EAS at the Edge℠ - What does that mean, and why should I care?

By Guest Author on May 23, 2024 2:49:19 PM

EAS alert distribution finally realizes the benefits of AoIP

Guest editorial by Bill Robertson, VP Business Development, Digital Alert Systems, Inc.

(At NAB Show 2024, Telos Alliance, Digital Alert Systems, and Nautel announced a joint technical collaboration designed not only to complete the all-AoIP air chain but to give broadcasters more control, reliability, and flexibility in EAS implementation. - Ed.)

U.S. Broadcasters are required to provide emergency alerts to their audiences, but many radio stations use IP-based signal distribution — something incompatible with old-style EAS boxes. What is needed is a simple way to interface the real-world over-the-air reception of EAS events, filter and process the messages, and — if necessary — incorporate the alerts into the modern audio-over-IP (AoIP) air chain.


The EAS at the Edge concept posits that any network has two edges — the input and the output. These are the real-world edges, with transducers linking the analog and digital worlds. Think of it like a microphone at the input and a speaker at the output. All kinds of things can happen between those two points, but you must be able to interface with the real world for it to be meaningful.

The FCC dictates the EAS input side, with a minimum requirement to monitor at least two over-the-air stations. These are your LP-1 and LP-2 sources. Your station must also monitor the FEMA IPAWS system over the Internet. While the radio inputs include audio, the IPAWS feed often does not, so we need the ability to create audio using a text-to-speech engine.

So, for EAS, we want to capture and process the alert messages at the input edge and, if the conditions warrant, send the signal directly to the output edge. Here, we place the Digital Alert Systems’ DASDEC™ to receive and decode alert messages, applying the station’s rules to determine if the alert should be forwarded.

And if so, here’s where the magic happens.

EAS at the Edge - Figure 10

Converting an audio signal to a streaming IP format like AES-67 is not difficult; however, ensuring the EAS-carrying signal is correctly routed through an IP air chain is — and this is critical! Traditional EAS devices are placed at the end of the signal path so that no other device can interrupt the interruption. We must ensure that the EAS signal will make it to the output when required.

This is why simply converting EAS audio to AoIP alone is not enough. We must include very specific routing information so that the IP air chain guarantees the EAS signal makes it to the output. This is why the DASDEC incorporates the LiveWire+ routing protocol so the combined solution performs both tasks.

EAS at the Edge - Figure 8

Using Telos Alliance's LiveWire+ AoIP protocol and Axia Pathfinder Core PRO broadcast controller, we force downstream devices to change the signal path, ensuring the critical EAS message audio is routed to the output. But triggering the path change once is not enough. We must continually monitor the signal path to ensure that nothing else — human or automation — changes the signal routing until the EAS event concludes. This signal path management logic forms a critical link between the DASDEC at the input and the device at the output.

The brilliant part of this solution is that the output edge can go all the way to the very end — right to the transmitter. For example, the Nautel GV series features an integrated LiveWire+ compatible "Omnia For Nautel" audio processor, which means DASDEC communicates directly to the last device in the air chain — the transmitter. Input edge to the output edge, all over IP.

EAS at the Edge - Figure 9C

Why is this important to me?

Simplification. The DASDEC is an FCC-certified receiver / encoder / decoder integrated into one box, performing RF demodulation, FSK data decoding, TTS generation, and data filtering/preprocessing. Given these regulatory and operational realities, the DASDEC serves as a versatile edge device — an entry and exit point to the broadcast system and the interface between the virtual environment and the real world. Linking the information directly to the transmitter eliminates a host of other devices or operations seen in a typical air chain. HD radio can achieve further simplification by simultaneously synchronizing all the outputs without requiring separate exporters.

Efficiency. By processing data at the edge, only relevant alert data is sent through the network. This reduces the amount of data that needs to be transmitted, minimizing the amount of traffic and conserving overall data bandwidth. 

Reliability. The DASDEC will continue to function and perform critical monitoring and message-decoding tasks even when the network is unreliable or temporarily unavailable. Moreover, if the network “edges” are collocated in the same local LAN, the entire process can continue to work regardless of broader network access.

Regulatory Compliant. The DASDEC meets all the necessary regulatory standards, government approvals, and certifications, operating within the current guidelines and FCC rules. We don’t have to petition the FCC for changes — something that could result in further constraints and potentially unwanted ramifications.

Audience Engagement. Adding EAS-Net™ — Digital Alert Systems’ advanced communication protocol — allows compatible downstream equipment to provide more details to the audience. This is done in the form of an alert text using RDS and even by replacing the album art with sanctioned icons that represent the context of the alert. Now, audiences can quickly see what the alert is about, and we can keep these elements on their screen for the duration of the alert.  So, even if they tuned in after the original alert aired, audiences can immediately recognize that there is an ongoing or potential threat.


EAS at the Edge is a giant leap forward in bringing the critical function of EAS into the modern radio station. With simplicity, reliability, and better audience engagement, it combines technical prowess and station compliance in one winning platform.

Topics: IP Studios, virtualization

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