Voice-activated personal alarm

• US 20020021231A1
• Filed: 12/01/2000
• Published: 02/21/2002
• Est. Priority Date: 07/06/1998
• Status: Active Grant

• Current Assignee: MOSAID Technologies Inc. (f/k/a Conversant Intellectual Property Management)
• Original Assignee: Dan Schlager, William B. Baringer
• Inventors: Baringer, William B., Schlager, Dan
• Granted Patent: US 6,518,889 B2
• Time in Patent Office: Days
• US Class Current: 340/984
• CPC Class Codes: B63C 9/0005 by means of alarm devices for persons falling into the water, e.g. by signalling, by controlling the propulsion or manoeuvring means of the boat alarms responsive to presence of persons in a body of water in general G08B21/08
• CPC Class Codes: G01S 19/17 Emergency applications
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 5/01 Determining conditions which influence positioning, e.g. radio environment, state of motion or energy consumption
• CPC Class Codes: G08B 1/08 using electric transmission ; transformation of alarm signals to electrical signals from a different medium, e.g. transmission of an electric alarm signal upon detection of an audible alarm signal
• CPC Class Codes: G08B 13/1427 with transmitter-receiver for distance detection
• CPC Class Codes: G08B 21/0211 Combination with medical sensor, e.g. for measuring heart rate, temperature
• CPC Class Codes: G08B 21/0222 Message structure or message content, e.g. message protocol
• CPC Class Codes: G08B 21/0227 System arrangements with a plurality of child units
• CPC Class Codes: G08B 21/023 Power management, e.g. system sleep and wake up provisions
• CPC Class Codes: G08B 21/0247 System arrangements wherein the alarm criteria uses signal strength
• CPC Class Codes: G08B 21/0269 System arrangements wherein the object is to detect the exact location of child or item using a navigation satellite system, e.g. GPS
• CPC Class Codes: G08B 21/028 Communication between parent and child units via remote transmission means, e.g. satellite network
• CPC Class Codes: G08B 21/0283 via a telephone network, e.g. cellular GSM
• CPC Class Codes: G08B 21/0286 Tampering or removal detection of the child unit from child or article
• CPC Class Codes: G08B 21/0288 Attachment of child unit to child/article
• CPC Class Codes: G08B 21/0294 Display details on parent unit
• CPC Class Codes: G08B 21/088 by monitoring a device worn by the person, e.g. a bracelet attached to the swimmer
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]

Abstract

A self-locating remote monitoring system (750) includes a supervising base station (754) and one or more remote monitoring units (752). A remote unit (752) includes a navigational receiver (756) operating with an existing navigational system for providing a remote unit location (759) and includes a transmitter (758) for communicating the location (759) to the base station (754) for display (772). The remote unit (752) includes one or more physiological/environmental sensors (760) for monitoring at the remote location. In a specific embodiment a change in sensor status (761) results in the status and the location being transmitted to the base station (754). The base station (754) includes alarms (776) and displays (772) responsive to the change in status. One embodiment defines a man-over-board system (300) which combines water immersion (308) and distance (334) from the base station (318) to trigger an alarm (332) and begin location tracking (324). Another embodiment defines an invisible fence system (1020) which uses location (1035) and time (1039) to define boundaries for containment and exclusion. Another embodiment includes a weather surveillance radar receiver (1188) providing weather parameters (1189) within a weather region (1193) and defines a remote weather alarm system (1180). The weather alarm system (1180) uses the weather receiver (1188) to monitor weather within a defined region (1193) and to provide the base station (1184) with location (1187) and weather parameters (1199) if the parameters fall outside defined limits (1195).

Claims

1. A man-over-board alarm system, comprising:

a remote unit including a navigational receiver for receiving navigational information defining a location of the remote unit, and a radio transmitter for transmitting the remote unit location;

a base station including a radio receiver for receiving the remote unit location;

the remote unit and the base station defining a separation distance between the remote unit and the base station;

the base station including measuring means for determining whether the separation distance exceeds a predetermined limit, and means responsive to the measuring means for giving an alarm and a display for displaying the remote unit location,

whereby, a separation distance exceeding the predetermined limit causes a man-over-board alarm and the base station displays the location of the remote unit.

