Patent ID: 8922431

Claim:
A collision avoidance apparatus which includes: a UHF (Ultra High Frequency) transceiver operable to send and receive UHF signals in the form of UHF data packets of short burst duration in electric field (E-field) mode, the UHF signals having long range but low resolution; a VLF (Very Low frequency) transceiver operable to send and receive VLF signals in magnetic field (H-field) mode, the VLF signals having short range and medium to high resolution, and being impervious or at least resistant to obstructions; a SHF (Super High Frequency) transceiver operable to send and receive SHF signals in the form of SHF data packets in rapid succession in electric field (E-field) mode, and in which time of flight the SHF signal varies depending on the distance between transmitter and receiver, the SHF signals having medium range and high resolution; a control module comprising a processor and a non-transitory computer-readable medium having stored thereon a computer program configured to direct the operation of the processor, and hence of the apparatus, when executed by the processor, to: detect receipt of a signal via at least one of the transceivers to determine that a second signal-transmitting apparatus, and hence an object associated with the second apparatus, is proximate; determine miniscule differences in the time of flight of the SHF signal; determine or at least estimate a distance of the second apparatus by analysing the characteristics of the received signal(s) and the measured time of flight differences such that the disadvantages of each transmission technology (UHF, VLF and SHF) is compensated for by the advantages of the others; and determine whether or not an alert is to be issued, based on the nature of the received signal; and an output arrangement operable to issue an alert in response to instruction from the control module to do so.