Wireless communication device and wireless communication system

Abstract

To apply a radio communication device, for example a device for specified low-power radio system to a system, for example, a disaster prevention radio system.SOLUTION: A radio communication device of the invention includes: a first radio reception part for radio-receiving a radio signal modulated according to an audio signal by a first channel and demodulating it to a first audio signal; a second radio reception part for radio-receiving a radio signal modulated according to an audio signal by a second channel and demodulating it to a second audio signal; an audio output part for outputting the first audio signal and the second audio signal by selectively switching them by interlocking with the start of radio reception by the first and the second radio reception parts, or adding and outputting them; and a first control part for controlling the first and the second radio reception parts. The first control part controls the audio output part so as to switch to and output the second audio signal when the second radio reception part radio-receives the radio signal while the first radio reception part is radio-receiving the radio signal.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a wireless communication device that complies with, for example, standards for radio equipment for specified low-power radio stations and radio telephones, and a wireless communication system that includes the wireless communication device. [Background technology]

[0002] In recent years, as we have been hit by natural disasters such as earthquakes and typhoons, some local governments have introduced disaster prevention radio systems or disaster prevention administrative radio systems (hereinafter referred to as disaster prevention radio systems) and have installed dedicated receivers in every household.However, while the disaster prevention radio system must "reach residents without fail," it requires the allocation of dedicated frequencies from the Ministry of Internal Affairs and Communications to prevent interference, and "complex line design" and other factors that make it difficult, time-consuming, and costly to introduce the system, making it difficult to implement.

[0003] For example, by operating a disaster prevention radio system using specific low-power radio equipment, it can be operated in a limited area, but there is no need to apply to government agencies and the actual equipment can be prepared relatively inexpensively, lowering the hurdle to introducing the system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4828396 [Non-patent literature]

[0005] [Non-Patent Document 1] Association of Radio Industries and Businesses, "Standard for Radio Equipment for Specified Low-Power Radio Stations and Radio Telephones," RCR-STD-20, Version 5.0, revised September 28, 2020 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there were the following issues:

[0007] National technical standards have been established for the purpose of making effective use of frequencies and avoiding interference with other users, and the "Standards for Radio Equipment for Specified Low-Power Radio Stations and Radio Telephones" have also been established in Non-Patent Document 1 for the purpose of ensuring the appropriate quality and compatibility of radio equipment, and for the convenience of radio equipment manufacturers and users. These specified low-power radio stations are widely used throughout the country because they do not require a radio station license. However, the standard stipulates that when configuring a radio communication device with an antenna power of, for example, 10 mW, "it must have the function of automatically limiting communication time to within three minutes, and in that case, not to communicate again until two seconds have elapsed."

[0008] Furthermore, on page 13 of Non-Patent Document 1, the following is defined regarding "carrier sense" (former Ministry of Posts and Telecommunications Notification, No. 49 of 1989): Hereinafter, this will be referred to as "career sense regulations."

[0009] (3) Career Sense Radio equipment shall be equipped with a carrier sense function. Carrier sense means that, when radio waves from another radio station are received prior to the establishment of a radio communication line, radio waves of the same frequency as the radio waves emitted by that radio station (in the case of duplex and semi-duplex systems, the transmission frequency corresponding to the receiving frequency) shall not be emitted.

[0010] 11 is a timing chart showing an example of operation for explaining the problem in a conventional wireless communication system. This wireless communication system is configured with a wireless transmitter and a wireless receiver.

[0011] In Figure 11, the wireless transmitter transmits an audio signal intermittently and repeatedly for a predetermined time limit of three minutes, and performs carrier sense (CS) before each wireless transmission. In response, the wireless receiver receives the wireless signal from the wireless transmitter, demodulates it, and outputs the audio signal. As a result, the wireless receiver receives the audio signal intermittently, causing the audio signal to be interrupted.

[0012] In other words, as mentioned above, when transmitting with an antenna power of 10 mW in a specific low-power radio system, there is a transmission time limit of 3 minutes, and it was not possible to introduce it into a disaster prevention radio system, which requires continuous radio transmission for long periods of time without interruption of the audio signal.

[0013] The object of the present invention is to solve the above problems and to provide a wireless communication device that does not interrupt the audio signal even if the audio signal transmission time exceeds a predetermined time limit, such as three minutes, when the wireless communication device of a specified low-power wireless system is applied to, for example, a disaster prevention wireless system, and a wireless communication system equipped with the wireless communication device. [Means for solving the problem]

[0014] A wireless communication device according to a first aspect of the present invention comprises: a first wireless receiving unit that wirelessly receives a wireless signal modulated in accordance with an audio signal on a first channel and demodulates the wireless signal into a first audio signal; a second wireless receiving unit that wirelessly receives, via a second channel, a wireless signal modulated in accordance with the audio signal and demodulates the wireless signal into a second audio signal; an audio output unit that selectively switches between and outputs the first audio signal and the second audio signal in conjunction with the start of wireless reception by the first and second wireless receiving units, or adds and outputs the first audio signal and the second audio signal; a first control unit that controls the first and second wireless receiving units, The first control unit controls the audio output unit to switch to and output the second audio signal when the second wireless receiving unit receives a radio signal during wireless reception by the first wireless receiving unit.

