Note: Descriptions are shown in the official language in which they were submitted.
20370~
WO 91/02424 PC! /US90/03387
PORTABLE TELEPHOI~JE
WITH POWER SOURCE/~AODE CHANGE DURING CALLS
R~ck~round of the Invention
The present invention is generally related to
radiotelephones, and more particularly to a cellular
15 portable telephone which accommodates a power source
change and corresponding operating mode change during a
- radiotelephone call.
Cellular portable telephones currently have batteries
with capacity for one-half hour of continuous operation. As
20 a result most users typically carry one or more spare
batteries so that they can switch to another battery when
the portable telephone indicates that the battery voltage is
low. However, when the battery is removed during a
cellular telephone call, the call is terminated and the user
25 must redial the call. Interrl~ption of the power source and
termination of a cellular telephone call in process also
occurs when the user plugs the cellular portable telephone
into a vehicle's battery by way of a vehicular adaptor
installed therein, such as a battery eliminator connected to
30 the vehicle's cigarette lighter. For the foregoing reasons,
there is a need for a cellular portable telephone which
accommodates a power source change and corresponding
operating mode change during a cellular telephone call.
- 2n37050
Objects of the Invention
Accordingly, it is an object of the present
invention to provide a unique portable radiotelephone,
which automatically accommodates a power source change
and corresponding operating mode change during a
radiotelephone call.
It is another object of the present invention to
provide a unique portable radiotelephone, which
automatically determines the type of power source
coupled thereto and changes the operating mode of the
portable radiotelephone to correspond thereto.
Summary of the Invention
In accordance with the present invention, there is
provided a method for controlling a radiotelephone call
when changing the power source coupled to a portable
radiotelephone between internal power sources, external
power sources, or internal and external power sources.
The portable radiotelephone has first and second modes
of operation for the internal and external power
sources, respectively. During a radiotelephone call,
pre-selected information identifying the radiotelephone
call is stored. In response to an interruption of the
power source, an indication signal is produced for a
predetermined time interval. Then, the radiotelephone
call corresponding to the stored pre-selected
information is re-entered when the power source is
changed and the indication signal is present. The
portable radiotelephone is operated in the first mode of
operation when the power source is changed to the
internal power source, and in the second mode of
operation when the power source is changed to the
external power source.
Brief Description of the Drawings
Figure 1 is a block diagram of a cellular portable
telephone 100 embodying the present invention.
Figure 2 is a flow chart for the power-up process
~A
- 20~7050
- 2a -
used by microcomputer 104 in Figure 1 for re-entering a
cellular telephone call in progress before a power
source change.
Figure 3 is a flow chart for the process used by
5microcomputer 104 in Figure 1 for storing and updating
specific cellular information during a cellular
telephone call.
Figure 4 is a circuit diagram of timer 400 in
cellular portable telephone 100 in Figure 1.
10Figure 5 is a block diagram of a hands-free adaptor
embodiment of vehicular adaptor 200 in Figure 1.
Figure 6 is a block diagram of a mobile transceiver
adaptor embodiment of vehicular adaptor 200 in Figure 1.
Figure 7 is a block diagram of a battery eliminator
15adaptor embodiment of vehicular adaptor 200 in Figure 1.
- A
.
