========
Survival Communitcations FAQ Version 0.5

  DISCLAIMER: The authors and editors of this FAQ panel assume no
legal responsibility for           any errors in or misuse of this
information, and are not to be held legally liable or responsible
for any death, injury, loss of property, or other negative
consequences resulting from use, misuse, or abuse of this information.
 
 This document was written mainly by a long-time lurker on
misc.survivalism. He sent it to me, and I filled in a few blanks,
deleted a few things that seemed confusing or spurious, and tried to
clean up the formatting somewhat.

Any comments should be sent to me at medintz@ukans.edu, and will be
acted on or forwarded to the author as appropriate.

This document is being archived at
http://falcon.cc.ukans.edu/~medintz/comfaq.txt

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of the document http://falcon.cc.ukans.edu/~medintz/disclaim.txt. In
general, redistribution, use, or storage is approved, but there are
certain stipulations and exceptions in that document that must be
obeyed.

This document is a work in progress. Suggestions, comments, and
recommendations are always welcomed, and will be acted on or forwarded
as appropriate.

Further information on radio may be gathered from _The ARRL Handbook_
and the _ARRL Operating Manual_, published by the American Radio Relay
League (http://www.arrl.org)

        A topic as broad as communications can never been completely
covered, especially in what should be a terse and matter-of-fact FAQ.
We ll start out  with the most general description we can provide, and
get more specific deeper in the document.
        WHAT COMMUNICATION IS
        The first step in understanding survial communications is
understanding of the fundamentals of communication itself.
Communication is a very complex topic, as difficult to completely
define as truth, beauty, or time, but we ll cut to the chase to make
our life simple with two definitions: 

COMMUNICATION is the successful transfer of information from one
person  to another person or entity.

COMMUNICATION SYSTEMS are comprised of equipment, methods and
techniques of supporting information transfer, enabling communication
to take place between two people.  (Please note that these definitions
are cheap outs, since we haven't defined what we mean by information,
but you get it, right? Note that we re also limiting things by
requiring at least one person in to loop, to reduce the scope of this
document.)

What Happens When We Communicate?
In order for any communication to take place, there s two major
requirements that must satisfied. 

REQUIREMENT ONE: There must be a sender and a receiver. For most
survival purposes, this means a person trying to send a message and a
person looking for a message sent to them.

REQUIREMENT TWO: The sender and reciever must understand how the
message is to be conveyed, and must understand the message itself.
Again, for survival purposes, this means that both people trying to
communicate understand how their communication system works (how to
operate the radio, that one or two lamps have different meanings, how
to look up a word in a dictionary) and that they understand the
message (the message in clear and in a common language, that one lamp
means  by land  and two lamps means  by sea. ) 

REQUIREMENT THREE: the communication system must be capable of
delivering the message. (There s not so much fog the lamps can t be
seen, the radios are within range and working properly. 

THE ONE RULE OF COMMUNICATIONS: To communicate, the sender
creates a message that both he and the reciever should understand.
Then, using a common system that is capable of delivering the message,
the sender transmits the message to the receiver, who understands the
message sent.
         
SURVIVAL IMPLICATIONS
Failure to communicate is always the result of a failure to meet the
requirements. A few specific examples:

The first requirement--that there s someone trying to send a message,
and someone listening--seems obvious, but in practice it s probably
the most  violated requirement of communications in a survival sense,
giving the violator a false sense of security until they need to
communicate.  For some reason, somebody buys a CB and thinks they can
be in the middle of nowhere, call for help on channel 9, and Air
Rescue magically appears to come in and save them. Yup, it s a long
day in hell when this happens. It s not just CB owners, either: this
requirement gets violated by amateur radio operators (I ll just call
for help on the repeater...except they left the directory home and
their rig doesn t provide the right subaudible tones, or the guy that
just answered your CQ or SOS on 40 meters thinks you re a crank). 

Nor is this limited to radio: flare guns (It s 2AM, a bear just ate
your camp partner, and you re fifty miles from civilization in a
valley. Shoot a flare off, and you ve made your camp brighter for a
few seconds and pissed off the bear. Feel better?) Air horns (same
scenario, maybe the bear leaves if it s loud enough.)

