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.

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 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:

• Establishing a centralized NET to coordinate, organize and execute deployment of Amateur Radio operators.

• Planning for fixed position staffing of Amateur Radio personnel:

  • Qualified staffing of hospital positions to augment overloaded communications infrastructure or replace failed communications infrastructure.

  • Qualified staffing of Red Cross evacuation centers.

  • Qualified staffing of EOCs.

  • Staffing of any location / position at the request of incident commanders. This may require NET control operators to provide detailed directions to the incident command location.

• Emergency Coordinators should prepare a roster of Idaho ARES volunteer Amateur Radio operators that can be called up for service. All contact mechanisms to call up an Amateur Radio volunteer should be included in the roster.

• Ideally, all volunteers would already be members of Idaho ARES and would have completed the basic required training courses. However, in times of real emergency, untrained volunteers will appear and request that they be dispatched to a position. It is the NET control operator who must quickly determine if there is a need for such a resource, vet the resource to determine capabilities and competence, and either queue the resource or dispatch the resource as appropriate. A procedure should be in place to assist the NET control operators in the vetting process.

• If an equipment pool is available, the plan should include a process for tracking of equipment. Equipment should be tracked from stored inventory, check-out and return to stored inventory. The condition of equipment when removed or returned should be included in the inventory tracking.

• Planning should also provide for the establishing of secondary NETs. The scale of an event will largely determine if a secondary NET is required. Having a plan for secondary NETs will enable an orderly implementation. Secondary NETs may become necessary when the amount of traffic on the primary NET exceeds the bandwidth available to handle that traffic, or when the scope of the traffic becomes too broad to maintain control of the NET or to retain focus on the primary purpose of the NET. Secondary NETs may include:

  • An evacuation center NET to coordinate the logistics of dispatching supplies and staff.

  • A message passing NET to handle critical messages between served agencies where the bandwidth required to handle message traffic exceeds the capabilities of the primary NET.

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).

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

• Communicate clearly

• Make a rapid determination on how a request is to be handled

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.

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:

• Minimum bandwidth consumption, which leads to the ability of the NET to handle a higher number of traffic messages.

• Lossless communication of information, resulting in accurate conveying of information.

• Minimized latency for those stations needing to pass traffic after you.

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.

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.

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.

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:

• Directions to a disaster scene.

• Required prescription medications.

• A roster of evacuees.

• Bulletins

• Situation Reports

• Road Closures

• Contact Information

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

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.

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) 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.

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.

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.