U.S. patent application number 16/384454 was filed with the patent office on 2020-10-15 for determining available battery current in a portable electronic device.
The applicant listed for this patent is MOTOROLA SOLUTIONS, INC.. Invention is credited to Javier Alfaro, Peter J. Bartels, Hugo Garcia, George S. Hanna, Liang Xu.
Application Number | 20200326376 16/384454 |
Document ID | / |
Family ID | 1000004006780 |
Filed Date | 2020-10-15 |
United States Patent
Application |
20200326376 |
Kind Code |
A1 |
Bartels; Peter J. ; et
al. |
October 15, 2020 |
DETERMINING AVAILABLE BATTERY CURRENT IN A PORTABLE ELECTRONIC
DEVICE
Abstract
Systems and methods for determining available current for a
battery in a portable electronic device. One method includes, in
response to determining that a received current level of an
auxiliary supply rail is equal to or below a predetermined
threshold, acquiring a plurality of unloaded voltages for the
battery and calculating an unloaded voltage based on the unloaded
voltages. The method includes activating a switchable load coupled
between the battery and ground, acquiring a plurality of loaded
voltages for the battery, and calculating a loaded voltage based on
the loaded voltages. The method includes calculating an impedance
for the battery based on the unloaded and loaded voltages and an
impedance for the switchable load. The method includes determining
a current budget based on the impedance, a minimum operating
voltage, and a maximum allowable current draw, and adjusting an
operating parameter of the portable electronic device based on the
current budget.
Inventors: |
Bartels; Peter J.;
(Loxahatchee, FL) ; Alfaro; Javier; (Miami,
FL) ; Garcia; Hugo; (Miami Springs, FL) ;
Hanna; George S.; (Miami, FL) ; Xu; Liang;
(Weston, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MOTOROLA SOLUTIONS, INC. |
Chicago |
IL |
US |
|
|
Family ID: |
1000004006780 |
Appl. No.: |
16/384454 |
Filed: |
April 15, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 7/0063 20130101;
G01R 31/389 20190101; G01R 31/3647 20190101 |
International
Class: |
G01R 31/36 20060101
G01R031/36; H02J 7/00 20060101 H02J007/00; G01R 31/389 20060101
G01R031/389 |
Claims
1. A system for determining available current for a battery in a
portable electronic device, the system comprising: an auxiliary
supply rail coupled to the battery; a switchable load coupled
between the battery and a ground; a current sensor configured to
sense a current level of the auxiliary supply rail; a voltage
sensor configured to measure a voltage of the battery; and an
electronic processor coupled to the switchable load, the current
sensor, and the voltage sensor, wherein the electronic processor is
configured to receive, from the current sensor, the current level;
and in response to determining that the received current level is
equal to or below a predetermined threshold: acquire, from the
voltage sensor, a plurality of unloaded voltage measurements for
the battery; calculate, based on the plurality of unloaded voltage
measurements, an unloaded voltage; activate the switchable load;
acquire, from the voltage sensor, a plurality of loaded voltage
measurements for the battery; calculate, based on the plurality of
loaded voltage measurements, a loaded voltage; calculate an
impedance for the battery based on the unloaded voltage, the loaded
voltage, and an impedance for the switchable load; determine a
current budget for the battery based on the impedance, a minimum
operating voltage, and a maximum allowable current draw from the
battery; and adjust an operating parameter of the portable
electronic device based on the current budget.
2. The system for determining available current for a battery in a
portable electronic device of claim 1, wherein the electronic
processor is further configured to: in response to determining that
the current level is equal to or below the predetermined threshold,
initialize an unloaded voltage counter; and acquire a plurality of
unloaded voltage measurements by: a) determining whether the
current level is above the predetermined threshold; b) when the
current level is not above the predetermined threshold, taking an
unloaded voltage measurement, incrementing the unloaded voltage
counter, and adding the unloaded voltage measurement to an unloaded
voltage sum; and c) repeating steps a and b until the unloaded
voltage counter is equal to a desired quantity.
3. The system for determining available current for a battery in a
portable electronic device of claim 2, wherein the electronic
processor is configured to, when the current level is above the
predetermined threshold, discard the unloaded voltage
measurement.
4. The system for determining available current for a battery in a
portable electronic device of claim 1, wherein the electronic
processor is further configured to: in response to determining that
the current level is equal to or below the predetermined threshold,
initialize a loaded voltage counter; and acquire a plurality of
loaded voltage measurements by: a) determining whether the current
level is above the predetermined threshold; b) when the current
level is not above the predetermined threshold, taking a loaded
voltage measurement, incrementing the loaded voltage counter, and
adding the loaded voltage measurement to a loaded voltage sum; and
c) repeating steps a and b until the loaded voltage counter is
equal to a desired quantity.
5. The system for determining available current for a battery in a
portable electronic device of claim 4, wherein the electronic
processor is configured to, when the current level is above the
predetermined threshold, discard the loaded voltage
measurement.
6. The system for determining available current for a battery in a
portable electronic device of claim 1, further comprising: a
digital-to-analog converter coupled to the electronic processor;
wherein the auxiliary supply rail includes a current sensing
resistor; wherein the current sensor includes an amplifier coupled
to the current sensing resistor and an analog comparator coupled to
the amplifier and the digital-to-analog converter; wherein the
amplifier is configured to provide an amplified voltage to the
analog comparator; wherein the electronic processor is configured
to control the digital-to-analog converter to provide a reference
voltage to the analog comparator; and wherein the analog comparator
is configured to output a low current level signal when the
amplified voltage is less than the reference voltage.
7. The system for determining available current for a battery in a
portable electronic device of claim 1, wherein the electronic
processor is further configured to: determine a first standard
deviation for the plurality of unloaded voltage measurements; when
the first standard deviation exceeds a first threshold, discard the
plurality of unloaded voltage measurements; determine a second
standard deviation for the plurality of loaded voltage
measurements; and when the second standard deviation exceeds a
second threshold, discard the plurality of loaded voltage
measurements.
8. The system for determining available current for a battery in a
portable electronic device of claim 1, wherein the electronic
processor is further configured to: determine whether a time period
between calculating the unloaded voltage and calculating the loaded
voltage exceeds a correlation threshold; and when the time period
exceeds the correlation threshold, discard the unloaded voltage and
the loaded voltage.
9. The system for determining available current for a battery in a
portable electronic device of claim 1, wherein the switchable load
includes a load power resistor and a field effect transistor; and
the electronic processor is configured to activate the switchable
load by applying a gate voltage to the field effect transistor,
causing the field effect transistor to couple the battery to the
ground via the load power resistor.
10. The system for determining available current for a battery in a
portable electronic device of claim 1, wherein the voltage sensor
is an analog-to-digital converter.
