Most Popular Articles
Public Safety and Radio Broadcasting
The use of radio stations to disseminate information to the general public can be traced back to 1951 when Conelrad (CONtrol of ELectronic RADiation) was implemented. The theory behind the system was pretty simple: Once activated, all stations were to shut down, except certain designated stations (one from each region), that would broadcast on either 640kHz or 1240kHz. The reason for this was to effectively jam the radio direction finders (RDF) of an attacking air force thus preventing it from locking on specific targets. Citizens knew where to tune their radios during such an activation by the triangles printed on the tuning dials.
In 1964, Conelrad was replaced by the Emergency Broadcast System (EBS). At the height of the Cold War, this method, formerly focused on providing mass notifications of national events, such a nuclear attacks, evolved into a means of providing alerts at the state and local levels. State-level plans were put into place, and unlike Conelrad, stations (now including FM and TV) were allowed to voluntarily participate in the alerting. This was good for a participating station because they would not be required to sign off and they could keep listeners (or viewers) tuned in. Of course if a station did not elect to participate, it would still be required to turn off.
By 1972, state plans were in place, which permitted not only state, but local agencies to activate the system. This marked the beginning of the meaningful relationship between public safety agencies and broadcasters.
In 1994, the FCC established the EAS (Emergency Alerting System), which utilizes a digital architecture that permits it to operate reliably in unmanned operations, such as cable head-ends. The system is based on the same protocol used by the National Weather Service (NWS).
In May 2007, the Commission adopted a Second Report and Order in which it provided the groundwork for “Next Generation EAS” with four cornerstones:
■ Maintain the existing EAS network;
■ Utilize a common messaging protocol, the Common Alerting Protocol (CAP), to be implemented by all EAS participants following its adoption by FEMA;
■ Incorporate new authentication and security requirements; and
■ Foster the deployment of new, redundant EAS delivery systems, including satellite, Internet, and wire line networks. These new networks should support delivery of more targeted and detailed alert information to EAS Participants based on CAP to be developed by FEMA.
FEMA officially adopted the CAP version 1.2 on Sept. 30, 2010. According to FEMA the major advantages of CAP are:
CAP alerts are transmitted in digital format; therefore, there is no degradation of quality of the content that may be experienced with analog methods such as radio.
CAP alerts can be directly available to encoder/decoder equipment within seconds of their creation; therefore, delays or disruptions relating to station-to-station, over-the-air relay are reduced.
The Internet infrastructure has a high level of redundancy and reliability, and may survive when other channels of communication do not.
In addition to EAS-required data, CAP alerts may carry rich information such as audio, video, geographical-location data, etc., that EAS participants may opt to use for supplemental information to provide to their audiences.
- continued page 2
Acceptable Use Policy blog comments powered by Disqus
[an error occurred while processing this directive]
Today in Radio History
The history of radio broadcasting extends beyond the work of a few famous inventors.
Read each issue online in our Digital Edition Format in your Web browser.
EAS Information More on EAS
The feed provides feeds for all US states and territories.
Need a calendar for your computer desktop? Use one of ours.
Information from manufacturers and associations about industry news, products, technology and business announcements.
Browse Back Issues[an error occurred while processing this directive]
Also in the November Issue
- Trends in Technology: HD Radio Transmission Update
- Franken FM Stations
- Wi-Fi on Wheels: The Connected Car
- Field Report: Yamaha MG10XU
- Transmitter Site Cleanup