Idaho Amateur Radio
Emergency Service
   
NET Operation Overview - Table of Contents
Overview

An Amateur Radio NET, short for network, is a structured gathering of Amateur Radio operators. A NET may have as simple a purpose as to organize the hand-off of a conversation from one radio operator to another in an orderly manner. More complex NETs exist to pass traffic and facilitate on-air activities that advance the preparedness of a radio operator to perform the functions being promoted by the net activity.

The purpose of the NET is to introduce order into communications among many stations. The benefit of ordered communications is that efficient use of bandwidth (i.e. time on channel) is achieved by avoiding situations where non-ordered simultaneous communications by multiple stations results in excessive consumption of bandwidth when messages need to be repeated.

Predominantly, ARES uses a Directed NET format to organize communications, with ARES nets open to all Amateur Radio operators.


Directed NETs

A directed NET enables the NET Control Station to prioritize requests for resources, to efficiently handle traffic from multiple stations, and to keep a centralized log of requests and responses.

A directed NET introduces order by designating a NET control station (NCS) and by introducing protocols into the NET operating procedures. The NET control procedures are usually scripted, where the script is published and used by all NET control stations in order to provide a consistent implementation of NET protocols.

A directed NET script often has the NET control station reading a preamble, which directs participating stations as to the protocols for participating in the NET. It is vital that participating stations adhere to the protocols of the NET in order to achieve efficient operation and use of bandwidth.

Net control procedures for a directed NET require that initial interaction between participating stations and the NET go through the NET Control Station. Any need for direct contact between two stations must be made through a request to the NET Control Station. Such requests should be made before or after the formal portion of the NET session and should not be made during the formal portion of the NET session.

Stations participating in a directed NET should answer promptly to avoid imposing delays to the formal portion of the NET session. Stations arriving late should not interrupt the formal portion of the NET but should wait until the formal portion of the NET is completed before contacting the NET Control Operator unless the NET Control Operator specifically calls for such contact through established NET protocols.

Directed NETs may be scheduled events or may occur as needed during a simulated emergency exercise or real emergency event. Scheduled NETs usually draw from a pool of designated NET operators and provide an opportunity to obtain training as a NET operator in a relaxed environment. Scheduled simulated emergency exercise NETs and non-scheduled emergency NETs, likewise, draw from a pool of trained operators, and implement the NET procedures according to a local or regional emergency communications plan.

Emergency NET operation may occur in any crisis where persons or property are at risk. Authority to declare an emergency lies with agencies and authorities outside of the Amateur Radio service. An emergency may require multiple NETs, with each NET fulfilling a different purpose. In such cases, there may be a central coordinating NET that is used to direct resources to the appropriate NET.


Emergency Communications Planning

Emergency communications planning should provide a framework for a call to action of Idaho ARES members. The framework should include a superset of local, district and statewide planning. Emergency coordinators should, at a moments notice, be able to determine what segments of the plan are appropriate for current conditions and activate those sections of the plan. Emergency planning should include:

Once a call to action has occurred, and Incident Commanders have requested Amateur Radio emergency communications services, a large portion of the burden falls immediately to the NET control operators.

No Amateur Radio operator should self deploy to the scene of an emergency. Amateur Radio operators who wish to volunteer services should check-in with NET control, providing a short transmission to indicate availability for service. Do not clutter the NET with detailed station information unless requested by NET control. Simply indicate your call sign and availability for fixed, mobile or portable operation as appropriate for your capabilities. The initial contact to NET control should simply be to announce your call sign during a lull in NET activity. Upon acknowledgement by NET control, then transmit your request to volunteer (e.g. K7QRZ volunteering portable HF and VHF/UHF capabilities - over).


Net Control Station

The NET Control Station (NCS) serves a critical position. NET control operators must be able to:

Bandwidth is the life blood of the NET. There is only so much traffic that can be handled on a given frequency over a fixed amount of time. The NET control station has the responsibility to make sure that the NET operates efficiently so that none of the available bandwidth is lost. Implied is that the NET control station must exhibit a level of competence that avoids loss of bandwidth. An inefficient NET control station can cause bandwidth to be lost on every transmission. Such loss of bandwidth can have a direct impact on risk to safety, life or property.