11. The system for determining available current for a battery in a
portable electronic device of claim 1, wherein the electronic
processor is configured to adjust an operating parameter for the
portable electronic device by adjusting at least one selected from
the group consisting of a transmit abort threshold, a transmit
inhibit threshold, an audio peak current, a processor operating
mode, and a radio status.
12. A method for determining available current for a battery in a
portable electronic device, the method comprising: receiving, from
a current sensor, a current level of an auxiliary supply rail; and
in response to determining that the received current level is equal
to or below a predetermined threshold: acquiring, from a voltage
sensor configured to measure a voltage of the battery, a plurality
of unloaded voltage measurements for the battery; calculating, with
an electronic processor, an unloaded voltage based on the plurality
of unloaded voltage measurements; activating, with the electronic
processor, a switchable load coupled between the battery and a
ground; acquiring, from the voltage sensor, a plurality of loaded
voltage measurements for the battery; calculating, with the
electronic processor, a loaded voltage based on the plurality of
loaded voltage measurements; calculating, with the electronic
processor, an impedance for the battery based on the unloaded
voltage, the loaded voltage, and an impedance for the switchable
load; determining a current budget for the battery based on the
impedance, a minimum operating voltage, and a maximum allowable
current draw from the battery; and adjusting an operating parameter
of the portable electronic device based on the current budget.
13. The method for determining available current for a battery in a
portable electronic device of claim 12, further comprising: in
response to determining that the current level is equal to or below
the predetermined threshold, initializing an unloaded voltage
counter; wherein acquiring a plurality of unloaded voltage
measurements includes: a) taking an unloaded voltage measurement;
b) determining whether the current level is above the predetermined
threshold; c) when the current level is not above the predetermined
threshold, incrementing the unloaded voltage counter, and adding
the unloaded voltage measurement to an unloaded voltage sum; and d)
repeating steps a-c until the unloaded voltage counter is equal to
a desired quantity.
14. The method for determining available current for a battery in a
portable electronic device of claim 13, further comprising: when
the current level is above the predetermined threshold, discard the
unloaded voltage measurement.
15. The method for determining available current for a battery in a
portable electronic device of claim 12, further comprising: in
response to determining that the current level is equal to or below
the predetermined threshold, initializing a loaded voltage counter;
wherein acquiring a plurality of loaded voltage measurements
includes: a) taking a loaded voltage measurement; b) determining
whether the current level is above the predetermined threshold; c)
when the current level is not above the predetermined threshold,
incrementing the loaded voltage counter, and adding the loaded
voltage measurement to a loaded voltage sum; and d) repeating steps
a-c until the loaded voltage counter is equal to a desired
quantity.
16. The method for determining available current for a battery in a
portable electronic device of claim 15, further comprising: when
the current level is above the predetermined threshold, discard the
loaded voltage measurement.
17. The method for determining available current for a battery in a
portable electronic device of claim 12, further comprising:
controlling, with the electronic processor, a digital-to-analog
converter to provide a reference voltage to an analog comparator;
providing an amplified voltage to the analog comparator with an
amplifier coupled to a current sensing resistor of the auxiliary
supply rail; and outputting, with the analog comparator, a low
current level signal when the amplified voltage is less than the
reference voltage.
18. The method for determining available current for a battery in a
portable electronic device of claim 12, further comprising:
determining a first standard deviation for the plurality of
unloaded voltage measurements; when the first standard deviation
exceeds a first threshold, discarding the plurality of unloaded
voltage measurements determining a second standard deviation for
the plurality of loaded voltage measurements; and when the second
standard deviation exceeds a second threshold, discarding the
plurality of loaded voltage measurements.
19. The method for determining available current for a battery in a
portable electronic device of claim 12, further comprising:
determining whether a time period between calculating the unloaded
voltage and calculating the loaded voltage exceeds a correlation
threshold; and when the time period exceeds the correlation
threshold, discarding the unloaded voltage and the loaded
voltage.
20. The method for determining available current for a battery in a
portable electronic device of claim 12, wherein adjusting an
operating parameter for the portable electronic device includes
adjusting at least one selected from the group consisting of a
transmit abort threshold, a transmit inhibit threshold, an audio
peak current, a processor operating mode, and a radio status.
21. A system for determining available current for a battery in a
portable electronic device, the system comprising: an auxiliary
supply rail coupled to the battery; a switchable load coupled
between the battery and a ground; a current sensor configured to
sense a current level of the auxiliary supply rail; a voltage
sensor configured to measure a voltage of the battery; and an
electronic processor coupled to the switchable load, the current
sensor, and the voltage sensor, wherein the electronic processor is
configured to receive, from the current sensor, the current level;
and in response to determining that the received current level is
equal to or below a predetermined threshold: in response to
determining that an unloaded voltage interval timer has expired,
acquire, from the voltage sensor, a unloaded voltage measurement
for the battery; determine a maximum unloaded voltage measurement
for the battery based on the unloaded voltage measurement and a
plurality of unloaded voltage measurements; in response to
determining that a high current event delay timer and a loaded
voltage interval timer have expired, activate the switchable load
and begin a switchable load activation timer; in response to
determining that the switchable load activation timer has expired,
acquire, from the voltage sensor, a loaded voltage measurement for
the battery; calculate an impedance for the battery based on the
unloaded voltage, the loaded voltage, and an impedance for the
switchable load; determine a current budget for the battery based
on the impedance, a minimum operating voltage, and a maximum
allowable current draw from the battery; and adjust an operating
parameter of the portable electronic device based on the current
budget.
22. The system for determining available current for a battery in a
portable electronic device of claim 21, wherein the plurality of
unloaded voltage measurements is stored in an array having a
maximum length; and the electronic processor is configured to
determine a maximum unloaded voltage measurement for the battery
by: in response to determining that a current length for the array
is equal to the maximum length, dropping the oldest of the
plurality of unloaded voltage measurements from the array and
adding the unloaded voltage measurement to the array; and selecting
the unloaded voltage measurement having the highest value of the
unloaded voltage measurements in the array.
23. A method for determining available current for a battery in a
portable electronic device, the system comprising: receiving, from
a current sensor, a current level of an auxiliary supply rail; and
in response to determining that the received current level is equal
to or below a predetermined threshold: in response to determining
that an unloaded voltage interval timer has expired, acquiring,
from a voltage sensor configured to measure a voltage of the
battery, a unloaded voltage measurement for the battery;
determining a maximum unloaded voltage measurement for the battery
based on the unloaded voltage measurement and a plurality of
unloaded voltage measurements; in response to determining that a
high current event delay timer and a loaded voltage interval timer
have expired, activating a switchable load coupled between the
battery and a ground and beginning a switchable load activation
timer; in response to determining that the switchable load
activation timer has expired, acquiring, from the voltage sensor, a
loaded voltage measurement for the battery; calculating an
impedance for the battery based on the unloaded voltage, the loaded
voltage, and an impedance for the switchable load; determining a
current budget for the battery based on the impedance, a minimum
operating voltage, and a maximum allowable current draw from the
battery; and adjusting an operating parameter of the portable
electronic device based on the current budget.
