1. A laser scanner having
a first axis;
a second axis extending essentially transversely to said first axis;
a measuring head adapted to be rotated about said first axis, said measuring head having at least a first, a second, and a third module, wherein at least said first module and said third module are releasably connected to each other;
a first rotary drive for rotating said measuring head, said first rotary drive being comprised within said first and said second modules;
a rotary mirror adapted to be rotated about said second axis, said rotary mirror being comprised within said third module;
a second rotary drive for rotating said rotary mirror, said second drive being likewise comprised within said third module;
a transmitter arranged in said measuring head for transmitting a light beam;
a receiver arranged in said measuring head for receiving said light beam after a reflection thereof by an object located at a distance from said laser scanner;
a computer arranged in said measuring head for processing signals embedded within said received light beam.
2. The laser scanner of claim 1, wherein said first rotary drive comprises a base, a rotor rotatable relative to said base, and a drive motor for rotating said rotor, said base together with said rotor being comprised within said first module and said drive motor being comprised within said second module.
3. The laser scanner of claim 1, wherein said first module is arranged centrally and at a lower side of said measuring head, said second module being arranged laterally and likewise at said lower side of said measuring head.
4. The laser scanner of claim 2, wherein said rotor has at least one leg with at least one further module being adapted to be attached thereto.
5. The laser scanner of claim 4, wherein said leg is configured integral with said rotor.
6. The laser scanner of claim 4, wherein said rotor has two legs, said legs extending parallel to each other and parallel to said first axis.
7. The laser scanner of claim 6, wherein said legs delimit a gap between them.
8. The laser scanner of claim 7, wherein said gap is dimensioned such as to receive said rotary mirror.
9. The laser scanner of claim 7, wherein an optical reference mark is situated within said rotor between said legs.
10. The laser scanner of claim 2, wherein said base has standardized pegs, adjustable feet and a bubble level.
11. The laser scanner of claim 2, wherein said second module, further, comprises an inclination sensor.
12. The laser scanner of claim 11, wherein said third module is arranged laterally and at an upper side of said measuring head.
13. The laser scanner of claim 6, wherein said rotor has two legs, said legs extending parallel to each other and parallel to said first axis, said third module being attached to one of said legs.
14. The laser scanner of claim 13, wherein said rotary mirror extends through a form-fitting opening within said leg.
15. The laser scanner of claim 1, wherein said receiver is comprised within a fourth module.
16. The laser scanner of claim 15, wherein said fourth module is arranged laterally and at an upper side of said measuring head.
17. The laser scanner of claim 1, wherein said receiver comprises a range finder.
18. The laser scanner of claim 1, wherein said transmitter is comprised within said third module.
19. The laser scanner of claim 1, wherein said computer is comprised within a fifth module.
20. The laser scanner of claim 1, wherein said computer comprises a control panel.
21. The laser scanner of claim 19, wherein said fifth module is arranged laterally and at a lower side of said measuring head.
22. The laser scanner of claim 15, wherein said third and said fourth module are arranged on opposite sides of said first module.
23. The laser scanner of claim 19, wherein said second and said fifth module are arranged on opposite sides of said first module.
24. The laser scanner of claim 1, wherein said first and said third modules are mechanically interconnected by means of form fitting mechanical connectors.
25. The laser scanner of claim 15, wherein said first and said fourth modules are mechanically interconnected by means of form fitting mechanical connectors.
26. The laser scanner of claim 19, wherein said first and said fifth modules are mechanically interconnected by means of form fitting mechanical connectors.
27. The laser scanner of claim 1, wherein said first and said second modules are configured integral with each other.
28. The laser scanner of claim 1, wherein said first and third modules are electrically interconnected by means of a CAN bus.
29. The laser scanner of claim 15, wherein said first, third and fourth modules are electrically interconnected by means of a CAN bus.
30. The laser scanner of claim 19, wherein said first, third and fifth modules are electrically interconnected by means of a CAN bus.
31. The laser scanner of claim 1, wherein said first axis extends vertically under normal operational conditions of said laser scanner.
32. The laser scanner of claim 1, wherein said second axis extends horizontally under normal operational conditions of said laser scanner.
33. The laser scanner of claim 2, wherein said base is held stationary under normal operational conditions of said laser scanner.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. A method for controlling a buffer level in a communication system, said method comprising the steps of:
computing a predicted number of encoded frames in said buffer; and
ensuring said predicted number of encoded frames does not exceed a maximum number of encoded frames.
2. The method of claim 1, wherein said communication system is a digital audio broadcasting (DAB) system.
3. The method of claim 1, wherein said communication system employs perceptual audio coding.
4. The method of claim 1, wherein said communication system is a multiple channel communication system and wherein said method further comprises the step of maintaining an approximately equal frame rate for each of said channels.
5. The method of claim 1, wherein step of computing said predicted number of encoded frames predicts said number of encoded frames in an encoder buffer.
6. The method of claim 1, wherein step of computing said predicted number of encoded frames predicts said number of encoded frames in a decoder buffer.
7. The method of claim 1, wherein said step of computing said predicted number of encoded frames considers a respective data rate of an encoder and a decoder and a channel bit rate of said communication system.
8. The method of claim 1, wherein said step of computing said predicted number of encoded frames is performed by a rate controller and wherein said buffer is a decoder buffer.
9. The method of claim 1, wherein said predicted number of frames is computed as follows:
FpredFdec0(FencFenc0)
where Fdec0 is a desired decoder buffer level, Fenc is a number of frames in an encoder buffer and Fenc0 is a desired encoder buffer level.
10. The method of claim 1, further comprising the step of receiving an indication of a number of frames in an encoder buffer and wherein step of computing said predicted number of encoded frames predicts said number of encoded frames in a decoder buffer based on said number of frames in an encoder buffer.
