Abstract: A system (100) for detecting at least one object in environmental conditions of poor visibility, comprising: a ranging device (10, 30) configured to receive a set of signals; at least one further ranging device (50) configured to receive at least one further set of signals; and a processor (40) configured to gate the set of signals based on the at least one further set of signals thereby to identify at least one subset of the set of signals, the at least one subset of signals relating to at least one object.