UNITED STATES DEPARTMENT OF AGRICULTURE

**Rural Electrification Administration**

**BULLETIN 1751H-703**

**SUBJECT: [BETRS Radio Systems]{.underline}**

**TO:** Telephone Borrowers

REA Telephone Staff

**EFFECTIVE DATE:** Date of Approval

**EXPIRATION DATE:** Three years from effective date

**OFFICE OF PRIMARY INTEREST:** Transmission Branch,

Telecommunications Staff Division

**PREVIOUS INSTRUCTIONS:** This bulletin replaces the following
Telecommunications Engineering and Construction Manual Sections:

TE&CM 948, Basic Exchange Telecommunications Radio Service

TE&CM 949, BETRS Radio Application Guidelines

**FILING INSTRUCTIONS:** Discard the following Telecommunications
Engineering and Construction Manual Sections:

TE&CM 948, Basic Exchange Telecommunications Radio Service

TE&CM 949, BETRS Radio Application Guidelines

Replace with this bulletin.

**PURPOSE:** To provide information on Basic Exchange Telecommunications
Radio Service, or BETRS. This bulletin includes a tutorial that provides
a basic description of the BETRS concept and equipment. It also provides
BETRS application guidelines and recommendations. All information in
this bulletin is advisory.

Gary C. Byrne 09/18/91

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Administrator Date

**TABLE OF CONTENTS**

**1. OVERVIEW**
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5

1.1 General
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5

1.2 Subscriber Radio Equipment
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**2. BETRS EQUIPMENT AND SYSTEMS**
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2.1 Introduction
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7

2.2 BETRS Equipment Description
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2.2.1 Point-to-Multipoint Systems
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2.2.2 Base Radio Station
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2.2.3 Modular Base Station
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2.2.4 Subscriber Radio Station
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2.2.5 Repeater Radio Station
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2.2.6 Point-to-Point Systems
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2.2.7 Rural Radio Equipment
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2.2.8 Radio Propagation Patterns
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2.3 Present Analog Equipment
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2.4 Evolving Digital Equipment
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2.5 Transition Toward Future
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**3. BETRS APPLICATION**
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16

3.1 General
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16

3.2 Equipment and System Characteristics
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3.3 Preliminary Planning
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3.4 Radio System Design
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3.5 FCC Radio Station Authorization
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3.6 System Specifications
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3.7 System Proposals
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26

3.8 System Implementation
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APPENDIX 1 BETRS HISTORY
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APPENDIX 2 EXAMPLE OF BETRS EQUIPMENT SPECIFICATIONS
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FIGURE 1 POINT-TO-MULTIPOINT BETRS RADIO SERVICE
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FIGURE 2 POINT-TO-POINT MICROWAVE RADIO SUBSCRIBER SERVICE
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FIGURE 3 POINT-TO-POINT BETRS RADIO SERVICE
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FIGURE 4 POINT-TO-POINT RURAL RADIO SERVICE
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FIGURE 5 POINT-TO-MULTIPOINT BETRS RADIO SERVICE AREA
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FIGURE 6 BASE RADIO STATION
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FIGURE 7 MODULAR BASE STATION
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FIGURE 8 SUBSCRIBER RADIO STATION
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FIGURE 9 BETRS RADIO REPEATER SERVICE AREA
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FIGURE 10 RADIO FREQUENCIES - BASIC SYSTEM
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FIGURE 11 RADIO FREQUENCIES - SYSTEM WITH REPEATER
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FIGURE 12 RADIO PROPAGATION PATTERNS
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FIGURE 13 TIME DIVISION MULTIPLE ACCESS
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FIGURE 14 SIMPLIFIED PROFILE VIEW OF RADIO PATH
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INDEX:

Basic Exchange Telecommunications Radio Service

BETRS

BETRS Radio Systems

BETRS Radio Application

**ABBREVIATIONS & DEFINITIONS**

The principal abbreviations and terms are defined in a generic manner as
they are commonly used in this bulletin and in telecommunications. These
abbreviations and definitions are intended to provide descriptive
illustrations to better understand BETRS concepts, equipment, and
applications. The list contains a limited number of abbreviations and
terms, and the definitions are not intended to be complete and precise.
Additional digital transmission terms are covered in Bulletin 1751H-403.

**AC:** Alternating Current.

**ADPCM:** Adaptive Differential Pulse Code Modulation, a digital coding

technique.

**Base Radio Station:** All equipment located at the BETRS central
office radio

terminal site. (FCC term: Central Office Station.)

**BETRS:** Basic Exchange Telecommunications Radio Service, a radio
service

authorized by the FCC in the 150, 450 and 800 MHz bands.

**Cellular:** Refers to Cellular Radio Service (or equipment), a mobile
radio

service authorized by the FCC in the 800 MHz band.

**Codec:** Coder and Decoder; used for analog to digital encoding and
detection.

**COE:** Central Office Equipment.

**Concentrator:** A switching device that provides access between a
larger

number of ports or lines and a smaller number of paths or trunks.

**Controller:** A unit that interprets and acts on coded instructions.

**DAMA:** Demand Assignment Multiple Access; access from many sources or

locations upon request (demand). Also see TDMA.

**DC:** Direct Current.

**DS1:** Digital Signal at the First level, 1.544 megabits per second.

**DSX1:** A DS1 interface or crossconnect point.

**FAA:** Federal Aviation Administration, a U.S. Government Agency.

**FCC:** Federal Communications Commission, a U.S. Government Agency.

**FDM:** Frequency Division Multiplex; multiplex by discrete frequency
assignment

of channels.

**FDMA:** Frequency Division Multiple Access; access from many sources
or

locations on a frequency division basis. Also see DAMA and FDM.

**ABBREVIATIONS & DEFINITIONS - Continued**

**GHz:** Gigahertz, one billion cycles per second.

**kHz:** Kilohertz, one thousand cycles per second.

**LPC:** Linear Predictive Coding, a digital coding technique.

**MSA:** Metropolitan Statistical Area.

**MHz:** Megahertz, one million cycles per second.

**Processor:** See Controller.

**Repeater Radio Station:** All equipment located at the BETRS radio
repeater

site. (FCC term: Relay Station.)

**RSA:** Rural Service Area; geographic areas designated by the FCC for
cellular

radio service in nonmetropolitan areas.

**Subscriber Radio Station:** All equipment located at the BETRS
subscriber

radio terminal site. (FCC term: Rural Subscriber Station.)

**T1:** A digital transmission system operating at DS1.

**TDM:** Time Division Multiplex; multiplex by discrete time assignment
of

channels.

**TDMA:** Time Division Multiple Access; access from many sources or
locations on

a time division basis. Also see DAMA and TDM.

**Yagi:** A type of directional antenna.

**1. OVERVIEW**

**1.1 [General]{.underline}**

**1.1.1** This bulletin provides borrowers of the Rural Electrification
Administration (REA) and other interested parties with technical
information on Basic Exchange Telecommunications Radio Service (BETRS).
BETRS is a public telecommunications Rural Radio Service used as an
alternative to traditional telecommunications outside plant, carrier and
radio facilities. The information and recommendations in this bulletin
are advisory.

**1.1.2** BETRS was established by the Federal Communications Commission
(FCC)

in December 1987. FCC Rules concerning BETRS and other radio equipment
and services are contained in the Code of Federal Regulations, Title 47.
BETRS History is summarized in Appendix 1. This bulletin addresses BETRS
in the

150 and 450 MHz bands that have co-primary status (primary and equal)
with

the Public Land Mobile Service and the 800 MHz band that has co-primary
status with the Private Land Mobile Service (also called Specialized
Mobile Radio Service or SMRS). BETRS in the 800 MHz Cellular Radio band
is not covered

in this bulletin. A discussion of Cellular Radio Systems is planned for

Bulletin 1751H-705.

**1.1.3** As a background for BETRS, this bulletin begins with a brief
overview of subscriber radio equipment available for rural
telecommunications service. Section 2 provides a description of the
BETRS concept, existing analog equipment, and evolving digital
equipment. Section 3 provides BETRS application guidelines with
discussion on preliminary planning, radio system design, FCC Radio
Station Authorization, specification considerations, system proposals,
and system implementation. Generic descriptive terms are used to
describe radio systems and equipment throughout this bulletin except
that paragraph 3.5 uses FCC terms in discussing the FCC Radio Station
Authorization.

**1.1.4** While this bulletin is intended to aid REA borrowers in the
design, procurement and implementation of BETRS for rural
telecommunications service, it is not intended as a complete reference
on BETRS radio system design. Specialized knowledge and reference
material are required to design radio systems. This bulletin merely
highlights selected aspects of radio system design which are key to
adequate telecommunications service, approvals and conformance to
requirements of the REA, FCC, and other local, state, and national
organizations. Some material in this bulletin is abbreviated to reduce
volume.

**1.1.5** As reference material is subject to change, the latest issues
of source reference documents should be obtained, reviewed, and
addressed. The discussion and explanation of outside references
contained in this bulletin serve as a guide, but may be outdated because
of changes in source references. For instance, the latest FCC Rules
should be addressed in FCC license applications. Electrical codes are
periodically revised and code requirements may vary with localities.

**1.1.6** In the past, BETRS type subscriber radio service was sometimes
provided as a part of Improved Mobile Telephone Service at 150 and 450
MHz. Presently, BETRS is usually provided as a service that is separate
from mobile service in

these bands. The ultimate goal is BETRS equipment that is universal in
application and interface, designed for economical point-to-multipoint
demand assess (trunked) applications, packaged for easy installation,
and available with model variations for special applications and
features.

**1.1.7** A trunked radio system where channels are available by demand
assignment multiple access (DAMA) permits a limited number of radio
frequencies and channels to serve a larger number of separately located
telecommunications subscribers. This bulletin emphasizes equipment
designed for point-to-multipoint application utilizing frequency
division multiple access (FDMA), time division multiple access (TDMA),
and combinations of FDMA and TDMA.

**1.2. [Subscriber Radio Equipment]{.underline}**

**1.2.1** The following is a summary of subscriber radio equipment used
or available for rural telecommunications service.

