Is anyone else having a problem with their tablets setting off the anti-theft alarms near the store entrances? I went out shopping in three stores, and in all three the alarm went off when I went in and when I left. It's getting kinda irritating.

I have an N810. Bluetooth was on, which usually isn't, so I'm thinking that maybe that has something to do with it, even though it uses RFID?

No, but it might depend on the type of alarm. Had no issues with CheckPoint units locally. Are you sure it's just not something you bought that wasn't deactivated properly?

One day, as I went from store to store, I kept setting off the alarm every in every shop I visited. In each case, they waved me through because I guess I don't look like their stereotype of a shoplifter. Eventually I got to the inkjet recycling store and handed over the old cartridge that I had been carrying, and the alarms stopped going off.

The next day the supermarket had a security guard by their alarm, so I told him about the inkjet cartridge the day before. He acknowledged that they often set off the alarms, but said that some brands of mobile phone were even more problematic, so it's quite possible that a tablet could set them off too.

I don't think Bluetooth is anything to do with it; the alarm is picking up a re-radiated signal caused by some kind of resonance and nonlinearity (which generates harmonics) in some circuit of the device.

I have now learned how to stop my inkjet cartridges setting off the alarms. The main trick is to walk right in the middle of the doorway rather than next to one of the two sensor towers. It's also important to walk at normal walking speed or slower, as a brisk walk seems to set it off every time. Finally, I have found that at my supermarket one of the two entrances is less sensitive than the other. Now I no longer set off the alarm, except when I forget to walk in the middle.

I suppose when these alarms are designed they are carefully tuned to have minimal false alarms, but in realistic use without regular maintenance they become less reliable.

Roger

Most definitely. The calibration tends to drift during the operation. In a store I worked in it drifted so much that handling merchandise near the front door started setting it off. Eventually it requires a field tech to come out to recalibrate.

The pads that disable the tags tend to drift, too. Sometimes to the point where they'll disable all the tags around the cash register and sometimes to where they wont disable any at all. Which is particularly obnoxious as every person walking out of the store ends up setting the alarm off.

The vast majority of false-positives I noticed came from merchandise purchased elsewhere that hadn't had its tag deactivated. Makeup seems to be a popular culprit.

This was all with a CheckPoint system (which uses RFID), though, so I'm not sure about magnetic systems.

was at the customer end of a faulty eraser ones. bothersome stuff.

i have also experienced stuff from one store setting of alarms in another. the person working the store with the alarms going off seemed familiar with the problem as his first question was if i had anything from the first store...

i also heard about kids peeling of alarms and slipping them into peoples pockets...

I'm sure it was the tablet, because when it happened at the third store, I stopped and took my n810 out, waved in between the two sensors, and they went off.

It's just that this hasn't happened before, but yesterday it happened every single time I crossed one of the sensors.

I haven't done that before at all... mhm.

It's a geek sensor!

I used to put those theft prevention tags in the liner of my roommate's jacket and then sew it back up. Maybe that's what happened.

Such evil!

Hee.

bluetooth could be the culprit if the alarm operates in the same frequency band (2.4ghz for bluetooth)... or if the antenna in your tablet is not tuned correctly (durring manufacture) thus causing it to radiate inefficiently and give off spurious signals at multiples of the frequency. (i.e. citizen band radio in the U.S. is in the 27 mhz band and T.V. ch 2 is around 54 mhz... so there you are watching the game and some nut with an homemade CB antenna is messing up the signal by talking to his buddies about how good the game looks now that he has cable T.V.)

Have Fun
Ben