This lesson provides
an overview of operations in a radio network, or "net" environment.
It sets the stage for the following lessons, which present various aspects
of
net operation and message handling in greater detail. This lesson contains
information that is appropriate for net operations in a variety of
settings,
and is
representative of nets around the country. Local procedures may vary slightly.
Student preparation
required:
Learn the following definitions:
Net: A group
of stations who gather on one frequency, with a common purpose. The net
provides
a structure and organization to allow an orderly flow of messages.
Net Control Station
(NCS): The station in charge of the net and directing the flow of messages
and general communications.
Formal Messages:
Written messages that are sent in a standardized format.
Informal or Tactical Messages:
Brief verbal or informal written messages, intended for direct and immediate delivery.
Traffic: A term
referring to messages sent over Amateur Radio, usually formal, written messages. More generally, any messages or activity on a particular frequency.
Pass: to send
messages from one station to another.
Third Party Traffic:
Messages transmitted on behalf of a person or organization other than a licensed
Amateur Radio operator. This term also applies to when a person other than
a licensed operator is allowed to use the microphone.
Liaison Station:
A station responsible for passing messages between different nets.
Information:
What is an Emergency
Net?
The purpose of any net
is to provide a means for orderly communication within a group of stations.
An "emergency" net is a group of stations who provide communication to one
or more served agencies, or to the general public, in a communications emergency.
An emergency
net may be formal or informal, depending on the number of participants and
volume of messages.
Net Formats
Directed (formal) Nets:
In a directed net, a "net
control station" (NCS) organizes and controls all activity. One station
wishing to call or send a message to another in the net must first receive
permission
from the NCS. This is done so that messages with a higher priority will be
handled first, and that all messages will be handled in an orderly fashion.
Directed
nets are the best format when there are a large number of member stations.
(Be careful not to confuse "formal nets" with "formal messages." There
is no definite link between the two. A formal net may handle informal messages,
and vice versa.)
Open (informal) Nets:
In an open net, the NCS
is optional. Stations may call each other directly. When a NCS is used at all,
he usually exerts minimal control over the net. The NCS may step in when the
message volume increases for short periods, or to solve problems and keep the
net operating smoothly. Open nets are most often used when there are only a
few stations and little traffic.
Types of Emergency Nets
Emergency nets may have
different purposes, and a given emergency may require one or more of each type
of net. During a small operation, all functions may be combined into one net.
A traffic net
handles formal written messages in a specified (i.e. ARRL) format. The nets
operated by the National Traffic System (NTS) are an excellent example
of traffic
nets.
ARES or RACES traffic nets may be directed or open depending on their size.
Tactical nets
are used for real-time coordination of activities related to the emergency.
This is a faster-moving, often less formal operation. Messages are usually
brief, and frequently unwritten. A tactical net usually has a NCS, but may
be directed or open. The NCS may have other duties or responsibilities as
well.
A "resource" or "logistics"
net
may be needed to acquire resources and volunteers and handle assignments.
It is usually a directed net. Resource nets accept check-ins from arriving
volunteers,
who
are then directed to contact an appropriate station or to proceed to a specific
location. It might also be used to locate needed resources, such as equipment, food, water and other supplies for ecomm volunteers.
An information net
is usually an open net used to collect or share information on a developing
situation, without overly restricting the use of the frequency by others.
Net members send updated local information as needed, and official bulletins
from the served agency may be sent by the NCS (if the net has one), an agency
liaison station, or an Official Bulletin Station (OBS). The NCS and many of
the participants monitor the frequency, but a "roll call" is seldom taken and stations may not be expected to check in and out of the net.
The operation of an information net also serves as notice to all stations
that a more formal net may be activated at any moment if conditions warrant.
A good example is a SKYWARN weather net activated during a severe storm watch.
Checking Into an Emergency
Net
There are two situations
where you will need to "check in" to a net.
When you first join
the net.
When you have messages,
questions, or information to send.
If you are part of the
organization operating the net, simply follow the instructions for checking
into directed and open nets as discussed below.
To become part of a directed
net, listen for the NCS to ask for "check-ins" and listen to any specific
instructions, such as "check-ins with emergency traffic only." At the appropriate
time, give only your call sign. If you have a message to pass, you can add,
"with traffic." If it is an emergency message, say "with emergency traffic."
