Electricity: battery or capacitor charging or discharging – Battery or cell charging – With detection of current or voltage integral
Reexamination Certificate
2001-02-12
2002-05-07
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
With detection of current or voltage integral
Reexamination Certificate
active
06384578
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to battery-operated wireless communication devices, such as radios, and in particular, to estimating the useful power remaining available in the batteries of such radios.
2. Background of the Invention
Batteries are utilized to power portable radios, such as two-way radios, cell phones, pagers, and the like. It is often necessary to estimate battery voltage during operation of the radio to ensure the radio has sufficient operating power and, more particularly, voltage for proper operation. In some radios, these estimates result in battery voltage levels, which are in turn translated into discrete sets of battery fuel levels which can be associated with fuel “bars” that are displayed on a visual display of the radio.
It is well-known in the art that the voltage of a battery “slumps” according to the load placed on it. Radios are typically not configured to detect a minimum transmit battery voltage (V
tx min
) that corresponds to a maximum or peak current draw during in-slot transmission. However, radios are often able to detect an average in-slot transmit battery voltage (V
in-slot
) and an average out-of-slot transmit battery voltage (V
out-slot
). As used herein, V
in-slot
and V
out-slot
refer to slots or windows of time when the radio transmits data and stays the transmission of data during a transmission mode of operation, respectively. In prior art radios, V
tx min
is estimated by multiplying the difference between V
in-slot
and V
out-slot
by a constant compensation factor (K). The constant compensation factor K is determined empirically from bench measurement and then programmed as a fixed variable in the radio. A typical formula for use in calculating battery voltage levels in both stand-by and transmission modes is represented as follows:
V
tx min
=(
V
out-slot
)−[(
V
out-slot
)−(
V
in-slot
)]*K
where V
out-slot
is assumed to equal a stand-by battery voltage (V
std-by
) and V
tx min
equals the minimum transmit battery voltage.
V
tx min
is then compared against a set of predetermined loaded voltage thresholds to determine the fuel “bars” to be displayed on the visual display of the radio and to estimate the useful power remaining in the battery.
There are two basic problems with the above-described approach. First, V
out-slot
is assumed to equal V
std-by
. This assumption, however, is incorrect since the radio continues to draw power during the out-of-slot transmission mode that it would not draw when in stand-by mode. Specifically, the voltage of the battery while the radio is in stand-by mode will be greater than the voltage of the battery while the radio is in out-of-slot transmission mode. This difference causes the voltage threshold comparison for stand-by mode to need to be adjusted accordingly.
The second shortcoming with the prior art approach arises when V
tx min
is compared to the set of predetermined voltage thresholds which are determined based on the assumption that the radio is operating at substantially full transmission power. However, the more aggressively the radio reduces its transmission power, the more this comparison will be adversely affected. This is especially true when the radio is operating in a GSM mode of operation where the radio more aggressively reduces its transmission power output as a function of the strength of the signal received by the radio.
REFERENCES:
patent: 5155428 (1992-10-01), Kang
patent: 6023150 (2000-02-01), Patino
patent: 6191558 (2000-03-01), Arai et al.
Cole Charles
Patino Joseph
Pence, Jr. William F.
Rodriguez Alexander
Garrett Scott M.
Motorola Inc.
Tibbits Pia
Wong Peter S.
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