Resolving problems surrounding the first requirement simply means
making sure there s a person listening--perhaps someone you know,
perhaps not. The 911 system, for example, consists of people
continually monitoring a phone for incoming messages from senders.
World-wide, satellites and many pilots listen to 121.5 MHz on their
radios, looking for distress signals. If the CB er knew someone in the
area who agreed to listen on channel 9 for 15 minutes at 6PM everyday,
his chances of being heard then are vastly improved. The ham, who had
punched in the frequency to his club s repeater,  which has a
long-tone-zero emergency alert system that gets friends from the
club on would be in better shape too; and if the ham s friend was
listening at 6PM everyday on 40 meters, it s doubtful his friend would
think he was nuts if he said he needed help urgently. Having a friend
look for a flare on a ridge line a hour before sunrise--and climbing
to the ridge line to fire the flare--would  work wonders, too. Note
that in each of these cases, not only was someone listening, but there
was coordination, also, in that the recipient of the messages knew
when and where to look or listen.

What we ve learned:

1) Someone has to Send and someone needs to Listen.
2) Both have to use the same system. Both need to understand the

     message.
3) Coordination between the sender and listener vastly increases the

     liklihood of successful communications.
        
          A. Types of communications

1.Wired Communications
a)Basic Telephone Service 
Current telephone communications, at least in industrialized nations,
is the standard of excellence that most comunications systems are
compared. Disparaging comments and annoying customer service issues
asside, standard phone service is nearly universal, approaches 100
percent reliability, and offers nearly instant connectivity to
virtually any person in the industrialized world. Phone service is
probably the single most utilized form of survival communications,
used whenever 911 is dialed, or a person  phones a friend for help.

While basic phone has never been completely secure, it s become very
apparent that phone services is on the virge of nearly total security
compromise, at least with respect to national agencies. Note that with
modern signaling and billing-records systems, every phone call is
logged, and the phone number--which is effectly an address to a
physical location for wired phones--is present with each call; this is
true even of pay phones.
The exposure risk associated with basic phone systems is extreme. Any
communications which is intended to remain private probably shouldn t
rely on phones. This is of no bearing for most conventional survival
scenarios.
Phone service can fail at any time, but due to very good survival
engineering, basic phone service often stays operational days after AC
power fails. Destruction of plant or equipment--the central office,
patch boxes, wiring or the phone poles--will result in failure of
service, of course. Note that in floods, hurricanes, and earthquakes
phone service often fails in a widespread way, whereas failure in
common storms and civil disorder is ususally locaized.

Note that while phone service may continue to be reliable during a
disaster, communications may be difficult due to overloading. During
the summer of 1996, a power outage in the western united states
resulted in a flood of calls to 911 systems in several states from
people simply reporting that their power was out; in some areas, 911
failed completely, or had  hold times in excess of 30 minutes.

a) Private Point-to-Point (Intercoms and  Field Phones )
Outside of PBXs located in buildings, private wired communications
aren t  very common. Two notable exceptions are intercom systems that
are used to communicate within a building, and field phones, which are
essentially military versions of intercoms.  Intercoms are generally
limited in range. So-called  wireless  intercoms use the AC power line
to convey their signal--and are dependent on AC power   themselves.
Wired intercoms usually don t cover more than a few hundred  feet in a
building, due to the wiring dificulties. Such intercoms usually run on
batteries.
Field phones are generally used in environments where complete control
of the lines of communication exist. The typical military field phone
runs on two  D  cell batteries, and can operate over up to twenty
miles of two-conductor wire.
In general, private wired communications is the most secure, . The
wires themselves can be followed if not concealed, revealing both
points of communications.

1.Radio Signals
There s a huge number of possible options for radio-based survival
communications, ranging from getting broadcasts from authorities via a
$4 AM radio to portable satellite phones.

