U.S. patent application number 12/390166 was filed with the patent office on 2009-06-18 for method and apparatus for detecting moisture in building materials.
Invention is credited to Lawrence Kates.
Application Number | 20090153336 12/390166 |
Document ID | / |
Family ID | 37449934 |
Filed Date | 2009-06-18 |
United States Patent
Application |
20090153336 |
Kind Code |
A1 |
Kates; Lawrence |
June 18, 2009 |
METHOD AND APPARATUS FOR DETECTING MOISTURE IN BUILDING
MATERIALS
Abstract
A moisture sensor system is described. In one embodiment, the
provides an adjustable threshold level for the sensed moisture
level. The adjustable threshold allows the moisture sensor to
adjust to ambient conditions, aging of components, and other
operational variations while still providing a relatively sensitive
detection capability. In one embodiment, the adjustable threshold
moisture sensor is used in an intelligent sensor system that
includes one or more intelligent sensor units and a base unit that
can communicate with the moisture sensor units. When one or more of
the moisture sensor units detects a excess moisture the moisture
sensor unit communicates with the base unit and provides data
regarding the moisture condition. The base unit can contact a
supervisor or other responsible person by a plurality of
techniques, such as, telephone, pager, cellular telephone, Internet
(and/or local area network), etc. In one embodiment, one or more
wireless repeaters are used between the moisture sensor units and
the base unit to extend the range of the system and to allow the
base unit to communicate with a larger number of sensors.
Inventors: |
Kates; Lawrence; (Corona Del
Mar, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
37449934 |
Appl. No.: |
12/390166 |
Filed: |
February 20, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11562352 |
Nov 21, 2006 |
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12390166 |
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11233931 |
Sep 23, 2005 |
7142123 |
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11562352 |
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Current U.S.
Class: |
340/602 ;
340/870.01 |
Current CPC
Class: |
E04F 19/04 20130101;
G08B 25/009 20130101; G08B 21/20 20130101; E04F 2019/0422 20130101;
G08B 19/00 20130101; G01N 27/048 20130101 |
Class at
Publication: |
340/602 ;
340/870.01 |
International
Class: |
G08B 21/00 20060101
G08B021/00 |
Claims
1. A moisture sensor system, comprising: a sensor unit comprising a
moisture sensor provided to a moisture probe, said sensor unit
configured to receive instructions, said sensor unit configured to
report a severity of a moisture level when said sensor unit
determines that data measured by said moisture sensor fails a
threshold test, said sensor unit configured to adjust said
threshold according to sensor reading taken during a specified time
period, wherein said threshold is computed as an average of a
plurality of sensor data values.
2. A moisture sensor system, comprising: a sensor unit comprising a
moisture sensor provided to a moisture probe, said sensor unit
configured to receive instructions, said sensor unit configured to
report a severity of a moisture level when said sensor unit
determines that data measured by said moisture sensor fails a
threshold test, said sensor unit configured to adjust said
threshold according to sensor reading taken during a specified time
period, wherein said threshold is computed at least in part as a
weighted average of a plurality of sensor data values.
3. A moisture sensor system, comprising: a sensor unit comprising a
moisture sensor provided to a moisture probe, said sensor unit
configured to receive instructions, said sensor unit configured to
report a severity of a moisture level when said sensor unit
determines that data measured by said moisture sensor fails a
threshold test, said sensor unit configured to adjust said
threshold according to sensor reading taken during a specified time
period, wherein said severity is computed according to how far a
sensor reading has risen above said threshold.
4. A moisture sensor system, comprising: a sensor unit comprising a
moisture sensor provided to a moisture probe, said sensor unit
configured to receive instructions, said sensor unit configured to
report a severity of a moisture level when said sensor unit
determines that data measured by said moisture sensor fails a
threshold test, said sensor unit configured to adjust said
threshold according to sensor reading taken during a specified time
period, wherein said severity is computed at least in part as a
function of how far and how rapidly sensor readings have risen
above said threshold value.
5. A moisture sensor system, comprising: a sensor unit comprising a
moisture sensor provided to a moisture probe, said sensor unit
configured to receive instructions, said sensor unit configured to
report a severity of a moisture level when said sensor unit
determines that data measured by said moisture sensor fails a
threshold test, said sensor unit configured to adjust said
threshold according to sensor reading taken during a specified time
period, wherein said severity is computed at least in part as a
function of how many sensor readings have been measured above said
threshold value.
6. A moisture sensor system, comprising: a sensor unit comprising a
moisture sensor provided to a moisture probe, said sensor unit
configured to receive instructions, said sensor unit configured to
report a severity of a moisture level when said sensor unit
determines that data measured by said moisture sensor fails a
threshold test, said sensor unit configured to adjust said
threshold according to sensor reading taken during a specified time
period, wherein said severity is computed as a function of what
percentage of recent sensor readings have been measured above said
threshold value.
7. The system of claim 1, further comprising means for wirelessly
transmitting data from said moisture sensor to a monitoring
station.
8. The system of claim 1, further comprising means for wirelessly
transmitting resistance data to a monitoring station.
9. The system of claim 1, further comprising means for receiving
instructions to close a water shutoff valve.
10. The system of claim 1, wherein said sensor unit is configured
as a wireless sensor unit configured to report data measured by
said moisture sensor when said wireless sensor determines that said
moisture data fails a threshold test, said wireless sensor unit
configured to operating in a low-power mode when not transmitting
or receiving data.
11. The system of claim 1, further comprising a self-test
module.
12. The system of claim 1, wherein said self-test module provides a
resistor to said first and second conductors.
13. The system of claim 1, further comprising a monitoring computer
configured to attempt to contact a responsible party by
telephone.
14. The system of claim 1, further comprising a monitoring computer
configured to attempt to contact a responsible party by cellular
telephone.
15. The system of claim 1, further comprising a monitoring computer
configured to attempt to contact a responsible party by cellular
text messaging.
16. The system of claim 1, further comprising a monitoring computer
configured to attempt to contact a responsible party by pager.
17. The system of claim 1, further comprising a monitoring computer
configured to attempt to contact a responsible party by
Internet.
18. The system of claim 1, further comprising a monitoring computer
configured to attempt to contact a responsible party by email.
19. The system of claim 1, further comprising a monitoring computer
configured to attempt to contact a responsible party by Internet
instant messaging.
20. The system of claim 1, further comprising a monitoring computer
is configured to provide plots of moisture levels.
21. The system of claim 1, wherein said system is configured to
receive an instruction to change a status reporting interval.
22. The system of claim 1, wherein said system is configured to
receive an instruction to change a sensor data reporting
interval.
23. The system of claim 1, wherein a monitoring computer is
configured to monitor a status of said sensor unit.
24. The moisture sensor system of claim 1, wherein said severity of
a moisture level depends at least in part on a length of time said
moisture sensor has detected moisture above a threshold level.
25. The moisture sensor system of claim 1, wherein said severity of
a moisture level depends at least in part on a rate of raise in
said moisture level.
26. The sensor system of claim 1, said moisture probe comprising: a
first probe comprising a first conductor with a plurality of pins;
a second probe comprising a second conductor with a plurality of
pins; and a substrate provided to said first probe and said second
probe, said moisture sensor configured to measure an impedance
between said first probe and said second probe.
27. The system of claim 26, wherein said impedance comprises a
resistance.
28. The system of claim 26, wherein said impedance comprises a
reactance.
29. The system of claim 26, wherein said first and second
conductors are substantially linear.
30. The system of claim 26, wherein said first and second
conductors are substantially linear and attached to said substrate
in a substantially parallel alignment.
31. The system of claim 26, wherein a peel-and-stick adhesive is
provided to said substrate.
32. The system of claim 26, wherein an adhesive is provided to a
back side of said substrate.
33. The system of claim 26, wherein an adhesive is provided to a
front side of said substrate and wherein said first and second
conductors are provided to said front side of said substrate.
34. The system of claim 26, wherein said sensor unit configured as
a wireless sensor unit configured to report data measured by said
moisture sensor when said wireless sensor determines that said
moisture data fails a threshold test, said wireless sensor unit
configured to operating in a low-power mode when not transmitting
or receiving data.
35. The system of claim 26, wherein said substrate comprises a
baseboard molding.
36. The system of claim 26, wherein said substrate comprises a wall
molding.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of application
Ser. No. 11/562,352, filed Nov. 21, 2006, titled "METHOD AND
APPARATUS FOR DETECTING MOISTURE IN BUILDING MATERIALS," which is a
continuation of application Ser. No. 11/233,931, filed Sep. 23,
2005, titled "METHOD AND APPARATUS FOR DETECTING MOISTURE IN
BUILDING MATERIALS," now U.S. Pat. No. 7,142,123, the disclosure of
which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a sensor system for
detecting and determining the severity of moisture in building
materials, such as wood, drywall, plaster, etc.
[0004] 2. Description of the Related Art
[0005] Maintaining and protecting a building or complex is
difficult and costly. Some conditions, such as fires, gas leaks,
etc., are a danger to the occupants and the structure. Other
malfunctions, such as moisture in roofs, plumbing, walls, etc., are
not necessarily dangerous for the occupants, but can, nevertheless,
cause considerable damage. In many cases, an adverse ambient
condition such as water leakage, fire, etc., is not detected in the
early stages when the damage and/or danger is relatively small.
Sensors can be used to detect such adverse ambient conditions, but
sensors present their own set of problems. For example, adding
sensors, such as, for example, smoke detectors, water sensors, and
the like in an existing structure can be prohibitively expensive
due to the cost of installing wiring between the remote sensors and
a centralized monitoring device used to monitor the sensors. Adding
wiring to provide power to the sensors further increases the
cost.
SUMMARY
[0006] The present invention solves these and other problems by
providing a relatively low cost, robust, wireless sensor system
that provides an extended period of operability without
maintenance. The system includes one or more intelligent sensor
units and a base unit that can communicate with the sensor units.
When one or more of the sensor units detects an anomalous condition
(e.g., moisture, smoke, fire, water, etc.) the sensor unit
communicates with the base unit and provides data regarding the
anomalous condition. The base unit can contact a supervisor or
other responsible person by a plurality of techniques, such as,
telephone, pager, cellular telephone, Internet (and/or local area
network), etc. In one embodiment, one or more wireless repeaters
are used between the sensor units and the base unit to extend the
range of the system and to allow the base unit to communicate with
a larger number of sensors.
[0007] In one embodiment, the sensor system includes a number of
sensor units located throughout a building that sense conditions
and report anomalous results back to a central reporting station.
The sensor units measure conditions that might indicate a fire,
water leak, etc. The sensor units report the measured data to the
base unit whenever the sensor unit determines that the measured
data is sufficiently anomalous to be reported. The base unit can
notify a responsible person, such as, for example, a building
manager, building owner, private security service, etc. In one
embodiment, the sensor units do not send an alarm signal to the
central location. Rather, the sensors send quantitative measured
data (e.g., smoke density, temperature rate of rise, etc.) to the
central reporting station.