Description
BACKGROUND OF THE INVENTION
[0001] Portable electronic devices, for example, two-way radios,
cellular telephones, and converged devices, are powered by
batteries. A battery is able to power a portable electronic device
for a limited time before it must be replaced or recharged. The
battery's remaining power determines for how long and in what ways
a device is able to operate. As a consequence, the control systems
of portable devices are sometimes designed to monitor the battery
to determine its remaining power. As the battery's power is drawn
down or replaced, its power level is reported to a user of the
device. The battery's power level may also be used by the control
systems to determine what features of the device are available for
use (for example, based on those features' power requirements),
whether to shut down the device to prevent adverse effects caused
by a low battery, and the like.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0002] The accompanying figures, where like reference numerals
refer to identical or functionally similar elements throughout the
separate views, together with the detailed description below, are
incorporated in and form part of the specification, and serve to
further illustrate embodiments of concepts that include the claimed
invention, and explain various principles and advantages of those
embodiments.
[0003] FIG. 1 is a schematic diagram of a portable electronic
device, in accordance with some embodiments.
[0004] FIGS. 2A-2B illustrate a flowchart of a method for
determining available current for a battery in the portable
electronic device of FIG. 1, in accordance with some
embodiments.
[0005] FIG. 3 is a chart illustrating the operation of the portable
electronic device of FIG. 1, in accordance with some
embodiments.
[0006] FIG. 4 is a chart illustrating voltage measurements taken
using the method of FIGS. 2A and 2B, in accordance with some
embodiments.
[0007] FIGS. 5A-5B present charts illustrating unloaded battery
voltage measurements showing a voltage drop and rise before,
during, and after a transmit event, in accordance with some
embodiments.
[0008] FIGS. 6A-6B illustrate a flowchart of a method for
determining available current for a battery in the portable
electronic device of FIG. 1, in accordance with some
embodiments.
[0009] Skilled artisans will appreciate that elements in the
figures are illustrated for simplicity and clarity and have not
necessarily been drawn to scale. For example, the dimensions of
some of the elements in the figures may be exaggerated relative to
other elements to help to improve understanding of embodiments of
the present invention.
[0010] The apparatus and method components have been represented
where appropriate by conventional symbols in the drawings, showing
only those specific details that are pertinent to understanding the
embodiments of the present invention so as not to obscure the
disclosure with details that will be readily apparent to those of
ordinary skill in the art having the benefit of the description
herein.
DETAILED DESCRIPTION OF THE INVENTION
[0011] A portable electronic device with multiple systems, for
example, a converged device having both land mobile radio and
cellular systems, operates using multiple modems and processors.
The device monitors its battery's power level. The device's control
systems measure the battery's voltage, and calculate an available
current for the battery using the voltage measurements. However, as
the device operates, the modems, processors, and other electronic
components of the device operate to draw current from the battery
at various times. For example, a microprocessor and camera may
operate to record and process a video stream, a short-range
wireless modem may exchange data transmissions with an access
point, or an LTE modem may place a cellular telephone call. Some of
these components draw enough current while operating to cause a
"voltage slump" in the battery. A voltage slump is a temporarily
low voltage condition in the battery that does not reflect the true
condition of the battery.
[0012] A voltage measurement taken during a voltage slump provides
an incorrect voltage for the battery. Incorrect voltage
measurements lead to false available battery current estimates that
are artificially low. In turn, the device may take unnecessary
actions to reduce power usage based on an inaccurate available
battery current estimate. For example, the device may inhibit or
abort certain functions to preserve battery power or prevent
adverse effects caused by attempting to operate the device with a
low battery. The device may report premature low battery
indications, or inconsistent power readings, prompting device users
to become dissatisfied with what they perceive to be an
inconsistent or insufficient battery life.
[0013] Current methods are unable to consistently accommodate for
voltage slumps when estimating available battery current. For
example, because inter-processor communications are too slow, it is
difficult for a master processor to instantaneously know the
operating state for all other components. In addition, waiting for
components to finish high-current operations or taking repeated
measurements delays updating the battery status. Delays in updating
battery status degrade the user experience. Directly measuring
current with a resistor can shorten battery life and introduces
parasitic resistances, which further impact the measurements.
Finally, coulomb counters require multiple measurements, which
could miss current spikes and delay status updates. Accordingly,
embodiments presented herein provide, among other things, systems
and methods for determining available current for a battery in a
portable electronic device.
[0014] One example embodiment provides a system for determining
available current for a battery in a portable electronic device.
The system includes an auxiliary supply rail coupled to the
battery, a switchable load coupled between the battery and a
ground, a current sensor configured to sense a current level of the
auxiliary supply rail, a voltage sensor configured to measure a
voltage of the battery, and an electronic processor coupled to the
switchable load, the current sensor, and the voltage sensor. The
electronic processor is configured to receive, from the current
sensor, the current level. The electronic processor is configured
to, in response to determining that the received current level is
equal to or below a predetermined threshold, acquire, from the
voltage sensor, a plurality of unloaded voltage measurements for
the battery. The electronic processor is configured to calculate,
based on the plurality of unloaded voltage measurements, an
unloaded voltage. The electronic processor is configured to
activate the switchable load. The electronic processor is
configured to acquire, from the voltage sensor, a plurality of
loaded voltage measurements for the battery. The electronic
processor is configured to calculate, based on the plurality of
loaded voltage measurements, a loaded voltage. The electronic
processor is configured to calculate an impedance for the battery
based on the unloaded voltage, the loaded voltage, and an impedance
for the switchable load. The electronic processor is configured to
determine a current budget for the battery based on the impedance,
a minimum operating voltage, and a maximum allowable current draw
from the battery. The electronic processor is configured to adjust
an operating parameter of the portable electronic device based on
the current budget.
[0015] Another example embodiment provides a method for determining
available current for a battery in a portable electronic device.