[0015] A wireless communication device according to a second aspect of the present invention comprises: a first wireless transmitting unit that wirelessly transmits a wireless signal modulated in accordance with an audio signal over a first channel within a predetermined first time limit and intermittently; a second wireless transmission unit that is a wireless transmission unit different from the first wireless transmission unit, and that wirelessly transmits a wireless signal modulated in accordance with the audio signal on a second channel within a predetermined second time limit and intermittently; and a second control unit that controls the first and second wireless transmission units, wherein the second control unit starts wireless transmission of the second wireless transmission unit before wireless transmission of the first wireless transmission unit ends due to the first time limit, thereby controlling wireless transmission of the wireless signal modulated according to the audio signal by the first wireless transmission unit and wireless transmission of the wireless signal modulated according to the audio signal by the second wireless transmission unit to be performed simultaneously for a predetermined time.

[0016] A wireless communication system according to a third aspect of the present invention comprises: a wireless communication device according to the first aspect of the present invention; and the wireless communication device according to the second aspect of the present invention. [Effects of the Invention]

[0017] Therefore, according to the wireless communication device etc. of the present invention, it is possible to provide a wireless communication device that can be applied to, for example, a specified low-power wireless system, for example, a disaster prevention wireless system, and a wireless communication system including the wireless communication device. In particular, when a wireless communication device of, for example, a specified low-power wireless system is applied to, for example, a disaster prevention wireless system, the voice signal will not be interrupted even if the voice signal transmission time exceeds a predetermined time limit, for example, three minutes. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram showing an example of the configuration of a wireless transmitting / receiving device for a wireless communication system according to a first embodiment. [Figure 2] 2 is a block diagram showing an example of the configuration of a wireless receiving device that receives a wireless signal from the wireless transmitting / receiving device of FIG. [Figure 3A] 4 is a flowchart showing a first part of a transmission / reception control process executed by the wireless transmission / reception device of FIG. [Figure 3B]10 is a flowchart showing a second part of the transmission and reception control process executed by the wireless transmission and reception device of FIG. [Figure 4A] 3 is a flowchart showing a first part of a reception control process executed by the wireless receiving device of FIG. 2. [Figure 4B] 3 is a flowchart showing a second part of the reception control process executed by the wireless receiving device of FIG. [Figure 5] 3 is a timing chart showing an example of operation of a wireless communication system including the wireless transmitting / receiving device of FIG. 1 and the wireless receiving device of FIG. 2. [Figure 6A] 10 is a flowchart showing a first part of a transmission / reception control process executed by a wireless transmission / reception device for a wireless communication system according to a second embodiment. [Figure 6B] 10 is a flowchart showing a second part of the transmission and reception control process executed by the wireless transmission and reception device according to the second embodiment. [Figure 7A] 10 is a flowchart showing a first part of a reception control process executed by a wireless reception device according to the second embodiment. [Figure 7B] 10 is a flowchart showing a second part of the reception control process executed by the wireless reception device according to the second embodiment. [Figure 8] FIG. 11 is a block diagram showing an example of the configuration of a wireless receiving device for a wireless communication system according to a third embodiment. [Figure 9A] 11 is a flowchart showing a first part of a transmission / reception control process of a wireless transmission / reception device used in a wireless communication system according to a third embodiment. [Figure 9B] 11 is a flowchart showing a second part of the transmission and reception control process of the wireless transmission and reception device used in the wireless communication system according to the third embodiment. [Figure 10A] 9 is a flowchart showing a first part of a reception control process executed by the wireless receiving device of FIG. 8. [Figure 10B] 9 is a flowchart showing a second part of the reception control process executed by the wireless receiving device of FIG. 8. [Figure 11]10 is a timing chart showing an example of operation for explaining a problem in a wireless communication system according to a conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings, in which the same or similar components are designated by the same reference numerals.

[0020] (Embodiment 1) Fig. 1 is a block diagram showing an example of the configuration of a wireless transmitting / receiving device for a wireless communication system according to embodiment 1. Fig. 2 is a block diagram showing an example of the configuration of a wireless receiving device that receives a wireless signal from the wireless transmitting / receiving device of Fig. 1. The wireless communication system is, for example, a disaster prevention wireless system, and is configured with the wireless transmitting / receiving device of Fig. 1 and the wireless receiving device of Fig. 2 that are connected to each other by a wireless line, and each device is a wireless communication device that complies with the standard for radio equipment for specified low-power radio stations and radio telephones, with an antenna transmission power of, for example, 10 mW or less.

[0021] 1, the wireless transmitting / receiving device is configured to include antennas 1 to 3, modulation / transmission units 11 and 12, a reception / demodulation unit 13, an operation unit 14 having a PTT (Push To Talk) key 14p, a microphone 15, an audio signal input unit 16, an audio signal amplifier 17, an audio signal level measurement unit 18, a received wireless signal level measurement unit 19, and a control unit 10 that controls these processing units. Here, the antennas 1 to 3 may be configured to include, for example, at least one or two antennas, and may be shared by a bandpass filter or a circulator. The audio signal input unit 16 and the audio signal level measurement unit 18 are processing units used in a modified example of the first embodiment, which will be described in detail later.