[0008] In one embodiment, the sensor unit is placed in a building,
apartment, office, residence, etc. In order to conserve battery
power, the sensor is normally placed in a low-power mode. In one
embodiment, while in low power mode, the sensor unit takes regular
sensor readings and evaluates the readings to determine if an
anomalous condition exists. If an anomalous condition is detected,
then the sensor unit "wakes up" and begins communicating with the
base unit or with a repeater. At programmed intervals, the sensor
also "wakes up" and sends status information to the base unit (or
repeater) and then listens for commands for a period of time.
[0009] In one embodiment, the sensor unit is bi-directional and
configured to receive instructions from the central reporting
station (or repeater). Thus, for example, the central reporting
station can instruct the sensor to: perform additional
measurements; go to a standby mode; wake up; report battery status;
change wake-up interval; run self-diagnostics and report results;
etc. In one embodiment, the sensor unit also includes a tamper
switch. When tampering with the sensor is detected, the sensor
reports such tampering to the base unit. In one embodiment, the
sensor reports its general health and status to the central
reporting station on a regular basis (e.g., results of
self-diagnostics, battery health, etc.).
[0010] In one embodiment, the sensor unit provides two wake-up
modes, a first wake-up mode for taking measurements (and reporting
such measurements if deemed necessary), and a second wake-up mode
for listening for commands from the central reporting station. The
two wake-up modes, or combinations thereof, can occur at different
intervals.
[0011] In one embodiment, the sensor units use spread-spectrum
techniques to communicate with the base unit and/or the repeater
units. In one embodiment, the sensor units use frequency-hopping
spread-spectrum. In one embodiment, each sensor unit has an
Identification code (ID) and the sensor units attaches its ID to
outgoing communication packets. In one embodiment, when receiving
wireless data, each sensor unit ignores data that is addressed to
other sensor units.
[0012] The repeater unit is configured to relay communications
traffic between a number of sensor units and the base unit. The
repeater units typically operate in an environment with several
other repeater units and thus, each repeater unit contains a
database (e.g., a lookup table) of sensor IDs. During normal
operation, the repeater only communicates with designated wireless
sensor units whose IDs appears in the repeater's database. In one
embodiment, the repeater is battery-operated and conserves power by
maintaining an internal schedule of when it's designated sensors
are expected to transmit and going to a low-power mode when none of
its designated sensor units is scheduled to transmit. In one
embodiment, the repeater uses spread-spectrum to communicate with
the base unit and the sensor units. In one embodiment, the repeater
uses frequency-hopping spread-spectrum to communicate with the base
unit and the sensor units. In one embodiment, each repeater unit
has an ID and the repeater unit attaches its ID to outgoing
communication packets that originate in the repeater unit. In one
embodiment, each repeater unit ignores data that is addressed to
other repeater units or to sensor units not serviced by the
repeater.
[0013] In one embodiment, the repeater is configured to provide
bi-directional communication between one or more sensors and a base
unit. In one embodiment, the repeater is configured to receive
instructions from the central reporting station (or repeater).
Thus, for example, the central reporting station can instruct the
repeater to: send commands to one or more sensors; go to standby
mode; "wake up"; report battery status; change wake-up interval;
run self-diagnostics and report results; etc.
[0014] The base unit is configured to receive measured sensor data
from a number of sensor units. In one embodiment, the sensor
information is relayed through the repeater units. The base unit
also sends commands to the repeater units and/or sensor units. In
one embodiment, the base unit includes a diskless PC that runs off
of a CD-ROM, flash memory, DVD, or other read-only device, etc.
When the base unit receives data from a wireless sensor indicating
that there may be an emergency condition (e.g., a fire or excess
smoke, temperature, water, flammable gas, etc.) the base unit will
attempt to notify a responsible party (e.g., a building manager) by
several communication channels (e.g., telephone, Internet, pager,
cell phone, etc.). In one embodiment, the base unit sends
instructions to place the wireless sensor in an alert mode
(inhibiting the wireless sensor's low-power mode). In one
embodiment, the base unit sends instructions to activate one or
more additional sensors near the first sensor.
[0015] In one embodiment, the base unit maintains a database of the
health, battery status, signal strength, and current operating
status of all of the sensor units and repeater units in the
wireless sensor system. In one embodiment, the base unit
automatically performs routine maintenance by sending commands to
each sensor to run a self-diagnostic and report the results. The
base unit collects such diagnostic results. In one embodiment, the
base unit sends instructions to each sensor telling the sensor how
long to wait between "wakeup" intervals. In one embodiment, the
base unit schedules different wakeup intervals to different sensors
based on the sensor's health, battery health, location, etc. In one
embodiment, the base unit sends instructions to repeaters to route
sensor information around a failed repeater.
[0016] In one embodiment, the sensor unit is configured to detect
moisture in building materials such as, for example, drywall, wood,
plaster, concrete, etc. In one embodiment, two or more conductors
are provided in proximity to the building material. The conductors
are provided to a sensor unit.
[0017] In one embodiment, a relatively low cost, robust, moisture
sensor system that provides an adjustable threshold level for the
sensed moisture level. The adjustable threshold allows the moisture
sensor to adjust to ambient conditions, aging of components, and
other operational variations while still providing a relatively
sensitive detection capability for hazardous conditions. The
adjustable threshold moisture sensor can operate for an extended
period of operability without maintenance or recalibration. In one
embodiment, the moisture sensor is self-calibrating and runs
through a calibration sequence at startup or at periodic intervals.
In one embodiment, the adjustable threshold moisture sensor is used
in an intelligent sensor system that includes one or more
intelligent sensor units and a base unit that can communicate with
the moisture sensor units. When one or more of the moisture sensor
units detects an anomalous condition (e.g., moisture, fire, water,
etc.) the moisture sensor unit communicates with the base unit and
provides data regarding the anomalous condition. The base unit can
contact a supervisor or other responsible person by a plurality of
techniques, such as, telephone, pager, cellular telephone, Internet
(and/or local area network), etc. In one embodiment, one or more
wireless repeaters are used between the moisture sensor units and
the base unit to extend the range of the system and to allow the
base unit to communicate with a larger number of sensors.
[0018] In one embodiment, the adjustable-threshold moisture sensor
sets a threshold level according to an average value of the
moisture sensor reading. In one embodiment, the average value is a
relatively long-term average. In one embodiment, the average is a
time-weighted average wherein recent sensor readings used in the
averaging process are weighted differently than less recent sensor
readings. The average is used to set the threshold level. When the
moisture sensor reading rises above the threshold level, the
moisture sensor indicates an alarm condition. In one embodiment,
the moisture sensor indicates an alarm condition when the moisture
sensor reading rises above the threshold value for a specified
period of time. In one embodiment, the moisture sensor indicates an
alarm condition when a statistical number of sensor readings (e.g.,
3 of 2, 5 of 3, 10 of 7, etc.) are above the threshold level. In
one embodiment, the moisture sensor indicates various levels of
alarm (e.g., notice, alert, alarm) based on how far above the
threshold the moisture sensor reading has risen and/or how rapidly
the moisture sensor reading has risen.
[0019] In one embodiment, the moisture sensor system includes a
number of sensor units located throughout a building that sense
conditions and report anomalous results back to a central reporting
station. The moisture sensor units measure conditions that might
indicate a fire, water leak, etc. The moisture sensor units report
the measured data to the base unit whenever the moisture sensor
unit determines that the measured data is sufficiently anomalous to
be reported. The base unit can notify a responsible person such as,
for example, a building manager, building owner, private security
service, etc. In one embodiment, the moisture sensor units do not
send an alarm signal to the central location. Rather, the moisture
sensors send quantitative measured data (e.g., moisture, rate of
rise, length of time, etc.) to the central reporting station.
[0020] In one embodiment, the moisture sensor system includes a
battery-operated sensor unit that detects moisture in building
materials. The moisture sensor unit is placed in a building,
apartment, office, residence, etc., and provided to a moisture
probe. In order to conserve battery power, the moisture sensor is
normally placed in a low-power mode. In one embodiment, while in
the low-power mode, the moisture sensor unit takes regular sensor
readings, adjusts the threshold level, and evaluates the readings
to determine if an anomalous condition exists. If an anomalous
condition is detected, then the moisture sensor unit "wakes up" and
begins communicating with the base unit or with a repeater. At
programmed intervals, the moisture sensor also "wakes up" and sends
status information to the base unit (or repeater) and then listens
for commands for a period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows a sensor system that includes a plurality of
sensor units that communicate with a base unit through a number of
repeater units.
[0022] FIG. 2 is a block diagram of a sensor unit.
[0023] FIG. 3 is a block diagram of a repeater unit.
[0024] FIG. 4 is a block diagram of the base unit.
[0025] FIG. 5 shows one embodiment of a network communication
packet used by the sensor units, repeater units, and the base
unit.
[0026] FIG. 6 is a flowchart showing operation of a sensor unit
that provides relatively continuous monitoring.
[0027] FIG. 7 is a flowchart showing operation of a sensor unit
that provides periodic monitoring.
[0028] FIG. 8 shows a sensor system wherein relatively low-cost
sensors provide sensor readings and/or status information to an
area monitor that communicates with a base unit.
[0029] FIG. 9 shows a moisture sensor that includes an impedance
sensor provided to one or more impedance probes.
[0030] FIG. 10 shows the impedance sensor from FIG. 9 provided to
an impedance probe configured as a pair of conductive strips.
[0031] FIG. 11 is a schematic of an impedance sensor configured to
measure impedance by using a voltage source and a current
sensor.
[0032] FIG. 12 is a schematic of an impedance sensor configured to
measure impedance by using a current source and a voltage
sensor.
[0033] FIG. 13 is a schematic of an impedance sensor configured to
measure impedance using a bridge.
[0034] FIG. 14 shows a moisture sensor that includes a
time/frequency domain impedance sensor provided to an impedance
probe.
[0035] FIG. 15 is a plot showing an example output of the
time-frequency domain impedance sensor when a relatively small damp
area is detected.
[0036] FIG. 16 is a plot showing an example output of the
time-frequency domain impedance sensor when a larger damp area is
detected.
[0037] FIG. 17 is a schematic of one embodiment of a time-domain
impedance sensor.
[0038] FIG. 18 is a rear view showing the impedance sensor provided
to a molding.
[0039] FIG. 19 is a front view of the molding from FIG. 9 showing
one method connecting the sensor unit 902 to the impedance
probe.
[0040] FIG. 20 shows an impedance probe configured for
peel-and-stick application to a molding.
[0041] FIG. 21 shows an impedance probe configured for
peel-and-stick application to a wall or other building
material.
