Abstract:
At least two or more wireless communication apparatuses ( 10 ) of the present invention are located adjacently or separately in a relatively confined area, wherein the output portion ( 4 ) of any one of currently used wireless communication apparatus of the wireless communication apparatuses ( 10 ) is connected to each input portions ( 3 ) of the other standby wireless communication apparatuses ( 10 ), while a radio signal being transmitted from the transmitter ( 2 ) of the currently used wireless communication apparatus ( 10 ), a reception limit signal is transmitted from the output portion ( 4 ) of said currently used apparatus to the respective input portions of the nearby standby apparatuses ( 10 ) so that the reception ability of the receiver ( 1 ) of said standby apparatus ( 10 ) is effectively limited.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention relates to a wireless communication apparatus, a wireless communication system employing a plurality of such wireless communication apparatuses that is employed in a wireless communication system wherein other wireless communication apparatuses are used as standby apparatuses during the operation of any one of currently used wireless communication apparatus of those apparatuses, and a method for controlling a plurality of the same apparatuses. 
       BACKGROUND OF THE INVENTION 
       [0002]    As a precaution against malfunctions, boats and ships or the like which use wireless communication apparatuses are equipped, for example, with two wireless communication apparatuses, both are turned on, one predetermined unit of which is used as the main wireless communication apparatus, and the other is held in reserve as a standby unit. 
         [0003]    Under these circumstances, the signals transmitted from the one main wireless communication apparatus are received by the other spare wireless communication apparatuses i.e. the other standby apparatuses. 
         [0004]    A technique for switching between the currently used apparatus (this is called a current apparatus) and the standby apparatus during the use of such wireless communication apparatuses has been disclosed, for example, in the following patent document 1. 
         [0005]    Patent Document 1: Laid open Japanese Patent Publication (unexamined) No. 296719/1989 
         [0006]    When two wireless communication apparatuses, for example, are provided in a limited space such as in boats and ships or the like, the antennas for the two wireless communication apparatuses must be set up adjacent to each other. In such cases, the signal strength from the main wireless communication apparatus will be too strong for the other adjacent standby wireless communication apparatus, and the receiver of the standby wireless communication apparatus may therefore become damaged. Even if the receiver is not damaged, there have been problems in that the radio signals from the main wireless communication apparatus act as interference on the adjacent standby wireless communication apparatus. 
         [0007]    Furthermore, even when a main wireless communication apparatus, i.e. a current wireless communication apparatus and at least one more standby wireless communication apparatuses are operated on unequal frequencies separately from each other, there have been problems in that a noise or voice sound is put out from the speaker of the standby apparatus due to spurious signals included in the signals transmitted from the main wireless communication apparatus. 
         [0008]    However, no technique for eliminating the problems described above has been disclosed in the above-mentioned Patent Document 1 or the like, and in actuality users must resort to manually turning off the standby wireless communication apparatus, lowering the volume of the standby wireless communication apparatus, or the like, which is inconvenient. 
       SUMMARY OF THE INVENTION 
       [0009]    An object of the present invention, which was designed to overcome the various drawbacks noted above, is to provide a wireless communication apparatus, as well as a wireless communication apparatus system, wherein a signal transmitted from a certain main wireless communication apparatus does not produce problems in other wireless communication apparatuses, even when a plurality of wireless communication apparatuses is set up relatively closely apart, and the antennas for the wireless communication apparatuses are therefore set up in adjacent locations. 
         [0010]    The wireless communication apparatus according to a first aspect of the invention is basically composed of a receiver for receiving a radio signal from outside, a transmitter for transmitting a radio signal outside, an input portion to which a reception limit signal is input from outside, an output portion from which a reception limit signal is transmitted outside, a reception controller for limiting the reception ability of said receiver while a reception limit signal has been input to the input portion; and a limit signal controller for sending out the reception limit signal to said output portion while said transmitter is transmitting a signal therefrom. 
         [0011]    In another aspect of a wireless communication apparatus according to the invention, while a reception limit signal being input into the input portion, the power supply to the receiver is stopped by said reception controller, whereas while no reception limit signals being input into the input portion, the power supply to the receiver is controlled by the reception controller. 
