In the aftermath of January's devastating earthquake in Haiti, rapid communication was critical to the rescue and aid efforts. One of the key links in the response was an obscure radio network designed to carry messages when traditional communications infrastructure has been wiped out.
The National Public Health Radio Network (NPHRN) was activated during the earthquake to provide vital communications between the Centers for Disease Control and Prevention (CDC), the Federal Emergency Management Agency (FEMA), Federal Communications Commission-licensed communications services and other agencies in the affected areas in Haiti.
The NPHRN, a unit of CDC Coordinating Center for Health Information and Service, is designed to be used during such events, when traditional communications, such as the telephone, the Internet and cellular networks are damaged or overloaded.
"The purpose of the [network] is to provide the CDC and state, territorial, tribal and local health departments with a non-infrastructure dependent communications capability to ensure the exchange of critical health-related information under all conditions," said David Clark, the CDC's NPHRN manager.
The radio network was created in 2003 with the assistance of FEMA, which controls the 14 frequencies maintained by the CDC. After the terrorist attacks of Sept. 11, 2001, when getting public health information to New York City was difficult, CDC began exploring the use of the frequencies for health messaging, Clark said.
The NPHRN is a stand-alone network, separate from any other networks, much like those operated by FEMA and the U.S. Department of Homeland Security. As such, it operates separately from the Internet. And it would continue to function even if the Internet or public-switched telephone network were to go down (as it did in some areas during Hurricane Katrina, in 2005.)
The network uses HF radios that meet federal and military standards for operation on frequencies in the Automatic Link Establishment (ALE) mode. "ALE technology allows the radio to select the appropriate frequency and establish communications links with other NPHRN stations without the use of highly-technical operators," Clark said.
The NPHRN is based in Atlanta at the CDC's Emergency Operations Center (EOC). There are only six CDC employees that know how to operate its high-frequency (HF) radios, Clark says. CDC has a yearly contract with a company that provides technical support and runs the weekly activating exercises the center conducts with the state and local health departments on the network, he says.
The network operates in conformance with the National Response Framework, which establishes a comprehensive, national, all-hazards approach to domestic incident response.
"HF radios in the network are normally left in the "˜scan' mode, so that they are scanning through their assigned frequencies and listening for a call addressed to them," Clark said. "When such a call is received, the radio sounds an alert and the operator then picks up the microphone and responds. Any station can initiate this call."
City and county health departments can use the network to communicate with their state health department if other means of communication are interrupted. State, territory and tribal health departments would then be able to communicate directly with the CDC. Local public safety organizations could use the network to communicate with their headquarters in accordance with state or local plans.
The back-up communications system uses specific radio frequencies within the high-frequency radio spectrum. CDC provides financial assistance to states to acquire the required radio equipment through grants. There are about 20 state health departments and more than 10 local health departments that have the capability to transmit information across the NPHRN, said Clark.
Clark says the CDC would like to see the NPHRN expanded to include all states, territories, tribal and major city and county health departments. And there are other plans in the works to increase the network's functionality.
"We are looking into the possibility of adding a data capability to the network to ensure that highly technical information and terms are not misunderstood during transmission," Clark said. To support data transmission, the CDC is considering using data modems standardized by the Department of Defense for use with HF radio systems.
The center is also looking into ways to protect the information that is transmitted over the network from interception and misuse. One possible solution is encryption devices, Clark said. But a final decision on which devices and levels of encryption are needed hasn't been made, he said.