[0042] FIG. 22 shows one installation of the moisture sensor unit
to an impedance probe provided between a wall or ceiling and a
molding, wherein the sensor unit is mounted to the wall (or
ceiling).
[0043] FIG. 23 shows one installation of the moisture sensor unit
to an impedance probe provided between a wall or ceiling and a
molding, wherein the sensor unit is mounted to the molding.
[0044] FIG. 24 shows the impedance probes from FIG. 20 or 21
wrapped around a corner.
[0045] FIG. 25 shows the impedance probes from FIG. 20 or 21
overlapped to cover a longer area.
[0046] FIG. 26 shows a moisture sensor and a self-test sensor
provided to a moisture probe.
DETAILED DESCRIPTION
[0047] FIG. 1 shows a sensor system 100 that includes a plurality
of sensor units 102-106 that communicate with a base unit 112
through a number of repeater units 110-111. The sensor units
102-106 are located throughout a building 101. Sensor units 102-104
communicate with the repeater 110. Sensor units 105-106 communicate
with the repeater 111. The repeaters 110-111 communicate with the
base unit 112. The base unit 112 communicates with a monitoring
computer system 113 through a computer network connection such as,
for example, Ethernet, wireless Ethernet, firewire port, Universal
Serial Bus (USB) port, bluetooth, etc. The computer system 113
contacts a building manager, maintenance service, alarm service, or
other responsible personnel 120 using one or more of several
communication systems such as, for example, telephone 121, pager
122, cellular telephone 123 (e.g., direct contact, voicemail, text,
etc.), and/or through the Internet and/or local area network 124
(e.g., through email, instant messaging, network communications,
etc.). In one embodiment, multiple base units 112 are provided to
the monitoring computer 113. In one embodiment, the monitoring
computer 113 is provided to more than one computer monitor, thus,
allowing more data to be displayed than can conveniently be
displayed on a single monitor. In one embodiment, the monitoring
computer 113 is provided to multiple monitors located in different
locations, thus, allowing the data from the monitoring computer 113
to be displayed in multiple locations.
[0048] The sensor units 102-106 include sensors to measure
conditions, such as, for example, smoke, temperature, moisture,
water, water temperature, humidity, carbon monoxide, natural gas,
propane gas, security alarms, intrusion alarms (e.g., open doors,
broken windows, open windows, and the like), other flammable gases,
radon, poison gases, etc. Different sensor units can be configured
with different sensors or with combinations of sensors. Thus, for
example, in one installation the sensor units 102 and 104 could be
configured with smoke and/or temperature sensors while the sensor
unit 103 could be configured with a humidity sensor.
[0049] The discussion that follows generally refers to the sensor
unit 102 as an example of a sensor unit, with the understanding
that the description of the sensor unit 102 can be applied to many
sensor units. Similarly, the discussion generally refers to the
repeater 110 by way of example, and not limitation. It will also be
understood by one of ordinary skill in the art that repeaters are
useful for extending the range of the sensor units 102-106 but are
not required in all embodiments. Thus, for example in one
embodiment, one or more of the sensor units 102-106 can communicate
directly with the base unit 112 without going through a repeater.
It will also be understood by one of ordinary skill in the art that
FIG. 1 shows only five sensor units (102-106) and two repeater
units (110-111) for purposes of illustration and not by way of
limitation. An installation in a large apartment building or
complex would typically involve many sensor units and repeater
units. Moreover, one of ordinary skill in the art will recognize
that one repeater unit can service relatively many sensor units. In
one embodiment, the sensor unit 102 can communicate directly with
the base unit 112 without going through a repeater 111.
[0050] When the sensor unit 102 detects an anomalous condition
(e.g., smoke, fire, water, etc.) the sensor unit communicates with
the appropriate repeater unit 110 and provides data regarding the
anomalous condition. The repeater unit 110 forwards the data to the
base unit 112, and the base unit 112 forwards the information to
the computer 113. The computer 113 evaluates the data and takes
appropriate action. If the computer 113 determines that the
condition is an emergency (e.g., fire, smoke, large quantities of
water), then the computer 113 contacts the appropriate personnel
120. If the computer 113 determines that the situation warrants
reporting, but is not an emergency, then the computer 113 logs the
data for later reporting. In this way, the sensor system 100 can
monitor the conditions in and around the building 101.
[0051] In one embodiment, the sensor unit 102 has an internal power
source (e.g., battery, solar cell, fuel cell, etc.). In order to
conserve power, the sensor unit 102 is normally placed in a
low-power mode. In one embodiment, using sensors that require
relatively little power, while in the low power mode the sensor
unit 102 takes regular sensor readings and evaluates the readings
to determine if an anomalous condition exists. In one embodiment,
using sensors that require relatively more power, while in the low
power mode the sensor unit 102 takes and evaluates sensor readings
at periodic intervals. If an anomalous condition is detected, then
the sensor unit 102 "wakes up" and begins communicating with the
base unit 112 through the repeater 110. At programmed intervals,
the sensor unit 102 also "wakes up" and sends status information
(e.g., power levels, self diagnostic information, etc.) to the base
unit (or repeater) and then listens for commands for a period of
time. In one embodiment, the sensor unit 102 also includes a tamper
detector. When tampering with the sensor unit 102 is detected, the
sensor unit 102 reports such tampering to the base unit 112.
[0052] In one embodiment, the sensor unit 102 provides
bi-directional communication and is configured to receive data
and/or instructions from the base unit 112. Thus, for example, the
base unit 112 can instruct the sensor unit 102 to perform
additional measurements, to go to a standby mode, to wake up, to
report battery status, to change wake-up interval, to run
self-diagnostics and report results, etc. In one embodiment, the
sensor unit 102 reports its general health and status on a regular
basis (e.g., results of self-diagnostics, battery health, etc.)
[0053] In one embodiment, the sensor unit 102 provides two wake-up
modes, a first wake-up mode for taking measurements (and reporting
such measurements if deemed necessary), and a second wake-up mode
for listening for commands from the central reporting station. The
two wake-up modes, or combinations thereof, can occur at different
intervals.
[0054] In one embodiment, the sensor unit 102 uses spread-spectrum
techniques to communicate with the repeater unit 110. In one
embodiment, the sensor unit 102 use frequency-hopping
spread-spectrum. In one embodiment, the sensor unit 102 has an
address or identification (ID) code that distinguishes the sensor
unit 102 from the other sensor units. The sensor unit 102 attaches
its ID to outgoing communication packets so that transmissions from
the sensor unit 102 can be identified by the repeater 110. The
repeater 110 attaches the ID of the sensor unit 102 to data and/or
instructions that are transmitted to the sensor unit 102. In one
embodiment, the sensor unit 102 ignores data and/or instructions
that are addressed to other sensor units.
[0055] In one embodiment, the sensor unit 102 includes a reset
function. In one embodiment, the reset function is activated by the
reset switch 208. In one embodiment, the reset function is active
for a prescribed interval of time. During the reset interval, the
transceiver 203 is in a receiving mode and can receive the
identification code from an external programmer. In one embodiment,
the external programmer wirelessly transmits a desired
identification code. In one embodiment, the identification code is
programmed by an external programmer that is connected to the
sensor unit 102 through an electrical connector. In one embodiment,
the electrical connection to the sensor unit 102 is provided by
sending modulated control signals (power line carrier signals)
through a connector used to connect the power source 206. In one
embodiment, the external programmer provides power and control
signals. In one embodiment, the external programmer also programs
the type of sensor(s) installed in the sensor unit. In one
embodiment, the identification code includes an area code (e.g.,
apartment number, zone number, floor number, etc.) and a unit
number (e.g., unit 1, 2, 3, etc.).
[0056] In one embodiment, the external programmer interfaces with
the controller 202 by using an optional programming interface 210.
In one embodiment, the programming interface 210 includes a
connector. In one embodiment, the programming interface 210
includes an infrared interface. In one embodiment, the programming
interface 210 includes an inductive coupling coil. In one
embodiment, the programming interface 210 includes one or more
capacitive coupling plates.
[0057] In one embodiment, the sensor communicates with the repeater
on the 900 MHz band. This band provides good transmission through
walls and other obstacles normally found in and around a building
structure. In one embodiment, the sensor communicates with the
repeater on bands above and/or below the 900 MHz band. In one
embodiment, the sensor, repeater, and/or base unit listen to a
radio frequency channel before transmitting on that channel or
before beginning transmission. If the channel is in use, (e.g., by
another device such as another repeater, a cordless telephone,
etc.) then the sensor, repeater and/or base unit changes to a
different channel. In one embodiment, the sensor, repeater and/or
base unit coordinate frequency hopping by listening to radio
frequency channels for interference and using an algorithm to
select a next channel for transmission that avoids the
interference. Thus, for example, in one embodiment, if a sensor
senses a dangerous condition and goes into a continuous
transmission mode, the sensor will test (e.g., listen to) the
channel before transmission to avoid channels that are blocked, in
use, or jammed. In one embodiment, the sensor continues to transmit
data until it receives an acknowledgement from the base unit that
the message has been received. In one embodiment, the sensor
transmits data having a normal priority (e.g., status information)
and does not look for an acknowledgement, and the sensor transmits
data having elevated priority (e.g., excess smoke, temperature,
etc.) until an acknowledgement is received.
[0058] The repeater unit 110 is configured to relay communications
traffic between the sensor 102 (and, similarly, the sensor units
103-104) and the base unit 112. The repeater unit 110 typically
operates in an environment with several other repeater units (such
as the repeater unit 111 in FIG. 1) and thus, the repeater unit 110
contains a database (e.g., a lookup table) of sensor unit IDs. In
FIG. 1, the repeater 110 has database entries for the Ids of the
sensors 102-104, and thus, the sensor 110 will only communicate
with sensor units 102-104. In one embodiment, the repeater 110 has
an internal power source (e.g., battery, solar cell, fuel cell,
etc.) and conserves power by maintaining an internal schedule of
when the sensor units 102-104 are expected to transmit. In one
embodiment, the repeater unit 110 goes to a low-power mode when
none of its designated sensor units is scheduled to transmit. In
one embodiment, the repeater 110 uses spread-spectrum techniques to
communicate with the base unit 112 and with the sensor units
102-104. In one embodiment, the repeater 110 uses frequency-hopping
spread-spectrum to communicate with the base unit 112 and the
sensor units 102-104. In one embodiment, the repeater unit 110 has
an address or identification (ID) code and the repeater unit 110
attaches its address to outgoing communication packets that
originate in the repeater (that is, packets that are not being
forwarded). In one embodiment, the repeater unit 110 ignores data
and/or instructions that are addressed to other repeater units or
to sensor units not serviced by the repeater 110.
