A controlled current signalling device for use with transmission lines, said device including a current source adapted to be coupled across the transmission lines and having a high output impedance in comparison to the impedance of transmission lines and modulation means adapted to modulate the current source in accordance with a sensed input signal, said current source adapted to maintain its high output impedance during modulation thereof.

A loop communicating system in which the loop is conductors alternated with diodes. A partial loop electrical circuit has brushes that contact the loop so as to complete the partial loop using a single conductor of the loop or, by contacting two conductors of the loop, incorporated the diode between two conductors into the partial loop. The differences between these two arrangements electrically is used to signal the changes in position of the partial loop on the loop.

A pressure pulse generator for use in transmitting pressure signals to surface in a fluid-based drilling system having a housing having an inlet to admit drilling fluid to the interior of housing, and an outlet to discharge fluid from the interior of the housing; a control element slidably mounted in the housing between an open and a closed position, the control element generating a pressure pulse in the supply of pressure fluid when the control element takes-up the closed position; a control pa...

Method systems and apparatus for signalling within pipelines. The systems methods and apparatus make use of a unit locatable within a tubular piece of metallic structure for the transmission and/or reception of signals. The unit includes a magnetic material core (6) which provides a path for magnetic flux through the unit (4). A coil (81) is wound around a portion of the magnetic material core (6) to allow the detection and/or application of magnetic flux in the magnetic core (6). At each end of...

A method of transporting Call Control related signalling information between a first telecommunications network employing Signalling System No. 7 (SS7) signalling and a second telecommunications network in which Call Control functionality is handled by Media Gateway Controllers and Bearer Control is handled by Media Gateways. The method comprises routing Call Control related signalling data between the signalling network and a Media Gateway Controller through a Media Gateway controlled by said M...

A compact vehicle signalling light having a multi-reflector concave mirror which provides maximum light yield. The mirror includes a first reflector which is convergent and enveloping with respect to the light source and a second reflector formed near the apex of the mirror which reflects light rays passing around the light source without interfering with it. The vehicle light further includes a lens which cooperates with the reflectors to generate a light beam which complies with regulatory sta...

RGS8 polypeptides and polynucleotides and methods for producing such polypeptides by recombinant techniques are disclosed. Also disclosed are methods for utilizing RGS8 polypeptides and polynucleotides in diagnostic assays.

A method and an apparatus of adding an application in a signal messaging network without adding a node in the network. An application platform is connected between two nodes by means of a first link and a second link. The application platform only comprises OSI stacks to layer 2 after which a link management and any possible application takes over. The link management will mirror the status of the two links to thereby keep the application platform unobtrusive, i.e. giving appearance of it not be...

Signalling messages conforming to different signalling protocols in a distributed switch telecommunications network are correlated by associating specific pairs of messages according to parameters they have in common. Inter-MGC IAMs and SS7 IAMs are correlated by the combination of Calling & Called address parameters; the connection descriptor parameter included in inter-MGC IAMs and MGCP OK messages can be used to correlate these messages; and the MGCP OK message can be correlated with the MGCP...

Data processing systems (2) having power management mechanisms (8, 10, 14, 16) for one or more power domains (6, 12) utilise an active high power enable request generated by a power controller (8, 14) to trigger a power supply unit (10, 16) to generate a required power supply signal. Pending valid generation of this power supply signal, or more generally when a power domain is switched off, an active signal which is generated by the power controller (8, 14) and applied to the reset input of the ...