communications faq

7/31/2019 Communications FAQ

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rvival Communications FAQ Version 1.11

SCLAIMER: The authors and editors of this FAQ panel assume no

gal responsibility for any errors in or misuse of this information,

d are not to be held legally liable or responsible for any death,

jury, loss of property, or other negative consequences resulting

om use, misuse, or abuse of this information.

is document was written mainly by several long-time lurkers on

e usenet newsgroup misc.survivalism, in conjunction with me.

y comments should be sent to me at [email protected], and will be

ted on or forwarded to the author as appropriate.

is document is being archived at:

tp://www.idir.net/~medintz/surv_faq/comfaq11.txt

chiving or re-distribution is permitted only according to the

rms of the document http://www.idir.net/~medintz/disclaim.txt. In

neral, redistribution, use, or storage is approved, but there are

rtain stipulations and exceptions in that document that must be

eyed. (This condition may be over-ruled by the original author(s)

any time; should they wish to do so they should contact me privately.)

is document is a work in progress. Suggestions, comments, and

commendations are always welcomed, and will be acted on or

rwarded as appropriate.

rther information on radio may be gathered from 'The ARRL Handbook'

d the 'ARRL Operating Manual', published by the American Radio

lay League(http://www.arrl.org)

topic as broad as communications can never been completely covered,

pecially in what should be a terse and matter-of-fact FAQ. We'll

art out with the most general description we can provide, and get

re specific deeper in the document.

WHAT IS COMMUNICATION ?

e first step in understanding communications in the context

survival is understanding of the fundamentals of communication

self. Communication is a very complex topic, as difficult

completely define as truth, beauty, or time; however, in an

tempt to cut to the chase and make our life simple, we'll start

th two definitions:

MMUNICATION is the successful transfer of information from one

rson to another person or entity.

MMUNICATION SYSTEMS are comprised of equipment, methods and

chniques of supporting information transfer, enabling communication

take place between two people. (Please note that these definitions

e cheap outs, since we haven't defined what we mean by information,

t you get it, right? Note that we re also limiting things by

quiring at least one person in to loop, to reduce the scope of

is document.)

at Happens When We Communicate?

order for any communication to take place, there are three major

quirements that must satisfied.

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QUIREMENT ONE: There must be a sender and a receiver. For most

rvival purposes, this means a person trying to send a message and

person looking for a message sent to them.

QUIREMENT TWO: The sender and receiver must understand how the

ssage is to be conveyed, and must understand the message itself.

the survival context, this means that both people trying to

mmunicate understand how their communication system works (how to

erate the communications equipment, that one or two lamps have

fferent meanings, how to look up a word in a dictionary) and that

ey understand the message (the message in clear and in a common

nguage, that one lamp means that the British are coming by land

d two lamps means by sea.)

QUIREMENT THREE: the communication system must be capable of

livering the message. (There's not so much fog the lamps can't be

en, or that the radios are within range and working properly.

E ONE RULE OF COMMUNICATIONS: To communicate, the sender creates a

ssage that both he and the receiver should understand. Then, using

common system that is capable of delivering the message, the sender

ansmits the message to the receiver, who understands the message

nt.

RVIVAL IMPLICATIONS

ilure to communicate is always the result of a failure to meet the

quirements. A few specific examples:

e first requirement being that there is someone trying to send a

ssage and someone expecting to receive it may at first seem obvious,

wever in practice it is probably the most violated requirement of

mmunications in a survival context, providing the violator with a

lse sense of security until they need to communicate. For some

ason, somebody buys a CB and thinks they can be in the middle of

where, call for help on channel 9, and Air Rescue magically appears

come in and save them. Yup, it's a long day in hell when this happens.

's not just CB owners, either: this requirement gets violated by

ateur radio operators (I'll just call for help on the repeater

cept they left the directory home and their rig doesn't provide

e right sub-audible tones, or the guy that just answered your CQ

SOS on 40 meters thinks you're a crank) and Cell Phone users

hadda ya mean they don't have service in the middle of a wilderness

ea or during a massive power outage?).

r is this limited to radio: flare guns (It's 2AM, a bear just ate

ur camp partner, and you're fifty miles from civilization in a

lley. Shoot a flare off, and you've made your camp brighter for a

w seconds and pissed off the bear. Feel better?) Air horns (same

enario, maybe the bear leaves if it's loud enough.)

solving problems surrounding the first requirement simply means

king sure there is a person listening. Perhaps someone you know,

rhaps not. The 911 system, for example, consists of people

ntinually monitoring a phone for incoming messages from senders.

rld-wide, satellites and many pilots listen to 121.5 Mhz on their

dios, looking for distress signals. If a CB operator knew someone in

e area who agreed to listen on channel 9 for 15 minutes at 6PM

eryday, his chances of being heard then are vastly improved. The

m, who had punched in the frequency to his club's repeater, which

s a long-tone-zero (LTZ) emergency alert system that gets friends




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om the club on would be in better shape too; and if the ham's friend

s listening at 6PM everyday on 40 meters, it's doubtful his friend

uld think he was nuts if he said he needed help urgently. Having a

iend look for a flare on a ridge line a hour before sunrise--and

imbing to the ridge line to fire the flare--would work wonders,

o.

te that in each of these cases, not only was someone listening,

t there was coordination, also, in that the recipient of the messages

ew when and where to look or listen.

at have we learned?

Someone has to Send and someone needs to Listen.

Both have to use the same system. Both need to understand the message.

Coordination between the sender and listener vastly increases the

kelihood of successful communications.

