Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

mmWave radar, you won't see it coming

joshhorne.com

Post reply on HN
Print view View original

41–50 of 192 posts

Re: mmWave radar, you won't see it coming

#41

Post by colechristensen »

leohonexus wrote: post #33

Very dumb question: If mmWave is operating at 60GHz, how would it be possible for processors (which are operating at less than 1/10th of that clock rate) to process that sampling rate?

Yes. The key here is the difference between frequency and bandwidth.

The radar isn't using the entire 0 Hz to 60 GHz band, it will be using something like a few GHz or sometimes much less. i.e. 60-64 GHz

Also much of the processing isn't done on general purpose processors but in FPGAs or ASICs which can do lots of the parallel computation very fast.

For comparison 802.11ac has a max of 120 MHz channels, and that's cheap and everywhere these days (but runs on 5 GHz).

There are lots of basically tricks to reduce the amount of data in successive stages so that the processing is quite possible.

Re: mmWave radar, you won't see it coming

#42

Post by kjeetgill »

samatman wrote: post #34
krasin wrote: post #5

Earlier quoted context omitted.

I worked with mmWave radars previously, but not professionally. In my opinion, it would be quite challenging to extract enough features from the current generation of mmWave radars, such as TI IWR1642 ([1]) which have around 4 receivers and 2-3 transmitters, because the incoming data, while having a lot of temporal resolution is very limited in spatial resolution. With greater number of antennas something like what y…

Sorry, don't buy it. Gait analysis is excellent at identifying people, and that's projecting from a 2D image at a distance. Anything which can draw a moving voxel cloud around a human is going to figure out who that human is eventually.

I don't disagree but I think this version of privacy is reductive.

Plenty of real world privacy exists on a spectrum. My family knowing I'm in the bathroom is a far cry form them pointing a camera at me.

If stores track you "anonymously" with this ... Who cares? It's less invasive than the ubiquitous security cameras they have pointed at you.

Re: mmWave radar, you won't see it coming

#43

Post by hornej »

cj wrote: post #30
wavesquid wrote: post #9

Earlier quoted context omitted.

You don't need to identify a face; you can identify people by Gait. If you can resolve something as big as a leg you've got enough, as long as you have it over 10 seconds or so.

(Genuinely curious) how do you know this?

There has been research done on gait recognition https://techxplore.com/news/2018-08-artificial-neural-networ...

mmWave can be used to identify unique traits http://www.cs.ox.ac.uk/files/10889/%5BDCOSS19%5DmID.pdf

Re: mmWave radar, you won't see it coming

#44

Post by squarefoot »

cj wrote: post #30
wavesquid wrote: post #9

Earlier quoted context omitted.

You don't need to identify a face; you can identify people by Gait. If you can resolve something as big as a leg you've got enough, as long as you have it over 10 seconds or so.

(Genuinely curious) how do you know this?

It doesn't even need a radar sensor. Everyone moves in a different way, so that extracting patterns from the phone accelerometer can help to identify a person. Two people carrying the phone in the same pocket or hand will produce very different patterns that can be analyzed to extract the different behavior. All it needs is one chance in which that pattern is successfully paired with the person's identity, and from that moment on all their activities can be identified.

Re: mmWave radar, you won't see it coming

#46

Post by samatman »

kjeetgill wrote: post #42
samatman wrote: post #34

Earlier quoted context omitted.

Sorry, don't buy it. Gait analysis is excellent at identifying people, and that's projecting from a 2D image at a distance. Anything which can draw a moving voxel cloud around a human is going to figure out who that human is eventually.

I don't disagree but I think this version of privacy is reductive. Plenty of real world privacy exists on a spectrum. My family knowing I'm in the bathroom is a far cry form them pointing a camera at me. If stores track you "anonymously" with this ... Who cares? It's less invasive than the ubiquitous security cameras they have pointed at you.

I have no opinion on your reply, I was discussing technical feasibility in response to someone claiming it was infeasible. The normative claims aren't germane or particularly interesting to me.

Re: mmWave radar, you won't see it coming

#48

Post by fy20 »

idontwantthis wrote: post #3

> Because mmWave radar doesn’t process visual light, what it sees is not personally identifiable. This makes it an ideal choice for monitoring where a camera would not be appropriate. Is 5mm resolution not enough to identify a face? What’s the difference between a 3d model of a person constructed from high res radar and a black and white photo? The radar sounds even more identifiable. Edit: Couldn’t you construct a m…

In terms of an IoT device or phone sensor form factor, not yet, but in the future I expect it will be possible.

Airport body scanners use millimeter wave radar, and they use software to mask the image so it isn't personally identifiable. There are even passive versions that just use background radio waves in a compact form factor:

https://www.qinetiq.com/en/what-we-do/services-and-products/...

Re: mmWave radar, you won't see it coming

#49

Post by transpute »

> Because mmWave radar doesn’t process visual light, what it sees is not personally identifiable.

With machine learning improvements, identification and more are possible. From a 2021 paper on IEEE 802.11bf Wi-Fi Sensing, https://arxiv.org/pdf/2103.14918.pdf

> Indeed, it has been shown that SENS-based classifiers can infer privacy-critical information such as keyboard typing, gesture recognition and activity tracking ... since Wi- Fi signals can penetrate hard objects and can be used without the presence of light, end-users may not even realize they are being tracked .. individuals should be provided the opportunity to opt out of SENS services – to avoid being monitored and tracked by the Wi-Fi devices around them. This would require the widespread introduction of reliable SENS algorithm for human or animal identification.

Prior discussion of WiFi Sensing:

Jan 2022, https://news.ycombinator.com/item?id=29901587

May 2021, https://news.ycombinator.com/item?id=27123493

400+ research papers on wireless activity sensing, showing steady improvement in detection techniques, https://dhalperi.github.io/linux-80211n-csitool/#external

Today, specialist devices or targeted attacks can monitor human activity through walls and closed doors. But that's a world away from the ubiquitous transparency scheduled for commodity WiFi 7 in 2024. If regulators or lawyers don't step in, homes and some businesses may need RF shielding.

Re: mmWave radar, you won't see it coming

#50

Post by synthos »

hornej wrote: post #2

I've been following and building mmWave radar stuff for a little over a year now and I wanted to write an intro to help anyone get up to speed on how it works, why it's special, and what's been happening in the space.

How is the power consumption?

Is it sensitive to noise or interference?

The VR headset application appeals to me. If headsets could be dumb terminals they would be a lot lighter and untethered wouldn't suffer from performance loss.

Post reply on HN