203705(~
- 3 - CE002 1 7R
Det~iled nesori~tion of the Preferred Fmbo-liment
Referring to Figure 1, there is illustrated a block
diagram o~ a cellular portable telephone 100 embodying the
5 present invention, which automatically accommodates a
power source change during a cellular telephone call
between the portable's battery 300 and another battery 300
or an external power source from vehicular adaptor 200,
such as, for example, a battery eliminator adaptor, a hands-
10 free adaptor, or a mobile transceiver adaptor. In otherembodiments, vehicular adaptor 200 may be a voltage
source coupled to conventional AC line power. Portable
telephone 100 includes cellular radiotelephone transceiver
102 operable in cellular radiotelephone systems,
15 microphone 120 and switchable amplifier 122, speaker 124
and switchable amplifier 126, radio microcomputer 104
with internal RAM storing pertinent cellular telephone call
parameters and ROM 108 storing control software, a power
controller 11 0 including re~ulators coupled to battery 300
20 for generating DC voltages for powering other blocks, a line
conditioner 116 coupled to external power source 119, a
keypad/display microcomputer 1 14 including internal ROM
with control software for controlling display 116 and
keypad 118. Radio microcomputer 104, keypad/display
25 microcomputer 114, and vehicular adaptor 200 are coupled
to and communicate with one another by way of three-wire
data bus 115, which operates as described in U.S. patent
nos. 4,369,516 and 4,616,314.
Blocks 102-126 of portable telephone 100 may
30 be conventional blocks of commercially available portable
radiotelephones, such as, for example, the ~MICROTAC PT~
Cellular Telephone available from Motorola, Inc. The
"MICROTAC PT~ Cellular Telephone is described in further
detail in operators manual no. 68P81150E49. published by
..,
,. ,~
. .~
PCI`/US90/03387
- 4 -
2n37050
and available from Motorola C & E Parts, 1313 East
Algonquin Road, Schaumburg, Illinois 60196.
Vehicular adaptor 200 may likewise be conventional
adaptors for commercially available portable
5 radiotelephones. In the preferred embodiment, vehicular
adaptor 200 may be a battery eliminator adaptor with a
cigarette lighter plug, a hands-free adaptor with regulated
power supply, or a mobile transceiver adaptor with
regulated power supply, all of which couple portable
10 telephone 100 to vehicle battery 500. According to the
present invention, the operating mode of portable telephone
100 automatically changes when it is coupled to or
decoupled from vehicular adaptor 200 during a cellular
telephone call. When coupled to battery 300, portable
15 telephone 100 is in the battery mode, in which, inter alia,
display 116 is disabled by microcomputer 116 when
inactive (no keys of keypad 118 activated) for a
predetermined time for minimizing battery current drain.
Display 116 is re-enabled when keys of keypad 118 are
20 activated. When coupled to baKery eliminator adaptor 200,
portable telephone 100 is in the battery eliminator mode, in
which, inter alia, display 116 is not disabled when inactive
for a predetermined time. When coupled to duplex hands-
free adaptor (DHFA) 200, portable telephone 100 is in the
25 DHFA mode, in which, inter alia, display 116 is not disabled
when inactive for a predetermined time. When coupled to
mobile transceiver adaptor (CVC) 200, portable telephone
100 is in the CVC mode, in which, inter alia, display 116 is
not disabled when inactive for a predetermined time. The
30 foregoing modes of operation of portable telephone 100 are
summarized below in Table 1.
20370~0
WO 91/02424 PCltUS90/03387
TARLF I
Portable Power Display External Amplifiers
Mode Su~p~ Timer D~t~ Rus 1~ ~ 126
Battery Internal Enabled Not used Enabled
Battery Eliminator External Disabled Not used Enabled
Hands-Free External Disabled CMP.Shifted Disabled
High State
Mobile Transceiver External Disabled Us~d Disabled
Portable telephone 100 also includes timer 400 which
may be implemented by individual components as shown in
Figure 4 or which may be a commercially available real-
time clock which has a digital output having a value
indicating the current time and is coupled via diode 427 to
20 back-up battery 424 providing power when battery 300 is
removed. Timer 400 is necessary to prevent attempting to
re-connect a cellular telephone call when more than a
predetermined length of time has elapsed during a power
source change. In this case, the cellular telephone call
25 should not be re-connected since the cellular base site
equipment of the cellular radiotelephone system will
terminate the call automatically on loss of the supervisory
audio tone (SAT) for a predetermined length of time and
may then re-assign the cellular radio channel and SAT to
30 another cellular telephone call. In most cellular
radiotelephone systems, the predetermined length of time
for loss of SAT is typically greater than five seconds.