1\. Point-to-Multipoint (150, 450 and 800 MHz BETRS)

2\. Point-to-Multipoint (2 GHz by FCC Waiver)

3\. Point-to-Multipoint (800 MHz Cellular)

4\. Point-to-Point (2 GHz and Other)

5\. Point-to-Point (150 and 450 MHz BETRS)

**1.2.2** Point-to-multipoint BETRS trunked radio equipment at 150, 450
and 800 MHz can be used to serve individual telephone subscribers from a
common location on a demand access basis (Figure 1). A radio system with
channels available by demand access is referenced by the FCC as a
\"trunked\" radio system. Point-to-multipoint subscriber radio equipment
has been available on the world market for several years. The BETRS
action by the FCC prompted interest in the U.S. market. Some
manufacturers developed new digital radio equipment and others used
existing analog radio equipment to address this market. BETRS equipment
is covered by Part 22 of the FCC rules.

**1.2.3** Point-to-multipoint trunked radio equipment at 2 GHz is also
used to

serve individual subscribers from a common location on a demand access
basis. One type of this equipment has been used in various parts of the
world for over 10 years, and has successfully completed two REA field
trials. FCC licenses were obtained by waiver because this equipment is
not licensed in the common carrier band. The waiver process is often
difficult and lengthy, and waivers to use this equipment have been
denied since the BETRS authorization.

**1.2.4** Point-to-multipoint trunked radio service in the 800 MHz
Cellular Radio band is also available. Fixed subscriber service in the
Cellular Service band was not addressed in the original FCC BETRS
action. Cellular Rural Service Areas (RSAs) have been licensed by the
FCC, and BETRS fixed service was permitted on a Secondary basis in a
January 1989 FCC Order and further relaxed in a February 1990 FCC Order.
BETRS is Secondary to cellular mobile service in this band. However, the
cellular licensee has a reasonable degree of freedom in providing BETRS
fixed service so long as the mobile service needs

are adequately met. BETRS in the Cellular Radio Service band is
mentioned for completeness, but will not be addressed in this bulletin.
Cellular radio equipment is covered in Part 22 of the FCC rules.

**1.2.5** Point-to-point microwave radio equipment is used to serve
remote subscriber clusters (Figure 2). The most popular arrangement is 2
GHz digital radio equipment with 96 or 192 voice channels. From the
remote radio equipment, subscribers are served with conventional
telephone cables, or from digital subscriber carrier equipment extended
over T1 span lines from the remote radio terminal. This digital radio
equipment is covered by Part 21 of the FCC rules.

**1.2.6** Point-to-point BETRS analog and digital radio equipment at 150
and 450 MHz is used to serve remote subscriber clusters. This is
illustrated in Figure 3 and is similar to the point-to-point microwave
radio illustrated in Figure 2, except that two or more radio channels
are used to serve a nearby subscriber cluster.

**1.2.6.1** Point-to-point analog radio equipment at 150 and 450 MHz is
also used to serve individual subscribers on a dedicated channel basis
(Figure 4). This equipment has been available in the past as \"rural
radio\" or \"line extender radio.\" It was licensed under FCC Part 22
Public Mobile Service as secondary service. The BETRS action by the FCC
upgraded this application to co-primary status under FCC Part 22. Rural
radio equipment is useful in select or small startup applications.

**1.2.7** The radio service tools described above are presently
available to REA borrowers. REA recommends the use of equipment that is
most suitable and economical for the specific application. The balance
of this bulletin will emphasize BETRS trunked radio equipment with
demand access channels for point-to-multipoint service in the 150, 450
and 800 MHz bands.

**2. BETRS EQUIPMENT AND SYSTEMS**

**2.1 [Introduction]{.underline}**

**2.1.1** [B]{.underline}asic [E]{.underline}xchange
[T]{.underline}elecommunications [R]{.underline}adio
[S]{.underline}ervice or [BETRS]{.underline} was established by the FCC
in December 1987. BETRS is a public telecommunications rural radio
service used as an alternative to traditional telecommunications outside
plant facilities. Co-primary status is provided for BETRS in the
following bands.

[Frequency]{.underline} [Channels]{.underline} [BETRS]{.underline}
[Co-Primary Service & FCC Rules]{.underline}

150 MHz 18 Part 22 Public Land Mobile - Part 22

450 MHz 26 Part 22 Public Land Mobile - Part 22

800 MHz 50 Part 22 Private Land Mobile - Part 90

**2.1.2** Some restrictions apply. For example, the FCC requires 800 MHz
BETRS to be at least 100 miles from the border of the 54 largest
Metropolitan Statistical Areas (MSAs). BETRS eligibility is limited to
local exchange carriers and others with state authorization (where
applicable). Cellular radio was not addressed in the original BETRS
authorization, but was addressed

in later FCC Reports and Orders concerning cellular systems. Cellular
operators and resellers so authorized by their state regulatory entities
may offer fixed BETRS in RSAs and rural parts of MSAs.

**2.1.3** BETRS equipment is basically radio equipment that is
substituted for traditional telecommunications facilities, including
copper cable, carrier,

lightwave and microwave radio systems. The BETRS equipment provides
standard services and operates with standard telecommunications
equipment and interfaces. This includes central office equipment,
telephone sets, and other customer premises equipment meeting FCC Part
68; and standard voice and digital interfaces such as DS1. BETRS is
intended as a direct replacement for hard wire circuits where cost
effective.

**2.1.4** BETRS can be used for area coverage, or can be used to
supplement service by conventional facilities. In general, a mixture of
conventional facilities and BETRS may be more economical than an
all-BETRS design.

**2.1.5** The REA continues to seek technologies for cost effective
telecommunications service in rural areas. The use of radio to provide
telephone service to subscribers in rural areas met with limited success
prior to BETRS. With the FCC licensing of frequencies on a co-primary
basis, the use of BETRS radio equipment is expected to increase. BETRS
radio equipment can be used in conjunction with traditional
telecommunications equipment and facilities to provide more cost
effective service to subscribers.

**2.1.6** The BETRS frequency allocation provides for a total of 94
radio channel pairs (94 base transmit channels and 94 subscriber
transmit channels) in three radio frequency bands. Many of the 44 radio
channels at 150 and 450 MHz may be in use for public mobile service; and
the restrictions for the 50 radio channels in the private mobile service
may limit their application. Radio spectrum efficiency will be necessary
for maximum rural area coverage.

**2.1.7** The spacing between radio channels is 25 kHz at 450 and 800
MHz, and

30 kHz at 150 kHz. This provides a maximum radio channel bandwidth of 25
kHz (or 30 kHz) with a usable bandwidth of less than 25 kHz. Radio
channels are sometimes subdivided by using time division multiplex (TDM)
or frequency division multiplex (FDM) to achieve two or more voice
channels for each 25 kHz radio channel.

**2.1.8** BETRS radio equipment and systems are evolving. Systems
illustrated in the following paragraphs are representative of present
equipment. However, all parts of the illustrated systems may not be
available from one manufacturer at this time.

**2.2 [BETRS Equipment Description]{.underline}**

**2.2.1** **[Point-to-Multipoint Systems]{.underline}:** A basic
point-to-multipoint BETRS radio system consists of a base radio station
and a number of subscriber radio stations located at or near individual
subscribers (Figure 1). An example of a BETRS service area using
point-to-multipoint radio equipment is illustrated in Figure 5. The base
station may be co-located with the central office (CO) switch, or
remotely located and connected via trunk facilities such as digital
carrier.

**2.2.2** **[Base Radio Station]{.underline}:** A typical base radio
station is illustrated in Figure 6. It consists of several radio
transmitters and receivers (often called transceivers), a combiner,
antenna, concentrator, codecs (coders and decoders), controller and
power supply. The combined signals of radio transmitters and receivers
are connected to an omnidirectional antenna. The number of radio
channels required is determined by the number of subscribers and
expected system use (traffic). For this illustration, three radio
channels are shown for service to a larger number of subscribers. The
subscriber lines are concentrated into three trunks or radio channels.
The assignment of subscribers and radio channels is handled by a
processor or controller through a concentrator. This action is similar
to that of establishing a call through a central office switch. For
incoming and outgoing calls, all radio subscribers have access to all
idle trunks on a demand basis (trunked radio system).

**2.2.2.1** Power for the base radio station should be from a battery
source with sufficient capacity to provide for at least 8 hours standby
operation in the event of a commercial power failure. The battery supply
(nominal 50 volts dc) for the central office equipment is the preferred
power source for a

co-located base radio station.

**2.2.3** **[Modular Base Station]{.underline}**: The base station
should be designed in modules to provide for growth. Another important
reason for modular construction is to provide for separation of the base
radio transceivers from office equipment interfacing the CO switch. This
allows the radio transceivers to be located at the optimum antenna and
subscriber service location without regard to the CO switch location
(Figure 7). The concentrator might be at either the office or radio
location. With the concentrator at the office, the links between the
office and radio are trunks; with the concentrator at the radio, the
links are lines. Trunk links are more efficient (fewer circuits
required) and will be used for this discussion. The link between the
BETRS office equipment and the base radio station may be voice
frequency, carrier or radio circuits; but they are likely to be digital
carrier (DS1) over T1 type span lines or digital radio. The trend will
be toward standard digital interfaces (DSX1) for all BETRS radio
systems.

**2.2.4** **[Subscriber Radio Station]{.underline}**: The subscriber
radio station is illustrated in Figure 8. It consists of a radio
transceiver, a directional antenna (with transmit-receive combiner or
duplexer), a controller, codec and power supply. The subscriber radio
transceiver should be capable of transmitting and receiving on any
available channel on demand which requires a radio frequency
synthesizer. The subscriber controller receives instructions from the
base controller for channel assignment. The subscriber interface should
be a standard modular jack for use with customer premises equipment.

**2.2.4.1** Power for the subscriber radio station should be from a
battery source with sufficient capacity to provide for at least 8 hours
standby operation in the event of a commercial power failure. Small
rechargable batteries in the range of 12 to 24 volts are generally used.
Solar power with backup batteries are sometimes used for subscriber
station power.