[0059] In one embodiment, the base unit 112 communicates with the
sensor unit 102 by transmitting a communication packet addressed to
the sensor unit 102. The repeaters 110 and 111 both receive the
communication packet addressed to the sensor unit 102. The repeater
unit 111 ignores the communication packet addressed to the sensor
unit 102. The repeater unit 110 transmits the communication packet
addressed to the sensor unit 102 to the sensor unit 102. In one
embodiment, the sensor unit 102, the repeater unit 110, and the
base unit 112 communicate using Frequency-Hopping Spread Spectrum
(FHSS), also known as channel-hopping.
[0060] Frequency-hopping wireless systems offer the advantage of
avoiding other interfering signals and avoiding collisions.
Moreover, there are regulatory advantages given to systems that do
not transmit continuously at one frequency. Channel-hopping
transmitters change frequencies after a period of continuous
transmission, or when interference is encountered. These systems
may have higher transmit power and relaxed limitations on in-band
spurs. FCC regulations limit transmission time on one channel to
400 milliseconds (averaged over 10-20 seconds depending on channel
bandwidth) before the transmitter must change frequency. There is a
minimum frequency step when changing channels to resume
transmission. If there are 25 to 49 frequency channels, regulations
allow effective radiated power of 24 dBm, spurs must be -20 dBc,
and harmonics must be -41.2 dBc. With 50 or more channels,
regulations allow effective radiated power to be up to 30 dBm.
[0061] In one embodiment, the sensor unit 102, the repeater unit
110, and the base unit 112 communicate using FHSS wherein the
frequency hopping of the sensor unit 102, the repeater unit 110,
and the base unit 112 are not synchronized such that at any given
moment, the sensor unit 102 and the repeater unit 110 are on
different channels. In such a system, the base unit 112
communicates with the sensor unit 102 using the hop frequencies
synchronized to the repeater unit 110 rather than the sensor unit
102. The repeater unit 110 then forwards the data to the sensor
unit using hop frequencies synchronized to the sensor unit 102.
Such a system largely avoids collisions between the transmissions
by the base unit 112 and the repeater unit 110.
[0062] In one embodiment, the sensor units 102-106 all use FHSS and
the sensor units 102-106 are not synchronized. Thus, at any given
moment, it is unlikely that any two or more of the sensor units
102-106 will transmit on the same frequency. In this manner,
collisions are largely avoided. In one embodiment, collisions are
not detected but are tolerated by the system 100. If a collision
does occur, data lost due to the collision is effectively
re-transmitted the next time the sensor units transmit sensor data.
When the sensor units 102-106 and repeater units 110-111 operate in
asynchronous mode, then a second collision is highly unlikely
because the units causing the collisions have hopped to different
channels. In one embodiment, the sensor units 102-106, repeater
units 110-111, and the base unit 112 use the same hop rate. In one
embodiment, the sensor units 102-106, repeater units 110-111, and
the base unit 112 use the same pseudo-random algorithm to control
channel hopping, but with different starting seeds. In one
embodiment, the starting seed for the hop algorithm is calculated
from the ID of the sensor units 102-106, repeater units 110-111, or
the base unit 112.
[0063] In an alternative embodiment, the base unit communicates
with the sensor unit 102 by sending a communication packet
addressed to the repeater unit 110, where the packet sent to the
repeater unit 110 includes the address of the sensor unit 102. The
repeater unit 102 extracts the address of the sensor unit 102 from
the packet and creates and transmits a packet addressed to the
sensor unit 102.
[0064] In one embodiment, the repeater unit 110 is configured to
provide bi-directional communication between its sensors and the
base unit 112. In one embodiment, the repeater 110 is configured to
receive instructions from the base unit 110. Thus, for example, the
base unit 112 can instruct the repeater to: send commands to one or
more sensors; go to standby mode; "wake up"; report battery status;
change wake-up interval; run self-diagnostics and report results;
etc.
[0065] The base unit 112 is configured to receive measured sensor
data from a number of sensor units either directly, or through the
repeaters 110-111. The base unit 112 also sends commands to the
repeater units 110-111 and/or to the sensor units 102-106. In one
embodiment, the base unit 112 communicates with a diskless computer
113 that runs off of a CD-ROM. When the base unit 112 receives data
from sensor units 102-106 indicating that there may be an emergency
condition (e.g., a fire or excess smoke, temperature, water, etc.)
the computer 113 will attempt to notify the responsible party
120.
[0066] In one embodiment, the computer 113 maintains a database of
the health, power status (e.g., battery charge), and current
operating status of all of the sensor units 102-106 and the
repeater units 110-111. In one embodiment, the computer 113
automatically performs routine maintenance by sending commands to
each sensor unit 102-106 to run a self-diagnostic and report the
results. The computer 113 collects and logs such diagnostic
results. In one embodiment, the computer 113 sends instructions to
each sensor units 102-106 telling the sensor how long to wait
between "wakeup" intervals. In one embodiment, the computer 113
schedules different wakeup intervals to different sensor units
102-106 based on the sensor unit's health, power status, location,
etc. In one embodiment, the computer 113 schedules different wakeup
intervals to different sensor unit 102-106 based on the type of
data and urgency of the data collected by the sensor unit (e.g.,
sensor units that have smoke and/or temperature sensors produce
data that should be checked relatively more often than sensor units
that have humidity or moisture sensors). In one embodiment, the
base unit sends instructions to repeaters to route sensor
information around a failed repeater.
[0067] In one embodiment, the computer 113 produces a display that
tells maintenance personnel which sensor units 102-106 need repair
or maintenance. In one embodiment, the computer 113 maintains a
list showing the status and/or location of each sensor according to
the ID of each sensor.
[0068] In one embodiment, the sensor units 102-106 and/or the
repeater units 110-111 measure the signal strength of the wireless
signals received (e.g., the sensor unit 102 measures the signal
strength of the signals received from the repeater unit 110, the
repeater unit 110 measures the signal strength received from the
sensor unit 102 and/or the base unit 112). The sensor units 102-106
and/or the repeater units 110-111 report such signal strength
measurement back to the computer 113. The computer 113 evaluates
the signal strength measurements to ascertain the health and
robustness of the sensor system 100. In one embodiment, the
computer 113 uses the signal strength information to re-route
wireless communications traffic in the sensor system 100. Thus, for
example, if the repeater unit 110 goes offline or is having
difficulty communicating with the sensor unit 102, the computer 113
can send instructions to the repeater unit 111 to add the ID of the
sensor unit 102 to the database of the repeater unit 111 (and
similarly, send instructions to the repeater unit 110 to remove the
ID of the sensor unit 102), thereby routing the traffic for the
sensor unit 102 through the router unit 111 instead of the router
unit 110.
[0069] FIG. 2 is a block diagram of the sensor unit 102. In the
sensor unit 102, one or more sensors 201 and a transceiver 203 are
provided to a controller 202. The controller 202 typically provides
power, data, and control information to the sensor(s) 201 and the
transceiver 203. A power source 206 is provided to the controller
202. An optional tamper sensor 205 is also provided to the
controller 202. A reset device (e.g., a switch) 208 is proved to
the controller 202. In one embodiment, an optional audio output
device 209 is provided. In one embodiment, the sensor 201 is
configured as a plug-in module that can be replaced relatively
easily.
[0070] In one embodiment, the transceiver 203 is based on a TRF
6901 transceiver chip from Texas Instruments. Inc. In one
embodiment, the controller 202 is a conventional programmable
microcontroller. In one embodiment, the controller 202 is based on
a Field Programmable Gate Array (FPGA), such as, for example,
provided by Xilinx Corp. In one embodiment, the sensor 201 includes
an optoelectric smoke sensor with a smoke chamber. In one
embodiment, the sensor 201 includes a thermistor. In one
embodiment, the sensor 201 includes a humidity sensor. In one
embodiment, the sensor 201 includes a sensor, such as, for example,
a water level sensor, a water temperature sensor, a carbon monoxide
sensor, a moisture sensor, a water flow sensor, natural gas sensor,
propane sensor, etc.
[0071] The controller 202 receives sensor data from the sensor(s)
201. Some sensors 201 produce digital data. However, for many types
of sensors 201, the sensor data is analog data. Analog sensor data
is converted to digital format by the controller 202. In one
embodiment, the controller evaluates the data received from the
sensor(s) 201 and determines whether the data is to be transmitted
to the base unit 112. The sensor unit 102 generally conserves power
by not transmitting data that falls within a normal range. In one
embodiment, the controller 202 evaluates the sensor data by
comparing the data value to a threshold value (e.g., a high
threshold, a low threshold, or a high-low threshold). If the data
is outside the threshold (e.g., above a high threshold, below a low
threshold, outside an inner range threshold, or inside an outer
range threshold), then the data is deemed to be anomalous and is
transmitted to the base unit 112. In one embodiment, the data
threshold is programmed into the controller 202. In one embodiment,
the data threshold is programmed by the base unit 112 by sending
instructions to the controller 202. In one embodiment, the
controller 202 obtains sensor data and transmits the data when
commanded by the computer 113.
[0072] In one embodiment, the tamper sensor 205 is configured as a
switch that detects removal of or tampering with the sensor unit
102.
[0073] FIG. 3 is a block diagram of the repeater unit 110. In the
repeater unit 110, a first transceiver 302 and a second transceiver
304 are provided to a controller 303. The controller 303 typically
provides power, data, and control information to the transceivers
302, 304. A power source 306 is provided to the controller 303. An
optional tamper sensor (not shown) is also provided to the
controller 303.
[0074] When relaying sensor data to the base unit 112, the
controller 303 receives data from the first transceiver 302 and
provides the data to the second transceiver 304. When relaying
instructions from the base unit 112 to a sensor unit, the
controller 303 receives data from the second transceiver 304 and
provides the data to the first transceiver 302. In one embodiment,
the controller 303 conserves power by powering-down the
transceivers 302, 304 during periods when the controller 303 is not
expecting data. The controller 303 also monitors the power source
306 and provides status information, such as, for example,
self-diagnostic information and/or information about the health of
the power source 306, to the base unit 112. In one embodiment, the
controller 303 sends status information to the base unit 112 at
regular intervals. In one embodiment, the controller 303 sends
status information to the base unit 112 when requested by the base
unit 112. In one embodiment, the controller 303 sends status
information to the base unit 112 when a fault condition (e.g.,
battery low) is detected.
[0075] In one embodiment, the controller 303 includes a table or
list of identification codes for wireless sensor units 102. The
repeater 110 forwards packets received from, or sent to, sensor
units 102 in the list. In one embodiment, the repeater 110 receives
entries for the list of sensor units from the computer 113. In one
embodiment, the controller 303 determines when a transmission is
expected from the sensor units 102 in the table of sensor units and
places the repeater 110 (e.g., the transceivers 302, 304) in a
low-power mode when no transmissions are expected from the
transceivers on the list. In one embodiment, the controller 303
recalculates the times for low-power operation when a command to
change reporting interval is forwarded to one of the sensor units
102 in the list (table) of sensor units or when a new sensor unit
is added to the list (table) of sensor units.