The method includes receiving, from a current sensor, a current
level of an auxiliary supply rail. The method includes, in response
to determining that the received current level is equal to or below
a predetermined threshold, acquiring, from a voltage sensor
configured to measure a voltage of the battery, a plurality of
unloaded voltage measurements for the battery. The method includes
calculating, with an electronic processor, an unloaded voltage
based on the plurality of unloaded voltage measurements. The method
includes activating, with the electronic processor, a switchable
load coupled between the battery and a ground. The method includes
acquiring, from the voltage sensor, a plurality of loaded voltage
measurements for the battery. The method includes calculating, with
the electronic processor, a loaded voltage based on the plurality
of loaded voltage measurements. The method includes calculating,
with the electronic processor, an impedance for the battery based
on the unloaded voltage, the loaded voltage, and an impedance for
the switchable load. The method includes determining a current
budget for the battery based on the impedance, a minimum operating
voltage, and a maximum allowable current draw from the battery. The
method includes adjusting an operating parameter of the portable
electronic device based on the current budget.
[0016] Another example embodiment provides a system for determining
available current for a battery in a portable electronic device.
The system includes an auxiliary supply rail coupled to the
battery, a switchable load coupled between the battery and a
ground, a current sensor configured to sense a current level of the
auxiliary supply rail, a voltage sensor configured to measure a
voltage of the battery, and an electronic processor coupled to the
switchable load, the current sensor, and the voltage sensor. The
electronic processor is configured to receive, from the current
sensor, the current level. The electronic processor is configured
to, in response to determining that the received current level is
equal to or below a predetermined threshold and in response to
determining that an unloaded voltage interval timer has expired,
acquire, from the voltage sensor, a unloaded voltage measurement
for the battery. The electronic processor is configured to
determine a maximum unloaded voltage measurement for the battery
based on the unloaded voltage measurement and a plurality of
unloaded voltage measurements. The electronic processor is
configured to, in response to determining that a high current event
delay timer and a loaded voltage interval timer have expired,
activate the switchable load and begin a switchable load activation
timer. The electronic processor is configured to, in response to
determining that the switchable load activation timer has expired,
acquire, from the voltage sensor, a loaded voltage measurement for
the battery. The electronic processor is configured to calculate an
impedance for the battery based on the unloaded voltage, the loaded
voltage, and an impedance for the switchable load. The electronic
processor is configured to determine a current budget for the
battery based on the impedance, a minimum operating voltage, and a
maximum allowable current draw from the battery. The electronic
processor is configured to adjust an operating parameter of the
portable electronic device based on the current budget.
[0017] Another example embodiment provides a method for determining
available current for a battery in a portable electronic device.
The method includes receiving from a current sensor, a current
level of an auxiliary supply rail. The method includes, in response
to determining that the received current level is equal to or below
a predetermined threshold and in response to determining that an
unloaded voltage interval timer has expired, acquiring, from a
voltage sensor configured to measure a voltage of the battery, a
unloaded voltage measurement for the battery. The method includes
determining a maximum unloaded voltage measurement for the battery
based on the unloaded voltage measurement and a plurality of
unloaded voltage measurements. The method includes, in response to
determining that a high current event delay timer and a loaded
voltage interval timer have expired, activating a switchable load
coupled between the battery and a ground and beginning a switchable
load activation timer. The method includes, in response to
determining that the switchable load activation timer has expired,
acquiring, from the voltage sensor, a loaded voltage measurement
for the battery. The method includes calculating an impedance for
the battery based on the unloaded voltage, the loaded voltage, and
an impedance for the switchable load. The method includes
determining a current budget for the battery based on the
impedance, a minimum operating voltage, and a maximum allowable
current draw from the battery. The method includes adjusting an
operating parameter of the portable electronic device based on the
current budget.
[0018] For ease of description, some or all of the example systems
presented herein are illustrated with a single exemplar of each of
its component parts. Some examples may not describe or illustrate
all components of the systems. Other example embodiments may
include more or fewer of each of the illustrated components, may
combine some components, or may include additional or alternative
components.
[0019] FIG. 1 is a diagram of an example portable electronic device
100. As illustrated in FIG. 1, the example portable electronic
device 100 is a converged device, which incorporates hardware and
software elements of a smart telephone and a portable two-way
radio, as described herein. In other embodiments, the portable
electronic device 100 may be another type of portable or mobile
electronic device containing software and hardware enabling it to
operate as described herein.
[0020] In the embodiment illustrated, the portable electronic
device 100 includes an electronic processor 102, a memory 104, a
battery 106, a constant power load 108, a land mobile radio (LMR)
subsystem 110, an application processing (AP) subsystem 112, a
voltage sensor 114, a current sensor 116, a switchable load 118,
and a digital-to-analog converter 120. The illustrated components
of FIG. 1, along with other various modules and components are
coupled to each other by or through one or more control or data
buses that enable communication therebetween. The use of control
and data buses for the interconnection between and exchange of
information among the various modules and components would be
apparent to a person skilled in the art in view of the description
provided herein. The portable electronic device 100 may include
various digital and analog components, which for brevity are not
described herein and which may be implemented in hardware,
software, or a combination of both.
[0021] The electronic processor 102 obtains and provides
information (for example, to and from the memory 104, the voltage
sensor 114, the current sensor 116, and the digital-to-analog
converter 120). The electronic processor 102 processes the
information by executing one or more software instructions or
modules, capable of being stored, for example, in a random access
memory ("RAM") area of the memory 104 or a read only memory ("ROM")
of the memory 104 or another non-transitory computer readable
medium (not shown). The software can include firmware, one or more
applications, program data, filters, rules, one or more program
modules, and other executable instructions. The electronic
processor 102 is configured to retrieve from the memory 104 and
execute, among other things, software related to the control
processes and methods described herein.
[0022] The battery 106 includes one or more battery cells (not
shown) for providing power to the portable electronic device 100,
including to the land mobile radio (LMR) subsystem 110 (for
example, via a main supply rail 121) and the application processing
(AP) subsystem 112 (for example, via an auxiliary supply rail 123).
In some embodiments, the battery 106 is a rechargeable lithium ion
battery. The battery 106 can be connected or disconnected from the
power rails of the portable electronic device 100 using a radio
switch 122. As illustrated in FIG. 1, the battery 106 provides
power to the application processing subsystem 112 via the constant
power load 108 and the auxiliary supply rail 123. In some
embodiments, the constant power load 108 is a DC-to-DC buck
regulator. The constant power load 108 energizes the auxiliary
supply rail 123, which is coupled to the application processing
subsystem 112.
[0023] The land mobile radio subsystem 110 includes electronic
components (not shown) for transmitting and receiving land mobile
radio signals (for example, transceivers, amplifiers, filters,
oscillators, baseband processors, and the like). A land mobile
radio system is a communication system that provides mission
critical functionality, for example push-to-talk functionality,
high audio functionality, and other high current inducing
functionality, for public safety communications. Such systems may
operate in the range of 136-870 Mhz and may generate high radiated
power (for example, in the range of 1.5-6.5 watts), depending on
the frequency band of operation.