**2.2.4.2** Access and use of commercial power at the subscriber
location require special attention. The telco may place the BETRS
equipment away from the subscriber\'s building and contract directly
with the local electric utility for electricity. The cost of electricity
at subscriber location should be considered in system economics. Another
option is to arrange for access to the radio subscriber\'s electric
power. This requires that special attention be given to national, state
and local electrical codes concerning power wiring and grounding. For
low power subscriber units, the use of Listed Class 2 transformers and
low voltage wiring may simplify installation (Listed by United
Laboratories or other similar type Listing agency acceptable to the
authority having jurisdiction). Radio station power consumption may
require negotiation with the subscriber for power costs.

**2.2.5** **[Repeater Radio Station]{.underline}**: A BETRS repeater
radio station can be used to extend service from the CO building to a
single base transceiver location in lieu of the office to base radio
station link described in paragraph 2.2.3. Repeater radio stations can
also be used to create multiple base transceiver locations to extend
service over a wider area (Figure 9). The use of BETRS repeaters can
increase the service area coverage, but may not be cost effective in
many applications.

**2.2.5.1** Two types of BETRS radio repeaters are discussed. The first
involves the retransmission of radio signals into a distant service area
using a new set of radio frequencies different from the basic service
area radio frequencies. The second involves the reuse of the same radio
frequencies as the base radio station to provide fill-in service into
shadow areas within the basic service area. For purposes of FCC radio
station authorization, a radio repeater requiring additional radio
frequencies is separately licensed as a \"relay station;\" and a radio
repeater that reuses the base radio station frequencies is considered
under the basic authorization. See paragraph 3.5 for additional
discussion on FCC authorization.

**2.2.5.2** Figure 10 illustrates the allocation of radio frequencies
for a three channel BETRS system in basic service. Figure 11 illustrates
a similar BETRS system using repeaters that require additional
frequencies. Three radio frequency pairs are required for the basic
system and three additional frequency pairs are required for the
repeatered system. The three frequency pairs (Tx1/Rec1, Tx2/Rec2, and
Tx3/Rec3) that link the base radio station and repeater radio station
can also be used to serve subscribers in the base station service area.
In an actual arrangement like this, it is likely that more frequency
pairs will be needed for the base radio station than the repeater radio
station. This is because the base serves all of the repeater subscribers
(through the repeater) in addition to the base subscribers.

**2.2.5.3** Back-to-back radio channels or heterodyne (frequency
conversion) techniques may be used to construct repeaters. Radio
frequencies may be limited. The use of repeaters may require increased
radio spectrum efficiency such as subdividing the 25 kHz radio channel
into multiple voice circuits.

**2.2.5.4** Another service possibility is to reuse the base and
subscriber radio frequencies by amplifying the radio signals at a
distant location. This type of radio repeater has been called a
\"booster\" or \"beam bender.\" This technique was previously used in
microwave radio with linear amplifiers and highly directive antennas.
Work is currently under way to use this technique

in BETRS and cellular radio systems. This type of repeater may prove to
be a cost effective method for fill-in service to shadow areas within
the basic service area that cannot be reached by the base radio station.
Because frequencies are reused and amplified, control of the repeater
service area and co-channel interference is essential to the
satisfactory application.

**2.2.6** **[Point-to-Point Systems]{.underline}**: Point-to-point radio
refers to a radio system application between two locations; the radio
system connects two points such as a central office switch and a
subscriber or cluster of subscribers. In this bulletin, a BETRS
point-to-point radio \"system\" refers to a system where multiple radio
channels are shared on a demand access basis (trunk to line
concentration) like point-to-multipoint BETRS systems. A point-to-point
application where each radio channel is dedicated to an individual
subscriber is called \"rural radio equipment\" (see paragraph 2.2.7).
Because BETRS radio frequencies are limited, channel sharing spectrum
efficiency is encouraged.

**2.2.6.1** A point-to-point BETRS radio system consists of several
radio channels between the central office and a remote subscriber
cluster location with an integrated concentrator. This allows a larger
number of subscribers to be served over a smaller number of trunks
(voice channels). Figure 3 illustrates the basic concept. Equipment for
both the base and remote radio stations would be similar to Figure 6
except that directional antennas would be used. Point-to-point BETRS
equipment may be a special arrangement of point-to-multipoint BETRS
equipment, or may be a separate unique system. Radio equipment and
integrated system design may permit radio frequencies to be shared by
point-to-point and point-to-multipoint systems.

**2.2.6.2** A subscriber cluster application might be engineered with
digital radio equipment as described in paragraph 1.2.5 and Figure 2; or
might be engineered using BETRS radio equipment at 150, 450 or 800 MHz.
The equipment choice will depend on the specific application. Larger
channel quantities and longer distribution lengths tend to justify
digital microwave radio equipment. Applications for small channel
quantities may justify the use of BETRS radio equipment, especially if
the cluster service is part of an overall distributed BETRS application
sharing radio frequencies.

**2.2.7** **[Rural Radio Equipment]{.underline}:** Rural radio equipment
refers to point-to-point radio equipment where each radio channel is
dedicated to an individual subscriber (Figure 4). The subscriber radio
station is located at or near the subscriber. The base radio station may
be located at the CO switch or at some point along the outside plant
route. Rural radio is useful in select or small startup applications.

**2.2.8** **[Radio Propagation Patterns]{.underline}**: Careful
selection of antennas and radio station locations can improve radio
system coverage, reduce interference, and minimize costs. Figure 12
illustrates some radio propagation patterns. The reference antenna for
radiation patterns and gain is called an isotropic antenna, which is a
theoretical point source in free space that radiates equally in all
directions. The isotropic radiator would produce a spherical pattern; it
is a theoretical antenna for reference purposes.

**2.2.8.1** An antenna consisting of a vertical pole on top of a tall
tower will radiate equally along the horizontal axis and produce a
circular pattern

(Figure 12A). This would be equivalent to a half wave dipole in free
space and provide a modest gain over the isotropic reference. This
vertical pole is generally referenced as an omnidirectional antenna,
radiating in all (horizontal) directions.

**2.2.8.2** An omnidirectional antenna in the real world will produce an
irregular pattern because of obstacles in the radiation path (Figure
12B). In a point-to-multipoint system, the central station or base
station antenna is generally placed on a tall tower or other point of
high elevation above the surrounding area to minimize the effects of
obstacles in the intended radiation path. This allows the many
subscriber station antennas to be placed on smaller towers, reducing
system costs.

**2.2.8.3** Directional antennas are used to focus the radiation pattern
into one or more directional patterns (Figure 12C). This focused
radiation or directivity provides effective gain in the intended
direction and minimizes interference in other directions. Directional
antennas are used at subscriber locations in BETRS systems. These are
generally Yagi antennas that produce about 10 dB gain over the isotropic
reference.

**2.2.8.4** In summary, BETRS systems generally use both omnidirectional
and directional antennas. The base radio station will generally use an
omnidirectional antenna, but may employ some directivity depending on
service area coverage requirements. The subscriber radio station is
required by the FCC to use a directional antenna which to reduce
interference. A repeater radio station will use a directional antenna
toward the radio base station; and will use an omnidirectional or
directional antenna toward subscribers depending on service coverage
requirements (Figure 11). The base radio station and repeater radio
station may use partially directive or highly directive antennas to
customize the service area coverage. A directional antenna at the base
radio station may eliminate the need for a repeater radio station.

**2.3 [Present Analog Equipment]{.underline}**

**2.3.1** Analog subscriber radio equipment in the 150 and 450 MHz band
has been available on the world market for many years. This equipment
ranges from simple dedicated channel rural radio equipment to more
elaborate multichannel demand access systems. Because of the past
\"secondary\" FCC licensing status, the primary market for this
equipment has been the world market with limited application within the
US. While the radio equipment can fill a service need, the installed
equipment may not meet traditional telecommunications network
transmission standards such as circuit noise, voice frequency response,
voice level stability, etc. It is important that the purchaser and
seller reach agreement on basic equipment and installed system
performance criteria before equipment is purchased.

**2.3.2** The radio frequency range of coverage is limited to
approximately line-of-sight and depends on factors such as radio
transmitter output power, receiver sensitivity and selectivity, antenna
type, and terrain. The limiting distance may be in the order of 10 to 40
miles, depending on the equipment and application. Power requirements
are cited at one watt to 70 watts; this is largely dependent on the
radio transmitter output power. Data transmission

capability is generally cited in the range of 1200 to 9600 baud. The
subscriber radio station of some models may be located at some distance
from the subscriber (up to 1500 ohms of cable plus a 400 ohm telephone
set).

**2.3.3** The dedicated channel rural radio equipment is generally a
small unit designed for indoor mounting. The subscriber unit may be a
desktop or wall mount unit. Typically, this equipment is powered
directly from commercial

ac power with battery backup. Simplicity and low startup costs are key
characteristics of this type of equipment. The installed equipment may
not meet some of the traditional telecommunications network transmission
standards such as circuit noise and voice frequency bandwidth.

**2.3.4** Multichannel trunked radio systems are often modular equipment
units designed for varied applications. Many equipment types can be
applied as dedicated channel rural radio applications, and in
multichannel demand access point-to-point and point-to-multipoint
applications. Repeaters are generally available; these are usually
back-to-back radio units. Outdoor housings are generally available for
repeaters and subscriber radio stations. Many systems provide two voice
channels within the allocated 25 kHz bandwidth by splitting the radio
spectrum into two 12.5 kHz radio channels. Privacy options are available
in some models by frequency inversion or scramblers. Conversation

privacy options are recommended for fixed station BETRS applications.
Optional compandors may be available in some models to reduce circuit
noise. Battery backup is recommended for all applications, and
especially where commercial ac power failure will affect more than one
subscriber.

**2.4 [Evolving Digital Equipment]{.underline}**

**2.4.1** The trend is toward the use of digital systems for
transmission and switching in the telecommunications industry. New
designs of digital radio equipment are being developed especially for
the BETRS market. Bandwidth efficient digital coding techniques such as
linear predictive coding (LPC)

and adaptive differential pulse code modulation (ADPCM) are being
employed

for radio spectrum efficiency. Where digital coding other than North
American standard 64 kb/s pulse code modulation (PCM) is employed within
the radio system, interfaces at voice frequency and standard 64 kb/s are
provided.

