JP2000206276A - Mobile radio communication terminal incorporating electronic wave clock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct time and to provide accurate time by incorporating a receiver with a long-wave standard electronic wave in a mobile radio communication terminal and achieving the function of an electronic wave clock. SOLUTION: A long-wave standard electronic wave is received by an antenna 1 for long wave and a reception low-noise amplifier(LNA) 2 for long wave, and a reference marker in a standard signal being received by a reception pulse extraction circuit 3 is detected and is sent to a time generation circuit 4 and a time difference measurement circuit 5 as a pulse signal. On the other hand, a clock 7 being generated from an oscillator 12 by an incorporated crystal oscillator is counted by a built-in clock and is sent to the measurement circuit 5 via a time signal generation circuit 6 for measurement. The difference between time from the standard electronic wave being received and time from the built-in clock is measured and is sent to a correction signal generation circuit 7, and a correction signal corresponding to the time difference is sent to the built-in clock, thus correcting time. Accurate time is displayed on a display 11 as an electronic wave clock also at the mobile radio communication terminal by the loop control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication terminal, for example, a mobile phone, a PHS, and the like, to which a function of a radio clock using a long-wave standard radio wave is applied.

[0002]

2. Description of the Related Art In Japan, a long-wave standard radio wave JG2AS including a time code is transmitted as a radio clock.
A method of measuring the time by receiving the standard radio wave and a method of using time information multiplexed in teletext broadcasting as described in JP-A-09-292478 can be used. 2 and 4 are circuit block diagrams of these conventional examples.

[0003] These are intended only to provide a user with accurate time as a radio clock.

A mobile communication terminal has a built-in crystal oscillator and a voltage controlled crystal oscillator, and provides a clock function.
FIG. 3 shows this block diagram.

[0005]

Since the accuracy of time is determined by the accuracy of the built-in crystal oscillator, a mobile communication terminal may have a high-precision crystal oscillator in order to increase the time accuracy. Although it is necessary, due to the nature of mobile communication terminals,
The mobile communication terminal itself may be located in a place where the temperature is high or low, such as in a car, and the guaranteed temperature range of the mobile communication terminal itself is wide.

For this reason, in an actual use mode, a time lag occurs due to a shift in the oscillation frequency of the crystal oscillator due to temperature or the like, and the accuracy of the transmission frequency of the mobile communication terminal also increases. In some cases, this may be affected by the displacement of the crystal oscillator in the voltage-controlled crystal oscillator built in the device.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a receiver for a long-wave standard radio wave in a mobile communication terminal in order to improve the time accuracy of the mobile communication terminal. By incorporating it and having the function of a radio clock, the time can be corrected and the accurate time can be provided to the user.

When the mobile communication terminal is normally receiving a radio wave from a communication base station during a call or a call, the transmission frequency of the mobile communication terminal follows the radio wave from the base station. Therefore, if you can maintain the accuracy of the transmission frequency, but can not receive the radio waves from the base station normally,
Since only the accuracy of the crystal oscillator built in the mobile communication terminal is used, the oscillation frequency of the voltage controlled crystal oscillator is corrected based on the built-in radio clock.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

A conventional mobile communication terminal is, as shown in FIG.
The oscillation frequency of the quartz oscillator connected to the control (microcomputer) unit of No. 10 has been multiplied and counted, and the time is displayed on a clock.

On the other hand, the part corresponding to claim 1 of the present invention is that the mobile communication terminal in FIG. 1 has a built-in part for receiving a long-wave standard radio wave. 1 and a long wave reception LNA (low noise amplifier) 2 to receive a long wave standard radio wave, and a reception pulse extraction circuit 3 detects a reference marker in the received long wave standard signal, and outputs a time signal of 4 as a pulse signal. It is sent to the generation circuit and the time difference measurement circuit 5.

On the other hand, the clock generated from the oscillator 12 by the built-in crystal oscillator is timed by the built-in clock 8 and sent to the time difference measuring circuit 5 through the measuring time signal generating circuit 6. . The time difference measurement circuit 5 measures the difference between the time from the received long-wave standard time signal and the time from the built-in clock, sends the measured time difference to the correction signal generation circuit 7, and the correction signal generation circuit 7 Sends a correction signal corresponding to the time difference to a built-in clock to correct the time. With this loop control, the mobile communication terminal also displays the accurate time on the display 11 as a radio clock.