[0022] 1, in order to perform carrier sense (CS) on a predetermined channel among a plurality of channels, a reception demodulation unit 13 receives a radio signal received by an antenna 3, performs low-noise amplification, low-band frequency conversion, intermediate amplification, etc., and outputs the processed signal to a reception radio signal level measurement unit 19. The reception channel of the reception demodulation unit 13 is controlled by a control unit 10. The reception radio signal level measurement unit 19 compares the input signal with a predetermined threshold value to determine whether a radio signal is received for the carrier sense (CS) on a predetermined channel among a plurality of channels, and outputs a determination result signal to the control unit 10.

[0023] The operation unit 14 has a PTT key 14p, which is a transmission key for issuing a transmission instruction, and when the PTT key 14p is turned on, outputs a control signal indicating this to the control unit 10. Voice input to the microphone 15 is converted into an audio signal, which is then amplified by an audio signal amplifier 17 and output to the modulation transmission units 11 and 12. The modulation transmission units 11 and 12 each modulate a carrier signal of a predetermined channel out of multiple channels in accordance with the input voice signal to generate a modulated radio signal, which is power-amplified and then radiated from the antennas 1 and 2. The transmission channels of the modulation transmission units 11 and 12 are controlled by the control unit 10.

[0024] The modulation transmission units 11 and 12 comply with the radio equipment standard for specified low-power radio station radio telephones, with an antenna transmission power of, for example, 10 mW or less, and after performing carrier sense (CS) to confirm that there is no radio signal from another radio communication device on the channel to be transmitted, they intermittently transmit radio signals using that channel for a limited time (a maximum transmission time, for example, 3 minutes (or 5 minutes). Transmission may be within the time limit. The transmission time limits for the modulation transmission units 11 and 12 may be the same or different). After modulation transmission unit 11 transmits, when modulation transmission unit 12 next transmits, it performs radio transmission on a channel different from that of modulation transmission unit 11, starting from a time, for example, 5 seconds (a predetermined time that is sufficiently shorter than the 3-minute limit) before the time 3 minutes after the transmission time (time limit) of modulation transmission unit 11 has elapsed (thus, carrier sense (CS) is performed from the time before that).

[0025] The control unit 10 includes three-minute timers T1 and T2, which are set to a timeout period (transmission time limit) of, for example, three minutes at the time of reset, and then subtract the timeout period held at the start of timeout period from the timers T1 and T2. The control unit 10 controls the operation of each of the processing units 11 to 18 by using the three-minute timers T1 and T2 to execute the transmission / reception control process shown in Figures 3A and 3B, which will be described later, based on control signals from each of the processing units 14, 18, and 19.

[0026] 2, the wireless receiving device includes antennas 4 and 5, reception demodulation units 21 and 22, an audio signal switching unit 23, an audio signal amplifier 24, and a speaker 25. Here, the antennas 4 and 5 may be configured as a single shared antenna.

[0027] 2, reception demodulation units 21 and 22 each receive a radio signal received by antennas 4 and 5 on a predetermined channel from among a plurality of channels, and after performing processing such as low-noise amplification, low-band frequency conversion, and intermediate frequency amplification, demodulate the processed signal into an audio signal and output it to audio signal switching unit 23. Note that each reception channel of reception demodulation units 21 and 22 is controlled by control unit 20. Audio signal switching unit 23 selectively switches one of two input audio signals and outputs it to audio signal amplification unit 24. Audio signal amplification unit 24 amplifies the input audio signal and outputs it to speaker 25, where it is output as audio. Control unit 20 controls the operation of each processing unit 21 to 23 by executing reception control processing shown in FIGS. 4A and 4B, which will be described later.

[0028] The receiving and demodulating unit 22 in Figure 2 starts wireless reception on another channel 2 at a time (times t2 and t4 in Figure 5) that is, for example, 5 seconds before the time when 3 minutes have elapsed since the time of wireless reception by the receiving and demodulating unit 21 (times t1, t3, and t5 in Figure 5), and the audio signal switching unit 23 switches the output from the audio signal of channel 1 to the audio signal of channel 2 at time t2, so that the audio signal can be output without interruption for more than 3 minutes using the two receiving and demodulating units 21 and 22.

[0029] 3A and 3B are flowcharts showing the transmission / reception control process executed by the wireless transmission / reception device of FIG.

[0030] In step S1 of FIG. 3A, the PTT 14p is awaited to be turned on (or, in a modified example described later, the voice signal is awaited from the voice signal input unit 16), the receiver / demodulator unit 13 enters a reception standby state on channel 1 for carrier sense (CS), and the three-minute timers T1 and T2 are reset to 0 seconds. Next, in step S2, it is determined whether the three-minute timer T1 has a time value of 0 seconds. If the result is YES, the process proceeds to step S3, and if the result is NO, the process proceeds to step S4. In step S4, it is determined whether the PTT key 14p is on or there is a voice input. If the result is YES, the process proceeds to step S6, and if the result is NO, the process proceeds to step S5. In step S5, the modulator / transmitter units 11 and 12 stop wireless transmission and then return to step S2.