Communications Skills
Communications Goals

The goal of any communication should be to accurately communicate a message with brevity and clarity while adhering to NET protocols. Successful attainment of these goals results in:

Non-critical transmissions of a casual nature have no place in emergency NET operations. Although tolerated during scheduled directed NETs, such transmissions should be held until formal NET traffic has been completed.

A scheduled NET may utilize linked repeater communications infrastructure to expand the communications footprint and enable more stations to participate in NET operations. Such linking may be established through software scheduled mechanisms, including a scheduled severing of the link connections. Casual non-critical communications that are injected into the NET script can result in delaying formal NET traffic. Should the delay in formal NET traffic exceed the scheduled severing of the repeater links then outlying stations will be cut off from the formal NET traffic that occurs after the scheduled disabling of the repeater links. This makes it even more critical that informal traffic be held until the formal portion of the NET is completed so that all participating stations are able to communicate during the formal portion of the NET.


Plain Language

Message construction should use plain language, avoid the use of contractions, and omit any language that does not contribute to the meaning of the message being conveyed. Use of phonetics should be used whenever the spelling of a word may be in question. The use of jargon, including 10-codes, Q-signals and slang, should be strictly avoided. The only exception is that Q-signals may be used in a CW NET. Interaction with public safety, government and non-governmental agencies requires the use of plain language. Jargon may have no meaning, or worse, a different meaning than intended.


Phonetics

Where phonetics are used, home made phonetics should be strictly avoided while the use of standard ITU/ICAO phonetic alphabet should be used:


ITU/ICAO Phonetic Alphabet
Character Morse Telephony Pronunciation
A •- Alpha AL-FAH
B -••• Bravo BRAH-FOH
C -•-• Charlie CHAR-LEE or SHAR-LEE
D -•• Delta DELL-TAH
E Echo ECK-OH
F ••-• Foxtrot FOKS-TROT
G --• Golf GOLF
H •••• Hotel HOH-TEL
I India IN-DEE-AH
J •--- Juliet JEW-LEE-ETT
K -•- Kilo KEY-LOH
L •-•• Lima LEE-MAH
M -- Mike MIKE
N -• November NO-VEM-BER
O --- Oscar OSS-CAH
P •--• Papa PAH-PAH
Q --•- Quebec KEH-BECK
R •-• Romeo ROW-ME-OH
S ••• Sierra SEE-AIR-RAH
T - Tango TANG-GO
U ••- Uniform YOU-NEE-FROM or OO-NEE-FORM
V •••- Victor VIK-TAH
W •-- Whiskey WISS-KEY
X -••- Xray ECKS-RAY
Y -•-- Yankee YANG-KEY
Z --•• Zulu ZOO-LOO
1 •---- One WUN
2 ••--- Two TOO
3 •••-- Three TREE
4 ••••- Four FOW-ER
5 ••••• Five FIFE
6 -•••• Six SIX
7 --••• Seven SEV-EN
8 •••-- Eight AIT
9 ----• Nine NIN-ER
0 ----- Zero ZEE-RO

The use of phonetics introduces less impact to NET bandwidth than a repeated message and their use should be employed anytime clarity is in question.


Pro-words

Pro-words are used to introduce clarity when passing traffic. It is critical that all stations participating in a NET apply pro-words with the same definition applying to all stations.


Pro-words
Pro-word Definition
Affirmative Means Yes, I agree or permission granted.
Break Used to separate NTS message text from the address or signature block. Not to be used to interrupt a contact in progress.
Break-Break Used to indicate that you have emergency or priority traffic that must be handled immediately.
Check-break Used to indicate that you are pausing to verify copy of your message.
Clear Transmission completed, no response required.
Copy Used to indicate the transmission has been received.
Correct Acknowledgement that transmission was correct.
Correction Indicates that an error was detected and the transmission will resume with the last correct word.
Decimal Indicates a decimal point
Disregard An error has been made and the entire transmission should be ignored.
Figures Indicates that the following words are to be copied as numbers. Used to switch from Letters to Figures.
Go ahead Used to indicate a station may respond.
I Spell Indicates the word will be spelled phonetically.
Initial Single letter follows.
Letters Indicates that the following words are to be copied as letters. Used to switch from Figures to Letters.
Negative Used to indicate No, I disagree or permission denied.
Numbers Indicates that the following words are to be copied as numbers. Used to switch from Letters to Numbers.
Numerals Indicates that the following words are to be copied as numbers. Used to switch from Letters to Numerals.
Out Transmission completed, no response required.
Over Used to let another station know to respond.
Roger Used to indicate the transmission has been received and understood.
Say Again Used to request that the last message be repeated.
Say Again All After Used to indicate that the portion of the message after the indicated word should be repeated.
Say Again All Before Used to indicate that the portion of the message before the indicated word should be repeated.
Say Again Word After Used to indicate that the word after the specified word should be repeated.
Say Again Word Before Used to indicate that the word before the specified word should be repeated.
Stand-by Used to indicate that all stations should hold transmission until notified otherwise.
This Is Used to identify the station whose call sign follows.
Wait Used to indicate that all stations should hold transmission until notified otherwise.
Wilco Indicates that the command was understood and that the station will comply with the command.
XRay Used to indicate that a period should be entered at the end of the line just copied.


