Abstract: There is disclosed a method of producing a soil remediant from liquid organic waste material in which the liquid organic waste material is concurrently pasteurised and digested by thermophilic aerobic digestion in the liquid phase in a single digester vessel. The organic waste material in the digester is maintained continuously at a temperature of at least 70° C. for at least an hour and the liquid organic waste material comprises at least 70% water and can be pumped. After a period of at least an hour a small amount of pasteurised organic waste material is removed and a corresponding amount of fresh organic waste material is added to the single digester vessel such that the temperature is maintained in a comfort zone of the thermophilic bacteria. In a preferred embodiment the thermophilic aerobic digestion is facilitated by micro-organisms including crenarchaeota. The liquid organic waste material can be combined with a microporous adsorbent.

Abstract: There is disclosed a method of producing a soil remediant from liquid organic waste material in which the liquid organic waste material is concurrently pasteurised and digested by thermophilic aerobic digestion in the liquid phase in a single digester vessel. The organic waste material in the digester is maintained continuously at a temperature of at least 70° C. for at least an hour and the—liquid organic waste material comprises at least 70% water and can be pumped. After a period of at least an hour a small amount of pasteurised organic waste material is removed and a corresponding amount of fresh organic waste material is added to the single digester vessel such that the temperature is maintained in a comfort zone of the thermophilic bacteria. In a preferred embodiment the thermophilic aerobic digestion is facilitated by micro-organisms including crenarchaeota. The liquid organic waste material can be combined with a microporous adsorbent.

Abstract: A continuous wave radar system, for example a radar altimeter, comprises a memory (24) for storing an array of return signals, means for performing a time integration (25) of the array to improve its signal-to-noise ratio, means responsive to the time integrated array (26) to compare (30) the noise level (28) thereof with the peak level (27) thereof to obtain the signal-to-noise ratio of the array, and control means (31) responsive to the signal-to-noise ratio thus obtained to set either the period over which the said time integration is performed for each renewal of the time integrated array (26), or the power of the transmitted signal, of both, in accordance with predetermined criteria to the minimum necessary to ensure an adequate signal-to-noise ratio.

Abstract: A communications system includes a plurality of interfaces (20) each of which can receive and/or transmit data to a common transmission network (21). Each interface (20) transmitting data to the network (21) attaches a classification code to the transmitted data, and each interface (20) receiving data from the network (21) retrieves the classification code and restricts access to the associated data in dependence upon that classification code. The invention alleviates the need to employ "secure" and "clear" communications networks in parallel, and is especially applicable to aircraft communications.

Abstract: The invention provides a system and method whereby a mobile station of telecommunications system selects one of a number of fixed ground stations by which the mobile station communicates with the public switched telephone network or other such system, selection being made by the mobile station receiving selected criteria and deriving from a plurality of these criteria a score for each of a plurality of the fixed stations, the fixed station via which communication is to be made being selected in dependence upon the score derived for that fixed station.

Abstract: A continuous wave radar altimeter comprises a memory (24, 26), means for storing in the memory in digital form an array of return signals representative of the variation of reflected amplitude with path length, means (27), for addressing the memory for identifying a peak return representative of the highest objects on the terrain, means (28) responsive to the array for determining the signal-to-noise ratio thereof, and means (29) responsive to the height at which the said peak return occurs and to the signal-to-noise ratio to determine a "center of area" height representative of the lowest surface on the terrain. The altimeter thus provides not only the peak level, representing for example the tops of trees and buildings, but also the ground level.