When battery 300 is removed during a cellular
telephone call in order to replace it with a fully-charged
3~ battery, timer 400 produces an output signal 414 having a
binary zero state (approximately signal ground) for a period
of approximately four seconds which is shorter than the
WO 91/02424 PCI`/US90/03387
3~ ~tj~ - 6 -
base site loss of SAT detection (at least five seconds). If
another battery 300 is plugged into portable telephone 100
within the four second period, cellular telephone 100 may
detect the binary zero state of timer output signal 414 and
re-enter the cellular telephone call that was in process
when the discharged battery 300 was removed. If the fully
charged battery 300 was not plugged in within the four
second period, timer output signal 414 will have a binary
one state (approximately 5 VDC) and the previous cellular
10 telephone call will not be re-entered. A cellular telephone
call is also re-entered after the momentary power source
interruption due to plugging and un-plugging vehicular
adaptor 200, and according to the present invention, the
operating mode of portable telephone 100 also
15 automatically changes.
Portable telephone 100 also includes a circuit 418,
420 and 422 which supplies standby current to RAM of radio
microcomputer 104. Capacitor 418 is kept charged through
resistor 420 and diode 422 to approximately +5V and
20 supplies RAM of radio microcomputer 104 with standby
current for at least four seconds when battery 300 or
external power source 119 is interrupted. Diode 422 also
prevents capacitor 418 from discharging into the +5V
supply when the +5V supply is off. Resistor 420 limits the
2~ charging surge current applied to capacitor 418.
Alternatively, back-up battery 424 may be used to supply
RAM of radio microcomputer 104 with standby current via
diode 427.
In order to re-establish a cellular telephone call after
30 a power source change, certain call parameters need to be
stored in RAM of radio microcomputer 104. Such call
parameters include, for example and without limitation, the
present cellular channel number (corresponding to the
transmitter and receiver frequencies of cellular
20370~
WO 91/02424 PCl/US90/03387
- 7 -
transceiver 102), the present supervisory audio tone (SAT)
frequency, the present transmitter power level setting (i.e.
one of eight possible levels), a call state active flag to
indicate that a call was in process prior to the power
5 source change, and the present user telephone number that
was used to place the call (the user may have a cellular
telephone with multiple telephone numbers). These call
parameters are stored in RAM of radio microcomputer 104.
Referring next to Figure 2, there is illustrated a flow
10 chart for the power-up process used by microcomputer 104
in Figure 1 for re-entering a cellular telephone call in
process before a power source change and determining the
new operating mode of portable telephone 100. Entering at
START block 202, the process proceeds to decision block
15 204, where a check of the call state active flag (binary one
= call in process) is made to determine if a call had been in
- process. If not, NO branch is taken to block 208 for
executing the normal power up sequence. If a call had been
in process, YES branch is taken from decision block 204 to
20 decision block 206, where a check is made to determine if
timer output signal 414 has a binary zero state. If not, NO
branch is taken to block 208 for executing the normal
power up sequence.
If timer output signal 414 has a binary zero state,
25 YES branch is taken from decision block 206 to decision
blocks 210, 212, 214 and 218 to determine the new
operating mode of portable telephone 100, which may be
different from the operating mode prior to the power
source change. Portable telephone 100 may be in one of
30 four operating modes, the bansry powered mode, the
battery eliminator mode, the duplex hands-free (DHFA)
mode, or the mobile transceiver (CVC) mode. At decision
block 210, a check is made to determine if portable
telephone 100 is in the battery powered mode.