         [0012]    In yet another aspect of a wireless communication apparatus according to the invention, a signal attenuator is connected to the signal input component of the receiver, wherein while a reception control signal being input to the reception controller, the signal attenuator is activated, whereby a received signal is attenuated, whereas while no reception control signals being input to the input portion, the signal attenuator is not activated, whereby a received signal is transferred to the receiver without being attenuated. 
         [0013]    Still another aspect of a wireless communication system according to the invention, the wireless communication system having at least two or more wireless communication apparatuses each of which comprises a receiver for receiving a radio signal, a transmitter for transmitting a radio signal, an input portion to which a reception limit signal is input, an output portion for putting out of a reception limit signal outside, a reception controller for limiting the reception ability of said receiver while said input portion is receiving a reception limit signal from outside, and a limit signal controller for sending out a reception limit signal to said output portion while said transmitter is transmitting a signal therefrom, wherein 
         [0014]    the out put portion of any one of those wireless communication apparatuses is connected to each input portions of the other wireless communication apparatuses, and while a signal being transmitted from said any one of the other wireless communication apparatuses, the limit signal controller of said any one of the others is to output a reception limit signal into each input portion of said other wireless communication apparatuses, whereby the respective reception ability of each receiver of the other wireless communication apparatuses is limited. 
         [0015]    Further another aspect of a method for controlling a plurality of wireless communication apparatuses according to the invention, each of which comprises a receiver for receiving a radio signal, a transmitter for transmitting a radio signal, an input portion to which a reception limit signal is input, an output portion for putting out of a reception limit signal outside, a reception controller for limiting the reception ability of said receiver while a reception limit signal being input into said input portion and a limit signal controller for sending out a reception limit signal to said output portion while said transmitter is transmitting a signal therefrom, in which the out put portion of any one of those wireless communication apparatuses is connected to each input portions of the other wireless communication apparatuses, 
         [0016]    wherein while a signal being transmitted from said any one of the wireless communication apparatuses, the limit signal controller of said any one of the wireless communication apparatuses is to output a reception limit signal to each input portion of said other wireless communication apparatuses, whereby the respective reception ability of each receiver of the other wireless communication apparatuses is limited. 
         [0017]    According to the wireless communication apparatus of the invention, the reception ability of the receiver is limited via the input portion when a reception limit signal is input from another wireless communication apparatus, and a radio signal transmitted from another nearby wireless communication apparatus such as a standby wireless communication apparatus is prevented from being received at too great of an intensity. The receivers can thereby be effectively protected. 
         [0018]    According to another wireless communication apparatus of the invention, the power supply to the receiver is stopped when a reception limit signal is input from another wireless communication apparatus to the input portion, thereby making it possible to securely prevent a radio signal transmitted from another wireless communication apparatus from being received at too great of an intensity. 
         [0019]    According to yet another wireless communication apparatus of the invention, when a reception limit signal is input from another wireless communication apparatus to the input portion, the signal attenuation means is activated to attenuate the receiver output level of the radio signal that is input to the receiver, allowing the minimum receiver function to be maintained. 
         [0020]    According to a wireless communication system of the present invention in which at least two wireless communication apparatuses are used, and the out put portion of any one of those wireless communication apparatuses is connected to each input portions of the other wireless communication apparatuses, in cases where the plurality of wireless communication apparatuses are located in a relatively confined area, when a radio signal is transmitted from the transmitter of the currently used main wireless communication apparatus, a reception limit signal is transmitted from the output portion of the currently used wireless communication apparatus to the input portion of the nearby standby wireless communication apparatus, the reception ability of each receiver of the respective standby wireless communication apparatuses is limited, and unwanted noise is effectively prevented from being produced from the receiver of the respective standby wireless communication apparatuses on the basis of radio signal transmitted from the currently used wireless communication apparatus. 