[0024] In some embodiments, the application processing subsystem
112 includes electronic components (not shown) for providing smart
telephone functionality to users of the portable electronic device
100. In some embodiments, the application processing subsystem 112
includes hardware and software for transmitting and receiving
cellular (for example, long term evolution (LTE)) radio signals,
short-range wireless signals (for example, Bluetooth.TM.,
Wi-Fi.TM., NFC, and the like). The application processing subsystem
112 also includes one or more processors for executing operating
systems, applications, digital signal processing, and other
computing or communications functions.
[0025] As described in more detail below, the electronic processor
102, is able to determine the available current for the battery 106
using, among other variables, voltage measurements received from
the voltage sensor 114. In some embodiments, the voltage sensor 114
is an analog-to-digital converter, which converts the analog
voltage for the battery (B+, measured from the main battery supply
rail 121) into a digital value that represents the magnitude of the
voltage.
[0026] The land mobile radio subsystem 110 typically operates to
provide half-duplex communications (that is, it is either
transmitting or receiving). As a consequence, the effect of the
land mobile radio subsystem 110 on the voltage of the battery 106
is predictable. However, the application processing subsystem 112
performs multiple functions simultaneously. The various
transmitters and other electronic components draw electric current
at varying levels from the battery 106, which can generate voltage
slumps in an unpredictable way. As described in more detail below,
in some embodiments, the electronic processor 102 is configured to
take into account the voltage slumps caused by the application
processing subsystem 112 when measuring the voltage of the battery
106.
[0027] Because voltage slumps are caused by increased current draw,
the electronic processor 102 uses the current sensor 116 to sense
the current being drawn by the application processing subsystem
112. The current sensor 116 includes a current sensing resistor
124, an amplifier 126, and a comparator 128. The current sensing
resistor 124 is coupled in series with the auxiliary supply rail
123. As current is drawn through the auxiliary supply rail 123, it
causes a voltage drop across the current sensing resistor 124. The
amplifier 126 is coupled to the current sensing resistor and the
comparator 128. The amplifier 126 outputs a voltage proportional to
the voltage drop across the current sensing resistor 124. In some
embodiments, the amplifier 126 is an instrumentation amplifier. The
comparator 128 receives the output from the amplifier 126, and
compares it to a reference voltage provided by the
digital-to-analog converter 120. The electronic processor 102
digitally controls the digital-to-analog converter 120 to provide
an analog reference voltage to the comparator 128. In some
embodiments, the reference voltage (for example, 80 millivolts) is
determined based on the idle current draw of the application
processing subsystem 112 and how much error is acceptable. The
higher the reference voltage value, the higher the current draw of
the application processing subsystem 112 can be before tripping the
comparator 128.
[0028] The comparator 128 is an analog comparator configured to
output a low signal (for example, near zero volts) when the output
from the amplifier 126 is at or below the reference voltage, and to
output a high signal (for example, 5 volts) when the output from
the amplifier 126 exceeds the reference voltage.
[0029] As described in detail below, the electronic processor 102,
is able to determine the available current for the battery 106
using, among other variables, the impedance for the battery
(R.sub.Bat). For ease of explanation, the impedance 130 for the
battery 106 is represented conceptually in FIG. 1. Likewise, the
radio load 132 (R.sub.Radio), which represents the current drawn by
the portable communication device 100, is also represented
conceptually in FIG. 1. As described in detail below, the
electronic processor 102, also uses a loaded voltage for the
battery 106 to determine the available current for the battery 106.
The loaded voltage is measured by pulling the battery 106 to ground
133 using the switchable load 118. The switchable load 118 includes
a load power resistor 134 and a switch 136. In the example
illustrated in FIG. 1, the switch 136 is a field-effect transistor.
The electronic processor 102 uses the switchable load 118 to
intentionally change the battery 106 loading by a known fixed
amount. The electronic processor 102 activates the switchable load
118 by applying a gate voltage to the field-effect transistor,
causing the field-effect transistor to couple the battery 106 to
ground 133 via the load power resistor 134. In other embodiments,
the switch 136 may be any suitable electronic switch. In some
embodiments, the load power resistor 134 is a 24 ohm resistor. The
value is dependent on the load resister power specifications and
the characteristics of the battery. The longer the switchable load
118 is on, the higher the value has to be in order to meet the
power specifications. The higher the power rating of the load power
resistor 134, the lower its resistance value can be. The resistance
of the load power resistor 134 affects the current drawn when
taking a loaded voltage measurement, as described herein.
Accordingly, a lower resistance value improves battery life.
[0030] FIGS. 2A and 2B illustrate an example method 200 for
determining available current for a battery 106. As an example, the
method 200 is described as being performed by the portable
electronic device 100 and, in particular, the electronic processor
102.
[0031] At block 202, the electronic processor 102 receives, from
the current sensor 116, a current level for the auxiliary supply
rail 123. In some embodiments, the current level is a current level
signal provided by the comparator 128. For example, the electronic
processor 102 receives a low current level signal when the
amplified voltage is equal to or below the reference voltage, and a
high current level signal when the amplified voltage is less than
the reference voltage. The current level signal is represented as
ACMP1 in FIGS. 2A and 2B. As noted above, ACMP1 is the output
signal of the comparator 128 comparing a voltage proportional to
the current in the application processing subsystem 112 to a
reference voltage provided by the electronic processor 102 via the
digital-to-analog converter 120.
[0032] In some embodiments, in response to determining that the
received current level is equal to or below a predetermined
threshold (at block 204), the electronic processor initializes (at
block 206) variables, including an unloaded voltage counter
(N.sub.unloaded), a loaded voltage counter (N.sub.loaded), an
unloaded voltage sum (V.sub.unloaded_sum), and a loaded voltage sum
(V.sub.load_sum). The unloaded voltage counter tracks how many
unloaded voltage measurements have been taken. The loaded voltage
counter tracks how many loaded voltage measurements have been
taken. The unloaded voltage sum is the sum of the unloaded voltage
measurements. The loaded voltage sum is the sum of the loaded
voltage measurements. The electronic processor 102 also starts a
timer T to track the passage of time while the method 200 is
performed.