[0076] FIG. 4 is a block diagram of the base unit 112. In the base
unit 112, a transceiver 402 and a computer interface 404 are
provided to a controller 403. The controller 403 typically provides
data and control information to the transceivers 402 and to the
interface. The interface 404 is provided to a port on the
monitoring computer 113. The interface 404 can be a standard
computer data interface, such as, for example, Ethernet, wireless
Ethernet, firewire port, Universal Serial Bus (USB) port,
bluetooth, etc.
[0077] FIG. 5 shows one embodiment of a communication packet 500
used by the sensor units, repeater units, and the base unit. The
packet 500 includes a preamble portion 501, an address (or ID)
portion 502, a data payload portion 503, and an integrity portion
504. In one embodiment, the integrity portion 504 includes a
checksum. In one embodiment, the sensor units 102-106, the repeater
units 110-111, and the base unit 112 communicate using packets such
as the packet 500. In one embodiment, the packets 500 are
transmitted using FHSS.
[0078] In one embodiment, the data packets that travel between the
sensor unit 102, the repeater unit 111, and the base unit 112 are
encrypted. In one embodiment, the data packets that travel between
the sensor unit 102, the repeater unit 111, and the base unit 112
are encrypted and an authentication code is provided in the data
packet so that the sensor unit 102, the repeater unit, and/or the
base unit 112 can verify the authenticity of the packet.
[0079] In one embodiment the address portion 502 includes a first
code and a second code. In one embodiment, the repeater 111 only
examines the first code to determine if the packet should be
forwarded. Thus, for example, the first code can be interpreted as
a building (or building complex) code and the second code
interpreted as a subcode (e.g., an apartment code, area code,
etc.). A repeater that uses the first code for forwarding, thus,
forwards packets having a specified first code (e.g., corresponding
to the repeater's building or building complex). Thus, alleviates
the need to program a list of sensor units 102 into a repeater,
since a group of sensors in a building will typically all have the
same first code but different second codes. A repeater so
configured, only needs to know the first code to forward packets
for any repeater in the building or building complex. This does,
however, raise the possibility that two repeaters in the same
building could try to forward packets for the same sensor unit 102.
In one embodiment, each repeater waits for a programmed delay
period before forwarding a packet. Thus reducing the chance of
packet collisions at the base unit (in the case of sensor unit to
base unit packets) and reducing the chance of packet collisions at
the sensor unit (in the case of base unit to sensor unit packets).
In one embodiment, a delay period is programmed into each repeater.
In one embodiment, delay periods are pre-programmed onto the
repeater units at the factory or during installation. In one
embodiment, a delay period is programmed into each repeater by the
base unit 112. In one embodiment, a repeater randomly chooses a
delay period. In one embodiment, a repeater randomly chooses a
delay period for each forwarded packet. In one embodiment, the
first code is at least 6 digits. In one embodiment, the second code
is at least 5 digits.
[0080] In one embodiment, the first code and the second code are
programmed into each sensor unit at the factory. In one embodiment,
the first code and the second code are programmed when the sensor
unit is installed. In one embodiment, the base unit 112 can
re-program the first code and/or the second code in a sensor
unit.
[0081] In one embodiment, collisions are further avoided by
configuring each repeater unit 111 to begin transmission on a
different frequency channel. Thus, if two repeaters attempt to
begin transmission at the same time, the repeaters will not
interfere with each other because the transmissions will begin on
different channels (frequencies).
[0082] FIG. 6 is a flowchart showing one embodiment of the
operation of the sensor unit 102 wherein relatively continuous
monitoring is provided. In FIG. 6, a power up block 601 is followed
by an initialization block 602. After initialization, the sensor
unit 102 checks for a fault condition (e.g., activation of the
tamper sensor, low battery, internal fault, etc.) in a block 603. A
decision block 604 checks the fault status. If a fault has
occurred, then the process advances to a block 605 were the fault
information is transmitted to the repeater 110 (after which, the
process advances to a block 612); otherwise, the process advances
to a block 606. In the block 606, the sensor unit 102 takes a
sensor reading from the sensor(s) 201. The sensor data is
subsequently evaluated in a block 607. If the sensor data is
abnormal, then the process advances to a transmit block 609 where
the sensor data is transmitted to the repeater 110 (after which,
the process advances to a block 612); otherwise, the process
advances to a timeout decision block 610. If the timeout period has
not elapsed, then the process returns to the fault-check block 603;
otherwise, the process advances to a transmit status block 611
where normal status information is transmitted to the repeater 110.
In one embodiment, the normal status information transmitted is
analogous to a simple "ping" which indicates that the sensor unit
102 is functioning normally. After the block 611, the process
proceeds to a block 612 where the sensor unit 102 momentarily
listens for instructions from the monitor computer 113. If an
instruction is received, then the sensor unit 102 performs the
instructions, otherwise, the process returns to the status check
block 603. In one embodiment, transceiver 203 is normally powered
down. The controller 202 powers up the transceiver 203 during
execution of the blocks 605, 609, 611, and 612. The monitoring
computer 113 can send instructions to the sensor unit 102 to change
the parameters used to evaluate data used in block 607, the listen
period used in block 612, etc.
[0083] Relatively continuous monitoring, such as shown in FIG. 6,
is appropriate for sensor units that sense relatively high-priority
data (e.g., smoke, fire, carbon monoxide, flammable gas, etc.). By
contrast, periodic monitoring can be used for sensors that sense
relatively lower priority data (e.g., humidity, moisture, water
usage, etc.). FIG. 7 is a flowchart showing one embodiment of
operation of the sensor unit 102 wherein periodic monitoring is
provided. In FIG. 7, a power up block 701 is followed by an
initialization block 702. After initialization, the sensor unit 102
enters a low-power sleep mode. If a fault occurs during the sleep
mode (e.g., the tamper sensor is activated), then the process
enters a wake-up block 704 followed by a transmit fault block 705.
If no fault occurs during the sleep period, then when the specified
sleep period has expired, the process enters a block 706 where the
sensor unit 102 takes a sensor reading from the sensor(s) 201. The
sensor data is subsequently sent to the monitoring computer 113 in
a report block 707. After reporting, the sensor unit 102 enters a
listen block 708 where the sensor unit 102 listens for a relatively
short period of time for instructions from monitoring computer 708.
If an instruction is received, then the sensor unit 102 performs
the instructions, otherwise, the process returns to the sleep block
703. In one embodiment, the sensor 201 and transceiver 203 are
normally powered down. The controller 202 powers up the sensor 201
during execution of the block 706. The controller 202 powers up the
transceiver during execution of the blocks 705, 707, and 708. The
monitoring computer 113 can send instructions to the sensor unit
102 to change the sleep period used in block 703, the listen period
used in block 708, etc.
[0084] In one embodiment, the sensor unit transmits sensor data
until a handshaking-type acknowledgement is received. Thus, rather
than sleep of no instructions or acknowledgements are received
after transmission (e.g., after the decision block 613 or 709) the
sensor unit 102 retransmits its data and waits for an
acknowledgement. The sensor unit 102 continues to transmit data and
wait for an acknowledgement until an acknowledgement is received.
In one embodiment, the sensor unit accepts an acknowledgement from
a repeater unit 111 and it then becomes the responsibility of the
repeater unit 111 to make sure that the data is forwarded to the
base unit 112. In one embodiment, the repeater unit 111 does not
generate the acknowledgement, but rather forwards an
acknowledgement from the base unit 112 to the sensor unit 102. The
two-way communication ability of the sensor unit 102 provides the
capability for the base unit 112 to control the operation of the
sensor unit 102 and also provides the capability for robust
handshaking-type communication between the sensor unit 102 and the
base unit 112.
[0085] Regardless of the normal operating mode of the sensor unit
102 (e.g., using the Flowcharts of FIGS. 6, 7, or other modes) in
one embodiment, the monitoring computer 113 can instruct the sensor
unit 102 to operate in a relatively continuous mode where the
sensor repeatedly takes sensor readings and transmits the readings
to the monitoring computer 113. Such a mode would can be used, for
example, when the sensor unit 102 (or a nearby sensor unit) has
detected a potentially dangerous condition (e.g., smoke, rapid
temperature rise, etc.)
[0086] FIG. 8 shows a sensor system 800 wherein one or more
relatively low-cost sensor units 802-804 provides sensor readings
and/or status information to an area monitor unit 810 that
communicates with the base unit 112 or with a repeater unit 110.
The sensor units 802-804 can be configured as embodiments of the
sensor unit 102 and/or as embodiments of the moisture sensor unit
1010. In one embodiment, the sensor units 802 and 804 are
configured for one-way communication to transmit information to the
area monitor 810. The moisture sensor unit 1010 can be configured
as one embodiment of the sensor unit 102. The moisture sensor unit
1010 can be configured as shown in FIG. 2 with a transceiver 203
that can both transmit and receive, or the transceiver 203 can be
configured for transmit-only operation. In one embodiment, the area
monitor 810 is configured in a manner similar to the repeater unit
110.
[0087] In one embodiment, the area monitor 810 is configured to
provide bi-directional communication with one or more sensor units
102. In one embodiment, the area monitor 810 is configured to
receive one-way communication from one or more sensor units
802-804.
[0088] In one embodiment, the sensor unit 802 sends a message to
the area monitor 810 whenever an anomalous sensor reading is
detected (e.g., water is detected, smoke is detected, etc.). In one
embodiment, the sensor unit 802 sends a stream of messages spaced
at desired intervals (e.g., every few seconds) to the area monitor
810 whenever an anomalous sensor reading is detected. In one
embodiment, the sensor unit 802 sends a status report (e.g., system
health, battery power status, etc.) to the area monitor 810 at a
desired regular interval (e.g., every hour, every day, every few
hours, etc.). The area monitor forwards messages from the sensor
system 800 to the monitoring system 113. In one embodiment, the
monitoring system 113 and/or area monitor 810 can determine that
the sensor unit 802 has failed based on status information received
from the sensor unit 802 and/or based on a lack of status
information from the sensor unit 802. The area monitor 810 expects
to receive periodic status updates from the sensor 802, thus, the
area monitor (and the central monitor 113) can assume that the
sensor unit 802 has failed or been removed if such regular status
updates are not received.
[0089] In one embodiment, the sensor unit 802 send actual sensor
data to the area monitor 810 and the area monitor forwards such
data to the central monitoring system 113 for analysis. Thus,
unlike simple alarm systems that simply provide on/off-type
sensors, the sensor units 802-804 and 102-106 provide actual sensor
readings that can be analyzed by the monitoring system to determine
or estimate the severity of a problem (e.g., the amount of smoke,
the amount of water, the rate of increase in smoke, water,
temperature, etc.).
