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​​​​Warning and Communications Systems 

The Pennsylvania Emergency Management Agency (PEMA) propelled Pennsylvania into a national leadership role in the advancement of the Emergency Alert System (EAS) by deploying a satellite-based “EMnet EAS System” to county, television, and radio stations with an FCC "city-of-license" located in the Commonwealth of Pennsylvania.

Effective March 2003, PEMA’s Emergency Management Network (EMnet) became the primary delivery path for EAS distribution in Pennsylvania.

The secondary EAS source path utilizes the fiber optic backbone of the Pennsylvania Public Television Network direct to regional LP-1/LP-2 affiliate facilities-who then relay the backup EAS network to applicable areas.

PEMA Emergency Management Network Goals

EMnet currently has 362 terminals throughout the commonwealth and is growing every day. PEMA continually strives to keep our communities safe, and EMnet helps the agency achieve this goal. Emergency situations occur each and every day and may require emergency management agency (EMA) and 911 staff to inform the public and issue instructions for their protection and safety.

The primary goal of EMnet is to ensure the safety of our communities during emergencies and disasters. The intention of purchasing this system for emergency alert activations was to specifically meet the needs of a growing emergency management community. Our communities rely on EMAs and 911 centers to get the word out in the event of an emergency.

PEMA specifically requested a system that we could send messages to individual stations, groups, or all terminals and to have this system provide the agency with confirmation of delivery. This network has taken us to the next level away from the “Daisy Chain” style system.

EMnet is designed to meet what EMAs and 911 centers need most: a system that is fast, secure, and reliable. It provides the ability to communicate during emergencies where emergency activations are necessary.

What is the difference between an EMnet and EAS Message?

An EMnet message is a text-based message. These messages may include attachments and are sent from other EMnet stations, which resemble email, and are the dominant form of communication on EMnet System among users. These are also the type of messages that are utilized for passing important information to broadcast media news centers.

An EAS message is a text and audio message that is intended for rebroadcast to the public. The intention of the EAS is to distribute warnings to the general public. EAS activations are authorized when a “loss of life” or “loss of property” has occurred or is anticipated. The required threshold of either “an EAS-Short-Fused Response Requirement” or “An Emergency Event Affecting a Wide Area” has been met.

The National Weather Service (NWS) or other government agencies can generate these messages.

EMnet has a platform that allows EAS messages to be originated, transmitted, and broadcast; however, it should be noted that the two message types are different and can be of different origins.

How does EMnet improve EAS?

EAS messages are far too often conveyed verbally before being recorded for broadcast relay to another station, which may, after capturing the message, relay it again to yet another station. This process takes valuable time, which may again be delayed by volunteer broadcasters that may not rebroadcast the message immediately, or at all.

There also is a loss of message clarity as it is recorded and relayed. There is no confirmation that the message was delivered and received by the next level in this "daisy chain" style system. Compounding this process, the majority of the encoder-decoders used by broadcasters are not easily upgraded to meet ever-changing needs, including the addition of new codes to support such programs as Amber Alert.

Further, EAS is audible only. It does not allow for the distribution of pictures that might accompany an Amber Alert, or even the URL of where to go to get such information. EMnet allows for:

  • Direct-to-broadcaster transmission
  • Forwarding of pictures, attachments, reports, and other data
  • Confirmation that the message was delivered to specific radio stations
  • Confirmation that the party in question broadcast the EAS message
  • Transmission of messages in languages other than English, to better serve citizens using Spanish, French, and other language radio and television stations

Terminals and Connectivity

EMnet currently has 362 terminals throughout the commonwealth:

  • 214 are broadcast stations
  • 62 are cable networks

PEMA also has the capability of monitoring the entire network to ensure 100 percent connectivity. Immediate attention to alert a station is provided in the event an EMnet terminal is offline and to provide trouble shooting and fault isolation. PEMA strives to improve our EMA's and 9-1-1 centers working relationship with broadcast stations, as well as the cable networks.


In its role as Pennsylvania's primary warning point, PEMA requires robust communications facilities to contact county and city government, its regional offices, and other commonwealth agencies.

The Satellite Emergency Voice Alerting Network (SEVAN) and PaSTAR, its innovative, satellite-based data network, are part of the overall complement of tools the agency uses for warning and communications functions.


The voice "side" of the satellite warning system allows PEMA, counties, regional offices and cities to communicate directly in real time regardless of the status of telephone systems. Warning messages are routinely broadcast by PEMA using this system. It is based on one of the constellation of statellites in geosynchronous Earth orbit and is online and available continously.


In its simplest form, PaSTAR -- the Pennsylvania Statewide Telecommunications and Alerting System -- is a computer network without wires. Using satellite-based technology and the latest computer server and client systems, the system allows data-sharing, reporting and textual and graphics communications to flow unimpaired between users connected to the system. At the core of PaSTAR are commercially-available computer server and email software packages widely used in internet communications.

For technical information on SEVAN or PaSTAR, contact Technical Services at 717-651-2727. Operational information is available by contacting PEMA Operations at 717-651-2001.