Low power telemetry system and method

• US 20050030200A1
• Filed: 06/01/2004
• Published: 02/10/2005
• Est. Priority Date: 05/30/2003
• Status: Active Grant

• Current Assignee: General Dynamics Mission Systems Inc. (General Dynamics Corporation)
• Original Assignee: General Dynamics Advanced Information Systems Incorporated (General Dynamics Corporation)
• Inventors: Holt, Michael D.
• Granted Patent: US 7,970,003 B2
• Time in Patent Office: Days
• US Class Current: 340/870.70
• CPC Class Codes: H04Q 2209/30 using a wired architecture
• CPC Class Codes: H04Q 2209/756 where the polling of the sub-stations is cyclic, e.g. round-robin
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A telemetry system is described in which a plurality of channels are coupled to a bus. A control subsystem controls the channels so that one of the channels presents to the bus during its designated time period a channel characteristic. The control subsystem interrogates in the analog domain each of the channels during its designated time period, and forms a signal representative of the channel characteristic. The control subsystem may combine one or more of the signals into a digital packet, and transmit the same over a network.

Claims

1. A telemetry system comprising:

a bus;

a plurality of channels each coupled to the bus; and

a control subsystem for (1) controlling the channels so that each one presents to the bus, during a time period designated for the channel, a channel characteristic representative of a signal sampled by the channel, (2) interrogating in the analog domain, during the time period designated for a channel, the characteristic presented by the channel, and (3) forming a signal representative of the characteristic presented by the channel during the designated time period.

2. The system of claim 1 wherein the control subsystem time division multiplexes the channels so that each and only one channel presents to the bus a characteristic of the channel during a time period designated for the channel within a cycle.

3. The system of claim 1 wherein the control subsystem comprises a termination device at one end of the bus.

4. The system of claim 3 wherein the control subsystem further comprises a distributed control element at each of the channels.

5. The system of claim 1 wherein the channel characteristic presented by the channel is a channel impedance representative of the amplitude of a signal sampled by the channel.

6. The system of claim 5 wherein the control subsystem synchronizes the channels so that each one samples the amplitude of a signal at about the same time.

7. The system of claim 1 wherein the bus has one or more signal lines, and the control subsystem controls and provides power to each of the channels through the same one or more signal lines in the bus.

8. The system of claim 7 wherein the control subsystem controls and provides power to each of the channels through a differential signal transmitted over the same one or more signal lines.

9. The system of claim 8 wherein the one or more signal lines are implemented as a twisted pair.

10. The system of claim 8 wherein the differential signal has first and second states, and the differential signal provides power to the channel in the first state and performs a control function at the channel in the second state.

11. The system of claim 10 wherein a power storage element at the channel provides power to the channel when the differential signal is in the second state.

12. The system of claim 4 wherein the distributed control element in a channel identifies the time period designated for the channel within a cycle.

13. The system of claim 12 wherein the termination device clocks each of the distributed control elements through a clocking signal sent over the bus.

14. The system of claim 13 wherein each of the distributed control elements comprises a timing element which is updated responsive to the clocking signal, and the distributed control element identifies the time period designated for the channel based on a comparison of the timing element contents with a predetermined value for the channel.

15. The system of claim 14 wherein each distributed control element is programmable with the predetermined value for the channel

16. The system of claim 15 wherein each distributed control element is remotely programmable with the predetermined value for the channel.

17. The system of claim 3 wherein the termination device comprises a trunk interface.

18. The system of claim 3 wherein the termination device comprises a network interface.

19. The system of claim 18 wherein the network interface is a backbone network interface.

20. The system of claims 18 or 19 wherein the network interface comprises an internet interface.

21. The system of claim 20 wherein the network interface comprises an Internet interface.

22. The system of claim 14 wherein the distributed control element for one or more of the channels is implemented as a field programmable gate array (FPGA).

23. The system of claim 22 wherein the distributed control element for one or more of the channels is implemented as a complex programmable logic device (CPLD).

