Radio transceiver

Abstract: Disclosed is a booster apparatus wherein a detected signal which an input power detecting means outputs is subjected to a fixed processing and made to be a reference voltage for level-setting, and a transmitting level setting means controls the gain of an amplifier in such a manner that a detected signal which a transmitting power detecting means outputs and the reference voltage are balanced with each other.

Description: The invention relates to a radio transceiver for use with a booster apparatus, the booster apparatus amplifying a transmitting signal of the radio transceiver by 8dB when connected to the radio transceiver. Fig. 1 is a block diagram showing a conventional transceiver and a conventional booster apparatus. In Fig. 1, reference numeral la denotes a radio transceiver, in which 2 is an amplifier which amplifies a transmitting signal. Detector 3 detects an output signal of the amplifier 2 and an automatic power control comparator 4 (hereinafter called an APC comparator) controls the gain of amplifier 2. Voltage generator 5 provides a reference voltage to the APC comparator 4, and 6a is a control unit which produces an operational class signal and a selection signal representing a specified power level. Receiving unit 7 demodulates a received signal from a duplexer 8. Furthermore, duplexer 8 outputs the output signal of the amplifier 2 to an antenna connecting terminal 9, and at the same time, outputs a received signal inputted from the antenna connecting terminal 9 to the receiving unit 7. Control terminal 10 outputs a transmitting output control signal from control unit 6a to a Booster apparatus 12a, and 11 is a detection terminal for detecting the connection of the booster apparatus 12a. Booster apparatus 12a has a signal terminal 13 which is connected to the antenna connecting terminal 9 of the radio transceiver la. Signal input terminal 14 has inputted the transmitting output control signal from control terminal 10, and connecting terminal 15 is connected to the detection terminal 11. Connections are schematically illustrated by the dotted lines. Duplexer 16 outputs a transmitting signal received from signal terminal 13 to an amplifier 17 and also outputs a received signal to the signal terminal 13. Amplifier 17 amplifies the transmitting signal inputted from the duplexer 16, and detector 18 detects an output signal of the amplifier 17. APC comparator 19a controls the gain of the amplifier 17, and voltage generator 20 provides a reference voltage to the APC comparator 19a. Receiving amplifier 21 amplifies a received signal from duplexer 22 and outputs it to the duplexer 16. Duplexer 22 also supplies an output signal of the amplifier 17 to an antenna connecting terminal 23 for the booster apparatus, and also supplies a received signal inputted from the antenna connecting terminal 23 for the booster apparatus to the receiving amplifier 21. The operation of the prior art radio transceiver and booster apparatus will be described hereinafter. Communication iE performed by the radio transceiver alone when the booster apparatus 12a is not connected to it. In such case, a transmitting signal is amplified by the amplifier 2 and sent out via the duplexer 8 and the antenna connecting terminal 9 to an antenna (not shown). The detector 3 detects the output signal of the amplifier 2. For reception purposes, received signals received by the antenna are inputted through terminal 9 via the duplexer 8 to the receiving unit 7. The receiving unit 7 demodulates the received signal and outputs information on the transmitting output level to the control unit 6a. The received signal includes information on the transmitting output level (hereinafter called level information) which is sent out from a base station to indicate a transmitting output level for the radio transceiver. The control unit 6a outputs a selection signal corresponding to the received level information to the voltage generator 5. The voltage generator 5 generates a reference voltage corresponding to the selection signal and outputs it to the APC comparator 4. The APC comparator 4 controls the gain of the amplifier 2 in such a manner that the detected signal fed back from the detector 3 and the reference voltage output from the voltage generator 5 are equal. In this way, the control for setting the output level of the transceiver's transmission output signal consistent with the transmitting output level directed from the base station is accomplished. When the booster apparatus 12a is connected to the radio transceiver la, the antenna connecting terminal 9 is connected to the signal terminal 13 and the detection terminal 11 is connected to the connecting terminal 15. At the same time, the control terminal 10 is connected to the signal input terminal 14. These connections are illustrated by the dotted lines. The control unit 6a detects the connection of the connecting terminal 15 to the radio transceiver la. As a result, the connection of the booster apparatus to the radio transceiver alters the operational class of