propagation in these

facilities is well illustrated by the interference patterns seen in the UWB measurements

of Figures 5-9 and 5-10. The signals emitted from our antennas were constrained to propagate down the aisleways by the antennas that we used and by the metallic

structures on either side of the aisle. Very little energy was transmitted up and over the

structures lining the aisles. Thus, under line-of-sight conditions, signals sometimes

experienced deep interference nulls when the receiver was located midway between the

transmitter and a reflecting surface such as a wall or even a perpendicular corridor, as shown in Figures 5-9(b) and 5-1 0(b). When the receiver was located around the corner from the transmitter, radio-wave penetration through the metallic structures in the plants

was not possible. As a result, in non-line-of-sight conditions, signals were attenuated

and exhibited classical, noise-lil<e, Rayleigh-distributed behavior.

The UWB measurements also showed that the use of directional antennas

reduced the RMS delay spread. We saw this in the stamping and engine plants, the

only two facilities where we calculated RMS delay spread. The RMS delay spread in the

engine plant was significantly longer than that of the stamping plant, highlighting the

more open floor plan in the engine plant. Reflections take longer to die out in this

environment. When delay spread becomes long enough, it can interfere with the error correction in the transmission and additional errors can occur. The impact on wireless communications will depend on the type of system, data

rate, and the location of the transmitter(s) and receiver(s). The "representative

measurements provided here of excess path loss, RMS delay spread, and K-factor are

useful parameters that we hope will guide the design of wireless communications

systems in these types of plants.

6. Summary

Our background ambient measurements offered a few surprises. While they

showed expected significant transmission activity in the 2.4 GHz unlicensed ISM

frequency bands, there was essentially no activity in the 5.8 GHz band at the engine

plant, and little in the 900 MHz frequency band in either plant. As expected, we saw

transmissions from external sources such as broadcast stations and cellular telephone

traffic. Since these are in frequency bands outside the operational bands of interest,

they do not currently cause interference to operations. Finally, we saw some

unintentionally generated machine noise at low frequencies within the stamping plant.

This unintentionally transmitted noise can affect systems that operate at lower

frequencies, such as diagnostics used in automotive applications.

The site-specific spectrum analyzer measurement results showed that wireless

transmissions in the 2.4 GHz frequency band can be detected at most locations

throughout these two facilities. This indicates that transmitting and repeating nodes

have been successfully installed throughout the plants.

48
UWB scattering measurements show that these facilities are highly reflective,

reverberant environments that can complicate reliable performance of wireless

technology. While the existing wireless technology has been successfully deployed,

future expanded use of wireless for control and telemetry operations could pose an

interference problem if the environment is not considered.

There are several methods that can be implemented to minimize the effects of

the reflective environment. Some are operational in nature, some deal with changing the

environment, and some are technology based. Examples of these methods include:

Operational

• Use licensed frequency bands where possible

• Coordinate frequency and channel usage

• Restrict or forbid use of personal electronics in key frequency bands (e.g.,

2.4 GHz band)

Environmental

• Install absorbing material in the proximity of local wireless systems such as

controllers

• Place additional nodes at key locations

Technological

• Use wireless systems having high immunity to electromagnetic interference

• Use wireless systems designed to operate in high multipath environments

• Employ equipment on the production floor that emit little machine noise

• Use directional antennas where appropriate

The results of this and the prior study at the assembly plant will be used to generate improved statistical models that describe the RF nature of the production floor

for wireless systems. These models may be used by telecommunications manufacturers

to engineer more robust designs for communications equipment, as well as for

development of improved standards specifically for the automotive industry.

Also, based on the measured results from the three automotive plants we have

tested, work is currently underway at NIST to develop laboratory-based test methods to prequalify wireless devices for deployment on the factory floor. The test methods are based on measuring a device's functionality when placed in a reverberation chamber

whose characteristics have been tuned to simulate those of the factory floor. If a device

operates properly in the test chamber, engineers can be confident that it would operate

on the factory floor as well.

Partial funding and support for this work was provided by the NIST United States

Council for Automotive Research (USCAR) Liaison Dr. John Slotwinski, NIST

Manufacturing Engineering Laboratory, National Institute of Standards and Technology,

Gaithersburg, MD 20899-8200.

49
7. References

[1] IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)

Specifications: Higher-Speed Physical Layer Extension in the 2.4 GHz Band, IEEE

Standard 802. 11 bTM-1 999.

[2] IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)

Specifications: High-Speed Physical Layer in the 5 GHz Band, IEEE Standard 802.11aTM-

1999.

[3] K.A. Remley, G. Koepke, C.L. Holloway, C. Grosvenor, D. Camell, J. Ladbury, D. Novotny,

W.F. Young, G. Hough, M.D. McKinley, Y. Becquet, J. Korsnes, "Measurements to Support

Broadband Modulated-Signal Radio Transmissions for the Public-Safety Sector," Natl. Inst. Stand. Technol. Note 1546, Apr. 2008.

50
Appendix A: Assembly Plant, Low-Frequency Data,

Omnidirectional Transmit and Receive Antennas

The following pages contain the complete set of measured data from the assembly plant

covering a frequency range of 100 MHz to 1.2 GHz when omnidirectional transmit and

receive antennas were used.

