JP2006261998A - Mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the receiving sensitivity of a second radio signal high while reducing interference caused by the transmission of a mobile communication radio signal. <P>SOLUTION: A filter circuit 63 is arranged between an antenna 5 and a tuner 61 in a broadcasting receiving unit 6. The filter circuit 63 is composed of a filter 631, a bypass circuit 634, changeover switches 632, 633 for switching these filter 631 and bypass circuit 634. Then, by switching operations of the changeover switches 632, 633, the filter circuit 631 is connected between the broadcasting receiving antenna 5 and the tuner 61 during the transmission of the mobile communication radio signal, whereas the bypass circuit 634 is connected between the broadcasting antenna 5 and the tuner 61 during the nontransmission of the mobile communication radio signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mobile communication terminal equipped with, for example, a terrestrial digital broadcast receiver.

  In recent years, in mobile communication terminals such as mobile phones and PDAs (Personal Digital Assistants), for example, terminals equipped with broadcast receivers for receiving radio broadcasts, terrestrial television broadcasts, mobile digital satellite broadcasts, An increasing number of terminals are equipped with a short-range wireless communication standard wireless communication device for performing wireless data communication with peripheral devices (see, for example, Patent Document 1).

By providing such a broadcast receiver or wireless communication device, the user can watch a television broadcast in addition to the original mobile communication, or use a personal computer or various other devices by simply having one mobile communication terminal. Data communication can be performed with peripheral devices such as service terminals, which is very convenient.
JP 2003-273978 A

  However, in this type of terminal, when a radio signal is transmitted from a transceiver for mobile communication, for example, for location registration or handover during a broadcast reception period or a period in which radio communication is performed with a peripheral device. In some cases, the radio signal for mobile communication becomes an interference wave, which deteriorates the reception sensitivity of the broadcast signal or the radio data communication signal in the broadcast receiver or the radio communication device.

  Therefore, a filter is disposed in front of the broadcast receiver or the wireless communication device, and the filter suppresses the interference signal corresponding to the mobile communication wireless signal while allowing the broadcast signal or the wireless data communication signal to pass therethrough. Has been proposed. However, since the filter usually has an insertion loss of about 2 to 3 dB, the insertion sensitivity of the broadcast signal or the wireless data communication signal deteriorates due to the insertion of this filter. This causes the problem that the communicable area between the two becomes narrower.

  The present invention has been made paying attention to the above circumstances, and its object is to maintain high reception sensitivity of the second radio signal while reducing interference caused by the first radio signal for mobile communication. It is to provide a mobile communication terminal that enables the above.

  In order to achieve the above object, a first invention provides a first radio circuit for transmitting a first radio signal for mobile communication, and a second radio signal having a frequency band different from that of the first radio signal. And a second wireless circuit that receives the first wireless circuit, wherein band suppression means is arranged on an input side of the second wireless circuit, and the first wireless circuit is connected to the first wireless circuit by the band suppression means. The frequency band of the first radio signal included in the second radio signal is suppressed only during the period in which the radio signal is transmitted.

  Therefore, according to the first aspect, the first radio signal included in the second radio signal is suppressed by the band suppression unit only during the period in which the first radio signal is transmitted from the first radio circuit. For this reason, the interference by the radio signal for mobile communication with respect to the second radio signal is reduced. On the other hand, since the band suppression processing by the band suppression unit is not performed during the period when the first radio signal is not transmitted, the period during which the reception sensitivity of the second radio signal deteriorates is greatly shortened. That is, it is possible to maintain high reception sensitivity of the second radio signal while reducing interference caused by the radio signal for mobile communication.

  On the other hand, to achieve the above object, the second invention provides a first radio circuit for transmitting a first radio signal for mobile communication, and a second radio circuit having a frequency band different from that of the first radio signal. In a mobile communication terminal comprising a second radio circuit for receiving a radio signal, a means for detecting a transmission power level of the first radio signal transmitted from the first radio circuit is provided, and the second radio circuit is provided. Band suppression means is arranged on the input side of the radio circuit. Then, only when the detected transmission power level of the first radio signal exceeds a preset threshold value, the band suppression unit performs the first radio included in the second radio signal only. In this configuration, the frequency band of the signal is suppressed.