WO 91/02424 PCI`/US90/03387
~,~3~ 8-
Microprocessor 104 detects the presence of an external
power source by monitoring the external power source
signal 1 19 through line conditioner 1 16. Line conditioner
116 may be implemented using a bipolar NPN-type
5 transistor having a resistor coupled from its collector to
the +5V supply, and a resistor coupled from its base to
signal ground, and a resistor coupled from its base to the
external power source signal 119. Line conditioner 116
converts the external power source signal 119 to a binary
10 signal 123 having a binary state indicating whether or not
the external power source 119 is present (i.e., binary zero
state s external power source 11g present).
When an vehicular adaptor 200 is plugged into
portable telephone 100, switch 128 is mechanically
15 engaged and disconnects battery 300 from portable
telephone 100. This may be accomplished by means of a
protrusion on the connector of vehicular adaptor 200.
When mechanically engaged, the protrusion on the
connector of vehicular adaptor 200 opens switch 128 which
20 in turn disconnects battery 300. When portable telephone
100 is not plugged into vehicular adaptor 200, switch 128
is normally closed. A diode 117 is connected between line
conditioner 116 and battery 300 to prevent battery 300
from enabling line conditioner 116 when external power
25 source 119 is not present.
If portable telephone 100 is in the battery powered
mode, YES branch is taken from decision block 210 to block
228, where the battery powered mode flag is set (i.e., set -
binary one state). If portable telephone 100 is not in the
30 battery powered mode, NO branch is taken from decision
block 210 to decision block 212, where a check is made to
determine if portable telephone 100 is in the battery
eliminator mode. If so, YES branch is taken to block 226,
where the battery eliminator mode flag is set. If portable
2037n~0
WO 91/02424 PCI'/US90/03387
telephone 100 is not in the battery eliminator mode, NO
branch is taken from decision block 212 to decision block
214, where a check is made to determine if portable
telephone 100 is in the DHFA mode. If so, YES branch is
5 taken to block 224, where the DHFA mode flag is set. If
portable telephone 100 is not in the DHFA mode, NO branch
is taken from decision block 214 to decision block 218,
where a check is made to determine if portable telephone
100 is in the CVC mode. If so, YES branch is taken to block
10 222, where the CVC mode flag is set. If portable telephone
100 is not in the CVC mode, NO branch is taken from
decision block 218 to block 220, where a restart is
i n iti ated .
From blocks 222, 224, 226 and 228, the process next
15 proceeds to block 230, where the audio paths for portable
telephone 100 are set up. If portable telephone 100 is in
- the battery powered mode or the battery eliminator (see
Figure 7) mode, audio amplifiers 122 and 126 are enabled
and the transmitter (TX) audio 121 and receiver (RX) audio
20 125 are routed to microphone 120 and speaker 124,
respectively. If portable telephone is in the DI~FA mode,
audio amplifiers 122 and 126 are disabled and the
transmitter (TX) audio 121 and receiver (RX) audio 125 are
routed to the the hands-free circuitry of vehicular adaptor
25 200 for processing and coupling to the hands-free
microphone 512 and speaker 510, respectively, as shown in
Figure 5. If portable telephone is in the CVC mode, audio
amplifiers 122 and 126 are disabled and the mobile
transceiver in vehicular adaptor 200 is used, as shown in
30 Figure 6.
Next, at block 232, the parameters of cellular
transceiver 102 are read out of non-volatile memory (RAM)
of microcomputer 104 and loaded into cellular transceiver
102. These parameters were previously stored into RAM of
WO 91/02424 PC~/US90/03387
microcomputer 104 for identifying the cellular radio
channel for the call that was in process. Such parameters
include, for example and without limitation, the data which
is loaded into the transmitter and receiver synthesizers for
tuning cellular transceiver 102 to the desired eellular radio
channel. Then, at bloek 234, the supervisory audio tone
(SAT) and the radio transmitter power level are read out of
RAM of mieroeomputer 104 and also loaded into eellular
transeeiver 102. Onee the eellular radio ehannel, SAT and
10 radio transmitter power level are loaded into eellular
transceiver 102, the eall that was in process before the
power source change ean be re-entered at bloek 236. Thus,
by using the flow ehart illustrated in Figure 2, it is
possible to not only re-enter a eall after a power souree
15 ehange but also automatically ehange between four
different modes of operation of portable telephone 100. In
other words, the user can switeh from battery operation to
operation with another battery, battery eliminator adaptor,
hands-free adaptor, or mobile transceiver adaptor
20 automatieally during a call as long as the user
aeeomplishes the power souree change within the
approximately four seeond time interval of timer 400.
