Abstract: The invention provides for apparatus (10) for lifting a conveyor belt (13) supported on a series of idler rollers (19) on a belt conveyor (11), the apparatus (10) comprising a body (4) selectively movable along the belt conveyor (11) and a belt lifting assembly (50) mounted on the body (41) and operable to engage the conveyor belt (13) to lift the belt from, and subsequently lower said belt onto, an idler roller operatively supporting the belt on the conveyor (11).

Abstract: The invention provides for apparatus (10) for lifting a conveyor belt (13) supported on a series of idler rollers (19) on a belt conveyor (11), the apparatus (10) comprising a body (4) selectively movable along the belt conveyor (11) and a belt lifting assembly (50) mounted on the body (41) and operable to engage the conveyor belt (13) to lift the belt from, and subsequently lower said belt onto, an idler roller operatively supporting the belt on the conveyor (11).

Abstract: In a communications between a base station and subscriber unit in time slots within fixed length time frames, different types of messages require different numbers of timeslots per frame to maintain transmission rate. At least a portion of the message is detected to determine the type of message, and if appropriate, additional time slot(s) are assigned.

Abstract: In transmission between a base station and a subscriber unit, system control signals are sent in time slots within fixed length time frames. The system control signals are fragmented, each fragment being sent in a different time slot of a frame.

Abstract: The present invention relates to a method of transmitting digital data messages in predetermined time slots within fixed length time frames from at least one of a plurality of subscriber units to a base station for reception, in which, selectively, subscriber units which are members of one or more predetermined classes of subscriber units are restricted from transmitting at least one predetermined type of message. This advantageously helps in avoiding overload of the network. The invention also relates to corresponding communication means.

Abstract: In a communications network involving transmission of data packets, control messages between nodes are assigned priorities dependent on message type. The allocated of messages to TDM/TDMA time slots is dependent on the assignment priorities.

Abstract: In time domain multiplex/time domain multiple access communications between a base station and subscriber unit, the base station sends a timing reference signal. A subscriber unit responds with a data packet (a) sufficiently short to ensure correct reception by the base irrespective of transmission time. The base determines the transmission time taken and instructs the subscriber unit to advance its timings so that longer data packets (b) can be sent so as to be received when expected. The timing adjustment includes both a fixed present component dependent on approximate separation of base station and subscriber unit, and a second component from measurement of the transmission time taken.

Abstract: A radio based communication system comprises a base station (1) and one or more remote stations (2) each incorporating a radio transmitter and receiver to support communication between the base station and each remote station on a down link and between each remote station and the base station on an up link. Each link comprises a plurality of frames of fixed length divided into a fixed number of slots. The base station includes a base control which transmits control data in a general control slot (GC) in each frame of the down link so as to identify to each remote station a down-setup slot (DSU) in each frame of the down link in which the base station (1) is to announce the transmission of data for it and identify at least one down-transfer slot (DTR) in the frame of the down link in which the data is to be transmitted. The control data further identifies an acknowledgement slot (ACK) in each frame of the down link and an up-setup slot (USU) divided into sub-slots (1/4) in each frame of the up link.