  Therefore, according to the second invention, when the first radio signal whose transmission power level exceeds the threshold value, that is, the first radio signal that exceeds the permissible interference level is transmitted, the second radio signal is included in the second radio signal. Since the frequency band of one radio signal is suppressed, the interference by the first radio signal with respect to the second radio signal is reduced. On the other hand, when the transmission power level of the first radio signal does not exceed the threshold value, that is, when the interference allowable level is not exceeded, the band suppression process for the second radio signal is not performed.

  That is, not only during the period when the first radio signal is not transmitted, but also when the transmission power level is a level that does not interfere with reception of the second radio signal even during the period when the first radio signal is transmitted. Band suppression processing is not performed. For this reason, the period during which the reception sensitivity of the second radio signal deteriorates is further shortened, and thereby, the reception sensitivity of the second radio signal can be maintained even higher while reducing the interference caused by the radio signal for mobile communication. It becomes possible.

  In the first and second inventions, the band suppression means includes a filter circuit having a frequency pass characteristic that suppresses the frequency band of the first radio signal, a bypass circuit that bypasses the filter circuit, and a switching circuit. Consists of. Then, the filter circuit and the bypass circuit are switched between the filter circuit and the bypass circuit by the switching circuit, so that the filter circuit and the bypass circuit are alternatively inserted between the antenna and the second radio circuit. If comprised in this way, it can be implement | achieved only by the simple circuit structure and switching control of only switching of a filter circuit and a detour circuit.

  At this time, when the second radio signal has an effective symbol period and a guard interval, for example, as in a terrestrial digital broadcast signal, the switching process by the switching circuit is performed within the guard interval period. Good. If comprised in this way, the malfunction which causes a 2nd wireless signal to lose | synchronize etc. by the said switching process can be prevented.

Further, in the second invention, when the transmission power level of the detected first radio signal exceeds a preset first threshold value in the band suppression means, the second radio signal is thereafter banded. The transmission power level of the first radio signal input to the second radio circuit via the suppression means and detected in this state is lower than the second threshold value set smaller than the first threshold value. In this case, the second radio signal is then input to the second radio circuit bypassing the band suppressing means.
With this configuration, it is possible to give a hysteresis characteristic to the switching process of whether the second wireless signal is passed through the band suppression unit or to be detoured, and when the ripple component remains in the switching control signal, When the transmission power level of the first radio signal fluctuates in the vicinity of the threshold value, it is possible to realize a highly stable switching process by preventing the band suppressing means from frequently performing the switching process.

  In short, according to the present invention, the band suppression unit performs the second suppression only during the period when the first radio signal for mobile communication is transmitted, or only during the period when the transmission power level of the first radio signal exceeds the threshold value. The frequency band of the first radio signal included in the radio signal is suppressed. Therefore, it is possible to provide a mobile communication terminal capable of maintaining high reception sensitivity of the second radio signal while reducing interference caused by the first radio signal for mobile communication.

  Hereinafter, an embodiment of a mobile communication terminal according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a first embodiment of a mobile communication terminal according to the present invention.
A radio signal transmitted from a mobile communication base station (not shown) is received by the mobile communication antenna 1 and then input to the mobile communication radio unit 2. The mobile communication radio unit 2 performs low-noise amplification, frequency conversion to an intermediate frequency or baseband frequency, and demodulation processing, thereby reproducing a received baseband signal, thereby generating a mobile communication signal processing unit 3. Is input. In the mobile communication signal processing unit 3, the input received baseband signal is decoded, and the received data reproduced by the decoding process is presented to the user via the input / output interface unit 4. For example, if the received data is voice data, the received voice is loudly output from the speaker 11, and if it is image data, an image is displayed on the display 14. When the received data is mail data or data downloaded from a website or the like, the data is stored in the storage unit 9 from the control unit 8.