51
Assembly Plant: Omnidirectional antennas

20

en

ca a.uo

-20 -

-40

-60-

-80

-100-

-120

^; i: ^ \iHri^M

''

. i^

'pf I

y^fv^,f^^'

Assembly Plant - Diamond Discones

5 m separation

System Noise (300m)

200 400 600 800 1000 1200 1400

Frequency (MHz)

20

telWli/lrt

o

a.

X

120

Assembly Plant - Diamond Discones 10m separation

System Noise (300m)

200 400 600 800 1000 1200 1400

Frequency (MHz)

Figure A.1: Excess path loss from 100 MHz to 1.2 GHz in the assembly plant. Top: 5

m separation. Bottom: 10 m separation.

52
Assembly Plant: Omnidirectional antennas

T3

-J

Cu

o

Assembly Plant - Diamond Discones 20 m separation

System Noise (300m)

1 1 r 200 400 600 800 1000 1200 1400

Frequency (MHz)

20

a

o

-J

U

X

-20

-40

-60

-80

100

-120

Assembly Plant - Diamond Discones 50 m separation

System Noise (300m)

U, \\

,!i l\Wh\ wiimm

200 400 600 800 1000 1200 1400

Frequency (MHz)

Figure A.2: Excess path loss from 100 MHz to 1.2 GHz in the assembly plant. Top:

20 m separation. Bottom: 50 m separation.

53
Assembly Plant: Omnidirectional antennas

Assembly Plant - Diamond Discones

75 m separation — System Noise (300m)

CQ-a

a.

4Jo

X

200 400 600 800 1000 1200 1400

Frequency (MHz)

20

Assembly Plant - Diamond Discones

1 00 m separation

System Noise (300m)

CQ-a

I

^'

- w

120

200 400 600 800 1000 1200 1400

Frequency (MHz)

Figure A.3: Excess path loss from 100 MHz to 1.2 GHz in the assembly plant. Top:

75 m separation. Bottom: 100 m separation.

54
Assembly Plant: Omnidirectional antennas

20^

-20

-a

S -40

-J.a

-60

-80

-100

-120

Assembly Plant - Diamond Discones

125 m separation

System Noise (300m)

200 400 600 800 1000 1200 1400

Frequency (MHz)

Assembly Plant - Diamond Discones

150 m separation

System Noise (300m)

1 r 200 400 600 800 1000 1200 1400

Frequency (MHz)

Figure A.4: Excess path loss from 100 MHz to 1.2 GHz in the assembly plant. Top:

125 m separation. Bottom: 150 m separation.

55
Assembly Plant: Omnidirectional antennas

20

Assembly Plant - Diamond Discones

1 75 m separation

System Noise (300m)

03-a

o

X

-20 -

-40 -

-60

-80

-100

120 1 ^

\ '\

^ \

'

\

^

\

^

\

^

I 200 400 600 800 1000 1200 1400

Frequency (MHz)

20

1

Assembly Plant - Diamond Discones 200 m separation

System Noise (300m)

o

-J

C3

200 400 600 800 1000 1200 1400

Frequency (MHz)

Figure A.5: Excess path loss from 100 MHz to 1.2 GHz in the assembly plant. Top:

175 m separation. Bottom: 200 m separation.

56
Assembly Plant: Omnidirectional antennas

20

Assembly Plant - Diamond Discones 225 m separation

System Noise (300m)

200 400 600 800 1000

Frequency (MHz)

1200 1400

20

-20 ^

S -40

-J

a.

o

X

-60

-80

100

-120

Assembly Plant - Diamond Discones 250 m separation

System Noise (300m)

200 400 600 800 1000

Frequency (MHz)

1200 1400

Figure A.6: Excess path loss from 100 MHz to 1.2 GHz in the assembly plant. Top:

225 m separation. Bottom: 250 m separation.

57
Assembly Plant: Omnidirectional antennas

20

03-a

Ohu

o

X

-20

-40

-60

-80 "

-100

120

Assembly Plant - Diamond Discones 275 m separation

System Noise (300m)

200 400 600 800 1000 1200 1400

Frequency (MHz)

20

Assembly Plant - Diamond Discones 300 m separation

System Noise (300m)

200 400 600 800 1000 1200 1400

Frequency (MHz)

Figure A.7: Excess path loss from 100 MHz to 1.2 GHz in the assembly plant. Top:

275 m separation. Bottom: 300 m separation.

58
Appendix B: Assembly Plant, High-Frequency Data,

Directional Transmit, Omnidirectional Receive Antennas

The following pages contain the complete set of measured data from the assembly plant

covering a frequency range of 1 GHz to 12 GHz when directional transmit and

omnidirectional receive antennas were used.

59
Assembly Plant: Directional transmit, omnidirectional receive antennas

40

CQ

•T3

O

-JS -40

C3 Oh

4)O

X

-80 -

-120

Assembly Plant - DRG to Tophat

5 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

o

o

X

40

^ -40

-80

120

Assembly Plant - DRG to Tophat

10 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure B.1: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top: 5 m

separation. Bottom: 10 m separation.

60
Assembly Plant: Directional transmit, omnidirectional receive antennas

40

CQ

o

-J^ -40

AhU

om

-80

-120

Assembly Plant - DRG to Tophat 20 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

40 -

o

-J£ -40

C3

X

-80

-120

Assembly Plant - DRG to Tophat

50 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure B.2: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

20 m separation. Bottom; 50 m separation.