11. The method of claim 1, wherein said ensuring step further comprises the step of allocating an additional number of bits to each frame if said buffer level becomes too high.
12. The method of claim 1, wherein said ensuring step further comprises the step of transmitting waste bits if said buffer level becomes too high.
13. The method of claim 1, wherein said ensuring step further comprises the step of allocating a fewer number of bits to each frame if said buffer level becomes too low.
14. The method of claim 1, wherein said ensuring step further comprises the step of transmitting empty packets if said buffer level becomes too low.
15. A method for controlling a buffer in a communication system, said method comprising the steps of:
computing a predicted number of encoded frames in said buffer; and
transmitting said predicted number of encoded frames to a receiver.
16. The method of claim 15, wherein said communication system is a digital audio broadcasting (DAB) system.
17. The method of claim 15, wherein step of computing said predicted number of encoded frames predicts said number of encoded frames in a decoder buffer.
18. The method of claim 15, wherein said step of computing said predicted number of encoded frames considers a respective data rate of an encoder and a decoder and a channel bit rate of said communication system.
19. The method of claim 15, wherein said step of computing said predicted number of encoded frames is performed by a rate controller and wherein said buffer is a decoder buffer.
20. The method of claim 15, wherein said transmitting step further comprises the step of quantizing said predicted number of encoded frames before transmission to a receiver.
21. A method for controlling a buffer in a communication system, said method comprising the steps of:
receiving a predicted number of encoded frames in said buffer; and
using said predicted number of encoded frames to determine when to commence a decoding of said frames.
22. The method of claim 21, further comprising the step of determining when to decode said frames after a decoder is first started using said predicted number of encoded frames.
23. The method of claim 21, further comprising the step of determining when to decode said frames after a new program is selected using said predicted number of encoded frames.
24. The method of claim 21, wherein said communication system is a digital audio broadcasting (DAB) system.
25. The method of claim 21, wherein said predicted number of encoded frames indicates a number of encoded frames in a decoder buffer.
26. The method of claim 21, wherein said predicted number of encoded frames considers a respective data rate of an encoder and a decoder and a channel bit rate of said communication system.
27. The method of claim 21, wherein said predicted number of encoded frames is determined by an encoder and wherein said buffer is a decoder buffer.
28. A method for synchronizing a receiver and a transmitter in a communication system, said method comprising the steps of:
receiving a predicted number of encoded frames in a buffer;
comparing said predicted number of encoded frames to an actual number of encoded frames in said buffer; and
adjusting a clock frequency based on said comparison.
29. The method of claim 28, wherein said communication system is a digital audio broadcasting (DAB) system.
30. The method of claim 28, wherein predicted number of encoded frames indicates number of encoded frames in a decoder buffer.
31. The method of claim 28, wherein said predicted number of encoded frames considers a respective data rate of an encoder and a decoder and a channel bit rate of said communication system.
32. The method of claim 28, wherein said predicted number of encoded frames is determined by an encoder and wherein said buffer is a decoder buffer.
33. The method of claim 28, wherein said adjusting step increases said clock frequency if said predicted number of encoded frames is lower than said actual number of encoded frames in said buffer.
34. The method of claim 28, wherein said adjusting step decreases said clock frequency if said predicted number of encoded frames is higher than said actual number of encoded frames in said buffer.
35. A system for controlling a buffer level in a communication system, comprising:
a memory that stores computer-readable code; and
a processor operatively coupled to said memory, said processor configured to implement said computer-readable code, said computer-readable code configured to:
compute a predicted number of encoded frames in said buffer; and
ensure said predicted number of encoded frames does not exceed a maximum number of encoded frames.
36. The system of claim 35, wherein said processor is further configured to transmit said predicted number of encoded frames to a receiver.
37. A system for controlling a buffer level in a communication system, comprising:
a memory that stores computer-readable code; and
a processor operatively coupled to said memory, said processor configured to implement said computer-readable code, said computer-readable code configured to:
receive a predicted number of encoded frames in a buffer; and
compare said predicted number of encoded frames to an actual number of encoded frames in said buffer.
38. The system of claim 37, wherein said processor is further configured to adjust a clock frequency based on said comparison.
39. The system of claim 38, wherein said processor is further configured to increase said clock frequency if said predicted number of encoded frames is lower than said actual number of encoded frames in said buffer.
40. The system of claim 38, wherein said processor is further configured to decrease said clock frequency if said predicted number of encoded frames is higher than said actual number of encoded frames in said buffer.
41. The system of claim 37, wherein said processor is further configured to determine when to commence a decoding of said frames using said predicted number of encoded frames.
42. The system of claim 41, wherein said processor waits approximately said predicted number of encoded frames before decoding said frames after a decoder is first started.
43. The system of claim 41, wherein said processor waits approximately said predicted number of encoded frames before decoding said frames after a new program is selected.
44. The system of claim 37, wherein said communication system is a digital audio broadcasting (DAB) system.
45. A system for controlling a buffer level in a communication system, comprising:
a buffer for storing frames of encoded data; and
means for computing a predicted number of encoded frames in said buffer; and
means for ensuring said predicted number of encoded frames does not exceed a maximum number of encoded frames.
46. A system for controlling a buffer level in a communication system, comprising:
a buffer for storing frames of encoded data; and
an input port for receiving a predicted number of encoded frames in a buffer; and
means for comparing said predicted number of encoded frames to an actual number of encoded frames in said buffer.
47. The system of claim 46, further comprising means for adjusting a clock frequency based on said comparison.
48. The system of claim 46, further comprising means for waiting until said buffer contains approximately said predicted number of encoded frames before decoding said frames.