Note: Descriptions are shown in the official language in which they were submitted.
CA 02569275 2006-12-13
APPARATUS AND METHOD FOR MONITORING A VARIETY OF RESOURCE
CONSUMPTION METERS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to the field of electrical systems and devices and more
specifically to an apparatus and method for monitoring a variety of resource
consumption
meters.
Discussion of the Prior Art
The ability to measure the operation of a utility meter without physically
altering the
meter itself is of significant importance to the millions of consumers who
would like to
continuously monitor their use of the limited natural resources of our planet,
without the
expense of replacing their existing metering systems with advanced electronic
metering
systems that may be design to only provide usage data to the utility company
themselves, not
the consumer themselves.
One of the most common requirements for monitoring is to count the revolutions
of
the spinning disk in an analog style electricity meter. Existing systems
require installation
inside the electricity meter with close proximity to the disk.
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CA 02569275 2006-12-13
There exists a need for a non-invasive detection system that can function on a
wide
variety of meter types and does not require a high degree of accuracy in
locating the sensor,
and does not require user knowledge of the type of meter they are installing
the system on.
OBJECTS OF THE INVENTION
It is an object of the present invention to overcome the deficiencies noted in
the prior
art.
It is a further object of the present invention to provide an improved
apparatus and
method for non-invasive measurement of a resource consumption meter.
SUMMARY
One embodiment of the invention comprises an apparatus for monitoring a
variety of
resource consumption meters through the use of adaptive illumination,
detection and signal
processing. For this embodiment of the invention, the resource consumption
meter emits a
signal having a frequency relative to the rate of metered resource
consumption. In this
embodiment, the apparatus comprises at least one signal detection means and a
circuit
operatively connected to the signal detection means for the interpretation of
the signal by a
human.
In another embodiment of the invention the apparatus is an optical apparatus
and the
signal emitted by the resource consumption meter is an energy emission
detectable by the
optical apparatus. The energy emission may comprise light in the visible
spectrum, light in
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the invisible spectrum or an energy emission in another part of the electro-
magnetic
spectrum.
In one embodiment of the invention, the apparatus is adapted for a digital
resource
consumption meter that emits a signal directly detectable by an optical
apparatus.
In another embodiment of the invention the apparatus is adapted for an
analogue
resource meter such as one having a spinning disk. In this embodiment there is
a need to
convert the analogue signal, such as the rate of rotation of the spinning
disk, into a signal
detectable by the optical apparatus. In this embodiment the apparatus includes
an energy
emitter to direct energy onto the analogue device, a reflector to direct
energy back from the
analogue device and an energy detector to detect the reflected energy. This
embodiment of
the apparatus may have more than one energy detector.
In one embodiment of the invention there is provided a circuit operatively
connected
to the signal detector. In this embodiment of the invention, the circuit
includes a
discriminator adapted to block input signals having a second frequency lower
than the first
frequency. The second frequency represents spurious energy signals that might
be caused by
sunlight reflecting into the signal detector. Such reflections would occur at
a lower
frequency than the energy reflected by, say, a rotating disk type electrical
metering device.
The discriminator also acts as an amplifier to amplify the first frequency
signal.
In one embodiment of the invention there is provided an apparatus for
monitoring a
resource consumption meter emitting a signal having a first frequency relative
to a rate of
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metered resource consumption, wherein the apparatus comprises: at least one
signal
detection means; and, a circuit operatively connected to the at least one
signal detection
means and adapted for converting detected signals into human readable output
indicative of
the rate of metered resource consumption. The circuit is adapted to provide
three optional
circuit paths representing one of: a sample and hold mode of operation adapted
for an
analogue meter having a moving indicator indicative of resource consumption; a
digitizing
mode of operation; and, an analog to digital mode of operation.