Tactical Call Signs

Tactical call signs are used to indicate the function of a station or the location of a station. Tactical call signs are useful in that new stations can enter the NET and establish contact without knowing the station’s FCC issued call sign. Tactical call signs should be used for all emergency NETs and public service NETs whenever any participating station is not familiar with other stations or their assignments, or whenever communications can be made more efficient by use of tactical call signs.


Station Identification

FCC regulations require that stations identify once every ten minutes and at the end of the last transmission, using the FCC issued call sign. This requirement is not negated by the use of a tactical call sign and a tactical call sign does not serve to replace the station’s FCC issued call sign for station identification purposes.

A recommended method of fulfilling the FCC identification requirement is to transmit your call sign at the end of an exchange.


Station Operating Habits

Amateur Radio operators are well advised to apply the operating procedures that are required for emergency communications into their daily station operation. Doing so will avoid habitual operation that does not conform to emergency communications requirements and will avoid any need to break bad habits should the need for emergency communications arise.

Avoiding jargon while employing the use of plain language in daily station operation will lead to a streamlined integration into emergency communication operation and ARES activities.


NET Operating Modes

Several operating modes are useful for NET and emergency communications operation. Each mode has its own advantages and application.


Morse


Voice


HF Digital Modes

Most HF digital modes only require an isolated sound card to interface the radio to the computer. Digital signal processing capabilities of current computer hardware render a Terminal Node Controller (TNC) unnecessary for HF most digital modes. Digital modes are ideally suited for:

The following table provides an assessment of the most popular and most capable digital modes that are available for emergency communications on HF:


HF Digital Modes
Mode Software FEC Performance
Windows Linux OS X
PSK31 FLDIGI
HRD
FLDIGI FLDIGI NO
  • Prone to drop characters, copy characters incorrectly, insert characters that were not sent.

  • Not appropriate for emergency communications where perfect copy is required.

  • Slow performance at 31 baud.

  • RSID exceeds the bandwidth of the transmission and is unnecessary, or even discouraged, with this easily identifiable and tunable mode.

  • Does not support email or email bridging to internet infrastructure.

  • Although the most popular mode on HF, this mode is not suitable for EMCOMM where lossless copy is a requirement.

MT63-1K FLDIGI FLDIGI FLDIGI YES
  • Uses 1KHz bandwidth.

  • Copy largely unaffected by noise, interference or fading.

  • Fast operation at 100 WPM. Can lose up to 25% of signal and still copy.

  • Best used with an RSID on transmission to enable easy tuning of the signal.

  • Heavily used by MARS and CGAUX due to robustness and ability to provide lossless copy.

  • Latency makes MT-63 undesirable for keyboard communication while latency is less of an issue for transfer of large sections of text.

  • Ideal for lossless transmission of formatted messages, such as evacuation rosters, FEMA formatted messages, Red Cross formatted messages and Hospital formatted messages.

  • Does not support email or email bridging to internet infrastructure.

  • Center frequency within receiver passband is 1 KHz for standardized operation, with modulation occurring between 500 Hz and and 1.5 KHz.

  • Narrow Band Emergency Messaging System (NBEMS) recommends this mode for HF only.

MT63-2K FLDIGI FLDIGI FLDIGI YES
  • Same benefits as MT63-1K.

  • Supports 200 WPM data rate.