  On the other hand, the user's transmitted voice data input to the microphone 12 and the image data captured by the camera 13 are input to the input / output interface unit 4 and then input to the mobile communication signal processing unit 3. Data such as e-mail created by operating the input device 17 is input from the control unit 8 to the mobile communication signal processing unit 3. In the mobile communication signal processing unit 3, the input transmission data is subjected to encoding processing, whereby a transmission baseband signal is generated and input to the mobile communication radio unit 2. The mobile communication radio unit 2 performs modulation, frequency conversion to a radio frequency, and power amplification on the input transmission baseband signal. The radio signal generated in the mobile communication radio unit 2 is transmitted from the mobile communication antenna 1 to the base station.

  On the other hand, the terrestrial digital broadcast signal transmitted from the broadcast transmission facility is received by the broadcast receiving antenna 5 and then input to the broadcast receiving unit 6, where the reception channel is selected and further demodulated, and then broadcast signal processing is performed. Input to unit 7. The broadcast signal processing unit 7 performs a decoding process on the input demodulated signal, thereby reproducing television image data, audio data, and character data. Among these, television image data and character data are displayed on the display 14 via the input / output interface unit 4, and audio data is output from the speaker 11 via the input / output interface unit 4.

The control unit 8 is composed of, for example, a microcomputer, and controls the operation of each unit of the mobile communication system and each unit of the broadcast reception system according to the operation mode designated and input by the user via the input device 17. The storage unit 9 uses, for example, an EEPROM or a hard disk as a storage medium, and stores application programs to be executed by the control unit 8, transmission / reception data such as mail, and control data such as a telephone directory.
Reference numeral 15 denotes a power supply circuit. The power supply circuit 15 generates an operating voltage Vcc based on the output voltage of the battery 16, and supplies the generated operating voltage Vcc to each unit.

  By the way, the broadcast receiving unit 6 and the mobile communication radio unit 2 are configured as follows. FIG. 2 is a circuit block diagram showing the configuration. That is, the broadcast receiving unit 6 performs a tuner 61 that performs channel selection processing on the received terrestrial digital broadcast signal, and OFDM (Orthogonal Frequency Division Multiplex) that demodulates the broadcast signal of the channel selected by the tuner 61. And a demodulator 62, and a filter circuit 63 is arranged on the input side of the OFDM demodulator 62.

  The filter circuit unit 63 includes a filter 631, a pair of changeover switches 632 and 633 disposed at both ends of the filter 631, and a bypass circuit 634 that bypasses the filter 631. The filter 631 has a band-pass characteristic that passes the terrestrial digital broadcasting band and suppresses the mobile communication transmission band. FIG. 7 shows an example of the band pass characteristic.

  On the other hand, the mobile communication wireless unit 2 includes a modulation unit 21, a frequency conversion unit 22, a transmission power amplifier (PA) 23, and an antenna duplexer (hereinafter referred to as DUP) 24. The transmission power amplifier 23 is supplied with the operating voltage Vcc output from the power supply circuit 15 via the power supply control switch 25. The power supply control switch 25 is turned on during the transmission period of the mobile communication radio signal according to the transmission control signal SW1 output from the control unit 8, and is turned off during other periods.

  The transmission control signal SW1 is supplied to the changeover switches 632 and 633 as a filter enable signal ES. The change-over switches 632 and 633 are switched in accordance with the enable signal ES. The change-over switches 632 and 633 are switched to the filter 631 side during the transmission period of the radio signal for mobile communication, and the filter 631 is connected between the broadcast receiving antenna 5 and the tuner unit 61. Connect to. On the other hand, during other periods, the circuit is switched to the bypass circuit 634 side, and the bypass circuit 634 is connected between the broadcast receiving antenna 5 and the tuner unit 61.

  Because of such a configuration, during reception of a terrestrial digital broadcast signal, for example, a location registration procedure for registering the location of the mobile communication terminal in the base station is executed, or the synchronization establishment destination base station is It is assumed that a handover procedure for switching is executed. When these procedures are executed, a radio signal is transmitted from the mobile communication terminal to the mobile communication base station, and the radio signal for mobile communication is received by the broadcast receiving antenna 5 together with the broadcast signal.

