JP2011234147A - Communication terminal and signal switching circuit used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication terminal capable of receiving a broadcast and communicating excellently, and a signal switching circuit used therefor.SOLUTION: The communication terminal has a broadcast receiving function to receive a broadcast and a communication function to communicate with a base station, and comprises: an antenna to receive a signal; communication processing means to process a communication signal included in the received signal; broadcast processing means to process a broadcast signal included in the received signal; signal switching means to input the received signal in at least one of the communication processing means or the broadcast processing means; and control means. The control means controls the signal switching means according to presence/absence of starting of the broadcast receiving function, strength of the broadcast signal, a control signal transmitted from the base station.

Description

  The present invention relates to a communication terminal having functions of both communication and broadcast reception, and a signal switching circuit used therefor.

  Cellular phones have undergone generational changes called so-called second generation and third generation, and LTE (Long Term Evolution) called fourth generation and fourth generation communication standards are being studied. A feature of next-generation mobile phone standards such as LTE is that it employs MIMO (Multi Input Multi Output) technology that transmits and receives different data using a plurality of antennas. For example, a cellular phone that supports the LTE standard requires at least two antennas.

  In addition, mobile phones in Japan are equipped with a function to receive 1Seg, a terrestrial digital broadcast, in many models, and there are models overseas that have a broadcast receiving function that matches the broadcasting standards of the region. . In the case of a mobile phone having such a broadcast receiving function, since the frequency band in which the mobile phone communicates is different from the frequency band in which the broadcast signal is transmitted, usually a dedicated antenna is often mounted.

  Therefore, if a mobile phone that supports the next-generation mobile phone standard is to have a broadcast receiving function, it is necessary to add a broadcasting antenna in addition to the plurality of antennas for the MIMO technology. Although it is required to incorporate a large number of antennas in a mobile phone as described above, the size of a housing is limited in a mobile phone that is required to be downsized, and it is difficult to mount a large number of antennas. .

  Patent Document 1 proposes a technique for reducing the number of antennas by sharing communication and broadcast antennas, and connecting an RF (Radio Frequency) signal to a communication or broadcast receiving unit via a changeover switch. .

JP-A-11-122128

  In the configuration described in Patent Document 1, since the RF signal from the antenna is input to either the communication or the broadcast receiving unit by the changeover switch, it is not possible to receive the broadcast while performing the communication.

  An object of this invention is to provide the communication terminal which can communicate favorably, performing broadcast reception, and the signal switching circuit used for this.

  A communication terminal according to the present invention has a broadcast receiving function for receiving a broadcast and a communication function for communicating with a base station, an antenna for receiving a signal, a communication processing means for processing a communication signal included in the received signal, Broadcast processing means for processing a broadcast signal included in the received signal, signal switching means for inputting the received signal to at least one of the communication processing means and the broadcast processing means, and control means are provided. The control means controls the signal switching means according to whether or not the broadcast receiving function is activated, the intensity of the broadcast signal, and the control signal transmitted from the base station. It has a first antenna and a second antenna, and has a broadcast receiving function for receiving broadcasts and a communication function for communicating with base stations.

  ADVANTAGE OF THE INVENTION According to this invention, the communication terminal which can communicate favorably, performing broadcast reception, and the signal switching circuit used for this can be provided.

It is a block diagram which shows the structural example of a communication terminal. It is a block diagram which shows the structural example of RF switch. It is a flowchart which shows an example of a switching control sequence. It is explanatory drawing which showed the connection relationship in a 1st operation state. It is explanatory drawing which showed the connection relationship in a 2nd operation state. It is explanatory drawing which showed the connection relation in the 3rd operation state.

  FIG. 1 is a block diagram illustrating a configuration example of a communication terminal such as a mobile phone. The communication terminal includes a main antenna 21, which is a dedicated communication antenna, an RF switch 3, a diplexer 41, a first LNA (Low Noise Amplifier) 51 for communication, a first reception RF circuit 71, and broadcasting and communication. The sub-antenna 22, which is a shared antenna, the RF switch 1, the broadcast filter 42, the broadcast LNA 52, the tuner 6, the communication filter 43, the communication second LNA 53, and the second reception RF. The circuit 72, the transmission circuit 70, the transmission LNA 50, and the control unit 8 are included. As the communication method, for example, a method based on LTE (Long Term Evolution) standard is used.

