Two-wire dc communication system and transceiver
Two-wire signal transmitter and method for maintaining integrity
Two-wire television interphone system
Two-wire transmitter with totalizing counter
Two-wire, multiple-transducer communications system
Ultrasonic tape intrusion detection system
Ultrasonic wave type alarm device
Umpire's counter
Unbalance vector display device and process
Universal intelligent group guidance system and method
Universal serial bus extension cable
UPS signaling state
Vacuum activated switch and container
Validity signal apparatus for monitoring a line boundary
Vandal-resistant call box
Variable alarm for communication devices
Variable candela strobe
Variable candela strobe with constant trigger voltage
Variable distance marker
Variable intensity visual signaling system