61
Assembly Plant: Directional transmit, omnidirectional receive antennas

40 -n

-o

6 -40

a.

X

-80 -J

Assembly Plant - DRG to Tophat

1 00 m separation

System Noise (300m)

-120

4000 8000

Frequency (MHz)

12000

73

Oh

o

XW

40

e -40 -

-80-

Assembly Plant - DRG to Tophat

125 m separation

System Noise {300m)

120 4000 8000

Frequency (MHz)

12000

Figure B.3: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

100 m separation. Bottom: 125 m separation.

62
Assembly Plant: Directional transmit, omnidirectional receive antennas

40

QQ

o

-Ja

Ohu

u

X

^ -40

-80

-120

Assembly Plant - DRG to Tophat

150 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

40

S -40 a

o

X

-80 ^

-120

Assembly Plant - DRG to Tophat

175 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure B.4: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

150 m separation. Bottom: 175 m separation.

63
Assembly Plant: Directional transmit, omnidirectional receive antennas

40 -

S -40

U

-80

-120

Assembly Plant - DRG to Tophat 200 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

40

-a

3 -40

OhU

o

X

-80

-120

Assembly Plant - DRG to Tophat

225 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure B.5: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

200 m separation. Bottom: 225 m separation.

64 I
Assembly Plant: Directional transmit, omnidirectional receive antennas

40

T3

O

-J:S -40-

CL,

u

ix:

-80-

-120

Assembly Plant - DRG to Tophat 250 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

o

-J

u

XW

40

5 -40

-80

Assembly Plant - DRG to Tophat 275 m separation

System Noise (300m)

-120

4000 8000

Frequency (MHz)

12000

Figure B.6: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top;

250 m separation. Bottom: 275 m separation.

65
Assembly Plant: Directional transmit, omnidirectional receive antennas

40

PQ

o

-J:S -40

as a.

-80

-120

Assembly Plant - DRG to Tophat 300 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure B.7: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

300 m separation.

66

L.
Appendix C: Assembly Plant, High-Frequency Data,

Directional Transmit and Receive Antennas

The following pages contain the complete set of measured data from the assembly plant

covering a frequency range of 1 GHz to 12 GHz when directional transmit and receive

antennas were used.

67
Assembly Plant: Directional transmit and receive antennas

20

-_^v>V'S>^'-V*Y-*\,'"iA->''

CQ-o

o

-J

Oh

o

X

-20

-40

-60

-80

100

120

Asjsembly Plant - DRG to DRG

5 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

20

-20 S

S -40

-J

a,

<L> O

-60

-80

-100

-120

mnf\ ,V^>^/\'Vy'^-^^^V<yVvj

Assembly Plant - DRG to DRG

' 1 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure C.1: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top: 5 m

separation. Bottom: 10 m separation.

68

\
Assembly Plant: Directional transmit and receive antennas

20

iWf^vw'wfyY^

-20

CQ-o

S -40

Q. -60-1

-80 -

100

-120

Assembly Plant - DRG to DRG

20 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

20

0^ i^jfH/^>i

s

o

03

o

-20

-40

-60

-80

100

120

Asjsembly Plant - DRG to DRG

50 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure C.2: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

20 m separation. Bottom: 50 m separation.

69
Assembly Plant: Directional transmit and receive antennas

20

-o

o

ess

u

o

-20

-40

-60

'^yi/*''*^i

-80^

-100

120

Assembly Plant - DRG to DRG

1 00 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

20

-20

T3

ooo -40

a.

4)O

X

-60

-80

-100

-120

^^^v-Zy^'W^ ^^^Y^^^

Assembly Plant - DRG to DRG

1 25 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure C.3: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

100 m separation. Bottom: 125 m separation.

70
Assembly Plant: Directional transmit and receive antennas

20

-20-

CQ-o

S -40

cu

o

-60

-80

-100

120

Assembly Plant - DRG to DRG

150 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

20 -I

-20

S -40

-J

X

-60

-80

-100

-120

/Vf^'^'^'^^'^'^v^'^yrti*'^

Assembly Plant - DRG to DRG

175 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure C.4: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top;

150 m separation. Bottom: 175 m separation.

71
Assembly Plant: Directional transmit and receive antennas

20

^^^.^^^^v-wv-vv-^'X*^,^ ,W

•a

IXu

X

IJLI

-20

-40

-60

-80

-100

-120

Assembly Plant - DRG to DRG

^ 200 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

20

-20

S -40

^ -60 uo

XW

-80

100

-120

^^^^y^^A/^Y^'

Assembly Plant - DRG to DRG

225 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure C.5: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

200 m separation. Bottom: 225 m separation.

72
Assembly Plant: Directional transmit and receive antennas

20

CQa

03 Oh

0)o

X

-20

-40-

-60

-80 -

-100

-120

.^/^/^'''''^^''^ym

Assembly Plant - DRG to DRG

250 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

20

-20

S -40

cu

o

-60

-80

-100

-120

^^^>,^^,^,^^,

Assembly Plant - DRG to DRG

275 m separation

System Noise (300m)

4000 8000

Frequency (MHz)

12000

Figure C.6: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

250 m separation. Bottom: 275 m separation.