The same is true for stations with priority traffic. Wait for a response before
offering more information. Checking into a directed net when the NCS has not
asked for check-ins is usually considered a bad practice. However, if a long
period passes with no request, you might wait for a pause in the nets activity
and briefly call the NCS like this: "Net control, W1FN, with traffic."
To check in to an open
net for the first time, briefly call the net control station
as above. If there appears to be no NCS, call anyone on the net to
find out if anyone is "in
charge" and make contact with them. If you are already part of the net and
have a message to send, simply wait for the frequency to be clear before calling
another station, .
If you are not part
of the organization operating the net, do not just check in and offer to
assist. Listen for a while. Be sure you have something specific to offer before
checking in, (such as the ability to deliver a message close to your location
when none of the regular net members can). If they really do seem to need help
that you feel you can provide, you might check in briefly to ask if they have
a "resource" net in operation, then switch to that frequency. If not, make a
brief offer of assistance to the NCS.
Do not be too surprised
if you receive a cool reception to your offer of help. It is usually nothing
personal. Emergency nets are serious business. Most ecomm managers prefer
to deal with people with known training and capabilities, and with whom
they have
worked before. You may not have the experience, skills or official credentials
they require and they have no way of knowing what your true capabilities
are.
Some ecomm managers will assign you as an apprentice, logger, or as a "runner".
If you are given such an opportunity, take it! It is all good experience and
a great way to introduce yourself to the group. Better yet, become involved
with your local ecomm group now do not wait for the next disaster.
Passing Messages:
If you told the NCS you
have traffic to send when you checked in, he will probably ask you to "list
your traffic" with its destination and priority. After you send your list, the
NCS will direct you to pass each message to the appropriate station in the net,
either on the net frequency, or another frequency to avoid tieing up the net.
When moving to another frequency to pass the message, always check to see if
the frequency is in use before beginning.
When you are asked by the
NCS to send your message, the standard procedure is for the NCS to tell the
receiving station to call the sending station.
The entire exchange might
sound like this:
NCS: "W1AW, list your
traffic."
You: "W1AW, two
priority for Springfield EOC, one welfare for the Section net."
NCS: "Springfield
EOC, call W1AW for your traffic." Springfield
EOC: "W1AW, Springfield EOC, go ahead."
You: "Number 25,
Priority..."
(After you have
sent your messages to the Springfield EOC, the NCS will next direct the section
net liaison station to call you for their message.)
When you have finished,
simply sign with any tactical call sign and your FCC call.
(You will learn more about
messages and message handling and "emergency," "priority," and other precedences
later in this course.)
"Breaking" the Net
If the net is in progress,
and you have emergency traffic to send, you may need to "break" into the net..
Procedures for doing this vary from net to net, but the most common method is
to wait for a pause between transmissions and simply say, "Break, WA1ZCN." The
NCS will say, "Go ahead WA1ZCN," and you respond, "WA1ZCN with emergency traffic."
Checking Out of an Emergency
Net
Always
let the NCS know when you are leaving the net, even if it is only for a few
minutes. If the NCS believes you are still in the net, they may become concerned
about your unexplained absence. This could result in someone being unnecessarily
dispatched to check on your well-being.
There are three reasons
for checking out of (leaving) a net.
The location of your
station is closing.
If the NCS has given you directions to close the location, simply acknowledge
the request, and sign with your tactical call sign, if you are using one,
and your FCC call sign. If the order to close has come from a local official,
state that your location has been closed, along with the name and title
of the official who ordered it, and sign off as above. Long "goodbyes" only
tie up the net needlessly, and do not sound very professional.
You need a break and
there is no relief operator.
Tell the NCS
that you will be away from the radio for a certain length of time, the reason,
and sign with your tactical call sign, if you are using one, and your FCC
call sign.
You have turned the
location over to another operator.
Tell the NCS
that you have turned the station over to (give the new operator's name
and
FCC callsign), and that you are leaving. Sign with your tactical call sign,
if you are using one, and your FCC call sign
There are two special situations
to be aware of:
If you are asked by
someone in authority, such as a law enforcement officer, to move your station,
then move immediately and without argument. Notify the NCS of the situation
at the first appropriate opportunity.