In another embodiment of the invention the sample and hold mode of operation
circuit path comprises an energy emitter adapted to illuminate the moving
indicator with a
plurality of short pulses. Each pulse of the plurality of short pulses is a
fast-rise square wave
pulse having an adjustable period and power. There is also included an energy
detector
adapted to detect reflected energy from the moving indicator during the
defined duration and
an energy emitter pulsing means operatively connected to the energy emitter
and adapted for
providing a plurality of short pulses over the defined duration. A
discriminator is operatively
connected to the energy detector for blocking spurious signals and amplifying
permitted
signals. Signal storage means is operatively connected to the discriminator
for storing a
predetermined number of signals of increasing magnitude over the duration
until fully
charged. The storage means will discharge a discharge signal if exposed to a
predetermined
number of signals that are decreasing in magnitude over the duration. A signal
comparator is
operatively connected to the storage means for receiving the discharge signal
and removing
from the discharge signal an ambient signal to create an output signal. The
comparator
amplifies the output signal. There is also included an analogue to digital
converter adapted
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to receive the analogue output signal and convert it into a digital signal so
that a connected
microprocessor can receive and interpret the digital signal.
In yet another embodiment of the invention the digitizing mode of operation
pathway
comprises an energy emitter adapted to illuminate the moving indicator with a
plurality of
short pulses having a defined duration; an energy detector adapted to detect
reflected energy
from the moving indicator during the defined duration; an energy emitter
pulsing means
operatively connected to the energy emitter and adapted for providing the
plurality of short
pulses over the defined duration; a discriminator operatively connected to the
energy
detector for blocking spurious signals and amplifying output signals; a
digitizing element
adapted for receiving the discriminator output signals and converting the
discriminator
output signals to digital signals. The discriminator output signals are fast
time-varying
signals of a predetermined magnitude and the digitizing element output signals
are input into
a microcontroller for interpretation. The digitizing element produces a
digitizing element
output as long as the predetermined magnitude remains above a predetermined
level.
In one embodiment of the invention the digitizing mode of operation pathway
comprises an energy detector adapted to detect emitted energy from a digital
resource
consumption meter; a discriminator operatively connected to the energy
detector for
blocking spurious signals and amplifying output signals; and, a digitizing
element adapted
for receiving the discriminator output signals and converting the
discriminator output signals
to digital signals. The discriminator output signals are fast time-varying
signals of a
predetermined magnitude and the digitizing element output signals are input
into a
microcontroller for interpretation.
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In yet another embodiment of the invention the analogue to digital mode of
operation
circuit path comprises: a energy emitter adapted to illuminate the moving
indicator with a
plurality of short pulses having a defined duration; an energy detector
adapted to detect
reflected energy from the moving indicator during the defined duration; energy
emitter
pulsing means operatively connected to the energy emitter and adapted for
providing the
plurality of short pulses over the defined duration; a discriminator
operatively connected to
the energy detector for blocking spurious signals and amplifying permitted
signals; an
analogue to digital converter adapted to receive the permitted signals and
convert the
permitted signals to digital signals; and, a microprocessor adapted to receive
and interpret
the digital signals. The energy detector is an energy detector adapted to
detect emitted
energy from a digital resource consumption meter.
