MORE ON THE $30 MILLION DOLLAR RADIO UPGRADE (radios are more important than service of course)

Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 1
ENGINEERING SHOWING TO SUPPORT APPLICATION FOR NINETEEN
NEW 700 MHz NARROWBAND 25 kHz CHANNEL BLOCKS BY TRIMET,
PORTLAND, OREGON

Introduction
This Engineering Showing supports a new application for nineteen (19) 700 MHz narrowband 25
kHz channel blocks by the Tri-County Metropolitan Transportation District of Oregon, dba TriMet,
in Portland, Oregon (“TriMet”). The Tri-County Metropolitan Transportation District of Oregon is a
municipal corporation of the State of Oregon, as defined in.ORS267. As such TriMet has the same
status, responsibilities, and authority as a municipality under Oregon law and complies with the
eligibility requirements for 700 MHz licensing as defined in §90.523(a) of the Commission’s Rules.
TriMet operates the regional transit system in Washington, Multnomah, and Clackamas Counties in
northwestern Oregon. All of the fixed route coaches, paratransit vehicles and light rail vehicles
operated by TriMet now use the existing TriMet voice radio system and the City of Portland 800
MHz trunked radio system. TriMet’s fixed route and paratransit vehicles also now use the existing
TriMet UHF transit data radio system.
Security services for the TriMet system are provided by sworn law enforcement officers from the
three counties in the TriMet service area. These officers will be able to use the new TriMet voice
radio system to communicate with TriMet Operations Command Center personnel over radio in
emergency situations, though the normal mode for day-to-day security operations is communication
from command center-to-command center.
The radio system is also used on a daily basis to provide communication critical to the protection of
the safety of life, health, and property of the public and TriMet personnel.
Providing reliable voice and data radio communications for TriMet’s regional transit system is an
essential part of providing transportation services to the public in the Portland Metro region as part of
local government’s mandate to provide services to the public and to provide for public safety.
TriMet is also the primary emergency evacuation agency for disasters and large-scale incidents in the
Portland Metro region and is actively involved in emergency and homeland security planning for the
region. The TriMet radio system is the primary avenue for interoperable communications between
TriMet and local law enforcement and fire agencies.
The nineteen (19) 700 MHz narrowband channel blocks requested herein will be used as transit
mobile data channels as part of a new Computer-Aided Dispatch (CAD)/Automatic Vehicle Location
(AVL) and Trunked Voice Radio System now being implemented by TriMet (“TriMet”). The voice
and data communication needs of the TriMet fixed route and paratransit fleets are now served by its
existing 3-site, 12-channel UHF conventional radio system. The voice communications needs of
TriMet’s light rail system and field supervisors are now served by the City of Portland 800 MHz
Public Safety Radio System. The existing UHF system is well beyond its expected end of life, and
there are “intraoperability” issues within TriMet’s own communications system as a result of
operation on two separate systems in two different frequency bands. The proposed 700 MHz voice
and data radio system will allow TriMet to operate on a single, integrated modern radio system
designed to meet its voice and data communications needs well into the future.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 2
The data communications provided by this system will support Computer-Aided Dispatch and
Automatic Vehicle Location functions that are essential for managing TriMet’s revenue service,
responding to emergencies, and ensuring the safety and security of over 102.6 million riders per year
on TriMet’s fixed route, paratransit, light rail, and commuter rail systems.
The voice portion of the new radio system will operate as a standard centralized control trunked radio
system. The transit mobile data portion of the system will also be effectively trunked, since data
channels will be assigned automatically to vehicles based on their location and on a predetermined
assignment scheme that will allocate channels across the entire TriMet fixed route, paratransit, and
non-revenue vehicle fleet.
Each of the 19 new 700 MHz 25 kHz narrowband channel blocks will be split into discrete 12.5 kHz
channels, which will be used to provide voice communications with fixed route, paratransit, light rail,
and non-revenue vehicles and personnel; data communications with fixed route and non-revenue
vehicles; and to enable advanced CAD/AVL functionality for the TriMet fixed route and paratransit
fleets..