Referring next to Figure 3, there is illustrated a flow
ehart for the proeess used by microeomputer 104 in Figure
25 1 for storing and updating specifie eellular information
during a cellular telephone call. Entering at START block
302 during a cellular telephone call, the process proeeeds
to block 304, where the cellular radio channel number, SAT,
present user telephone number, and radio transmitter power
30 level are stored in RAM of microeomputer 104, and the call
state aetive flag is set and likewise stored. Next, at
deeision bloek 306, a check is made to determine if a new
cellular radio channel has been assigned to portable
telephone 100. A new cellular radio channel is assigned to
20~050
- WO 91/02424 PCr/US90/03387
- 11 -
portable telephone 100 when it is handed off from one base
station radio to another. Handoff typically occurs when
portable telephone 100 moves from one cell into another. If
so, YES branch is taken to block 308, where the new
5 cellular radio channel number is stored in RAM of
microcomputer 104 . From block 308 and NO branch of
decision block 306, the process proceeds to decision block
310, where a check is made to determine if a new SAT has
been assigned to portable telephone 100. A new SAT may
10 also be assigned to portable telephone 100 when it is
handed off from one base station radio to another. If so,
YES branch is taken to block 312, where the new SAT is
stored in RAM of microcomputer 104 . From block 312 and
NO branch of decision block 310, the process proceeds to
15 decision block 314, where a check is made to determine if a
new radio transmitter power level has been assigned to
- portable telephone 100. A new radio transmitter power
level is assigned to portable telephone 100 when the base
station radio determines that the magnitude of the radio
20 frequency signal received from portable telephone 100 is
either lower than a minimum threshold or higher than a
maximum threshold and therefore needs to be adjusted.
There are currently eight different power levels for
cellular telephones, of which portable telephones use six,
2~ the two highest power levels not being used due to
limitations in the output power of portable telephones. If a
new power level has been assigned, YES branch is taken to
block 316, where the new power level is stored in RAM of
microcomputer 104. From block 316 and NO branch of
30 decision block 314, the process proceeds to decision block
318, where a check is made to determine if the call has
been terminated. If not, No branch is taken back to decision
block 306 to repeat the foregoing process. If the call has
been terminated, YES branch is taken from decision block
WO 91/OU24 PCI/US90/03387
3~Q 1 2 -
318 to block 320, where the call state flag is cleared (i.e.
cleared = binary zero), and thereafter a resean repeating
the foregoing process takes place at block 322. The flow
chart of Figure 3 is executed periodically in response to an
5 interrupt which sets the call state flag.
Figure 4 is a circuit diagram of timer 400 in cellular
portable telephone 100 in Figure 1. Timer 400 includes
capacitor 406 which is charged via diode 402 and resistor
404 when the TX PREKEY signal has a binary one state
10 (approximately 4.75 VDC). The TX PREKEY signal has a
binary one state whenever the radio transmitter of cellular
transceiver 102 is enabled, which is primarily during a
cellular telephone call. By only charging capacitor 406
when the TX PREKEY signal has a binary one state, current
15 drain from battery 300 is minimized. If capacitor 406 has
been charged to approximately 4.75 VDC during a cellular
telephone call and battery 300 is removed or otherwise
interrupted, transistor 408 will be turned on via resistors
410 and 412 providing a binary zero state at its output, the
20 timer output signal 414. The binary zero state of timer
output signal 414 will be maintained for approximately
four seconds based primarily upon the-values selected for
capacitor 406, resistors 410 and 412 and the beta of
transistor 408. If another battery 300 is plugged in or
25 vehicular adaptor 200 is plugged in within the four second
period, the binary zero state of the timer output signal 414
may be detected by microcomputer 104 and the cellular
telephone call in process before the power source change
may be re-entered. If more than four seconds have elapsed,
30 the timer output signal 414 will have a binary one state
since capacitor 406 will be discharged to approximately
signal ground turning transistor 408 off and producing a
binary one state of the timer output signal 414 via resistor
416 to 15 VDC. When timer output signal 414 has a binary
2037050
WO 91/02424 PCI/US90/03387
- 13 -
one state after a power source change, the previous cellular
telephone call will not be re-entered.