[0090] In one embodiment, the monitoring system 113 maintains data
received from the sensor units 802-804 and 102-106 to help in
maintenance of the sensor system. In one embodiment, maintenance
personnel are expected to test each sensor unit on a regular basis
(e.g., semi-annually, annually, bi-annually, monthly, etc.) to make
sure the sensor is working. Thus, for example, in one embodiment,
the maintenance personnel are expected to expose each moisture
sensor 1010 to water to test the operation of the sensor and to
make sure that a "water-sensed" message is transmitted to the
monitoring system 113. Similarly, the maintenance personnel can be
tasked with exposing each smoke sensor to smoke. Thus, if the
monitoring system database shows that a particular sensor unit has
not reported a sensor event (e.g., water detected, smoke detected,
etc.) in a period corresponding to the maintenance interval, the
monitoring system 113 can report that the sensor unit has failed or
that the sensor unit has not been tested according to the testing
schedule. In this manner, supervisory personnel can monitor the
actions of maintenance personnel by examining the database
maintained by the system 113 to make sure that each sensor has been
activated and tested according the desired maintenance
schedule.
[0091] The database maintained by the monitoring system 113 can
also be used to provide plots of sensor activations and to indicate
possible trouble areas in a building or structure. Thus, for
example, if a particular water sensor has been activated on a
regular basis, the monitoring system 113 can indicate that a
potential problem exists in the area monitored by that sensor and
thus, alert the maintenance or supervisory personnel.
[0092] Excess moisture in a structure can cause severe problems
such as rotting, growth of molds, mildew, and fungus, etc.
(hereinafter referred to generically as fungus). In one embodiment,
the sensor 201 includes a moisture sensor. In one embodiment, the
monitoring system 100 detects conditions favorable for fungus
(e.g., mold, mildew, fungus, etc.) growth by measuring moisture
content of the building material at one or more locations of a
building. In one embodiment, sensor system is used to detect
moisture in building materials, such as, for example, drywall,
wood, concrete, plaster, stucco, etc. In one embodiment, the sensor
unit 102 includes a moisture sensor and one or more moisture probes
coupled to the building material. The moisture probes are provided
to the building material to allow the sensor unit 102 to detect
and/or measure the presence of moisture in the material. Moisture
in the building material is generally the result of a leak (e.g.,
plumbing leak, roof leak, stucco leak, etc.), invasion of ground
water, trapped humidity, or condensation. In one embodiment, the
severity of a moisture problem is ascertained by the sensor unit
102 (or the monitoring computer 113) by measuring (or estimating)
the rate of rise in the moisture level and/or by measuring (or
estimating) the size of a moist area, and/or by measuring (or
estimating) the amount of moisture in the building material.
[0093] In one embodiment, the monitoring computer 113 compares
moisture measurements taken from different sensor units in order to
detect areas that have excess moisture. Thus, for example, the
monitoring computer 113 can compare the moisture readings from a
first sensor unit 102 in a first attic area, to a moisture reading
from a second sensor unit 102 in a second area. For example, the
monitoring computer can take moisture readings from a number of
attic areas to establish a baseline moisture reading and then
compare the specific moisture readings from various sensor units to
determine if one or more of the units are measuring excess
moisture. The monitoring computer 113 would flag areas of excess
moisture for further investigation by maintenance personnel. In one
embodiment, the monitoring computer 113 maintains a history of
moisture readings for various sensor units and flags areas that
show an unexpected increase in moisture for investigation by
maintenance personnel.
[0094] The monitoring station 113 collects moisture readings from
the first moisture sensor and the second moisture sensor and
indicates conditions favorable for fungus growth by comparing the
first moisture data and the second moisture data. In one
embodiment, the monitoring station 113 establishes a baseline
moisture by comparing moisture readings from a plurality of
moisture sensors and indicates possible fungus growth conditions in
the first building area when at least a portion of the first
moisture data exceeds the baseline moisture by a specified amount.
In one embodiment, the monitoring station 113 establishes a
baseline moisture by comparing moisture readings from a plurality
of moisture sensors and indicates possible fungus growth conditions
in the first building area when at least a portion of the first
moisture data exceeds the baseline moisture by a specified
percentage.
[0095] In one embodiment, the monitoring station 113 establishes a
baseline moisture history by comparing moisture readings from a
plurality of moisture sensors and indicates possible fungus growth
conditions in the first building area when at least a portion of
the first moisture data exceeds the baseline moisture history by a
specified amount over a specified period of time. In one
embodiment, the monitoring station 113 establishes a baseline
moisture history by comparing moisture readings from a plurality of
moisture sensors over a period of time and indicates possible
fungus growth conditions in the first building area when at least a
portion of the first moisture data exceeds the baseline moisture by
a specified percentage of a specified period of time.
[0096] In one embodiment, the sensor unit 102 transmits moisture
data when it determines that the moisture data fails a threshold
test. In one embodiment, the moisture threshold for the threshold
test is provided to the sensor unit 102 by the monitoring station
113. In one embodiment, the moisture threshold for the threshold
test is computed by the monitoring station from a baseline moisture
established in the monitoring station. In one embodiment, the
baseline moisture is computed at least in part as an average of
moisture readings from a number of moisture sensors. In one
embodiment, the baseline moisture is computed at least in part as a
time average of moisture readings from a number of moisture
sensors. In one embodiment, the baseline moisture is computed at
least in part as a time average of moisture readings from a
moisture sensor. In one embodiment, the baseline moisture is
computed at least in part as the lesser of a maximum moisture
reading an average of a number of moisture readings.
[0097] In one embodiment, the sensor unit 102 reports moisture
readings in response to a query by the monitoring station 113. In
one embodiment, the sensor unit 102 reports moisture readings at
regular intervals. In one embodiment, a moisture interval is
provided to the sensor unit 102 by the monitoring station 113.
[0098] In one embodiment, the calculation of conditions for fungus
growth is comparing moisture readings from one or more moisture
sensors to the baseline (or reference) moisture. In one embodiment,
the comparison is based on comparing the moisture readings to a
percentage (e.g., typically a percentage greater than 100%) of the
baseline value. In one embodiment, the comparison is based on
comparing the moisture readings to a specified delta value above
the reference moisture. In one embodiment, the calculation of
likelihood of conditions for fungus growth is based on a time
history of moisture readings, such that the longer the favorable
conditions exist, the greater the likelihood of fungus growth. In
one embodiment, relatively high moisture readings over a period of
time indicate a higher likelihood of fungus growth than relatively
high moisture readings for short periods of time. In one
embodiment, a relatively sudden increase in moisture as compared to
a baseline or reference moisture is reported by the monitoring
station 113 as a possibility of a water leak. If the relatively
high moisture reading continues over time then the relatively high
moisture is reported by the monitoring station 113 as possibly
being a water leak and/or an area likely to have fungus growth or
water damage.
[0099] Temperatures relatively more favorable to fungus growth
increase the likelihood of fungus growth. In one embodiment,
temperature measurements from the building areas are also used in
the fungus grown-likelihood calculations. In one embodiment, a
threshold value for likelihood of fungus growth is computed at
least in part as a function of temperature, such that temperatures
relatively more favorable to fungus growth result in a relatively
lower threshold than temperatures relatively less favorable for
fungus growth. In one embodiment, the calculation of a likelihood
of fungus growth depends at least in part on temperature such that
temperatures relatively more favorable to fungus growth indicate a
relatively higher likelihood of fungus growth than temperatures
relatively less favorable for fungus growth. Thus, in one
embodiment, a maximum moisture and/or minimum threshold above a
reference moisture is relatively lower for temperature more
favorable to fungus growth than the maximum moisture and/or minimum
threshold above a reference moisture for temperatures relatively
less favorable to fungus growth.
[0100] In one embodiment, a water flow sensor is provided to the
sensor unit 102. The sensor unit 102 obtains water flow data from
the water flow sensor and provides the water flow data to the
monitoring computer 113. The monitoring computer 113 can then
calculate water usage. Additionally, the monitoring computer can
watch for moisture, by, for example, looking for water flow when
there should be little or no flow. Thus, for example, if the
monitoring computer detects water usage throughout the night, the
monitoring computer can raise an alert indicating that a possible
water leak has occurred.
[0101] In one embodiment, a rain sensor is provided to the
monitoring computer 113 and one or more water shutoff valves are
provided to the monitoring computer 113 to allow the monitoring
computer 113 to shut off the water supply to one or more areas of a
building. If one or more moisture sensors report a relatively rapid
rise in moisture levels when it is not raining, then the monitoring
computer can shut off the water supply to the affected area of the
buildings (on the assumption that the moisture is coming from a
plumbing leak).
[0102] FIG. 9 shows a moisture sensor unit 902 that includes an
impedance sensor 901 provided to an impedance probe 903. The sensor
unit 902 is one embodiment of the sensor units 102 or 802 wherein
the sensor 201 is configured as an impedance sensor 901. The
impedance sensor 901 measures the impedance of the probe 903. In
one embodiment, the impedance sensor 901 measures a resistance of
the probe 903. In one embodiment, the impedance sensor 901 measures
an AC resistance of the probe 903. In one embodiment, the impedance
sensor 901 measures an AC reactance of the probe 903. The impedance
sensor 901 receives a control input from the controller 202 and
provides output data to the controller 202.
[0103] The impedance of most building materials varies as the
moisture content of the building material changes. Typically, most
building materials (e.g., concrete, drywall, plaster, wood, etc.)
have a relatively high impedance when dry, and the impedance goes
down as the moisture level increases. Thus, one convenient way to
measure the moisture content of many building materials is to
measure the impedance of a probe provided to the building
material.
[0104] If only the DC resistance is desired, then the probe is
provided in direct electrical contact with the building material.
If the AC impedance is desired, then the probe can be provided in
direct electrical contact with the building material or the probe
can be capacitively coupled to the building material through a
dielectric.
[0105] The probe is typically provided to the building material
when the material is dry. The impedance sensor measures the
impedance of the probe at specified intervals. In one embodiment, a
change in the impedance is reported by the sensor unit 902 to the
monitoring system 113 as a possible increase in moisture
content.
[0106] In one embodiment, the measured impedance data, the
electrical characteristics of the probe, and the type of building
material to which the probe is attached are provided to the
monitoring system 113 to allow the monitoring system 113 to compute
a moisture content value from the impedance data.
[0107] In one embodiment, a threshold value (as described above) is
provided to the sensor unit 902 and the sensor unit reports
impedance data when the measured impedance values cross the
threshold. In one embodiment, the threshold is an upper threshold,
and the impedance data is reported when the measured impedance
values exceed the threshold. In one embodiment, the threshold is a
lower threshold, and the impedance data is reported when the
measured impedance values fall below the threshold. In one
embodiment, the threshold is configured as an inner range. In one
embodiment, the threshold is configured as an outer range. In one
embodiment, a threshold is provided for the magnitude of the
impedance. In one embodiment, a threshold is provided for the real
part of the impedance (e.g., the resistance). In one embodiment, a
threshold is provided for the imaginary part of the impedance
(e.g., the reactance).