Proposed 700 MHz Narrowband Channels
This application proposes the use of 30 12.5 kHz channels taken from 19 of the 37 (thirty-seven) 700
MHz 25 kHz narrowband General Use channel blocks allocated to Washington County, Multnomah
County and Clackamas County in the most recent draft of the Regional Plan for the Public Safety
700 MHz Band in Region35 (Oregon) (“Region 35 700 MHz Plan”).
The system design for the proposed new TriMet 700 MHz system uses four repeater sites:
• Council Crest
• Pete’s Mountain
• Mt. Scott
• Polivka Hill
The thirty 12.5 kHz 700 MHz channels will distributed among the 4 proposed TriMet sites, all of
which are located in the Portland metro area, it was necessary to evaluate all of the available channels
assigned to Washington, Multnomah, and Clackamas Counties, as shown in Appendix G (Channel
Block Assignments by County) of the Region 43 700 MHz Plan, to determine which channels could
be used with the least risk of interference to future adjacent channel systems in the Counties in
northwestern Oregon and southwestern Washington adjacent to the three counties in the Portland
metro area. The channel blocks which were determined to be most appropriate for use by TriMet are
listed below, which shows the 25 kHz blocks proposed for use by TriMet and the distribution of the
proposed 12.5 kHz frequency pairs among the four repeater sites is shown below in Table 1.
For the control channels and for the polling data channels, a single 12.5 kHz segment of a 25 kHz
block was assigned to each site. For the voice channels and the packet data channels used in the
system, both 12.5 kHz segments of each 25 kHz block were used, with the two 12.5 kHz segments in
each 25 kHz block assigned to different repeater sites. Analysis of the potential for intra-system
interference resulting from adjacent 12.5 kHz channels keying up at adjacent sites shows that the
adjacent channel rejection provided by the mobile and portable radios is sufficient to prevent
degradation of the performance of the voice channels. Because the polling data and control channels
are so critical to the proper operation of the system, and because the impact of bit errors for these
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 3
channels is more significant than for the voice and packet data channels, adjacent 12.5 kHz channels
from the same 25 kHz block are not used for these channels in order to provide the most conservative
possible implementation of the control channel and polling channels.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 4
TriMet
Channel
Number
12.5 kHz
Channel
County
Base
Channel #
Base
Frequency
Mobile
Frequency Council Crest Mt. Scott Petes Polivka
Channel 1 A 769.33125 799.33125 Control Channel 1
B 769.34375 799.34375
Channel 2 A 769.85625 799.85625 Control Channel 2
B 769.86875 799.86875
Channel 3 A 770.28125 800.28125 Control Channel 3
B 770.29375 800.29375
Channel 4 A 774.18125 804.18125 Control Channel 4
B 774.19375 804.19375
Channel 5 A 770.08125 800.08125 Voice Channel 1
B 770.09375 800.09375 Voice Channel 15
Channel 6 A 771.25625 801.25625 Voice Channel 2
B 771.26875 801.26875 Voice Channel 10
Channel 7 A 771.68125 801.68125 Voice Channel 3
B 771.69375 801.69375 Voice Channel 11
Channel 8 A 772.05625 802.05625 Voice Channel 4
B 772.06875 802.06875 Voice Channel 12
Channel 9 A 770.33125 800.33125 Voice Channel 5
B 770.34375 800.34375 Voice Channel 13
Channel 10 A 771.75625 801.75625 Voice Channel 6
B 771.76875 801.76875 Voice Channel 14
Channel 11 A 771.20625 801.20625 Voice Channel 7
B 771.21875 801.21875 Voice Channel 16
Channel 12 A 771.48125 801.48125 Voice Channel 8
B 771.49375 801.49375 Voice Channel 17
Channel 13 A 772.85625 802.85625 Voice Channel 9
B 772.86875 802.86875 Packet Data 5
Channel 14 A 772.43125 802.43125 Packet Data 1
B 772.44375 802.44375 Packet Data 3
Channel 15 A 773.23125 803.23125 Packet Data 2
B 773.24375 803.24375 Packet Data 4
Channel 16 A 774.90625 804.90625 Polling 3
B 774.91875 804.91875
Channel 17 A 771.03125 801.03125 Polling 1
B 771.04375 801.04375
Channel 18 A 772.35625 802.35625 Polling 2
B 772.36875 802.36875
Channel 19 A 773.98125 803.98125 Polling 4a Polling 4b Polling 4c
B 773.99375 803.99375
Multnomah 797-802
Washington 829-832
Washington 677-680
Multnomah 537-540
Washington 945-948
Clakamas 617-620
Washington 549-552
Clakamas 353-356
Clakamas 397-400
Clakamas
Clakamas
Multnomah
Washington
Washington
Washington
Washington
Washington
Multnomah
Multnomah
325-328
205-208
137-140
53-56
173-176
361-364
429-432
489-492
213-216
441-444
Table 1 - Proposed TriMet 12.5 kHz 700 MHz Frequencies by Site
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 5