a)Broadcast Radio
 AM Radio
Let s be blunt. If you can have only one radio, if you have less than
ten bucks to buy equipment, forget CB, Ham, and everything else. Get a
portable AM radio. The  first  radio band for survival, news, and
government information is  the old AM radio band, from 550KHz to
1700KHz. Equipment can be very  small, with typical radios 1  x 3  x 4
in size, light, low-power (two AA batteries can run a radio for weeks
at low volume or with earphones), cheap (Radio Shack s  FlavorRadio
is $7), very reliable (single IC), long range (100s of miles for
clear-channel radio stations at night)      
In addition to the radios themselves being reliable, AM broadcast
radio stations themselves are also fairly reliable with back-up
transmitters, emergency generators, and bomb shelters: a few radio
stations in every area are part of a extremely reliable network that
is a carryover from the civil-defense radio network s heydays of the
1950 s. The two civil defense frequencies are ____ and ____. (insert
your area freq's here)
As a result of the defense network carry-over, and the fact that many
AM  stations offer talk-radio call-in formats, AM radio is ideal for
getting news and information during emergencies, probably more so than
any other source.
The military and other government agencies also maintain emergency
portable radio stations for disaster-stuck areas, that are AM
stations.
Inexpensive AM radios with ferrite  bar  antennas have a secondary
survival use as navigation instruments. Such radios have sharp, well-
defined  nulls  where the signal goes dead. If one knows the direction
of the nulls of the radio and the locations of the AM radio stations
in the area, it s possible to  triangulate  your own location based on
the directions  your radio indicates each station is in. Accuracy
isn't incredible, but it can generally give a position of +/- 5 miles
if the radio stations are 50 miles away.
Within the US, there was originally a set of stations set up with what
is known as  clear channels  that made sure a single, high power
station had no others within hundreds of miles on the same frequency.
Nowdays, these are known as  Class A  stations. These stations can be
heard for hundreds of miles at night, allowing listeners in
disaster-striken ares to hear stations that are in surviving areas.
(for example: At night, one can hear WMAQ-Chicago on the eastern edge
of the Colorado Rockies without too much difficulty.)
        FREQ   CALL CITY STATE
        640    KYUK BETHEL    AK
        650    KYAK ANCHORAGE AK
        660    KFAR FAIRBANKS AK
        670    KDLG DILLINGHAM     AK
        680    KBRW BARROW    AK
        700    KBYR ANCHORAGE AK
        720    KOTZ KOTZEBUE  AK
        750    KFQD ANCHORAGE AK
        770    KCHU VALDEZ    AK
        780    KNOM NOME AK
        820    KCBF FAIRBANKS AK
        840    KABN LONG ISLAND    AK
        850    KICY NOME AK
        890    KBBI HOMER     AK
        1020   KFFR EAGLE RIVER    AK
        1080   KASH ANCHORAGE AK
        1170   KJNP NORTH POLE     AK
        1090   KAAY LITTLE ROCK    AR
        580    CMJP CIEGO DE AVILA, CAM.     CA
        640    KFI  LOS ANGELES    CA
        680    KNBR SAN FRANCISCO  CA
        810    KGO  SAN FRANCISCO  CA
        900    CMJV CIEGO DE AVILA CA
        1070   KNX  LOS ANGELES    CA
        850    KOA  DENVER    CO
        1080   WTIC HARTFORD  CT
        750    WSB  ATLANTA   GA
        1040   WHO  DES MOINES     IA
        670    WMAQ CHICAGO   IL
        720    WGN  CHICAGO   IL
        780    WBBM CHICAGO   IL
        890    WLS  CHICAGO   IL
        1000   WMVP CHICAGO   IL
        1190   WOWO FORT WAYNE     IN
        840    WHAS LOUISVILLE     KY
        870    WWL  NEW ORLEANS    LA
        1130   KWKH SHREVEPORT     LA
        1030   WBZ  BOSTON    MA
        1090   WBAL BALTIMORE MD
        760    WJR  DETROIT   MI
        830    WCCO MINNEAPOLIS    MN
        1120   KMOX ST. LOUIS MO
        1110   WBT  CHARLOTTE NC
        1110   KFAB OMAHA     NE
        660    WFAN NEW YORK  NY
        710    WOR  NEW YORK  NY
        770    WABC NEW YORK  NY
        810    WGY  SCHENECTADY    NY
        880    WCBS NEW YORK  NY
        1130   WBBR NEW YORK  NY
        1180   WHAM ROCHESTER NY
        700    WLW  CINCINNATI     OH
        1100   WTAM CLEVELAND OH
        1170   KVOO TULSA     OK
        1190   KEX  PORTLAND  OR
        1020   KDKA PITTSBURGH     PA
        1060   KYW  PHILADELPHIA   PA
        1210   WPHT PHILADELPHIA   PA
        550    CMAA PINAR DEL RIO  PR
        740    CMAC PINAR DEL RIO  PR
        740    CMAB PINAR DEL RIO  PR
        650    WSM  NASHVILLE TN
        820    WBAP FORT WORTH     TX
        1080   KRLD DALLAS    TX
        1200   WOAI SAN ANTONIO    TX
        1160   KSL  SALT LAKE CITY UT
        1140   WRVA RICHMOND  VA
        710    KIRO SEATTLE   WA
        1000   KOMO SEATTLE   WA
        1170   WWVA WHEELING  WV

a)Two-Way Radio
1)Unlicensed Services
All radio services are regulated in some form, even if it s a law that
states that the service is unregulated. However, there are several
license-free services in the U.S. Note that other locations aren t
quite as progressive in terms of unregulated services. The U.K., for
example, requires CB radios to be licensed, and doesn t offer a  free
1750 meter band. YMMV!

