How do anti-theft alarms work in grocery stores?

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I know that clothing stores items usually have some kind of RFID tags in them. But what about food items in grocery stores, say, a carton of milk? Are tags still embedded in them?

I’ve also read that scanning a barcode esentially deactivates the tag inside. But wouldn’t that mean that people can scan items and then not pay without setting the alarms off?

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Anonymous 0 Comments

I work with these kinds of systems. The first thing you need to know is that security is sometimes just theatre. The door scanners, sometimes they are fake! Just intended to prevent shoplifting by making it look like you’ll get caught.

The next thing to understand is that there’s 2 basic kinds of RFID system. The first kind is super basic just radio frequency (or magnets). For these kinds of systems the tag needs to be removed, or phsycaly deactivated (normally by rubbing it against a magnet). You’ve likely seen the plastic tags on clothing, this is the kind that needs to get removed. You’ve likely had a clerk rub the sipie of a book against a special block, that’s a magnet deactivating the device in the spine of the book. This is how the old anti theft systems all worked up to about 10 years ago.

The new systems are actual RFID systems. Each RFID tag transmits a unique number, like 100% a unique number. If you have 2 large blue sweaters each one would transmit a different number.

These RFID tags are normally embedded into the actual paper of the price tag attached to the item for sale (so not common in grocery stores). In that kind of system the RFID tag never gets deactivated or removed, it’s kind of always active even when you take it home and throw it away. In that kind of system when the clerk sells an item, the POS knows the ID number and notes that specific item as sold. It’s not just scanning the tag that does this, it won’t happen until you actually complete the full transaction.

Every person that leaves the store passes through the gates (or under the reader) and the RFID tag is read, compared against the database of items in the store and if the item has been sold, no alarm sounds. But if the item is not listed as sold, an alarm goes off.

The new systems are better for lots of reasons but in terms of anti theft it’s because you know what was actually stolen. In the old kind of RF system the alarm would go off the the thief ran away and you’d have no clue what they actually took just that an active tag left the store. But the new RFID systems are significantly more expensive, buying the paper price tags with the RFID chips in them is expensive, buying the machines that print the tags is expensive and the readers in the stores are more expensive. But much better inventory control.

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