1. A system comprising: a transmitter for transmitting wireless signals in all directions within a range of directions, the range of directions including at least all directions in a plane; a receiver for receiving echoes of the wireless signals from any direction in the range; a processor for processing the received echoes to derive echo data signals indicative of the distance of the system to a plurality of reflective surfaces; and an adaptive system for: during a training stage, learning at least one association between the echo data signals and the position of the system based on training data composed of records of echo data signals and associated system position data, and during a working stage, using the echo data signals and the learnt association to determine the position of the system.