CB Radio (AM and SSB)
CB, also known as Citizen's Band (or Children's Band to its
detractors) uses an   amplitude-modulated signal on forty channels
centered around 27 MHz. These radios are limited by FCC regulation to
four watts of output power going up the antenna. Typically, from a
vehicle with an average antenna on flat terrain this results in   a
range of ten to twenty miles. With a better antenna, considerably
longer ranges are possible. However, another FCC regulation requires
CB operators to take steps to prevent their signal from being
detectable beyond 150 miles. CB frequencies are plagued with a number
of problems, such as overcrowding on certain frequencies
and considerable rudeness. Typically, Channel eleven is considered a
general calling channel, and Channel nineteen is used by truckers. In
addition, Channel nine is reserved by law for emergency use only.
 
Part 15 Radio Bands
So-called  part 15  bands owe their name to the United State s Federal
Communications Commission, which has a rule (Part 15) which allows
certain types of unlicensed radio transmitters. There are three main
part 15 bands that are commonly used for two-way voice communications
(other bands exist under part 15 for a plethora of other devices.) The
only band that s really significant is the 49 MHz band; the other two
are interesting, but probably impractical.
        49 MHz Radios
The 49 MHz band is a widely-used consumer radio band, primarily for
cordless phones. There are 10 narrow-band FM channels between 49.67
and 50.00 MHz assigned to the band. The band is relatively noise-free
in non-industrial areas, though the millions of cordless phones means
plenty of interference in highly urban settings. Power output is
specified by field strength -- 10,000 uVolts/meter at 3 meters, and
translates to a few milliwats. The band is most useful for short-range
communications.
The recievers of good radios are such that this low power gives a 1/4
mile range, though field tests show ranges of 1/8 to 1/2 mile,
depending on  terrain. The radios perform amazingly well in difficult,
hilly terrain at short range. In very controlled tests using a
lab-grade reciever/antenna, a detection range of three miles was
obtained.  Equipment is small and light, often only 1  x 3  x 7  or
smaller; it's offered by many manufacturers that also make CB radio
equipment. Power requirements are miniscule, with RX requirements of
less then 20 milliwatts and TX requirements of 100 milliwats. (In one
test with a radio using three AA lithium batteries, run time in RX
mode was two WEEKS continuous.)
Though very reliable electrically, durability is a concern, as most
equipment is built with light plastic cases and no waterproofing. Cost
is generally $25-$40 per unit with features of single-v.-5 channel and
voice-operated switching accounting for the difference. Note that
kiddie  walkie-talkies also operate on this band but the recievers of
such radios are worthless. 
Due to the proliferation of small, inexpensive 2-way radios for this
band, there is no realistic hope of private communications-indeed,
it's entirely possible that  this band will become so crowded as to be
useless in the event of an emergency.  
There are no standard frequency uses or nets on this band. Considering
the limited range, the primary use will likely be for tactical
communications among a small group, such as coordinating camp
activities. One group sends a scout ahead in diffcult terrain while
the rest of the backpacking party waits, with the scout calling back
if the path taken is viable; this saves  hours of useless
backtracking. 
 A secondary use is to place a radio with volume set on maximum on a
pack that is cached in a well-camoflaged environment. The squelch
keeps the  radio quiet, but another radio can transmit sounds allowing
the user to home-in on the hidden pack. 
The 49 MHz band is smack-dab in the middle of the VHF-low band (30-88
MHz, 25 KHz channel spacing) that armies world-wide use for primary
tactical communications. It should be no surprise then that there's
quite a variety of ground-based, airborne, and satellite-based radio
equipment dedicated to intercepting, direction-finding, and jamming
these frequencies,  which include the 49 MHz band.
Theoretically, consumer 49 MHz radios and military VHF-low radios
should interoperate. However, the reality is that only some military
radios operate with narrowband FM, and the tuning steps of the radios
are 25  KHz at best, frequently placing them  off-channel.  Newer
tactical radios, such as the US Army SINGARS, are usually operated in
frequency  hopping mode, in which there is no hope of interoperability
(such radios can tune to single channels, however.)
Although highly susceptible to interception and direction-finding, in
practice the range of consumer radios on this band is so limited that
this highly unlikely to occur unless a party is expressly seaching for
the signal in the immediate area; the short range also makes these one
of the few radios immune to satellite-based DF. In urban evironments
there are litterally hundreds of competing signals on the same
frequency, making interception  and DF difficult. Note that in
scenarios involving military conflict, operational jammers could make
these radios unusable at tens of miles away, and these radios are
likely to be unintended victims--jammed simply because they re in the
middle of a military band, and not due to overt intent.
One group known to us has primary communications based on 49 MHz
radios. The limited range and extremely low power consumption were
keys, along with the fact that the group stays close together 100% of
the time were factors that lead to the decision.
       
