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Comment by mintone | Hacker News Reader

The article suggests that the detectors will detect 2G, 3G and 4G usage, but will recognise if a bluetooth hands-free kit is in use. This sounds like complete snake oil to me, please could someone explain if this is possible?

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Really a guess - an uneducated one at that but I'm guessing it is measuring rf signals transmitting out of the phone more so vs what is being received which is why it will also notify if someone is talking on the phone - the phone will be transmitting. There is probably a measurable difference in rf when a phone is trying to send data vs just acting as a receiver, right? From what I can recall, it generally takes more power for a phone to send data to the tower than to receive it. At the same time, you can measure whether Bluetooth is simultaneously being used.

And what if you're using your phone for navigation? It will still transmit data to google maps or whichever maps service you use, but its usage would probably considered legal.

Heck, your phone could be on silent in your pocket and a push notification might set this off. Your phone still has to transmit the acknowledgment.

I would be amazed if this were reliable enough to survive legal challenge. Personally, it sounds too much like the old "TV detector vans". I'm skeptical.

If you read the article, it says it gives warnings, not fines. It can’t tell if a phone is used by the driver or a passenger anyway.

Well, that settles that then. Just another distracting flashing sign for the driver to deal with.

Not for the people who are using their phone though. For them a push-notification would probably work best ;).

RF signal detectors can pick up what frequency the strongest signal in a range is broadcasting at. I had a cheapy ebay one that at a cost of $30 could pickup my phone ringing or on a call/text on its LTE frequency from about 6 feet away, and that was with it using an untuned antenna as the detector was able to pick up between 100mhz-2500mhz. I'd imagine with a much higher quality detector, a tuned, directional antenna, and a narrower range you needed to cover that you could up that distance several times from the 6 feet I got.

We also had the police employing radar detector-detecting devices 15 years ago that could detect every single radar detector on the market in 2004, and none of those radar detectors were intentionally transmitting a signal: https://en.wikipedia.org/wiki/Radar_detector_detector

It would probably fall foul of hacking laws even if technically possible (which it isn't). They just don't want to say it is a camera based system for fear of... vandalism?

An image classifier with a human check doling out fixed penalties would be more effective than this. So would a warning system on phones that shamed drivers. Neither are within the resources of the police to develop (as nearly all police in the UK are local).

> It would probably fall foul of hacking laws even if technically possible (which it isn't)

Probably not - Computer Misuse Act, s.10:

> Sections 1 to 3A have effect without prejudice to the operation—

> (a)in England and Wales of any enactment relating to powers of inspection, search or seizure or of any other enactment by virtue of which the conduct in question is authorised or required

Definitely - surely most phones will be using/connected-to data services even when not in use?

Especially if you're using GPS software that has live traffic updates, or that downloads maps whilst you are navigating.

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