**2.4.2** Digital BETRS radio systems are evolving. The characteristics
cited are based on present equipment characteristics and tentative
specifications for new equipment. This equipment is expected to meet
telecommunications network transmission standards. Traditional
transmission measurement techniques are analog in nature and may not be
adequate to verify the transmission performance of some digital systems.
Such test equipment was intended for use on analog circuits and digital
waveform coding such as

64 kb/s PCM. New digital coding schemes are based on speech
characteristics

and some parameters cannot be verified with traditional measurement
techniques. Until new measurement techniques are developed, the
measurements can be supplemented by subjective conversation comparison
tests.

**2.4.3** Spectrum efficient digital codes in combination with time
division multiple access (TDMA) or frequency division multiple access
(FDMA) permit increased spectrum efficiency. FDMA and TDMA may be
combined to allow subscriber access to any time slot in any radio
channel, permitting maximum

efficiency (traffic capability). Spectrum efficiency may be essential
for larger systems, and where radio frequency availability is limited.
One manufacturer uses TDM to provide four voice channels within one 25
kHz radio channel. This system applied in the 450 MHz band will be used
to illustrate the TDM process and capability.

**2.4.3.1** The 25 kHz radio channel is modulated with a 64 kb/s signal.
Using TDMA, the 64 kb/s signal is divided into time slots for four
separate 16 kb/s channels. Each 16 kb/s channel is modulated with a
spectrum efficient digital coding such as LPC. Each 16 kb/s voice
channel can be accessed by any subscriber within the system on a demand
basis. One 16 kb/s channel is the system control channel. The control
channel is the system manager for subscriber access and channel
assignment. One radio channel provides three voice channels and one
control channel. Four radio channels provide 15 voice channels and one
control channel.

**2.4.3.2** Figure 13 illustrates TDMA. The base radio station transmits
a continuous signal on a radio channel that is divided into time slots
for four channels. Each subscriber can access any available time slot on
any assigned radio channel. Subscribers can receive and transmit in any
available time slot on any assigned channel. The subscriber radio
station transmits in synchronized bursts so that the radio signals from
several subscriber transmitters effectively merge the transmitted bursts
within time frames. Up to four subscribers can transmit in appropriate
time slots of one 64 kb/s radio channel. Each subscriber has access to
an idle channel or time slot on demand.

**2.4.4** The radio frequency range of coverage is limited to
approximately line-of-sight and depends on factors such as radio
transmitter output power, receiver sensitivity and selectivity, timing,
antenna type, and terrain. The limiting distance may be in the order of
10 to 40 miles, depending on the equipment and application. Digital
systems provide a degree of conversation privacy that is superior to
analog systems. Data transmission capability is generally cited in the
range of 1200 to 4800 baud. Subscriber radio station power requirements
range from about 20 watts idle to 70 watts in use. Solar power options
are generally available for repeaters and subscriber radio stations. The
subscriber radio station of some models may be located at some distance
from the subscriber (up to 1500 ohms of cable plus a 400 ohm telephone
set).

**2.5 [Transition Toward Future]{.underline}**

**2.5.1** The transition from secondary Rural Radio Service to
co-primary Basic Exchange Telecommunications Radio Service has been
relatively smooth. Manufacturers and operating telephone companies
experienced the usual amount of problems with the introduction of new
technology and equipment. Most problems were corrected and the BETRS
equipment is serving subscribers that might not otherwise receive
telephone service.

**2.5.2** As the BETRS \"get started\" phase nears an end,
manufacturers, telcos and REA need to assess how to move from selective
BETRS applications toward truly universal BETRS applications. How can
BETRS equipment become a more universal alternative to the traditional
telecommunications outside plant

facilities? To a large degree, BETRS is expected to follow a path of
universal acceptance similar to that of subscriber carrier equipment.
Subscriber carrier moved from a last resort facility to a preferred
facility over a period of about 20 years. This transition did not occur
by accident. It occurred through the work and actions of many people and
organizations.

**2.5.3** **[BETRS Wish List]{.underline}:** The following are suggested
as factors and improvements needed for widespread application and
universal acceptance of BETRS equipment as an alternative to traditional
telecommunications outside plant facilities.

**2.5.3.1** **[Reliability]{.underline}:** Equipment reliability will
improve with experience and quantity production. The goal is for a
service reliability near that of conventional plant facilities.

**2.5.3.2** **[Cost]{.underline}:** Equipment and installed system costs
should be reduced to compete with conventional plant facilities. Costs
should improve with quantity production, experience and product
evolution.

**2.5.3.3** **[Power]{.underline}:** Power consumption should be
reduced, especially at the remote subscriber location. Reduced power
consumption can improve initial installation costs and operating costs
at remote locations. For customer furnished power, the use of Class 2
energy limiting transformers and low voltage wiring can reduce
installation complexity and costs. Because some potential BETRS
subscribers have no commercial power or unreliable power, economical
solar power is a desirable alternative at remote locations.

**2.5.3.4** **[Size]{.underline}:** The equipment size should be
reduced, especially at the remote subscriber location. Custom integrated
circuits can be used to reduce the equipment size and power consumption.

**2.5.3.5** **[Housings]{.underline}:** Outside housings at subscriber
locations are necessary for universal acceptance. The housing design
should be small, blend with the surrounding environment, dissipate the
heat generated by the equipment and the sun, provide environmental
protection from the elements, and minimize infestation by insects.
Reduction of size and power consumption can lead to housing design
improvements.

**2.5.3.6** **[Installation]{.underline}:** Equipment installation at
remote subscriber locations should be simplified. Size, power
consumption and housings are factors that affect installation simplicity
and costs.

**2.5.3.7** **[Repeaters]{.underline}:** Low cost repeaters are needed
to increase the service coverage area and for fill-in coverage.

**2.5.3.8** **[Modularity]{.underline}:** Modular equipment components
can increase equipment application flexibility and minimize startup
costs for small systems. Modular equipment can be used to keep initial
quantities and costs low without sacrificing growth potential. Modular
equipment can reduce obsolescence by providing for system upgrades in
size, features, and services.

**2.5.3.9** **[Frequencies]{.underline}:** Last, but no small matter, is
radio frequency availability. With the potential for co-channel
interference at 150 MHz and

location restrictions at 800 MHz, the 26 channels at 450 MHz are the
primary BETRS radio frequencies. The 450 MHz channels are heavily
committed to mobile service in urban areas, and may not be available for
BETRS in nearby rural areas. The 450 MHz channels provide an excellent
opportunity to prove the technology and reach subscribers that would not
otherwise have telephone service, but these frequencies are not adequate
for widespread universal service. Manufacturers use spectrum efficient
techniques, but this can increase equipment costs and limit the market.
Dedicated blocks of frequencies are needed for BETRS to become a
universal cost effective service. Frequency blocks (with FCC
authorization) would permit the design engineer to choose time division
or frequency division multiplex to economically address specific
markets.

**3. BETRS APPLICATION**

**3.1 [General]{.underline}**

**3.1.1** BETRS equipment and BETRS applications should provide standard
telecommunications service that is equal to or better than wireline
service. The BETRS system should provide service that is transparent to
standard telecommunications interfaces and to the subscriber. This means
that the BETRS radio equipment and systems are substitutes for
conventional outside plant cables and carrier systems interfacing with
central office equipment, telephone sets, and other customer premises
equipment meeting FCC Part 68. BETRS equipment should provide some
remote testing capability to minimize travel to customer locations
scattered over a wide area.

**3.1.2** BETRS may be used for first time service to an unserved area,
or may be used to supplement or extend service within an existing
service area. For temporary or permanent service, BETRS radio should be
considered as an economic alternative to conventional telecommunications
cable and carrier to:

a\. Serve subscribers scattered over a wide area.

b\. Provide new service or upgrade multiparty service.

c\. Reinforce or replace existing plant.

d\. Reduce or eliminate subscriber held-orders.

e\. Serve uncertain growth areas.

f\. Fill temporary and emergency service needs quickly.

**3.1.3** BETRS radio equipment is the ultimate in \"movable
telecommunications plant.\" It can be used for temporary service,
permanent service, or to delay construction of conventional plant until
service needs are accurately identified. BETRS equipment can be removed
and reused as needs dictate.

**3.1.4** Telecommunications service should be provided by utilizing the
most cost effective facilities and technology. Economic planning
strategies should avoid an all or nothing approach. Economic studies
should begin with broad prove-in or breakeven determinations, and then
be refined to consider a mixture of facilities and factors such as
isolated pockets of subscribers and terrain. Economic studies should be
made on appropriate competitive facilities and equipment. When BETRS
radio is potentially competitive with other service techniques, it is
recommended that economic studies include mixtures of copper, fiber, and
radio facilities, and possibly the use of more

than one type of radio equipment. There is no magic formula for the
prove-in of BETRS radio equipment.

**3.2 [Equipment and System Characteristics]{.underline}**

**3.2.1** Presently available BETRS radio systems range from dedicated
channel analog point-to-point equipment and systems to trunked
multichannel digital point-to-multipoint systems. In general, this
discussion will emphasize universal application point-to-multipoint
systems (analog or digital) with some discussion of point-to-point
systems. Dedicated channel rural radio equipment is useful in select
applications. It is not considered a system design tool for universal
application and will be mentioned only briefly. The specific service
requirements will determine the most appropriate BETRS system

and/or equipment. The following components are used to describe BETRS
radio equipment and system characteristics.

[Base Radio Station]{.underline} is used to describe all equipment
located at the BETRS

central office radio terminal site. The FCC uses the term
[Central]{.underline}

[Office Station]{.underline}.

[Repeater Radio Station]{.underline} is used to describe all equipment
located at the

BETRS radio repeater site. The FCC uses the term [Relay
Station]{.underline}.

[Subscriber Radio Station]{.underline} is used to describe all equipment
located at the

BETRS subscriber radio terminal site. The FCC uses the term
[Rural]{.underline}

[Subscriber Station]{.underline}.

