Retail stores & firearms detection

Discussion in 'Off-topic' started by kkennett, Nov 30, 2006.

  1. kkennett

    kkennett New Member

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    I was talking recently with a good friend of mine who works in marketing retail store loss prevention electronic systems. Apparently a technique commonly used by professional level thieves is the foil lining of bags/purses/coats etc. to mask the field from the inventory control tags; thereby evading the beeping at the door. In response, newer door systems are available which can detect the entry of the foil lined bags. They're basically just metal detectors and they also detect the entry of firearms. What a certain retailer does with this knowledge varies. Apparently most who actively pursue this sort of thing 'mark an exception' in the security control room and then an operator begins to personally follow this person's movements via camera. For those not carrying bags but who create an exception, the assumption is that they are carrying a firearm. I'm sure some legit ladies carry both bags and firearms. This system and issues are completely separate from the emerging RFID tags for loss control, inventory tracking, etc.

    I'm not sure how this would really effect our daily comings and goings. Certainly it could lead to harrassment of lawful carriers by store personnel. They could ask you to leave and you could refuse to patronize their business. My biggest concern is not that the corporate thinkers would not consider lawfully armed citizens in their planning for this technology, but that Joe Blow the Saturday night manager at the big box store may not be particularly well trained and could be a needless irritant. Any thoughts?
     
  2. Malum Prohibitum

    Malum Prohibitum Moderator Staff Member

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    Most "tin" foil today is really aluminum. So, your friend is saying that there are aluminum detectors installed at the entry of stores that detect this small level of foil.

    Does it pick up your friend's hat when he walks in? :lol:



    Seriously, I know from experience thieves do this (although I do not know how it works), but I was under the impression that metal detectors worked on a principle of magnetism. Can they pick up a small amount of aluminum foil, and, if so, wouldn't they be so sensitive as to pick up belt buckles and shoe lasts?
     

  3. kkennett

    kkennett New Member

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    While I am an engineer, I am not an electrical engineer. I don't know if the foil they use is aluminum from the grocery store, or steel. One can buy steel foil from McMaster Carr and have it later this afternoon. I also don't know if the detection devices are looking at the E x B magnetic disturbance of the electrical field (as a metal detector does or a loop detector at a stoplight), or if they are looking at a change in reflectance or transmission rates of radio waves or what. I'm inclined to think it's the latter, knowing what tiny bit I do about emerging retail detection technology. Either way, certainly false positives will occur. My friend is also in marketing these items, so he may not know all the scientific details either.
     
  4. kkennett

    kkennett New Member

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    I should add that I'm positive anything of this sort would have adjustable sensitivity, to account for the store's environment, the spread of the sensors, etc. I'm sure they could be dialed up to detect chewing gum wrappers. If it's a surface area, transmission thing, they could probably differentiate guns from bags. If it's a metal mass thing, then a gun would certainly have more than any foil lining.
     
  5. Malum Prohibitum

    Malum Prohibitum Moderator Staff Member

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    This guy gets watched every time, huh? :D

    [​IMG]
     
  6. Manwell

    Manwell New Member

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    I’ve often wondered if my weapon would set off the security systems at retail stores… has never happened. Not sure if and don’t care if security watches me closely while I’m in a store… carrying or not!

    Manwell
     
  7. jmorin

    jmorin New Member

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    I work in warehousing/logistics and the use of foil to mask radio signals from tags on/in the products makes sense to me.

    Warehouses have experienced the same difficulties although the technology is improving. The readers on dock doors of warehouses read the passive tags as products are unloaded from a trailer, onto a warehouse dock. However, pallets of dense metal or liquid products that contain passive RFID tags are difficult to read - I think the read rate would be as low as 50 or 60% (again, it may be better now).

    The tags inside or on the store's products are simply low-tech passive RFID tags as well, and objects that looks like metal detectors at the store's entrances and exits are simply readers. But readers have a difficult time "finding" those tags when tags are buried among metals and liquids. But these readers are not metal detectors.

    Here's a more technical explanation:

    The system consists of a tag, which is made up of a microchip with a coiled antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves that form a magnetic field when they "couple" with the antenna on the RFID tag. A passive RFID tag draws power from this magnetic field and uses it to power the microchip's circuits. The chip then modulates the waves that the tag sends back to the reader and the reader converts the new waves into digital data.
     
  8. Broadside Bob

    Broadside Bob New Member

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    Someone said they've never set off a sensor (when leaving the store presumably). In this case, kkennett is talking about a system where you would walk through a turnstyle as you ENTER the store. The machine is not going to start beeping when it detects something (well, not where you can hear it). It alerts the people if in the backroom. Unless one of their security people chooses to challenge you (presumably because they thought they saw you stuffing something down your pants), you would never know. A firearm could set it off every time, and you'd never be the wiser.

    I've never even heard of this kind of system...just pointing out what the OP said.

    OTH, MP's tin foil hat theory sounds feasible too!! :lol:
     
  9. Malum Prohibitum

    Malum Prohibitum Moderator Staff Member

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    Well, I have sat in on loss prevention rooms and watched what they do. They monitor the suspicious characters with cameras that are all over the store.

    Now, back in those days there was no metal detector at the entrance, but I would be interested in hearing more about it. Of course, if you open carry, none of this matters anyway.

    It does seem to me that a metal detector sensitive enought to pick up foinf would also hit on belt buckles and such.

    I also know nothing about detecting aluminum with a metal detector.

    Is it actually a "metal" detector, or a ferrous detector? I know nothing about how these work.
     
  10. ICP_Juggalo

    ICP_Juggalo Active Member

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    At risk of sounding like a nerd, Aluminum is what is known as "transitionary element" on the periodic table of elements. Which means it has the characteristics of metal - shiny, conducts electicity, but not all the properties meaning it is not responsive to magnetic fields.

    So based on that, I would conclude that pure aluminum would not be detectable in a metal detector. Now aluminum compounded with other elements, such as tin - i.e. aluminum foil. Might be detectable because of the presence of tin.