[0031] In step S6, it is determined whether the time count of the three-minute timer T2 is five seconds or less, and if the result is YES, the process proceeds to step S7, while if the result is NO, the process returns to step S2. In step S7, the reception / demodulation unit 13 performs carrier sense (CS) to determine whether there is an input, for example, on channel 1, and if the result is YES, the process returns to step S2, while if the result is NO, the process proceeds to step S8. In step S8, the modulation / transmission unit 11 starts wireless transmission on channel 1, and the reception / demodulation unit 13 waits for wireless reception on channel 2 for carrier sense (CS), and in step S9, the three-minute timer T1 starts timing, and the process proceeds to step S11 in FIG. 3B.

[0032] In step S11 of Fig. 3B, it is determined whether the time count of the 3-minute timer T2 is 0 seconds, and if YES, the process proceeds to step S12, while if NO, the process proceeds to step S13. In step S12, the modulation transmission unit 12 stops wireless transmission, and the process proceeds to step S13. In step S13, it is determined whether the PTT key 14p is on or whether there is voice input, and if YES, the process proceeds to step S15, while if NO, the process proceeds to step S14. In step S14, the modulation transmission units 11, 12 stop wireless transmission, and then return to step S2 of Fig. 3A.

[0033] In step S15, it is determined whether the time count of the three-minute timer T1 is five seconds or less, and if YES, the process proceeds to step S16, while if NO, the process returns to step S11. In step S16, the receiver-demodulator 13 performs carrier sensing (CS) to determine whether there is an input, for example, on channel 2, and if YES, the process returns to step S11, while if NO, the process proceeds to step S17. In step S17, the modulator-transmitter 12 starts wireless transmission on channel 2, and the receiver-demodulator 13 waits for wireless reception on channel 1 for carrier sensing (CS), and in step S18, the three-minute timer T2 starts timing, and the process returns to step S2 of FIG. 3A.

[0034] 4A and 4B are flowcharts showing the reception control process executed by the wireless receiving device of FIG.

[0035] 4A, the reception / demodulation unit 21 waits for wireless reception via an incoming signal, for example, on channel 1, and the reception / demodulation unit 22 waits for wireless reception via an incoming signal, for example, on channel 2. Next, in step S22, the reception / demodulation unit 21 determines whether or not there is an incoming wireless signal, and if YES, the process proceeds to step S23, while if NO, the process returns to step S22. In step S23, the audio signal switching unit 23 switches to select output of an audio signal from the reception / demodulation unit 21, and starts outputting the received audio signal in step S24.

[0036] In step S25, the reception / demodulation unit 21 determines whether or not a wireless signal has been received, and if the answer is YES, the process proceeds to step S27, whereas if the answer is NO, the process proceeds to step S26. In step S26, the output of the received audio signal is stopped, and the process returns to step S22. In step S27, the reception / demodulation unit 22 determines whether or not a wireless signal has been received, and if the answer is YES, the process returns to step S25, whereas if the answer is NO, the process proceeds to step S28. Also, in step S28, the reception / demodulation unit 21 determines whether or not a wireless signal has been received, and if the answer is YES, the process proceeds to step S30, whereas if the answer is NO, the process proceeds to step S29. In step S29, the output of the received audio signal is stopped, and the process returns to step S22. In step S30, the reception / demodulation unit 22 determines whether or not a wireless signal has been received, and if the answer is YES, the process proceeds to step S31 of FIG. 4B, whereas if the answer is NO, the process returns to step S28.

[0037] In step S31 of FIG. 4B, the audio signal switching unit 23 switches to select output of an audio signal from the reception / demodulation unit 22, and in step S32, it is determined whether or not a wireless signal is received by the reception / demodulation unit 22. If the determination is YES, the process proceeds to step S34, and if the determination is NO, the process proceeds to step S33. In step S33, the output of the received audio signal is stopped, and the process returns to step S22 of FIG. 4A. In step S34, it is determined whether or not a wireless signal is received by the reception / demodulation unit 21. If the determination is YES, the process returns to step S32, and if the determination is NO, the process proceeds to step S35. Also, in step S35, it is determined whether or not a wireless signal is received by the reception / demodulation unit 22. If the determination is YES, the process proceeds to step S37, and if the determination is NO, the process proceeds to step S36. In step S36, the output of the received audio signal is stopped, and the process returns to step S22 of FIG. 4A. In step S37, it is determined whether or not a radio signal is received by the reception / demodulation unit 21, and if YES, the process proceeds to step S38, whereas if NO, the process returns to step S35. In step S38, the audio signal switching unit 23 switches to select the output of an audio signal from the reception / demodulation unit 21, and the process returns to step S25.

[0038] Fig. 5 is a timing chart showing an example of the operation of a wireless communication system including the wireless transmitting / receiving device of Fig. 1 and the wireless receiving device of Fig. 2. The wireless communication system is composed of a wireless transmitting / receiving device including modulation transmitting units 11 and 12 and a receiving / demodulating unit 13, and a wireless receiving device including receiving / demodulating units 21 and 22.

[0039] 5, before the transmission time (t1) of the modulation transmission unit 11, the reception / demodulation unit 13 performs carrier sense (CS) to confirm that channel 1 is free, and the modulation transmission unit 11 starts transmitting a radio signal on channel 1 at time t1. Next, at time t2, for example, 2 minutes and 55 seconds after the expiration of the 3-minute limit after the transmission of the modulation transmission unit 11, the modulation transmission unit 12 starts transmitting a radio signal on channel 2. However, carrier sense (CS) of channel 2 is performed before time t2. Then, at time t11, when the 3-minute limit has expired, the modulation transmission unit 11 stops the radio transmission.