         [0021]    In addition, when a radio signal is transmitted from the currently used wireless communication apparatus, the signal attenuation means connected to the receiver of the standby wireless communication apparatus located near the main wireless communication apparatus is activated by the reception controller of the standby wireless communication apparatus to effectively attenuate the level of the radio signal input to the receiver from the main wireless communication apparatus, thereby effectively preventing unwanted noise or the like from being produced from the receiver of the stand wireless communication apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a block diagram of a first embodiment of the wireless communication apparatus of the invention; 
           [0023]      FIG. 2  is a block diagram of a wireless communication system composed of two wireless communication apparatuses of the invention; 
           [0024]      FIG. 3  is a time chart showing the operation of the wireless communication system of  FIG. 2 ; and 
           [0025]      FIG. 4  is a block diagram of a second embodiment of the wireless communication apparatus of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]    A detailed description will be provided in accordance with figures illustrating the radio communication device according to a preferred embodiment of the invention. 
         [0027]    The wireless communication apparatus related to the invention involves the use of at least two or more wireless communication apparatuses  10  connected by a dedicated line. As a dedicated line, for example, a shielded insulating wire or cable is available. 
         [0028]    As illustrated in  FIG. 1 , the wireless communication apparatus  10  is composed of a receiver  1 , transmitter  2 , an input portion  3  for receiving limit signals described in detail below ( FIG. 3 ) from the outside via the dedicated line, an output portion  4  for transmitting reception limit signals to the outside via the dedicated line, a CPU (central processing unit)  5  for comprehensively controlling the components, a transmitter regulator  6  for supplying power to the transmitter  2 , a receiver regulator  7  for supplying power to the receiver  1 , and a microphone  9  with a PTT (Push To Talk) switch  8 . 
         [0029]    When the user presses the PTT switch  8  while the receiver  1  is operating in a wireless communication apparatus  10  having the above structure, the operating state of the PTT switch  8  is detected by the CPU 5 , and the CPU 5  continues the output of the reception limit signals from the output portion  4 , limits, as described in detail below, the reception ability of the other standby wireless communication apparatus connected by the dedicated line to the relevant wireless communication apparatus, that is, the currently used main wireless communication apparatus  10 , and starts the transmission of radio signals from the transmitter  2  of the currently used wireless communication apparatus  10 . 
         [0030]    Further, the wireless communication apparatus  10  equipped with a common antenna  11  used in common for the receiver  1  and transmitter  2 , speaker  13  connected with the receiver  1  and any other necessary components (not shown), display, controls, power unit and on the like. 
         [0031]    The release of the push-on the PTT switch  8  is detected by the CPU 5 . The CPU 5  stops the output of the reception limit signal to the output portion  4 , and, stops the transmission of radio signals from the transmitter  2 , as described below. 
         [0032]    The transmitter regulator  6  also supplies and stops power to the transmitter  2  in response to control signals from the CPU 5 . The other receiver regulator  7  supplies and stops power to the receiver  1  in response to control command signals from the CPU 5 . 
         [0033]    When the input of reception limit signals to the input portion  3  is detected, the CPU 5  acts as a receiver controller for limiting the reception ability of the receiver  1 , and when radio signal transmission from the transmitter  2  is detected, acts as a limit signal controller so that reception limit signals are transmitted from the output portion  4  to the outside. 
       EXAMPLE 1 
       [0034]    Described below are examples in which a plurality of wireless communication apparatuses according to the invention are set up so as to be adjacent to each other a short distance apart, and are connected together by a dedicated wire and used, such as when arranged, for example, in the same boat or the same building. In this case, these wireless communication apparatuses can be located separately at a distance or adjacently. 
         [0035]    In the following description, M refers to a main currently used wireless communication apparatus which is any one of the located apparatuses, and the other standby wireless communication apparatuses are referred to as sub apparatuses S. 
         [0036]      FIG. 2  illustrates a wireless communication system composed of a main wireless communication apparatus M for transmission and a sub apparatus S as a standby apparatus connected by a dedicated line L. 
         [0037]    In the main wireless communication apparatus M of  FIG. 2 , the letter M is attached to the numbers used for components which are the equivalent of the structural components of the wireless communication apparatus  10  in  FIG. 1 . Similarly, the letter S is attached to the numbers used for components which are the equivalent of the structural components of the wireless communication apparatus  10 . These structural components will not be further elaborated. 