**3.2.1.1** The FCC terms will be used in paragraph 3.5 and the generic
descriptive terms will be used elsewhere.

**3.2.2** **[Point-to-Multipoint Systems]{.underline}:** A
point-to-multipoint radio system used to serve scattered individual
subscribers from a common location is illustrated in Figure 5.
Subscribers are served on a \"trunked\" basis where radio channels are
shared and idle channels are available on demand by any served
subscriber. All subscribers have access to any available channel.

The advantage of this equipment is versatility. It is nearly universal
in application. Common equipment costs are shared by a number of
subscribers, and economics may limit the minimum system size that is
cost effective.

**3.2.2.1** The base radio station equipment may be located in the
central office building, or at a location some distance away. Part of
the BETRS office terminal may be co-located with the central office
equipment (COE), with the remainder of the office terminal (i.e., base
radio) at a more appropriate radio service location. The two locations
are usually connected by T1 span lines or digital microwave radio
equipment. BETRS radio repeater stations can be used to extend service
from the central office building to a single repeater radio station
location or multiple repeater radio station locations to generally or
selectively expand the service area.

**3.2.3** **[Point-to-Point Systems]{.underline}:** A point-to-point
radio system used to serve

subscriber clusters on a shared channel basis is illustrated in Figure
3. The major advantage of this equipment is the shared common costs
associated with both the office and subscriber ends. This includes power
supplies, subscriber housings, etc. Several radio channels are used as
trunks for a larger number of subscriber lines. Concentration ratios are
determined by traffic requirements and system characteristics such as
local switching at the subscriber terminal.

**3.2.3.1** Point-to-point cluster service may be provided by separate
stand alone systems, or may be an option of point-to-multipoint systems.
A common base radio station and shared use of radio frequencies may be
practical with integrated point-to-point and point-to-multipoint
systems. Otherwise, separate radio systems and channels will be required
for each application, even with a common base station location.

**3.2.4** **[Rural Radio Equipment]{.underline}:** Point-to-point or
\"rural radio\" equipment is used to serve individual subscribers on a
dedicated channel basis. The major advantage of this equipment is the
low startup cost to serve one or several scattered subscribers. It is
similar in concept to the \"add-on\" one channel subscriber carrier.
Rural radio equipment consists of frequency mated office and subscriber
terminals. The radio frequency pair is preselected and fixed by the FCC.
In general, the frequency cannot be reused within an exchange area which
limits the growth capability. However, frequency reuse without
interference may be possible depending on the specific radio station
locations and directional antenna orientation. The office terminal may
be located at the central office equipment (COE) building, at the end of
a cable route, or other convenient location.

**3.2.5** **[Radio Repeaters]{.underline}:** Radio repeaters can be used
with any of the above terminal equipment to extend the area of radio
coverage as discussed in paragraph 2.2.5. This is accomplished by radio
frequency reuse within the basic service area, and by the use of
additional radio frequencies to serve areas beyond the basic service
area. System economics, radio frequency availability, and potential
co-channel interference will influence decisions concerning the use of
repeaters.

**3.2.6** **[Miscellaneous Considerations]{.underline}:** In the
planning and design of BETRS radio systems, factors such as loop length
from the subscriber radio station, power at remote terminal and repeater
locations, remote housings, equipment accessibility, installation, and
maintenance should be considered. Subscriber loop length may be short
for service to individual subscribers, but BETRS systems should be
capable of extended outside plant loops beyond the subscriber radio
station for cluster service applications. Reliable commercial ac power
should be the first choice for primary system power if it is available.
Solar power may be considered as an alternative for low power
consumption repeater and subscriber radio stations, but may be costly
for high power consumption units. Physical access is always important,
even the most reliable equipment.

**3.2.6.1** Only single party (private line) BETRS radio equipment is
considered. While it is possible for the BETRS equipment to provide
multiparty service, it is not recommended because of increased equipment
complexity and cost. Conversation privacy should always be a
consideration for fixed station BETRS applications. Privacy options are
recommended for analog systems. Digital systems provide a degree of
conversation privacy that is superior to analog systems.

**3.3 [Preliminary Planning]{.underline}**

**3.3.1** Preliminary planning should begin with an up-to-date area
coverage survey or similar subscriber survey. The planning and layout of
a radio system is often done in incremental stages. A radio propagation
study is essential. However, preliminary system and path planning should
be completed before the final radio propagation study is made. The
following is suggested. Identify known and potential telephone
subscribers in an exchange area or an overall service area. Is it
practical to reach all subscribers by radio from the central office
building or another common location? Is a radio tower already in place
at the central office or other location? Is there a hill or other point
of high elevation within the service area for the radio base station? If
the radio base station is placed at one of these locations, will some
subscribers be blocked because of terrain or manmade structures? What
are the alternatives (such as repeaters, multiple base stations, or
cable extensions) for serving those remaining hard-to-reach subscribers?

**3.3.2** Preliminary planning can be accomplished by using a common
sense approach. If a mobile radio system is already in place, it can be
used to estimate the service area coverage with a BETRS radio system. If
good to marginal service is available to all subscriber locations with
the mobile system, directional antennas on towers at subscriber
locations should provide improved service - with the same transmitter
power in the same radio frequency band. The new BETRS system may use
different frequency bands and lower transmit power than the existing
mobile system. These differences may alter the service coverage area.

**3.3.3** From topographical maps and visual inspection, pick a base
radio station location. Draw lines on the map from the base station to
(a) the more distant subscribers, and (b) the subscribers with obstacles
in the path. Either by sketch or by mental image, view some of the
potentially difficult paths. Allow for growth of vegetation and
potential building development. For example, would towers of 100 feet at
the base station and 40 feet at the subscriber locations provide a path
above the path obstacles? The object of this review is to identify
probable base station locations and to be relatively sure of adequate
radio propagation (preferably line of sight) to most potential
subscribers at an early planning stage. Figure 14 illustrates a
simplified profile view of the radio propagation path between a base
radio station and a subscriber station.

**3.3.4** Review the costs and construction ease or burden for providing
rural telecommunications service by using conventional facilities. Would
new construction be economical using telephone cable, optical fibers, or
digital microwave radio equipment? Is it possible or practical to apply
digital or analog subscriber carrier (including distributed carrier) to
existing cables? Consider the economics of using mixtures of BETRS and
conventional facilities.

**3.3.5** Power availability, cost and reliability at subscriber and
repeater radio stations are important considerations in the planning and
implementation of a BETRS system. Will commercial power be available,
reliable and reasonable in cost? Is solar power a practical alternative
to commercial power? Power for BETRS equipment should be considered in
system economic studies and reliability calculations.

**3.3.6** Review available BETRS equipment and compare with service
requirements. Can the available equipment provide for initial service
and projected growth? Will the system provide for traditional
telecommunications service and standards? BETRS may be the only
practical way to serve scattered rural subscribers.

**3.4 [Radio System Design]{.underline}**

**3.4.1** **[Overview]{.underline}:** During the system design and
implementation stages, compliance with building, safety and electrical
codes and approvals by REA, FCC, Federal Aviation Administration (FAA)
and others are necessary. The suggestions and illustrations provided
here are advisory. They serve only to illustrate the process of BETRS
implementation. Early in the implementation process, approvals are
required by REA for financing; by the FCC for radio station operation;
possibly by FAA for tower construction; possibly by the Bureau of Land
Management, U.S. Fish and Wildlife, and State Historic Preservation on
environmental impact; and by other organizations in the enforcement of
local, state and national codes. Part 17 of FCC Rules covers tower
height, lighting, painting and FAA notification. In planning tower
locations, be aware of nearby airports, landing strips, and flight
paths.

**3.4.1.1** REA approvals are required for:

a\. Equipment: REA Acceptance.

b\. Plans and Specifications: REA Form 397 or 398 with appropriate

attached specifications.

c\. Other stages of regulatory and financial approval.

**3.4.1.2** In general, BETRS equipment needs to be REA Accepted (shown
on the REA List of Materials or have REA Technical Acceptance).
Exceptions are equipment placed on an REA field trial or waiver provided
in special circumstances. The request for REA approval of Plans and
Specifications and the request for FCC approval for Radio Station
Authorization should occur at approximately the same time.

**3.4.1.3** It is suggested that point-to-multipoint BETRS systems be
designed for 99.9 percent availability. This permits a total down time
of 8.8 hours

a year to the average individual subscriber due to propagation
conditions and equipment failures. Circumstances may dictate other
design availability requirements.

**3.4.2** **[System Design Considerations]{.underline}:** A review of
the quantity and location of subscribers to be served is the first order
of business. Determine the most cost effective mix of BETRS and
conventional telecommunications facilities. Determine if individual
radio stations at each subscriber location is necessary, or if it is
practical to share subscriber radio stations at common locations.
Determine if cluster service to some or all subscribers is practical.
Shared subscriber equipment is generally more economical than individual
subscriber units. Determine if all subscribers can be served from one
base radio station. If not, determine base radio station locations that
minimize the number of base stations. Plan systems that eliminate or
minimize the use of repeaters.

**3.4.2.1** Determine the number of voice trunks and radio channels
required to serve the subscribers (traffic calculation). Some BETRS
radio systems require a radio channel for each voice trunk. Other
systems subdivide the radio channel to provide up to 4 voice channels
for each radio channel. Determine if the base radio station can be
located at or near the COE. If not,

determine the most appropriate method of providing circuits between the
COE and the base radio station (i.e., T1 span line, repeater radio
station, etc.).

**3.4.2.2** Determine the most appropriate power sources for subscriber
radio stations, repeater radio stations, and any base radio stations not
co-located with the COE. In general, this will be commercial ac power
contracted with the local power company or the subscriber being served.
AC power connections require that attention must be given to local,
state and national electrical codes for the safety of the general public
and telco employees. Power for the base radio station located at the COE
should be provided by the central office battery supply. Solar power may
be appropriate for repeater radio stations and subscriber radio
stations. Power consumption (idle and in use) and battery reserve
calculations (8 hours recommended) for all sites are needed.