[0040] Next, similarly, at time t3, for example, 2 minutes and 55 seconds after the expiration of the 3-minute limit after the wireless transmission of the modulation transmission unit 12, the modulation transmission unit 11 starts transmitting a wireless signal on channel 1. However, carrier sense (CS) for channel 1 is performed before time t3. Thereafter, at time t21, when the wireless transmission expires after 3 minutes, the modulation transmission unit 12 stops wireless transmission. Thereafter, the same operation can be repeated, thereby enabling the wireless transmission / reception device of FIG. 1 to continue transmitting the same series of audio signals.

[0041] In contrast, the radio receiving device is configured with receiving and demodulating units 21, 22 and an audio signal switching unit 23, and the radio receiving device can be, for example, a small radio receiver for a disaster prevention radio system, or the speaker 25 can be a large disaster prevention radio speaker for broadcasting.

[0042] 5, when the receiving and demodulating unit 21 receives a radio signal on channel 1 at time t1, the audio signal received on channel 1 is output from the speaker 25. Thereafter, when the receiving and demodulating unit 22 receives a radio signal on channel 2, the audio signal switching unit 23 switches to the audio signal received on channel 2 and outputs it from the speaker 25. Next, when the receiving and demodulating unit 21 receives a radio signal on channel 1 again, the audio signal switching unit 23 switches to the audio signal received on channel 1 and outputs it from the speaker 25. By repeating this operation, it is possible to continue receiving radio signals on two channels and output a series of audio signals from the speaker 25 without interruption.

[0043] As described above, the control unit 10 of the wireless transceiver device controls the modulation transmission unit 12 to start wireless transmission before the wireless transmission of the modulation transmission unit 11 ends. The control unit 10 also controls the modulation transmission unit 11 to start wireless transmission before the wireless transmission of the modulation transmission unit 12 ends. Furthermore, the control unit 20 of the wireless receiving device controls the audio signal switching unit 23 to switch to and output the audio signal from the reception demodulation unit 22 when the reception demodulation unit 22 receives wireless signals during wireless reception by the reception demodulation unit 21. Furthermore, the control unit 20 controls the audio signal switching unit 23 to switch to and output the audio signal from the reception demodulation unit 21 when the reception demodulation unit 21 receives wireless signals during wireless reception by the reception demodulation unit 22.

[0044] By combining the wireless transmitting / receiving device of Figure 1 described above with the wireless receiving device of Figure 2, the transmitting wireless transmitting / receiving device continues to transmit the same series of audio signals, and the receiving wireless receiving device receives either channel 1 or 2 in overlapping fashion, making it possible to transmit audio signals wirelessly without interruption regardless of a time limit of, for example, three minutes.

[0045] 5, at time t3, the modulation transmission unit 11 is performing wireless transmission on channel 1, but if no other wireless signals are received by carrier sense (CS), it may perform wireless transmission on another channel, for example, channel 3. Also, at time t4, the modulation transmission unit 12 is performing wireless transmission on channel 2, but if no other wireless signals are received by carrier sense (CS), it may perform wireless transmission on another channel, for example, channel 4.

[0046] (Modification of the first embodiment) A modification of the first embodiment is characterized in that the wireless transmitting / receiving device of Fig. 1 is applied to a broadcast transmission facility of a disaster prevention radio system, and the wireless receiving device of Fig. 2 is applied to a broadcast reception facility of the disaster prevention radio system. Here, the speaker 25 of Fig. 2 is configured as a large broadcast speaker.

[0047] In FIG. 1, the audio signal level measurement unit 18 compares the audio signal of the disaster prevention radio broadcast audio input from the audio signal input unit 16 with a predetermined threshold value to determine whether the audio signal has been input, and if the answer is YES, proceed to S6 in the case of step S4 in FIG. 3A, or proceed to S15 in the case of step S13 in FIG. 3B.

[0048] That is, outdoor disaster prevention speakers installed by local governments and the like broadcast emergency broadcasts during disasters, but residents often cannot hear the sound from the speakers and cannot understand the content because they have their windows closed or the sound of wind and rain makes it difficult to hear. The transmission start condition (step S4 in FIG. 3A, step S13 in FIG. 3B) of the wireless transceiver device of FIG. 1 according to the first embodiment is replaced by the PTT key 14p on the operation unit, and wireless transmission is initiated when an audio signal is input from the audio signal input unit 16 and an audio input exceeding a certain threshold level occurs. This allows wireless transmission to be initiated by the audio signal from the disaster prevention speaker, and audio from the speaker 25 of FIG. 2 to be transmitted uninterruptedly regardless of the three-minute time limit.

[0049] By using the wireless receiving device of Figure 2 to receive the wireless signal transmitted from the wireless transmitting / receiving device of Figure 1, it is possible to receive the sound from the disaster prevention speaker without interruption, regardless of whether the window is open or closed, or whether it is wind or rain, and regardless of the three-minute time limit.