  However, during the transmission period of the radio signal for mobile communication, the “H” level transmission control signal SW1 output from the control unit 8 is supplied to the change-over switches 632 and 633 as the filter enable signal ES. The switches 632 and 633 are switched to the filter 631 side. Therefore, the filter 631 is inserted between the broadcast receiving antenna 5 and the tuner unit 61. For this reason, the radio signal for mobile communication received by the broadcast receiving antenna 5 together with the broadcast signal is suppressed to a signal level allowed as an interference wave by the filter 631. Therefore, the tuner unit 61 can perform accurate channel selection of the broadcast signal without being affected by the interference by the mobile communication radio signal.

  On the other hand, when the transmission period of the radio signal for mobile communication ends, the transmission control signal SW1 changes to the “L” level, whereby the power supply control switch 25 is opened and the power supply to the transmission power amplifier 23 is interrupted. Be drunk. At the same time, the transmission control signal SW1 is supplied as a filter enable signal ES to the changeover switches 632 and 633, and as a result, the changeover switches 632 and 633 are switched to the bypass circuit 634 side. For this reason, the broadcast receiving antenna 5 and the tuner unit 61 are directly connected by the detour circuit 634. Therefore, the terrestrial digital broadcast signal received by the broadcast receiving antenna 5 is input to the tuner unit 61 without being affected by the insertion loss of the filter 631 during the non-transmission period of the radio signal for mobile communication. For this reason, the tuner unit 61 can maintain high reception sensitivity with respect to the terrestrial digital broadcast signal.

  As described above, in the first embodiment, the filter circuit 63 is arranged between the antenna 5 and the tuner unit 61 in the broadcast receiving unit 6. The filter circuit 63 includes a filter 631, a bypass circuit 634, and selector switches 632 and 633 that switch between the filter 631 and the bypass circuit 634, and the filter 631 is broadcasted during a transmission period of a radio signal for mobile communication. The detour circuit 634 is connected between the broadcast receiving antenna 5 and the tuner unit 61 during the non-transmission period of the mobile communication radio signal.

  Therefore, in the transmission period of the radio signal for mobile communication, the radio signal for mobile communication received by the broadcast receiving antenna 5 is suppressed by the filter 631 to the signal level allowed as an interference wave, and then the tuner unit 61. As a result, the tuner unit 61 can select an accurate channel without being affected by the interference caused by the radio signal for mobile communication. On the other hand, in the non-transmission period of the radio signal for mobile communication, the filter 631 is bypassed by the bypass circuit 634, whereby the terrestrial digital broadcast signal is input to the tuner unit 61 without being affected by the insertion loss of the filter 631. Is done. For this reason, the tuner unit 61 can maintain high reception sensitivity with respect to the terrestrial digital broadcast signal.

  Further, in the first embodiment, the changeover switches 632 and 633 are controlled to switch using the existing transmission control signal SW1 generated from the control unit 8 for power supply control of the transmission power amplifier 23 as it is. For this reason, there is no need to newly generate a switching control signal, and a signal generation circuit therefor can be made unnecessary. Therefore, there is an advantage that can be realized with a simple circuit configuration.

(Second Embodiment)
The second embodiment of the present invention includes a function for detecting and determining the transmission power level of the transmission power amplifier, and a filter circuit that operates according to the determination result of this function. Then, the filter is connected between the broadcast receiving antenna and the tuner unit during the period when the transmission power level exceeds the reference level, while the bypass circuit is broadcast during the period when the transmission power level does not exceed the reference level. A connection is made between the receiving antenna and the tuner unit.

FIG. 3 is a block diagram showing a configuration of a filter control circuit unit which is a main part of the mobile communication terminal according to the second embodiment of the present invention. In the figure, the same parts as those in FIG.
A directional coupler 31 is inserted on the output side of the transmission power amplifier 23. The directional coupler 31 branches a part of the mobile communication radio signal output from the transmission power amplifier 23 and inputs it to the transmission power detection circuit 32. The transmission power detection circuit 32 outputs a DC voltage signal proportional to the transmission power level of the radio signal by rectifying and smoothing the input radio signal for mobile communication. This DC voltage signal is input to the comparator 33. The comparator 33 compares the input DC voltage signal with the reference voltage signal REF. Then, the comparison output is supplied as a filter enable signal ES to the changeover switches 632 and 633 of the filter circuit 63 shown in FIG.