2. The man-over-board alarm system as set forth in claim 1, wherein the remote unit further includes a sensor having an output signal, the sensor defining a sensor status, and the radio transmitter connected to the output signal for transmitting the sensor status, and the base station includes a display for displaying the sensor status, the navigational receiver further includes a low power standby mode and a normal operating mode, and the alarm system further includes means responsive to the sensor output signal for causing the navigational receiver to switch from the standby mode to the normal operating mode when a hazard is detected.

3. The man-over-board alarm system as set forth in claim 1, wherein the remote unit further includes a sensor having an output signal, the sensor defining a sensor status, and the radio transmitter connected to the output signal for transmitting the sensor status, and the base station includes a display for displaying the sensor status, the remote unit further includes a beacon activated by the sensor output signal when a hazard is detected.

4. The man-over-board alarm system as set forth in claim 1, wherein the remote unit further includes a sensor having an output signal, the sensor defining a sensor status, and the radio transmitter connected to the output signal for transmitting the sensor status, and the base station includes a display for displaying the sensor status, and means responsive to the sensor status for giving an alarm.

5. The man-over-board alarm system as set forth in claim 1, wherein the remote unit further includes a sensor having an output signal, the sensor defining a sensor status, and the radio transmitter connected to the output signal for transmitting the sensor status, and the base station includes a display for displaying the sensor status, the sensor output signal is provided by a remote unit manually operated switch, defining a panic button, and the system includes a beacon activated by the panic button.

6. The man-over-board alarm system as set forth in claim 1, including a one-way voice channel linking the remote unit with the base station.

7. The man-over-board alarm system as set forth in claim 1, wherein the base station includes a radio transmitter and the remote unit includes a radio receiver defining two-way radio communication between the remote unit and the base station, including a two-way voice channel linking the remote unit and the base station.

8. An invisible fence system for monitoring a movable subject, comprising:

a remote unit including,

a navigational receiver providing a remote unit location,

means for providing time-of-day, and

a radio transmitter;

a base station including,

receiving means defining a one-way communication link with the remote unit,

and

an alarm;

the remote unit further including,

a first memory for storing information defining a geographic region,

a second memory storing information defining a predetermined positional status and a predetermined time interval, and further defining a curfew, and

a circuit for comparing the remote unit location, the defined geographic zone, the predetermined positional status, the time-of-day and the curfew, and defining a positional and time status, and

the circuit connected to the transmitter for communicating the positional and time status;

the base station being responsive to the communicated positional and time status and defining a curfew violation, and

the alarm being responsive to the curfew violation.

9. The invisible fence system as set forth in claim 8, wherein the remote unit transmits the remote unit location and the time-of-day, and the base station further includes means for displaying the remote unit location and the time-of-day.

10. The invisible fence system as set forth in claim 8, wherein the communications link between the remote unit and the base station receiving means includes a modem for connection to a communications network, the network providing a portion of the completed communications link.

11. An invisible fence system, comprising:

a remote unit including,

a navigational receiver providing a remote unit location and a time-of-day,

a radio transmitter connected for transmitting the remote unit location and the time-of-day,

a radio receiver,

alarm and enforcement means responsive to the radio receiver;

a base station including,

means for receiving the remote unit location and the time-of-day,

a first memory storing information defining a geographical region,

a second memory storing information defining a predetermined positional status and a time curfew,

a circuit for comparing the remote unit location, the defined geographical region and the predetermined positional status, and the time-of-day and the time curfew and for providing a positional and curfew status,

a control circuit responsive to the positional and curfew status and defining an enforcement command, and

means for transmitting the enforcement command; and

the remote unit alarm and enforcement means being responsive to the transmitted enforcement command.

12. The invisible fence system as set forth in claim 11, wherein the base station further includes means for displaying the remote unit location and the time-of-day, and an alarm responsive to an enforcement command.

19. The personal alarm system as set forth in claim 18, wherein the received signal strength is further defined by a voltage level on a signal line and the control means includes an analog-to-digital converter connected to receive the signal line and to provide digital output signals connected to address input lines of a read-only memory, the memory containing information defining the power-level function, the memory having digital output lines connected for controlling the power level in response to the received signal strength.

20. The personal alarm system as set forth in claim 18, wherein the received signal strength is further defined by a voltage level on a signal line and the control means includes an analog-to-digital converter connected to receive the signal line and to provide digital output signals connected to address input lines of a read-only memory, the memory containing information defining the power-level function, the memory having digital output lines connected to the inputs of a digital-to-analog converter, the digital-to-analog converter having an analog output line providing a control voltage for selecting the remote unit transmission power level.