[0050] (Embodiment 2) Figures 6A and 6B are flowcharts showing transmission and reception control processing executed by a wireless transmission / reception device for a wireless communication system according to embodiment 2. Figures 7A and 7B are flowcharts showing reception control processing executed by a wireless reception device according to embodiment 2. Here, the wireless communication system according to embodiment 2 has the same configuration as the wireless transmission / reception device in Figure 1 and the wireless reception device in Figure 2, but has the following operational differences.

[0051] (1) Step S1 in Fig. 3A is replaced with the processing of step S1A in Fig. 6A. In step S1A, the PTT 14p is awaited to be turned on (or, in a modified example, the input of an audio signal from the audio signal input unit 16 is awaited), the receiving and demodulating unit 13 is placed in a reception standby state on an arbitrary channel for carrier sense (CS), and the time values ​​of the 3-minute timers T1 and T2 are reset to 0 seconds. (2) The processing of step S10 in Fig. 6A is inserted between YES in step 7 in Fig. 3A and step S2. In step S10, the receiving and demodulating unit 13 switches the channel for wireless reception to a channel different from the channel on which the wireless signal was received in step S7. (3) Step S8 in Fig. 3A is replaced with step S8A in Fig. 6A. In step S8A, the modulation-transmission unit 11 starts wireless transmission on the same channel as the reception-demodulation unit 13, which did not receive a wireless signal in step S7. (4) The processing of step S19 in Fig. 6B is inserted between YES in step S16 in Fig. 3B and step S11. In step S19, the receiving and demodulating unit 13 switches the channel for wireless reception to a channel different from the channel through which the wireless signal was received in step S16. (5) Step S17 in Fig. 3B is replaced with step S17A in Fig. 6B. In step S17A, the modulation / transmission unit 12 starts wireless transmission on the same channel of the reception / demodulation unit 13 where no wireless signal was received in step S16.

[0052] (6) Step S21 in Fig. 4A is replaced with step S21A in Fig. 7A. In step S21A, the receiver / demodulator 21 waits for incoming radio reception, for example, on a predetermined arbitrary channel, and the receiver / demodulator 22 waits for incoming radio reception, for example, on a channel different from the predetermined arbitrary channel. (7) The processing of step S22A in Fig. 7A is inserted between NO in step S22 in Fig. 4A and step S22. In step S22A, if there is no signal in step S22, the receiving and demodulating unit 21 switches the channel and receives radio signals. (8) The processing of step S30A in Fig. 7A is inserted between NO in step S30 and step S28 in Fig. 4A. In step S30A, if there is no signal in step S30, the receiving and demodulating unit 22 switches channels and performs wireless reception. (9) The processing of step S37A in Fig. 7B is inserted between NO in step S37 and step S35 in Fig. 4B. In step S37A, if there is no signal in step S37, the receiving and demodulating unit 21 switches the channel and receives radio signals.

[0053] The problems to be solved in the second embodiment configured as above are as follows.

[0054] After the modulation transmission unit 11 of the wireless transceiver device of Figure 1 in embodiment 1 transmits wirelessly on channel 1, the modulation transmission unit 12 attempts to transmit wirelessly on channel 2 before the three-minute time limit expires. However, when carrier sense (CS) detects that channel 2 is in use, the carrier sense is activated, and the modulation transmission unit 12 does not transmit on channel 2, and the transmission of the same sound voice signal is interrupted.

[0055] Therefore, before the modulation transmission unit 12 starts transmission, the reception / demodulation unit 13 is used to scan unused channels, switch to a transmittable channel, and the modulation transmission unit 12 performs wireless transmission. And / or, before the modulation transmission unit 11 starts transmission, the reception / demodulation unit 13 is used to scan unused channels, switch to a transmittable channel, and the modulation transmission unit 11 performs wireless transmission. This makes it possible to prevent wireless transmission of the same audio signal from being interrupted due to carrier sense.

[0056] In the wireless receiving device according to the second embodiment, since the wireless signal is received from the wireless transmitting / receiving device according to the second embodiment, the receiving / demodulating unit 22 performs a channel scan, demodulates the audio signal received on the channel on which the audio signal is received, and outputs the demodulated audio signal. And / or the receiving / demodulating unit 21 performs a channel scan, demodulates the audio signal received on the channel on which the audio signal is received, and outputs the demodulated audio signal. This makes it possible to receive and output the audio signal of the transmitted wireless signal from the wireless transmitting / receiving device according to the second embodiment without interruption, regardless of the time limit of, for example, three minutes.

[0057] (Embodiment 3) Fig. 8 is a block diagram showing an example of the configuration of a wireless receiving device for a wireless communication system according to embodiment 3. In Fig. 8, the wireless transmitting / receiving device and the wireless receiving device according to embodiment 3 have the following differences compared to the wireless transmitting / receiving device in Fig. 1 and the wireless receiving device in Fig. 2. (1) The wireless transmitting / receiving device of FIG. 1 is used, but the modulation transmitting units 11 and 12 wirelessly transmit an end code when the time limit expires. (2) In FIG. 8, instead of the audio signal switching unit 23, an audio signal adding unit 23A and received audio signal muting units 31 and 32 are provided.