The frequency spacing relationships between the proposed TriMet 25 kHz blocks and the nearest 700
MHz assignments in other nearby Counties in northwestern Oregon and southwestern Washington
are shown below:
Channel 53-56
County Closest Frequency Spacing (kHz)
Yamhill County 50
Multnomah County 250
Clark County 50
Cowlitz County 50
Skamania County 50
Channel 137-140
County Closest Frequency Spacing (kHz)
Hood River County 75
Yamhill County 75
Clark County 75
Cowlitz County 75
Skamania County 75
Channel 173-176
County Closest Frequency Spacing (kHz)
Hood River County 25
Yamhill County 50
Clark County 50
Cowlitz County 50
Skamania County 50
Channel 205-208
County Closest Frequency Spacing (kHz)
Hood River County 75
Multnomah County 50
Channel 213-216
County Closest Frequency Spacing (kHz)
Hood River County 25
Clackamas County 50
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 6
Channel 325-328
County Closest Frequency Spacing (kHz)
Hood River County 25
Multnomah County 175
Washington County 200
Channel 353-356
County Closest Frequency Spacing (kHz)
Columbia County 150
Hood River County 75
Multnomah County 75
Washington County 50
Skamania County 50
Channel 361-364
County Closest Frequency Spacing (kHz)
Columbia County 100
Hood River County 25
Yamhill County 175
Clackamas County 50
Multnomah County 125
Skamania County 100
Channel 397-400
County Closest Frequency Spacing (kHz)
Hood River County 25
Marion County 75
Yamhill County 50
Multnomah County 100
Washington County 200
Clark County 50
Cowlitz County 50
Channel 429-432
County Closest Frequency Spacing (kHz)
Hood River County 25
Marion County 50
Yamhill County 225
Clackamas County 200
Multnomah County 75
Clark County 100
Cowlitz County 100
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 7
Channel 441-444
County Closest Frequency Spacing (kHz)
Columbia County 175
Hood River County 50
Marion County 125
Yamhill County 150
Clackamas County 225
Washington County 75
Clark County 100
Cowlitz County 50
Channel 489-492
County Closest Frequency Spacing (kHz)
Columbia County 75
Hood River County 100
Marion County 50
Yamhill County 150
Clackamas County 75
Clark County 50
Cowlitz County 25
Channel 537-540
County Closest Frequency Spacing (kHz)
Columbia County 50
Hood River County 25
Marion County 125
Yamhill County 100
Washington County 75
Cowlitz County 75
Channel 549-552
County Closest Frequency Spacing (kHz)
Columbia County 50
Hood River County 50
Marion County 100
Yamhill County 25
Clackamas County 275
Multnomah County 75
Clark County 75
Cowlitz County 150
Skamania County 100
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 8
Channel 617-620
County Closest Frequency Spacing (kHz)
Columbia County 50
Marion County 75
Multnomah County 175
Washington County 75
Clark County 100
Skamania County 25
Channel 677-680
County Closest Frequency Spacing (kHz)
Marion County 225
Yamhill County 75
Multnomah County 100
Cowlitz County 25
Channel 797-802
County Closest Frequency Spacing (kHz)
Columbia County 100
Marion County 75
Cowlitz County 25
Channel 829-832
County Closest Frequency Spacing (kHz)
Marion County 50
Yamhill County 25
Clark 25
Channel 945-948
County Closest Frequency Spacing (kHz)
Marion County 25
The use of these specific frequencies, along with proper system design which will limit the
“footprint” of the proposed TriMet 700 MHz subsystem outside the intended service area, should
preclude the potential for interference to other currently proposed and future 700 MHz systems in
northwestern Oregon and southwestern Washington.
Coverage and Interference Maps
The application filing procedure described in the Region 35 700 MHz Plan states that “applicants
must [also] submit an interference prediction map using TIA/EIA TSB 88-A guidelines. The map
must show all interference predicted.” It is not entirely clear from the language of the Region 35 700
MHz Plan what sort of interference analysis is required.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 9
There is an extensive and detailed set of co-channel and adjacent channel interference analysis
techniques described in TSB-88, but they are meant to be used in the analysis of potential
interference from a new facility to existing incumbent licensed facilities with well-defined repeater
sites, antenna patterns, and effective radiated power levels. These techniques are not well suited to
interference analysis in circumstances where there are no existing incumbent facilities, as is the case
with this application, because they require well-defined repeater sites for the other potentially
affected licensees. Since there are no existing 700 MHz systems in Oregon, there are no existing
repeater sites and systems to be used as input data for the TSB-88 analysis.