  Here, the value of the reference voltage signal REF is set as follows, for example. That is, if the transmission level of the radio signal for mobile communication is larger than the upper limit value of the interference signal level allowed in the tuner unit 61 by the isolation between the mobile communication antenna 1 and the broadcast receiving antenna 8, the filter 631 is used. There is no need to insert. For example, assuming that the upper limit value of the interference signal level allowed in the tuner unit 61 is −10 dBm and the isolation between the mobile communication antenna 1 and the broadcast receiving antenna 8 is 15 dB, transmission of the mobile communication radio signal at this time The level is -5 dBm. Therefore, the value of the DC voltage signal output from the power detection circuit 32 when the transmission level of the mobile communication radio signal is 5 dBm may be set to the value of the reference voltage signal.

  Further, when the reference voltage signal value is fixed to one value, when the ripple component remains in the DC voltage signal output from the transmission power detection circuit 32, the filter 631 and the bypass circuit 634 are frequently switched, and the tuner The broadcast reception signal input to the unit 61 becomes unstable. Therefore, in the second embodiment, the input / output characteristics of the comparator 33 have a hysteresis characteristic. FIG. 4 shows an example of this hysteresis characteristic.

  With this configuration, when a radio signal is transmitted from the mobile communication radio circuit 2 and the value of the DC voltage signal obtained by rectifying and smoothing the transmission power level exceeds the value of the reference voltage signal REF, the comparator A filter enable signal ES of “H” level is supplied from 33 to the selector switches 632 and 633. For this reason, the changeover switches 632 and 633 are switched to the filter 631 side, whereby the filter 631 is inserted between the broadcast receiving antenna 5 and the tuner unit 61. Therefore, the radio signal for mobile communication received by the broadcast receiving antenna 5 together with the broadcast signal is suppressed to a signal level allowed as an interference wave by the filter 631. Therefore, the tuner unit 61 can perform accurate channel selection of the broadcast signal without being affected by the interference by the mobile communication radio signal.

  On the other hand, the value of the DC voltage signal obtained by rectifying and smoothing the transmission power level does not exceed the value of the reference voltage signal REF even during the non-transmission period of the mobile communication radio signal or during the transmission period. The comparator 33 supplies an “L” level filter enable signal ES to the changeover switches 632 and 633. Therefore, the changeover switches 632 and 633 are switched to the bypass circuit 634 side, whereby the broadcast receiving antenna 5 and the tuner unit 61 are directly connected by the bypass circuit 634. Therefore, the terrestrial digital broadcast signal received by the broadcast receiving antenna 5 is input to the tuner unit 61 without being affected by the insertion loss of the filter 631. For this reason, the tuner unit 61 can maintain high reception sensitivity with respect to the terrestrial digital broadcast signal.

  As described above, in the second embodiment, the filter 631 is in the period in which the transmission power level of the radio signal transmitted from the mobile communication radio circuit 2 exceeds the level corresponding to the value of the reference voltage signal REF. It is connected between the broadcast receiving antenna 5 and the tuner unit 61, and on the other hand, it is bypassed during a period when the transmission power level of the radio signal transmitted from the mobile communication radio circuit 2 does not exceed the value corresponding to the reference voltage signal REF. A circuit 634 is connected between the broadcast receiving antenna 5 and the tuner unit 61.

  Therefore, when the transmission power level of the radio signal for mobile communication is large, the radio signal for mobile communication is input to the tuner unit 61 after being suppressed by the filter 631 to a signal level allowed as an interference wave. As a result, the tuner unit 61 can select an accurate channel without being affected by interference caused by a radio signal for mobile communication. On the other hand, when the transmission power level of the mobile communication radio signal is low, the filter 631 is bypassed by the bypass circuit 634, whereby the terrestrial digital broadcast signal is input to the tuner unit 61 without being affected by the insertion loss of the filter 631. Is done. For this reason, the tuner unit 61 can maintain high reception sensitivity with respect to the terrestrial digital broadcast signal.

