1. A rate matching circuit for adjusting the number of bits in a data block, the data block comprising a plurality of interleaved words generated by the action of an interleaving circuit on a coded output generated by the action of a coding circuit on a digital input, the coded output having a greater number of bits than the digital input, the rate matching circuit having means for adjusting the number of bits in the data block using a rate matching pattern to provide data bits for transmission during respective frames of a transmission channel, characterised in that means are provided for selecting the rate matching pattern depending on the characteristics of the coding circuit and of the interleaving circuit.
2. A rate matching circuit as claimed in claim 1, characterised in that the rate matching pattern is selected in such a way that all bits of the digital input can be derived from the remainder of the bits in successive interleaved blocks.
3. A rate matching circuit as claimed in claim 1 or 2, characterised in that the rate matching pattern for each interleaved word within the data block is offset with respect to the adjacent interleaved word or words within the block.
4. A rate matching circuit as claimed in any one of claims 1 to 3, characterised in that the rate matching pattern is selected as a function of the interleaving depth of the interleaving circuit.
5. A coding device comprising a rate matching circuit as claimed in any one of claims 1 to 4, further comprising an interleaving circuit and a coding circuit.
6. A decoding device comprising for decoding a signal coded by a coding device as claimed in claim 5, and comprising a data reconstruction circuit for reconstructing the interleaved words, a de-interleaving circuit and a channel decoder.
7. A communication system comprising a transmitter having a coding device as claimed in claim 5, and a receiver having a decoding device as claimed in claim 6.
8. A system as claimed in claim 7, comprising a plurality of coding devices, each for coding a respective digital input, and a multiplexer for combining output data words of the coding devices for subsequent transmission by the transmission system on a single transmission channel.
9. A system as claimed in claim 8, wherein the outputs of different coding devices are selected to have different data rates, the combined data rate corresponding to the channel capacity of the transmission channel.
10. A method of operating a rate matching circuit to adjust the number of bits in a data block, the data block comprising a plurality of interleaved words generated by the action of an interleaving circuit on a coded output generated by the action of a coding circuit on a digital input, the coded output having a greater number of bits than the digital input, the rate matching circuit adjusting the number of bits in the data block using a rate matching pattern to provide data bits for transmission during respective frames of a transmission channel, characterised by selecting the rate matching pattern depending on the characteristics of the coding circuit and of the interleaving circuit.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. In a partial stroke valve test apparatus having a housing enclosing a drive cam operably attached through a shaft to an actuator and an emergency shutdown valve, and an engagement cam attached to a cylindrical engagement shaft for selectively engaging with the drive cam during a partial stroke valve test and selectively rotated between a test position in which the engagement cam engages with the drive cam and an operational position in which the engagement cam is rotated away from the drive cam, the improvement comprising:
a detent radially communicating with the engagement shaft for selectively maintaining the partial stroke valve test apparatus in the test position or the operational position; and
a key for selectively rotating the drive cam, a key lock pin mounted in the housing, and a lock pin channel comprising a portion of the key wherein the key lock pin engages the lock pin channel, thereby preventing removal of the key from the valve test apparatus when the engagement cam is in the test position.
2. The partial stroke valve test apparatus of claim 1 and further comprising a safety release mechanism in communication with one of the engagement shaft and the engagement cam which can be selectively disengaged for rotation of the engagement cam between the test position and the operational position.
3. The partial stroke valve test apparatus of claim 2 wherein the safety release mechanism comprises a pin and a spring adapted to bias the pin toward the one of the engagement shaft and the engagement cam.
4. The partial stroke valve test apparatus of claim 3 wherein the one of the engagement shaft and the engagement cam comprises a seat adapted for seating of the pin therein.
5. The partial stroke valve test apparatus of claim 4 wherein the pin is adapted to be seated in the seat when the engagement cam is in the operational position.
6. The partial stroke valve test apparatus of claim 2 and further comprising a remote operator connected to the engagement shaft, a sensor adapted to generate information in response to the rotational position of the engagement shaft, and a controller for controlling the operation of the remote operator in response to the information generated by the sensor to selectively rotate the engagement cam between the test position and the operational position.
7. The partial stroke valve test apparatus of claim 1 wherein the detent comprises a detent pin and a spring adapted to bias the detent pin toward the engagement shaft.
8. The partial stroke valve test apparatus of claim 7 wherein the detent is located at an end of the engagement shaft.
9. The partial stroke valve test apparatus of claim 7 wherein the engagement shaft comprises at least one seat adapted for seating of the detent pin therein.
10. The partial stroke valve test apparatus of claim 9 wherein the at least one seat corresponds to one of the test position and the operational position.
11. The partial stroke valve test apparatus of claim 1 wherein the key comprises a flag for indicating that the engagement cam is in the test position.
12. The partial stroke valve test apparatus of claim 1 and further comprising a remote operator connected to the engagement shaft, a sensor adapted to generate information in response to the rotational position of the engagement shaft, and a controller for controlling the operation of the remote operator in response to the information generated by the sensor to selectively rotate the engagement cam between the test position and the operational position.
13. In a partial stroke valve test apparatus having a housing enclosing a drive cam operably attached through a shaft to an actuator and an emergency shutdown valve, and an engagement cam attached to an engagement shaft for selectively engaging with the drive cam during a partial stroke valve test and selectively rotated between a test position in which the engagement cam engages with the drive cam and an operational position in which the engagement cam is rotated away from the drive cam, the improvement comprising:
a safety release mechanism in communication with one of the engagement shaft and the engagement cam which can be selectively disengaged for rotation of the engagement cam between the test position and the operational position; and
a key for selectively rotating the drive cam, a key lock pin mounted in the housing, and a lock pin channel comprising a portion of the key wherein the key lock pin engages the lock pin channel thereby preventing removal of the key from the valve test apparatus when the engagement cam is in the test position.
