Abstract: In order to detect and classify objects in a relatively small obstruction-filled space (e.g. underneath a vehicle), a sensing method and apparatus incorporating the use of at least two carefully selected transmission frequencies is provided. In embodiments where the transmission frequencies are radio frequencies, the sensing apparatus can be considered and analysed as a short-range radar system. Alternatively, if the transmission frequencies are acoustic, the sensing apparatus can be considered and analysed as a sonar-based system.

Abstract: A subscriber (100) transmits data on a first data channel. While transmitting, the subscriber tracks the number of collisions it experiences on the first data channel (206). When the number of collisions reaches a threshold value, the subscriber transmits a reassignment request to move to a new data channel. Upon receipt of the reassignment request, a central processor (102) assumes that the first data channel is loaded. The central processor will then compare an incoming data rate to a value to determine if the first data channel is actually loaded, wherein the incoming data rate is measured by the central processor at the time the subscriber requested reassignment.

Abstract: In order to detect and classify objects in a relatively small obstruction-filled space (e.g. underneath a vehicle), a sensing method and apparatus incorporating the use of at least two carefully selected transmission frequencies is provided. In embodiments where the transmission frequencies are radio frequencies, the sensing apparatus can be considered and analysed as a short-range radar system. Alternatively, if the transmission frequencies are acoustic, the sensing apparatus can be considered and analysed as a sonar-based system.