[0033] At block 208, the electronic processor 102 acquires, from
the voltage sensor 114, a plurality of unloaded voltage
measurements for the battery 106. For example, at block 210, the
electronic processor 102 determines whether the current level is
below the predetermined threshold (whether ACMP1 is low). When the
current level is below the predetermined threshold, at block 214,
the electronic processor 102 takes an unloaded voltage measurement
(at block 214), increments the unloaded voltage counter (at block
216), and adds the unloaded voltage measurement to the unloaded
voltage sum (at block 218). When the current level is above the
predetermined threshold, the electronic processor 102 discards the
unloaded voltage measurement. At block 220, the electronic
processor 102 compares the unloaded voltage measurement count
(N.sub.unloaded) to a desired quantity of measurements
(count.sub.unloaded). As illustrated in FIGS. 2A and 2B, the
electronic processor 102 continues taking measurements until the
unloaded voltage counter is equal to a desired quantity (at blocks
210-220).
[0034] In some embodiments, when the unloaded voltage measurement
count is equal to the desired quantity, at block 220, the
electronic processor 102 determines a standard deviation for the
plurality of unloaded voltage measurements. At block 222, when the
standard deviation exceeds a threshold, the electronic processor
102 discards the plurality of unloaded voltage measurements (at
block 212).
[0035] At block 224, the electronic processor 102 calculates, based
on the plurality of unloaded voltage measurements, an unloaded
voltage. In some embodiments, the unloaded voltage is the average
of the plurality of unloaded voltage measurements
(V.sub.unloaded_avg). For example,
V.sub.unloaded_avg=.SIGMA..sub.NV.sub.N/N, where N is the unloaded
voltage measurement count for the plurality of unloaded voltage
measurements.
[0036] At block 226, the electronic processor 102 activates the
switchable load 118, for example, by applying a gate voltage to a
field effect transistor.
[0037] At block 228, the electronic processor 102 acquires, from
the voltage sensor 114, a plurality of loaded voltage measurements
for the battery 106. For example, at block 230, the electronic
processor 102 determines whether the current level is below the
predetermined threshold for example, (whether ACMP1 is low). When
the current level is below the predetermined threshold, at block
232, the electronic processor 102 takes a loaded voltage
measurement (at block 232), increments the loaded voltage counter
(at block 234), and adds the loaded voltage measurement to the
loaded voltage sum (at block 236). When the current level is above
the predetermined threshold, the electronic processor 102 discards
the loaded voltage measurement. At block 220, the electronic
processor 102 compares the loaded voltage measurement count
(N.sub.loaded) to a desired quantity of measurements
(count.sub.loaded). As illustrated in FIGS. 2A and 2B, the
electronic processor 102 continues taking measurements until the
loaded voltage counter is equal to a desired quantity (at blocks
230-238).
[0038] In some embodiments, the desired quantity (for both loaded
and unloaded voltage measurements) is six. The higher the quantity
of data points, the longer it takes to take the measurements and
the more likely it is that the measurements may be interrupted by
the comparator due to a current spike in the application processing
subsystem 112. In some embodiments, the desired quantity of
measurements is determined by balancing between getting a good
average for more consistent results and not taking so long that it
decreases the number of times that a clean measurement may be
obtained.
[0039] In some embodiments, when the loaded voltage measurement
count is equal to the desired quantity, at block 240, the
electronic processor 102 determines a standard deviation for the
plurality of loaded voltage measurements. At block 242, when the
standard deviation exceeds a threshold, the electronic processor
102 discards the plurality of loaded voltage measurements (at block
212).
[0040] At block 244, the electronic processor 102 calculates, based
on the plurality of loaded voltage measurements, a loaded voltage.
In some embodiments, the loaded voltage is the average of the
plurality of loaded voltage measurements (V.sub.loaded_avg). For
example, V.sub.loaded_avg=.SIGMA..sub.NV.sub.N/N, where N is the
loaded voltage measurement count for the plurality of loaded
voltage measurements.
[0041] In some embodiments, at block 246, the electronic processor
102 determines whether a time period between calculating the
unloaded voltage and calculating the loaded voltage exceeds a
correlation threshold (for example, five seconds). For example, in
some embodiments, the timer T is a countdown timer and the
electronic processor 102 determines that the time period exceeds
the correlation threshold when the timer T expires. In another
example, the timer T is a count up timer, and the electronic
processor 102 determines whether the time period exceeds the
correlation threshold by comparing the elapsed time to the
correlation threshold. When the time period exceeds the correlation
threshold, the loaded and unloaded voltages have been taken too far
apart to provide an accurate estimate of available current. As a
consequence, the electronic processor 102 discards the unloaded
voltage and the loaded voltage (at block 212). In some embodiments,
the correlation threshold is based on the rate of current draw of
the portable electronic device 100 and the rate of voltage drop of
the battery due to this current draw. The higher the current draw
or rate of voltage drop, the lower the correlation threshold should
be.
[0042] At block 248, the electronic processor 102 calculates an
impedance for the battery 106 (R.sub.bat) based on the unloaded
voltage (V.sub.unloaded), the loaded voltage (V.sub.load), and an
impedance for the switchable load (R.sub.load) using the following
equation:
R.sub.bat=R.sub.load*(V.sub.unloaded/V.sub.load-1)
[0043] At block 250, the electronic processor 102 determines a
current budget (I.sub.budget) for the battery 106 based on the
impedance (R.sub.bat), a minimum operating voltage (V.sub.min) for
the portable electronic device, and a maximum allowable current
draw from the battery (I.sub.rated_max) using the following
equation:
I.sub.budget=min(I.sub.rated_max,
[V.sub.unloaded-V.sub.min]/R.sub.bat)
[0044] At block 252, the electronic processor 102 adjusts an
operating parameter of the portable electronic device based on the
current budget. For example, the electronic processor 102 adjusts
operating parameters to reduce the loading of the portable
electronic device (R.sub.Radio) to confine the maximum current draw
to less than the current budget. For example, the electronic
processor 102 may adjust one or more of a transmit abort threshold
(how long a transceiver will transmit before shutting down a
transmission), a transmit inhibit threshold (at what point
transmission will be prevented from starting), an audio peak
current for a loudspeaker, a processor operating mode (for example,
a low power mode), and a radio status (for example, disabling one
or more radios of the application processing subsystem 112).
[0045] FIG. 3 is a chart 300, which illustrates the operation of
the portable electronic device 100 according to the method 200.
Line 302 shows the voltage (B+) for the battery 106 while the land
mobile radio subsystem 110 and the application processing subsystem
112 operate in various states. Line 304 shows the current for the
application processing subsystem 112, compared to the threshold for
a high current level (shown as line 306). Line 308 shows the output
of the comparator 128 in response to the current of the application
processing subsystem 112. A series of voltage measurements 310 are
taken with the switchable load 118 both on and off. As illustrated
in FIG. 3, when the comparator output indicates a high current
condition on the application processing subsystem 112, the data
collected during the high current conditions are ignored.