[0058] 8, an audio signal adding unit 23A adds the audio signals from the receiving and demodulating units 21 and 22 and outputs the audio signal resulting from the addition to an audio signal amplifying unit 24. The control unit 20 mutes (silences) the audio signal from the original receiving and demodulating unit 21 or 22 in response to an end code from the wireless transceiver at the reception start time (t2, t3, t4, t5 in FIG. 5) of the next receiving and demodulating unit 22 or 21. Here, the end code is an example of an end signal indicating the expiration of a time limit of, for example, three minutes for the audio signal, and is, for example, a predetermined pattern of a digital binary signal.

[0059] Figures 9A and 9B are flowcharts showing transmission and reception control processing of a wireless transmission / reception device used in a wireless communication system according to embodiment 3. Figures 10A and 10B are flowcharts showing reception control processing of the wireless reception device of Figure 8. Figures 9A to 10B differ from Figures 3A to 4B in the following points.

[0060] (1) The processing of step S3A in Fig. 9A is inserted between YES in step S2 and step S3 in Fig. 3A. In step 3A, the modulation transmission unit 11 transmits an end code at the end of, for example, a three-minute audio signal. (2) The processing of step S12A in Fig. 9B is inserted between YES in step S11 and step S12 in Fig. 3B. In step S12A, the modulation transmission unit 12 transmits an end code at the end of, for example, a three-minute audio signal.

[0061] (3) Step S23A in Fig. 10A is inserted in place of step S23 in Fig. 4A. In step S23A, the audio signal adding unit 23A outputs the audio signal from the receiving and demodulating unit 21. (4) The processing of steps S27A and S27B in Fig. 10A has been inserted between YES in step S27 and step S25 in Fig. 4A. In step S27A, the reception demodulation unit 21 determines whether or not an end code has been received in the demodulated signal. If YES, the processing proceeds to step S27B, whereas if NO, the processing returns to step S25. In step S27B, the reception audio signal mute unit 31 mutes the input audio signal and outputs it. (5) Step S31 in Fig. 4B is replaced with step S31A in Fig. 10B. In step S31A, the audio signal adding unit 23A outputs the audio signal from the receiving and demodulating unit 22. (6) The processing of steps S34A and S34B in Fig. 10B has been inserted between step S34 YES and step S32 in Fig. 4B. In step S34A, the reception demodulation unit 22 determines whether or not an end code has been received in the demodulated signal. If the result is YES, the processing proceeds to step S34B, whereas if the result is NO, the processing returns to step S32. In step S34B, the reception audio signal mute unit 32 mutes the input audio signal and outputs it. (7) Step S38A in Fig. 10B is inserted in place of step S38 in Fig. 4B. In step S38A, the audio signal adding unit 23A outputs the audio signal from the receiving and demodulating unit 21.

[0062] According to the third embodiment configured as described above, an end code is added at the end of transmission from the wireless transmitting / receiving device of Fig. 1, and the audio signal adding unit 23A of the wireless receiving device of Fig. 8 adds and outputs the audio signals from the receiving and demodulating units 21 and 22, while the received audio signal muting units 31 and 32 at the preceding stage mute the audio signals when they receive the end code. This makes it possible to transmit audio signals continuously without interruption for more than the three-minute time limit, just like in the first and second embodiments.

[0063] (Modification of the third embodiment) Instead of the mute according to the third embodiment, an AGC (automatic gain control) may be used to keep the level of the audio signal to be output almost constant.

[0064] Furthermore, the end code has been described as an example of an end signal indicating the expiration of a time limit of, for example, three minutes for an audio signal, but it may also be possible to compare the audio signal with a predetermined threshold value and determine that the audio signal has ended when a predetermined duration (for example, about five seconds) has continued, thereby stopping the output of the audio signal from the received wireless signal and further stopping the reception of the received wireless signal.

[0065] (Variation) The first, second and third embodiments and their modifications configured as described above may be configured in combination with one another.

[0066] The transmission time limit of 3 minutes and the 5 seconds (predetermined time) before the expiration of the transmission time limit for the second or subsequent wireless transmissions are merely example values ​​and can be changed based on design values ​​or laws and regulations, etc. [Industrial Applicability]

[0067] As described above in detail, the wireless communication device of the present invention can provide a wireless communication device that can be applied, for example, to a specific low-power wireless system, for example, to a disaster prevention wireless system, and a wireless communication system equipped with the wireless communication device. [Explanation of symbols]

[0068] 1~5 Antennas 10 Control Unit 11,12 Modulation transmitter 13 Reception demodulation section 14 Control section 14p PTT key 15 microphones 16 Audio signal input section 17 Audio signal amplifier 18 Audio signal level measurement section 19 Received radio signal level measurement section 21, 22 Reception demodulation section 23 Audio signal switching section 23A Audio signal addition section 24 Audio signal amplifier 25 speakers 31, 32 Received audio signal mute section T1, T2 3 minute timer

Claims

1. a first wireless receiving unit that wirelessly receives a wireless signal modulated in accordance with an audio signal on a first channel and demodulates the wireless signal into a first audio signal; a second wireless receiving unit that wirelessly receives, via a second channel, a wireless signal modulated in accordance with the audio signal and demodulates the wireless signal into a second audio signal; an audio output unit that selectively switches between and outputs the first audio signal and the second audio signal in conjunction with the start of wireless reception by the first and second wireless receiving units, or adds and outputs the first audio signal and the second audio signal; a first control unit that controls the first and second wireless receiving units, A wireless communication device, wherein the first control unit controls the audio output unit to switch to and output the second audio signal when the second wireless receiving unit receives a wireless signal while the first wireless receiving unit is receiving a wireless signal.