A. Types of communications

Wired Communications

Basic Telephone Servicerrent telephone communications, at least in industrialized

tions, is the standard of excellence that most communications

stems are compared. Disparaging comments and annoying customer

rvice issues aside, standard phone service is nearly universal,

proaches 100 percent reliability, and offers nearly instant

nnectivity to virtually any person in the industrialized world.

one service is probably the single most utilized form of survival

mmunications, used whenever 911 is dialed, or a person phones a

iend for help.

ile basic phone has never been completely secure, it's become

ry apparent that phone services are approaching a nearly total

curity compromise, at least with respect to national agencies.te that with modern signaling and billing records systems,

ery phone call is logged, and the phone number, which is

fectively an address to a physical location for wired phones,

present with each call; this is true even of pay phones.

e exposure risk associated with basic phone systems is extreme.

y communications which is intended to remain private probably

ouldn't rely on phones. This is of no bearing for most

nventional survival scenarios.

one service can fail at any time, but due to very good survival

gineering, basic phone service often stays operational days after

power fails. Destruction of inside plant (central officeitching equipment, batteries, and power generation) or outside

ant (poles, wiring, and transmission equipment) will result in

ilure of service, of course. Note that in floods, hurricanes,

d earthquakes phone service often fails in a widespread way,

ereas failure in common storms and civil disorder is usually

calized.

te that while phone service may continue to be reliable during a

saster, communications may be difficult due to overloading. During

e summer of 1996, a power outage in the Western United States

sulted in a flood of calls to 911 systems in several states from




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ople simply reporting that their power was out; in some areas, 911

iled completely, or had hold times in excess of 30 minutes.

Private Point-to-Point (Intercoms and Field Phones)

tside of PBXs located in buildings, private wired communications

en't very common. Two notable exceptions are intercom systems that

e used to communicate within a building, and field phones, which

e essentially military versions of intercoms. Intercoms are

nerally limited in range.

-called wireless intercoms use the AC power line to convey their

gnal, and are generally dependent on AC power themselves. Wired

tercoms usually don t cover more than a few hundred feet in a

ilding, due to the wiring difficulties. Such intercoms usually

n on batteries. Field phones are generally used in environments

ere complete control of the lines of communication exist. The

pical military field phone runs on two D cell batteries, and

n operate over up to twenty miles of two-conductor wire.

general, private wired communications is the most secure, . The

res themselves can be followed if not concealed, revealing both

ints of communications.

Radio Signalsere are a huge number of possible options for radio-based survival

mmunications, ranging from getting broadcasts from authorities via

$4 AM radio to portable satellite phones.

Broadcast Radio

M Radio

t s be blunt. If you can have only one radio, if you have less

an ten bucks to buy equipment, forget CB, Ham, and everything

se. Get a portable AM radio. The first radio band for survival,

ws, and government information is the old AM radio band, from

0 Khz to 1700 Khz.

uipment can be very small, with typical radios 1x3x4 in size,ght, low-power (two AA batteries can run a radio for weeks at

w volume or with earphones), cheap (Radio Shack's FlavorRadio is

), very reliable (single IC), long range (100s of miles for

ear-channel radio stations at night)

addition to the radios themselves being reliable, AM broadcast

dio stations themselves are also fairly reliable with back-up

ansmitters, emergency generators, and bomb shelters: a few radio

ations in every area are part of a extremely reliable network that

a carryover from the civil-defense radio network's heydays of the

50's. The two civil defense frequencies are 640 Khz and 1240 Khz.

a result of the defense network carry-over, and the fact that

ny AM stations offer talk-radio call-in formats, AM radio iseal for getting news and information during emergencies, probably

re so than any other source.

e military and other government agencies also maintain emergency

rtable radio stations for disaster-stuck areas, that are AM

ations. Inexpensive AM radios with ferrite bar antennas have a

condary survival use as navigation instruments. Such radios have

arp, well-defined nulls where the signal goes dead. If one knows

e direction of the nulls of the radio and the locations of the AM

dio stations in the area, it's possible to triangulate your own

cation based on the directions your radio indicates each station




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in. Accuracy isn't incredible, but it can generally give a position

+/- 5 miles if the radio stations are 50 miles away.

thin the US, there was originally a set of stations set up with

at is known as clear channels that made sure a single, high power

ation had no others within hundreds of miles on the same frequency.

rrently these are known as Class A stations (which run 50,000 watts).

ese stations can be heard for hundreds of miles at night, allowing

steners in disaster-striken ares to hear stations that are in

rviving areas. (for example: At night, one can hear WMAQ, Chicago

the eastern edge of the Colorado Rockies without much difficulty.)

fer to Appendix A for a list of Class A Clear Channel stations.

Two-Way Radio

Unlicensed Services

l radio services are regulated in some form, even if it's a law

at states that the service is unregulated. However, there are

veral license-free services in the U.S. Note that other locations

en't quite as progressive in terms of unregulated services. The

K., for example, requires CB radios to be licensed, and doesn't

fer a free 1750 meter band. YMMV!

Radio (AM and SSB)

, also known as Citizen's Band (or Children's Band to its

tractors) uses an amplitude-modulated signal on forty channels

ntered around 27 Mhz. These radios are limited by FCC regulation

four watts of output power going up the antenna. Typically,

om a vehicle with an average antenna on flat terrain this results

a reliable range of ten to twenty miles.

th a better antenna, considerably longer ranges are possible.

wever, another FCC regulation requires CB operators to take steps

prevent their signal from being detectable beyond 150 miles. CB

equencies are plagued with a number of problems, such as

ercrowding on certain frequencies and considerable rudeness.

pically, Channel eleven is considered a general calling channel,

d Channel nineteen is used by truckers. In addition, Channel nine

reserved by law for emergency use only.

fer to Appendix B for a list of Citizens Band Channel Frequency

signments.

rt 15 Radio Bands

-called part 15 bands owe their name to the United State's Federal

mmunications Commission, which has a set of rules (Part 15) which

low certain types of unlicensed radio transmitters. There are

ree main part 15 bands that are commonly used for two-way voice

mmunications (other bands exist under part 15 for a plethora ofher devices.) The only band that's really significant is the 49

z band; the other two are interesting, but probably impractical.