the transmitting output level. Since the connection of the booster apparatus 12a allows the transmitting output level to be raised, a change in the operational class occurs. A signal representing the transmitting output level is therefore produced and transmitted to the base station by a transmission unit not shown. The transmitting output level of the combination of the transceiver 1a and the booster apparatus 12a can then be controlled on the side of the booster apparatus 12a. Specifically, the voltage generator 5 generates the reference voltage, and the signal level of the output signal of the amplifier 2 becomes equal to an input level of the amplifier 17 on the side of the booster apparatus 12a. The reference voltage in this case is in accordance with the instruction of the control unit 6a and it is a fixed value when the booster apparatus 12a is connected. The control unit 6a thus outputs a fixed value selection signal in accordance with the level information from receiving unit 7 such that the voltage generator 5 generates a fixed reference voltage. Further, the level information is transmitted from control unit 6a via the control terminal 10 and the signal input terminal 14 to the voltage generator 20 on the side of the booster apparatus 12a. The voltage generator 20 on the side of the booster apparatus 12a thus generates a reference voltage "in accordance" with such level information as received from control unit 6a. The APC comparator 19a on the side of the booster apparatus 12a receives a reference voltage and the detected signal of the detector 18 to set gain of the amplifier 17. In this way, the transmitting signal which has a fixed signal level output from the radio transceiver la is boosted to become equal to a transmitting output level specified from the base station. The boosted signal is sent out via the duplexer 22 on the side of the booster apparatus 12a through the antenna connecting terminal 23 from an antenna (not shown). The received signal from the base station via connecting terminal 23 and duplexer 22 is inputted to the radio transceiver la after the attenuation inside the booster apparatus 12a is compensated by the receiving amplifier 21. Since the conventional booster apparatus and radio transceiver are constructed as described above, various problems have resulted. Specifically, cables between the radio transceiver la and the booster apparatus 12a and a plurality of control lines in the booster apparatus 12a and the radio transceiver la are needed in order to transfer the level information (control signal). Also, a circuit for controlling multi-stage transmitting levels is needed in the booster apparatus 12a. From US-A-4 574 248 an RF power amplifier, i. e. a booster amplifier, for use with a VHF transceiver is known, comprising a power amplifier which is controlled in its gain in such a way that the output power is in a certain proportion to the input power. The input power is measured by an input sensor and the output power is measured by an output sensor, and the output signals of these two sensors are compared by a differential amplifier, the output signal of which controls the gain of the power amplifier in such a way that the output follows proportionally the input power. It is an object of the present invention to provide a radio transceiver for use with a booster apparatus, in which the radio transceiver can be operated in connection with the booster apparatus, or also alone. The transceiver is to be simplified by eliminating a control signal path between the radio transceiver and the booster apparatus for controlling the output power of the booster amplifier. It is further an object of the present invention to provide a radio transceiver which, in combination with the booster apparatus, cannot transmit unpermissable output signals. In accordance with the invention, a radio transceiver for use with a booster apparatus is constructed as defined in the claim. Other details and advantages will be apparent from the detailed description of the following embodiments with reference to accompanying drawings. Fig. 1 is a block diagram showing a conventional booster apparatus and a radio transceiver; Fig. 2 is a block diagram showing a booster apparatus and a radio transceiver according to one embodiment of this invention; Fig. 3 is a circuit diagram showing a detailed configuration of the voltage generator, the APC comparator, and the detector of the embodiment of Fig. 2; Fig. 4 is a diagram showing one example of the relationship between level information and a transmitting output level; Fig. 5 and Fig. 7 are block diagrams showing booster apparatus and radio transceivers according to further embodiments of this invention; Figs. 6A-6B and 8A-8D are output diagrams showing one example of the relation between an output signal of a detector and a transmitting output level and the relation between an output signal of a logarithmic amplifier and an operational amplifier and a transmitting output level; Fig. 9 and Fig. 10 are block diagrams showing radio transceivers according