T R

Radio transmitters and receivers for underground use; wireless extension systems for tunnels, namely, distributed antenna systems comprising base interface units to connect to base radios, in-tunnel network boosters, in-tunnel cabling and tunnel network antenna; distributed antenna systems comprising interface units to connect to base radios, network boosters, repeaters, and signal antenna specifically for railroad and mass transit, that extends two way wireless data and voice signals in zones that are normally shielded from coverage by conventional wireless systems; Wireless RFID Tracking System which utilizes RFID beacon devices and readers to send, receive, store and re-transmit data via wireless connection