73
Assembly Plant: Directional transmit and receive antennas

20

-20

T3

S -40

-J

x:

-60

-80

-100

-120

i

Assembly P'^nt - nRr. to npr. 300m separation

System Noise (JUUm)

4000 8000

Frequency (MHz)

12000

Figure C.7: Excess path loss from 1 GHz to 12 GHz in the assembly plant. Top:

300 m separation.

74
Assembly Plant: Directional transmit and receive antennas

20 -n

CQT3

o

X

pq

-20

-40

-60

-80

100

-120

Assembly Plant - DRG to DRG

50 m separation - boresight 50 m separation - 458 - 08 clock position 50 m separation - 458 - 908 clock position 50 m separation - 458 - 1 808 clock position 50 m separation - 458 - 2708 clock position

4000 8000

Frequency (MHz)

12000

CQ

o

X

20 -1

-80

-100

-120

Assembly Plant - DRG to DRG

100 m separation - boresight 100 m separation - 458 - 08 clock position 100 m separation - 458 - 908 clock position 100 m separation - 458 - 1808 clock position 100 m separation - 458 - 2708 clock position

4000 8000

Frequency (MHz)

12000

Figure C.8: Excess path loss from 1 GHz to 12 GHz in the assembly plant when the

receive antenna is rotated through angles from zero (boresight) to 270° as defined in Figure 5-3 for the stamping plant. Top: 50 m separation. Bottom: 100 m separation.

75
Assembly Plant: Directional transmit and receive antennas

-a

o

ow

-80

-100

-120

Assembly Plant - DRG to DRG — 300 m separation - boresight — 300 m separation - 458 - 08 clock position 300 m separation - 458 - 908 clock position 300 m separation - 458 - 1 808 clock position 300 m separation - 458 - 2708 clock position

4000 8000

Frequency (MHz)

12000

I

Figure C.9: Excess path loss from 1 GHz to 12 GHz in the assembly plant when the

receive antenna is rotated through angles from zero (boresight) to 270° as defined in Figure 5-3 for the stamping plant. Top: 300 m separation.

76

i
Appendix D: Stamping Plant, Low-Frequency Data,

Omnidirectional Transmit and Receive Antennas

The following pages contain tine complete set of measured data from the stamping plant

covering a frequency range of 100 MHz to 1.2 GHz when omnidirectional transmit and

receive antennas were used.

71
Metal Stamping Plant: Omnidirectional antennas

20 n

o

o

o

,1

.1

11

1

j

|rh,| '*

nil 'ft -20 -1

' 1

1 1 -30 n 1 1

t/3 o -40^

6 -50 -

CL,« -60-

\i kl

i A.

If

^ -70-

W -J -80-

ill, 1 ,'' I'li

i

-90 - ' 1li

1 M

'

1 - Stamping Plant -100- Diamond to Diamond

-

1 m separation

-110

1 -^n System Noise (20 m)

-120 ' 1

' ! ' 1 500 1000 1500

Frequency (MHz)

20 -\ /I k i

o

o

o

11

,1

<1

<

1 Miii'^'

r hi

1 -20 H II 1 -30-

1/3 S -40-

-J:S -50- ^ -60 -

^ -70 ~i w

1 1 ) 'i 1

' if

-80- ill '

i

;

i 1'

' II -90- 'i Stamping Plant -100- Diamond to Diamond

-110-

20 m separation

System Noise (20 m)

-120 '1^1 ' 1 500 1000 1500

Frequency (MHz)

Figure D.1: Excess path loss from 100 MHz to 1.2 GHz in the stamping plant. Top:

10 m separation. Bottom: 20 m separation.

78
Metal Stamping Plant: Omnidirectional antennas

20q :, , ,1 10 H

0-

-10 H ^

1 f

1

1 ft

-20 -lb'

1 -30 i

M

!

\ 1

i -40 - j

^ -70

-80 - r#'''

ill

II

1

1 i|ii.

tif'i^i

1

1'

1'

-90-

-100-

-110-

Stamping Plant Diamond to Diamond

40 m separation

System Noise (20 m)

1 on -IzU

1 ' 1

'

1 500 1000 1500

Frequency (MHz)

20 -n „

,i

10 1

-10 -i 'j! I'i

1*

1

I

It

-20 -

1 3 -30 ^

! 'ij

' !

i -40 - ,1 1

'^^ ~

1 1

I. 11 111 im ilal.) \'ki if

% -60 -

III

-80^ ' m

t|1''1'

1

1'

iV rff'J },l'^ !

j

-90-

-100-

If 1

,

1 Stai Diamo

nping Plant nd to Diamond m separation

jystem Noise (20 m) -110 - c

-izu I'^n

1

'

1

' 1 500 1000 1500

Frequency (MHz)

Figure D.2: Excess path loss from 100 MHz to 1.2 GHz in the stamping plant. Top:

40 m separation. Bottom: 50 m separation.

79
Metal Stamping Plant: Omnidirectional antennas

OJ

Id Oh

(Uu

20 -n

10OH

-10

-20 H

-30

-40

-50 H

-60

-70

-80

-90

-100

-110

-120

! i

I J' !*

r\^^

"^

M

Ik. I

'ill % i

^ ^'^^^l%ift:^iy|''

81

Stamping Plant Diamond to Diamond

60 m separation

System Noise (60 m)

500 1000

Frequency (MHz)

1500

20

10

-10

-20 H

T3 -30

, .,rii)A r\ "

o

-J

Q4>O

X

-40

-50

-60 -

-70 -

-80

-90 ^

-100

-110

-120

- ^'K^.