13. A stationary environmental monitor system, comprising:

a remote unit including,

storage means for storing information defining the location of the remote unit,

an environmental sensor providing a plurality of output signals defining a sensor status vector, an output signal and defining a sensor status, and

a radio transmitter connected for transmission of the location defining information and the sensor status; and

a base station including,

a radio receiver for receiving the location defining information and the sensor status, and

means responsive to a predetermined change in the sensor status for displaying the location of the remote unit and for providing an alarm,

whereby the location of the remote unit is stored in the storage means and a predetermined change in the sensor status causes the location to be displayed and an alarm to be given at the base station.

14. A personal alarm system, comprising:

a remote unit including a navigational receiver for receiving navigational information, a demodulator for demodulating the received navigational information, timing circuits for providing precise time-of-day information, a manually operated switch, defining a panic button and having an output signal defining a switch status, operation of the panic button producing a change in the switch status, and a radio transmitter for transmitting the demodulated navigational information, the precise time-of-day information, and the switch status;

a base station including a radio receiver for receiving the demodulated navigational information, the precise time-of-day information, and the switch status;

the base station also including computational means connected for combining the received demodulated navigational information and the precise time-of-day information to determine a location of the remote unit, and a display for displaying the location of the remote unit; and

the base station also including means for displaying the switch status and means responsive to a change in the switch status for giving an alarm,

whereby, the remote unit location is displayed, and the alarm is responsive to the panic button.

15. A personal alarm system, comprising:

a remote unit including a navigational receiver for receiving navigational information defining a location of the remote unit, a manually operated switch defining a panic button and having an output signal defining a switch status, operation of the panic button producing a change in the switch status, and a radio transmitter for transmitting the remote unit location and the switch status;

a base station including a radio receiver for receiving the remote unit location and the switch status;

the base station also including a display for displaying the remote unit location and the switch status; and

the base station also including means responsive to a change in the switch status for giving an alarm,

whereby, the remote unit location is displayed and a change in the switch status produces an alarm.

16. A personal alarm system, comprising:

a remote unit including a navigational receiver for receiving navigational information defining a location of the remote unit, the navigational receiver having a low power standby mode and a normal operating mode, the remote unit also including a sensor for detecting a personal hazard, the sensor having an output signal and defining a sensor status, means responsive to the sensor output signal for causing the navigational receiver to switch from the standby mode to the normal operating mode when a hazard is detected, and a radio transmitter for transmitting the remote unit location and the sensor status;

a base station including a radio receiver for receiving the remote unit location and the sensor status;

the base station also including a display for displaying the remote unit location and the sensor status; and

the base station also including means responsive to a change in the sensor status for giving an alarm,

whereby, the remote unit location is displayed and a change in the sensor status produces an alarm.

17. A personal alarm system, comprising:

a remote unit including radio transmitting means, radio receiving means, at least one sensor means for detecting a personal hazard, the remote unit transmitting means responsive for communicating a detected hazard;

the remote unit transmitting means being able to transmit at more than one power level and defining a higher power level, and the remote unit including means for enabling transmission at the higher power level when a personal hazard is detected;

a base station including radio transmitting means and radio receiving means;

the remote unit and the base station defining a two-way radio communication link, and also defining a separation distance between the remote unit and the base station;

measuring means for determining whether the separation distance exceeds a predetermined limit;

means responsive to the measuring means for causing the remote unit to transmit at the higher power level when the separation distance exceeds the limit; and

alarm means for indicating when the separation distance exceeds the limit, and for indicating when a personal hazard is detected.

18. A personal alarm system, comprising:

a remote unit including radio transmitting means and radio receiving means;

the remote unit transmitting means being able to transmit at more than one power level and defining a plurality of transmitting power levels;

a base station including radio transmitting means and radio receiving means;

the remote unit and the base station defining a two-way radio communication link, and the remote unit radio receiving means defining a received signal strength;

the remote unit including control means responsive to the received signal strength for causing the remote unit to transmit at a power level selected by a predetermined power-level function of the received signal strength;

the remote unit including at least one sensor means for detecting a personal hazard, and means for communicating the detected hazard to the base station; and

the remote unit including means for communicating an alarm function of the received signal strength, and the base station including means responsive to the communication for giving an alarm.