Mhz Radios

e 49 Mhz band is a widely-used consumer radio band, primarily for

rdless phones. There are 10 narrow-band FM channels between 49.67

d 50.00 Mhz assigned to the band (Refer to Appendix C). The band

relatively noise-free in non-industrial areas, though the millions

cordless phones means plenty of interference in highly urban

ttings. Power output is specified by field strength, 10,000




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olts/meter at 3 meters, and translates to a few milliwatts. The

nd is most useful for short-range communications.

e receivers of good radios are such that this low power gives a

4 mile range, though field tests show ranges of 1/8 to 1/2 mile,

pending on terrain. The radios perform amazingly well in difficult,

lly terrain at short range. In very controlled tests using a

b-grade receiver/antenna, a detection range of three miles was

tained. Equipment is small and light, often only 1x3x7 or

aller; it's offered by many manufacturers that also make CB radio

uipment. Power requirements are miniscule, with RX requirements of

ss then 20 milliwatts and TX requirements of 100 milliwatts. (In

e test with a radio using three AA lithium batteries, run time in

mode was two WEEKS continuous.)

ough very reliable electrically, durability is a concern, as most

uipment is built with light plastic cases and no waterproofing.

st is generally $25-$40 per unit with features of single vs.

ltiple channel and voice-operated switching accounting for the

st difference. Note that kiddie walkie-talkies also operate on

is band but the receivers of such radios are worthless.

e to the proliferation of small, inexpensive 2-way radios for this

nd, there is no realistic hope of private communications-indeed,'s entirely possible that this band will become so crowded as to

useless in the event of an emergency.

addition, there are no standard frequency uses or nets on this

nd. Considering the limited range, the primary use will likely

for tactical communications among a small group, such as

ordinating camp activities. One group sends a scout ahead in

fficult terrain while the rest of the backpacking party waits,

th the scout calling back if the path taken is viable; this saves

urs of useless backtracking.

secondary use is to place a radio with volume set on maximum on a

ck that is cached in a well-camoflauged environment. The squelcheps the radio quiet, but another radio can transmit sounds

lowing the user to home-in on the hidden pack.

e 49 Mhz band is smack-dab in the middle of the VHF-low band

0-88 Mhz, 25 Khz channel spacing) that the military use world-wide

r primary tactical communications. It should be no surprise then

at there's quite a variety of ground-based, airborne, and

tellite-based radio equipment dedicated to intercepting,

rection-finding, and jamming these frequencies, which include

e 49 Mhz band.

eoretically, consumer 49 Mhz radios and military VHF-low radios

ould inter-operate. However, the reality is that only some militarydios operate with narrow band FM, and the tuning steps of the

dios are 25 Khz at best, frequently placing them off-channel.

wer tactical radios, such as the US Army SINCGARS (Single Channel

ound and Airborne Radio System, are usually operated in

equency-hopping mode, in which there is no hope of inter-operability

uch radios can however be tuned to single channels)

though highly susceptible to interception and direction-finding,

practice the range of consumer radios on this band is so limited

at this highly unlikely to occur unless a party is expressly

arching for the signal in the immediate area; the short range also




7/19

kes these one of the few radios immune to satellite-based DF. In

ban environments there are literally hundreds of competing signals

the same frequency, making interception and DF difficult. Note

at in scenarios involving military conflict, operational jammers

uld make these radios unusable at tens of miles away, and these

dios are likely to be unintended victims, jammed simply because

ey're in the middle of a military band, and not due to overt

tent.

e group known to us has primary communications based on 49 Mhz

dios. The limited range and extremely low power consumption were

ys, along with the fact that the group stays close together 100%

the time were factors that lead to the decision.

0 Mhz Family Radio Service (FRS)

e FRS radio service is a recent addition in the US and a good

lection of low cost equipment is available. The radios are

latively low power 500-600 milliwatts (0.5-0.6 watts), and

erate on 14 channels in the 460 Mhz frequency range using

liable FM modulation. The radios have a user settable

uelch level control to minimize interference. In addition,

e radios utilize a system known as Continuous Tone Coded

uelch System (CTCSS) which allows an additional degreeinterference control. These radios have a useable range

to 2 miles depending on terrain conditions. Refer to

pendix D for a list of FRS frequencies and Appendix E

r a discussion of CTCSS.

50 Meter Lowfer Band

the US, the 1750-meter band allows radios to operate with 1 Watt

power into a 50 foot long transmission line/antenna system at

equencies in the 170 Khz (that s 0.170 Mhz) range with no license.

is is a *really* low frequency.

uipment for 1750 meters is generally as small as one wants to

ild it. There are only a few commercially built radios for this

nd, generally the same size and weight as a larger mobile CB radio.

wer consumption is quite low, with about 3 watts peak for TX and

ndreds of milliwatts at most for RX. Cost is generally no more

an $200 for a top-end commercial built radio.

tennas are inefficient and large, since the 50 foot limit really

eds to be exploited for the radio to work well. Communication is

erefore not very reliable at long ranges; however, at short ranges

few miles) at night, when the noise level is low, 1750 meters is

liable. At night during the winter, it provides the greatest range,

th reasonably reliable contacts at 100's of miles. During themmer this band is plagued with static making it rather unreliable.

e 1750 Meter band is a (barely) plausible survival radio band only

it's used for a network among users that are located near each other.

