An apparatus, system and method for emergency under-door signalling includes a paddle in the form of an elongate strip of stiff plastic material bearing on its surface a phosphorescent marker. The strip may be slid under the door of an apartment or other building unit in an emergency situation, for example a fire, to indicate to emergency response personnel that the unit is occupied. The system includes a strip storage mechanism, for example a hook that will mount the paddle on a wall and an ind...

Message switching organization for exchanging data messages between function or signalling units within the memory of a processor controlled telecommunications system. Each such function unit has its own program and its own data storage, and the program of a unit has access only to the data storage of its own unit. Messages transmitted between units are of two types, those including information regarding the destination unit address and those omitting destination unit address. Each unit has a me...

A signalling system adapted for digital signals includes a signal transmitter, a signal receiver and a connection which connects the transmitter to the receiver. The transmitter includes an output buffer which has at least one transistor connected to the lowest level of a signal supply voltage, such as to "0" potential or earth potential. Driving or steering of the transistor in response to a received control signal causes the transistor to switch from a state of high impedance to a state of low...

A signalling circuit which outputs reference potential at either a first or second output, dependent on an input signal. The signalling circuit operates reliably in a large range of operating voltage with an optimally low power consumption. A constant current circuit and a parallel connection of two current paths fed by constant current are provided in a circuit connected to an operating voltage source. The first and second outputs are respectively connected to reference potential via respective...

An improved emergency signalling device for use by skiers, hunters and other persons who may be exposed to the outdoors, remote from civilization, and who may in the course of their avocation or occupation become injured or disabled while far removed from contact with assistance. The device comprises a package, which may be secured by straps to a limb or the body of the person, the package containing a signal balloon, a helium container and a reel for paying out a length of tether line together ...

The invention relates to signalling, particularly road signalling, means. A considerable variety of illuminated and reflective signalling means are known to give advice to the driver of a particular vehicle and of great value to the driver of a vehicle during the hours of darkness on unlit roads or in inclement weather where mist and fog shroud a road. Such known signalling means cannot satisfy the important need to give advice to a driver of a vehicle of the presence of another vehicle closely ...

An article of footwear is provided with a normally open reed switch and provides a visual or audible signal when the reed switch is closed. A magnet is provided movable under inertial forces between an ON position where it causes the reed switch to close and an OFF position where it allows the reed switch to open. The magnet is biased to OFF position.

A signalling device which is mountable on a rural route mailbox comprises a housing which encloses a light fluorescing material and an activating element which extends exteriorly of the housing. The activating element is triggered by opening the mailbox door, which moves the light fluorescing material to an exteriorly observable position within the housing where it emits a visual signal to residents that mail has been received.

A signalling device for scuba divers uses their compressed air supply to drive a piston (42, 51, 72) against a diaphragm (22, 48, 49, 57, 63, 90) to generate sound in water against the diaphragm. A bistable valve 34, 52) switches pressurised air alternately to opposite ends of the piston (42, 51, 72) to cause it to reciprocate and repeatedly impact against the diaphragm (22, 48, 49, 57, 63, 90). Air is exhausted from the cylinder (11, 54, 70) through ports (27, 28, 29, 30, 110, 111, 73, 74), the...

A code signal representing a sequence of code symbols carrying digital information is generated with the frequency components of the code signal being essentially confined to a preselected signalling band lying within the bandwidth of an audio signal within which the code signal is to be embedded. The audio signal is continuously frequency analyzed over a frequency band encompassing the signalling band and the code signal is dynamically filtered as a function of the analysis thereby to provide a...