21. A personal alarm system, comprising:

a remote unit including a transmitter and a receiver,

the remote unit transmitter being capable of transmitting at more than one power level and defining a plurality of power levels,

a base station including a transmitter and a receiver, and defining a two-way communications link with the remote unit,

the base station receiver defining a received signal strength,

the base station transmitting a command responsive to the received signal strength,

the remote unit including a control circuit responsive to a received command for selecting the transmission power level,

the remote unit including a sensor for detecting a hazard, the sensor defining a sensor status, and the remote unit transmitter connected for communicating the status,

the base station including an alarm responsive to the communicated status for giving an alarm when a hazard is detected.

22. The personal alarm system as set forth in claim 21, wherein the received signal strength is further defined by a voltage level on a signal line and the control circuit includes an analog-to-digital converter connected to receive the signal line and to provide digital output signals connected to address input lines of a read-only memory, the memory containing information defining a power-level function, the memory having digital output lines defining the command for selecting the transmission power level.

24. The weather alarm system as set forth in claim 23, wherein the navigational receiver also provides a time-of-day, and the transmitter also communicates the time-of-day for display by the base station.

25. The weather alarm system as set forth in claim 23, wherein the transmitter also communicates weather parameters for display by the base station.

26. The weather alarm system as set forth in claim 23, wherein the base station means responsive to the communication includes a radio receiver.

27. The weather alarm system as set forth in claim 23, wherein the base station means responsive to the communication includes a modem.

28. The weather alarm system as set forth in claim 23, wherein the navigational receiver includes a low-power standby mode and a normal operating mode and is responsive to the determination for switching from the standby mode to the normal operating mode.

30. The personal alarm system remote unit as set forth in claim 29, wherein the radio transmitter and receiver comprise a wireless telephone for use with a wireless telephone network.

31. The personal alarm system remote unit as set forth in claim 30, further including means connected to the manually operated switch for initiating a wireless telephone call to the 911 dedicated public safety help telephone number.

32. The personal alarm system remote unit as set forth in claim 30, wherein the wireless telephone is a cellular telephone for operation with a cellular telephone network.

33. The personal alarm system remote unit as set forth in claim 30, wherein the wireless telephone is a personal communications services telephone for operation with a personal communications services telephone network.

34. The personal alarm system remote unit as set forth in claim 30, wherein the wireless telephone is a radio telephone for operation with a radio telephone network.

35. The personal alarm system remote unit as set forth in claim 30, further including a plurality of manually operated switches connected for selectively initiating telephone calls to any one of a plurality of predetermined telephone numbers.

36. The personal alarm system remote unit as set forth in claim 35, wherein one of the predetermined telephone numbers is the 911 dedicated public safety help telephone number.

37. The personal alarm system remote unit as set forth in claim 35, further including means for manually programming at least some of the predetermined telephone numbers.

39. The remote unit as set forth in claim 38, wherein the circuit for providing the first variable is a sensor having an output signal and the value of the first variable is an electrical parameter of the output signal and defines a sensor status, and the transmitted function of the first variable is the sensor status.

40. The remote unit as set forth in claim 39, wherein the circuit for providing the first variable includes a plurality of sensors, each having a sensor output signal having a value defined by an electrical parameter of the sensor output signal, and wherein the plurality of sensor output signals defines a sensor status vector, and the communications transmitter is connected for transmitting the sensor status vector, and wherein the circuit for determining whether a predetermined change has occurred determines whether a predetermined change has occurred within the defined status vector.

41. The remote unit as set forth in claim 38, wherein the circuit for providing the first variable is a pair of electrical contacts defining a manually operated switch, and wherein the value of the first variable is one of a closed circuit and an open circuit defining a switch status, and the transmitted function of the first variable is the switch status.

42. The remote unit as set forth in claim 41, wherein the manually operated switch defines a panic button.

43. The remote unit as set forth in claim 41, wherein the circuit for providing the first variable is a plurality of switches, and wherein the value of the first variable defines a vector of values, each value being one of a contact closure and an open circuit, defining a switch status vector, and the transmitted function of the first variable is the switch status vector.

44. The remote unit as set forth in claim 43, wherein the plurality of switches defines a manually operated numeric input device.

45. The remote unit as set forth in claim 43, wherein the plurality of switches defines a manually operated alphanumeric input device.

