This is the third part of a series of articles about designing an NTS section net. In Part 1, we used the Buckeye Net Mission statement to lay out what the net must accomplish. In Part 2, we began looking at the foundational requirements and constraints to determine how the net must look. In this third part, we will expand on what was begun in part two. We will narrow down the operating frequencies we need for operation of the net. We will also look deeper into the structure of the Buckeye Net required to serve the net’s users.
We determined in part one of the series that the section net needs to serve the entire section. In the case of the Buckeye Net, we need to reach from any one place within the State of Ohio to any other one place within the State.
The State of Ohio is approximately 225 miles from the western edge to the eastern edge of the State. It is also approximately 225 miles from north to south. The longest distance within the State, from Conneaut in the northeast to Cincinnati in the southwest is a bit less than 300 miles. These distances are much longer than can be covered by a simplex VHF or UHF net, thus requiring the use of HF frequencies.
Fortunately, we can use Near Vertical Incidence Skywave (NVIS) propagation to reach all of the stations within the State. NVIS propagation is simply using typical HF ionospheric propagation characteristics in a way that emphasizes enhanced propagation within relatively short distances. Normally, amateur radio operators are interested in contacting stations at great distances from their own station. This kind of propagation requires launching our signal at a low angle so that when the F layer refracts it back toward earth, we’ve achieved maximum distance. We use a dipole at a high elevation or even a vertical antenna in order to keep a low angle of radiation. In order to achieve NVIS propagation, we can use a simple dipole antenna at a relatively low height. Old-timers may remember calling this type of antenna installation as a “cloud burner”. This is exactly the effect we need for NVIS operation. The relatively high angle of radiation refracts the transmitted signal back down within the “skip zone”, thus achieving NVIS propagation with solid signals out to 300 – 400 miles. A dipole placed between approximately 0.1 to 0.2 wavelengths high achieves this type of propagation.
Antenna height, however, is not the only consideration for achieving NVIS propagation. NVIS propagation is most pronounced at frequencies from 2 MHz through about 10 MHz. Transmit frequencies above 10 MHz tend to not be refracted back into the skip zone. As the transmit frequency increases above 10 MHz, the signal tends to pass through the ionosphere rather than refract back into the skip zone.
The ham bands that are likely to exhibit NVIS propagation are the amateur radio 160 meter, 80 meter, 75 meter, 60 meter, 40 meter, and, 30 meter bands. These are the bands of most use in carrying out NVIS communications within the Ohio section. These are the bands an NTS section net station should be able to use. Most section net activity will typically be on the 75/80 meter bands. The 160m, 60m, 40m, and 30m bands will be needed for use in specific conditions and/or situations.
The next question to address is to determine how many stations might need to check in to the section net. We determined earlier that the ideal net should have seven to ten stations in order to maintain reasonable efficiency. If the section were to experience an emergency covering the entire Ohio section, we would need, as a minimum, an NCS, ANCS, 8RN representative,and 88 county EOCs. If we add interoperability stations and some transient stations, we could easily exceed 100 stations in the network. Obviously, a single net is inadequate to handle such a number of stations.
The solution to this problem is to add sub-nets to the top-level section net. The Ohio Section ARES has divided the 88 counties of the section into ten ARES districts. As a first stab at organizing the section net, we could specify an NTS HF net to cover each district. Assuming one liaison representative for each district net, the section net would have an NCS, ANCS, 8RN rep, and ten district liaisons. The section net size would have 13 stations, minimum. If we add the state EOC, a rep for 60 meter interoperability, and several transient stations, the net far exceeds the desired size. Adding ten ARES district nets is a start, but, is not sufficient in the worst of cases.
In the state of Ohio, FEMA divides the state into five FEMA regions. We can also consider dividing the Ohio section into five NTS regions, Now, our top-level section net consists of an NCS, ANCS, 8RN rep, five NTS region reps, the state EOC, and a 60 meter interoperability rep. This sets the section top-level net at ten stations. This number is within a reasonable span-of-control and would allow for several transient stations without much problem.
This hierarchical network structure provides a template for the activation of the section net under any conditions while keeping the size of any individual net within a reasonable span-of-control. The section top-level net can be activated first. Additional sub-nets can be added or dropped as the situation warrants. Each sub-net will follow the basic NTS net structure, that is, net manager, NCS, ANCS, and liaison stations. This structure allows for maximum flexibility. Activation and deactivation of any particular sub-net, or group of sub-nets, can be determined by the needs dictated by the situation at any given time.
The ARES is set up to focus on serving the needs of a single county. The communication needs of the county are coordinated by the ARES county EC. We will assume that the individual county is the smallest unit that the section net will serve.
The smallest emergency would occur within a single county. The existing ARES VHF/UHF net would likely be all that is needed to handle the communication needs and the section net would not need to be activated. Should the need arise for the county to communicate with the state EOC, an HF-equipped local station could make the needed link directly with the state EOC.
The need for the Buckeye Net would occur if the emergency included an area that was too large to be reached by local VHF/UHF nets. Perhaps a winter weather system is coming down affecting the northeast corner of the state. Knowing that the emergency will progress slowly, from northeast to southwest, the Buckeye Net could be brought up in stages. The first level of activation would be the section level net. The section level net would consist of the section NCS and section ANCS. Knowing that the weather will eventually cover the entire state, the state EOC joins the section net. Each affected county will join the section net as the weather system arrives and communication with each other and with the state EOC is needed.
At some point, the net will have six or seven counties joined in and the net would have ten stations or so. We can reasonably expect this number to rapidly increase becoming too many stations for maximum operating efficiency. The northeast corner of the section is covered by ARES Districts 5 and 10. A net covering each of these districts can be activated relieving the load on the section net. In this case, we would have an ARES D5 HF net and an ARES D10 HF net. Each of these district nets would send representatives to the section net to relay traffic going outside the district and to pick up traffic destined for the district net. Additional counties outside of D5 and D10 would continue checking in to the section net.
As the storm advances, counties from ARES districts 1, 6, 7, and 9 start joining the section net. Those district nets activate their respective district HF nets. Adding four more liason stations would start to overload the net. Anticipating this need, The necessary NTS region nets would be activated and send their representatives to the section net. Existing district liaisons and county liaisons would be excused from the section top-level net and report in to their district or regional nets.
The ability to add and drop sub-nets makes the Buckeye Net both flexible and scalable. Sub-nets can be added in any order and in any number depending on the current needs. Should some unanticipated net show up, they can be coordinated by the top-level net and assigned to the section, region, or district level as is most appropriate for their purpose.
The state EOC and 60m rep stations are shown only on the top-level section net. This arrangement makes any 60m interoperability net (OHMR, FEMA, etc.) and the state EOC easily available at all times to all stations. Should any station at any level have emergency traffic, they can bring it immediately to the top-level net. Routine and priority traffic can be routed through the appropriate net liaison stations. The top-level section net is the first one activated and the last to be de-activated. This makes the 8RN, 60m rep, and state EOC immediately available for the entire section throughout the entire emergency.
We have further refined the frequency needs of the Buckeye Net in order to serve the needs of the entire section. We have taken a deeper look into the structural requirements for the Buckeye Net in this article. We developed a hierarchical structure to serve as a template for activating the network in an emergency. We examined the flexibility and scalability issues and have presented a proposed solution to meet these requirements.
In the next, and final, part of this series, we will put all the things we looked at in this and the previous articles into a more definite structure and add some final touches in describing the Buckeye Net. Finally, we will discuss some ideas for developing the training needs and non-emergency Buckeye Net structure and operation.