^' V ffllJ, :,,i

'in 'I I

Stamping Plant Diamond to Diamond

75 m separation

System Noise (60 m)

500 1000

Frequency (MHz)

1500

Figure D.3: Excess path loss from 100 MHz to 1.2 GHz in the stamping plant. Top:

60 m separation. Bottom: 75 m separation.

80
Metal Stamping Plant: Omnidirectional antennas

20 -1

10

-10 H

-20 ^ -30

S -40

-J^ -50

C3 Oh« -60

^ -70 H

-80

-90

-100

-110

-120

,ii.J'i:

i

li jt...*;U /:'* l,S:!i/ Fi,i;i

\ /V1^

^'"-i'P

Stamping Plant Diamond to Diamond

80 m separation

System Noise (60 m)

500 1000

Frequency (MHz)

1500

Stamping Plant Diamond to Diamond — 100 m separation

System Noise (1 10m, A)

500 1000

Frequency (MHz)

1500

Figure D.4: Excess path loss from 100 MHz to 1.2 GHz in the stamping plant. Top:

80 m separation. Bottom: 100 m separation.

81
Metal Stamping Plant: Omnidirectional antennas

CQ-o

o

o

X

Stamping Plant Diamond to Diamond

110 m separation (A)

System Noise ( 1 1 Om, A)

500 1000

Frequency (MHz)

1500

Stamping Plant Diamond to Diamond

110 m separation (B) System Noise (1 10m, A)

1 m separation (B) - repeat measurement

500 1000

Frequency (MHz)

1500

Figure D.5: Excess path loss from 100 MHz to 1.2 GHz in the stamping plant. Top:

110 m separation, straight path. Bottom: 110 m separation, around corner. See

Figure 5.3

82
Appendix E: Metal Stamping Plant, High-Frequency Data,

Directional Transmit, Omnidirectional Receive Antennas

The following pages contain the complete set of measured data from the metal

stamping plant covering a frequency range of 1 GHz to 12 GHz when directional

transmit and omnidirectional receive antennas were used.

83
stamping Plant: Directional transmit, omnidirectional receive antennas

T3

O

-J

Cu

X

20

10

-10

-20

-30 H

-40

-50

-60 H

-70

-80

-90

-100

-110

-120

Stamping Plant DRG to ARA (Tophat) 10 m separation

System Noise (20 m)

4000 8000 12000

Frequency (MHz)

16000 20000

CQ

O

C3 Cu

o

X

20

10

-10

-20 H

-30

-40 S -50 -

-60 -

-70

-80 H

-90

-100

-110

-120

Stamping Plant DRG to ARA (Tophat) 20 m separation

System Noise (20 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure E.1: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 10 m

separation. Bottom: 20 m separation.

84
stamping Plant: Directional transmit, omnidirectional receive antennas

20

10

-10

-20

^—

s

-o -30

C/1 V2o -40

_1^ -50 «

cuM -60

«1

(Uo

-70

LU -80

-90 -

-100 -

-110

-120

Stamping Plant DRGto ARA(Tophat)

40 m separation

System Noise (40 m)

4000 8000 12000

Frequency (MHz)

16000 20000

03

O

20

10

-10

-20

-30

-40 ^ -50

Oh

O

-60 H

-70

-80

-90

-100

-110

-120

Stamping Plant DRG to ARA (Tophat) 50 m separation

System Noise (40 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure E.2: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 40 m

separation. Bottom: 50 m separation.

85
stamping Plant: Directional transmit, omnidirectional receive antennas

20

10

-10 H

-20

-30

-40

-50 -

-60-

-70

-80 -\

-90

-100

-110

-120

03-a

o

-J

CL.

<1> o

Xw

Stamping Plant DRG to ARA (Tophat) 60 m separation

System Noise (40 m)

'

\

^

\

^

\ 4000 8000 12000

Frequency (MHz)

16000 20000

C3

20

10

-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

-110

-120

Stamping Plant DRG to ARA (Tophat) 75 m separation

System Noise (40 m)

75 m separation-repeat measurement

4000 8000 12000

Frequency (MHz)

16000 20000

Figure E.3: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 60 m

separation. Bottom: 75 m separation.

86
stamping Plant: Directional transmit, omnidirectional receive antennas

20

10 -

-10-

-20

-30

-40

-50 H

-60

-70

-80

-90 H

-100

-110

-120

03-a

o

-J

Oh

o

X

Stamping Plant DRGto ARA(Tophat)

80 m separation

System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

CQ-a

o

-J

X

20

10OH

-10

-20

-30 H

-40

-50

-60

-70 -

-80 -

-90 100

110

120

Stamping Plant DRG to ARA (Tophat) 90 m separation

System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure E.4: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 80 m

separation. Bottom: 90 m separation.

87
stamping Plant: Directional transmit, omnidirectional receive antennas

o

03

4)O

X

20

10 H

-10

-20

-30

-40 ^ -50

-60

-70

-80

-90

-100

-110

-120

Stamping Plant DRG to ARA (Tophat) 100 m separation

System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

CD-a

C3 0-

O

Stamping Plant DRG to ARA (Tophat) 110 m separation (B) 110 m separation (A)

System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure E.5: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 100

m separation. Bottom; 110 m separation, see Figure 5-3.