  The RF switch 1 includes a first switch 10 that selects and outputs a signal input from one input terminal to any of the three output terminals, a distributor 11 that distributes the input signal in two, a first The second switch 12 that selects and outputs either the input from the switch 10 or the input from the distributor 11 and the input from the first switch 10 or the input from the distributor 11 are selected. And a switch 14 for selecting and outputting the input from the switch 13 to any of the four output terminals.

  In this example, two reception RF circuits of a reception RF circuit 71 and a reception RF circuit 72 are provided, and there are two paths for communication RF signals. For this reason, the main antenna 1 is the only antenna for communication in this example, but high-speed communication by MIMO can be performed as described below.

  First, the reception processing of the first system communication RF signal will be described. When a signal is received by the main antenna 21, the received signal is input to the RF switch 3 and output from any of the four input / output terminals. Here, since the communication terminal performs communication using a plurality of bands having different frequency ranges, the communication RF switch 3 includes an input / output terminal for each band. In the example of FIG. 1, an example of a communication terminal using four bands is shown. However, the number of bands and the number of input / output terminals are not limited to this, and the number of input / output terminals corresponding to the number of bands to be used is not limited thereto. The RF switch 3 is provided.

  The output of the RF switch 3 is input to the diplexer 41. The diplexer 41 includes a diplexer device (DPX) corresponding to the frequency range for each band to be used. This is because the RF characteristics required for the diplexer device are extremely strict, and it is difficult to have characteristics corresponding to all bands with a single device. Therefore, as described above, the RF switch 3 is provided with the number of input / output terminals corresponding to the number of bands, and the RF switch 3 switches the output destination so as to output a signal to the duplexer device corresponding to the band to be used. The signal received by the main antenna 21 includes a communication RF signal and a broadcast RF signal. However, since the frequency range used for broadcasting and communication is different, the signal is filtered by the diplexer 41 to separate the communication RF signal. The

  The received signal input to the diplexer 41 is output to a communication RF signal separated by the communication LNA 51 via a diplexer device corresponding to the band being used. The communication LNA 51 also includes an amplifier for each band, amplifies the communication RF signal by an amplifier corresponding to the band to be used, and outputs the amplified signal to the reception RF circuit 71. The reception RF circuit 71 has a terminal to which a signal is input for each band, and performs switching so as to perform demodulation processing of the RF signal of the band being used, like the diplexer 41 and the like.

  Next, communication RF signal transmission processing will be described.

  The transmission circuit 70 inputs the transmission RF signal to the transmission LNA 50, and the transmission LNA 50 amplifies the input transmission RF signal using an amplifier corresponding to the band being used and outputs the amplified transmission RF signal to the communication diplexer 41. The communication diplexer 41 filters a signal with a diplexer device corresponding to the band being used, and outputs a transmission RF signal to the RF switch 3. The transmission RF signal is transmitted from the main antenna 21 via the RF switch 3.

  The reception processing of the communication RF signal of the second system and the reception processing of the broadcast RF signal will be described.

  The RF signal received by the subantenna 22 is input to the RF switch 1. The RF switch 1 includes a single broadcast-side output terminal that outputs a reception signal to the broadcast filter 42, and four communication-side output terminals that output a reception signal to the communication filter 43. The RF switch 1 switches an output terminal that outputs a signal under the control of the control unit 8. Details of the internal operation of the RF switch 1 will be described later.

  The reception signal output from the broadcast side output terminal of the RF switch 1 is input to the broadcast filter 42. The broadcast filter 42 removes unnecessary out-of-band signals, extracts a broadcast RF signal from the received signal, and outputs the extracted broadcast RF signal to the broadcast LNA 52. The broadcast LNA 52 amplifies the broadcast RF signal and outputs it to the tuner 6. The tuner 6 selects an arbitrary channel from the broadcast RF signal, demodulates it, and outputs a video signal. Note that the filter 42 may be omitted by performing unnecessary out-of-band signal removal processing by the filter 42 in the tuner 6.