14. The partial stroke valve test apparatus of claim 13 wherein the safety release mechanism comprises a pin and a spring adapted to bias the pin toward the one of the engagement shaft and the engagement cam.
15. The partial stroke valve test apparatus of claim 14 wherein the one of the engagement shaft and the engagement cam comprises a seat adapted for seating of the pin therein.
16. The partial stroke valve test apparatus of claim 15 wherein the pin is adapted to be seated in the seat when the engagement cam is in the operational position.
17. The partial stroke valve test apparatus of claim 13 wherein the key comprises a flag for indicating that the engagement cam is in the test position.
18. The partial stroke valve test apparatus of claim 17 and further comprising a remote operator connected to the engagement shaft, a sensor adapted to generate information in response to the rotational position of the engagement shaft, and a controller for controlling the operation of the remote operator in response to the information generated by the sensor to selectively rotate the engagement cam between the test position and the operational position.
19. In a partial stroke valve test apparatus having a housing enclosing a drive cam operably attached through a shaft to an actuator and an emergency shutdown valve, and an engagement cam attached to an engagement shaft for selectively engaging with the drive cam during a partial stroke valve test and selectively rotated between a test position in which the engagement cam engages with the drive cam and an operational position in which the engagement cam is rotated away from the drive cam, the improvement comprising:
a key for selectively rotating the drive cam, a key lock pin mounted in the housing, and a lock pin channel comprising a portion of the key wherein the key lock pin engages the lock pin channel thereby preventing removal of the key from the valve test apparatus when the engagement cam is in the test position.
20. The partial stroke valve test apparatus of claim 19 wherein the key comprises a flag for indicating that the engagement cam is in the test position.
21. The partial stroke valve test apparatus of claim 19 and further comprising a detent at an end of the engagement shaft for selectively maintaining the partial stroke valve test apparatus in the test position or the operational position, and a safety release mechanism in communication with one of the engagement shaft and the engagement cam which can be selectively disengaged for rotation of the engagement cam between the test position and the operational position.
22. The partial stroke valve test apparatus of claim 21 wherein the detent comprises a detent pin and a spring adapted to bias the pin toward the engagement shaft.
23. The partial stroke valve test apparatus of claim 22 wherein the detent is located at an end of the engagement shaft.
24. The partial stroke valve test apparatus of claim 22 wherein the engagement shaft comprises at least one seat adapted for seating of the detent pin therein.
25. The partial stroke valve test apparatus of claim 24 wherein the at least one seat corresponds to one of the test position and the operational position.
26. The partial stroke valve test apparatus of claim 21 wherein the safety release mechanism comprises a pin and a spring adapted to bias the pin toward the one of the engagement shaft and the engagement cam.
27. The partial stroke valve test apparatus of claim 26 wherein the one of the engagement shaft and the engagement cam comprises a seat adapted for seating of the pin therein.
28. The partial stroke valve test apparatus of claim 27 wherein the pin is adapted to be seated in the seat when the engagement cam is in the operational position.
29. The partial stroke valve test apparatus of claim 21 wherein the key comprises a flag for indicating that the engagement cam is in the test position.
30. In a partial stroke valve test apparatus having a housing enclosing a drive cam operably attached through a shaft to an actuator and an emergency shutdown valve, and an engagement cam attached to a cylindrical engagement shaft for selectively engaging with the drive cam during a partial stroke valve test and selectively rotated between a test position in which the engagement cam engages with the drive cam and an operational position in which the engagement cam is rotated away from the drive cam, the improvement comprising:
a remote operator connected to the engagement shaft, a sensor adapted to generate information in response to the rotational position of the engagement shaft, and a controller for controlling the operation of the remote operator in response to the information generated by the sensor to selectively rotate the engagement cam between the test position and the operational position;
a safety release mechanism in communication with one of the engagement shaft and the engagement cam which can be selectively disengaged for rotation of the engagement cam between the test position and the operational position;
wherein the safety release mechanism comprises a pin and a spring adapted to bias the pin toward the one of the engagement shaft and the engagement cam.
31. The partial stroke valve test apparatus of claim 30 wherein the one of the engagement shaft and the engagement cam comprises a seat adapted for seating of the pin therein.
32. The partial stroke valve test apparatus of claim 31 wherein the pin is adapted to be seated in the seat when the engagement cam is in the operational position.
33. In a partial stroke valve test apparatus having a housing enclosing a drive cam operably attached through a shaft to an actuator and an emergency shutdown valve, and an engagement cam attached to a cylindrical engagement shaft for selectively engaging with the drive cam during a partial stroke valve test and selectively rotated between a test position in which the engagement cam engages with the drive cam and an operational position in which the engagement cam is rotated away from the drive cam, the improvement comprising:
a remote operator connected to the engagement shaft, a sensor adapted to generate information in response to the rotational position of the engagement shaft, and a controller for controlling the operation of the remote operator in response to the information generated by the sensor to selectively rotate the engagement cam between the test position and the operational position; and
a detent at an end of the engagement shaft for selectively maintaining the partial stroke valve test apparatus in the test position or the operational position;
wherein the detent comprises a detent pin and a spring adapted to bias the detent pin toward the engagement shaft.
34. The partial stroke valve test apparatus of claim 33 wherein the detent is located at an end of the engagement shaft.
35. The partial stroke valve test apparatus of claim 33 wherein the engagement shaft comprises at least one seat adapted for seating of the detent pin therein.
36. The partial stroke valve test apparatus of claim 35 wherein the at least one seat corresponds to one of the test position and the operational position.