ere are a few experimenters on this band that perform low-rate

ta communications using exotic modulation methods, but most prefer

rse code or SSB. There are no regularly monitored channels or

rvival networks in operation, though some radio enthusiasts in

lifornia do have a regular net.

is, however, worth noting, that some caving and spelunking




8/19

thusiasts also sometimes use this band, as low frequencies have

me limited ability to penetrate obstacles such as the ground. (The

me principle is used by the US Navy, which uses VLF and ELF

gnals to contact submarines)

ere's one survivalist of note that does use this band: the U.S.

vernment. A special high-survivability data network known as the

ound-wave emergency network, or GWEN, can be heard between 150

d 170 Khz with a repetitive noise that sounds like a cross between

hiss and a crunching sound. This network is intended to survive a

ssive nuclear strike and provide low-data-rate post apocalyptic

mmunications.

w frequencies are so easy to direction find that they are the

sis of the first radio-navigation system used for aircraft and

ips. Starting at about 200 Khz, there are thousands of low-power

n-directional beacons (NDBs). Automatic-direction-finding (ADF)

dios tuned to an NDB indicate their direction with high accuracy,

d many ADF receivers are capable of tuning the 1750 meter band.

the plus side, although direction-finders work really well here,

e low power and low frequency of the 1750 Meter band make it

fective for covert communications; few receivers tune this low,

d even fewer people even bother to listen. Due to the inefficienciesthe antenna system jamming is difficult, and there is no known

ployed jamming equipment capable of disrupting this band.

cro-power AM and FM

so permitted under part 15 is low-power (100 milliwatts) AM

ansmitters with a 10 foot antenna restriction on the same band as

oadcast AM radio.

e AM band shares many characteristics and difficulties of the

50-meter band. Equipment is generally always hand-made, usually

om AM broadcast kits. Receivers can be cheap AM receivers, but a

able communication system will likely use a sensitive medium wave

short wave radio receiver. Cost of the transmitter can be as low$20, the receiver $5 to $5000.

ansmitter size is generally the size of a small mobile CB, about

6x6. Power consumption is minimal, under 1/2 watt. Reliable

ception ranges of a 1/4 mile or so are common, though with good

ceivers and quiet band conditions (at night, during the

nter time) on an unoccupied AM channel (rare in its own right)

nges of 100's of miles have been obtained.

gnals are easy to direction find (indeed, many aircraft ADF

stems also tune the AM radio band) and it s trivial to jam

ak-signal reception in the AM band when Mother Nature isn't doing

herself with thunderstorms.

nets are known to use micro-power AM, though some pirate-radio

oadcasts violate the FCC's power specification and some of these

ansmit vaguely survival-related gloom-and-doom conspiracy radio

ogramming. This (with legal power, and probably better, community-

lated programming, of course) is probably the only viable use for

is band in a survival context (weak as though that may be.)

cro-power FM stations are also permitted, but the large bandwidth

d low power allowed makes micropower FM even more useless than AM.




9/19

) Licensed/Regulated Services

(a) Amateur ( Ham ) Radio

e bands listed below all require a license for use in the United

ates and most other countries with one important exception: Under

law (Part 97 of the FCC regulations), a station may lawfully use

y and all means at its disposal to locate help in the case of a

gitimate emergency.

Meter Band

e six-meter band (50-54 Mhz ham band) is considered sort of a

chizophrenic" band, that can't make up its mind whether to be a

rldwide/distant contact band or a local VHF band. It generally has

en known to be used as both of these. The use of this band is

imarily a local phenomenon-extremely popular in some areas and

mpletely silent in others.

Meter Band

Meters (144-148 Mhz.) is one of the most commonly used bands in

e United States. Frequently these days, when a ham buys his first

dio, it's a mobile or handheld 2-meter FM transceiver. SSB and

are rarely, but occasionally used on this band. However, 2M is

favorite for amateur radio satellite and amateur Earth-Moon-Earth

mmunications, and for technical reasons these methods require thee of SSB or CW rather than FM. This band, along with the

-centimeter (432-450 Mhz) band, are among the most popular bands

r local packet (data) radio communications, and are also

nds-down favorites for Radio Amateur Civil Emergency Service (RACES)

d Amateur Radio Emergency Service (ARES) communications. Licensure

r the use of the above three bands in the United States is granted

the basis of two multiple-choice written examinations covering

dio theory, amateur practice, and FCC regulations. The ARRL

ebsite address above) maintains a list of examination sessions,

d study guides for these exams are on the shelf in most libraries

d bookstores.

/HF Bam Bands:the United States, ham radio bands exist at 1.8 Mhz, 3.5 Mhz,

Mhz, 10.1 Mhz, 14 Mhz, 21 Mhz, 24 Mhz, and 28 Mhz. These bands

e all capable of long-distance communications, depending on

mospheric and sunspot conditions, and have all been used for

rldwide communication. The most common emissions modes are

(Morse Code) and Single Sideband, but certain data communications

e also used. Equipment for these bands is all over the range

terms of price and complexity-low-power CW-only single frequency

ansmitters can be built for $20, and high end all-band all-mode

ansceivers can be bought for several thousand dollars. Literature

use of these bands is common, with "Low-Profile Amateur Radio"

Jim Kearman being an excellent (if basic) primer for people who

nt an introduction into low-power HF operation without much ine way of an antenna. A license from Federal Communications

mmission is required to transmit on these bands (with limited

ceptions explained above), and the license is based upon

amination of the licensee's understanding of radio theory and

w, and ability to receive and understand signals in the Morse code.