  Even during the transmission period of the radio signal for mobile communication, the filter 631 is not inserted unless the transmission power level exceeds the level corresponding to the value of the reference voltage signal REF. For this reason, compared with the first embodiment described above, the period during which the filter 631 is connected between the broadcast receiving antenna 5 and the tuner unit 61 can be shortened, thereby reducing the insertion loss of the filter 631. The time during which the influence can be further reduced and the reception sensitivity can be kept high can be lengthened.

  Further, since the comparator 33 has a hysteresis characteristic, even when a ripple component remains in the DC voltage signal, the filter 631 and the bypass circuit 634 are frequently switched, and the broadcast input to the tuner unit 61 is performed. A problem that the received signal becomes unstable can be prevented.

  Further, generally, a mobile communication terminal is provided with a feedback control loop of a transmission power level. In this embodiment, a changeover switch using a DC voltage signal output from the transmission power detection circuit 32 of the existing feedback control loop is used. 632 and 633 are switched. For this reason, it is not necessary to provide a new transmission power detection circuit, which can be realized with a relatively simple circuit configuration in which the comparator 33 is added.

(Third embodiment)
The third embodiment of the present invention relates to a mobile communication terminal having a function of receiving a terrestrial digital broadcast signal, and a guard interval is provided at a certain time interval in the signal format of the terrestrial digital broadcast signal. In particular, the filter enable signal generated in synchronization with the transmission period / non-transmission period of the radio signal for mobile communication is synchronized with the guard interval period.

  The guard interval means that when a broadcast signal is received by the broadcast receiving unit 6 through a plurality of different propagation paths, it is not used for demodulation processing for a predetermined period from the head of the fastest received symbol. This is a section prepared for a certain period so that the symbol immediately before the broadcast signal received with a delay will not interfere.

FIG. 5 is a block diagram showing configurations of a mobile communication radio unit and a broadcast receiving unit of a mobile communication terminal according to the third embodiment of the present invention. In the figure, the same parts as those in FIG.
The transmission control signal SW1 generated from the control unit 8 is input to the D input terminal of the D flip-flop circuit 41. The OFDM demodulator 62 generates a signal indicating the guard interval period of the received broadcast signal, and this guard interval display signal is input to the clock input terminal (CK) of the D flip-flop circuit 41. The D flip-flop circuit 41 latches the transmission control signal SW1 in synchronization with the input timing of the guard interval display signal, and outputs the latched signal from the Q output terminal as a filter enable signal ES.

  Because of such a configuration, for example, a location registration procedure or a handover procedure is executed during reception of a terrestrial digital broadcast signal, and when the mobile communication radio signal transmission period comes along with this, the control unit 8 starts the process shown in FIG. As shown in c), the “H” level transmission control signal SW1 (transmission period display signal) representing the transmission period is generated and input to the D input terminal of the D flip-flop circuit 41.

  On the other hand, in the demodulation process, the OFDM demodulator 62 detects an effective symbol period and a guard interval for each symbol period Ts as shown in FIG. Of these, a signal indicating the guard interval period (guard interval display signal) is generated as shown in FIG. 6B, and this guard interval display signal is input to the clock input terminal (CK) of the D flip-flop circuit 41. Is done.

  As a result, in the D flip-flop circuit 41, the transmission period display signal is latched in synchronization with the guard interval display signal, and the latched signal becomes the filter enable signal ES as shown in FIG. 6 (d). The changeover switches 632 and 633 are supplied. For this reason, the changeover switches 632 and 633 are switched to the filter 631 side.

  Therefore, the filter 631 is inserted between the broadcast receiving antenna 5 and the tuner unit 61. For this reason, the radio signal for mobile communication received by the broadcast receiving antenna 5 together with the broadcast signal is suppressed to a signal level allowed as an interference wave by the filter 631. Therefore, the tuner unit 61 can perform accurate channel selection of the broadcast signal without being affected by the interference by the mobile communication radio signal.