[0108] For example, drywall (gypsum) and/or plaster have a
relatively high impedance with dry and the impedance drops as the
moisture content increases. In one embodiment, the sensor unit 902
reports impedance data to the monitoring system 113 whenever the
impedance measured by the impedance sensor 1002 drops by a
specified amount. In one embodiment, the sensor unit 902 reports
impedance data to the monitoring system 113 whenever the impedance
measured by the impedance sensor 1002 drops by a specified amount,
where the specified amount is specified according to the type of
material the probe 1001 is attached to.
[0109] In one embodiment, the sensor unit 902 reports impedance
data to the monitoring system 113 at specified intervals and
whenever the impedance measured by the impedance sensor 1002 drops
by a specified amount. The monitoring system 113 establishes a
"dry" impedance value by recording the highest impedance reported
by the sensor unit 902.
[0110] FIG. 10 shows an impedance sensor 1002 (corresponding to the
impedance sensor 902 from FIG. 9) provided to an impedance probe
1001 configured as a pair of conductive strips 1008, 1009.
Optionally, in one embodiment, two or more pins 1010, 1011 are
provided to the conductive strips 1008, 1009. In one embodiment,
when the probe 1001 is installed, the pins 1010, 1011 are inserted
into the building material in order to provide better electrical
contact with the building material. The pins 1010, 1011 can be
configured as sharp pins attached to the strips 1008, 1009, nails
and/or staples driven through the strips 1008, 1009, etc.
[0111] In response to the control input from the controller 202,
the impedance sensor measures the impedance of the probe 1001. In
one embodiment, the expected impedance values for wet and moist
conditions are determined from the type of building material and
the characteristics of the probe 1001 (e.g., length, number of
pins, etc.).
[0112] FIG. 11 is a schematic of an impedance sensor 1002
configured to measure impedance by using a voltage source 1904 and
a current sensor 1105. The voltage source provides a voltage
between the conductors 1008, 1009, and the current sensor 1105 then
measures the current through the probe. The impedance is then
calculated by using Ohm's law. In one embodiment, the controller
202 controls the voltage produced by the voltage source 1104. In
one embodiment, the voltage source 1104 is a DC source. In one
embodiment, the voltage source 1104 is an AC source. In one
embodiment, the controller 202 controls the frequency and/or phase
of the voltage source 1104. In one embodiment, the current sensor
1105 measures magnitude of the current through the current through
the probe 1001. In one embodiment, the current sensor 1105 measures
magnitude and phase of the current through the current through the
probe 1001.
[0113] FIG. 12 is a schematic of an impedance sensor 1002
configured to measure impedance by using a current source 1204 and
a voltage sensor 1205. The current source 1204 provides a current
through the conductors 1008, 1009, and the voltage sensor 1205 then
measures the voltage across the probe 1001. The impedance is then
calculated by using Ohm's law. In one embodiment, the controller
202 controls the current produced by the current source 1204. In
one embodiment, the current source 1204 is a DC source. In one
embodiment, the current source 1204 is an AC source. In one
embodiment, the controller 202 controls the frequency and/or phase
of the current source 1204. In one embodiment, the voltage sensor
1205 measures magnitude of the current through the voltage across
the probe 1001. In one embodiment, the current sensor 1205 measures
magnitude and phase of the voltage across the current through the
probe 1001.
[0114] FIG. 13 is a schematic of an impedance sensor 1002
configured to measure impedance using an impedance bridge that
includes impedances 1301-1303 in three legs of the bridge, and the
probe is provided to the fourth leg of the bridge. The control
input is provided to a voltage source that drives the bridge and to
a module 1310 that measures the impedance across the bridge. In one
embodiment, the impedance 1303 is fixed. In one embodiment, the
impedance 1303 is varied by the control module 1310. In one
embodiment, the impedance 1303 is fixed. In one embodiment, the
impedance 1303 is varied by the control module 1310 in response to
the control input. The impedance of across the probe 1001 is then
calculated as known in the art by using the known impedances
1301-1303 and the voltage across the bridge.
[0115] FIG. 14 shows a moisture sensor that includes a
time/frequency domain impedance sensor 1402 provided to the
impedance probe 1001. In one embodiment, the time-frequency domain
impedance sensor 1402 uses time-domain and/or frequency domain
measurement techniques to measure the impedance properties along
the impedance probe 1001. In one embodiment, the time-frequency
domain impedance sensor 1402 uses time-domain measurement
techniques to measure the impedance properties along the impedance
probe 1001 by sending a relatively short pulse of energy along the
impedance probe 1001 and measuring the reflections of the energy
pulse. In one embodiment, the time-frequency domain impedance
sensor 1402 is configured as a time-domain reflectometer. In one
embodiment, the time-frequency domain impedance sensor 1402
measures the impedance of the impedance probe 1001 at various
frequencies, and then uses Fourier transform techniques to
transform the measurements from the frequency domain into the time
domain. In one embodiment, the time-domain data are used to
identify regions along the impedance probe 1001 that are relatively
more moist.
[0116] FIG. 15 is a plot showing an example output of the
time-frequency domain impedance sensor 1402 when a relatively small
damp area 1502 is detected. When the impedance probe 1001 is
provided to a building material that has a smaller impedance when
moist, the impedance of the impedance probe 1001 is smaller in the
region 1502 and thus the impedance probe 1001 produces a reflection
corresponding to the region 1502. By way of example, FIG. 15
includes a graph 1530 showing the reduced resistance corresponding
to the region 1502.
[0117] FIG. 16 is a plot showing an example output of the
time-frequency domain impedance sensor 1402 when a relatively
larger damp area 1602 is detected. When the impedance probe 1001 is
provided to a building material that has a smaller impedance when
moist, the impedance of the impedance probe 1001 is smaller in the
region 1502 and thus, the impedance probe 1001 produces a
reflection corresponding to the region 1001. By way of example,
FIG. 16 includes a graph 1630 showing the reduced resistance
corresponding to the region 1502. Comparison of the graphs 1530 and
1630 shows that the time/frequency domain impedance sensor 1402 can
be used to provide an indication of the location, size, and
severity of the moist area. The location of the moist area is
indicated by the location of the moist area along the impedance
probe 1001 (where time can be converted into a distance along the
probe according to the speed of propagation of an electrical signal
along the probe). The size of the moist area is indicated by the
size of the region of lower impedance along the impedance probe
1001. The amount of moisture in the building material at different
points along the impedance probe 1001 is computed from the measured
impedance at various points along the impedance probe 1001 and
knowledge of the properties of the building material provided to
the impedance probe.
[0118] In one embodiment, the time/frequency impedance sensor 1402
is configured according to the schematics shown in FIGS. 11-13
where the respective sources (voltage and/or current sources) are
configured as AC (Alternating Current) sources or sources that
produce a time-domain and/or frequency-domain waveform.
[0119] FIG. 17 is a schematic of one embodiment of the
time/frequency domain impedance sensor 1402 configured as a pulse
reflectometer having a pulse generator 1705, a diplexer switch
1703, and a sampler 1704. A timing generator 1701 is controlled by
the control input and provides control outputs to the pulse
generator 1705, the diplexer switch 1703, and the sampler 1704. The
diplexer switch 1703 is typically an electronic switch configured
using solid-state electronic elements to provide high speed and
high reliability.
[0120] In a transmit mode, the timing generator places the diplexer
switch 1703 in a "transmit position" (as shown), and instructs the
pulse generator 1705 to provide a pulse of relatively-short time
duration (e.g., implses, chirps, frequency pulses, etc) to the
diplexer switch 1703. The diplexer switch 1703 provides the pulse
to the impedance probe 1001. The timing generator then switches the
diplexer switch 1703 to a "receive position" wherein when return
pulse (or pulses) from the impedance probe 1001 are provided to the
sampler 1704. The sampler 1704. The sampler provides sampled data
from the impedance probe 1001 to the controller 202.
[0121] In one embodiment, the moisture sensor unit 902 is
configured as an adjustable-threshold moisture sensor that computes
a threshold level. In one embodiment, the threshold is computed as
an average of a number of sensor measurements. In one embodiment,
the average value is a relatively long-term average. In one
embodiment, the average is a time-weighted average wherein recent
sensor readings used in the averaging process are weighted
differently than less recent sensor readings. In one embodiment,
more recent sensor readings are weighted relatively more heavily
than less recent sensor readings. In one embodiment, more recent
sensor readings are weighted relatively less heavily than less
recent sensor readings. The average is used to set the threshold
level. When the moisture sensor readings rise above the threshold
level, the moisture sensor indicates a notice condition. In one
embodiment, the moisture sensor indicates a notice condition when
the moisture sensor reading rises above the threshold value for a
specified period of time. In one embodiment, the moisture sensor
indicates a notice condition when a statistical number of sensor
readings (e.g., 3 of 2, 5 of 3, 10 of 7, etc.) are above the
threshold level. In one embodiment, the moisture sensor unit 902
indicates various levels of alarm (e.g., warning, alert, alarm)
based on how far above the threshold the moisture sensor reading
has risen.
[0122] In one embodiment, the moisture sensor unit 902 computes the
notice level according to how far the moisture sensor readings have
risen above the threshold and how rapidly the moisture sensor
readings have risen or how long the moisture reading have been
elevated. A relatively fast rate of rise may be indicative of a
relatively serious leak and/or a relatively large volume of water
that could lead to water damage. An area that has been moist (even
slightly moist) for a period of time may be indicative of long-term
damage due to molds, fungus, rotting, etc. For example, for
purposes of explanation, the level of readings and the rate of rise
can be quantified as low, medium, and high. The combination of
sensor reading level and rate of rise then can be show as a table,
as show in Table 1. Tables 1 and 2 provide examples and is provided
by way of explanation, not limitation.
TABLE-US-00001 TABLE 1 Sensor Reading Level (as compared to the
threshold) Rate of Rise High Warning Alarm Alarm Medium Notice
Warning Alarm Low Notice Warning Alarm Low Medium High
TABLE-US-00002 TABLE 2 Sensor Reading Level (as compared to the
threshold) Length of Time Long Alarm Alarm Alarm Medium Warning
Warning Alarm Short Notice Warning Alarm Low Medium High
[0123] One of ordinary skill in the art will recognize that the
notice level N can be expressed as an equation N=f(l, v, r, t),
where l is the threshold level, v is the moisture sensor reading, r
is the rate of rise, and t is the length of time of the moisture
sensor reading. In embodiments where the size of the moist area can
be measured (as described, for example, in connection with FIGS.