In another embodiment of the invention there is provided an apparatus for
monitoring
a resource consumption meter emitting a signal having a first frequency
relative to a rate of
metered resource consumption comprising: an energy emitter adapted for
illuminating an
analogue indicator wherein the analogue indicator is adapted to reflect energy
as the signal to
at least one energy detector. The embodiment includes a circuit operatively
connected to the
at least one energy detector and adapted for generating a signal for
interpretation by a
microprocessor. The circuit is adapted to provide three optional circuit paths
representing
one of: a first path for a sample and hold mode of operation adapted for an
analogue meter
having a moving indicator indicative of resource consumption; a second path
for a digitizing
mode of operation; and, a third path for an analog to digital mode of
operation. In this
embodiment there is provided a methodology of operating the apparatus in a
multi-mode
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format comprising the following steps: selecting an off mode by disabling the
energy eniitter
and said first, second and third paths; selecting a digital resource
consumption meter
detection mode by enabling the first path and disabling the energy emitter,
the second path
and the third path; selecting a digital resource consumption meter detection
mode, wherein
the digital resource consumption meter has a consumption indicator requiring
external
illumination, by enabling the energy eniitter for external illumination and
the first path;
selecting an analogue spinning disk resource consumption meter mode by
enabling the
energy emitter and the first path; selecting an automatic gain control mode by
enabling the
energy emitter, the first path and the third path; selecting a digital
"flashing light" resource
consumption meter mode, wherein the flashing light relates to resource
consumption, by
enabling the second path and disabling the energy emitter, the first and the
third paths;
selecting a digital "flashing light" resource consumption meter mode wherein
the energy
emitter and first path are disabled and the second and third paths are
enabled; selecting a
reflective type resource consumption meter mode wherein the energy emitter is
enabled and
the second path is enabled and the first and third paths are disabled;
selecting a self test mode
wherein the energy emitter is enabled and the second and third paths are
enabled and the first
path is disabled; selecting an automatic meter detection mode wherein the
energy emitter is
enabled and the first, second and third paths are enabled.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and advantages of the invention will
be
apparent from the following more particular description of the preferred
embodiments of the
invention as illustrated in the accompanying drawings in which like reference
characters
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refer to the same parts throughout the different views. The drawings are not
necessarily to
scale, emphasis instead being placed upon illustrating the principles of the
invention.
Figure 1 is a representation of the functional blocks of one embodiment of the
invention.
Figure 1 a is a representation of one operating mode of one embodiment of the
invention.
Figure lb is a representation of another operating mode of one embodiment of
the invention.
Figure lc is a representation of yet another operating mode of one embodiment
of the
invention.
Figure 2 is a representation of an emitted light pulse in the energy vs. time
domain in another
embodiment of the invention.
Figure 3 is a representation of a detected light pulse originating from self-
excitation in the
energy vs. time domain in one embodiment of the invention.
Figure 4 is a representation of a detected light pulse originating externally
to the system in
another embodiment of the invention.
Figure 5 is a representation of a repetitive series of detected pulses and a
tracked signal
related to them in one embodiment of the invention.
Figure 6 is a representation of a longer series of detected pulses, a tracked
signal, and signal
variation in one embodiment of the invention.
Figure 7 is a representation of the modified signal variation from Figure 6.
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DETAILED DESCRIPTION
The Problem
A consumer may wish to monitor the state of a variety of resource consumption
meters at their home or business. These may include electricity, water and
natural gas
meters. Consumer may not know exactly what kind of meter they have. It is
desired to have
an apparatus that can read information from a wide variety of metering systems
in a non-
invasive way while maintaining a high level of adaptability to different meter
types by
enabling or disabling circuitry that may not be needed in every meter
installation.
A preferred embodiment of the invention contains four basic functions that can
be
enabled and disabled to allow a wide variety of meters to be sensed and read.
These meters
produce signals that have a first frequency that is relative to the rate of
metered resource
consumption. Therefore the invention must be able to detect these signals
whether they are
analogue or digital. In addition, the invention may be used to automatically
detect what type
of resource consumption meter system it is installed upon and then select the
correct
operating mode for operation on that system.
The basic functions of the preferred embodiment of the invention are described
in
Table 1.
The Circuit
Referring now to Figure 1, there is shown a block diagram of the apparatus of
one
embodiment of the invention. The apparatus is attached to a resource
consumption meter
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CA 02569275 2006-12-13
(113) that emits a signal having a first frequency that is relative to the
rate of metered
resource consumption. The resource consumption meter may be digital or
analogue and
emits a signal in the form of an energy emission or by changing reflectivity
through a
spinning disk, LCD display or other means. Provided is at least one signal
detection means
to detect the signal from the meter. Also provided is a circuit (100) that is
operatively
connected to the at least one signal detection means and adapted to interpret
the received
signal for a human. In one embodiment the apparatus is an optical apparatus.