1750 Meter  Lowfer  Band
In the US, the 1750-meter band allows radios to operate with 1 Watt of
power into a 50  long transmission line/antenna system at frequencies
in the 170 Khz (that s 0.170 MHz) range with no license. This is a
*really* low  frequency. 
Equipment for 1750 meters is generally as small as one wants to build
it--there are only a few commercially built radios for this band,
generally the same size and weight as a larger mobile CB radio. Power
consumption is quite low, with about 3 watts peak for TX and hundreds
of milliwatts at  most for RX. Cost is generally no more than $200 for
a top-end commercial built radio.
Antennas are inefficient--and large, since the 50  limit really needs
to be exploited for the radio to work--and communication is not very
reliable at  long ranges, but at short ranges (a few miles) at night,
when the noise level is low, 1750 meters is reliable; at night during
the winter, it provides the greatest range, with semi-reliable
contacts at 100s of miles. During the summer this band is plagued with
static and isn t very reliable. T
he 1750 Meter band is a (barely) plausible survival radio band only if
it's used for a network among users that are located near each other.
There are a few experimenters on this band that perform low-rate data
communications using exotic modulation methods, but most prefer morse
code or SSB. There are no regularly monitored channels or survival
networks in operation, though some radio enthusiasts in California do
have a regular net.
 It is, however, worth noting, that some caving and spelunking
enthusiasts also sometimes use this band , as low frequencies have
some limited ability to penetrate obstacles such as the ground.

There s one survivalist of note that does use this band: the U.S.
Government. A special high-survivability data network known as the
ground-wave emergency network, or GWEN, can be heard between 150
and 170 KHz with a repetitive noise that sounds like a cross between a
hiss and a crunching sound. This network is intended to survive a
massive nuclear strike and provide low-data-rate post apocalyptic
communications.
Low frequencies are so easy to direction find that they are the basis
of the irst radio-navigation system used for aircraft and ships.
Starting at about  200 KHz, there are thousands of low-power
non-directional beacons (NDBs). Automatic-direction-finding (ADF)
radios tuned to an NDB indicate their direction with high accuracy,
and many ADF recievers are capable of tuning the 1750 meter band.

On the plus side, although direction-finders work really well here,
the low power and low frequency of the 1750 Meter band make it
effective for covert communications; few recievers tune this low, and
even fewer people even bother to listen. Due to the inefficiencies of
the antenna system  jamming is difficult, and there is no known
deployed jamming equipment capable of disrupting this band.
        
Micropower AM and FM
Also permitted under part 15 is low-power (100 milliwatts) AM
transmitters with a 10  antenna restriction on the same band as
broadcast  AM radio. The AM band shares many characteristics and
difficulties of the 1750-meter band.
Equipment is generally always hand-made, usually from AM broadcast
kits. Receivers can be cheap AM recievers, but a viable communication
system will likely use a sensitive mediumwave/shortwave radio
reciever. Cost of  the transmitter can be as low as $20, the reciever
$5 to $5000. Transmitter size is generally the size of a small mobile
CB, about 2  x 6  x 6 . Power consumption is minimal, under 1/2 watt.
Reliable reception ranges of a 1/4 mile or so are common, though with
good receivers and quiet band conditions (at night, during the
wintertime) on an unoccupied AM channel (rare in its own right) ranges
of 100s of miles have been obtained.  
Signals are easy to direction find (indeed, many aircraft ADF systems
also tune the AM radio band) and it s trivial to jam weak-signal
reception in the AM band when mother nature isn t doing it herself
with thunderstorms. 
No nets are known to use micro-power AM, though some pirate-radio
broadcasts violate the FCC s power specification and some of these
transmit vaguely survival-related gloom-and-doom conspiracy radio
programming. This (with legal power, and probably better, community-
related programming, of course) is probably the only viable use for
this band in a survival context (weak as though that may be.)
        