Referring to Figure 5, there is illustrated a block
diagram of a hands-free adaptor embodiment of vehicular
adaptor 200 in Figure 1. Portable cellular telephone 100
receives its power via external power source connection
119 which is the output of conventional voltage regulator
502. The voltage supplied by vehicle battery 500 voltage is
regulated and controlled by voltage regulator 502. Control
circuitry 504 turns regulator output 119 on and off in
response to signals from vehicle ignition 506 and data bus
115. Data bus 11~ is used by portable telephone 100 to
sense if a hands-free adaptor 200 is plugged into portable
telephone 100. Receiver audio signal 125 from portable
telephone 100 is coupled to amplifier 508 in hands-free
adaptor 200 to boost the level to drive speaker 510. The
output from microphone 512 is connected to portable
cellular phone 100 via TX audio connection 121 of portable
telephone 100.
Referring to Figure 6, there is illustrated a block
diagram of a mobile transceiver adaptor embodiment of
vehicular adaptor 200 in Figure 1. Portable telephone.100
receives its power via external power source signal 119
which is the output of conventional voltage regulator 602.
The voltage supplied by vehicle battery 500 is regulated
and controlled by voltage regulator 602. Control circuitry
604 turns regulator output 119 on and off in response to
signals from vehicle ignition 606 and data bus 115. Data
bus 115 is used by portable telephone 100 to sense if a
mobile transceiver adaptor 200 is plugged into portable
telephone 100. In this mode of operation the transceiver
circuitry 614 in the mobile transceiver are used instead of
cellular transceiver 102 in portable telephone 100, which
is turned off. This configuration allows for improved
WO 91/02424 PCr/US90/0338-.
- 14 -
'1,~3''Q i
system performance (i.e. higher TX power and better RX
sensitivity). Transmit and receive audio for the mobile
transceiver 614 can be coupled to either the TX audio signal
121 and RX audio signal 125 of portable telephone 100 or
5 the hands-free microphone 612 and speaker 610 under
control of control circuitry 604 and data bus 115.
Mobile transceiver adaptor 200 may be a conventional
cellular transceiver, and in the preferred embodiment is the
transceiver of the cellular telephone available from
10 Motorola, Inc., and described in Motorola user's manual no.
68P81116E58-B, entitled ~DYNATAC 6000XL Cellular Mobile
Telephone User's Manual", published by and available from
Motorola C 8 E Parts, 1313 East Algonquin Road,
Schaumburg, Illinois 60196.
Referring to Figure 7, there is illustrated a block
diagram of a battery eliminator adaptor embodiment of
vehicular adaptor 200 in Figure 1. Portable telephone 100
receives its power via external power source connection
119 which is the output of conventional voltage regulator
20 702. The voltage supplied by vehicle battery 500 is
regulated- by voltage regulator 702.
In summary, a unique portable radiotelephone, has
been described which automatically accommodates a power
source change between the portable's battery and another
25 battery or a vehicular adaptor coupled to an external
battery during a cellular telephone call. In addition, the
portable radiotelephone of the present invention also
automatically changes between four different modes of
operation in response to a power source change during a
30 cellular telephone call.
