Abstract: A closure assembly for terminating an end of a pipe (4) has an end-cap (4) holding and having fluid-tight connection to a mutually coaxial cylindrical plug (2) and circular collar (3). The plug (2) and the collar (3) are configurable between respective engaged and disengaged configurations and mutually spaced to provide an annular space therebetween when the plug (2) and collar (3) are in their disengaged configurations. The annular space is arranged to receive an end of a pipe (1) arranged coaxially with the plug (2) and collar (3), the plug (2) and collar (3) being respectively slidable into and over the end of the pipe (1). The plug (2), when in its engaged configuration, grips the inner face of said pipe (41) and to provide a fluid tight seal and the collar (3), when in its engaged configuration, grips the outer face of the pipe (1) and to provide a fluid tight seal.

Abstract: A boring apparatus, such as a drilling apparatus for forming holes in pressurized pipes, comprises a cutting head (5) mounted to a distal end of a boring bar (2) which is itself connected to a feed screw (3) by a feed nut so that relative rotation between the boring bar (2) and the feed screw (3) cause the cutting head (5) and boring bar (2) to traverse axially along the feed screw (3) while the cutting head (5) is rotated for cutting. The apparatus has a main drive motor arranged to drive the cutting head (5), boring bar (2) and a main drive shaft (4). The main drive shaft (4) and the feed screw (3) are operably connected at the proximal end through a pair of adjacent coaxial planetary gear assemblie (6) whose planetary gear carriers are liked to rotate in unison about the axis.

Abstract: A boring apparatus, such as a drilling apparatus for forming holes in pressurised pipes, comprises a cutting head (5) mounted to a distal end of a boring bar (2) which is itself connected to a feed screw (3) by a feed nut so that relative rotation between the boring bar (2) and the feed screw (3) cause the cutting head (5) and boring bar (2) to traverse axially along the feed screw (3) whilst the cutting head (5) is rotated for cutting. The apparatus has a main drive motor arranged to drive the cutting head (5), boring bar (2) and a main drive shaft (4). The main drive shaft (4) and the feed screw (3) are operably connected at the proximal end through a pair of adjacent coaxial planetary gear assemblie (6) whose planetary gear carriers are liked to rotate in unison about the axis.

Abstract: A closure assembly for terminating an end of a pipe (4) has an end-cap (4) holding and having fluid-tight connection to a mutually coaxial cylindrical plug (2) and circular collar (3). The plug (2) and the collar (3) are configurable between respective engaged and disengaged configurations and mutually spaced to provide an annular space therebetween when the plug (2) and collar (3) are in their disengaged configurations. The annular space is arranged to receive an end of a pipe (1) arranged coaxially with the plug (2) and collar (3), the plug (2) and collar (3) being respectively slidable into and over the end of the pipe (1). The plug (2), when in its engaged configuration, grips the inner face of said pipe (41) and to provide a fluid tight seal and the collar (3), when in its engaged configuration, grips the outer face of the pipe (1) and to provide a fluid tight seal.

Abstract: A channel estimation method for a digital telecommunication station is disclosed. A frequency correction burst is sought by scanning of the wanted channel. The frequency correction burst is used to provide coarse time and frequency synchronizations. A synchronization burst is received. Calculating the cross-correlation of the expected training sequence with the training sequence contained in said synchronous burst to obtain a channel estimate. A frequency error estimate is derived from the channel estimate, and the frequency error of the received burst is corrected in accordance with said frequency error estimate. The received synchronous burst is equalized. The frequency corrected symbols are used to refine the time and frequency synchronizations.

Abstract: A received frame is provided to a first decoder and a first time reverse unit. The first decoder decodes the provided frame and outputs the decoded frame. The first time reverse unit reverses bits of the provided frame in time direction and outputs the time reversed frame. The time reversed frame is provided to a second decoder. The second decoder decodes the time reversed frame. This decoded frame is then provided to a second time reverse unit. The second time reverse unit reverses bits of the decoded frame in time direction and outputs the frame. The frame is outputted from the first decoder is compared with the frame is outputted from the second time reverse unit by comparator. If any difference exist between the two frames then the received frame is judged as unreliable.

Abstract: A method of improving frame erasure performance, in particular for slow frequency hopping channels with cyclic co-channel interference, by selection of the most suitable PBER threshold from a range of PBER thresholds. A burst quality metric is assigned to each burst in a frame and the bursts are then ranked in the order of the values of the assigned quality metrics. The differences in the metrics between successive bursts in the ranked order are measured. The position in the ranked order of the largest difference between bursts (dMAX) is used in the selection of the most suitable PBER threshold.

Abstract: A method of improving frame erasure performance for slow frequency hopping channels utilizing two convolutional decoding steps and two PBER thresholds in conjunction with the cyclic redundancy check. The breakdown condition in the convolutional decoding process is detected by means of a ‘forward backward decoding’ algorithm. The breakdown condition is detected with two passes of the convolutional decoder. When the decoder breaks down an essentially random burst of erroneous decoded bits are produced, and due to the memory effect of the decoder these will be different in each decoding direction. These erroneous random errors may be detected by comparison of the two decoded sets of data.