TYPES OF NETS

There are two types of R/T nets: directed and free. The type of net to be used is determined by the

operational situation. Regardless of the type of net used, a Net Control Station (NECOS) is assigned to monitor the circuit or circuits and enforce circuit discipline.

NECOS is the senior net member or designated authority. The NECOS is responsible for implementing operational procedures and enforcing discipline and security on the net. Enforcement of circuit discipline, however, is not the only reason for having a NECOS. Sometimes there are so many stations sharing a common circuit that a NECOS is necessary to facilitate the handling and passing of R/T traffic.

Directed Net

On a directed net, stations must obtain permission from the NECOS before communicating with other stations on the net. The exception to this rule is when a station has FLASH traffic to send. Also, transmissions on the directed net may be accomplished with a predetermined schedule.

Free Net

On the free net, member stations don't need NECOS permission to transmit. Net members must ensure that the net is not in use before initiating a call-up. A free net, however, does not relieve the NECOS of the responsibility for enforcing operational procedures and maintaining proper circuit discipline.

Both free and directed nets normally use collective call signs. Figure 2-1 diagrams an R/T net that consists of the following stations: USS Key, USS Mariano G. Vallejo, USS James K. Polk, USS Kamehameha, and USS Tecumseh. In this example, we will assume that the NECOS is Key. Notice that the collective call sign for the entire net is Poseidon.

Figure 2-1.-Radiotelephone net.

OPENING THE NET

The responsibility for opening the net for the first time or reopening the net after it has been temporarily secured belongs to Key. To accomplish this on a free net, Key would transmit:

"Poseidon, THIS IS Key, OVER."

After the transmission, all stations answer in alphabetical order:

"Key, THIS IS Kamehameha, OVER,"

"Key, THIS IS Polk, OVER," (and so on until all stations have responded).

After all stations on the net have answered, Key then sends:

"Poseidon, THIS IS Key, OUT."

This last message from Key informs all stations that their transmissions were heard and there is no traffic for them at the time.

If a station does not reply to the collective call within 5 seconds, the next station answers in proper sequence. Barring any difficulties the station may have, the delinquent station answers last. If the delinquent station is having difficulty that prevents an answer to the call, it reports in to the net as soon as possible with the transmission:

"Key, THIS IS (name of station).

Reporting In To Net, OVER."

At this time on the free net, and following a preliminary call, the stations concerned would start transmitting traffic to each other. For example, if Vallejo has traffic for Kamehameha, it would let Kamehameha know this with the call:

"Kamehameha, THIS IS Vallejo, OVER."

Kamehameha would acknowledge with:

"Vallejo, THIS IS Kamehameha, OVER."

Vallejo would then send its traffic.

On the directed net, when all communications over the net are controlled by the NECOS, Key would call the member stations and announce that the net is directed. In this initial transmission, Key would request information on the status of any outstanding messages. For example:

"Poseidon, THIS IS Key, This Is A Directed Net, Of What Precedence And For Whom Are Your Messages, OVER." Each subordinate station then answers in alphabetical order, indicating its traffic on hand. For example:

"Key, THIS IS Polk, I Have One IMMEDIATE And One PRIORITY For You, OVER."

"Key, THIS IS Vallejo, No Traffic, OVER." (Other stations respond.)

After all stations have checked into the net, Key would ROGER for the transmissions and commence to clear traffic in the order of priority. For example:

"Poseidon, THIS IS Key, ROGER, Polk Send Your IMMEDIATE, OVER."

After Polk has sent its transmission and obtained a receipt, net control then gives permission to transmit to the station with the next higher precedence traffic.

After the initial traffic is cleared, stations having messages to transmit to other stations on the net must first obtain permission from net control. For example:

"Key, THIS IS Tecumseh, I Have One ROUTINE For Polk, OVER."

Net control then answers:

"THIS IS Key, Send Your Message, OVER."

As you can see from our examples, circuit discipline is essential. Regardless of whether a single ship is entering port or several ships are engaged in a major fleet exercise, voice communications are required. The number of necessary circuits and nets increases with the complexity of the task and the number of units participating.

Whether the net is free or directed, the Net Control Station has the primary responsibility for expediting message traffic. Each station is responsible for assisting net control in the proper passing of traffic. Adherence to proper operating procedures and communications standards is essential in keeping a net free of backlogs and tie-ups.