Xfinity using WiFi signals in your house to detect motion • Hacker News Board

Re: Xfinity using WiFi signals in your house to detect motion

#411

Post by vel0city » Tue, Jul 01, 2025, 2:39 PM UTC

puppycodes wrote: post #129

vel0city wrote: post #112

Earlier quoted context omitted.

This technology doesn't rely on you actually having a WiFi device on you. It can detect presence/motion by changes to the standing waves of the EM propagation throughout the room. As the salty water meatbags move from room to room we change how the reflections and scattering patterns of 2.4 and 5GHz waves move. Studying these changes and some calibration, you can even determine small changes (like is the person on th…

im very skeptical of the accuracy claimed. The layout and complexity of objects in most homes to do this is way to awkward to work reliably. For someone breathing or a heartbeat you need much higher GHz signal. Usually this is done at 30ghz to 60ghz. The power flux leaving the antenna has an inverse square drop off rate which makes this basically impractical unless your standing directly in front of it.

I do agree some of these claims are pretty extreme. I wonder if it does work what the reliability of things like breathing and heartbeats. FWIW, some of these systems do incorporate 60GHz signals in their analysis, but as you mention dealing with 60GHz is incredibly challenging even in something like a residential building.

I'd really like to actually see it in person to really grasp the limitations.

Re: Xfinity using WiFi signals in your house to detect motion

#412

Post by nightpool » Tue, Jul 01, 2025, 2:41 PM UTC

Latty wrote: post #339

dcow wrote: post #326

Earlier quoted context omitted.

Setting a language preference cookie is not tracking and I will die on that hill. The law requires consent before using a cookie to store even a mundane option that was just directly modified by a user. Collecting a crash report is not tracking a user. Even first party product analytics is not tracking a user. Tracking a user across domains using a 3rd party aggregator to serve add and do attribution is the evil. And…

A language preference cookie is not tracking under the GDPR and doesn't need to be promoted for. Of course, if you take that language preference and feed it into your advertising to identify and target people, then it becomes tracking.

You're correct under the GDPR but incorrect under the older ePrivacy Directive. EU sites need to be compliant with both, and so the cookie banners persist.

Re: Xfinity using WiFi signals in your house to detect motion

#413

Post by ndriscoll » Tue, Jul 01, 2025, 2:53 PM UTC

dcow wrote: post #300

idiotsecant wrote: post #274

Earlier quoted context omitted.

What law do you think mandates those annoying cookie popups?

It would be nice if you could argue, “well, just be a good site and don’t use marketing cookies”, but the ePrivacy Directive requires consent for performance and preference cookies too. Perhaps a liberal reading arguably allows classification of certain statistics and preferences functions to be strictly necessary, like “I wouldn’t provide this service without crash reporting because I’d go insane so it’s strictly ne…

Yes that's the point. You don't need those things. The idea that a news article or blog post or e-commerce page could "crash" is ridiculous, and the law shouldn't humor that excuse. There's been standard ways to declaratively define such pages since before scripting frameworks gained popularity. Use those standard ways. If you're really building an app and need to performance test, buy some hardware in your target range. Privacy aware users block things like Sentry.

Re: Xfinity using WiFi signals in your house to detect motion

#414

Post by nightpool » Tue, Jul 01, 2025, 2:55 PM UTC

jraph wrote: post #360

dcow wrote: post #326

Earlier quoted context omitted.

Setting a language preference cookie is not tracking and I will die on that hill. The law requires consent before using a cookie to store even a mundane option that was just directly modified by a user. Collecting a crash report is not tracking a user. Even first party product analytics is not tracking a user. Tracking a user across domains using a 3rd party aggregator to serve add and do attribution is the evil. And…

> The law requires consent before using a cookie to store even a mundane option that was just directly modified by a user Nope. That's exactly why the evil cookie modals are not on the GDPR but only on the sites that want to track you and now need to ask you for your consent before doing so. That's usually exactly where good faith GDPR detractors are wrong, and that's what needs to be repeated again and again in thos…

You're correct that the GDPR specifically doesn't require this, but you're incorrect that "the law" doesn't—the 2004 EU ePrivacy Directive requires affirmative consent for all cookies, and it's being enforced much more strictly now in a post-GDPR world

Re: Xfinity using WiFi signals in your house to detect motion

#415

Post by 93po » Tue, Jul 01, 2025, 3:07 PM UTC

Aurornis wrote: post #41

In case anyone is skimming the headline and comments: It's not enabled by default. This is an optional feature that you have to find, turn on, and then select up to 3 WiFi devices to use as reference signals: > Activating the feature > WiFi Motion is off by default. To activate the feature, perform the following steps: The actual title of the article is "Using WiFi Motion in the Xfinity app".

