Abstract: According to one embodiment of present invention, there is provided a method of controlling access to a communication network. The method includes receiving a request from a communication device to connect to the communication network, the request including a substantially unique identifier of the device, and determining whether the identifier is contained in a local device database of the network. Where it is determined that the identifier is not contained in the local database, the method further includes authorizing the device to connect to the network, and at a subsequent update of the local device database, determining the status of the identifier from a shared device database, and updating the status of the determined identifier in the local device database with the determined status.

Abstract: According to one embodiment of present invention, there is provided a method of controlling access to a communication network. The method includes receiving a request from a communication device to connect to the communication network, the request including a substantially unique identifier of the device, and determining whether the identifier is contained in a local device database of the network. Where it is determined that the identifier is not contained in the local database, the method further includes authorizing the device to connect to the network, and at a subsequent update of the local device database, determining the status of the identifier from a shared device database, and updating the status of the determined identifier in the local device database with the determined status.

Abstract: A mixer device designed for a TV production control room mixes incoming video signals of PAL, NTSC or MAC standard. To avoid any differences in video signal propagation time through a known video grid, the latter is suppressed, and a grid with narrower band width switches chopping signals selectively controlling attenuations of the incoming video signals in analog multipliers. The chopping signals are derived in operator circuits as a function of effect and dissolve signals designed to chop image planes to be superposed into a resultant image. In particular, amplitude complementarity of the chopping signals between two predetermined levels is ensured, whatever the dissolves and effects selected, and a proportion of a black image signal, transmitted normally during line and field blankings, is mixed during a black fade or a darkening to be created in the resultant image.

Abstract: A television picture superimposing system comprises a video mixer including two variable gain amplifying circuits receiving two input picture signals having a given peak-to-peak amplitude, and an adding circuit for mixing the amplified picture signals into a resulting picture signal. The improvement resides in providing a circuit for deriving a single gain control signal based upon a linear combination of two signals derived respectively from the two input picture signals so that the resulting signal has the given peak-to-peak amplitude. The control signal is respectively applied, via an analog inverting circuit and directly, to gain control inputs of the variable gain amplifying circuits.

Abstract: A television system combines signals representing a picture derived from a foreground scene moving in front of a backing, with a background scene. An input processing circuit mixes a color from the background scene, preferably different from the backing color, with certain colors in the composite foreground and backing picture. A first combiner responsive to the picture and background scene representing signals determines picture zones where false colors are created at transition points between the foreground scene and the backing. At transitions, e.g. a transparent object, between the foreground and background scenes in the resultant picture transmitted by the system, the colors are modified progressively such that a viewer no longer sees the edges or the reflections due to the backing, but rather a slight blur blending perfectly with the background and foreground scene colors.