**3.4.2.3** Electrical protection for equipment and safety of people
require special attention where antennas are located. Generally, the
higher the antenna above surrounding structures, the greater the
exposure to lightning, and the greater the need for low resistance
grounds and bonding connections. All exposed metallic surfaces (inside
and outside cabinets) within the area require common bonding and
grounding. Careful attention should be given to proper bonding and
grounding at digital COE buildings to minimize damage to sensitive
electronic equipment. The BETRS equipment manufacturer\'s
recommendations concerning safety and protection should be followed. The
manufacturer\'s recommendations should include surge protection for the
ac power connection, antenna, and equipment interfaces.

**3.4.3** **[Radio Propagation Study]{.underline}:** After the sites for
base radio stations are chosen (and radio repeaters if used), a radio
propagation study is needed for each base station. Actually, two types
of radio propagation studies are needed. A propagation study is required
for the FCC using the Carey Method in FCC Report R-6406 (Technical
Factors Affecting the Assignment of Facilities in the Domestic Land
Mobile Radio Service, by Roger B. Carey, June 24, 1964). A survey using
the Carey Method will show the general radio service area coverage and
radio interference. However, the Carey Method is intended for Mobile
Service with at least 90 percent coverage probability. An additional
propagation study will be needed for reliable BETRS fixed service.

**3.4.3.1** While BETRS is usually a point-to-multipoint application of
equipment

similar to mobile service, the subscriber stations are fixed. \"Carey\"
or \"Average\" coverage does not ensure that each BETRS subscriber will
receive reliable service. Therefore, the radio propagation study for
reliable BETRS should include a point-to-point propagation study
(similar to a point-to-point microwave path survey). A study of the path
propagation between the base radio station and each subscriber radio
station should be made. Requirements for base station antenna tower
height, radio transmitter power (and effective radiated power), and
individual subscriber station antenna tower height are determined from
the study. Figure 14 is a simplified profile view of a radio propagation
path. Factors such as earth curvature are not considered. For

information on radio propagation and path surveys, refer to engineering
textbooks and to REA TE&CM Section 932 (planned for conversion into

Bulletin 1751H-701).

**3.4.3.2** Horizontal or vertical antenna polarization can be used for
BETRS point-to-multipoint systems. Horizontal polarization for BETRS
will provide

some interference isolation from vertically polarized mobile system
antennas. However, omnidirectional radiation patterns are easily
obtained from simple vertically polarized antennas. Generally, BETRS
systems will use omnidirectional (or multidirectional) antennas for the
base radio station and directional antennas for the subscriber radio
stations. Antenna polarization may be either horizontal or vertical, but
need to be the same for both the base and distant ends of a system. The
antennas are included in the propagation study. FCC waivers are required
for omnidirectional antennas and for vertical polarization in BETRS
systems. Such waivers are routinely considered by the FCC, but waivers
need to be requested in the application.

**3.4.3.3** Questions about the radio propagation study and system
responsibility are often raised. Will the Purchaser or Seller make the
preliminary and/or final radio propagation study? In the case of
marginal or unreliable service, is the Purchaser or Seller responsible
for corrective action to achieve reliable service? The remedies and
responsibilities may be different for minor system alterations to reach
one or two subscribers than for major path and service problems found
after equipment has been installed. These remedies and responsibilities
should be clearly stated in the contract for BETRS. The contract should
be one for a \"Reliable System\" or \"Service,\" and not just a contract
for hardware. System reliability and service should be defined
quantitatively to the extent possible. System and service guarantees may
prove costly in some cases.

**3.5 [FCC Radio Station Authorization]{.underline}**

**3.5.1** BETRS is covered in Part 22 of the FCC Rules under the general
heading of Public Mobile Service. The FCC Rules require radio equipment
[Type]{.underline} [Acceptance]{.underline} (equipment manufacturer) and
a [Radio Station Authorization]{.underline} (telco) to construct and
operate a BETRS radio system. The applicant should be familiar with Part
22 of the FCC Rules and other referenced Rules and Reports. The
following briefly highlights some aspects of the procedure and
information required in the application.

**3.5.2** When the application is ready to be filed, a call to the FCC
Public Mobile Radio Branch may be helpful to clarify issues and avoid
processing delays. The applicant may wish to seek specialized assistance
and contract for filing the FCC application and search for available
BETRS frequencies. Currently, FCC submissions and applications that
require fees are filed with the Mellon Bank in Pittsburgh, Pennsylvania,
using FCC Form 155. Submissions with fees that are filed elsewhere are
returned to the sender.

**3.5.3** The Authorization process begins with FCC Form 401,
\"Application for New or Modified Common Carrier Radio Station
Authorization Under Part 22\" filed with the FCC by the telco. At
regular intervals, the FCC will issue public notice listings on
applications (and other matters) to allow the public an opportunity to
comment on FCC proposed actions. The Radio Station

Authorization permits the BETRS system construction to begin. It
specifies the construction start date and terms of the authorization.
When construction has been completed in accordance with the radio
station authorization, the licensee notifies the FCC on Form 489,
\"Notification of Status of Facilities.\" BETRS service can commence the
day that Form 489 is placed in the mail to the FCC. See 22.45 of the FCC
Rules for the License Period. Reply by the FCC is

not required. (FCC filings can be delivered to the FCC and receive a
stamped record copy.) If construction is not complete within the terms
of the authorization, the authorization will automatically expire unless
a time extension application (FCC Form 489) is filed and approved by the
FCC.

**3.5.4** **[FCC Application]{.underline}:** The Application for FCC
Radio Station Authorization consists of a completed FCC Form 401 with
attachments. Follow the instructions and furnish information
specifically as noted. Some information is to be provided on FCC Form
401 while other information may be provided as attachments. The waivers,
supplementary showings and other items discussed are routinely
considered by the FCC for BETRS authorization. However, waivers need to
be requested and required information furnished with the application.
Unless noted otherwise, the following discussion and comments apply to a
point-to-multipoint BETRS system application.

**3.5.4.1** The applicant should be familiar with FCC Rules contained in
Part 22. A selected sample is discussed below.

[22.15(b)(1)]{.underline}: Search and list all co-channel stations
within distances:

1-Way 35 MHz to 162 MHz 67 Miles

2-Way 152 MHz to 162 MHz 84 Miles

2-Way 450 MHz to 460 MHz 67 Miles

1 & 2-Way Above height/power limits 125 Miles

[22.15(b)(2)]{.underline}: Interference studies may be made one of two
ways:

1\. By using Class of station and Geographic separation listed in

22.502 and 22.503.

2\. Utilizing the Carey Method in FCC Report R-6406.

[22.16(a)&(b)]{.underline}: A showing is required for radio channels. A
maximum of

four radio channels is normally granted with each initial application,

and each application for additions to existing systems. An application

for more than four channels may be granted, but will require additional

coordination within the FCC and may cause delay in the authorization.

[22.108 & 22.110]{.underline}: Note antenna direction and polarization
requirements.

A fixed station is required to utilize a directional antenna with

horizontal polarization. Waivers are required for omnidirectional

base station antennas and for vertical polarization.

[22.600]{.underline}: Note that subscriber stations are generally
covered under the

base station authorization.

[22.609]{.underline}: Note the supplementary showing required with
applications for

rural radio (BETRS) facilities.

**3.5.4.2** [FCC Form 401]{.underline}: One Schedule A is required with
each Application. One Schedule B is required for each Antenna Location
(generally base station antenna locations). Schedule A is self
explanatory. All exhibits that are attached to the application are
listed on Schedule A (Item 22). The following examples of attached
exhibits are based on the information requirements of Schedules A and B.

[FCC Form 401 - Schedule A]{.underline}

[Item 20]{.underline}: If the application requests one or more
additional radio

channels for existing service, a loading study (traffic study) is

required.

[Item 21]{.underline}: If the application requests more than one radio
channel for new

service, a statistical survey or other showing is required.

[FCC Form 401 - Schedule B]{.underline}

[Item 29]{.underline}: If waivers are requested, the exhibit has to
specify the FCC

Rule(s) that apply and show good cause for each waiver requested. For

point-to-multipoint BETRS systems, waivers need to be requested for

omnidirectional base station antennas and for vertical polarization of

radiated signals (base and subscriber).

[Item 37]{.underline}: The height and power engineering data require
special attention.

Some data is required on FCC Form 401 and exhibits may be required for

other data. For example, 37(i) requires an exhibit if the antenna is

not mounted on top of the antenna structure. Often an existing antenna

structure will be used and the top of the structure is already used. An

omnidirectional or other radiation pattern can be obtained, but an

explanation is required. Effective radiated power and co-channel

interference also require attention.

[FCC Form 401 - Miscellaneous]{.underline}

Other attachments may also be required that are not specifically listed

on FCC Form 401. For example, 22.601(a)(4) should be addressed to state

that the applicant is authorized to provide BETRS (State certification

or other authorization). Also, 22.609(a) requires a supplementary

showing why it is impractical to provide the required communication

service by means of wireline facilities. If relay stations are required,

22.601(b)(1) requires a showing why it is impractical to achieve the

communications without relay stations (i.e., out of signal range of

central office station). The application for relay stations can be filed

with the BETRS application.

**3.6 [System Specifications]{.underline}**

**3.6.1** **[Plans and Specifications]{.underline}:** At this time, REA
does not publish specifications that are appropriate for BETRS equipment
and application, and none are known to exist in the public domain.
Appropriate specifications or benchmark references are needed for REA
Acceptance (Listing) of BETRS systems, and appropriate equipment and
application specifications are needed as

attachments to REA contracts for REA-financed BETRS purchases.
Appropriate portions of other specifications by REA, Bellcore, industry
and manufacturers are usually referenced by REA, telcos, engineers and
manufacturers. For example, Bellcore Generic Requirements for Basic
Exchange Radio Systems

(TA-TSY-000911) covers digital BETRS systems.

