In a state-wide communications emergency, there many kinds of messages will might need to be handled. These messages (tactical messages, manpower requests, welfare inquiries, medical information, casualty lists, requests for supplies, shelter resident lists, etc) will need to be carried on the most appropriate communication mode(s) that will best address the needs of our served agencies (packet or other digital modes, FM phone, CW, HF SSB, etc.).
The table below shows the most common types of messages expected in a state-wide activation of the Georgia ARES and the most appropriate communications modes to use to relay and deliver them.
| Message Type | Appropriate Communications Modes |
| Tactical Messages | The most likely kind of message that will be needed to be handled. Tactical messages may be local (related to incident command) or may need to be exchanged between a remote EMA office and the GEMA SOC in Atlanta; these messages must be accurately transmitted. Because Georgia is so large propagation paths for the various modes become an issue. The following modes, in priority/preference order have been tested:q Most appropriate mode for local tactical messages is FM phone (VHF)q Second most appropriate mode is FM phone via linked-repeater network; note that this has some advantages of FM phone (most esp. quieting), but some of the disadvantages of HF SSB propagation (noise on the channel, introduced by various links and controllers; multiple courtesy tones; dropped links)q For intra-state traffic of this type, HF SSB is currently the most used. For most traffic it is appropriate, however, at times, specifically during the day, the communications channels suffer from poor propagation pathsq Experiments show that there are times that a CW mode can successfully transfer the information when the phone modes cannotq The Signal-to-Noise requirements of PSK31 are so much better than other modes that it may be an effective mode, especially when all the others fail |
| Manpower Requests | Second most likely kind of message to be expected. These usually come in the form of tactical messages; as such, the tactical discussion above applies. For more complex requests, packet radio modes (APRS is most common of the packet modes in Georgia) is most appropriate. PSK31 should be considered a fall-back mode when other digital modes cannot propagate messages between southeast and northwest. |
| Welfare Inquiries | Best handled by store-and-forward modes; most requests come early in a disaster, but Red Cross et al do not take H/W for 36 hours after a disaster. Note that NTS is one form of store-and-forward mode; when relay operators are available, this can effectively handle this kind of traffic. However, precision IS important, since a H/W inquiry is usually directed at a particular individual; mistaken identity can create serious problems under many circumstances (at least, it can cause unnecessary worry for the people involved). |
| Medical Information | Rarely handled; best left to a secure mode. Red Cross & by GEMA have asked at times for totally secure communications, but Part 97 rules do not allow this. Digital modes (including Digital Voice, as in Alinco VHF radios) while not completely secure may be helpful modes for secure traffic. |
| Casualty Lists | Rarely handled; best left to a secure mode. Red Cross & by GEMA have asked at times for totally secure communications, but Part 97 rules do not allow this. Digital modes (including Digital Voice, as in Alinco VHF radios) while not completely secure may be helpful modes for secure traffic. |
| Requests for Supplies | Best handled by one of the digital modes, because of the complexity and need for precision; priority and urgency may dictate that some requests fall into the category of tactical messages |
| Shelter Resident Lists | same discussion as medial and casualty lists; these require secure channels |
| Disaster Assessments | Typically these are very much like tactical messages; best handled by FM phone, due to portability; GPRS-tracked APRS stations can also be very effective in assisting with these assessments. |
Table 4. Message Types and Appropriate Communications Modes in Georgia
HF Phone Communications
The primary communications mode for statewide communications in Georgia is 75-meter SSB phone (40-meter SSB phone as an alternate depending on propagation). The primary operating frequency on 75-meters is 3975KHz and on 40-meters it is 7275KHz. Should a communications emergency exist requiring statewide activation of the Georgia Section ARES, the Section Manger and Section Emergency Coordinator will work with the appropriate ARRL Headquarters officials to request a clear frequency, +/- 3KHz for statewide operations.
The SEC or appropriate DEC will call the Section Emergency Net to order.
Members of Georgia Section ARES are to check into the net from their mobile or home stations and then move to an assigned staging area to await further instructions by net control. Mobiles are dispatched as needed by the net control. Those operators with pre-assigned duties or locations may report there prior to checking into the state net. When not assigned to an operating location, ARES members should (silently) monitor the net frequency.
Liaison stations to the National Traffic System, Hurricane Watch Net, or other nets may be assigned if needed by the SEC and or ARES Net Manager.
Operators of home stations or amateurs that cannot drive may check-in and be given assignments aligned with their ability and situations. If possible, they will be picked up for service. Operators of home stations not on emergency power are coordinated to effectively maintain relief or other duties as the emergency moves past the "first alert" (first 72 hours) time. Please check-in however you can and declare if you will be available to help or know of a need.
Linked Repeater Net Operations
A system of linked 2-meter FM repeaters (linked using 440MHz links) has been established covering a large portion of the state, primarily in the Central and Northern areas. This system is widely used by the Skywarn program to support the National Weather Service by relaying observed severe weather reports and disseminating severe weather warnings.
This system could be used as an alternative to HF Phone communications, especially when unfavorable HF propagation exists. However, the needs of the NWS Skywarn program should not be impacted except in very extreme situations, as this is a critical communications function for NWS (public warnings are very often issued based on Skywarn operator reports).
Packet Radio Operations
Georgia has a unique geological situation, in that the north and west of the state are physically separated from the south and east. A "fall-line" where the mountainous north and west drops off to the flat coastal plain effectively cuts the state in two. There is very little digital communication across the fall-line. Hence, manpower requests or other requirements for digital communication have a difficult time being transmitted from southeast to northwest. The most common situation that generates these kinds of requests is hurricane threatening Savannah and the GA coast, in the southeast. The GEMA State Operations Center (where most of the requests need to be communicated to) is in Atlanta, in the northwest.
A project is ongoing to establish a system of linked digipeaters from Macon to Savannah down the Interstate-16 corridor. It is hoped that this system will provide a vital communications link from the Southeast coast to the Central and Northern sections of the state, and especially to Atlanta.
The two primary digital communications systems are the SEDAN (Southeast Emergency Digital Association Network) and the APRS (Automated Position Reporting System). Both networks are currently under utilized, but should be considered as part of the overall Section Emergency Communications System.
PSK31
PSK31 is a communications mode that offers a new and higher level of performance in conversational communications (keyboard-to-keyboard) than is available via HF phone. Computer hardware and software is used to decode the signal using DSP, and often it is possible to receive a signal that is much weaker than could be copied in other modes (even CW). The data transfer rate is comparable to CW (Morse Code).
The key advantage of PSK31 is the ability of Digital Signal Processing software to discern a signal despite unfavorable signal to noise ratios. This could possible allow reliable HF communications, statewide, when phone propagation is unfavorable (such as during daytime hours).