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by tekromancr 1634 days ago
We do have real life targeted ads. The NYC Link terminals, for example, can detect tons of data about the devices people carry, and the comings and goings of the owners, and sometimes link them to their ad profiles. ads for display can then be selected accordingly.

This isn't even particularly new tech, they prototyped roadside billboards thay could infer what radio stations the cars driving by were listening to, and this was in the early 2000s
1 comments
aesthesia 1634 days ago
> they prototyped roadside billboards thay could infer what radio stations the cars driving by were listening to

Any idea how this was supposed to work? I don't know how that information would leak out unless it was just listening for the audio from a car with windows rolled down.

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banana_giraffe 1634 days ago
An archive of the company behind that tech [1], has this to say:

> Each car radio sends out a signal at a frequency higher than the one it is receiving from the radio station. When a car passes by one of the MobilTrak sensors, the sensor picks up on the signal to determine what the driver is listening to on the radio

And US6813475B1 seems to be the patent behind the tech.

If they ever really could find that sort of signal in the noise of the real world, I've got to imagine that improved tech for in-car radios, not to mention people listening to their phones via Bluetooth and SiriusXM, has rendered it even more broken.

[1] https://web.archive.org/web/20020720075012/http://www.mobilt...

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matheusmoreira 1634 days ago
> Each car radio sends out a signal at a frequency higher than the one it is receiving from the radio station.

Why would it do that? I thought car radios were merely receivers, not transmitters. This is insane...

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xyzzyz 1634 days ago
It is a result of the mechanism used for operation. See https://en.m.wikipedia.org/wiki/Superheterodyne_receiver especially the section on Local oscillator radiation
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dmm10 1632 days ago
Most radio receivers transmit a very weak signal slightly higher than the carrier frequency of the station tuned as a result of how they enhance received signals. Look up superheterodyne for details.
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gruturo 1633 days ago
It's a side effect of how tuning works (local oscillator), and the signal is extremely weak, very little of it radiates out due to some components / PCB traces behaving as an accidental (poor) antenna.

Still, with good enough equipment it can be detected even from some distance.

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heavyset_go 1634 days ago
Check this out: https://scholarsmine.mst.edu/cgi/viewcontent.cgi?referer=&ht...
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