If you are requested
by someone in authority to turn off your radio, or to refrain from transmitting,
do so immediately and without question. Do not notify Net Control
until you have permission to transmit again, and can do so safely. There
is usually a good reason for such a request. It may be an issue of security,
or it may be a potential hazard, such as an explosive devise that could
be triggered
by RF energy.
Levels of Nets:
Network systems are often
"layered" for greater operating efficiency. Some networks are designed to handle
messages within specific areas, and others to handle messages between areas.
Think of this much like you would the Interstate Highway System. Local messages
(cars) travel between destinations directly on local nets ( local roads).
When
a message has to go to a distant city, it is passed to a regional net (state
highway), and if it is really distant, to a long distance net (interstate
highway). At the other end it is returned to regional, then local nets for
delivery.
What has been just described is the extensive National Traffic System (NTS),
discussed further below.
A similar structure can
be used by ARES or RACES on a smaller scale. For instance, each city might have
a local FM net. A county net would handle messages going from city to city.
A section HF net would handle messages from county to county. Any net in such
a system could have "liaison" stations to pass into the NTS any messages that
need to travel out of the section.
The Nets of the National
Traffic System
The National Traffic System
(NTS) was created by the ARRL and authored by George Hart, W1NJM in 1949 to
handle medium and long distance traffic. In an emergency, The National Traffic
System can be used to provide a link from the area impacted by the emergency
to the outside world. The National Traffic System is a hierarchical (layered)
set of nets, beginning at the local level with the Local nets and continuing
through the Section Nets, Region Nets, Area Nets, and finally the Transcontinental
Corps. Messages are passed by assigned "liaison" stations between various nets
as necessary to reach their final destination. These nets operate in carefully
designed "cycles" that allow a message to move smoothly and efficiently from
one net to the next across the country in 24 hours. Each message follows a pre-determined
path to its destination.
The details of NTS operation
are quite complex and well beyond the scope of this course. To learn more about
the NTS, visit the NTS section of the ARRL website or contact
your Section Manager or NTS Section Traffic Manager.
Non-Voice Nets
Emergency nets may also
use other modes of communication besides voice (phone). Traffic nets have
used
CW since the beginning of Amateur Radio, and it is still a viable option for
long distance formal traffic. High speed CW nets can actually handle more
messages
per hour than most voice nets. Packet communication on VHF and UHF is often
used for local communication where accuracy and a record of the message
are
required. HF digital modes such as AMTOR and PACTOR are used on long distance
circuits. Many groups are now experimenting with emergency communication
applications for newer modes such as PSK31 on HF and VHF/UHF bands.
The latest end-to-end message handling system to get the attention of the ecomm community is WinLink 2000, an automatic system that blends radio and Internet transmission paths to permit rapid and seamless email message transfer to stations anywhere on Earth. For most emergencies, it will be possible for stations in the affected area to link to a WinLink 2000 Pactor node outside the affected area, allowing rapid contact with the outside world.
Also new to ecomm, FNpsk is a novel Windows ® program designed to allow easy handling of ARRL format messges via PSK31. See the Reference Links section at the end of this unit for the Internet URL.
Most CW nets are directed nets. Packet nets are not generally directed by a human, due the automatic "store and forward"
nature of the mode, and are usually operated as open nets with no NCS.
Reference links:
To learn about NTS
in your area, contact your Section Manager (SM), or Section Traffic
Manager (STM). To locate your Section Manager (SM), see the ARRL Section
Manager List at: www.arrl.org/field/org/smlist.html.
FNpack - www.w1fn.org - a Windows® packet radio terminal program designed for ecomm.
FNpsk - www.w1fn.org - similar to FNpack, but for PSK-31
Review:
Large nets are usually
directed (formal) nets with a NCS in charge. Smaller nets may be "open"
(informal), and a NCS is optional. Nets can serve many purposes, including passing
formal messages, handling logistics, or passing informal tactical messages.
Large emergencies may require more than one of each type of net - small emergencies
may have one combined net. Medium and long distance messages are often handled
by the National Traffic System (NTS).
Now click on the
Activities button and proceed with the Student Activities, which are required
before moving to the Questions (click on the Question button). Upon completion
of these Questions, go to the next Learning Unit.