(1)Commercial Carrier and Emergency Services

llular Phones

Cellular phone is essentially a low-power UHF transceiver. When a

ll is made, the phone signals a fixed station called a 'cell.' The




10/19

ll transfers the signals between the radio waves and the phone

change. (A gross oversimplification, but detail is not required

re). Cell phone conversations are not private, any more than any

her radio conversation. Technically, the law says that they may

t be monitored, but this law is unbelievably easy to violate.

anners able to pick up cell frequencies are not sold to civilians

y more, but they can be built.

ll phones also depend upon a working cell. A power outage for an

tended period could result in shutdown. Also, cells can be

erloaded. In the event of a disaster, a cell can handle a given

mber of calls. Calls that exceed the cell capacity will be

jected, rendering communications ineffective.

ging

ging is essentially a method of one-way radio communication. An

dividual makes a telephone call to a given phone number, and is

ompted to enter a message. This message is then sent out over VHF

UHF radio to a specific pager. Some paging service allows the

splay of phone numbers.

hers actually permit one to email a message to a pager. This

rvice has an advantage, in that it can discreetly summon one to

eck in or go somewhere as needed, but is dependent upon a networktransmitter towers and phone lines, and therefore might not be

lly functional in a disaster. In June of 1998 the complete

ilure of the Galaxy IV satellite caused a shutdown of 90% of

e pagers in the continental US. This single point failure shows

e fallacy of relying on a single comms system.

Radio Operation and Procedures

radio-based communication system depend on two main elements to

rk: operational radio hardware, and procedures that allow the

nder and receiver to communicate.

Radio Equipment, Antennas, and Propagation

e dB or decibel (1/100th of a Bel) is a comparativeasurement based on a log scale. That is, there's something

asured against a reference. The decibel allows a very wide

nge of signal power to be represented with small, manageable

mbers:

Power Change Decibels

2X 3 dB

100X 20 dB

1,000,000X 60 dB

0.5 X -3 dB

0.000001X -60 dB

ings that increase a signal are usually called gains and thingsat decrease a signal s strength are called losses, and both

e usually measured in dB, with gains being positive and losses

gative. Note that if we compare power to a fixed reference,

ch as a 1 Watt or one milliwatt, the dB can also be a measurement

actual power; a transmitter with a 20 dBW output, for example,

s 100 Watts of power.

ere two major factors that determine total radio performance,

own as station gain (what the equipment does) and path loss (what

e environment does to the signal between the stations.)




11/19

may seem confusing, but it's as simple as this: If station

in is greater than path loss, you can communicate, otherwise,

u can't. If you can't communicate, you need to fix one or more

rts of the radio system until you have enough station gain.

e more power, a more sensitive/selective receiver, better

higher antennas. Typical station characteristics follow:

ation Gain Factors Good Base SSB CB

ansmit power +10 dBW (12 Watts)

ansmitting antenna height gain +3 dB

ansmitting antenna gain 0 dB

ceiving antenna height gain +3 dB

ceiving antenna gain 0 dB

ceiver sensitivity +149 dB (-149 dBW)

tal Station gain 165 dB

e ultimate goal of the radio system is to get a signal to

e receiver that's stronger than the background noise, so

e signal can be heard. This is known as signal-to-noise ratio,

d receiver sensitivity is usually stated as the lowest power

vel that will result in a given signal-to-noise ratio, typically

dB. Note that the receiver sensitivity is actually how much

signal can be reduced before it can t be heard (-149 dB) but

counts as a positive, as we have 149 dB in our station gaincount that we can lose before we can't hear a signal anymore.

e path loss is how of the signal is reduced by the environment.

stance, air, mountains, water vapor are some of these factors.

stance alone reduces the signal at a rate of the square of the

stance, e.g., a signal two miles away is one-quarter the strength

a signal one mile away, just because of the distance. Path

ss varies (just a little bit) with the frequency used until

e gets to microwaves, where path loss jumps significantly.

der ordinary conditions between two stations on average terrain,

th loss goes this way:

equency 10 Miles 25 Miles 50 Miles

Mhz (CB) -135 dB -152 dB -174 dB

4 Mhz (2M ) -134 dB -157 dB -175 dB

r a good SSB CB radio, we have 165 dB of station gain, and we can

mmunicate as long as path losses are less than this; on average

rrain, this is somewhere between 25 and 50 miles. Note that if the

tennas used are poor and low to the ground, this will change

ings considerably, as we'll see in a few paragraphs.

situations where the signal is bouncing around, such as short wave

dio signals, loss includes both distance and the efficiency that

e signal is reflected; when conditions are good, this reflectionficiency can be 100%, and only the distance matters. Likewise,

a satellite is used, the path loss is pretty much a result of

st the distances between the ground stations and the satellite

volved. Distance-only path losses run about -110 dB for 100

les, or a typical low-earth orbit, and -151 dB for 22,500

les, or geo-syncronous orbits. No place on earth is more than

,500 from any other location, so the path loss for a perfectly

flected short wave signal is somewhere in-between.

t that it's done, but our 165 dB of station gain is quite a bit

re than the 151 dB path loss of a geo-synchronous satellite, so it's




12/19

ivial for the satellite to hear a SSB CB or a 2-Meter Amateur

dio. Indeed, several emergency systems depend on this: simple 1/2

tt emergency-radio beacons are detected with low-earth orbit

tellites, and the newer 5-watt beacons are detected by

osyncronous weather satellites.

the late 1980's and early 1990's the space shuttle carried the

REX (Satellite Amateur Radio Experiment) program. Astronaut

ms utilizing the 2 meter (144-148 Mhz) band communicated to

ousands of earth bound hams, many utilizing only low power

.5-5 watt) hand held radios.

