Show HN: Formally verified FPGA watchdog for AM broadcast in unmanned tunnels

Re:Show HN: Formally verified FPGA watchdog for AM broadcast... by mech422 on Wednesday February 18, 2026 @04:32PM (#47066740)

I must be missing something ... Why broadcast speech over AM in an 'unmanned' tunnel ?? who's gonna hear/receive it ?? I wish the repo had some sort of use case summary or something...

Edit: I'm also sorta puzzled by the choice of AM in any sort of 'alert' context...Do people still listen to/use AM radios?

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Re:Show HN: Formally verified FPGA watchdog for AM broadcast... by jacquesm on Wednesday February 18, 2026 @05:01PM (#47067046)

AM radios are extremely simple and utterly fool proof, they can be made with only a handful of simple parts. Even so, these systems are archaic and these days you can make much more complex radio systems using a SDR which effectively reduces the whole radio to a pre-amp an ADC, an embedded CPU and some software.

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Re:Show HN: Formally verified FPGA watchdog for AM broadcast... by drweevil on Wednesday February 18, 2026 @06:41PM (#47067964)

AM is a good modulation choice for low signal environments. It is used in the airbands for this reason.

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Re:Show HN: Formally verified FPGA watchdog for AM broadcast... by jacquesm on Wednesday February 18, 2026 @06:48PM (#47068017)

Precisely, it degrades very gracefully, unlike FM or digital.

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Re:Show HN: Formally verified FPGA watchdog for AM broadcast... by anonymoosestdnt on Thursday February 19, 2026 @02:55AM (#47071099)

Updated the README with a use case section - vehicles with AM radios transit during construction/maintenance. Leaky feeder distributes the signal. Thanks for the feedback :)

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