Abstract:
A plurality of detectors each output a detection signal corresponding to an output power of a corresponding one of a plurality of transmitting units. The detection signal passes through a corresponding one of a plurality of rectifiers each corresponding to the associated detector and is inputted to an input terminal of a smoothing device to allow the detection signal to be smoothed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-065255, filed Mar. 8, 2001, the entire contents of which are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a transmission apparatus, such as a radio telephone apparatus, and a transmission power detecting apparatus for detecting transmission power at such the transmission apparatus.  
           [0004]    2. Description of the Related Art  
           [0005]    [0005]FIG. 1 shows an arrangement of a radio transmitting section of a conventional radio telephone apparatus.  
           [0006]    The radio telephone apparatus has a transmitting unit  1  and transmitting unit  2 . The transmission frequency of the transmitting unit  1  is a predetermined frequency fl. The transmission frequency of the transmitting unit  2  is a predetermined frequency f 2  higher than the frequency fl. The transmitting units  1  and  2  comprise modulators  1   a  and  2   a , intermediate frequency band oscillators  1   b  and  2   b , AGC amplifiers  1   c  and  2   c , up-converters  1   d  and  2   d , local oscillators  1   e  and  2   e , bandpass filters  1   f  and  2   f , and power amplifiers  1   g  and  2   g , respectively.  
           [0007]    The transmitting units  1  and  2  have their transmit operations controlled by a controller  3  to prevent both from simultaneously outputting their transmit signals. The transmit signals which are outputted from the transmitting units  1  and  2  are supplied, respectively through bandpass filters  4  and  5 , to a diplexer  6  and then to an antenna  7  where each transmit signal is radiated.  
           [0008]    In this type of radio telephone apparatus, it is necessary to monitor transmission power so as to, for example, control it. To this end, a transmission power detecting apparatus  8  is provided. The transmission power detecting apparatus  8  has power detectors (DET)  8   a  and  8   b , a rectifying diode  8   c  and smoothing capacitor  8   d.    
           [0009]    The power detectors  8   a  and  8   b  detect the power levels of outputting signals from the transmitting units  1  and  2 . The power detectors  8   a  and  8   b  output detection signals representing the detecting power levels. Thus, the detection signal becomes an AC signal having its level varied in accordance with a variation in power level of the outputting signals from the transmitting units  1  and  2 .  
           [0010]    The output terminals of the power detectors  8   a  and  8   b  are connected to the anode of the rectifying diode  8   c . An output terminal T is connected to the cathode of the rectifying diode  8   c , and the cathode of the rectifying diode  8   c  is grounded through the smoothing capacitor  8   d . Thus, the detection signal outputted from either of the power detectors  8   a  and  8   b  is converted to a DC voltage by the rectifying diode  8   c  and smoothing capacitor  8   d  and outputted from the output terminal T.  
           [0011]    In such transmission power detecting apparatus  8 , the transmitting units  1  and  2  perform no simultaneous transmit operation and, by utilizing this, a DC voltage conversion circuit is shared, the DC voltage conversion circuit comprising the rectifying diode  8   c  and smoothing capacitor  8   d . By doing so, the circuit size is made smaller.  
           [0012]    Incidentally, if the transmission power detecting apparatus  8  is so configured as set out above, a portion of the output signal of one of the transmitting units flows into the other transmitting system, thus producing a waste loss. As a result, the transmission power becomes smaller.  
           [0013]    Further, there is sometimes the case where, depending upon a relation between the frequencies fl and f 2 , a high harmonic wave of one frequency occupies the same frequency band of the other frequency. In this case, there is a risk that the high harmonic wave flows into said other transmitting system will be supplied through the bandpass filter  4  or bandpass filter  5  to the antenna  7  and a high harmonic component will be radiated.  
         BRIEF SUMMARY OF THE INVENTION  
         [0014]    The object of the present invention is to provide an apparatus which has a simple structure and can yet prevent transmitting systems from flowing unnecessary signals from one the other.  
           [0015]    According to one aspect of the present invention, there is provided a transmission power detecting apparatus used for a transmission apparatus having a plurality of transmitting units with each transmission unit performing no simultaneous transmit operation relative to a remaining transmitting unit and adapted to detect a transmission power at the output of the transmission unit, comprising a plurality of detectors each configured to output a detection signal corresponding to an output power of a corresponding one of the transmitting units; a plurality of rectifiers each configured to receive an output of the corresponding detector at an input terminal and to allow a flow of only electric current from the input terminal toward an output terminal; and a smoothing device configured to smooth a signal supplied to one input terminal to which output terminals of the rectifiers are connected.  