  On the other hand, the reception signal output from the communication side output terminal of the RF switch 1 is input to the communication filter 43. The communication filter 43 removes unnecessary out-of-band signals to extract a communication RF signal in a desired frequency range from the received signal, and outputs the extracted communication RF signal to the communication LNA 53. At this time, the communication filter 43, like the diplexer 41, is difficult to satisfy the RF characteristics required by a single filter device, and therefore includes a filter device corresponding to the frequency range for each band to be used. The switch 14 switches the output destination so as to output the received signal to the filter device corresponding to the band to be used. The communication LNA 53 also includes an amplifier for each band, and an amplifier corresponding to the band being used amplifies the received RF signal and outputs it to the reception RF circuit 72. The reception RF circuit 72 has a terminal for inputting a signal for each band, and performs a demodulation process of the RF signal of the band used.

  The operation of the RF switch 1 will be described with reference to FIGS. The RF switch 1 switches the switch 10 and the like so as to switch to three operation states according to broadcasting and communication states.

  In the first operation state, the received signal input from the sub-antenna 22 is output to the broadcast filter 42 as it is without being distributed. In this case, the control unit 8 switches the switch 10 in the RF switch 1 to output a signal to the switch 12 and switches the switch 1 to input a signal from the switch 10.

  The connection relationship in this case is shown in FIG. A signal received by the sub-antenna 22 is output from the RF switch 1 to the broadcast filter 42, and a broadcast RF signal is extracted. The extracted broadcast RF signal is amplified by the broadcast LNA 52, the broadcast RF signal is demodulated by the tuner 6, and a video signal is output.

  On the other hand, a signal received by the main antenna 21 is input to a communication diplexer device corresponding to a band used for communication by switching the switch 3. The communication RF signal separated by the communication diplexer device is amplified by the first communication LNA 51 and then demodulated by the first reception RF circuit 71. The transmission RF signal output from the transmission circuit 70 is amplified by the transmission LNA 50 and output to the communication diplexer 41.

  In this way, in the first operating state, the received signal is not distributed by the sub-antenna 22, so the signal level does not decrease except for the loss at the switch 10 or the like, and is almost the same as when a dedicated antenna for broadcasting is provided. Reception performance can be ensured. As for the communication function, MIMO reception cannot be performed and the communication speed is lowered, but the communication itself can be continued without any problem by the communication RF signal received by the main antenna 21.

  In the second operation state, the received signal input from the sub-antenna 22 is output to the communication filter 43 as it is without being distributed. In this case, the control unit 8 switches the switch 10 in the RF switch 1 to output a signal to the switch 13 and switches the switch 13 to input a signal from the switch 10. When an RF signal is input from the switch 13 to the switch 14, the switch 14 switches the output destination to the communication filter 43 so as to output a signal to a filter device corresponding to the communication band being used.

  The connection relationship in this case is shown in FIG. The reception signal output to the communication filter 43 is amplified by the communication LNA 53, and the communication RF signal is demodulated by the second reception RF circuit 72. Note that the signal received by the main antenna 21 is subjected to reception processing in the same manner as in the first operation state.

  As described above, in the second operation state, the signal received by the sub-antenna 22 is not distributed. Therefore, the signal level does not decrease except for the loss at the switch 10 or the like, and the case of having the dedicated antenna for communication and Almost the same reception performance can be ensured. In this case, MIMO reception using the communication RF signal received by the main antenna 21 and the communication RF signal received by the sub antenna 22 can be performed, and the communication speed can be increased.

  In the third operation state, the signal input from the sub-antenna 22 is distributed within the RF switch 1 and output to both the broadcast filter 42 and the communication filter 43. In this case, the control unit 8 switches the switch 10 in the RF switch 1 to output a signal to the distributor 11, and switches the switch 12 and the switch 13 to input signals from the distributor 11, respectively. The distributor 11 divides the received signal into two and outputs it to the switches 12 and 13. When a signal is input from the switch 13 to the switch 14, the output destination to the communication filter 43 is switched so that the signal input to the filter device corresponding to the communication band being used is output.

  The connection relationship in this case is shown in FIG. The RF signal output to the broadcast filter 42 is amplified by the broadcast LNA 52, and the tuner 6 demodulates the broadcast RF signal. On the other hand, the communication RF signal output to the communication filter 43 is amplified by the communication LNA 53 and demodulated by the second reception RF circuit 72.

  As described above, in the third operation state, the signal received by the sub-antenna 22 is distributed and input to the tuner 6 and the second reception RF circuit 72. In this case, the signal level input to each of the signals is lowered, but the broadcast can be received while performing the MIMO reception. As for communication, although the communication state is slightly deteriorated compared to the second operation state, the communication speed can be increased compared to the first operation state in which MIMO reception cannot be used.