The apparatus
is adapted to detect signals either from an analogue resource consumption
meter or a digital
resource consumption meter. Where the resource consumption meter is an
analogue meter,
there is provided an energy emitter (102), such as an infrared light energy
emitter, positioned
such that it can illuminate a means for reflecting the energy, which is part
of the analogue
meter. This is the means by which the analogue signal is converted into an
energy emission
detectable by the signal detection means. For example an analogue meter may
comprise an
indicator such as a needle, dial, and shutter or niirror those changes to
indicate the rate
resource consumption. Therefore, there is also provided means for reflecting
energy from
the indicator to the energy detector (103). When connected to an analogue
resource
consumption meter, the emitter (102) is activated by an emitter signal (101)
received from a
microprocessor (lOla). The emitter signal (101) is also used to enable a
Sample and Hold
Path (105) which is described in detail later. The emitter (102) is not
required on systems
which include an active indication of consumption such as many digital
electricity meters
which will flash their own integrated light source at a rate that varies to
indicate the
parameter being monitored.
Means for signal detection (103) is adapted to receive energy emissions from
the
active indicators as are often found in digital metering apparatus. The means
for signal
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CA 02569275 2006-12-13
detection (103) may also be positioned to receive reflected, transmitted or
transflective
signals from the emitter (102). In one embodiment, there is at least one means
for signal
detection that is positioned to receive the reflected energy emission from the
emitter. In
another embodiment there is more than one means to receive the reflected
energy emission.
The circuit includes a discriminator (104) that allows only rapid changes in
the
detector (103) signal to be amplified. For example, signals that are emitted
and detected at a
first frequency are the desired signals. Signals detected at a second
frequency that is lower
than the first frequency represent spurious and unwanted signals which need to
be
segregated. Such lower frequency signals often represent such anomalies as
sunlight
reflections. Therefore the discriminator provides a combination of low-
frequency blocking
to eliminate the effects that sunlight or other ambient conditions may cause.
The
discriminator also provides amplification of the desired first frequency
signal.
In a preferred embodiment of the apparatus the at least one signal detection
means
operatively connected to the circuit provides for three optional circuit paths
representing one
of a sample and hold mode of operation adapted for analogue meters having a
moving
indicator indicative of resource consumption; a digitized mode of operation;
and, an
analogue to digital mode of operation. These different circuit paths are all
related to the type
of resource consumption meter that the apparatus is connected to and intended
to read. As
indicated in Table 1, one or more circuit pathways can be used at any time.
The Sample and Hold Pathway
Referring to Figure la, in one embodiment of the invention, the Sample and
Hold
Path mode of operation (115) operates in a synchronous fashion with the
emitter (102) and
the energy emitter pulsing means (lOla) that is the microprocessor. This is
significantly
different from signal filter systems normally employed in meter reading
applications. A
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typical signal filter will accumulate signal information in an ongoing basis.
The Sample and
Hold Pathway mode of operation (115) allows signal information to only affect
the output
signal during the short period of time that the emitter (102) is actually
pulsed. In this way
spurious noise which occurs when the emitter is not being pulsed is not
averaged into a final
reading. It would be ignored. A second benefit of this mode of operation is
the fact that it
saves power. A conventional filter-based design requires a continuous stream
of emitter
(102) and detector (103) pulses which are then time-averaged to produce a
final signal.
Reducing the duty-cycle of the emitter would therefore result in a similar
reduction in signal
amplitude and would therefore lower the total signal-to-noise ratio of the
system. Systems
based on filtering tend to use system duty cycles greater than 1%. A system
based on
synchronized sampling can operate at duty-cycles less than 1% while
maintaining a signal-
to-noise ratio that is better than systems operating at much higher duty-cycle
rates.
Combining this with discriminator (104) mentioned earlier produces a superior
total system.