46. The remote unit as set forth in claim 38, wherein the circuit for providing the second variable is a means for storing a number, and the value of the second variable is the stored number.

47. The remote unit as set forth in claim 46, further including means for providing a patient identification code for storage as the value of the second variable, and wherein the circuit for providing the first variable includes at least one sensor for monitoring a physiological environmental parameter and defining a sensor status, the transmitted function of the first variable being the sensor status, and the remote unit defining a patient monitor.

48. The remote unit as set forth in claim 46, further including means for connecting an input device for providing the location of the remote unit for storage as the value of the second variable, and wherein the circuit for providing the first variable includes a sensor for monitoring an environmental parameter and defining a sensor status, the transmitted function of the first variable being the sensor status, and the remote unit defining an environmental monitor.

49. The environmental monitor as set forth in claim 48 in combination with a plurality of manually operated switches for providing the location of the remote unit.

50. The environmental monitor as set forth in claim 48 in combination with a dynamic location determining device for providing the location of the remote unit.

51. The environmental monitor as set forth in claim 50, wherein the dynamic location determining device is a navigational receiver.

52. The environmental monitor as set forth in claim 51, wherein the navigational receiver operates with a satellite navigational system.

53. A method for remotely monitoring an environmental parameter, comprising the steps of:

providing an environmental monitor as set forth in claim 48;

providing an input device for supplying a number representing a location;

connecting the input device to the environmental monitor via the connecting means;

determining the location of the environmental monitor;

using the input device to provide a number corresponding to the location of the environmental monitor;

storing the number in the number storing means;

disconnecting the input device from the connecting means;

monitoring an environmental parameter;

activating the communications transmitter when a predetermined change in the value of the monitored parameter occurs;

transmitting the sensor status and the stored location of the environmental monitor.

54. The method as set forth in claim 53, wherein the input device is a plurality of manually operated switches and wherein the location of the environmental monitor is determined using a GPS receiver, and the number representing the location for storage in the number storing means is entered using the manually operated switches.

55. The method as set forth in claim 53, wherein the input device is a GPS receiver having means for connecting to the environmental monitor, the receiver being operated to determine the environmental monitor location and to provide a number representing the location for storage in the number storing means.

56. The remote unit as set forth in claim 38, wherein the circuit for providing the second variable is a dynamic location determining means, and the value of the second variable is the location of the remote unit.

57. The remote unit as set forth in claim 56, wherein the dynamic location determining means is a navigational receiver.

58. The remote unit as set forth in claim 57, wherein the navigational receiver is a LORAN receiver.

59. The remote unit as set forth in claim 57, wherein the navigational receiver is a satellite navigational system receiver.

60. The remote unit as set forth in claim 59, wherein the satellite navigational receiver is a GPS receiver.

61. The remote unit as set forth in claim 57, wherein the circuit providing the first variable is a water immersion sensor and wherein immersion of the remote unit in water activates the communications transmitter for transmitting the remote unit location, the remote unit defining a man-over-board monitor.

62. The man-over-board monitor as defined in claim 61, further including a beacon activated when the monitor is immersed in water.

63. The man-over-board monitor as set forth in claim 62, wherein the beacon is a visual beacon.

64. The man-over-board monitor as set forth in claim 62, wherein the beacon is an audible beacon.

65. The man-over-board monitor as set forth in claim 61, adapted for operation from a battery and enclosed in a waterproof floatation device.

66. The man-over-board monitor as set forth in claim 65, wherein the waterproof floatation device is a life vest.

67. The remote unit as set forth in claim 57, wherein the circuit for providing the first variable includes:

a weather surveillance radar receiver providing weather parameters within a predetermined weather region, and identifying the weather region,

a first memory storing information defining a geographical zone relative to the remote unit location,

a circuit combining the remote unit location and the geographical zone to define a local weather zone,

a second memory storing information defining at least one weather parameter threshold,

means for determining that the local weather zone is within the identified weather region, and that a received weather parameter exceeds the at least one weather parameter threshold, and

the communications transmitter connected to communicate the result of the determination and defining a remote weather alarm

whereby a geographical zone is specified and weather parameters within the zone are monitored and compared with parameter thresholds and the result of the comparison is transmitted, permitting remote monitoring of weather conditions within a predefined region.

68. The remote weather alarm as defined in claim 67, further including the navigational receiver providing time-of-day and the communications transmitter connected to communicate the time-of-day.