Micropower FM stations are also permitted, but the large bandwidth and
low power allowed makes micropower FM even more useless than AM.

(1)Licensed/Regulated Services
  (a)Amateur ( Ham ) Radio
        6-Meter Band
The six-meter band (50-54 Mhz ham band) is considered sort of a
"schizophrenic" band, that can't make up its mind whether to be a
worldwide/distant contact band or a local VHF band. It generally has
been known to be used as both of these. The use of this band is
primarily a local phenomenon-extremely popular in some areas and
completely silent in others.
        2-Meter Band
2 Meters (144-148 Mhz.) is one of the most commonly used bands in the
United States. Frequently these days, when a ham buys his first radio,
it's a mobile or  handheld 2-meter FM transceiver. SSB and CW are
rarely, but occasionally used on  this band. However, 2M is a favorite
for amateur radio satellite and amateur Earth-Moon-Earth
communications, and for technical reasons these methods require the
use of SSB or CW rather than FM.

MF/HF Bam Bands:
In the United States,   ham radio bands exist at 1.8MHz, 3.5MHz, 7MHz,
10.1MHz, 14MHz, 21 MHz, 24MHz, and 28 MHz. These bands are all capable
of long-distance communications, depending on atmostpheric and sunspot
conditions, and have all been used for worldwide/international
communication. The most common emissions modes are CW (Morse Code) and
Single Sideband, but certain data communications are also used.
Equipment for these bands is all over the range in terms of price and
complexity- low-power CW-only single frequency transmitters can be
built for $20, and high end all-band all-mode transceivers can be
bought for several thousand dollars.
  
  (1)Commercial Carrier and Emergency Services

Cellular Phones
A Cellular phone is essentially a low-power UHF transceiver. When a
call is made, the phone signals a fixed station called a 'cell.' The
cell transfers the signals between the radio waves and thephone
exchange. (A gross oversimplification, but detail is not required here
Cell phone conversations are not private, any more than any other
radio conversation. Technically, the law says that they may not be
monitored, but this law is unbelievably easy to violate-scanners able
to pick up cell frequencies are not sold to civilians any more, but
they can be built.
Cell phones also depend upon a working cell. A power outage for an
extended period could result in shutdown. Also, cells can be
overloaded. In the event of a disaster, a cell can handle a given
number of calls-that number plus one risks overloading the cell and
causing it to shut down completely. 

Paging
Paging is essentially a method of one-way radio communication. An
individual makes a telephone call to a given phone number, and is
prompted to enter a message. This message is then sent out over VHF or
UHF radio to a specific pager. Some paging service allows the display
of phone numbers. Others actually permit one to email a message to a
pager. 
This service has an advantage, in that it can discreetly summon one to
check in or go somewhere as needed, but is dependent upon a network of
transmitter towers and phone lines, and therefore might not be fully
functional in a disaster.

 a)Radio Operation and Procedures
A radio-based communication systems depend on two main elements to
work: operational radio hardware, and proceedures that allow the
sender and reciever to communicate. 

  (1)Radio Equipment, Antennas, and Propagation
Introduce the decibel. The decibel--or dB--is a comparative
measurement, that is, there s something measured against a reference.
The decibel allows a very wide range of signal power to be represented
with small, manageable numbers:

	Power Change	Decibels 
	2X		3dB
	100X		20dB
	1,000,000X	60dB
	0.5 X		-3dB
	0.000001X	-60dB

Things that increase a signal are usually called ãgainsä and things
that decrease a signal s strength are calles ãlosses,ä and both are
usually measured in dB, with gains being positive and losses negative.
Note that if we compare power to a fixed reference, such as a 1 Watt
or one milliwat, the dB can also be a measurement of actual power; a
transmitter with a 20dBW output, for example, has 100 Watts of power.

There two major factors that determine total radio performance, known
as station gain (what the equipment does) and path loss (what the
environment does to the signal between the stations.) 
It may seem confusing, but it s as simple as this: If station gain is
greater than path loss, you can communicate, otherwise, you can t. If
you can t communicate, you need to fix one or more parts of the radio
system until you have enough station gain--use more power, a more
sensitive reciever, better or higher antennas. 

