Abstract:
A system for surveillance of a delimited area within which people move, wherein at least one hollow optical fibre is configured for extending through the area and is provided throughout its length with a plurality of holes that set an internal channel of the fibre in communication with the outside of the fibre itself. There is provided an optical source configured for supplying the optical signal to one end of the hollow optical fibre and a sensor designed to detect at one end of the hollow optical fibre the optical signal transmitted throughout the length of the fibre itself. A processing unit is configured for examining the spectrum of the optical signal detected by the sensors in order to detect the presence of toxic agents present in the area and drawn into said channel.
Abstract:
Before modulating the transmission carrier, each binary data signal is individually coded as a discrete symbol belonging to a PSK constellation of N symbols which are combined with N discrete points to produce two binary signal streams of which the first is in phase with the incoming signal while the second is in phase quadrature with said incoming signal. Each of said two binary signal streams is assigned its own signature by combining it with a discrete spreading code to produce two spread composite signal streams each of which is to be applied to a modulator. Both of said spreading codes are substantially orthogonally cross-correlated. The method may be used in a satellite communications system, in particular for digital sound transmission and communication via land microterminals.
Abstract:
A system for surveillance of a delimited area within which people move, wherein at least one hollow optical fiber is configured for extending through the area and is provided throughout its length with a plurality of holes that set an internal channel of the fiber in communication with the outside of the fiber itself. There is provided an optical source configured for supplying the optical signal to one end of the hollow optical fiber and a sensor designed to detect at one end of the hollow optical fiber the optical signal transmitted throughout the length of the fiber itself. A processing unit is configured for examining the spectrum of the optical signal detected by the sensors in order to detect the presence of toxic agents present in the area and drawn into said channel.
Abstract:
A communication system comprising a master control station and user terminals (100), in which synchronization in the outward link is achieved by transmitting a master code (MC) with the same clock frequency and carrier as the communication signals, wherein the master code (MC) is transmitted continuously and with greater power than that of the return link signals, and wherein the user voice activated message transmission carrier is broken during the pauses in a message. The invention relates in particular to a mobile satellite communications system.