Mobile alarms generally consist of a fob kept in a pocket or bag, and a tag that can be fixed to any portable device such as a laptop, phone or camera. An alarm sounds when the fob and tag are more than a set distance apart.
But this raises the issue of what the device owner is supposed to do if this happens during a theft. Street thieves rarely work alone but instead roam around in pairs, one distracting the victim while the others rifle through bag or pockets.
A new product launched overseas called Nio, from Edinburgh-based Tenbu Technologies, cannot eliminate this possibility, but does allow users to specify one of three different ranges at which the alarm will trigger.
The alarm can be set to go off at close range, or at 20 metres away where there is less chance of physical contact with a thief.
Fraser Ritchie, marketing manager at Tenbu, suggested that the alarm is most likely to be triggered by absentmindedness, for instance when a user leaves a laptop or mobile phone in a cab or a cafe.
"We are not in the business of trying to panic people into thinking they are a target of thieves every time they leave their front door," he said.
Ritchie added that the Nio is unique in using a Bluetooth-enabled mobile phone instead of the usual wireless fob. The tag can go on any portable device, and the alarm sounds on both so the Nio protects two devices at once, or more if extra tags are purchased.
Ranges are estimated from the power Bluetooth requires to establish a link, and the phone can be set up to sound a different alarm for different devices. Most major phones are supported.
Ritchie admitted that the alarm could precipitate a potentially dangerous situation, but believes that a thief would be more likely to drop an alarmed device rather than get involved in a confrontation.
A Scotland Yard spokesman acknowledged that wireless tags can help protect property.
"What you do if the alarm goes off is up to you. But we would warn you to think carefully before trying to become a have-a-go hero," he said.
A Nio tag with mobile phone software is available online overseas.