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A comment on mmWave radar, you won't see it coming.

Re:mmWave radar, you won't see it coming by chrismorgan on Tuesday February 01, 2022 @11:01PM (#30173543)
A technical error in one of the diagrams: Hall effect sensors are not binary, but one-dimensional, and are used so; their output voltage is directly proportional to the magnetic field strength. As for PIR sensors, fundamentally they’re certainly not binary, but I have no idea if they perhaps expose only a binary signal. A better example of a binary sensor might be an on/off switch.
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Re:mmWave radar, you won't see it coming by hornej on Tuesday February 01, 2022 @11:07PM (#30173586)
thats a good point about the hall sensors. i'll update that. PIR sensors also output an analog signal, but in practice they are binary.
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Re:mmWave radar, you won't see it coming by relaxing on Wednesday February 02, 2022 @01:46PM (#30182007)
There’s a funny autocorrect typo in the Adams quote: Zaphod -> Zappos.
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Re:mmWave radar, you won't see it coming by hornej on Wednesday February 02, 2022 @03:15PM (#30183367)
lol, thanks. fixed it
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Re:mmWave radar, you won't see it coming by stingrae on Wednesday February 02, 2022 @01:20AM (#30174433)
in practice they don't have to be binary
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Re:mmWave radar, you won't see it coming by mycall on Tuesday February 01, 2022 @11:17PM (#30173646)
If you include time dimension, hall effect sensors are two dimensional.
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Re:mmWave radar, you won't see it coming by stingrae on Wednesday February 02, 2022 @12:23AM (#30174060)
analog PIR is typically a differential signal between two receivers. The receivers are placed behind a fresnel lens (where the lenses are designed to point into each of the sensors). So when an IR source (like a person) walks in front of the sensor it creates a large spike, because they are being compared against a low IR area.

There is a form of PIR sensing where it behaves like a thermal camera at a very low resolution (sometimes as low as 2x2 pixels)

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Re:mmWave radar, you won't see it coming by hornej on Tuesday February 01, 2022 @11:12PM (#30173630)
most hall effect sensor applications i've seen use a schmitt trigger and output a digital (on/off) signal
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Re:mmWave radar, you won't see it coming by choonway on Tuesday February 01, 2022 @11:24PM (#30173686)
the only true binary sensor i can think of are good old fashioned mechanical switches.
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Re:mmWave radar, you won't see it coming by samatman on Tuesday February 01, 2022 @11:38PM (#30173766)
Mercury switch on a bimetallic strip (old-school thermostat) counts, same basic principle.
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Re:mmWave radar, you won't see it coming by stingrae on Wednesday February 02, 2022 @01:21AM (#30174438)
reed switch
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Re:mmWave radar, you won't see it coming by relaxing on Wednesday February 02, 2022 @01:47PM (#30182034)
is an old fashioned mechanical switch.
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