  • Wide bandwidth may require filter adjustment.

  • Can lose up to 25% of signal and still copy.

  • Does not support email or email bridging to internet infrastructure.

  • Center frequency within receiver passband is 1.5 KHz for standardized operation, with modulation occurring between 500 Hz and and 2.5 KHz.

  • Narrow Band Emergency Messaging System (NBEMS) recommends this mode for VHF and UHF only.

Olivia 16/500 FLDIGI FLDIGI FLDIGI YES
  • Speeds of 20 WPM.

  • Tolerates signal to noise ratios of -13 dB.

  • Requires bandwidth of 500 Hz.

  • Best used with an RSID on transmission to enable easy tuning of the signal, although the mode is tolerant of mis-tuning.

  • Does not support email or email bridging to internet infrastructure.

  • Narrow Band Emergency Messaging System (NBEMS) recommends this mode for HF only.

Olivia 16/1000 FLDIGI FLDIGI FLDIGI YES
  • Speeds of 40 WPM.

  • Tolerates signal to noise ratios of -10 dB.

  • Requires bandwidth of 1 KHz.

  • Best used with an RSID on transmission to enable easy tuning of the signal, although the mode is tolerant of mis-tuning.

  • Does not support email or email bridging to internet infrastructure.

  • Narrow Band Emergency Messaging System (NBEMS) recommends this mode for HF only.

Olivia 16/1000 FLDIGI FLDIGI FLDIGI YES
  • Speeds of 24 WPM.

  • Tolerates signal to noise ratios of -12 dB.

  • Requires bandwidth of 1 KHz.

  • Best used with an RSID on transmission to enable easy tuning of the signal, although the mode is tolerant of mis-tuning.

  • Does not support email or email bridging to internet infrastructure.

WL2K RMS Express
WinLink 2000
Winmor
    YES
  • Networking capabilities and interoperability with the internet, including email support, make this mode very compelling.

  • Due to incompatibility with non-Windows operating systems, use of this mode may exclude Amateur Radio operators from participating and may impose a reduction in man-power.

  • For peer-to-peer communications, other modes may be more suitable as other modes do not impose an automatic reduction of man-power resources due to operating system incompatibilities.

  • For email capabilities that bridge to the internet, in a Windows only environment, no other mode provides equivalent capability.

  • Dependencies on the current .net framework require a current version (i.e. post XP) version of Windows.

  • Contingencies listed on the WinLink web-site are not viable for non-Windows operating systems because lack of concurrent access to other applications (BootCamp on Macintosh) or result in memory leaks that adversely impact system performance (Virtual Machine under Mac OS X).

  • The Department of Homeland Security appears to favor this mode. However, to fully realize its potential, and negate any negative impact on ARES staffing that is imposed by a lack of interoperability with non-Windows operating systems, this mode needs to be ported to native versions capable of running on operating systems other than Windows (i.e. Mac OS X & Linux).


Please see the Tutorial section under the Resources menu for further information regarding these digital modes, the software available that supports these modes, and operation on these modes.


Repeaters & Repeater Networks

For local and district wide communications, VHF/UHF repeaters and networked repeaters may be the most commonly used means for communications. For the Technician class licensee, with no operating privileges below 10-meters, this is definitely the case.

Repeaters extend line of sight propagation by raising the effective elevation of all stations using the repeater. Further, when repeaters are linked, the effective coverage footprint is further extended to include the composite of the coverage footprints of the constituent repeater systems.

Repeater systems usually implement back-up power systems that provide a time limited operating capability in the event of a primary power failure. Some repeater systems have the transmitter operate at a lower output power level when running on battery back-up power, which provides for a longer operating period when compared to full power operation. Repeater systems employing back-up generators are able to operate on back-up power with no compromises.

Repeaters may be linked using radio frequency linking, land-line linking or voice over internet protocol (VOIP) linking. Radio frequency linking is limited to the line of sight propagation from the link radio location. Land-line linking is not very common. Voice over internet protocol linking, such as is available with EchoLink, Internet Radio Linking Protocol (IRLP), MotoTRBO, and others.

Use of VOIP linking enables a repeater system coverage footprint to be extended well beyond the local area to provide regional, statewide, nationwide and even international coverage.