88
Appendix F: Metal Stamping Plant, High-Frequency Data,

Directional Transmit and Receive Antennas

The following pages contain the complete set of measured data from the metal

stamping plant covering a frequency range of 1 GHz to 12 GHz when directional

transmit and receive antennas were used.

89
22

a.

y.

W

Stamping Plant: Directional transmit, receive antennas

20-1

10

0-J

-10

-20

-30

-40 ^

-50 -

-60 -

-70 -

-80 -

-90 H

-100

-110

-120

Stamping Plant DRG to^DRG — 6m separation

System Noise (20 m)

4000 8000 12000

Frequency (MHz)

16000 20000

o

-J

Xm

20

10

-10

-20

-30

-40

-50

-60

-70

-80

-90

100

110

120

Y/V''*''Vv-^-'

Stamping Plant DRG to^DRG — 10 m separation — Svstem Noise (20 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure F.1: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 6 m

separation. Bottom: 10 m separation.

90
W|V/¥Yv''^A"A'^i;Vf\/r''^'^

Stamping Plant: Directional transmit, receive antennas

20 ^

10

-10

-20 3 "30 —

S -40

-J5 -50

Cu« -60

^ -70

-80

-90

-100

-110

-120

Stamping Plant DRG to DRG

20 m separation

System Noise (20 m)

4000 8000 12000

Frequency (MHz)

16000 20000

20

10

-10

-20

-30

-40

-50

-60

-70

-80 H

-90

-100

-110

-120

Stamping Plant DRG to DRG — 40 m separation — System Noise (40 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure F.2: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 20 m

separation. Bottom: 40 m separation.

91
stamping Plant: Directional transmit, receive antennas

20

10

-10

-20

0373

O

P3 0.

X

-30

-40 S -50

-60

-70

-80

-90

-100

-110

-120

Stamping Plant DRG to DRG — 50 m separation — System Noise (40 m)

4000 8000 12000

Frequency (MHz)

16000 20000

o

C3 ao

X

20

10OH

-10

-20

-30 H

-40

-50

-60

-70 H

-80

-90

-100 110

-120

Stamping Plant DRG to DRG — 60 m separation — System Noise (40 m)

4000 8000 12000

Frequency (MHz)

I 16000 20000

Figure F.3: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 50 m

separation. Bottom: 60 m separation.

92
stamping Plant: Directional transmit, receive antennas

20

10

-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

-110

-120

CQ73

O

-1

CU

X

Stamping Plant DRG to DRG — 75 m separation — System Noise (40 m)

4000 8000 12000

Frequency (MHz)

16000 20000

CQ-a

o

>-] .a

o

20 ^

10 --

-10 -

-20-

-30 ~

-40 -

-50 -

-60 H

-70

-80

-90 100

110

120

Stamping Plant DRG to DRG — 80 m separation — System Noise (80 m) n

4000 8000 12000

Frequency (MHz)

16000 20000

Figure F.4: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 75 m

separation. Bottom: 80 m separation.

93
stamping Plant: Directional transmit, receive antennas

20

10

-10

-20 ^ in

1/3 '8 -40

-J6 -50 « -60 H

5^ -70

-80

-90

-100

-110

-120

Stamping Plant DRG to DRG — 90 m separation

System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

20

10 H

-10

-20

-30 -

-40 -

-50

-60 -

-70 -

-80 -

-90

-100 H

-110

-120

Stamping Plant DRG to DRG — 100 m separation

System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure F.5: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top: 90 m

separation. Bottom: 100 m separation.

94
stamping Plant: Directional transmit, receive antennas

T3

O

-J

C3 CU

20^

10 -

- -10-

-20

-30

-40 -

-50 -

-60 - -70-

-80

-90 H

-100 -no

-120

Stamping Plant DRG to DRG — 1 10 m separation (A) — System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

20 -

100-

-10 -

-20-

m3 -30 -1

C/5 O

-J -40 -

COo

X

-50-

-60-

-70 -

-80-

-90 -

-100-

-110 -

-120 -

Stamping Plant DRG to DRG — 110 m separation (B)

- System Noise (80 m)

4000 8000 12000

Frequency (MHz)

16000 20000

Figure F.6: Excess path loss from 1 GHz to 12 GHz in the stamping plant. Top:

110 m separation, straight. Bottom: 110 m separation, around corner. See Figure 5-3.

95
Metal Stamping Plant: Directional transmit and receive antennas

20

10

-10-

-20-

-30

-40 -

-50

-60

-70

-80

-90

-100

-110

-120

Stamping Plant DRG to DRG

50 m separation 50 m separation - elevated, 6 o'clock 50 m separation - elevated, 3 o'clock 50 m separation - elevated, 1 2 o'clock 50 m separation - elevated, 9 o'clock

4000 8000 12000

Frequency (MHz)

16000 20000

Figure F.7: Excess path loss from 1 GHz to 12 GHz in the metal stamping plant

when the receive antenna is rotated through angles from zero (boresight) to 270° as

defined in Figure 5-3. Top: 50 m separation.