         [0038]    The main wireless communication apparatus M is composed of a receiver M 1 , a transmitter M 2 , an input portion M 3 , an output portion M 4 , CPU M 5 , a transmitter regulator M 6 , and receiver regulator M 7 . That main wireless communication apparatus M is briefly called a “main apparatus M” here after. A microphone M 9  having a PTT switch M 8  is also connected. Other necessary components include an antenna M 11  shared by the receiver M 1  and transmitter M 2 , a speaker M 13  connected to the receiver M 1 , and other parts which are not shown, such as a display, operating components, and power components. 
         [0039]    The sub apparatus S is composed of a receiver S 1 , a transmitter S 2 , an input portion S 3 , an output portion S 4 , CPU S 5 , a transmitter regulator S 6 , and a receiver regulator S 7 . A microphone S 9  having a PTT switch S 8  is also connected. That sub apparatus M is briefly called a “sub apparatus S” here after. Other necessary components include an antenna S 11  shared by the receiver S 1  and transmitter S 2 , a speaker S 13  connected to the receiver S 1 , and other parts which are not shown, such as a display, operating components, and power components. 
         [0040]    Described next will be the operation of the wireless communication system composed of the two wireless communication apparatuses above as illustrated in  FIG. 2 , along with a timing chart shown in  FIG. 3 . 
         [0041]    First, when the PTT switch M 8  of the microphone M 9  connected to the main apparatus M is pushed at the time T 1 , the CPU M 5  of the main apparatus M starts to observe whether the PTT switch M 8  is depressed continuously throughout a predetermined period of time. When it is detected at the time T 2  that the PTT switch M 8  has been depressed continuously all that while, the transmitter regulator M 6  is controlled to commence supplying power to the transmitter M 2  and results in rendering the transmitter M 2  operational. 
         [0042]    Simultaneously, when the CPU M 5  determines that the transmitter M 2  has been subjected to a radio signal transmission state, it begins to send out a reception limit signal from the output portion M 4  outside. 
         [0043]    When the transmitter M 2  being powered owing to the received reception limit signal, it is activated. The activated transmitter M 2  is stabilized at the time T 3  after a certain period of time, and then the transmitter M 2  begins to transmit radio-frequency signals such as, for example, audio-frequency signals transferred from the microphone M 9  via the antenna M 11 . 
         [0044]    On the other hand, when the sub apparatus S receives the reception limit signal put out from the main apparatus M via the dedicated line L on the input portion S 3 , the reception limit signal is transferred to the CPU S 5  of the sub apparatus S. When the CPU S 5  detects the reception limit signal, the receiver regulator S 7  is controlled to stop the supply of power to the receiver S 1 , thereby the reception operation of the receiver S 1  being stopped. 
         [0045]    In this way, the start of power supply to the transmitter M 2  of the main apparatus M, and the end of power supply to the receiver S 1  of the sub apparatus S occur substantially simultaneously. 
         [0046]    As noted above, because the transmitting of radio frequency signals from the main apparatus M starts at the time T 3  after a certain period of time following the start of power supply to the transmitter M 2  at the time T 2 , no power is supplied to the receiver S 1  of the sub apparatus S when the main apparatus M starts transmitting of radio frequency signals at the time T 3 , and the receiver S 1  therefore ceases its operation. As a result, the receiver S 1  of the sub apparatus S will not be damaged by signals transmitted from the main apparatus M, and output of voice sounds from the speaker S 13  of the sub apparatus S will be prevented. 
         [0047]    The transmitted waves will be prevented from becoming unstable because the transmission starts after the transmitter M 2  has become stable for a certain period of time following the start of power supply to the transmitter M 2  of the main apparatus M at the time T 2 . 
         [0048]    When the PTT switch M 8  of the microphone M 9  connected to the main apparatus M is released, the transmission of the main apparatus M is stopped. 
         [0049]    The CPU M 5  monitors whether or not the PTT switch M 8  has been continuously released for a certain period of time. When the CPU  5  realizes that the PTT switch M 8  has been continuously released all that while at the time T 5 , the transmitter regulator M 6  is controlled to stop the supply of power to the transmitter M 2 . At virtually the same time, the output of reception limit signals that are output from the main apparatus M is stopped. 
         [0050]    Because the output of reception limit signals from the main apparatus M is no longer detected in the sub apparatus S parallel with the above operations, power is again supplied to the receiver S 1  at the time T 5  to resume the reception operation. At that time, the transmission of signals from the main apparatus M has already stopped. 
