Ask HN: How would French police locate suspects by tapping their devices?

Re:Ask HN: How would French police locate suspects by tappin... by dylan604 on Saturday November 04, 2023 @03:53PM (#38144524)

I don't even know what the "mic needs a clock" means. I've never used a microphone that needed a clock. Making a mic that needs a clock just seems like a "WTF were they thinking" kind of thing. Can you elaborate on this concept of requiring a clock for a mic?

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Re:Ask HN: How would French police locate suspects by tappin... by theamk on Saturday November 04, 2023 @06:13PM (#38145719)

The keyword to search for is "digital mems", and of course we are talking individual parts to place on PCB, not the consumer device. Here is one random example: [0]. Somewhat expensive at $1 ea, but that's what you pay for US manufacturer.

This microphones take 2.4 MHz clock and return PDM (pulse density modulation) signal. Does not seem very convinient for old-school analog electronic circuits, but it's pretty trivial to interface with any micro with pulse counter hardware.

And presumably the audio won't have any hum or interference from nearby radio transmitters, which is especially useful in cell phones.

[0] https://www.digikey.com/en/products/detail/cui-devices/CMM-4...

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