Still referring to Figure 1 a, the signal from the Sample and Hold Path (115)
is stored
in signal storage means such as a capacitor (106) or using a similar voltage-
preserving
storage or memory. The signal storage means is adapted to store a
predetermined number of
signals having increasing magnitudes. The signal storage means (106) is
preferably sized
such that, in the event of a step-function on the received signal, several
pulses from the
Sample and Hold Path (115) are required for the signal storage means (106) to
reach a
steady-state voltage. This provides filtering against noise and reduces large
power transients
that may be caused if the circuit attempted to instantaneously bring the
signal storage means
(106) to a different voltage level. The signal from the signal storage means
(106) is then fed
to a filter (107). The filter (107) determines the magnitude of the ambient
signal in the
circuit. The filter is essentially a very long time constant filter which will
stabilize to the
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CA 02569275 2006-12-13
average signal level of the circuit. The signal from the signal storage means
is also
transmitted to an amplifier (or comparator) (108) which subtracts the ambient
signal from the
detected signal from signal storage means (106). The signal output (109) from
the amplifier
(108) is therefore the difference between the present signal level and the
average signal level
of the system. Due to the long time constants involved, the signal output
(109) is a slowly
time varying signal. This allows the microcontroller and analog-to-digital
converter in the
system (not shown) to sample and interpret the signal in a non-real-time
fashion with
sampling rates that may be orders of magnitude slower than the actual emitter
rates used.
This can result in dramatic power savings. Alternatively, if an additional
comparator was
used with appropriate threshold levels chosen or a microprocessor controlled
threshold, the
output signal (109) may be tied to a digital input of a microcontroller,
further reducing the
need for signal post-processing and software.
The Digitized Pathway
Referring to Figure lb, the output of the discriminator (104) the signal may
also
follow pathway (116) and pass to a digitizing element (110) which will trigger
only when a
fast-time-varying signal is present on the output of the discriminator. The
digitized pathway
comprises an energy detector (103) adapted to detect energy directly from a
digital resource
consumption meter, a discriminator (104) operatively connected to the energy
detector for
blocking spurious signals and amplifying output signals and a digitizing
element (110)
adapted for receiving discriminator output signals and converting them to
digital signals if
the discriminator signals are fast time-varying signals of a predetermined
magnitude. The
output (111) from the element (110) would be connected directly to a
microprocessor input
for processing and subsequent interpretation by a human. This type of fast
signal will also
occur if, for example, the detector (103) senses the infrared output pulse
directly from a
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digital electricity monitor. If the system is also enabling the emitter (102)
then the digital
output (111) would activate each time an emitted pulse was detected. This
provides a useful
self-test feature and can also be used to automatically detect the type of
meter the unit is
installed upon. This is explained in more detail later.
A further aspect of the digitizing element (110) is the ability to digitize
not only the
presence of the fast-time-varying signal, but also the magnitude of such
signal. The digital
output (111) will stay active for a period that is proportional to the
strength of the fast-time-
varying signal pulse itself. When used to detect infrared emitter pulses from
an active
metering system, the active period length will indicate how well aligned the
detector (103) is
to the emitter source. This also works when the system is emitting pulses
using the emitter
(102) and can indicate alignment on the meter (113) itself.
Analog to Digital Pathway
Referring to Figure lc, the output of the discriminator (104) the signal may
also
follow pathway (122). This pathway may comprise an energy emitter (102)
adapted to
illuminate an indicator on an analogue resource consumption meter with a
plurality of short
pulses over a defined period of time. The emitter is not required on systems
that may self-
illuminate such indicator or will produce an emission that can be detected by
a detector that
has an analog output rather than a digital output. The pathway will always
comprise an
energy detector (103) adapted to detect energy from the indicator over the
defined period, a
discriminator (104) operatively connected to the energy detector for blocking
spurious
signals and amplifying permitted signals. An analogue to digital converter
(120) would be
used for converting the signal (112) to a digital signal to a microprocessor
for interpretation
for a human. The microcontroller is adapted to measure the analog voltage at
any time. This
mode of operation can be used to search for asynchronously occurring pulses at
the detector
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CA 02569275 2006-12-13
(103) which would indicate that the unit is installed on an active digital
meter. When used on
an analog meter where the system uses an emitter (102) to generate pulses,
measuring the
peak of the discriminator pulse (104) can be used to measure if the system is
properly
aligned, and to set appropriate automatic gain levels.