24. The system of claim 23 wherein the CPLD is a CMOS CPLD.

25. The system of claim 24 wherein the CMOS CPLD has a power consumption which varies directly with its clocking rate.

26. The system of claim 25 wherein the CMOS CPLD has about a zero power consumption at about a zero clocking rate.

27. The system of claim 5 wherein the control subsystem controls each of the channels to present to the bus an open circuit equivalent output impedance during time periods in the cycle other than the time period designated for the channel.

28. The system of claim 5 wherein each channel has a voltage controlled resistor circuit for presenting to the bus during the designated time period for the channel an impedance representative of the signal amplitude sampled by the channel.

29. The system of claim 5 wherein the impedance presented by a channel to the bus during the designated time period gives rise to an impedance mismatch condition at the channel.

30. The system of claim 29 wherein the control subsystem interrogates a channel during its designated time period by transmitting an analog pulse over the bus, and the impedance mismatch at the channel causes at least a partial reflection of the pulse to return to the termination device, with the amplitude of the reflected pulse being representative of the impedance presented by the channel.

31. The system of claim 30 wherein the control subsystem performs at least partial equalization of the transmitted pulses to compensate for variable attenuation caused by different distances between the termination device and each of the channels.

32. The system of claim 18 wherein the network interface is configured to combine the signals representative of the characteristic presented by one or more of the channels into a packet.

33. The system of claim 32 wherein the network interface is further configured to transmit the packet over a network.

34. The system of claim 18 wherein the network interface is configured to process the one or more signals using a procedure which may be programmed into the network interface.

35. The system of claim 34 wherein the procedure may be remotely programmed into the network interface.

36. The system of claim 34 wherein the procedure comprises a transformation applied to the one or more signals.

37. The system of claim 34 wherein the procedure comprises a feature extraction procedure.

38. The system of claim 34 wherein the procedure combines the one or more values into a beam.

39. The system of claim 34 wherein the procedure comprises a search procedure.

40. The system of claim 34 wherein the procedure comprises a predetermined schedule for interrogating the channels.

41. A method of telemetering one or more channels coupled to a bus comprising:

controlling the channels so that each one presents to the bus, during a time period designated for the channel, a channel characteristic representative of a signal sampled by the channel;

interrogating in the analog domain, during the time period designated for a channel, the characteristic presented by the channel; and

forming a signal representative of the characteristic presented by the channel during the designated time period.

42. The method of claim 41 further comprising time division multiplexing the channels so that each and only one channel presents to the bus a characteristic of the channel during a time period designated for the channel within a cycle.

43. The system of claim 41 wherein the channel characteristic presented by the channel is a channel impedance representative of the amplitude of a signal sampled by the channel.

44. The method of claim 43 further comprising synchronizing one or more of the channels so that the one or more channels sample the amplitude of a signal at about the same time.

45. The method of claim 41 wherein the bus has one or more signal lines, further comprising controlling and providing power to each of the channels through the same one or more signal lines in the bus.

46. The method of claim 45 further comprising controlling and providing power to each of the channels through a differential signal transmitted over the same one or more signal lines.

47. The method of claim 46 wherein the differential signal has first and second states, and the differential signal provides power to the channel in the first state and performs a control function at the channel in the second state.

48. The method of claim 47 wherein a power storage element at the channel provides power to the channel when the differential signal is in the second state.

49. The method of claim 41 further comprising identifying the time period designated for the channel within a cycle.

50. The method of claim 49 further comprising clocking a timing element at each of the channels through a clocking signal sent over the bus.

51. The method of claim 50 further comprising updating a timing element responsive to the clocking signal, and identifying the time period designated for the channel based on a comparison of the timing element contents with a predetermined value for the channel.

52. The method of claim 51 further comprising programming one or more of the channels with the predetermined value for the channel

53. The method of claim 52 further comprising remotely programming the one or more channels with the predetermined value for the channel.

54. The method of claim 43 further comprising controlling each of the channels to present to the bus an open circuit equivalent output impedance during time periods in the cycle other than the time period designated for the channel.

55. The method of claim 43 wherein the impedance presented by a channel to the bus during the designated time period gives rise to an impedance mismatch condition at the channel.

