Dual-mode radio communication device having function for selectively using analog or digital mode

The present invention relates to a remaining battery display function of a dual-mode radio communication device selectively using an analog mode and a digital mode as a communication mode between the device and a base station, such as a car telephone and a portable telephone.

As is well-known, in a conventional dual-mode radio communication device, consumed current of a battery varies between an analog mode and a digital mode and so does a discharge (consumption) characteristic between them.

Even though a remaining amount of power of a battery (hereinafter referred to as a remaining battery) is displayed or an alarm for a decrease in voltage is raised (a DISCHARGE lamp lights up) on the basis of a preset threshold voltage, callable time will vary from mode to mode. For this reason, the conventional dual-mode radio communication device has a problem that a user cannot make use of the callable time effectively based on the display of a remaining battery or the alarm for a decrease in voltage.

The object of the present invention is to provide a dual-mode radio communication device capable of correctly alerting a user to a remaining battery corresponding to a communication mode.

In order to attain the above object, a dual-mode radio communication device according to the present invention has data of a battery consumption characteristic in an analog mode and that in a digital mode. The device determines a remaining battery based on data corresponding to a selected one of the analog and digital modes and alerts it to a user.

Consequently, according to the dual-mode radio communication device having the above constitution, the remaining battery corresponding to a communication mode can correctly be alerted to the user and accordingly the user can utilize his or her callable time with high efficiency.

FIG. 1 is a circuit block diagram illustrating the constitution of a dual-mode radio communication device according to one embodiment of the present invention;

FIG. 2 is a graph showing battery discharge characteristics in an incoming-call standby status in each communication mode;

FIG. 3A is a table for explaining a threshold voltage level for displaying a remaining battery in a communication mode stored in a storage section; and

FIG. 3B is a table for explaining a threshold voltage level for displaying a remaining battery in another communication mode stored in the storage section.

Hereinafter an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 illustrates the constitution of a dual-mode radio communication device according to the embodiment of the present invention. The dual-mode radio communication device illustrated in FIG. 1 includes two communication modes of an analog mode and a digital mode of a CDMA (code division multiple access) system.

When the dual-mode radio communication device is set in the digital mode, switching circuits 9 and 14 are each switched to a PCM code processing section 8 in response to a switching control signal SWC output from a control section 20 .

In this state, a radio frequency signal, which is transmitted from a base station (not shown) through a digital channel, is received by an antenna 1 and then input to a reception circuit (RX) 3 via a duplexer (DUP) 2 .

The radio frequency signal received by the reception circuit 3 is mixed with a received local oscillation signal output from a frequency synthesizer (SYN) 4 into an intermediate frequency signal whose frequency is varied. The frequency of the received local oscillation signal generated from the frequency synthesizer 4 is indicated by a control signal SYC output from the control section 20 .

The received intermediate frequency signal is quadrature-demodulated in a CDMA signal processing section 6 and then spread inversely to extract reception data for the device. The extracted reception data is expanded in a voice code processing section 7 and converted to a digital reception signal.

The digital reception signal is decoded into an analog reception signal in the PCM code processing section 8 . The analog reception signal is amplified by an amplifier 10 through the switching circuit 9 and then output from a speaker 11 loudly.

On the other hand, a transmission signal of a speaker input to a microphone 12 is amplified by an amplifier 13 and then supplied to the PCM code processing section 8 through the switching circuit 14 .

The analog reception signal input to the PCM code processing section 8 is processed by PCM and converted into a digital transmission signal. After that, it is compressed by the voice code processing section 7 and input to the CDMA signal processing section 6 as transmission data.

The transmission data input to the CDMA signal processing section 6 is spread using a PN code corresponding to a transmission channel, then quadrature-demodulated and supplied to a transmission circuit (TX) 5 .

In the transmission circuit 5 , the quadrature-demodulated signal is synthesized with a transmitted local oscillation signal into a radio frequency signal, and this signal is high-frequency-amplified. The transmitted local oscillation signal is output from the frequency synthesizer 4 in response to an instruction of the control section 20 .

The transmission radio frequency signal output from the transmission circuit 5 is supplied to the antenna 1 via the duplexer 2 and transmitted therefrom toward the base station (not shown).

Next, when the device is set in the analog mode, the switching circuits 9 and 14 are each switched to an analog voice circuit 15 in response to the switching control signal SWC output from the control section 20 .

In this state, the radio frequency signal transmitted from the base station (not shown) through an analog channel, is received by the antenna 1 and then input to the reception circuit 3 via the duplexer 2 . In this reception circuit 3 , the radio frequency signal is frequency-converted to an intermediate frequency signal. The received intermediate frequency signal output from the reception circuit 3 is input to the analog voice circuit 15 .