  FIG. 3 illustrates an example of a control sequence for switching the three operation states described above. This sequence is executed by the control unit 8 based on a program stored in a memory (not shown) when the power of the communication terminal is turned on.

  First, it is determined whether or not the broadcast reception function of the communication terminal is turned on (S31). This determination is made based on, for example, whether an application for receiving a broadcast is activated.

  If it is determined that the broadcast is not being received (No at S31), a process for switching to the second operation state is performed. Specifically, the power of the second reception RF circuit 72 is turned on (S301), and the RF switch 1 is switched so that the output signal from the sub-antenna 22 is input to the reception RF circuit 72 (S302). By controlling in this way, MIMO reception becomes possible. In the second operation state, it is desirable to control not to supply power to the configuration used for broadcast reception such as the tuner 6 so as to reduce the power consumption of the terminal. If a predetermined time has elapsed after switching in S302, the process returns to S31, and it is determined again whether or not the broadcast is being received. Alternatively, the stop of the broadcast receiving application may be used as a trigger for the determination in S31.

  If it is determined in S31 that the broadcast reception function is ON, the tuner 6 and the reception RF circuit 72 are turned on (S32, S33), and the tuner 6 and the reception RF circuit 72 receive the signal via the sub antenna 22. The RF switch 1 is switched so that the signal is distributed and input (S34).

  The received signal distributed by the RF switch 1 is input to the broadcast filter 42, and the broadcast RF signal is extracted. When the broadcast RF signal amplified by the broadcast LNA 52 is input, the tuner 6 determines the signal level of the broadcast RF signal (S35).

  When the signal level is equal to or higher than the first threshold value M, the power of the reception RF circuit 72 is turned on to switch to the third operation state (S37), and the tuner 6 and the reception RF circuit 72 receive the signal by the sub antenna 22. The RF switch 1 is switched so that the received signal is distributed and input (S38). Note that S37 and S38 are omitted when the power of the reception RF circuit 72 is already ON or when the RF switch 1 is switched to correspond to the third operation state.

  The case where the signal level is equal to or higher than the first threshold value M is a state in which there is a high possibility that the error-free state can be maintained with sufficient margin in the tuner 6 even when the received signal is divided into two and the signal level decreases. . The first threshold M is set, for example, as a value obtained by adding a certain margin to a reference value that is error-free. The error-free reference value is obtained from the theoretical values such as the received electric field strength, RSSI (Received Signal Strength Indicator), and C / N (Carrier to Noise) ratio based on the transmission parameters of the broadcast RF signal. And Any value can be extracted from the tuner 6 as a value indicating the reception state and used for control. The margin value is set in order to continue error-free reception stably as long as the reception status of the receiving terminal does not change significantly, and the target error-free time rate is determined and set as a fading margin that satisfies it can do.

  When the signal level is lower than the second threshold value N in S35, the power of the reception RF circuit 72 is turned off to switch to the first operation state (S39), and the signal received by the sub antenna 22 is received by the tuner 6. The RF switch 1 is switched so as to be input (S40). The case where the signal level is less than the second threshold value N is a state where there is a high possibility that the error-free state cannot be maintained when the received signal is divided into two. The second threshold value N is, for example, a reference value that is error-free. Set.

  When the signal level is equal to or higher than the second threshold value N and lower than the first threshold value M, that is, the error-free state can be maintained when the RF signal is divided into two, but the margin is determined to be small. The process proceeds to S36.

  In S36, it is determined whether MIMO reception is necessary. If MIMO reception is not required, the process proceeds to S39. On the other hand, when the MIMO reception is required, the process proceeds to S37 in order to perform the MIMO reception operation while performing the broadcast reception.

  Hereinafter, the details of the determination method in S36 will be described by taking as an example a case where the communication terminal uses a communication method based on the LTE standard.

  The communication speed in the LTE standard is determined by a number of transmission parameters such as the number of channels (number of layers) created by spatial multiplexing by MIMO, the modulation scheme and the error correction code format, and the base station uses the number of layers and the code used for transmission processing. A word or the like can be selected according to the transmission environment. The communication terminal transmits information such as channel quality indication (CQI), precoding matrix indicator (PMI), and rank indication (RI) as parameters indicating the reception status of the terminal, and the base station uses the information as a basis. The number of layers is determined, and a control signal indicating the determined number of layers is transmitted to the communication terminal. In S36, it is detected whether or not to perform MIMO reception using the control signal received from the base station. That is, when the number of layers is 1, it is assumed that MIMO reception is unnecessary, and when the number of layers is 2 or more, MIMO reception is required.