In addition, the only implementation of these TSB-88 techniques in commercially available software
that we know of is the implementation in ComStudy, which has been used in the past by public safety
frequency coordinators to analyze new applications (primarily in the VHF and UHF bands) and their
impact on incumbent licensees. The use of the ComStudy TSB-88 interference analysis routines in
the VHF and UHF bands has been suspended by the public safety frequency coordinators because
these routines do not produce consistent results.
The interference maps shown below in this Engineering Study are based on the requirements for
coverage and interference maps for new 700 MHz system described in the Region 43 (Washington)
700 MHz Application Review Procedure, which are based in turn on the NCC 700 MHz Pre-
Assignment Rules/Recommendations. The D/U (Desired-to-Undesired) signal ratios for co-channel
and adjacent-channel interference analysis shown in that document are based on analysis techniques
and assumptions taken from TSB-88 and on the adjacent channel power (“ACP”) limitations
embodied in §90.543 of the FCC’s Rules.
As described in detail in the NCC 700 MHz Pre-Assignment Rules/Recommendations document, the
D/U ratios for co-channel and adjacent/alternate channel interference analysis:
Co-channel: 35 dB D/U ratio
Adjacent/Alternate Channel: -20 dB D/U ratio
These D/U ratios are translated into prohibited Interference/Protected contour overlap values, as
follows:
• Co-Channel: the Interfering 5 dBμ F(50,50) contour may intercept but not overlap the
Protected 40 dBμ F(50,50) contour.
• Adjacent/Alternate Channel: the Interfering 60 dBμ F(50,50) contour may intercept but not
overlap the Protected 40 dBμ F(50,50) contour.
The adjacent alternate channel analysis in the NCC document uses an ACCPR (“Adjacent Channel
Coupled Power Ratio”) value of 65 dB for adjacent 25 kHz channel blocks. The NCC analysis rounds
the contour value produced by this ACCPR figure down from 61.6 dBμ to 60 dBμ (this expands the
size of the contour) to be conservative, due to the possibility of multiple interference sources; this
allows the Interfering contour to be approximately 20 dB above the 40 dBμ Protected contour, at 60
dBμ.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 10
The coverage and interference maps shown below depict both the predicted contours appropriate for
each circumstance (Service Area coverage, Adjacent/Alternate Channel Interference, and Co-Channel
Interference) and tile-based predictions of the extent of predicted field strength levels greater than or
equal to the contour value. Both the contours and the tile-based field strength predictions are based
on the TriMet facilities proposed in this application, as shown in the attached FCC Form 601.
The 40 dBμV/m coverage maps (Figure 1 below), the 5 dBμV/m co-channel interference maps
(Figure 2 below), and the 60 dBμV/m adjacent channel interference map (Figure 3 below)
demonstrate compliance with the requirements of the Region 35 700 MHz Regional Plan with respect
to the potential for interference with present and future 700 MHz systems in northwest Oregon and
with the requirements of the Region 43 700 MHz Plan with respect to the potential for interference
with present and future 700 MHz systems in southwest Washington.
These maps show both the pertinent F(50,50) contours described above and grid-based field strength
predictions which show all areas in which the predicted field strength equals or exceeds the pertinent
value for each map in the counties in southwest Washington and northwest Oregon adjacent to the
TriMet three-county service area.
The contour predictions were produced using the algorithm in the ComStudy program (version
2.2.14.19), which is the same program used by the APCO frequency coordinators to produce contour
prediction studies. The service and interference contours shown in the map are based on 50% time
and 50% location statistics, 360 radials, and the digitized terrain database included in the ComStudy,
which is a hybrid database containing 3 arc-second, 30 meter, and 10 meter terrain data.
All of the grid-based predictions shown in the maps were generated using Version 1.2.2 of the
Longley-Rice propagation model and the USGS NED 1 arc-second digitized terrain database. The
40 dBμV/m coverage predictions, as well as 5 and 25 dBμV/m interference predictions, are based on
50% location and 50% time statistics. Both the coverage and interference maps include USGS Land
Use Land Clutter (“LULC”) data for each prediction grid. The LULC data is used to provide an
appropriate “clutter loss” value for each grid location based on the characteristics of the urbanization
and land cover at that location.