13-17), then the size of the moist area can also be included in the
above equation and/or in the above tables. In one embodiment, the
moisture sensor reading v and/or the rate of rise r are lowpass
filtered in order to reduce the effects of noise in the moisture
sensor readings. In one embodiment, the threshold is computed by
lowpass filtering the moisture sensor readings v using a filter
with a relatively low cutoff frequency. A filter with a relatively
low cutoff frequency produces a relatively long-term averaging
effect. In one embodiment, separate thresholds are computed for the
moisture sensor reading and for the rate of rise.
[0124] In one embodiment, a calibration procedure period is
provided when the moisture sensor unit 902 is powered up. During
the calibration period, the moisture sensor data values from the
moisture sensor 201 are used to compute the threshold value, but
the moisture sensor does not compute notices, warnings, alarms,
etc., until the calibration period is complete. In one embodiment,
the moisture sensor unit 902 uses a fixed (e.g., pre-programmed)
threshold value to compute notices, warnings, and alarms during the
calibration period and then uses the adjustable threshold value
once the calibration period has ended.
[0125] In one embodiment, the moisture sensor unit 902 determines
that a failure of the moisture sensor 201 has occurred when the
adjustable threshold value exceeds a maximum adjustable threshold
value. In one embodiment, the moisture sensor unit 902 determines
that a failure of the moisture sensor 201 has occurred when the
adjustable threshold value falls below a minimum adjustable
threshold value. The moisture sensor unit 902 can report such
failure of the moisture sensor 201 to the base unit 112.
[0126] In one embodiment, the moisture sensor unit 902 obtains a
number of sensor data readings from the moisture sensor 201 and
computes the threshold value as a weighted average using a weight
vector. The weight vector weights some sensor data readings
relatively more than other sensor data readings.
[0127] In one embodiment, the moisture sensor unit 902 obtains a
number of sensor data readings from the moisture sensor unit 201
and filters the moisture sensor data readings and calculates the
threshold value from the filtered sensor data readings. In one
embodiment, the moisture sensor unit applies a lowpass filter. In
one embodiment, the moisture sensor unit 201 uses a Kalman filter
to remove unwanted components from the moisture sensor data
readings. In one embodiment, the moisture sensor unit 201 discards
sensor data readings that are "outliers" (e.g., too far above or
too far below a normative value). In this manner, the moisture
sensor unit 902 can compute the threshold value even in the
presence of noisy sensor data.
[0128] In one embodiment, the moisture sensor unit 902 indicates a
notice condition (e.g., alert, warning, alarm) when the threshold
value changes too rapidly. In one embodiment, the moisture sensor
unit 902 indicates a notice condition (e.g., alert, warning, alarm)
when the threshold value exceeds a specified maximum value. In one
embodiment, the moisture sensor unit 902 indicates a notice
condition (e.g., alert, warning, alarm) when the threshold value
falls below a specified minimum value.
[0129] In one embodiment, the moisture sensor unit 902 adjusts one
or more operating parameters of the moisture sensor 201 according
the threshold value. Thus, for example, in the example of a
moisture sensor, the moisture sensor unit 201 can adjust the
voltage (or current) provided to the moisture probe.
[0130] FIG. 18 is a rear view showing one embodiment of the
impedance probe 1001 configured as a molding system 1800. The
molding system 1800 includes linear conductors 1801 and 1802
provided substantially along the length of a molding 1805. The
molding 1805 can be configured as a typical decorative molding,
such as, for example, a baseboard molding, door-jamb molding, crown
molding, wainscot molding, etc. In one embodiment, the conductors
1801, 1802 are relatively smooth and configured to be capacitively
coupled to a building material. In one capacitive coupling
embodiment, the conductors are covered by a relatively thin layer
of dielectric. In one embodiment, a plurality of sharp pins (e.g.,
pins 1803, 1804) are provide to electrically connect the conductors
1801, 1802 pierce into a wall or other building structure when the
molding 1805 is attached to the wall (or structure). In one
embodiment, the conductors 1801, 1802 and the optional pins (e.g.,
the pins 1803, 1804) are provided to the molding 1805 during
manufacture. As with conventional molding, moldings according to
the molding system 1800 are purchased, cut to length, and attached
to a building by nails, glue, staples, screws, etc.
[0131] In one embodiment, connector pins 1808 and 1809 are provided
to the conductors 1801 and 1802 respectively. The optional
connector pins 1808, 1809 extend through to the front of the
molding 1805 to provide electrical connection to sensor unit 802
provided to the front of the molding 1805, as shown in FIG. 19.
[0132] FIG. 20 shows the impedance probe 1001 configured as a
relatively flexible tape 2000. In the tape 2000, the linear
conductors 1801 and 1802 are provided to a dielectric substrate
2001 (e.g., plastic, mylar, nylon, etc.). In one embodiment, the
conductors 1801, 1802 are relatively smooth and configured to be
capacitively coupled to a building material. In one capacitive
coupling embodiment, the conductors are covered by a relatively
thin layer of dielectric. In one embodiment, the tape 2000 is
attached to the desired building material by an adhesive. In one
embodiment, the tape 2000 is attached to the desired building
material by a plurality of staples (or nails) driven through the
conductors 1801 and 1802 so as to provide electrical connection
between the conductors and the building material.
[0133] In one embodiment, a plurality of sharp pins (e.g., pins
1803, 1804) are provide to electrically connect the conductors
1801, 1802 pierce into a wall or other building structure when the
molding 1805 is attached to the wall (or structure). In one
embodiment, an adhesive layer with a peel-off protective cover 2002
is provide to the back of the substrate. The adhesive can be used
to attach the tape 2002 to a molding (or other building material)
before the molding is installed.
[0134] As shown in FIG. 21, an adhesive and a peel-off layer 2101
can also (either along with the adhesive and peel-off 2002 or in
the alternative) be installed on the front of the tape 2000 to
allow the tape 2000 to be installed before any covering of molding.
Thus, the tape 2000 can also be installed to studs before drywall
is installed, installed between studs, installed to flooring,
attached to the inner surfaces of outer walls, etc.
[0135] FIG. 22 shows one installation of the moisture sensor unit
902 to the impedance probe tape 2000 provided between a wall 2201
and a molding 2209. The sensor unit 902 is mounted to the wall and
the tape 2000 is configured to extend past the end of the molding
2209 and under the sensor unit 902 (between the wall and the sensor
unit 902). In one embodiment, a plurality of spikes or pins 2210
are provided to the sensor unit 902 to allow the sensor unit to
make electrical contact with the conductors 1801, 1802 in the tape
2000.
[0136] FIG. 23 shows an alternative installation of the moisture
sensor unit 902 to the impedance probe tape 2000 provided between
the wall 2201 and the molding 2209. In FIG. 23, the tape 2000 is
configured to extend past the end of the molding 2209 and is
wrapped around the end of the molding 2209 and onto the face of the
molding 2209. The sensor unit 902 is mounted to the face of the
molding with a portion of the tape 2000 between the sensor unit and
the face of the molding. In one embodiment, one or more conductive
pads 2310 are provided on the back of the sensor unit 902 to allow
the sensor unit to make electrical contact with the conductors
1801, 1802 in the tape 2000 (and/or with the pins 1803, 1804).
[0137] FIG. 24 shows one example of an installation of the
impedance probe tape 2000 wrapped around a corner. In FIG. 24 a
first piece 2402 of impedance probe tape 2000 is mounted between a
first section of wall 2401 and a first molding 2409. A second piece
2403 of impedance probe tape 2000 is mounted between a second
section of wall 2411 and a second molding 2410. A portion of the
first piece 2402 extends past the end of the molding 2409, wraps
around the corner between the walls 2401 and 2411, and extends
between the molding 2410 and the wall 2411. The piece 2402 overlaps
the piece 2403 in a region 2404. Pins 1803, 1804 on the piece 2402
make electrical contact with the conductors 1801, 1802 on the piece
2403.
[0138] FIG. 25 shows one example of an installation of two shorter
pieces of the impedance probe tape 2000 installed under a
relatively long molding. In FIG. 25 a first piece 2503 of impedance
probe tape 2000 is mounted between a wall 2501 and a molding 2509.
A second piece 2502 of impedance probe tape 2000 is mounted between
the wall 2501 and the molding 2509 such that a portion of the first
piece 2503 overlaps a second piece 2502 in an overlap region. Pins
1803, 1804 on the piece 2502 make electrical contact with the
conductors 1801, 1802 on the piece 2501.
[0139] FIG. 26 shows a self-test unit 2602 for use in connection
with the moisture sensor unit 902. The self-test unit 2602 is
similar to the moisture sensor unit 902 and includes the antenna
204, the transceiver 203, the controller 202, and the power source
206. A control input from the controller 202 is provided to a
testing module 2610. The testing module 2610 includes a test
impedance 2611 and an electronically-controlled switch 2612. The
switch 2612 is configured to provide the test impedance 2611 to the
impedance probe 903 when the switch 2612 is activated by the
control input. In one embodiment, the control input can also be
used to vary the impedance Z of the test impedance 2611. In one
embodiment, the monitoring system 113 sends instructions to the
self-test unit 2602 to control the impedance Z of the test
impedance 2611.
[0140] When instructed, the self-test unit 2602 connects the test
impedance 2611 to the impedance probe 903. The moisture sensor 902,
also provided to the impedance probe 903, can then be used to
measure the impedance of the impedance probe. The moisture sensor
902 can expect to measure the an impedance corresponding to the
combination of the impedance Z and the impedance of the probe just
before or after the self-test unit provided the test impedance Z to
the probe 903. Thus, for example, in one embodiment, the sensor
unit 902 is be provided to one end of the impedance probe tape 2000
and the self-test unit 2602 is provided at an opposite end of the
impedance probe tape 2000 to facilitate testing of the tape 2000
and/or to facilitate testing of the moisture sensor unit 902.
[0141] It will be evident to those skilled in the art that the
invention is not limited to the details of the foregoing
illustrated embodiments and that the present invention may be
embodied in other specific forms without departing from the spirit
or essential attributed thereof, furthermore, various omissions,
substitutions and changes may be made without departing from the
spirit of the inventions. For example, although specific
embodiments are described in terms of the 900 MHz frequency band,
one of ordinary skill in the art will recognize that frequency
bands above and below 900 MHz can be used as well. The wireless
system can be configured to operate on one or more frequency bands,
such as, for example, the HF band, the VHF band, the UHF band, the
Microwave band, the Millimeter wave band, etc. One of ordinary
skill in the art will further recognize that techniques other than
spread spectrum can also be used and/or can be used instead of
spread spectrum. The modulation use is not limited to any
particular modulation method, such that modulation scheme used can
be, for example, frequency modulation, phase modulation, amplitude
modulation, combinations thereof, etc. The foregoing description of
the embodiments is, therefore, to be considered in all respects as
illustrative and not restrictive, with the scope of the invention
being delineated by the appended claims and their equivalents.
* * * * *