The visibility of the feature for users may be "off by default" but that means nothing in terms of what Comcast is actually collecting, storing, and sending to third parties.

Re: Xfinity using WiFi signals in your house to detect motion

#416

Post by jraph » Tue, Jul 01, 2025, 3:10 PM UTC

nightpool wrote: post #412

Latty wrote: post #339

Earlier quoted context omitted.

A language preference cookie is not tracking under the GDPR and doesn't need to be promoted for. Of course, if you take that language preference and feed it into your advertising to identify and target people, then it becomes tracking.

You're correct under the GDPR but incorrect under the older ePrivacy Directive. EU sites need to be compliant with both, and so the cookie banners persist.

Are you sure? That's new to me.

https://en.m.wikipedia.org/wiki/EPrivacy_Directive says

> The Directive provision applicable to cookies is Article 5(3). Recital 25 of the Preamble recognises the importance and usefulness of cookies for the functioning of modern Internet and directly relates Article 5(3) to them but Recital 24 also warns of the danger that such instruments may present to privacy. The change in the law does not affect all types of cookies; those that are deemed to be "strictly necessary for the delivery of a service requested by the user", such as for example, cookies that track the contents of a user's shopping cart on an online shopping service, are exempted.

Re: Xfinity using WiFi signals in your house to detect motion

#417

Post by fred_is_fred » Tue, Jul 01, 2025, 3:12 PM UTC

Up next - Comcast will pause ads when it detects that you've walked into the kitchen - or raise the volume. Advertisers can pay extra for this feature.

Re: Xfinity using WiFi signals in your house to detect motion

#418

Post by dvdbloc » Tue, Jul 01, 2025, 3:14 PM UTC

Could I sufficiently foil their mechanism here by not connecting any WiFi devices to their access point and then wrapping their access point with foil? Or would you need to take it all the way and put the device in a faraday cage? I’ve always wanted to build one but never had the motivation. Maybe this will be the impetus I need to finally make one! Like others have stated I use the ISP provided hardware to get around the data cap. But connect nothing to it other than my own router.

Re: Xfinity using WiFi signals in your house to detect motion

#419

Post by JumpCrisscross » Tue, Jul 01, 2025, 3:22 PM UTC

thesuitonym wrote: post #396

JumpCrisscross wrote: post #313

Earlier quoted context omitted.

> the rich and powerful minority is more organized They show up. I've worked on privacy legislation at the state and local level. Barely anybody calls or writes in support. That means barely anybody would turn up to a contested primary election over it, or donate to a challenger, or organise the foregoing en masse . Contrast that with bread-and-butter or activist issues, where it's immediately clear there is politica…

> They show up. I've worked on privacy legislation at the state and local level. Barely anybody calls or writes in support. This is by design. A lot of people talk about RTO in regards to business real estate but there's also the aspect of keeping people so busy and exhausted that they don't show up when it matters.

> there's also the aspect of keeping people so busy and exhausted that they don't show up when it matters

This would make sense if people didn’t show up for anything. They do. Including very overworked folks.

The unfortunate truth is the people most interested in privacy overlap significantly with the politically nihilistic and lazy. They’ve never called their elected or shown up to a town hall and, moreover, never will, because of course it’s useless.

Re: Xfinity using WiFi signals in your house to detect motion

#420

Post by JumpCrisscross » Tue, Jul 01, 2025, 3:23 PM UTC

komali2 wrote: post #365

JumpCrisscross wrote: post #362

Earlier quoted context omitted.

> do their job of representing the people rather than a handful of corporations There is no incentive to represent the civically disengaged. Particularly on niche issues like privacy. > We have no people with any moral compass in charge No system works if reliant on wishing up on a star that people were better. We have a lot of problems with our republic's design. None of them can address problems people don't care t…

The whole point of representative democracy was supposed to be that you elect someone to represent your interests , so you don't need to participate in the day to day mundanity of managing the bureaucracy. The bar rises. The vote was supposed to be enough. If people call in, well, that's not enough, after all, if you really cared, you'd have written an email, or filled out the correct form in the FTC call for feedbac…

> whole point of representative democracy was supposed to be that you elect someone to represent your interests, so you don't need to participate in the day to day mundanity of managing the bureaucracy

According to whom? Nothing in the Federalist Papers or our country’s founding envisions fire-and-forget politics.

> sure wish our world would try more experimentation in governance

The correct place for this experimentation is small governments. And to my knowledge, this experimentation does happen. It just doesn’t necessarily have the effects its framers imagined. RCV didn’t break the two-party system, for example. And public-sector unions have turned into pests.