According to a second aspect of the present invention, a mobile communication terminal such as a mobile phone receives a radio wave from a base station of the mobile phone with an antenna of 22 and receives a signal from an antenna receiving device via an antenna switching device. Down-converts the frequency at
The signal is sent to the demodulation unit 17. The received signal is further subjected to frequency division / multiplication processing, and compared with the divided frequency of the frequency output from the voltage-controlled crystal oscillator 13 so that the control voltage is supplied from the microcomputer 10 to the voltage 13 Sent to control crystal oscillator.

Here, when the mobile communication terminal is out of the service area of the base station and cannot receive radio waves from the base station with the 22 antennas, the reception and the determination of the oscillation frequency are determined by the 16 and 20 oscillators and This depends on the accuracy of the voltage controlled crystal oscillator 13 of the mobile communication terminal. Here, if the mobile communication terminal undergoes a sudden change in environment such as temperature, the oscillation frequency of the voltage controlled crystal oscillator 13 will be shifted. When returning to the service area of the base station again, it takes some time until the voltage controlled crystal oscillator 13 is corrected by the radio wave of the base station.

Therefore, when the mobile communication terminal is out of the service area of the base station and cannot receive radio waves from the base station with the 22 antennas, the above-described built-in radio clock section is used to transmit the radio signal from the radio clock section. An accurate clock is sent to the microcomputer 10, and the microcomputer 10 compares the oscillation frequency from the voltage-controlled crystal oscillator 13 with a divided signal, and adjusts the control voltage so that the difference disappears. It is possible to maintain a proper oscillation frequency and immediately follow the base station when returning to the service area of the base station.

[0016]

According to the present invention, a user of a mobile communication terminal can
In addition to being able to get accurate time as a radio clock,
The problem of a call or a standby due to a sudden temperature change or the like can be eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a mobile communication terminal incorporating a conventional radio clock.

FIG. 2 is a block diagram showing a conventional radio clock using a long-wave standard radio wave.

FIG. 3 is a block diagram showing a mobile communication terminal according to the present invention.

FIG. 4 is a block diagram of a radio-controlled timepiece by teletext broadcasting according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Long wave standard radio wave reception antenna, 2 ... Reception LNA (low noise amplifier), 3 ... Reception pulse extraction circuit, 4 ... Time signal generation circuit, 5 ... Time difference measurement circuit, 6 ... Measurement time signal generation circuit, 7 ... Correction Signal generation circuit, 8 ... built-in clock, 10
.. Microcomputer, 11 display device, 12 crystal oscillator transmission circuit, 13 voltage-controlled crystal oscillator, 14 PLL circuit, 1
5: transmitting device, 16: oscillator, 17: modulator and demodulator,
18 antenna switcher, 19 mixer, 20 oscillator, 21 receiving device, 22 mobile communication terminal antenna, 1
21: text multiplex broadcasting antenna, 122: text multiplex broadcasting receiving device, 123 ... FM demodulation unit, 124 ... MSK demodulation unit, 125 ... decoding unit, 126 ... sync signal reproduction unit, 127
... frame memory section, 128 ... error correction section, 129 ...
Modified signal generator 130, Protocol decoder 131
Time information holding unit, 132 ... received data memory, 133 ...
Control unit, 134: display control unit, 135: input unit, 136
... Display unit, 137 ... Time correction unit, 138 ... Timekeeping unit, 13
9: frequency divider, 140: oscillator.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsuro Soma 1410 Inada, Hitachinaka-shi, Ibaraki Pref.Hitachi, Ltd.Video Information Media Division (72) Inventor Hideaki Watanabe 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Japan Stock Company F term in Hitachi Image Information System Co., Ltd. (reference) 2F002 AA12 CB02 CB04 ED02 FA16 GA06

Claims (2)

[Claims] 1. A built-in device for receiving a long-wave standard radio wave,
A mobile communication terminal with a built-in radio clock that has a function of extracting time information from the received long-wave standard time signal and correcting the clock of the mobile communication terminal itself. 2. The mobile communication terminal according to claim 1, wherein the mobile communication terminal has a function of correcting the oscillation frequency of a voltage-controlled crystal oscillator built in the mobile communication terminal based on the corrected time data. Mobile communication terminal with built-in radio clock.