[0046] FIG. 4 illustrates a chart 400, which shows voltage
measurements taken without using the output of the comparator 128
to check the current level of the application processing subsystem
112, and a chart 402, with shows voltage measurements taken using
the output of the comparator 128 to check the current level of the
application processing subsystem 112. Each chart compares
measurements taken with the voltage sensor 114 to measurements
taken using bench equipment. As illustrated in FIG. 4, using the
method 200 results in a measurement error of between -1% and +5%,
while measurements taken without using the method 200 result in a
measurement error of between -53% and +15%.
[0047] FIG. 5A illustrates a chart 500, showing voltage
measurements for a voltage drop and rise before, during, and after
a transmit event (represented by the line 502), taken while the
device operates at an ambient temperature of 25 degrees Celsius. As
illustrated in the chart 500, the battery voltage takes some period
of time to reach a steady state after a transmit event. Voltage
measurements taken prior to the steady state do not provide
accurate information regarding the unloaded battery voltage,
resulting in false determinations of battery impedance, as noted
herein. To calculate a more accurate battery impedance, the
unloaded voltage measurement after a transmit event should be taken
after the voltage has reached steady state.
[0048] In addition, as ambient temperatures lower, battery
chemistry changes the rate at which its voltage drops and rises
dependent on load magnitude and duration. For example, FIG. 5B
illustrates a chart 504, showing voltage measurements for a voltage
drop and rise before, during, and after a transmit event
(represented by the line 506), taken while the device operates at
an ambient temperature of -30 degrees Celsius. As shown in charts
500 and 504, the battery voltage takes longer to reach steady state
after a transmit event at -30 degrees Celsius than at 25 degrees
Celsius. As a consequence, when the portable electronic device 100
is operated outdoors in colder climes, this may result in a lower
battery impedance calculation than what the device would actually
experience during a constant (non-instantaneous) high current draw
event. Lower battery impedance calculations may result in incorrect
voltage measurements or in a device reset, when inadequate current
mitigation actions are taken.
[0049] FIGS. 6A and 6B illustrate an example method 600 for
determining available current for the battery 106. As an example,
the method 600 is described as being performed by the portable
electronic device 100 and, in particular, the electronic processor
102.
[0050] At block 602, the electronic processor 102 receives, from
the current sensor 116, a current level for the auxiliary supply
rail 123, for example, as described herein with respect to the
method 200. The current level signal is represented as ACMP1 in
FIGS. 6A and 6B. As noted herein, ACMP1 is the output signal of the
comparator 128.
[0051] In some embodiments, the electronic processor initializes
(at block 604) timers, including an unloaded voltage interval timer
(T.sub.unloaded_interval) and a loaded voltage interval timer
(T.sub.loaded_interval). The unloaded voltage interval timer is
used to track how much time has expired since an unloaded voltage
was last measured. The loaded voltage interval timer is used to
track how much time has expired since a loaded voltage was last
measured. As described more particularly below, the timers are used
to set the intervals at which the electronic processor 102 takes
voltage measurements. The intervals are set based on the operating
characteristics of the portable electronic device 100. For example,
a heavily used device draws current more quickly. As a consequence,
longer measurement intervals may lead to artificially high current
budgets because the available current of the battery is drawn down
between measurements. The higher the current draw, the faster the
voltage drops, and the lower the interval should be and vice versa.
In some embodiments, the unloaded voltage interval is two minutes
and the loaded voltage interval is twenty minutes. The loaded
voltage interval is larger than the unloaded voltage interval
because measuring the loaded voltage requires activating the
switchable load 118, which draws current. Doing this too often will
adversely affect battery life.
[0052] In some embodiments, at block 606, the electronic processor
102 deactivates the switchable load 118, for example, by
deasserting a gate voltage to a field effect transistor.
[0053] In some embodiments, in response to determining that the
received current level is equal to or below a predetermined
threshold (for example, 500 ms) (at block 608), the electronic
processor 102 resets a high current event delay timer
(T.sub.high_current_delay). As described more particularly below,
the high current event delay timer is used to track the amount of
time that has passed since a high current event (for example, an
LMR transmission) has occurred. This is based on the
characteristics of the battery and the current draw of the higher
current events. The longer the battery voltage takes to stabilize
after a higher current event, the longer this delay should to be
(for example, as illustrated in FIG. 5A).
[0054] At block 612, the electronic processor 102 determines
whether the unloaded voltage interval timer has expired (for
example, but comparing the elapsed time to a threshold value for
the interval). When the unloaded voltage interval timer has not
expired, the electronic processor 102 continues at block 606. In
response to determining that an unloaded voltage interval timer has
expired (at block 612), the electronic processor 102 acquires, from
the voltage sensor, an unloaded voltage measurement
(V.sub.unloaded) for the battery (at block 614). In some
embodiments, the electronic processor 102 acquires an average
unloaded voltage measurement, as described herein with respect to
the method 200. In some embodiments, the voltage sensor 114 is
configured to periodically take voltage measurements, keep a
rolling average, and provide the average unloaded voltage
measurement to the electronic processor 102 when requested.
[0055] At block 616, the electronic processor determines a maximum
unloaded voltage measurement (V.sub.unloaded_max) for the battery
based on the unloaded voltage measurement and a plurality of
unloaded voltage measurements. In some embodiments, the electronic
processor 102 uses an array (V.sub.unloaded_array) of unloaded
voltage measurements to determine a rolling maximum unloaded
voltage measurement. For example, in some embodiments, the
plurality of unloaded voltage measurements is stored (for example,
in memory 104) in an array having a maximum length
(V.sub.max_array_length). In such embodiments, the electronic
processor 102 receives the unloaded voltage measurement (at block
614), and stores the measurement in the array. Prior to storing a
new measurement, the electronic processor 102 determines whether
the current length of the array is equal to the maximum length
(that is, whether or not the array is full). In some embodiments,
V.sub.max_array_length is set to sixty. In some embodiments, the
maximum length is based on the rate of current draw of the portable
electronic device 100 and the rate of voltage drop of the battery
due to this current draw. The higher the rate of voltage drop, the
lower V.sub.max_array_length should be. This may be determined
based on available system resources because reading data occupies
processor and data buses. The larger the array is, the more
accurate measurement will be. If unloaded voltage is measured too
frequently, it could adversely impact system performance.
[0056] When the array is full, the electronic processor 102 drops
the oldest unloaded voltage measurement from the array and adds the
new unloaded voltage measurement to the array. When the array is
not full, the electronic processor 102 adds the new unloaded
voltage measurement to the array. The electronic processor 102
determines the maximum unloaded voltage by selecting the unloaded
voltage measurement having the highest value from the unloaded
voltage measurements in the array.
[0057] At block 618, because an unloaded voltage has been measured,
the electronic processor resets the unloaded voltage interval
timer.