  On the other hand, when the transmission period of the radio signal for mobile communication ends and the transmission control signal SW1 changes to “L” level and a guard interval display signal is generated, it is synchronized with the guard interval display signal. The filter enable signal ES output from the D flip-flop circuit 41 returns to the “L” level as shown in FIG. For this reason, the selector switches 632 and 633 are switched to the bypass circuit 634 side, whereby the broadcast receiving antenna 5 and the tuner unit 61 are directly connected by the bypass circuit 634. Accordingly, the digital terrestrial broadcast signal received by the broadcast receiving antenna 5 is input to the tuner unit 61 without being affected by the insertion loss of the filter 631 during the non-transmission period of the radio signal for mobile communication. For this reason, the tuner unit 61 can maintain high reception sensitivity with respect to the terrestrial digital broadcast signal.

  Moreover, in this embodiment, as described above, the changeover switches 632 and 633 are switched during the guard interval period of the received terrestrial digital broadcast signal. Therefore, it is possible to prevent a change in the carrier phase of the broadcast signal due to the insertion / removal of the filter 631, and to perform stable channel selection and demodulation processing. Incidentally, when the filter 631 is inserted / removed during the effective symbol period of the broadcast signal, the carrier phase of the broadcast signal input to the tuner unit 61 changes abruptly at each insertion / removal, and symbol demodulation is performed in the effective symbol period. Processing may not be possible.

  As described above, in the third embodiment, as in the first embodiment, the filter 631 is inserted between the broadcast receiving antenna 5 and the tuner unit 61 in the transmission period of the radio signal for mobile communication, and the other The detour circuit 634 is inserted during the period. For this reason, in the transmission period of the radio signal for mobile communication, it is possible to reduce the influence of the interference by the radio signal for mobile communication and perform accurate channel tuning processing and demodulation processing, while In the transmission period, it is possible to maintain high reception sensitivity for the terrestrial digital broadcast signal by eliminating the influence of the insertion loss of the filter 631.

  Moreover, in the third embodiment, since the changeover switches 632 and 633 are switched during the guard interval period of the received terrestrial digital broadcast signal as described above, the carrier phase of the broadcast signal by the insertion and removal of the filter 631 is changed. It is possible to prevent change and perform stable channel selection and demodulation processing.

(Other embodiments)
In the third embodiment, the transmission control signal SW1 generated from the control unit 8 is synchronized with the guard interval period and is supplied to the changeover switches 632 and 633 as the filter enable signal ES. However, the present invention is not limited to this. The output signal of the comparator 33 described in the second embodiment is input to the D input terminal of the D flip-flop, and the guard interval period display signal output from the OFDM demodulator 62 is set to D. Input to the clock input terminal of the flip-flop. Then, the output signal of the comparator 33 may be synchronized with the guard interval period and supplied to the changeover switches 632 and 633 as the filter enable signal ES. Even if comprised in this way, the nest which produces an effect similarly to the said 3rd Embodiment is made.

  The means for detecting the transmission power level of the radio signal for mobile communication varies depending on the transmission power level, such as variable gain control information generated by the variable gain control circuit provided in the transmission power amplification circuit section. You may comprise so that it may detect based on a signal. Furthermore, as a signal indicating the transmission period of the radio signal for mobile communication, other signals other than the signal for controlling the power supply to the transmission power amplifier 23 may be used.

  Further, in each of the embodiments, the filter 631 and the bypass circuit 634 are switched. However, the present invention is not limited to this, and an adaptive filter that can variably set the bandpass characteristics is provided. Depending on the case, it may be configured to be variably set.

  Further, although the circuit for receiving a terrestrial digital broadcast signal has been described as an example of the second wireless circuit, wireless LAN (Local Area Network), BT (Blue Tooth) (registered trademark), UWB (Ultra Wide Band), and the like have been described. A wireless unit adopting a short-range wireless data communication standard may be used. In addition, the type and configuration of the mobile communication terminal, the radio access method and the modulation / demodulation method for mobile communication, and the like can be variously modified without departing from the scope of the present invention.