Station Gain Factors			Good Base SSB CB
Transmit power				+10dbW (12 Watts)
Transmitting antenna height gain		+3db
Transmitting antenna gain			0dB
Recieving antenna height gain		+3dB
Recieving antenna gain			0dB
Reciever sensitivity			+149dB (-149dBW)
Total Station gain				165dB

The ultimate goal of the radio system is to get a signal to the
reciever that s stronger than the background noise, so the signal can
be heard. This is known as signal-to-noise ratio, and reciever
sensitivity is usually stated as the lowest power level that will
result in a given signal-to-noise ratio, typically 10dB. Note that the
reciever sensitivity is actually how much a signal can be reduced
before it can t be heard (-149dB) but it counts as a positive, as we
have 149dB in our station gain ãaccountä that we can lose before we
can t hear a signal anymore. 

The path loss is how of the signal is reduced by the
environment--distance, air, mountains, water vapor. Distance alone
reduces the signal at a rate of the square of the distance--a signal
two miles away is one-quarter the strength of a signal one mile away,
just because of the distance. Path loss varies (just a little bit)
with the frequency used until one gets to microwaves, where path loss
jumps quite a bit. Under ordinary conditions between two stations on
average terrain, path loss goes this way:

Frequency	10 Miles	 	25 Miles	50Miles
27 MHz (CB)	-135dB		-152dB		-174dB
144 Mhz (2M  )	-134dB		-157dB		-175dB

For a good SSB CB radio, we have 165dB of station gain, and we can
communicate as long as path losses are less than this; on average
terrain, this is somewhere between 25 and 50 miles. Note that if the
antennas used are poor and low to the ground, this will change things
considerably, as we ll see in a few paragraphs. 
In situations where the signal is bouncing around--such as shortwave
radio signals--the both loss includes both distance and the efficiency
that the signal is reflected; when conditions are good, this
reflection efficiency can be 100%, and only the distance matters.
Likewise, if a satellite is used, the path loss is pretty much a
result of just the distances between the ground stations and the
satellite involved. Distance-only path losses run about -110 dB for
100 miles, or a typical low-earth orbit, and -151 dB for 22,500 miles,
or geosyncronous orbits. No place on earth is more than 12,500 from
any other location, so the path loss for a perfectly reflected
shortwave signal is somewhere in-between.

Not that it s done, but our 165dB of station gain is quite a bit more
than the 151dB path loss of a geosynchronous satellite, so it s
trivial for the satellite to ãhearä a SSB CB or a 2-Meter Amateur
radio. Indeed, several emergency systems depend on this: simple 1/2
watt emergency-radio beacons are detected with low-earth orbit
satellites, and the newer 5-watt beacons are detected by geosyncronous
weather satellites.

(1)Basic Radio Antennas
Antenna Effectiveness
Antennas can be measured by listening to a ãstandardä transmitter on
the frequency of interest, and changing the antenna and noting the
changes in the signal. Higher-end radios have meters that show
relative signal strength, using numbers of 1 to 9 (S1...S5...S9) and
then dB over S9; each ãS--unitä is typically 6dB. Using a calibrated
reciever, we did measurements of a local weather station (near the
amateur 2-meter band) to illustrate several antennas. We used the
ãbestä antenna (which isn t very good at all, actually) as a
reference, and then compared several portable antennas:

Antenna		Sig. Strength	dB	% Signal
Discone at 20 feet		S9	 0db	100%
1/2 Wave Rod 6 		S5	-24db	 40%
Rubber duck, 6 		S3	-36db	 2.5%
Doing the same thing at CB frequencies:
Antenna		Sig. Strength	dB	% Signal
Dipole at 20 feet		S9	 0db	100%
Rubber duck, 6 		S0	-54db	 .0004%

Poor antennas will reduce station gain; indeed is we use the SSB CB
example where we had 165 dB of station gain, and change the antennas
used to ãrubber duckä antennas, the station gain plunges to  just
51dB, not even enough to cover five miles! What these measurements
show is that antennas can compromise perfectly good equipment, and
that it takes a good antenna for a radio to work well. 
There are several types of antennas that are easily built with wire or
stiff metal rods that are suitable for survival use and are also
ãgoodä antennas. As a general rule, if you want maximum range and
station gain, use a ãgoodä antenna and place it as high as possible,
including climbing up mountains or hills.

(a)1/4 Vertical
This is perhaps the simplest antenna. Basically, it's a vertical rod
or stiff wire fed by a feed line at the bottom and cut to about one
quarter of the desired wavelength. It radiates uniformly in all
directions, and is the most common type for handheld and
vehicle-mounted radios. 