Automatic gain may be implemented by voltage controlled gain elements at the
digitizing element (110), or the amplifier (108) or using software methods on
the analog
signal itself. Automatic gain may also be implemented using novel methods such
as:
dynamically changing the power delivered to the emitter (102); by varying the
duty-cycle of
the emitter (102); or by varying the sensitivity of the detector (103).
Referring now to Figure 2, there is shown a representation of an emitted light
pulse in
the energy vs. time domain (200). For simplicity, the emitter (Figure 1, Item
102) would be
enabled for a period of time (202) with a rapid rise time (203) and a constant
power output
(201). This results in a generally square waveform of emitter power. Other
wave shapes may
be used with a variety of advantages. Slower rise times (203) may be employed
to reduce
spurious emissions and noise. The power level (201) may be increased at the
leading edge of
the pulse to compensate for and effectively speed up the slow-response of the
light detector.
Various wave shapes may also be used as a means of further discriminating the
source of the
detected signal to effectively increase signal to noise ratio in the signal.
Referring now to Figure 3, there is shown is a representation of a detected
light pulse
at the output of the discriniinator (104) as shown in Figure 1. This
originates from self-
excitation in the energy vs. time domain (300) when the system is exposed to
an excitation
pulse shown in Figure 2. The ramp-up time (303) will generally have an
exponential shape
due to the response time of the light sensor, system capacitance, inductance
and resistance.
Certain active elements such as amplifiers may also influence the ramp-up
time. The total
CA 02569275 2006-12-13
pulse length (302) will generally be similar to the original excitation signal
but the pulse may
be slightly longer due to ramp-down time (301) caused by many of the same
factors as the
ramp-up time (303). The overall magnitude of the pulse is dependent on many
factors
including, but not limited to, the magnitude of the excitation signal,
reflectivity of the source
and sensitivity of the detector. The responsiveness of the detector (103) and
discriminator
(104) combination shown in Figure 1 would be tuned to the expected excitation
pulse period
which will be used. The pulse period would preferably be less than 100uS and
would occur
at a rate that is preferably greater than 100Hz such that the overall duty-
cycle was less than
1%.
Referring now to Figure 4, there is shown a representation (400) of a detected
light
pulse originating externally to the apparatus such as from a digital meter.
Many metering
systems use an emitted light pulse that is lOmS long (402, not to scale). This
is much larger
than the chosen response time (404) of the detector (103) and discriminator
(104) shown in
Figure 1, which would typically be less than or equal to 100uS. The detected
light pulse will
therefore ramp-up (403) in a way that is similar to a self-excitation pulse,
but after the
response time (404) was exhausted, the signal ramps-down (401) over the
remaining period.
This has several advantages for reading metering systems that have an infrared
output signal.
The primary advantage is that the system will detect externally generated
light pulses
regardless of duration, provided they are longer than 100uS. Even if the
externally generated
light pulses contain modulated data, as some modern meter do, the overall
information burst
will be detected by the system. The second advantage is that the externally
generated pulse is
converted into a fast-time-varying signal which is suitable for triggering the
digitizing
element (110) shown in figure 1.
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CA 02569275 2006-12-13
Refeffing now to Figure 5 there is shown a representation (500) of a
repetitive series
of detected pulses and a tracked signal related to them. The first pulse shown
in the series is
at a lower magnitude than the following three pulses. This would be
representative of a
change in the signal being monitored (Figure 1, Item 113). Two voltage signals
are shown
with respect to time. The signal from the output of the discriminator (104)
shown in Figure 1
is shown as the thick line discriminator signal (501). The Sample and Hold
Path (105) output
shown in figure 1 is shown as the thin line tracking signal (504). A single
received pulse
(502) is shown followed by a period where the excitation is not active (503).
The time
intervals are not shown to scale as the received pulse (502) is typically less
than 1% of the
total period. It can be seen that the tracking signal (504) attempts to follow
the discriminator
signal (501), but it does not follow it instantly; it may take several pulses
before the signals
match (505). There may also be some offset voltage or the signals may be at
different scales
to each other, this is not shown for simplicity reasons, the main feature is
that the signal
stabilizes to a known value with respect to the input signal.
