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Comment by justrealist | Hacker News Reader

Speed throttling means the car has to know the posted speed limit. So will it be illegal to have a car in California without a GPS tracking your location in real-time?

Or will it simply be illegal to have a car without cameras tracking everywhere you go, to read speed limit signs?

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The draft bill [1] appears to require GPS, yes:

> Article 19. Speed Limiter Technology

> 28170. As used in this article, “intelligent speed limiter system” means an integrated vehicle system that uses, at minimum, the GPS location of the vehicle compared with a database of posted speed limits, to determine the speed limit, and electronically limits the speed of the vehicle to prevent the driver from exceeding the speed limit by more than 10 miles per hour.

[1] https://leginfo.legislature.ca.gov/faces/billTextClient.xhtm...

While it sounds nice, gps jitter will cause a lot of issues unless it just defaults to the highest speed in a couple block radius

Good thing GPS spoofing is so hard to do (heavy sarcasm)

Also, good thing GPS spoofing doesn’t happen regularly in California (also sarcasm)

Also, good thing that GPS works flawlessly in canyons, underpasses, tunnels, etc… (if it’s not yet obvious, is sarcasm too)

This feels like an “idea man” level concept.

This would not work well for my car right now - the GPS sometimes decides it's a few blocks to the right on the surface streets instead of on the highway. :')

I think the legislators who thought this was a great idea should be required to trial the technology. If their car suddenly brakes on the freeway, causing a massive crash, they should be personally liable and also charged with reckless driving or worse.

That could be actually disguise for installing those tracking devices and gather even more data with gaining more control

Some cars already have completely offline systems that read traffic signs. They’re pretty simple to design computers to read because they’re in a standardized format. They do have less than perfect accuracy, however.

The highway could also broadcast the speed limit, via beacons. That would be more reliable than GPS, but GPS doesn't track your location. A GPS receiver is just that--it receives, never broadcasts. It needn't record anything in order to enforce the speed limit.

Who’s going to pay for that?

Who pays for highways now? What kind of question is that?

This also allows highway speed limits to vary based on conditions, which is better than the status quo.

Not necessarily. The vehicle can communicate with the speed limiter pole to obtain the speed limit and adjust its speed accordingly. There are no cameras, no GPS, and the speed limit can be set dynamically.

What information will it pass to those poles, if any?

Why does it need to transmit anything at all?

> communicate with the speed limiter pole

As a person who's reverse engineered O(1000) "secure" devices and O(100) "secure protocols", let me just laugh aloud at the thought that this will be done right!!!

Basically: new fun use for SDR just dropped! Randomly broadcast speed limits of 1mph near the higway.

There is no security at all on many infrared traffic signal overrides. You can easily hack them, you just have to decide if it’s worth the risking being charged with a crime that carries a minimum 6 month prison sentence.

How would that work? Cell phones record your location as a side effect, because they can be seen by multiple cell towers.

But in this scheme, your car would record your location as the primary effect. You can still see multiple limiter poles. How do you know which one applies to you? You need to determine your location for that. (Unlike with cell phones, the pole with the strongest signal is not necessarily the one that applies to your position.)

If the limiter poles can receive as well as broadcast, they will also record your location, just like cell towers do. But even if they can't, it's necessary for the car to do so itself.

Very problematic. How does the vehicle know which pole to talk to? How does it know it’s not incorrectly communicating with a pole on a parallel or perpendicular road, for example? Or indeed a road that is below another road, as sometimes occurs in urban environments. So so so many issues. How does the vehicle reliably know which road it’s on? How is the system kept invulnerable to bad actors? Etc etc

I don’t agree with the proposed solution being entertained here, but all of these problems are solved. Because automated tolling systems work this way.

Automated rolling systems work on specific roads designed for it.

The suggested mandate is for all roads, which introduces crosstalk errors in the system decoding the environment.

There are tolling systems that assign different tolls to different lanes and different vehicles on the same road. It would be prohibitively expensive to put on all roads, but the technology exists and it works.

Either via RF or line-of-sight IR.

The RF method works the same way ILS for aircraft works: multiple lobes of differing frequencies to a compatible receiver that will only accept the data if both frequencies are present and the interference pattern matches the conditions that it is looking out for.

IR is considerably simpler and would require a receiver to pick up on a well-aimed beam.

For bad actor mitigation, they could put a signature at the end of the speed data that signs the packet with the priority, route, datestamp, and TTL. The priority field could help enforce slower limit around construction zones.

Now I can only imagine fun times when those get stolen from road works... And then relocated to some other places. Maybe just simple plastic bag used to cover the number...

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