  Note that the communication terminal, for example, stores a memory (not shown) that stores an application program for reproducing data output from the reception RF circuits 71 and 72, and buffers the output data before reproduction using the application program. A buffer (not shown) for ringing is provided, and the control unit 8 sets an RI value in accordance with the amount of buffered data and performs control so as to transmit it to the base station. When streaming playback is performed using a communication line, smooth playback cannot be performed when the communication speed is lower than the bit rate of the playback stream. Therefore, when the control unit 8 detects that the buffered data amount is less than or equal to the predetermined amount and has decreased, the control unit 8 considers that the communication speed is insufficient and requests the base station to receive two or more data by MIMO. Send RI value. On the other hand, when the amount of buffered data is large, RI = 1 or a value lower than the previously notified RI value is communicated.

  After switching the RF switch 1 in S38 and S40, when a predetermined time has elapsed, it is determined whether or not the broadcast function is turned off (S41), and if not, the process proceeds to S35. On the other hand, if the broadcasting function is turned off, the tuner 6 is turned off (S42), and the process proceeds to S31.

  As described above, the communication terminal is provided with the RF switch having a distributor, and the output of the signal received by the sub-antenna is switched according to the broadcasting and communication conditions. If the reception state of the broadcast RF signal is good and high-speed communication is required, the broadcast reception and the high-speed reception by MIMO are compatible. If the reception state of the broadcast RF signal is not good, the tuner is not performed and the MIMO reception is not performed. Give priority to the reception status of. Further, when broadcast reception is not performed, normal MIMO reception is performed without performance degradation. By controlling in this way, it is possible to perform communication satisfactorily while performing broadcast reception.

  Note that the configuration shown in FIG. 1 and the sequence shown in FIG. 3 are examples, and the present invention is not limited to these. For example, the reception strength determination of the broadcast signal in S35 of FIG. 3 is determined in two stages, or the operation state is switched using either the reception strength of the broadcast signal or the necessity of MIMO communication. The step may be omitted. However, in order to more appropriately perform control according to broadcasting and communication conditions, it is desirable to perform switching control using both the reception intensity of broadcast signals and the necessity of MIMO communication. Further, not only the reception intensity of the broadcast signal and the necessity of MIMO communication but also other steps such as using other determinations may be added.

  Further, the present invention is not limited to the RF switch 1 shown in FIG. 1, and other signal switching circuits such as the RF switch 100 shown in FIG. 2 may be used. FIG. 2 is a block diagram showing the configuration of the RF switch. The RF switch 100 selects a signal input from one input terminal to either one of the two output terminals, outputs the first switch 101, the distributor 11, and the input from the first switch 101. Switch 105 that selects and outputs one of the two output terminals, and a second switch that selects and outputs either the input from the fifth switch 105 or the input from the distributor 11 12, a third switch 13 that selects and outputs either the input from the fifth switch 105 or the input from the distributor 11, and the input from the fifth switch 105 or the input from the distributor 11 It comprises a third switch 13 that selects and outputs either one, and a switch 14.

DESCRIPTION OF SYMBOLS 1 RF switch 3 RF switch 6 Broadcast tuner 8 Control part 21 Main antenna 22 Subantenna 41 Deplexer 42 Broadcast filter 43 Communication filter 50 Transmission LNA
51 LNA for first communication
52 LNA for broadcasting
53 Second LNA for communication
70 Transmission Circuit 71 First Reception RF Circuit 72 Second Reception RF Circuit

Claims (8)