Referring now to Figure 6 there is shown a representation of a longer series
of
detected pulses (600), a tracked signal and signal variation. A slight offset
voltage is shown
between the individual pulses (601) and the tracking signal (602). A sustained
dip (603) in
detected energy will be reflected in the tracking signal. This sustained dip
may be caused by
the black-band of a spinning disk inside an electricity meter. In this case
the dip may be less
than 0.1% of the total signal height because the small change in reflected
energy as a
spinning disk goes by compared to the amount of reflection from the glass
covering the
meter, the metal on the face of the meter, and even cross-talk directly
between the emitter
and detector elements. Therefore this diagram is exaggerating the size of the
dip, which may
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not even be visible with conventional oscilloscopes or to a low resolution
digital to analog
converter system.
Referring now to Figure 7 there is shown representation (700) of the modified
signal
variation from Figure 6. This is the expected output from an amplifier (108)
shown in Figure
1. By removing the average signal level from the present signal level, the
magnitude of the
dip is greatly amplified and is easy to detect either by digital means, or
through the use of an
analog to digital converter and appropriate software threshold methods as are
known in the
art.
Referring again to Table 1 of operating modes, with each mode annotated with
an arbitrary
reference number, a detailed description of each operating mode will be
presented.
Mode 1: Disabled
The system is not emitting or detecting anything. This would be a standby or
off state for the
system.
Mode 2: Not Useful
The excitation source is being operated, but none of the system outputs are
being monitored.
This is not a useful mode during normal operation, but could be used during
system
production testing.
Mode 3: Alternate Digital "Flashing Light" Meter
By enabling only the analog path from the detector, the system has the ability
to
continuously search for light perturbations at the input of the system which
would originate
from an external light source. This can be used to directly measure pulsed
light output from a
digital meter, or it may be used to measure the magnitude of a digital light
pulse. Magnitude
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information may indicate mechanical alignment properties, power consumption
properties,
or other system information.
Mode 4: On/Off Passive Meter
Some meters may use a display device which is dependent on external light. A
Liquid
Crystal Display is a good example of a device that is normally read using
ambient lighting.
Some meter types have a flashing black square, bar graph, or other indicator
that indicates
rate of consumption. Enabling the excitation source allows this indicator to
be read by the
detector as the level of light absorbed by the meter will vary as the
indicator changes. This
variation can then be read by digitizing the detector signal with an analog to
digital converter
using the Analog Path of the system.
Mode 5: Not Useful
By enabling only the Sample and Hold path from the detector, but without
activating the
sample-and-hold element itself through the use of the excitation source, no
useful
information can be gained, with the exception of zero-offset voltages or other
production or
testing information.
Mode 6: Analog Spinning Disk Meter
The most common electricity meter is based on a spinning disk that has a black-
mark on it.
Other meter types such as gas and water may also be read using this mode of
operation. The
excitation source is enabled and the reflected energy at the detector is
sampled and compared
to the average reflected energy. Perturbations in the reflected energy are
amplified and
digitized into the microcontroller. The microcontroller can then count the
disk rotations and
measure the time between rotations to determine power consumption.
Mode 7: See Mode 3 and Mode 5
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This mode effectively encompasses the features of Mode 3, but also has the
uselessness of
Mode 5 and would therefore not be used in normal operation.
Mode 8: Automatic Gain Control
In mode 6 an analog spinning disk is read by enabling the emitter and reading
back
perturbations in the reflected energy. However, if too much energy is being
emitted by the
emitter, then the circuit elements may overload and therefore the
perturbations may not be
seen. Similarly, if the system is poorly mounted resulting in minimal
reflected energy, then
perturbations caused by the black-mark on the disk may not be seen. By
monitoring the
Analog Path either continuously, or occasionally, the actual analog value of
the detected
signal can be read. If this signal is very large, then the excitation energy
can be reduced (or
gain may be reduced) until the signal falls into the normal operating range of
the circuit
elements. Similarly, if the detector signal is too small, then excitation
energy can be
increased (or gain can be increased) to increase reflected energy and attempt
to bring the
signal back into a useable range.
