system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does the severe weather alert system that broadcasts over your television sound like I'm logging on to the internet in the 90's?

We are having severe weather here and they just did a test over the tele and it got me wondering.
gpt
It's actually quite intentional.

The Emergency Alert System is designed to be broadcast in case of any emergency, whether it's a weather alert or a Presidential Alert. The system doesn't differentiate where the signal is sent, and is broadcast nationally for each alert, but you don't see the ones that don't apply to you because of those tones at the beginning of the broadcast.

The first time the modem noise is played, the EAS is broadcasting information about the affected area, the type of alert, and the originator to the EAS device located at the station. This code is then repeated two additional times in order to ensure that the data was correctly interpreted on the receiving end. The receiver at the broadcast station reads this data, determines automatically if the alert is valid for the broadcast area, and cuts into whatever is playing in order to relay the information.

This is the same principal as the handshake your modem used to connect to the internet, but with different data since certain things are assumed (Baud rate, transmission format, frequency, etc.)

The three tones at the end of the EAS broadcast are the "End of Message" tones.

TL;dr: It's because the alerts are sent by a system that's pretty close to a modem.

(edit: Moved a few letters around for clarity's sake.)