A communication terminal comprising a first antenna and a second antenna, having a broadcast receiving function for receiving a broadcast and a communication function for communicating with a base station,
First communication filter means for separating a communication signal from signals received by the first antenna;
First demodulation means for demodulating the communication signal output from the first filter means;
Second communication filter means for separating a communication signal from signals received by the second antenna;
Second demodulation means for demodulating the communication signal output from the second filter means;
Broadcast filter means for separating a broadcast signal from signals received by the second antenna;
A tuner for demodulating the broadcast signal output from the broadcast filter means;
Signal switching means for inputting a signal received by the second antenna to at least one of the second communication filter means and the broadcast filter means;
Control means for controlling the signal switching means,
The control means controls the signal switching means to output the signal received by the second antenna to the second communication filter means when the broadcast receiving function is not activated, and When the function is activated, the signal received by the second antenna is sent to the second communication filter and the broadcast filter or the broadcast filter according to the intensity of the broadcast signal demodulated by the tuner. A communication terminal characterized by controlling the signal switching means to input. A communication terminal comprising a first antenna and a second antenna, having a broadcast receiving function for receiving a broadcast and a communication function for communicating with a base station,
First communication filter means for separating a communication signal from signals received by the first antenna;
First demodulation means for demodulating the communication signal output from the first filter means;
Second communication filter means for separating a communication signal from signals received by the second antenna;
Second demodulation means for demodulating the communication signal output from the second filter means;
Broadcast filter means for separating a broadcast signal from signals received by the second antenna;
A tuner for demodulating the broadcast signal output from the broadcast filter means;
Signal switching means for inputting a signal received by the second antenna to at least one of the second communication filter means and the broadcast filter means;
Control means for controlling the signal switching means,
The control means controls the signal switching means to output the signal received by the second antenna to the second communication filter means when the broadcast receiving function is not activated, and When the function is activated, a signal received by the second antenna is input to the second communication filter and the broadcast filter or the broadcast filter in accordance with a control signal transmitted from the base station. The communication terminal is characterized by controlling the signal switching means. A communication terminal comprising a first antenna and a second antenna, having a broadcast receiving function for receiving a broadcast and a communication function for communicating with a base station,
First communication filter means for separating a communication signal from signals received by the first antenna;
First demodulation means for demodulating the communication signal output from the first filter means;
Second communication filter means for separating a communication signal from signals received by the second antenna;
Second demodulation means for demodulating the communication signal output from the second filter means;
Broadcast filter means for separating a broadcast signal from signals received by the second antenna;
A tuner for demodulating the broadcast signal output from the broadcast filter means;
Signal switching means for inputting a signal received by the second antenna to at least one of the second communication filter means and the broadcast filter means;
Control means for controlling the signal switching means,
The control means controls the signal switching means to output the signal received by the second antenna to the second communication filter means when the broadcast receiving function is not activated, and When the function is activated, a signal received by the second antenna according to the intensity of the broadcast signal demodulated by the tuner and the control signal transmitted from the base station is converted into the second communication filter. And the broadcast filter, or the signal switching means for controlling the signal switching means to input to the broadcast filter.   The communication terminal according to claim 1, wherein the tuner includes an intensity determination unit that determines reception intensity of the demodulated broadcast signal. A communication terminal comprising an antenna, having a broadcast receiving function for receiving a broadcast and a communication function for communicating with a base station,
Communication processing means for processing a communication signal included in a signal received by the antenna;
Broadcast processing means for processing a broadcast signal included in the signal received by the antenna;
Signal switching means for inputting a signal received by the antenna to at least one of the communication processing means and the broadcast processing means;
Control means for controlling the signal switching means,
The control means controls the signal switching means so as to output a signal received by the antenna to the communication processing means when the broadcast receiving function is not activated, and the broadcast receiving function is activated. The signal received by the antenna in accordance with the intensity of the broadcast signal processed by the broadcast processing means or the control signal transmitted from the base station, the communication processing means and the broadcast processing means, or the broadcast A communication terminal for controlling the signal switching means to input to a processing means.   The communication terminal according to claim 2, 3 or 5, wherein the control signal has information indicating the number of layers used in MIMO communication.   The communication terminal according to claim 1, wherein the signal switching unit includes a distributor that distributes and outputs an input signal. A signal switching circuit used in a communication terminal,
An input unit for receiving a signal received by the antenna of the communication terminal;
A first output unit for outputting a signal to a first receiving circuit of the communication terminal;
A second output unit for outputting a signal to a second receiving circuit of the communication terminal;
A distribution unit that distributes and outputs a signal input to the input unit to the first output unit and the second output unit;
With
In response to control from the control unit of the communication terminal, the signal input to the input unit is output to one of the first output unit and the second output unit, or the distribution unit is used to A signal switching circuit that performs switching so as to output to both the first output unit and the second output unit.

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