)Basic Radio Antennas

tenna Effectiveness

tennas can be measured by listening to a standard transmitter on

e frequency of interest, and changing the antenna and noting the

anges in the signal. Higher-end radios have meters that show

lative signal strength, using numbers of 1 to 9 (S1...S5...S9)

d then dB over S9; each S-unit is typically 6 dB. Using a calibrated

ceiver, we did measurements of a local weather station (near the

ateur 2-meter band) to illustrate several antennas. We used the

st antenna (which isn't very good at all, actually) as a reference,

d then compared several portable antennas:

tenna Sig. Strength dB % Signal

scone at 20 feet S9 0 dB 100%

2 Wave Rod 6 S5 -24 dB 40%

bber duck, 6 S3 -36 dB 2.5%

ing the same thing at CB frequencies:

tenna Sig. Strength dB % Signal

pole at 20 feet S9 0 dB 100%

bber duck, 6 S0 -54 dB .0004%

or antennas will reduce station gain; indeed is we use the SSB CB

ample where we had 165 dB of station gain, and change the antennas

ed to rubber duck antennas, the station gain plunges to justdB, not even enough to cover five miles! What these measurements

ow is that antennas can compromise perfectly good equipment, and

at it takes a good antenna for a radio to work well.

ere are several types of antennas that are easily built with

re or stiff metal rods that are suitable for survival use and

e also good antennas. As a general rule, if you want maximum

nge and station gain, use a good antenna and place it as high

possible, including climbing up mountains or hills.

) 1/4 WaveLength Vertical

is is perhaps the simplest antenna. Basically, it's a vertical rod

stiff wire fed by a feed line at the bottom and cut to about onearter of the desired wavelength. It radiates uniformly in all

rections, and is the most common type for handheld and

hicle-mounted radios.

)Dipole

other simple antenna. Basically, it consists of two wire "legs"

1/4 wavelength each pointed in opposite directions, and either

rizontal or sloped. This antenna is most commonly used for Medium

d High-Frequency ham radio and short wave listening (1.8-30 Mhz).

radiates most strongly in a direction perpendicular to the long

is of the wires. The overall length in feet is calculated by the simple




13/19

uation: 468/Freq (in Mhz). For example a dipole cut to operate

3950 Khz (3.95 Mhz) would be 468/3.95 or 118.5 feet total length

59.25 (60 feet) on each leg. This length if generally only

itical for transmitting.

ads and Yagis

ads and Yagis are two types of directional antennas. A Yagi has a

nter element, called a driven element, which is connected to the

ed line from the transmitter. This element is cut to roughly one-

arter of the desired wavelength, and mounted on a horizontal boom.

en, slightly shorter elements, called "director elements" are cut

d mounted on the boom on one side of the driven element. Slightly

nger elements, called "reflector elements" are cut and mounted on

e other side, and the whole antenna is generally mounted on a

tatable mount. The director and reflector elements are typically

ch 5% shorter of longer than the previous one of the same type.

ese types of antennae tend to be highly directional, favoring

e direction towards the director elements, and are frequently

ed for HF, VHF, and UHF ham radio stations.

(1)Signal Operating Instructions and Radio Nets

gnal Operating Instructions (SOI) is the military name given to a

ole host of methods and procedures to communicate; essentially,

I is a protocol of behavior for people and equipment tommunicate successfully.

e single most important thing to remember is that that it takes

meone listening for communications to work, and the best radios

the world are useless if no one hears you call for help.

tablishing or connecting to a radio net of listeners, making

re that someone is out there listening for you, is the single

st important step to take in radio communications. Period.

hedules

's impractical for most people to listen to radios continuously,

having a schedule for stations on your net to listen makes radio

mmunication practical. Either use a published schedule, or agular interval (every day at 7pm, for example) for the net to

me on-line.

ard Channels

l radio users need to be on the same frequency to communicate.

special listening frequency makes monitoring easy; for example,

CB radios, channel 9 is used only for emergency traffic, so

u can listen to this channel and know if you hear something,

is (at least in theory) important. In many areas, there are

ateur radio repeaters with a feature known as LTZ (Long-tone-zero)

ich is used to turn on receivers of regular listeners, for when

lp is needed. Your radio net should have a guard channel to

sten to when the net isn't active, and a one or more netannels for when it is. (Depending on other factors, these

annels may be changed regularly or not.)

des

general, the use of codes, ciphers, and other encryption on most

dios is illegal in the United States if the intent of the code is

obscure the meaning of a message. There are legal uses for codes

CB and ham radios-see below under "Brevity and Message Coding"

thentication

thentication is the art of verifying that all people in a given




14/19

t are people who have legitimate access, for example through the

e of unannounced questions. For example, during World War Two,

was a popular perception that no German soldier would know anything

out baseball. As a result, American GI's would frequently quiz

ch other about baseball trivia to be sure that everyone present

s in fact an American. (There have been horror stories about

erican generals who knew nothing about Shoeless Joe Jackson

d spent more time under guard than they would have liked, which

es to prove that an authentication system should not be so

phazardly managed on a large scale)

evity and Message Coding

dio communication takes time and bandwidth. Certain codes have

come agreed-upon conventions to compress a relatively large amount

information into a relatively small amount of space. For example,

most everyone who listens to a CB or to police radio has heard the

en codes" in which a sender may say "Ten-four" and be understood

everyone listening as having said "Your message is acknowledged"

fer to Appendix H: Amateur Radio Q-Signals for an additional

andard list of specialized abbreviations.

I Spares

ving extra copies of your Signal Operating Instructions can be a

uble-edged sword. On one hand, if your SOI is at all complex oraborate, losing your only copy could be crippling. However, if

ur net's integrity depends upon not having your procedures widely

own, an extra SOI is a copy of the SOI waiting to fall into the

ong hands. Alternately, multiple copies of SOI's with attached

thentication codes may also be utilized.