69. The remote weather alarm as defined in claim 67, further including the communications transmitter connected for communicating received weather parameters.

70. The remote weather alarm as defined in claim 67, further including the first and second memories combined into a single memory.

71. The remote unit as set forth in claim 57, wherein the circuit for providing the first variable includes:

means for providing time-of-day,

a first memory for storing information defining a geographic region,

a second memory storing information defining a predetermined positional status and a predetermined time interval, and further defining a curfew, and

a circuit for comparing the remote unit location, the defined geographic zone, the predetermined positional status, the time-of-day and the curfew, and defining a positional and time status, the positional and time status defining the value of the first variable, the remote unit defining an invisible fence monitor, and

the communications transmitter connected for communicating the positional and time status.

72. The invisible fence monitor as defined in claim 71, wherein the positional and time status define a curfew violation and the monitor includes alarm and enforcement means responsive to the curfew violation.

73. The invisible fence monitor as defined in claim 71, wherein the first and second memories are combined to form a single memory, so that the information defining a geographic region and the information defining a curfew are stored in the single memory.

74. The invisible fence monitor as defined in claim 71, wherein the communications transmitter is connected to transmit the monitor location and the time-of-day.

75. The remote unit as set forth in claim 38, further including a microphone connected to the communications transmitter for providing a one-way voice channel.

76. The remote unit as set forth in claim 38, further including a communications receiver.

77. The remote unit as set forth in claim 76, wherein the communications transmitter and the communications receiver are adapted for operation with a radio relay system.

78. The remote unit as set forth in claim 76, wherein the communications transmitter and the communications receiver are adapted for operation with a radiotelephone system.

79. The remote unit as set forth in claim 76, wherein the communications transmitter and the communications receiver are adapted for operation with a cellular telephone system.

80. The remote unit as set forth in claim 76, wherein the communications transmitter and the communications receiver are adapted for operation with a personal communicator system.

81. The remote unit as set forth in claim 76, wherein the communications transmitter and the communications receiver are adapted for operation with a wireless communications system.

82. The remote unit as set forth in claim 76, further including a microphone connected to the communications transmitter and a speaker connected to the communications receiver for providing a two-way voice link.

23. A weather alarm system, comprising:

a remote unit including,

a navigational receiver providing a remote unit location,

a weather surveillance radar receiver providing weather parameters within a predetermined weather region, and identifying the weather region,

a first memory storing information defining a geographical zone relative to the remote unit location,

a circuit combining the remote unit location and the geographical zone to define a local weather zone,

a second memory storing information defining at least one weather parameter threshold,

means for determining that the local weather zone is within the identified weather region, and that a received weather parameter exceeds the at least one weather parameter threshold,

a transmitter connected to communicate the result of the determination; and

a base station including means responsive to the communication for giving an alarm and for displaying the result of the determination.

29. A personal alarm system remote unit, comprising:

a radio transmitter and radio receiver for providing a two-way radio communication link;

a navigational receiver for providing a location of the remote unit;

a manually operated switch defining a pair of electrical contacts for providing an output signal;

the radio transmitter connected for transmitting the remote unit location and the switch output signal; and

a microphone and speaker connected with the radio transmitter and receiver for providing a two-way voice channel via the two-way radio communication link.

38. A remote unit, comprising:

a communications transmitter;

a circuit for providing a first variable having a value;

a circuit for determining whether a predetermined change in the value of the first variable has occurred;

a circuit for providing a second variable having a value; and

the communications transmitter connected for transmitting the value of the second variable and the value of a function of the first variable when the predetermined change in the value of the first variable has occurred.

83. A remote unit, comprising:

a communications transmitter;

a circuit for providing a first variable having a value;

a circuit for determining whether a predetermined change in the value of the first variable has occurred;

the communications transmitter connected for transmitting the value of the first variable when the predetermined change in the value of the first variable has occurred; and

a communications receiver.

84. A remote monitoring system, comprising:

a remote unit including,

a communications transmitter,

a circuit for providing a first variable having a value,

a circuit for determining whether a predetermined change in the value of the first variable has occurred,

the communications transmitter connected for transmitting the value of the first variable when the predetermined change in the value of the first variable has occurred, and

a communications receiver; and

a base station including,

a communications transmitter,

a communications receiver defining a two-way communications link with the remote unit, and

the base station including alarm and display means responsive to a received value of the first variable.