Some VOIP protocols, such as EchoLink, are also supported by application software that runs on Windows, iOS and Android devices. Such software enables individual stations, that are out of the repeater coverage footprint, to connect to the repeater via the internet. This enables the station to participate in ARES activities that would otherwise be unaccessible. Note that stations connecting in directly to a repeater should familiarize themselves with the operating procedures for that repeater prior to making a connection.

Repeater linking, particularly radio frequency repeater linking, introduces significant latencies as the CTCSS or DCS decoder at each receiver in the signal path requires sufficient time to decode the CTCSS or DCS prior to keying the transmitter. The typical delay is approximately 200 milliseconds per receiver / transmitter pair along the signal path. This requires that stations operating on the repeater network system key their transmitter for approximately 1/2 second prior to speaking to enable all transmitters in the signal path to come up. Some repeater systems implement audio delay lines to mitigate this issue, and when implemented, the delay problem moves from the front of the transmission to the back of the transmission, requiring stations to wait for 1/2 second after the transmission ends before the next station should transmit. The delays are cumulative for each hop in the network and the required delay may be network dependent. Stations should consult with the repeater system or repeater network operator to determine the required delays for a given system and whether the delay is required at the front end or back end of the transmission. Note that inter-tied repeater systems may have opposing requirements, requiring delays on both the front end and back end of a transmission.

Repeaters are regulated under CFR 97.205. The lowest frequency that can be legally used for a repeater is 29.5 MHz. Providing access to a transmitter on a frequency below 29.5 MHz falls outside of the regulation. Although some radios provide capabilities that exceed the limits of legal operation, it is the responsibility of the Amateur Radio operator to ensure that their operation falls within the regulations.

Although Technician class licensees have no operating privileges for direct transmission using the 10-meter FM repeater band (i.e. 29.5 to 29.695 MHz). Any Technician class license that access a repeater through a repeater receiver that falls within their frequency allocation, and where that repeater retransmits on the 10-meter repeater band, the Technician class licensee is not in violation of the regulations. This could occur with a remote base or where a repeater operating on 6-meters on up is linked to a 10-meter repeater.


HF Propagation

HF propagation options for NET and emergency communications requirements consists of Ground Wave propagation, Near Vertical Incidence Skywave (NVIS) propagation and Low Angle Long Hope Propagation.


Ground Wave HF Propagation

Ground Wave HF propagation is generally limited to 60 miles or less. Terrain can significantly shorten the distance. For communications on the long end of HF ground wave capabilities, HF may be viable if VHF / UHF repeaters are not available. For communications on the short end of HF ground wave capabilities, VHF / UHF simplex or repeater operation will almost always provide more reliable communications.


Near Vertical Incidence Skywave (NVIS) HF Propagation

Near Vertical Incidence Skywave (NVIS) propagation provides communications capabilities that overlap ground-wave coverage and extend up to 600 miles approximate. NVIS requires a high angle of radiation, usually achieved by installing a horizontal dipole antenna no higher than 1/8 wavelength above the ground.

NVIS operation has been compared to pointing a shower head at the ceiling and having the water droplets saturate the area immediately surrounding the shower head. NVIS propagation is in heavy use by military forces world-wide, MARS and CGAUX HF stations, and by HF land mobile stations operated by government agencies at the federal, state and local levels to provide robust communications capabilities.

NVIS does not require a high power lever and is reliable at power levels well below 100 watts. Amateur Radio NVIS is particularly suited for 60-meter operation, where power levels must not exceed 100 watts effective radiated power (ERP), and on both the 75-meter and 40-meter bands. Please refer to the HF NVIS Band Selection tutorial that is available under the Resources menu.


Low Angle Long Hop HF Propagation

Short range low angle long hop HF propagation intersects with the longer range NVIS propagation, and can extend beyond the national level to international applications. This propagation may be required for a national event but is generally not required for regional communications, and not useful at all for local communications.

Should low angle long hop HF propagation be required, propagation prediction can be performed between two points using VOACAP.


NET Operating Resources

Always seek to obtain a copy of the NET script that is used by the NET Control Station (NCS). This document is vital to performing the function of the NET Control Station and is very helpful to participating stations, especially when the participating station is inexperienced with the NET or NET operation. Check the Resources menu above to see if the NET Control Station Script is available for the ARES NET that you are interested in participating in.