           [0016]    According to another aspect of the present invention, there is provided a transmission apparatus comprising a plurality of transmitting units each configured to perform no simultaneous transmit operation relative to a remaining transmitting unit; a plurality of detectors each configured to output a detection signal corresponding to an output power of the corresponding one of the transmitting units; a plurality of rectifiers each configured to receive an output of the corresponding detector at an input terminal and to allow only electric current from the input terminal toward an output terminal; a smoothing device configured to smooth a signal supplied one input terminal to which the output terminals of the rectifiers are connected; and a controller configured to control transmission power of the transmitting unit, which is performing the transmit operation, on the basis of a signal smoothed by the smoothing device.  
           [0017]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0018]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present invention.  
         [0019]    [0019]FIG. 1 is a view showing an arrangement of a radio transmission section of a conventional radio telephone apparatus;  
         [0020]    [0020]FIG. 2 is a view showing an arrangement of a radio transmitting section of a radio telephone apparatus according to an embodiment of the present invention; and  
         [0021]    [0021]FIG. 3 is a timing chart showing the timing of transmit operations of two transmitting units shown in FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    One embodiment of the present invention will be described below by referring to the accompanying drawings.  
         [0023]    [0023]FIG. 2 is a view showing an arrangement of a radio transmitting section of a radio telephone apparatus according to the present embodiment. The same reference numerals are employed in the embodiment to designate parts or elements corresponding to those in FIG. 1.  
         [0024]    The radio transmitting section of the radio telephone apparatus shown in FIG. 2 has transmitting units  1  and  2 , bandpass filters  4  and  5 , diplexer  6 , antenna  7 , transmission power detecting apparatus  9  and controller  10 .  
         [0025]    The transmitting unit  1  comprises a modulator  1   a , an intermediate frequency band oscillator  1   b , an AGC amplifier  1   c , an up converter id, a local oscillator  1   e , a bandpass filter  1   f  and a power amplifier  1   g . The transmitting unit  2  comprises a modulator  2   a , an intermediate frequency band oscillator  2   b , an AGC amplifier  2   c , an up converter  2   d , a local oscillator  2   e , a bandpass filter  2   f , and a power amplifier  2   g.    
         [0026]    A transmit signal of a baseband applied from a baseband section, not shown, is used as a modulating signal and, with it, intermediate frequency band signals applied from intermediate frequency band oscillators  1   b  and  2   b  are modulated by modulators  1   a  and  1   b  to provide transmit signals of an intermediate frequency band. The transmit signals outputted from the modulators  1   a  and  1   b  are amplified by the AGC amplifiers  1 C and  2 C, respectively. The transmit signals thus amplified are mixed, by the up converters  1   d  and  2   d , with local signals of frequencies fl and f 2 , respectively, supplied from the local oscillators  1   e  and  2   e . By doing so, these signals are up-converted to radio frequency bands having the frequencies fl and f 2  as center frequencies, respectively. The transmit signals outputted from the up-converters  1   d  and  2   d  have their undesired frequency components eliminated by the bandpass filters if and  2   f , respectively. The transmit signals coming from the bandpass filters  1   f  and  2   f  are amplified, by the power amplifiers  1   g  and  2   g , up to power levels necessary to their radio transmission. The outputs of the power amplifiers  1   g  and  2   g  are used respectively as the outputs of the transmitting units  1  and  2 , respectively.  
         [0027]    The bandpass filters  4  and  5  eliminate undesired power contained in the transmit signals outputted from the transmitting units  1  and  2 , respectively.  
         [0028]    The diplexer  6  supplies the transmit signals outputted from the bandpass filters  4  and  5 , respectively, to the antenna  7 . The antenna  7  radiates the transmit signal supplied from the diplexer  6 .  
         [0029]    The transmission power detecting apparatus  9  comprises power detectors (DET)  8   a  and  8   b , smoothing capacitor  8   d  and diodes  9   a  and  9   b.    
         [0030]    The transmit signals outputted from the transmitting units  1  and  2  are inputted to the power detectors  8   a  and  8   b , respectively. The power detectors  8   a  and  8   b  detect the power levels of the inputted transmit signals and output detection signals of those levels corresponding to these power levels, respectively. Thus the detection signals become an AC signal of a varying level corresponding to a variation in power level of output signals from the transmitting units  1  and  2 .  
         [0031]    The detection signal outputted from the power detector  8   a  is supplied to the anode of the diode  9   a . The detection signal outputted from the power detector  8   b  is supplied to the anode of the diode  9   b . The cathodes of the diodes  9   a  and  9   b  are commonly connected to an output terminal T.  
         [0032]    The smoothing capacitor  8   d  is connected at one end to the cathodes of the diodes  9   a  and  9   b  and at the other end to ground.  