**3.6.2** For REA financing, BETRS systems should be purchased on REA
contract Form 397 (or REA Form 398) with appropriate specifications
attached to the contract. These performance specifications are developed
by the telephone company\'s engineer. REA Form 397e, Mobile and Fixed
Radiotelephone Specifications is useful as a guide (and only as a guide)
for BETRS performance specifications. Form 397e was intended as a mobile
radio system specification with possible incidental use of fixed rural
radio applications. It is outdated and incomplete as a BETRS system
specification. REA Form 397c, Design Specifications for Subscriber
Carrier Systems is also useful as a guide for BETRS performance
specifications. Selected portions of REA specifications such as PE-64a
(digital subscriber carrier) and REA Forms 397a through 397h might be
helpful to the engineer in developing BETRS specification attachments.
Portions of traditional telecommunications standards and manufacturers\'
specifications for BETRS radio equipment can also be used. Specific
target values and limitations should be stated in the contract. It is
important that all parties reach agreement on contract provisions before
the contract is signed.

**3.6.3** BETRS specifications should be realistic and provide for
reliable, high quality telecommunications service. In some cases,
compromises may be required. In time, traditional performance parameters
are expected to apply to BETRS without exception. Traditional
transmission measurement techniques may not be adequate to verify some
performance parameters of digital BETRS systems. Traditional
transmission measurement techniques are analog in nature and may not be
effective in testing new digital speech coding systems. In addition to
agreement on performance parameters, Purchaser and Seller agreement may
be needed on test techniques to verify performance.

**3.6.4** **[BETRS Performance Specifications]{.underline}** should be
separated into four parts as illustrated below.

Part 1: Basic BETRS System and Equipment Performance

Part 2: Installation and Acceptance Tests

Part 3: Detailed Purchaser\'s Requirements

Part 4: Seller\'s Proposal

**3.6.4.1** For the basic BETRS system and equipment performance
requirements, the format in REA Form 397e, Part I is suggested. Appendix
2 provides an example of BETRS equipment specifications (partial list
only) that might be attached to REA Form 397. Appendix 2 contains
portions of selected standards and specifications from several sources
including REA and the telecommunica-tions industry. If manufacturers\'
specifications are used, care should be taken to keep the specifications
generic to the Purchaser\'s needs and not favor one manufacturer or
equipment over another.

**3.6.4.2** Installation and Acceptance Requirements should follow a
format similar to REA Form 397e, Part II. The specific details of
installation and

acceptance test requirements need to be updated with special attention
given to both the office and subscriber locations. Proper bonding and
grounding of antenna, equipment, and power is required to meet
electrical and safety codes for the safety of people and protection of
equipment and property at subscriber locations. Proper bonding and
grounding are also important at locations of other modern electronic
equipment including digital central

office equipment. Careful attention should be given to antenna grounding
and connection to other grounds external to the central office building;
to the building entrance of ac power, telephone cables, and coaxial
cables from the antenna; and to bonding and ground connections within
the building. A suggested REA reference is \"Electrical Protection of
Electronic Analog and Digital Central Office Equipment\" currently
published as REA TE&CM Section 810 and planned for conversion into
Bulletin 1751F-810.

**3.6.4.3** Detailed Purchaser\'s Requirements should follow a format
similar to Form 397e, Part IIIA. These requirements should outline the
specific system and equipment needs for BETRS service, and contain
sufficient detail for a clear understanding of the Purchaser\'s
requirements. Purchaser requirements and Seller responsibilities should
be clearly stated in all parts of the Purchaser\'s specifications.

**3.6.4.4** Equipment and service requirements should be covered in
detail. General requirements and special requirements for business,
data, paystations and other special applications should be stated.
Outside plant loop resistance from subscriber radio stations should be
stated. (For total drop resistance, add 400 ohms for customer premises
equipment.) Major and minor alarm requirements for radio equipment and
related requirements such as power systems and tower lighting should be
stated.

**3.6.4.5** The BETRS performance specifications should contain a
Seller\'s Proposal Summary similar to Form 397e, Part IIIB. This should
summarize the Seller responses to Purchaser requirements and serve as a
quick reference check list that assures the Purchaser that the Seller is
proposing a complete system to fulfill the Purchaser\'s system
requirements. The Summary should contain a statement that the proposed
system meets all Purchaser requirements, or note specific exceptions to
Purchaser\'s requirements. The Summary should contain a checklist of
detailed attachments by the Seller in response to the Purchase
requirements.

**3.6.4.6** The Purchaser\'s Requirements and the Seller\'s Proposal
should each contain a Narrative. The Purchaser\'s Narrative should
describe the initial and ultimate (growth) requirements for the
equipment, system and service.

The purpose of the Narrative is to outline the Purchaser\'s plans so
that the initial equipment furnished under the contract can later be
expanded to ultimate service needs with minimal impact. The Seller\'s
Narrative should describe the proposed system(s), equipment, component
parts, accessories, options and necessary test equipment. The Seller
should also outline a plan for orderly growth from the initial
quantities of equipment to the Purchaser\'s ultimate system
requirements.

**3.6.4.7** The proposal should describe the options available to the
Purchaser if the FCC does not grant a radio station authorization, or
grants authorization for less than the number of radio channels required
for adequate telecommunications service (present and future traffic
requirements). A termination clause or fallback provision in the
contract may be advisable.

**3.7 [System Proposals]{.underline}**

**3.7.1** It is recommended that the Purchaser seek proposals from
several manufacturers (or Sellers) of BETRS radio equipment. Each Seller
proposal should be reviewed for responsiveness to the Purchaser\'s
contract provisions including the radio system plans and specifications.
The lowest cost proposal that is responsive to the contract provisions
should be selected unless there are valid reasons to select another
proposal. The following proposal items should be noted.

**3.7.2** Did the proposal respond to all contract provisions? Are some
responses vague or inconclusive? Did the Seller take exception to some
contract provisions? Are the exceptions logical? Are the excepted
contract provisions essential to the service requirements, or do they
substantially alter the service requirements or contract provisions? Is
this a responsive proposal?

**3.7.3** Does the proposal include adequate spare parts? Are the
warranty provisions reasonable? Is the Repair and Return policy
satisfactorily addressed? Has on-site and factory training been
addressed? Does system maintenance require special test equipment? Does
the telco have adequate general and special purpose test equipment for
radio system maintenance?

**3.7.4** Does the proposal include adequate documentation? The proposal
should include equipment installation, operation and maintenance
manuals, and final copies of drawings that outline selected options,
special features, or other provisions.

**3.7.5** Are the Seller\'s installation and test responsibilities
clearly stated? Are other responsibilities by the Purchaser and Seller
clearly outlined in the contract? Has the proposal reinforced the
responsibility provisions, or did the proposal raise questions in some
areas? If the radio system fails to provide the necessary service, are
the alternatives clearly stated? Does the Purchaser or Seller bear the
cost if additional equipment or more costly alternative equipment is
required for satisfactory operation? What limits are imposed on remedies
and alternatives?

**3.7.6** The Purchaser and Seller should reach agreement on all aspects
of the contract before it is signed. Minor problems can become major
problems when contract provisions are not clearly stated.

**3.8 [System Implementation]{.underline}**

**3.8.1** If the planning, system design, FCC application, and contract
provisions are thorough and complete, system implementation should be
relatively smooth. Installation should be coordinated with all parties
involved. The installer should be provided reasonable access to
buildings, facilities and equipment, and be provided reasonable
assistance by qualified telco personnel.

**3.8.2** Installation should be monitored by a qualified telco
representative. Care should be taken to ensure that contract provisions
are met and that the installation meets building, electrical, and safety
code requirements. Special attention should be given to bonding and
grounding at antenna locations, digital central office equipment
locations, subscriber locations, and commercial power connections.

**3.8.3** System installation should always include equipment and system
acceptance tests. Acceptance tests serve to demonstrate equipment
performance relative to contract provisions, and serve as a benchmark
for later comparison and troubleshooting. Acceptance tests should
include physical inspection, operational tests, and electrical tests
such as radio frequency transmit power, receive signal strength, bit
error rate, voice levels, noise and distortion. To the degree practical,
radio fade margin tests should be made on radio stations with marginal
receive levels.

**3.8.4** A properly designed and installed BETRS system should provide

telecommunications service that is equal to or better than wireline
service. The subscriber should not be able to distinguish between
service provided by BETRS radio equipment and traditional
telecommunications facilities.

**APPENDIX 1**

**BETRS HISTORY**

It has been technically and economically possible for decades to use a
radio circuit as a link between a subscriber\'s telephone set and a
telephone switching office. In many areas of the world outside the
United States, radio circuits are routinely used. Radio circuits are
used in such widespread regions as parts of Africa, Australia, Canada,
South America, and the Middle East. Radio links proved to be the
technology of choice for conditions such as large land masses, little or
poor telecommunications infrastructure, hostile environment, scattered
clusters of subscribers, and scattered individual subscribers. These
conditions are common in many parts of the world including the United
States, especially in the West, Midwest and Alaska.

Radio would seem a natural medium for serving rural telephone
subscribers. Radio has been used for rural telephone service, but on a
somewhat limited basis. Rural subscribers generally have access to
mobile dial radio service, and microwave radio equipment is often used
as a trunk or subscriber link for central offices or large clusters of
subscribers. However, the use of radio for telephone service to
individual fixed subscribers (wireless telephone loop) has been
infrequent.

Soon after the REA was authorized by Congress in 1949 to make loans for
rural telephone service, REA engineers investigated unique methods to
provide this service economically. Radio was one of the methods explored
for this service in sparsely populated rural areas. During the 1950s REA
provided small grants to fund the development of subscriber radio
systems. General Electric and Motorola provided single channel radio
links in the 150 MHz radio band at locations in Virginia and Alabama.
Raytheon developed a 6 GHz radio system that provided two multiparty
channels to serve a small cluster of subscribers. It was first used by
an REA borrower in northern Wisconsin.

Dial mobile radio systems in the 150 MHz band were also developed with
the aid of REA grants. This dial mobile service was used extensively and
was the forerunner to Improved Mobile Telephone Service and Cellular
mobile service. Service to fixed subscribers was permitted as secondary
to mobile service in this band.

In general, each of these subscriber radio systems might be described as
a technological success. However, none of the systems proved to be a
long term solution for telephone service in sparsely populated rural
areas. The basic impediments were economics and regulation.