  In short, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in each embodiment. Furthermore, you may combine suitably the component covering different embodiment.

1 is a block diagram showing a configuration of a mobile communication terminal according to a first embodiment of this invention. The circuit block diagram which shows the structure of the broadcast receiving unit which is the principal part of the mobile communication terminal shown in FIG. 1, and the radio | wireless unit for mobile communications. The circuit block diagram which shows the structure of the switching control circuit part which is the principal part of the mobile communication terminal concerning the 2nd Embodiment of this invention. The figure for demonstrating the switching operation | movement timing by the switching control circuit part shown in FIG. 1 is a circuit block diagram showing a configuration of a broadcast receiving unit and a mobile communication radio unit, which are main parts of a mobile communication terminal according to a first embodiment of the present invention. The figure for demonstrating the switching operation | movement timing by the mobile communication terminal shown in FIG. The figure which shows the band pass characteristic of the filter shown in FIG.2 and FIG.5.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Mobile communication antenna, 2 ... Mobile communication radio unit, 3 ... Mobile communication signal processing unit, 4 ... Input / output interface unit, 5 ... Broadcast receiving antenna, 6 ... Broadcast receiving unit, 7 ... Broadcast signal processing unit, DESCRIPTION OF SYMBOLS 8 ... Control unit, 9 ... Memory | storage unit, 11 ... Speaker, 12 ... Microphone, 13 ... Camera, 14 ... Display, 15 ... Power supply circuit, 16 ... Battery, 17 ... Input device, 21 ... Modulation part, 22 ... Frequency conversion part , 23 ... Transmission power amplifier, 24 ... Antenna duplexer (DUP), 25 ... Feed control switch, 31 ... Directional coupler, 32 ... Power detection circuit, 33 ... Comparator, 41 ... D flip-flop circuit, 61 ... Tuner 62, OFDM demodulator, 63 ... Filter circuit, 631 ... Filter, 632, 632 ... Changeover switch.

Claims (5)

A first radio circuit for transmitting a first radio signal for mobile communication;
A second radio circuit for receiving a second radio signal having a frequency band different from that of the first radio signal;
The frequency band of the first radio signal that is arranged on the input side of the second radio circuit and is included in the second radio signal only during a period in which the first radio signal is transmitted from the first radio circuit. A mobile communication terminal comprising: band suppression means for suppressing. A first radio circuit for transmitting a first radio signal for mobile communication;
A second radio circuit for receiving a second radio signal having a frequency band different from that of the first radio signal;
Means for detecting a transmission power level of a first radio signal transmitted from the first radio circuit;
The second radio signal is disposed on the input side of the second radio circuit and is included in the second radio signal only during a period in which the transmission power level of the detected first radio signal exceeds a preset threshold value. A mobile communication terminal comprising band suppression means for suppressing the frequency band of the first radio signal. The band suppression means includes
A first path for inputting the second radio signal to the second radio circuit via a filter circuit having a frequency pass characteristic for suppressing a frequency band of the first radio signal;
A second path for inputting the second radio signal to the second radio circuit, bypassing the filter circuit;
The mobile communication terminal according to claim 1, further comprising a switching circuit that switches between the first route and the second route. The band suppression means includes
When the detected transmission power level of the first radio signal exceeds a preset first threshold value, the second radio signal is thereafter transmitted to the second radio signal via the band suppression means. Means for inputting into the circuit;
In a state where the second radio signal is input to the second radio circuit via the band suppression unit, the detected transmission power level of the first radio signal is greater than the first threshold value. And a means for inputting the second radio signal to the second radio circuit by bypassing the band suppression means when the voltage falls below a second threshold value set smaller. The mobile communication terminal according to claim 2. When the second radio signal comprises an effective symbol period and a guard interval;
The mobile communication terminal according to claim 3, wherein the switching circuit switches between the first route and the second route within the period of the guard interval.

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