Could I make a little gun and just walk around through the parking lot and aisles of the supermarket and freeze all the carts in place?
Could I make a little gun and just walk around through the parking lot and aisles of the supermarket and freeze all the carts in place?
Im not sure exactly how the system works, but if I were designing one, there would be 3 approaches I can think of.
The first is to equip the lock with a GPS system and dictate that it locks if it’s not within range of a particular location. This one would be the most expensive to implement, but should come with minimal opportunity for messing with it.
Next down the list is each lock is equipped with a radio to connect to a wifi or sub-GHz broadcaster, and as soon as it misses enough heartbeats to a central control point, it locks the wheels. This could be disrupted by jamming the signal, but jammers of this type are highly illegal, and easily trackable.
Last is the cheapest option, which is to include an RFID module tied to the lock and a system to broadcast a signal at the perimeter. If a cart comes within range for a long enough period then the RFID tag is activated and the wheels lock.
I suspect it’s probably a sub-GHz radio situation, with the broadcast power tuned to be within a few hundred meters of the store. If you had some kind of SDR you could probably pinpoint the signal they use and repeat it, letting you wheel a cart outside the zone, but as soon as you stop the signal the wheels will lock.
It looks like they’re SubG. The lock signal broadcasts on the buried line, and at least in the one manual I found, they can also lock all, lock all in a lot, and optionally lock singles via serial number (there’s an inventory system). There’s a directional handheld device that can be used within a couple of feet of an affected cart.