56. The method of claim 55 further comprising interrogating a channel during its designated time period by transmitting an analog pulse over the bus, and the impedance mismatch at the channel causes at least a partial reflection of the pulse to return to a termination device coupled to one end of the bus, with the amplitude of the reflected pulse being representative of the impedance presented by the channel.

57. The method of claim 56 further comprising performing at least partial equalization of the transmitted pulses to compensate for variable attenuation caused by different distances between the termination device and each of the channels.

58. The method of claim 41 further comprising combining the signals representative of the characteristic presented by one or more of the channels into a packet.

59. The method of claim 58 further comprising transmitting the packet over a network.

60. The method of claim 41 further comprising processing the one or more signals using a programmable procedure.

61. The method of claim 60 wherein the procedure is remotely programmable.

62. The method of claim 60 wherein the procedure comprises a transformation applied to the one or more signals.

63. The method of claim 60 wherein the procedure comprises a feature extraction procedure.

64. The method of claim 60 wherein the procedure combines the one or more values into a beam.

65. The method of claim 60 wherein the procedure comprises a search procedure.

66. The method of claim 60 wherein the procedure comprises a predetermined schedule for interrogating the channels.

67. A telemetry system comprising:

a bus;

a plurality of channels each coupled to the bus; and

means for (1) controlling the channels so that each one presents to the bus, during a time period within a cycle designated for the channel, a channel characteristic representative of a signal sampled by the channel, (2) interrogating in the analog domain, during the time period designated for a channel, the characteristic presented by the channel, and (3) forming a signal representative of the characteristic presented by the channel during the designated time period.

68. A termination device in a telemetry system comprising:

a controller;

a probe pulse driver and receiver circuit for interrogating in the analog domain one or more channels in the telemetry system; and

a power and control driver for transmitting to one or more channels in the telemetry system one or more power signals and one or more control signals.

69. The device of claim 68 wherein the controller is a microcontroller.

70. The device of claim 68 wherein the controller has one or more ingress signal lines for conveying program or program mode information to the controller.

71. The device of claim 70 wherein the program or program mode information is used to program the controller.

72. The device of claim 70 wherein the program or program mode information is used to program one or more of channels of the telemetry system.

73. The device of claim 68 wherein the controller has one or more egress signal lines for conveying packets to a network.

74. The device of claim 73 wherein the packet embodies information derived from one or more of the channels in the telemetry system.

75. The device of claim 68 wherein the probe pulse driver and receiver circuit has a receive side, and the device further comprises an A/D converter circuit coupled to the receive side of the probe pulse driver and receiver circuit.

76. The device of claim 68 wherein the probe pulse driver and receiver circuit interrogates in the analog domain one or more channels of the telemetry system through one or more differential mode signals transmitted and received over one or more twisted pair signal lines.

77. The device of claim 76 wherein the power and control driver circuit transmits the one or more power signals and the one or more control signals to the one or more channels of the telemetry system in the form of one or more differential mode signals transmitted over one or more twisted pair signal lines.

78. The device of claim 77 wherein the one or more twisted pair signal lines from the probe pulse driver and receiver circuit and the one or more twisted pair signal lines from the power and control driver circuit form a twisted quad.

79. The device of claim 77 wherein the one or more control signals and the one or more power signals are transmitted over the same one or more signal lines.

80. A channel in a telemetry system comprising:

a sample &

hold circuit for holding a sample of a signal;

a variable resistor circuit for presenting a variable impedance to one or more signal lines during a time period designated for the channel an impedance representative of the sample held by the sample &

hold circuit; and

a control element for controlling the variable resistor circuit to present to the one or more signal lines an open circuit equivalent impedance during times other than the time period designated for the channel.

81. The channel of claim 80 further comprising a switch which decouples the sample &

hold circuit from the variable resistor circuit during times other than the time period designated for the channel.

82. The channel of claim 80 wherein the control element is a programmable control element.

83. The channel of claim 82 wherein the control element is programmable with a unique channel identifier.

84. The channel of claim 83 wherein the control element includes a timing element which is updated responsive to a control signal.

85. The channel of claim 84 wherein the control element determines that the designated time period for the channel is occurring or will occur based on a comparison of the contents of the timing element with the unique channel identifier.

86. The channel of claim 85 wherein the control element is a zero power control element.