This effectively implements automatic gain based on reflected energy directly,
rather than
guessing at reflected energy by looking only at the Sample-and-Hold path.
Mode 9: Digital "Flashing Light" Meter
A meter type that uses an active display, meaning a display that emits
radiation at a rate that
is proportional with consumption, can be read in this mode. The detector
energy is fed into a
digitizing comparator or similar system that will produce a digital output
when the detector
sees a pulse of light. Many digital meters include an infrared emitter that
pulses for IOmS for
every 1 watt-hour of energy consumed. This mode of operation would be used to
monitor
this infrared light source.
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Embedded digital information may also be read in this mode. For example, some
digital
resource monitors may flash the light to indicate consumption, but will
further modulate the
flashing to indicate other parameters such as power factor or temperature. The
time between
macro pulses may therefore indicate one parameter while the inter-pulse
modulation may
contain additional data.
Mode 10: On/Off Reflective Type
Any meter that contains a highly reflective surface that can be obscured,
tilted or
mechanically moved can be monitored in this mode. The emitter source is used
to flood the
surface to be measured, if the surface is highly reflective, enough of the
emitter energy will
be reflected into the detector to cause the digital output of the system to
activate. If the
surface is not reflective then the digital output will not be active. The
difference between
reflective and non-reflective need to be fairly large, larger than the
differences seen with
standard spinning-disk meters when the black-mark passes the detector.
A reflective LCD with a mirrored back would provide sufficient On/Off
reflectivity to be
monitored using this mode. Needles, peep-holes and pendulums would be other
candidates
for monitoring using this mode.
Mode 11: Alternate Digital "Flashing Light" meter - Automatic Detection
This mode is very similar to Mode 3 with the exception that if the light
source is strong
enough, it would activate the digital output. Using this detection mode would
allow the
system to detect flashing light outputs, and to determine if the signal levels
were high
enough to switch to Mode 9 monitoring only the Digital Output Path, or if the
system should
switch to Mode 3, monitoring only the Analog Output Path.
Mode 12: Self Test Mode
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In this mode the output of the excitation source would be coupled into the
detector using a
highly reflective surface. The Digital Output Path will activate whenever the
excitation
source is switched on, and the Analog Path can be monitored to ensure the
magnitude of the
detected energy meets system expectations.
Mode 13 to 15: Not Useful
These modes are effectively combinations of other system modes and would not
normally be
operated on their own except in calibration, production test or self-test
operations.
Mode 16: Automatic Meter Detection
This is possibly the most useful mode in which the system can operate. When
the system is
mounted on a meter, for example an electricity meter, the system would not
know if it was
mounted to a digital meter with a flashing light output, or an analog meter
with a spinning
disk.
The system would enable all sense paths and the excitation path.
By continuously digitizing the Analog Path using an analog to digital
converter, the system
can look for tell-tale spikes that indicate the detector has received
excitation energy. The
system knows when the excitation source is enabled. Therefore the system can
perform a
simple evaluation on each spike and use that information to determine system
type:
1. If the spike occurs at the same time as the excitation source was enabled,
then it is
likely self-excitation. If the spike is smaller or larger than the previous
spike then
monitor the Sample and Hold Path to determine if the signal changes look like
an
analog spinning disk meter with the black-band traversing the detector.
2. If the spike occurs asynchronously to the excitation source, then the
excitation energy
occurred externally to the system and the system is therefore mounted on some
fornm
of digital meter with an active light output.
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The above monitoring can take place for tens of seconds, minutes, or even
hours with a
certain number of positive identifications, or ratio of meter type being
required before the
system jumps to an operating mode which is optimized for only the detected
meter type. This
would be done primarily to save power.
Although the description above contains much specificity, these should not be
construed as
limiting the scope of the invention but as merely providing illustrations of
some of the
presently preferred embodiments of this invention. Thus the scope of the
invention should
be determined by the appended claims and their legal equivalents.
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