2. 2. The wireless communication device according to claim 1, wherein the first control unit controls the audio output unit to switch to and output the first audio signal when the first wireless receiving unit receives a wireless signal during wireless reception by the second wireless receiving unit.

3. The wireless communication device according to claim 1 , wherein the first control unit controls the first wireless receiving unit and the second wireless receiving unit to alternately perform wireless reception.

4. 4. The wireless communication device according to claim 3, wherein, when the first control unit controls the wireless reception of the first wireless receiving unit and the wireless reception of the second wireless receiving unit to be alternately repeated, after the wireless reception of the second wireless receiving unit, the first control unit controls the first wireless receiving unit to perform wireless reception on the first channel or a third channel.

5. A wireless communication device as described in any one of claims 1 to 4, wherein the first control unit controls at least one of the first and second wireless receiving units to search for a wireless signal modulated according to an audio signal while scanning channels, and to wirelessly receive the wireless signal on the searched channel.

6. A wireless communication device described in any one of claims 1 to 5, wherein the first control unit controls the first and second wireless receiving units to mute the audio signal output from the wireless receiving unit that received the end signal when the first and second wireless receiving units each receive an end signal.

7. a first wireless communication device that is a wireless communication device according to any one of claims 1 to 6; a second wireless communication device, the second wireless communication device, a first wireless transmission unit that transmits a wireless signal modulated in accordance with an audio signal over the first channel intermittently within a predetermined first time limit; a second wireless transmission unit that is a wireless transmission unit separate from the first wireless transmission unit, and that wirelessly transmits a wireless signal modulated in accordance with the audio signal over the second channel within a predetermined second time limit and intermittently; a second control unit that controls the first and second wireless transmission units, The second control unit controls the wireless transmission of the wireless signal modulated according to the audio signal by the first wireless transmitting unit and the wireless transmission of the wireless signal modulated according to the audio signal by the second wireless transmitting unit to be performed simultaneously for a predetermined time by starting the wireless transmission of the second wireless transmitting unit before the wireless transmission of the first wireless transmitting unit is terminated by the first time limit.

8. a first wireless communication device that is the wireless communication device according to claim 2; a second wireless communication device, the second wireless communication device, a first wireless transmission unit that transmits a wireless signal modulated in accordance with an audio signal over the first channel intermittently within a predetermined first time limit; a second wireless transmission unit that is a wireless transmission unit separate from the first wireless transmission unit, and that wirelessly transmits a wireless signal modulated in accordance with the audio signal over the second channel within a predetermined second time limit and intermittently; a second control unit that controls the first and second wireless transmission units, the second control unit starts wireless transmission of the second wireless transmission unit before the wireless transmission of the first wireless transmission unit is terminated by the first time limit, thereby controlling wireless transmission of the wireless signal modulated in accordance with the audio signal by the first wireless transmission unit and wireless transmission of the wireless signal modulated in accordance with the audio signal by the second wireless transmission unit to be performed simultaneously for a predetermined time; a second control unit that controls the wireless transmission of the first wireless transmission unit to start before the wireless transmission of the second wireless transmission unit ends due to the second time limit, so that the wireless transmission of the first wireless transmission unit and the wireless transmission of the second wireless transmission unit are performed simultaneously for a predetermined time.

9. 9. The wireless communication system according to claim 7, wherein the first time limit and the second time limit are the same or different from each other.

10. The wireless communication system according to any one of claims 7 to 9, wherein the second control unit controls the wireless transmission of the first wireless transmission unit and the wireless transmission of the second wireless transmission unit to be alternately repeated.

11. 11. The wireless communication system according to claim 10, wherein, when the second control unit controls the wireless transmission of the first wireless transmission unit and the wireless transmission of the second wireless transmission unit to be alternately repeated, the second control unit controls the first wireless transmission unit to wirelessly transmit on the first channel or a third channel after the wireless transmission of the second wireless transmission unit.

12. 12. The wireless communication system according to claim 7, wherein the second control unit starts transmission of the first wireless transmission unit in response to a transmission key being turned on.

13. the audio signal is an audio signal transmitted in a predetermined wireless system, The wireless communication system according to any one of claims 7 to 11, wherein the second control unit starts transmission of the first wireless transmission unit when the audio signal becomes equal to or greater than a predetermined threshold value.

14. a wireless receiving unit that performs carrier sensing while scanning channels to search for an unused channel before starting wireless transmission of at least one of the first and second wireless transmitting units; The wireless communication system according to any one of claims 7 to 13, wherein the second control unit controls the first and second wireless transmission units to transmit wirelessly using the searched unused channels.

15. A wireless communication system comprising the wireless communication device according to any one of claims 1 to 5, the first control unit controls, when the first and second wireless receiving units each receive an end signal, to mute an audio signal output from the wireless receiving unit that has received the end signal; The wireless communication system according to any one of claims 7 to 14, wherein the second control unit controls the first and second wireless transmission units to wirelessly transmit an end signal at the end of each wireless transmission.

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