         [0033]    The controller  10  controls the operations of the transmitting units  1  and  2 . The controller  10  controls the transmit operation of the transmitting units  1  and  2  in an ON/OFF fashion so as to prevent both the transmitting units  1  and  2  from simultaneously outputting the transmit signals as shown, for example in FIG. 3. Further, the controller  10  controls the gains of the AGC amplifiers  1   c  and  2   c  so as to adjust the transmit output from the transmitting units  1  and  2  to a predetermined level on the basis of an output from the output terminal T.  
         [0034]    The operation of the radio telephone apparatus thus configured will be explained below. The operation involving the transmission of the transmit signals is the same as that of the existing equivalent apparatus and its operation is, therefore, omitted. Here, an explanation will be made below about the operation associated with the transmission power detection by the transmission power detecting apparatus  9 .  
         [0035]    Under the control of the controller  10 , the transmitting units  1  and  2  perform the transmit operations in mutually different timings.  
         [0036]    Assume that the transmitting unit  1  performs a transmit operation. Then a transmit signal is outputted from the transmitting unit  1  and it is supplied through the bandpass filter  4  and diplexer  6  to the antenna  7  where it is radiated. The transmit signal outputted from the transmitting unit  1  is inputted to the power detector  8   a  in the transmission power detecting apparatus  9 . At this time, the transmitting unit  2  performs no transmit operation and there is no inputting of a transmit signal to the power detector  8   b  in the transmission power detecting apparatus  9 .  
         [0037]    In this state, the detection signal outputted from the power detector  8   a  is rectified by the diode  9   a  and smoothed by the smoothing capacitor  8   d . As a result, the level of the detection signal outputted from the power detector  8   a  appears on the output terminal T. That is, a DC voltage of a level corresponding to the power level of the transmit signal outputted from the transmitting unit  1  emerges on the output terminal T. As this time, a signal passed through the diode  9   a  is blocked by the diode  9   b  and it is not flowed into the power detector  8   b . That is, the transmit signal outputted from the transmitting unit  1  is blocked by the diode  9   b  from being flowed into a transmitting system on the transmitting unit  2  side.  
         [0038]    If, on the other hand, the transmitting unit  2  performs a transmit operation. Then a transmit signal is outputted from the transmitting unit  2  and it is supplied through the bandpass filter  5  and diplexer  6  to the antenna  7  where it is radiated. The transmit signal outputted from the transmitting unit  2  is inputted to the power detector  8   b  in the transmission power detecting apparatus  9 . At this time, the transmitting unit  1  performs no transmit operation and there is no inputting of the transmit signal to the power detector  8   a  in the transmission power detecting apparatus  9 .  
         [0039]    In this state, the detection signal outputted from the power detector  8   b  is rectified by the diode  9   b  and smoothed by the soothing capacitor  8   d . As a result, the level of the detection signal outputted from the power detector  8   b  appears on the output terminal T. That is, a DC voltage of a level corresponding to the power level of the transmit signal outputted from the transmitting unit  2  emerges on the output terminal T. At this time, a signal passing through the diode  9   b  is blocked by the diode  9   a  and it is not flowed into the power detector  8   a . That is, the transmit signal outputted from the transmitting unit  2  is blocked by the diode  9   a  from being flowed into a transmitting system on the transmitting unit  1  side.  
         [0040]    According to the present embodiment, therefore, a transmit signal on one transmitting system is not flowed into the other transmitting system through the transmission power detecting apparatus  9 , thus positively preventing a waste loss from being produced. Further, the high harmonic wave of a transmit signal on one transmitting system is prevented from being flowed into the other transmitting system. By doing so, an undesired wave, such as a high harmonic wave, is positively prevented from being released.  
         [0041]    In the present embodiment, a single diode is operated both for rectification and for blocking, so that it is possible to realize a very simple structure.  
         [0042]    The present invention is not restricted to the above-mentioned embodiment. Even if three or more transmitting units are employed, it is possible to readily apply the present invention to that structure by providing a diode corresponding to an individual transmitting unit. It is not necessary to employ mutually different transmission frequencies for respective transmitting units and the present embodiment may also include a plurality of transmitting units having the same transmission frequency.  
         [0043]    The transmission power detecting apparatus of the present invention can also be applied to any other kind of radio transmission apparatus or wired transmission apparatus, etc.  
         [0044]    As a rectifier, use may also be made of other kinds of elements or circuits so long as they perform an electrical function similar to the diodes  9   a  and  9   b.    
         [0045]    As a smoothing means, use may also be made of other kinds of elements and circuits so long as they perform an electrical function similar to the smoothing capacitor  8   d.    
         [0046]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.