In the analog voice circuit 15 , the received intermediate frequency signal is reproduced as an analog reception signal by FM demodulation. This analog reception signal is amplified by the amplifier 10 through the switching circuit 9 and then output from the speaker 11 loudly.

In contrast, the speaker's transmission signal output from the microphone 12 is amplified by the amplifier 13 and then input to the analog voice circuit 15 via the switching circuit 14 . A modulated signal, which is FM-modulated in response to the transmission signal, is generated from the analog voice circuit 15 , and supplied to the transmission circuit 5 .

In the transmission circuit 5 , the modulated signal is mixed with the transmitted local oscillation signal generated from the frequency synthesizer 4 and corresponding to the radio frequency of the analog channel and up-converted to a radio frequency signal. This signal is then high-frequency-amplified to a predetermined output level.

The radio frequency signal output from the transmission circuit 5 is supplied to the antenna 1 through the duplexer 2 and transmitted toward the base station (not shown) from the antenna 1 .

The control section 20 includes a microcomputer as a main control section to exercise control over the respective sections for radio connection control and call control. The control section also includes a remaining battery determination means 20 a and a remaining battery display control means 20 b as new control functions.

The remaining battery determination means 20 a is designed to determine a remaining battery level based on both detection results of a voltage detection circuit 32 , which will be described later, and data stored in an analog-mode discharge characteristic storage area 21 a or a digital-mode discharge characteristic storage area 21 b.

The remaining battery display control means 20 b is designed to control display of a remaining battery in an LCD display device of a control unit 22 in response to a determination result of the remaining battery determination means 20 a.

The storage section 21 includes a semiconductor memory such as a ROM and a RAM as a storage medium. The storage medium has an area for storing various types of control data, various types of set data and dial data corresponding to abbreviated dialing as well as control programs of the control section 20 and ID data of the device itself necessary for authentication. The storage medium also has the analog and digital-mode discharge characteristic storage areas 21 a and 21 b.

The analog-mode discharge characteristic storage area 21 a is used to store threshold data of display of a remaining battery set on the basis of battery discharge (consumption) characteristics in an incoming-call standby status in the analog mode as shown in FIG. 2 . One example thereof is shown in FIG. 3 A.

The digital-mode discharge characteristic storage area 21 b is used to store threshold data of display of a remaining battery set on the basis of battery discharge (consumption) characteristics in an incoming-call standby status in the digital mode as shown in FIG. 2 . One example thereof is shown in FIG. 3 B.

The control unit (CU) 22 is provided with a key group such as a dial key, a call key, a termination key, a volume control key and a mode designation key, an LCD display for displaying a telephone number of the party on the other end line, an operation status of the device and the like, and an LED lamp indicative of a discharge status of a battery 30 (which requires charge of a battery 30 ).

In FIG. 1, reference numeral 31 indicates a power supply circuit. The power supply circuit 31 generates an operating power supply voltage Vcc based on an output of the battery 30 and supplies it to each of the circuits.

The voltage detection circuit (ADC) 32 detects a voltage value of the battery 30 which varies with a consumed current and notifies the control section 20 of the detection result (digital data).

An alert operation of a remaining battery of the dual-mode radio communication device having the above constitution will now be described.

First, the remaining battery determination means 20 a determines a battery remaining level on the basis of a voltage value of the battery 30 notified by the voltage detection circuit 32 .

When the device is set in the analog mode, the voltage value of the battery 30 is compared with threshold data stored in the analog-mode discharge characteristic storage area 21 a to determine the above remaining battery level. When the device is set in the digital mode, the voltage value is compared with threshold data stored in the digital-mode discharge characteristic storage area 21 b to determine the above remaining battery level.

Next, the remaining battery display control means 20 b causes a remaining battery to be displayed on the LCD display device of the control unit 22 , as shown in FIGS. 3A and 3B, in response to a determination result of the remaining battery determination means 20 a.

If the threshold voltage is 4.3V or lower in the analog mode and that is 4.5V or lower in the digital mode, the LED lamp of the control unit 22 lights up to notify a user that the battery will be exhausted soon. After that, both the level determination of the remaining battery determination means 20 a and the display control of the remaining battery display control means 20 b are repeated to notify the user of the remaining amount of battery 30 .

As described above, the dual-mode radio communication device having the above constitution includes level determination data used when the analog mode is selected and level determination data used when the digital mode is selected. The remaining amount of battery 30 is determined on the basis of data of these level determination data which corresponds to a communication mode.

According to the foregoing dual-mode radio communication device, therefore, a user can correctly know the remaining battery corresponding to the communication mode and thus use callable time with efficiency.

Needless to say, various changes and modifications can be made without departing from the scope of the subject matter of the present invention.