The Confidence Factor used for the predictions is 50%; this is a more conservative assumption than a
higher confidence factor (such as the 95% Confidence Factor described in Section 2 of the Region 43
Application Filing Procedure document, for example) because the 50% Confidence Factor value
produces higher predicted service and interference field strength levels than the 95% Confidence
Factor value.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 11
Figure 1 - Proposed 40 dBμV/m F(50,50) Service Contours and Coverage
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 12
The proposed 4-site system has been designed to replicate (and improve wherever possible) the
coverage of TriMet’s existing UHF fixed route and paratransit radio system and its existing light rail
and supervisor voice radio coverage now provided over the City of Portland 800 MHz trunked radio
system. The goal of the system design is to produce the same coverage for both the voice and the
mobile data segments of the new transit radio system being implemented by TriMet.
Because the system uses relatively high sites, all of which are located within TriMet’s three-county
service area , some extension of both the 40 dBμ contours and the 40 dBμ predicted coverage outside
the service area is unavoidable, as shown in Figure 1 above. In particular, the extensions into
Yamhill, Polk, and Marion Counties to the south and west of the Pete’s Mountain site occur as a
result of the need to provide coverage over a wide range of azimuths, including those to the south and
west, to provide service to Clackamas County and Washington County. The extensions to the north
and east into Columbia County, Oregon and Clark, Cowlitz, and Skamania Counties in Washington
are a result of the need to provide coverage to the portions of TriMet’s service area in Washington
and Multnomah Counties.
Figure 2 below shows the proposed 5 dBμ F(50,50) adjacent channel interference contour and the
areas covered with a field strength of 5 dBμ F(50,50) or greater by the proposed new TriMet radio
system.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 13
Figure 2 - Proposed 5 dBμV/m F(50,50) Co-Channel Interference Contours and Field Strength
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 14
Region 35 Co-Channel Analysis
The nearest co-channel assignments in the Region 35 700 MHz table of Channel Block Assignments
by County (Appendix G of the Region 35 700 MHz Plan) are in Lane County (Channels 549-552,
829-832 and 945-948). There are also co-channel assignments in Douglas, Coos, Curry, Josephine,
and Jackson Counties. All of these co-channel assignments are sufficiently distant from the proposed
TriMet sites in Multnomah and Clackamas Counties that there is very little likelihood of co-channel
interference resulting from the proposed use of nineteen 700 MHz channel blocks proposed by
TriMet.
As shown in Figure 2 above, the proposed 5 dBμV/m contour extends only as far south as the middle
of Linn County. There is a small area in the northernmost portion of Lane County west of Interstate
5 where the predicted field strength from the TriMet system exceeds 5 dBμV/m. The predicted 5
dBμV/m field strength does not extend into the other Oregon Counties with co-channel assignments
south of Lane County.
Figure 3 below shows the carrier-to-interference ratio for the desired signals from an assumed 700
MHz public safety system in Lane County at the Prairie Peak, Bear Mountain, and Mt. Hagan sites,
which are the sites now used by Lane County for its trunked UHF radio system, and the undesired
signals from the proposed TriMet system. Only the Council Crest, Mt. Scott, and Polivka Hill sites
are included in the C/I calculations because those are the sites at which 25 kHz channel blocks cochannel
with Lane County are used.
The assumed Lane County 700 MHz transmit channel parameters are similar to those used in the
proposed TriMet system; the antenna elevation assumed for the hypothetical 700 MHz system is the
antenna elevation now used for the existing UHF system at each site. Areas shown in blue are those
where the Desired-to-Undesired signal ratio is 35 dB or greater; areas shown in red are those where
the Desired- to-Undesired signal radio is less than 35 dB. Areas with no color shading are those areas
where the predicted desired signal is below the minimum threshold for the study, which is -120
dBmW at the receiver (equivalent to 12.9 dBμV/m field strength for a 0 dBd gain receiving antenna
system).
As shown Figure 3, there are some small areas with elevated terrain in the northern portion of Lane
County west of Highway 99 where the predicted Desired-to-Undesired signal ratio is less than 35 dB.
However, these are areas which are shadowed from the three assumed sites such that the desired 700
MHz signal levels from the hypothetical Lane County system are significantly lower than they would
be for a full 700 MHz countywide system design, which would undoubtedly use more than 3 sites to
provide county-wide 700 MHz coverage. The predicted undesired signals at these locations are
primarily from the Council Crest site and occur at levels below -120 dBmW for a receive antenna
system net gain of -1.0 dB.