96
Appendix G: Engine Plant, Low-Frequency Data,

Omnidirectional Transmit and Receive Antennas

The following pages contain the complete set of measured data from the engine plant

covering a frequency range of 100 MHz to 1.5 GHz when omnidirectional transmit and

receive antennas were used.

97
Engine Plant: Omnidirectional transmit, receive antennas

40

20

COD

ro Q.

u

X

LU

mIa . hp

-20

-40

-60

-80 -

-100

.Aih.. i\

ii'ni m

iW%0'

J

^^/ M^ %M#

\ h

\. /

Engine Plant, biconicals 10m Separation

System Noise, 20m

250 500 750 1000

Frequency (MHz)

P^HiW

te#ft

f'-"' jiAi. ij

1250 1500

40

20

COo

Q.

I/) w

(Do

-20

-40

-60

-80 -

-100

^J1

JfcfM m^. lU ifiih

\ , X"!]' • '"Wiil '^f

IMF

'' k^j*''

m.

; I /y\ V ''itai*i#

Engine Plant, biconicals 20m Separation

System Noise, 20m

250

"1 I

I

^

I 500 750 1000

Frequency (MHz)

1250 1500

Figure G.1: Excess path loss from 100 MHz to 1.5 GHz in the engine plant. Top:

10 m separation. Bottom: 20 m separation.

98
Engine Plant: Omnidirectional transmit, receive antennas

sAM^fiil.^ifl||%|i

,

;

/ MM

''\J\

Engine Plant, biconicals 40m Separation

System Noise, 50m

System Noise, 20m

& fIfLifli

i I'^m

500 750 1000

Frequency (MHz)

1250 1500

40

20

T3

CL

LU

-20

-40

-60

-80 -

-100

'iiiiir'iiliiiiiS

Si,

mm

\Ml ill)fef.^l Mil

IP

I

' lisyii

VU^v^W' J V'' I

ill', .M.L;k{l m

Engine Plant, biconicals 50m Separation

System Noise, 50m

,/ Ifillil

I'l Ii\„.. J' !V

'''HUiigLll'' a*

"T ! r 250 500 750 1000

Frequency (MHz)

1250 1500

Figure G.2: Excess path loss from 100 MHz to 1.5 GHz in the engine plant. Top:

40 m separation. Bottom: 50 m separation.

99
Engine Plant: Omnidirectional transmit, receive antennas

40

20

o

as

0)o

X

LU

-40

-60

-80

-100

fill

Vm

'liffl

i

I

imi'^A

'ffmll|l in I' III' i III I

5^11 ''

Ir.MJiIiMiI

I ,111 1

I

I

i

1

Engine Plant, biconlcals 60m Separation

System Noise, 50m

"T : I [""

"

250 500 750 1000

Frequency (MHz)

'•'' rA'

m %

'ii'i

'1?'

,i.,i .1^ WfM

1250 1500

40

20

m

a

Q.

COw

(Uo

X

LU

-20

-40

-60

-80

-100

Engine Plant, biconicals 80m Separation

System Noise, 120m B

I System Nojfee, 50m i u ki t i hy}h ''ii mkf%kLM

500 750 1000

Frequency (MHz)

1500

Figure G.3: Excess path loss from 100 MHz to 1.5 GHz in the engine plant. Top:

60 m separation. Bottom: 80 m separation.

100
Engine Plant: Omnidirectional transmit, receive antennas

AO'fU Engine Plant, biconicals 100m Separation

20-

-i

CO

i

il' L System Noise, 12Qm B W ll

.'ill

1

m,hhi I'

' ! r

1

i III'

1 4

i I'l'

''If

\!\ik

ill I'll

''i

'

ii'l f f

iiii'fe

ill

1'' If

S -20 -| '! Ml 'If fi

1 _i n

'

'

1

i '' 1

1 £

'

' 1 TO ! Q.

CO -40

CO ,1 CD I O _|l X ' LU

1 -60 ^ j!,

: II -1

-80- 10i'lf

ill

'ill

ji, :|l|lilli! i; ififi i|

i r\n

'

i 1 1 "1 vr r: 1 1 M' '

1 |i r ,

' i|''ii'' '' nil 1 - 1 uu — 1 ' 1 ' 1

' ' 250 500 750 1000 1250 1500

Frequency (MHz)

AC\ ^u

Engine Plant, biconicals

1 20m-A Separation

20 -

0-1

CD

CO 1

1 c- ystem Noise, 120m B

i ^ L_ o,1 J

iu'lii! if1' 'il' 1 1fi'}" iff i

1

ill ^,#if

S -20 i Ml'rj f ' ' i'

' |l : :|[ ii

i.i

1 _i 1

'

1

' ^

]

'

i TO

' 1 Q.

CO -40 -i i CO il CD 1

1 o '1

i X 1 LU -60 - 1}

III

'

1

Il • d'i,.li.i - 1'

-80 -

' ' f i ii i(T|"l

1

1 f r u 11

' ii'i'i II I III mm.

Il !

^ 'IfliW i1 'i(

•M

^ nci

i| ''111' ifll'i"' >\ '"'I'l ' IP' '1 !' I'ji'i l''ii'iiir i! if' ( '

1 - lUU — 1

I

1

' 1 1 1 1 1

1

\ -- r 250 500 750 1000 1250 1500

Frequency (MHz)

Figure G.4: Excess path loss from 100 MHz to 1.5 GHz in the engine plant. Top:

100 m separation. Bottom: 120 m separation, straight path (see Figure 5-6).

