[EAS] FCC reminder about Accessible Emergency Alerts

[Sean Donelan]

The FCC issued a Public Notice reminding video providers to issue 
accessible emergency alerts.  However, the issue is not limited to video 
providers.

https://www.fcc.gov/document/fcc-reminds-video-providers-issue-accessible-emergency-alerts

Although framed as an accessibility issue, there are several problems that 
radio, tv and cable systems regularly have with EAS messages.

1. Timing issues- Cutting off the beginning or ending EAS data bursts. 
With all-digital studios, radio and TV broadcasters no longer have the EAS 
equipment in-line.  Instead, digital switches are used. The switching 
isn't instaneous, and EAS equipment may need a 1 to 3 second delay to 
prevent cutting off the starting or ending data bursts.

2. Ducking and multi-channel audio.  The EAS message must replace *ALL* 
audio channels, not just duck the program audio. Sometimes with 5.1 audio, 
the EAS message is heard only on the center or left/right channels while 
the original program audio continues on the other 5.1 audio channels.  Or 
EAS replaces only the stereo mix but not the 5.1 mix.

Ideally, the digital mux has an emergency audio input which will replace 
the 5.1/stereo program audio with the mono emergency message and set the 
correct  audio transport bits.

For radio, make sure the EAS message is on both the left and right stereo 
or mono channels.  I've heard some radio stations with EAS on the left 
channel and program audio on the right channel at the same time.

Cable is more complicated, but same idea.

3. Video text crawls or slides. The entire text message must be visible
from the beginning to the end at least once.  Ensure the video crawl 
doesn't terminate early for short audio messages. Choose fonts, colors and 
crawl speed which are readable.

Because this National Periodic Test won't use IPAWS, only the default FCC 
header text will be available.