[0058] In some embodiments, the electronic processor 102 determines
whether a high current event has occurred (e.g., by checking a
constant high current event counter, which is incremented when a
high current event is triggered). When a high current event has
occurred, the electronic processor 102 resets the high current
event delay timer (at block 622) and the constant high current
event counter (at block 624), and continues at block 606.
[0059] When a high current event has not occurred (at block 620),
the electronic processor determines whether the loaded voltage
interval timer (at block 626) and the high current event delay
timer (at block 628) have expired. When either timer has expired,
the electronic processor 102 continues at block 606. As illustrated
in FIGS. 6A and 6B, the electronic processor 102 is either
continuously or periodically monitoring the current level signal
(ACMP1) (for example, at block 630). When the current level signal
indicates low current, the electronic processor 102 continues
executing the method 600. When the current level signal indicates a
high current on the auxiliary supply rail 123, the electronic
processor 102 continues at block 606. Alternatively, or in
addition, the electronic processor 102 uses the value of ACMP1 as a
multiplier when setting the unloaded and loaded voltage values (for
example, at blocks 616 and 638).
[0060] While the current level signal indicates a low current on
the auxiliary supply rail 123, and in response to determining that
both the high current event delay timer and the loaded voltage
interval timer have expired, the electronic processor 102 activates
the switchable load (for example, by applying a gate voltage to a
field effect transistor) and begins a switchable load activation
timer (T.sub.load_on) (at block 632). The switchable load
activation timer tracks the time that passes after the switchable
load is activated. At block 634, the electronic processor 102
determines whether the switchable load activation timer has
expired. When the timer has not expired, the electronic processor
102 continues to check the current level and assert the switchable
load, while waiting for the timer to expire (at blocks 630-634). In
some embodiments, the switchable load activation timer is 500 ms.
This is based on the characteristics of the battery and the current
draw of R.sub.load. The longer the battery voltage takes to
stabilize after R.sub.load is enabled, the longer this delay should
be.
[0061] At block 636, in response to determining that the switchable
load activation timer has expired, the electronic processor 102
acquires, from the voltage sensor, a loaded voltage measurement for
the battery (for example, as described herein with respect to the
method 200).
[0062] At block 644, the electronic processor 102 calculates an
impedance for the battery based on the unloaded voltage, the loaded
voltage, and an impedance for the switchable load, as described
herein with respect to the method 200.
[0063] At block 646, the electronic processor 102 determines a
current budget for the battery based on the impedance, a minimum
operating voltage, and a maximum allowable current draw from the
battery, as described herein with respect to the method 200.
[0064] At block 648, the electronic processor 102 adjusts an
operating parameter of the portable electronic device based on the
current budget, as described herein with respect to the method
200.
[0065] In the foregoing specification, specific embodiments have
been described. However, one of ordinary skill in the art
appreciates that various modifications and changes can be made
without departing from the scope of the invention as set forth in
the claims below. Accordingly, the specification and figures are to
be regarded in an illustrative rather than a restrictive sense, and
all such modifications are intended to be included within the scope
of present teachings.
[0066] The benefits, advantages, solutions to problems, and any
element(s) that may cause any benefit, advantage, or solution to
occur or become more pronounced are not to be construed as a
critical, required, or essential features or elements of any or all
the claims. The invention is defined solely by the appended claims
including any amendments made during the pendency of this
application and all equivalents of those claims as issued.
[0067] Moreover in this document, relational terms such as first
and second, top and bottom, and the like may be used solely to
distinguish one entity or action from another entity or action
without necessarily requiring or implying any actual such
relationship or order between such entities or actions. The terms
"comprises," "comprising," "has," "having," "includes,"
"including," "contains," "containing" or any other variation
thereof, are intended to cover a non-exclusive inclusion, such that
a process, method, article, or apparatus that comprises, has,
includes, contains a list of elements does not include only those
elements but may include other elements not expressly listed or
inherent to such process, method, article, or apparatus. An element
proceeded by "comprises . . . a," "has . . . a," "includes . . .
a," or "contains . . . a" does not, without more constraints,
preclude the existence of additional identical elements in the
process, method, article, or apparatus that comprises, has,
includes, contains the element. The terms "a" and "an" are defined
as one or more unless explicitly stated otherwise herein. The terms
"substantially," "essentially," "approximately," "about" or any
other version thereof, are defined as being close to as understood
by one of ordinary skill in the art, and in one non-limiting
embodiment the term is defined to be within 20%, in another
embodiment within 10%, in another embodiment within 2% and in
another embodiment within 1%. The term "coupled" as used herein is
defined as connected, although not necessarily directly and not
necessarily mechanically. A device or structure that is
"configured" in a certain way is configured in at least that way,
but may also be configured in ways that are not listed.
[0068] It will be appreciated that some embodiments may be
comprised of one or more generic or specialized processors (or
"processing devices") such as microprocessors, digital signal
processors, customized processors and field programmable gate
arrays (FPGAs) and unique stored program instructions (including
both software and firmware) that control the one or more processors
to implement, in conjunction with certain non-processor circuits,
some, most, or all of the functions of the method and/or apparatus
described herein. Alternatively, some or all functions could be
implemented by a state machine that has no stored program
instructions, or in one or more application specific integrated
circuits (ASICs), in which each function or some combinations of
certain of the functions are implemented as custom logic. Of
course, a combination of the two approaches could be used.
[0069] Moreover, an embodiment can be implemented as a
computer-readable storage medium having computer readable code
stored thereon for programming a computer (e.g., comprising a
processor) to perform a method as described and claimed herein.
Examples of such computer-readable storage mediums include, but are
not limited to, a hard disk, a CD-ROM, an optical storage device, a
magnetic storage device, a ROM (Read Only Memory), a PROM
(Programmable Read Only Memory), an EPROM (Erasable Programmable
Read Only Memory), an EEPROM (Electrically Erasable Programmable
Read Only Memory) and a Flash memory. Further, it is expected that
one of ordinary skill, notwithstanding possibly significant effort
and many design choices motivated by, for example, available time,
current technology, and economic considerations, when guided by the
concepts and principles disclosed herein will be readily capable of
generating such software instructions and programs and ICs with
minimal experimentation.
[0070] The Abstract of the Disclosure is provided to allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. In addition,
in the foregoing Detailed Description, it can be seen that various
features are grouped together in various embodiments for the
purpose of streamlining the disclosure. This method of disclosure
is not to be interpreted as reflecting an intention that the
claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter lies in less than all features of a single
disclosed embodiment. Thus the following claims are hereby
incorporated into the Detailed Description, with each claim
standing on its own as a separately claimed subject matter.
* * * * *