Visual Signals

rse code by light

ips carry a set of blinker lights for communication by morse code.

ese lights are essentially searchlights fitted with shrouds or

utters that can be quickly opened or closed.

maphore

the days before wired telegraphy, a code was used to send

ssages over long distances called semaphore. Basically, the sender

ood atop a hill holding a brightly colored flag in each hand. He

uld face the receiving station and raise his arms up out to his

des, and the angle at which he held his arms would signify a given

meral or letter.

ree-in-a-row rule (whistles, gunshots...)

general, three of any signal repeated at a regular interval

gnifies distress. For example, a hunter who is lost can fire three

ots in the air a few seconds apart. Theoretically, anybody in the

cinity will hear the three shots and realize that the hunter is inme sort of distress, and will be able to figure out the direction

search from the sound of the shots. As a practical matter, it's

likely that such a signal will be taken seriously unless the sender

its until after dark. After dark during hunting season at least the

cal game officer will be hunting you.

erican sign language

gn language consists of an alphabet and a set of symbols each

presented by a set of hand signals. This information is quiet,

vert, and generally unknown within the non-hearing impaired




15/19

mmunity. Like Morse and Semaphore is could provide a clandestine

d useful communications alternative with practice.

OSSARY

: Amplitude Modulation

CSS Continuous Tone Coded Squelch System (CTCSS)

Refer to Appendix E

: Continuous Wave

MF: Dual Tone Multi-Frequency Refer to Appendix G

: Frequency Modulation

Z: Long Tone Zero - Transmission of a DTMF '0'

for a long relative time (usually > 2-3 seconds)

used for specific control of repeaters and related

equipment.

B: Lower Side Band

dulation: The mechanism for impressing information (voice or data)

onto a carrier frequency.

T: Network

B: Single Side Band

B: Upper Side Band

b-Audible: Refer to CTCSS

pendix A: AM Class A Clear Channel Stations

EQ CALL CITY STATE

0 KYUK BETHEL AK

0 KYAK ANCHORAGE AK

0 KFAR FAIRBANKS AK

0 KDLG DILLINGHAM AK

0 KBRW BARROW AK

0 KBYR ANCHORAGE AK

0 KOTZ KOTZEBUE AK

0 KFQD ANCHORAGE AK

0 KCHU VALDEZ AK0 KNOM NOME AK

0 KCBF FAIRBANKS AK

0 KABN LONG ISLAND AK

0 KICY NOME AK

0 KBBI HOMER AK

20 KFFR EAGLE RIVER AK

80 KASH ANCHORAGE AK

70 KJNP NORTH POLE AK

90 KAAY LITTLE ROCK AR

0 CMJP CIEGO DE AVILA, CAM. CA

0 KFI LOS ANGELES CA

0 KNBR SAN FRANCISCO CA

0 KGO SAN FRANCISCO CA0 CMJV CIEGO DE AVILA CA

70 KNX LOS ANGELES CA

0 KOA DENVER CO

80 WTIC HARTFORD CT

0 WSB ATLANTA GA

40 WHO DES MOINES IA

0 WMAQ CHICAGO IL

0 WGN CHICAGO IL

0 WBBM CHICAGO IL

0 WLS CHICAGO IL

00 WMVP CHICAGO IL




16/19

90 WOWO FORT WAYNE IN

0 WHAS LOUISVILLE KY

0 WWL NEW ORLEANS LA

30 KWKH SHREVEPORT LA

30 WBZ BOSTON MA

90 WBAL BALTIMORE MD

0 WJR DETROIT MI

0 WCCO MINNEAPOLIS MN

20 KMOX ST. LOUIS MO

10 WBT CHARLOTTE NC

10 KFAB OMAHA NE

0 WFAN NEW YORK NY

0 WOR NEW YORK NY

0 WABC NEW YORK NY

0 WGY SCHENECTADY NY

0 WCBS NEW YORK NY

30 WBBR NEW YORK NY

80 WHAM ROCHESTER NY

0 WLW CINCINNATI OH

00 WTAM CLEVELAND OH

70 KVOO TULSA OK

90 KEX PORTLAND OR

20 KDKA PITTSBURGH PA

60 KYW PHILADELPHIA PA10 WPHT PHILADELPHIA PA

0 CMAA PINAR DEL RIO PR

0 CMAC PINAR DEL RIO PR

0 CMAB PINAR DEL RIO PR

0 WSM NASHVILLE TN

0 WBAP FORT WORTH TX

80 KRLD DALLAS TX

00 WOAI SAN ANTONIO TX

60 KSL SALT LAKE CITY UT

40 WRVA RICHMOND VA

0 KIRO SEATTLE WA

00 KOMO SEATTLE WA

70 WWVA WHEELING WV

s a personal note from the editor, WBBM-780 Chicago deserves

ecial credit for being a solid general news outlet in normal

mes)

pendix B: Citizens Band Channel Frequencies

annel Freq Channel Freq Channel Freq Channel Freq

mber Mhz Number Mhz Number Mhz Number Mhz

1 26.965 11 27.000 21 27.215 31 27.315

2 26.975 12 27.105 22 27.225 32 27.325

3 26.985 13 27.115 23 27.255 33 27.3354 27.005 14 27.125 24 27.235 34 27.345

5 27.015 15 27.135 25 27.245 35 27.355

6 27.025 16 27.155 26 27.265 36 27.365

7 27.035 17 27.165 27 27.275 37 27.375

8 27.055 18 27.175 28 27.285 38 27.385

9 27.065 19 27.185 29 27.295 39 27.395

10 27.075 20 27.205 30 27.215 40 27.405

pendix C: 49 Mhz Channel Frequencies

Base Handset




17/19

46.61 49.67 Cordless phone Ch 1










pendix D: 460 Mhz Family Radio Service (FRS) Channel Frequencies

: 462.5625 08: 467.5625 Modulation is FM

: 462.5875 09: 467.5875

: 462.6125 10: 467.6125

: 462.6375 11: 467.6375

: 462.6625 12: 467.6625

: 462.6875 13: 467.6875

: 462.7125 14: 467.7125

CSS (Coded Tone Carrier Squelch System)

e CTCSS System prevents unwanted noise and/or conversation

om being heard through your FRS radio's speaker. Only signalsth the correct code will be heard. To use the system each

dio must:

