SUPERMARKET giant Woolworths is quietly trialling beacon technology that will notify selected shoppers of special offers or product updates on their smartphones while they walk through shopping aisles. The trial is restricted to people who were chosen to participate in the pilot. Customers not in the pilot will not be affected by the technology. The beacons are small, low-cost location-based devices that use Bluetooth to communicate with other devices. In the retail sector, customers usually opt in for the service. Beacons work within a 100m radius and are usually discretely placed on shelves where they gather and beam information to customers.