Rural radio service to fixed subscribers has long been available on a
[secondary]{.underline} basis in the 150 and 450 MHz bands allocated for
Public Land Mobile Service [if no harmful interference]{.underline} is
caused to mobile service. FCC permission for fixed service was always
secondary to mobile service, and rural radio was viewed more as
temporary plant rather than permanent plant.

In the late 1980s, two Texas REA borrowers were confronted with
deteriorating outside plant serving some of their remote subscribers.
Replacing the existing outside plant with buried filled cable was
considered prohibitively expensive. Using radio links, while expensive,
was considered feasible if no

**APPENDIX 1 - Continued**

future changes were necessary. For good cause, the FCC will waive their
rules. The two borrowers requested that the FCC waive the rules and
grant them licenses in a geographically underused radio band different
from the secondary rural radio service band. They cited economic
hardship and the remote likelihood of the requested frequencies being
used for the intended service in that area. After due process, the FCC
granted a license by waiver to operate in the 2 GHz band.

In May 1985, the REA Assistant Administrator (Telephone) called on
members of the four national telephone associations to join in an ad hoc
task force to prepare a petition to the FCC. The National Rural Telecomm
Association, the National Telephone Cooperative Association, the
Organization for the Protection and Advancement of Small Telephone
Companies, and the United States Telephone Association agreed to
participate with REA. The objective was to eliminate the secondary
status and the need for individual waivers. The task force filed a
petition with the FCC in May 1986. The petition requested three changes
in the FCC rules for BETRS.

1\. Co-Primary status on unused frequencies.

2\. Access to 26 frequency pairs in the 450 MHz band.

3\. Set aside 2 MHz of the cellular radio reserve.

The FCC issued a Notice of Proposed Rulemaking (NPRN) on BETRS in

January 1987. The BETRS proposal received wide support including
Regional Bell Operating Companies and radio equipment manufacturers. In
December 1987, the FCC adopted the Report and Order establishing BETRS,
and then published a Final Rule in February 1988. Co-primary status was
provided for BETRS in the following bands.

[Frequency]{.underline} [Channels]{.underline} [BETRS]{.underline}
[Co-Primary Service & FCC Rules]{.underline}

150 MHz 18 Part 22 Public Land Mobile - Part 22

450 MHz 26 Part 22 Public Land Mobile - Part 22

800 MHz 50 Part 22 Private Land Mobile - Part 90

Some restrictions apply. For example, the FCC requires BETRS at 800 MHz
to be at least 100 miles from the 54 largest Metropolitan Statistical
Areas. The BETRS authorization provides for a total of 94 radio
channels. Many of the

44 radio channels at 150 and 450 MHz may already be licensed for nearby
public mobile service; and the restrictions for the 50 radio channels in
the private mobile service may limit their application. While the
requested 2 MHz cellular reserve spectrum was denied, the FCC indicated
that if the allocated spectrum at a later time was insufficient,
additional spectrum would be considered.

In October 1988, the FCC adopted a BETRS provision in the cellular
service band. The FCC Order included, \"In the Domestic Public Cellular
Radio Telecommunications Service, this service provides public message
communication service to fixed subscribers in Rural Service areas and
rural parts of Metropolitan Statistical Areas.\" In the cellular band,
the FCC license is

awarded to cellular system operator. This requires the telco wishing to
provide BETRS in this band to be the cellular licensee or negotiate with
the cellular licensee for frequency spectrum.

**APPENDIX 1 - Continued**

**EPILOG**

The January 1987 BETRS authorization provided an opportunity to provide
service in rural areas on a \"permanent\" basis. BETRS will be of
limited value in certain regions because of limited radio channel
availability and restrictions. Even in less populated areas, radio
spectrum efficiency will be necessary for maximum rural area coverage.
The October 1988 Cellular BETRS authorization provided additional
potential for BETRS in rural areas. Cellular Rural Service Areas are
being licensed at the time of this writing. However, rural cellular
systems have not yet been constructed and placed into operation. It is
too soon to judge the degree or timetable that cellular radio will fill
this need in rural areas, especially in less populated areas.

Petitions for Reconsideration of the original BETRS Report and Order
were filed by Pacific Bell, Nevada Bell and the United States Telephone
Association. The petitions requested several changes including
additional spectrum and a liberal waiver policy for BETRS applicants to
ease restrictions on the present BETRS spectrum allocation. The liberal
waiver policy would permit broader application of the existing BETRS
allocation. Additional spectrum and especially discrete spectrum
permitting dynamic bandwidth allocation schemes would encourage
economical radio system design and universal systematic BETRS
applications.

The Request for Reconsideration was denied by the FCC in May 1989. The
FCC indicated that the need for reconsideration had not been established
by the Petitioners.

Through BETRS, the FCC has provided a means to serve subscribers in
rural areas on a \"permanent\" basis. This is an opportunity to get
started with BETRS. The need for additional spectrum and waivers will
have to be demonstrated. Additional frequency spectrum with dedicated
blocks of frequencies will be needed for BETRS to become a universal
cost effective service. Dedicated frequency blocks would permit the
radio manufacturer\'s design engineer to choose time division or
frequency division multiplex to economically address specific markets.

**APPENDIX 2**

**EXAMPLE OF BETRS EQUIPMENT SPECIFICATIONS**

This Appendix provides an example of BETRS equipment specifications
(partial list only) that might be attached to REA Form 397. It is
essentially a combination of selected standards and specifications from
several sources including REA and the telecommunications industry. Care
should be taken to keep the specifications generic to the Purchaser\'s
needs and not favor one manufacturer or equipment over another.

**[1. GENERAL]{.underline}**

**1.1** Equipment interfaces to the telecommunications network,
equipment, and

facilities shall conform to traditional telecommunications analog voice

frequency and signaling standards, or to D4/DS1 digital standards.

**1.2** The equipment shall be designed for proper operation and
interface with

customer premises equipment registered under FCC Part 68. Customer

premises equipment and material shall meet the Listing requirements of

national and local codes.

**1.3** The equipment shall be Type Accepted under FCC Part 22 and other

applicable FCC requirements. Specific FCC Acceptance Designations

shall be stated.

**1.4** The radio equipment shall return to an on-hook condition (a) if
the

receive level falls below the minimum service threshold for more than

five seconds; (b) within 5 seconds of subscriber or central office

disconnection; or, (c) within one minute for calls not completed.

**[2. ENVIRONMENT]{.underline}**

**2.1** Equipment mounted inside buildings shall operate satisfactorily
within

an ambient temperature range of 0° to 50°C and at 80 percent relative

humidity between 10° and 40°C. Equipment mounted outdoors shall operate

satisfactorily within an ambient temperature range of -40° to 60°C and
at

95 percent relative humidity between 10° and 40°C.

**2.2** DC powered equipment shall operate satisfactorily over a range
of 44 to

56 volts unless stated otherwise. AC powered equipment shall operate

satisfactorily over a range of 108 to 132 volts unless stated otherwise.

AC powered equipment shall be equipped with battery backup for a minimum

of eight hours operation.

**2.3** Power requirements shall be stated by the Seller at 50 volts dc
or

120 volts ac input for minimum power conditions (low traffic or standby)

and for maximum power conditions (high traffic, ringing, or in use).

**2.4** Outdoor equipment housings shall be of rugged construction,
corrosion

resistant, and water tight or weather resistant to provide proper

electrical and mechanical performance, protect the equipment from damage

or faulty operation due to moisture, dust and other airborne particles,

and minimize infestation by insects.

**APPENDIX 2 - Continued**

**[3. VOICE FREQUENCY]{.underline}**

**3.1 Impedance:** 2-Wire: 900 Ohms.

4-Wire: 600 Ohms.

Minimum Return Loss:

From CO End: 18 dB ERL; 12 dB SRL.

From Subscriber End: 16 dB ERL; 10 dB SRL.

**3.2** 1004 Hertz Loss: Set at 2 dB; 1.0 dB Maximum Variation, Long
Term.

Level Tracking: 0.5 dB Maximum Variation, From +3 to -37 dBm0 Input.

1.0 dB Maximum Variation, From -37 to -50 dBm0 Input.

Frequency Response Relative to 1004 Hertz:

+1 to -1 dB Maximum Variation, From 600 to 2400 Hertz

+1 to -3 dB Maximum Variation, From 300 to 3200 Hertz

-20 dB or Lower at 60 Hertz.

**3.3** Circuit Noise: 20 dBrnC Maximum (Operational).

Signal to Noise: 33 dB Minimum, From +3 to -30 dBm0 Input.

(Quantizing 27 dB Minimum, From -30 to -40 dBm0 Input.

Distortion) 22 dB Minimum, From -40 to -45 dBm0 Input.

Circuit Balance: 60 dB Minimum (ANSI/IEEE 455-1985).

Channel Crosstalk Loss: 65 dB Minimum.

**3.4** Voiceband Data: 2400 Baud Minimum (4800 Baud Objective).

**[4. RADIO FREQUENCY]{.underline}**

**4.1** General: RF Channels Required
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Maximum Bit Error Rate
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Maximum Path Loss in dB
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**4.2** Base Station: Transmit Frequencies
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Transmit Power Output (Per RF) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Effective Radiated Power (Per RF) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Minimum Receive Level
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Receive Level Range (Min to Max)\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Adjacent Channel Receive Rejection \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Co-Channel Receive Isolation \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Transmit to Receive Isolation \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**4.3** Subscriber Stations: Transmit Frequencies
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Transmit Power Output (Per RF) \_\_\_\_\_\_\_\_\_\_\_\_

Effective Radiated Power (Per RF) \_\_\_\_\_\_\_\_\_

Minimum Receive Level \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Receive Level Range (Min to Max)\_\_\_\_\_\_\_\_\_\_\_

Adjacent Channel Receive Rejection \_\_\_\_\_\_\_\_

Co-Channel Receive Isolation \_\_\_\_\_\_\_\_\_\_\_\_\_\_

Transmit to Receive Isolation \_\_\_\_\_\_\_\_\_\_\_\_\_

**4.4** Repeater
Station(s):\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Pages 33 - 39 Contain Figures 1 - 14

(These figures are available in hard copy only)