Apparatus (30) comprises a battery power supply, a radio-frequency transceiver, a multi-element antenna, and processor and memory. Software causes the apparatus (30): when in an idle mode, to broadcast positioning service advertisements and to refrain from broadcasting positioning packets, when in a positioning mode to broadcast positioning packets from each of the elements of the antenna (32A-C) such as to allow a mobile device (10) to determine a bearing to the mobile device (10) from the apparatus (30), and to transition from the idle mode to the positioning mode in response to receiving either a) a wake-up command or b) a positioning packet, from another apparatus including a multi-element antenna. The apparatus (30) may comprise a Bluetooth Low Energy transceiver; and software that causes the apparatus (30): to transmit advertisements for positioning services on a first channel; and to broadcast positioning packets on a second channel such as to allow a mobile device (10) to determine a bearing to the mobile device (10) from the apparatus (30), wherein the first and second channel are on different frequencies.