101
Engine Plant: Omnidirectional transmit, receive antennas

40

20

en

Q.

OX

LU

-40

-60

-80

-100 imu

I imAf--**'-''*

Engine Plant, biconicals 120m-B Separation

Systerji Noise, 120m B

li'ifil i'liliii'!!Mi4 iw

'111

ik

250 500 750 1000

Frequency (MHz)

MMs

1250 1500

Figure G.5: Excess path loss from 100 MHz to 1.5 GHz in the engine plant. Top:

120 m separation, corner path (see Figure 5-6).

102
Appendix H: Engine Plant, High-Frequency Data, Directional

Transmit Antenna, Omnidirectional Receive Antenna

The following pages contain the complete set of measured data from the engine plant

covering a frequency range of 500 MHz to 18 GHz when a directional transmit antenna

and an omnidirectional receive antenna were used.

103
Engine Plant: Directional transmit, omnidirectional receive antennas

40

20

Engine Plant, DRG-tophat

10m Separation

System Noise, 10m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

40

Engine Plant, DRG-tophat

20m Separation

System Noise, 10m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure H.1: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top: 10 m

separation. Bottom: 20 m separation.

104
Engine Plant: Directional transmit, omnidirectional receive antennas

CQ

•a

a.

tn

(/) o

X

LU

-100

40

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Engine Plant, DRG-tophat

50m Separation — System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure H.2: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top: 40 m

separation. Bottom: 50 m separation.

105
Engine Plant: Directional transmit, omnidirectional receive antennas

40

20

Engine Plant, DRG-tophat

60m Separation

System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

40

20

Engine Plant, DRG-tophat

80m Separation

System Noise, 120m-B

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure H.3: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top: 60 m

separation. Bottom: 80 m separation.

106
Engine Plant: Directional transmit, omnidirectional receive antennas

40

-

Engine Plant, DRG-tophat

100m Separation

System Noise, 120m-B

-60

-80

-100

40

20

I II

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Engine Plant, DRG-tophat

120m-A Separation

System Noise, 120m-B

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure H.4: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top:

100 m separation. Bottom: 120 m separation, straight path (see Figure 5-6).

107
Engine Plant: Directional transmit, omnidirectional receive antennas

40

20

Engine Plant, DRG-tophat

120m-B Separation

System Noise, 120m-B

QQT3

(0 Q.

C/3 O

X

LU

-100 2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure H.5: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top:

120 m separation, corner path (see Figure 5-6).

108
Appendix I: Engine Plant, Higli-Frequency Data, Directional

Transmit and Receive Antennas

The following pages contain the complete set of measured data from the engine plant

covering a frequency range of 500 MHz to 18 GHz when directional transmit and

receive antennas were used.

109
Engine Plant: Directional transmit, receive antennas

40

20

CD

-a

Engine Plant, DRG-DRG

10m Separation

System Noise, 50m

Mif^fff'f^^YsfVvy^^ —nV

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

40

COo

CD CL

(/>

(/> CDO

X

LU

Engine Plant, DRG-DRG

20m Separation

System Noise, 50m

fifMftih

-100 2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure 1.1: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top: 10 m

separation. Bottom: 20 m separation.

110
Engine Plant: Directional transmit, receive antennas

40

20 -

Engine Plant, DRG-DRG

40m Separation

System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

40

20

Engine Plant, DRG-DRG

50m Separation

System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure 1.2: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top: 40 m

separation. Bottom: 50 m separation.

111
Engine Plant: Directional transmit, receive antennas

40

20

Engine Plant, DRG-DRG

60m Separation

System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

40

20

COo

CO a.

CO

CO

(Uo

X

LU

-40

-60

-80

Engine Plant, DRG-DRG

80m Separation

System Noise, 50m

-100 2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure 1.3: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top: 60 m

separation. Bottom: 80 m separation.

112
Engine Plant: Directional transmit, receive antennas

40

20

CO

T3

CO a.

CO

(/> 0)o

X

UJ

Engine Plant, DRG-DRG

100m Separation

System Noise, 50m

-100

40

20 -

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Engine Plant, DRG-DRG

120m-A Separation

System Noise, 50m

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (MHz)

Figure 1.4: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top:

100 m separation. Bottom: 120 m separation, straight path (see Figure 5-6).

113
Engine Plant: Directional transmit, receive antennas

40

20 -

-

T3

CD a.

(/] o

X

LU

Engine Plant, DRG-DRG

120m-B Separation

System Noise, 50m

-40

-60

-80

-100

2000 4000 6000 8000 10000 12000 14000 16000 18000

Frequency (IVIHz)

Figure 1.5: Excess path loss from 500 MHz to 18 GHz in the engine plant. Top: 120 m

separation, corner path (see Figure 5-6).

114
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Administrative Services Act of 1949 as amended. Public Law 89-306 (79 Stat. 1 127), and as implemented by

Executive Order 1 1717 (38 FR 12315, dated May 1 1,1973) and Part 6 of Title 15 CFR (Code of Federal

Regulations).

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VA 22161, in hard copy, electronic media, or microfiche form. NISTIR's may also report results of NIST projects of

transitory or limited interest, including those that will be published subsequently in more comprehensive form.
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