Figure 4 below shows the carrier-to-interference ratio for the desired signals from the proposed
TriMet system and the undesired signals from the hypothetical Lane County 700 MHz public safety
system described above. Areas shown in blue are those where the Desired-to-Undesired signal ratio is
35 dB or greater; areas shown in red are those where the Desired- to-Undesired signal radio is less
than 35 dB. Areas with no color shading are those areas where the predicted desired signal is below
the minimum threshold for the study, which is -120 dBm at the receiver (equivalent to 13.9 dBμV/m
field strength for a -1.0 dBd gain receiving antenna system).
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 15
The circumstances depicted in Figure 4 are similar to those shown in Figure 3. There are some
limited areas where the predicted D/U ratio for TriMet as the desired signal in relation to the
undesired signal from the hypothetical Lane County System is less than 35 dB, but these areas are
primarily outside of the TriMet service area or are in areas where TriMet does not have routes. As in
the previous case, the predicted signal levels from the Lane County system are below -120 dBm at
the victim receivers at these locations; in addition, TriMet does not have existing routes in most of
these areas.
Region 43 Analysis
The predicted 5 dBμV/m field strength plot shown in Figure 2 above extends into Clark, Cowlitz,
Skamania, and Wahkiakum Counties in Washington. There are no co-channel assignments listed in
the Region 43 700 MHz table of Channel Block Assignments by County (Appendix G of the Region
43 700 MHz Plan) in any of these counties. The nearest co-channel assignments in western
Washington are in Thurston County (205-208 and 325-328). As shown in Figure 2, the predicted 5
dBμV/m field strength from the proposed TriMet system does not extend as far north as Thurston
County.
Based on the analysis shown above, the channels proposed for use in the proposed TriMet as
configured as shown in this Engineering Showing and the attached FCC Form 601 have little
potential to cause significant co-channel interference to future well-engineered 700 MHz systems in
Oregon State or Washington State.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 16
Figure 3 – Carrier-to-Interference Map – Hypothetical Lane County System (Desired) vs. Proposed TriMet System (Undesired)
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 17
Figure 4 – Carrier-to-Interference Map – Proposed TriMet System (Desired) vs. Hypothetical Lane County System (Undesired)
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 18
The nearest adjacent channel assignment shown in Appendix G of the Region 35 700 MHz plan is the
25 kHz block 941-944, which is assigned to Marion County and is the adjacent channel block below
the proposed 25 kHz channel block 945-948. The 945-948 channel block is used at the Mt. Scott site
in the proposed TriMet system. The nearest adjacent channel assignment shown in Appendix G of
the Region 43 700 MHz plan is the 25 kHz block 833-836, which is assigned to Clark County and is
the adjacent channel block below the proposed 25 kHz channel block 829-832. The 829-823 channel
block is used at the Polivka Hill site in the TriMet system.
As shown in Figure 5 below, neither the proposed 60 dBμV/m interference contours nor the predicted
60 dBμV/m field strength from the Mt. Scott site extend into Marion County. Both the 60 dBμV/m
contours and the 60 dBμV/m field strength are limited to relatively small areas surrounding the
proposed Mt. Scott repeater sites.
As shown in Figure 6 below, neither the proposed 60 dBμV/m interference contours nor the predicted
60 dBμV/m field strength from the Polivka Hill site extend into Clark County. Both the 60 dBμV/m
contours and the 60 dBμV/m field strength are limited to relatively small areas surrounding the
proposed Polivka Hill repeater site.
Figure 7 below shows the proposed 60 dBμ F(50,50) adjacent channel interference contours from all
four repeater sites and the areas covered with a field strength of 60 dBμ or greater by the proposed
new TriMet radio system.
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 19
Figure 5 - Mt. Scott 60 dBμV/m F(50,50) Adjacent-Channel Interference Contours and Field Strength
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 20
Figure 6 - Polivka 60 dBμV/m F(50,50) Adjacent-Channel Interference Contours and Field Strength
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 21
Figure 7- Proposed 60 dBμV/m F(50,50) Adjacent-Channel Interference Contours and Field Strength (All Sites)
Engineering Showing April 29, 2010
TriMet Application for New 700 MHz Channels
HATFIELD & DAWSON CONSULTING ENGINEERS 22
[The proposed operation at the four new sites shown in this application has been approved
by the Region 35 700 MHz Regional Planning Committee, as shown in the memo attached
to this Engineering Showing. TO BE ADDED AFTER APPROVAL]