         [0051]    Reception is started after the receiver S 1  has become stable for a certain period of time upon the resumption of power to the receiver S 1  of the sub apparatus S, thereby the reception operation being prevented from becoming unstable. 
         [0052]    When the PTT switch M 8  of the microphone M 9  connected to the main apparatus M is pushed at the time T 1  as illustrated above, the reception operation of the receiver S 1  of the sub apparatus S is stopped at the time T 2  before the transmitter M 2  of the main apparatus M actually begins transmitting of signals, thereby preventing the receiver S 1  of the sub apparatus S from becoming damaged by some overly strong reception of signals transmitted from the adjacent main apparatus M. Interference of signals are also eliminated well. 
         [0053]    On the other hand, providing that the PTT switch M 8  of the microphone M 9  connected to the main apparatus M is released at the time T 4  before returning on the power thereto, accordingly, the transmitter M 2  of the main apparatus M being kept turning on the power as well as the receiver S 1  of the sub apparatus S, by contraries, being kept turning off the power until the time T 5  at which the transmitter M 2  and the receiver S 1  are switched in reverse respectively, the transmitter M 2  of the main apparatus M remains in inoperative, that is, the transmitter M 2  stops transmitting of radio signals therefrom. Accordingly, the activated receiver S 1  of the sub apparatus S will be avoidable to be subjected to damage by any excessive strong signals arisen accidentally in the main apparatus M. 
         [0054]    In the first embodiment of the present invention, though the activated transmitter M 2  of the main apparatus M outputs the radio signals from the time T 3  until the time T 4 , the receiver S 1  of the sub apparatus S is stopped receiving of radio signals from the time T 2  until the time T 5  so that the receiver S 1  of the sub apparatus S is kept from damage caused by signals transmitted from the main apparatus M. 
         [0055]    After the end of transmission from the main apparatus M, the receiver S 1  of the sub apparatus S usually resumes the reception operation as a standby wireless communication apparatus. 
         [0056]    Alternatively, as illustrated in  FIG. 3 , the receiver M 1  of the main apparatus M may be constrained in a state of mute from the time T 2  until the time T 5  in which the transmitter  2  of the main apparatus M is powered so that it will be able to save quite a bit of electric power. 
         [0057]    Besides, when the sub apparatus S is used for transmission, the sub apparatus S is operated in the same manner as the main apparatus M described above, and the main apparatus M is operated in the same manner as the sub apparatus S described above. 
         [0058]    Further, the set of wireless communication apparatuses is not necessarily limited to only two wireless communication apparatuses. When three or more such communication apparatuses are used, any one transmitting wireless communication apparatus may be used as the main apparatus in the same manner as above, and the other wireless communication apparatuses may be used as the sub apparatuses. 
       EXAMPLE 2 
       [0059]    The above description was of an example in which the power supply to the receiver  1  was stopped when reception limit signals are input from the outside, but, as signal attenuation means, for example, a high frequency attenuator  12  can be connected between the receiver  1  and receiving antenna  11 , such as in the wireless communication apparatus  10 B shown in  FIG. 4 . When a reception limit signal is input from the outside, in order to avoid damage to the receiver  1  and prevent transmitting inhibitory signals outside, the signal attenuation means  12  can be controlled by the CPU  5  to attenuate the signal incoming through the receiving antenna  11  to the receiver  1 . 
         [0060]    When, on the other hand, no reception limit signals are input from the outside, the signal attenuation means  12  is controlled by the CPU  5  so that the signals input from the receiving antenna  11  to the receiver  1  are not attenuated and are input to the receiver  1 . 
         [0061]    According to the present invention, when reception limit signals are input, the signals input to the receiver  1  are attenuated by the signal attenuation means  12  (see  FIG. 4 ). Alternatively, the power supply to the receiver  1  is stopped (see  FIG. 1 ). The receiver  1  is thereby protected, even when the waves transmitted from the main apparatus M are strong. 
         [0062]    Also, when reception limit signals are input, the output of the receiver  1  may be rendered in mute. This will prevent inhibitory signals from being put out from the speaker of the sub apparatus S even when transmitted waves are output from the main apparatus M.