(b)Dipole
Another simple antenna. Basically, it consists of two wires pointed in
opposite directions, and either horizontal or sloped. This antenna is
most commonly used for Medium- and High-Frequency ham radio and
shortwave listening (1.8-30 Mhz). It radiates most strongly in a
direction perpendicular to the long axis of the wires.

Quads and Yagis
Quads and Yagis are two types of directional antennas. A Yagi has a
center element, called a driven element, which is connected to the
feed line from the transmitter. This element is cut to roughly one-
quarter of the desired wavelength, and mounted on a horizontal boom.
Then, slightly shorter elements, called "director elements" are cut
and mounted on the boom on one side of the driven element. Slightly
longer elements, called "reflector elements" are cut and mounted on
the other side, and the whole antenna is generally mounted on a
rotateable mount. These types of antennae tend to be highly
directional, favoring the direction towards the director elements, and
are frequently used for HF, VHF, and UHF ham radio stations.

  (1)Signal Operating Instructions and Radio Nets
Signal Operating Instructions (SOI) is the military name given to a
whole host of methods and proceedures to communicate; essentially, SOI
is a protocol of behavior for people and equipment to communicate
successfully.

The single most imporant thing to remember is that that it takes
someone listening for communications to work, and the best radios in
the world are useless if no one hears you call for help. Establishing
or connecting to a radio ãnetä of listeners--making sure that someone
is out there listening for you--is the single most important step to
take in radio communications. Period.

Schedules
It s impractical for most people to listen to radios continuously, so
having a schedule for stations on your ãnetä to listen makes radio
communication practical. Either use a published schedule, or a regular
interval (every day at 7pm, for example) for the ãnetä to come
on-line.

Guard Channels
All radio users need to be on the same frequency to communicate. A
special ãlisteningä frequency makes monitoring easy; for example, on
CB radios, channel 9 is used only for emergency traffic, so you can
listen to this channel and know if you hear something, it s important.
In many areas, there are amatuer radio repeaters with a feature known
as LiTZ (Long-tone-zero) which is used to turn on recievers of regular
listeners, for when help is needed. Your radio ãnetä should have a
guard channel to listen to when the net isn t active, and a one or
more net channels for when it is. (Depending on other factors, these
channels may be changed regularly or not.)

Codes
In general, the use of codes, ciphers, and other encryption on most
radios is illegal in the United States if the intent of the code is to
obscure the meaning of a message. There are legal uses for codes  in
CB and ham radios-see below under "Brevity and Message Coding"

Authentication
Authentication is the art of verifying that all people in a given net
are people who have legitimate access, for example through the use of
unannounced questions. For example, during World War Two, it was a
popular perception that no German soldier would know anything about
baseball. As a result, American GI's would frequently quiz each other
about baseball trivia to be sure that everyone present was in fact an
American.

Brevity and Message Coding
Radio communication takes time and bandwidth. Certain codes have
become agreed-upon conventions to compress a relatively large amount
of information into a relatively small amount of space. For example,
almost everyone who listens to a CB or to police radio has heard the
"Ten codes" in which a sender may say "Ten-four" and be understood by
everyone listening as having said "Your message is acknowledged"

SOI Spares
Having extra copies of your Signal Operating Instructions can be a
double-edged sword. On one hand, if your SOI is at all complex or
elaborate, losing your only copy could be crippling. However, if your
net's integrity depends upon not having your procedures widely
known,an extra SOI is a copy of the SOI waiting to fall into the wrong
hands.

1.Visual Signals

Morse code by light
Ships carry a set of blinker lights for communication by morse code.
These lights are essentially searchlights fitted with shrouds or
shutters that can be quickly opened or closed.

Semaphore
In the days before wired telegraphy, a code was used to send messages
over long distances called semaphore. Basically, the sender stood atop
a hill holding a brightly colored flag in each hand. He would face the
receiving station and raise his arms up out to his sides, and the
angle at which he held his arms would signify a given numeral or
letter.

three-in-a-row rule (whistles, gunshots...)
  In general, three of any signal repeated at a regular interval
signifies distress. For example, a hunter who is lost can fire three
shots in the air a few seconds apart. Theoretically, anybody in the
vicinity will hear the three shots and realize that the hunter is in
some sort of distress, and will be able to figure out the direction to
search from the sound of the shots.
1.Postal Modes
OK, it s here for completeness, but it s worth mentioning hiding
messages in ordinary communications. Messages which aren't
particularly time-sensitive can be sent inexpensively, and with some
relative degree of anonymity.  
Grown men do not need leaders-Cactus Ed.
Remove the obvious thing from my sig to reply
