A system uses an antenna at a portal, the antenna coupled to equipment which can send and receive information to and from radio tags, each having a unique identity. The equipment detects, for example, a tag attached to an asset. The equipment looks to see if an associated badge is in the detection area of the portal. If the badge and asset match, the user bearing the badge is permitted to exit the portal. Otherwise the user is not permitted to exit the portal. An asset such as a ski can be equipped with such a tag, the tag in this case being a low-frequency tag. The low-frequency tag permits locating the ski even if it is not visible because it is under snow.