A) be on the same channel

B) have the same CTCSS Code selected.

en enabled, the Privacy Code is transmitted with each voice

ssage. All receivers programmed with the same code will open

eir speaker circuits and the message will be heard.

is VERY important to note that conversations on your FRS

dio are NOT private. Any other FRS radio or scanner can eaves

op on your conversation. Also, it is always best to monitor,

th the monitor button, prior to transmitting to prevent disruptingy nearby conversations that you may not hear on the channel.

pendix E: Continuous Tone Coded Squelch System (CTCSS)

Sub-audble audio frequencies in Hertz

: 67.0 09: 91.5 17: 118.8 25: 156.7 33: 210.7

: 71.9 10: 94.8 18: 123.0 26: 162.2 34: 218.1

: 74.4 11: 97.4 19: 127.3 27: 167.9 35: 225.7

: 77.0 12: 100.0 20: 131.8 28: 173.8 36: 233.6

: 79.7 13: 103.5 21: 136.5 29: 179.9 37: 241.8

: 82.5 14: 107.2 22: 141.3 30: 186.2 38: 250.3

: 85.4 15: 110.9 23: 146.2 31: 192.8: 88.5 16: 114.8 24: 151.4 32: 203.5

pendix F: Emergency Frequencies

HF Marine emergency frequencys.

2182, 4125, 6215, 8291, 12290, 16420 voice communications (SSB)

Aviation 121.5 Mhz Voice or beacon

Military 223.0 Mhz Voice or beacon

EPIRB 121.5, 223.0, 406mhz

406 beacon is digital only with beacon on 121.5 and 223.0




18/19

CB channel 9, 27.065

VHF marine freq Channel 16, 156.800mhz

GMRS 462.675 unoffical emergency/traffic/travel aid request freq.

FCC estimates that %30 of the US is monitored by an official

group REACT on this freq.

Non-emergency but usefull frequencies:

NOAA weather 162.40, 162.475, 162.55, 162.525, 162.5

Ham calling freq

6 meters 52.525

2 meters 146.52

1 3/4 meter 223.5

70cm 446.0

1296 1294.5

pendix G: Dual Tone Multi-Frequency (DTMF) Audio Frequencies

These are the tones transmitted when you press a key on your

telephone touch pad. The tone of the button is the sum of the

column and row tones. The ABCD keys do not exist on standardtelephones.

1209 1336 1477 1633

697 1 2 3 A

770 4 5 6 B

852 7 8 9 C

941 * 0 # D

pendix H: IARU Phonetic Alphabet

In a noisy environment, phonetic spelling of certain words

made be required for understanding. This is the standard

phonetic alphabet utilized by military and aviation as

specified by the International Administrative Radio Union,

which is a international governing body on communications

standards.

Example:

IARU - Say: "IARU I Spell, India, Alpha, Romeo, Uniform"

A: Alpha N: November

B: Bravo O: OscarC: Charlie P: Papa

D: Delta Q: Quebec

E: Echo R: Romeo

F: Foxtrot S: Sierra

G: Golf T: Tango

H: Hotel U: Uniform

I: India V: Victor

J: Juliet W: Wiskey

K: Kilo X: X-Ray

L: Lima Y: Yankee

M: Mike Z: Zulu




19/19

pendix I: Amateur Radio Q-Signals

ese signals are a form of legal code, used to shorten Morse Code

ssages

compressing a complete idea into three letters. Following the Q signal

th an question mark makes it interrogative

G: Will you tell me my exact frequency?/Your exact frequency is _____

L: Are you busy?/I am busy. Please do not interfere.

M: Is my transmission being interfered with?/Your transmission is being

terfered with ___ (1= nil; 2=slighly; 3= moderately; 4= severely; 5=

tremely)

N: Are you troubled by static?/I am troubled by static ___(1-5 as under

M)

O: Shall I increase power?Please increase power.

P: Shall I decrease power?/Please decrease power.

Q: Shall I send faster?/Please send faster.

S: Shall I send slower?/Please send slower.

T: Shall I stop sending?/Please stop sending.

U: Have you anything for me?/I have nothing for you.

V: Are you ready?/I am ready.

X: When will you call me again?/I will call you again at ____ hours.

Z: Who is calling me?/You are being called by ____B: Are my signals fading?/Your signals are fading.

K: Can you hear me betwen your signals and if so can I break in on your

ansmission?/I can hear you between my signals; break in on my

ansmission.

L: Can you acknowledge receipt of a signal?/ I acknowledge receipt.

N: Did you hear me on (____) kHz?/I heard you on (____) kHz.

O: Can you communicate with ____directly or through relay?/I can

mmicate with ____directly or through relay.

P: WIll you relay to ____?/I will relay to ____.

T: General call preceding a message to all stations.

X: Will you listen to ____ on ____ kHz?/I will listen to ____ on ____

z.

Y: Shall I change to transmission on another frequency?/Change toansmission on ____ kHz.

B: Do you agree with my counting of words?/I do not agree with your

unting of words. I will repeat the first letter of each word or group.

C: How many messages have you to send?/I have ____ messages for you.

H:What is your location?/My location is____

R: What is the correct time?/The correct time is ____ (Timezone stamp)


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