National EAS Test

FM does it with frequency!
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Re: National EAS Test

Post by jthorusen » Sat Aug 10, 2019 7:37 pm

RodeoJack's comments have a lot of validity, it seems to me. However, since I am taking care of a low power FM station, the issue does not arise. All of our audio processing is done in the station automation computer. From there, an analog audio output (Left and Right) goes to the EAS decoder, then to an audio DA and then to the two low power transmitters (Main and Aux). The transmitters have stereo generators built into their exciters, with all processing turned off. So, what the EAS box gets is what we send... within the limits of the state of the art, of course.

For stations with Optimods or similar equipment, it seems to me that it would make sense to have the audio buss broken out after the processing but before the stereo generator and insert the EAS box there. I don't know if the audio processor manufacturers do this or not, but perhaps they ought to, or perhaps the units could be modified.... assuming the whole process isn't done in one giant digital number manipulation.

Alternatively, the EAS box manufacturers should be encouraged (mandated?) to handle composite stereo instead of discrete analog audio. When an alert is received, the composite stream would be interrupted and a simple L+R (mono) signal sent on to the exciter(s). No processing = minimal distortion.

AM stations would, of course, have to be handled somewhat differently, but the general idea would be the same.

Obviously, the system as implemented today is the next thing to useless.
James K. (Jim) Thorusen
Central Coast Electronics
NW Oregon Consulting Bdcst Eng.

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Deep Thought
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Re: National EAS Test

Post by Deep Thought » Sat Aug 10, 2019 11:10 pm

Part of the problem here is that the system is designed to be a "scorched earth last resort" relay which doesn't rely on external infrastructure to get the word out. This is a noble goal, but unfortunately broadcasting is an ignoble business. If stations truly operated in the public interest they'd spend the buck fifty to make sure this worked right.

Overall, this is just one more sad example of why the entire industry is becoming more and more irrelevant.
Mark Mueller • Mueller Broadcast Design • La Grange, IL •

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