to other embodiments of this invention; and Fig. 10a is a diagram showing the level deciding circuit in the booster apparatus. A preferred embodiment of this invention will be described with reference to drawings. In Fig. 2, reference numeral 6 is a control unit in radio transceiver 1 having a power level selecting means, 19 is an APC comparator provided in booster apparatus 12, and 24 is a detector provided on the input side of the amplifier 17. The other parts are identified by the same numerals as those in Fig. 1 and are the same as those shown in Fig. 1. In the embodiment of Fig. 2, it is not necessary to provide the control terminal 10, the signal input terminal 14, and the voltage generator 20 which are provided in the conventional system. As illustrated in figure 2, the signal received from the base station is inputted at antenna connecting terminal 23 and is received in transceiver 1 via receiving amplifier 21, duplexer 16, signal terminal 13 to antenna connecting terminal 9. The signal transmitted from amplifier 2 is inputted to booster 12 via the signal terminal 13 to duplexer 16 and to the detector 24. Fig. 3 is a circuit diagram showing a portion of the circuit of APC comparator 4 of the radio transceiver 1 and a portion of the circuit of APC comparator 19 of the booster apparatus 12 in detail. In Fig. 3, reference numeral 41 is an operational amplifier which is provided with a reference voltage supplied from the voltage generator 5 and a detected signal of the detector 3 to control gain of the amplifier 2, 42 is a feedback resistor, 43 is a transistor which amplifies an output signal of the operational amplifier 41. Selector 51 in voltage generator 5 connects one of resistors 52a - 52h in accordance with a selection signal 61 outputted from the control unit 6 and 53 is a voltage dividing resistor which produces a reference voltage by dividing the power source voltage together with the resistors 52a - 52h connected to the output side of the selector 51. Also, reference numeral 192 is an operational amplifier for controlling the gain of the amplifier 17. Adjusters 191 and 195 adjust, i.e amplify or reduce the signal level from detectors 24 and 18. One input signal of the operational amplifier 192 is obtained by level-adjusting using the second adjuster 195, the detected signal being obtained by detecting the signal level of the output signal of the amplifier 17 which is outputted from the detector 18. The other input signal of operational amplifier 192 is obtained using the adjuster 191 which adjusts a detected signal output from the detector 24 voltage. In the embodiment of Fig. 2, the detector 3 in the radio transceiver 1 operates as an output power detecting means, the APC comparator 4 and the voltage generator 5 operate as a second transmitting level setting means. In the booster apparatus 12, the detector 24 operates as an input power detecting means, detector 18 operates as a transmitting power detecting, and the APC comparator 19 operates as a transmitting level setting means. The operation of the apparatus embodied in Fig. 2 will be described hereinafter. In the case where the booster apparatus 12 is not connected to the radio transceiver, the radio transceiver 1 performs the communication operation the same as that in the conventional case (Fig. 1). In the case where the booster apparatus 12 is connected to the radio transceiver 1, the detection terminal 11 is connected to the connecting terminal 15, and the antenna connecting terminal 9 is connected to the signal terminal 13 as shown by the dotted lines in Fig. 2. The control unit 6 detects that the connecting terminal 15 is connected, and that the booster apparatus 12 is connected to the radio transceiver 1. The operational class of combination of the transceiver 1 and the booster 12 as a whole is altered in the same way as in the conventional case and as will be discussed with reference to Figure 4. The control unit 6 conducts the same control as that in the case where only the radio transceiver 1 performs communication. Specifically, level information included in the received signal is received via the booster apparatus 12 and the antenna connecting terminal 9. Then, the selection signal 61 corresponding to the level information is outputted to the voltage generator 5 as shown in Fig. 3. The selector 51 in the voltage generator 5 selects the resistors 52a - 52h corresponding to the level information in accordance with the selection signal 61. The resistance values need only be set which correspond to the transmitting output levels in operational class III as shown in Fig. 4. The selected resistors 52a - 52h and the voltage dividing resistor 53 produce a reference voltage, which is inputted to the operational amplifier 41 in the APC comparator 4. The operational amplifier 41 is also supplied with the detected signal of the detector 3. The output signal of amplifier 41 is amplified by the transistor 43 to control the power gain of the amplifier 2 and thus automatically adjusted until both input signals are balanced with each other. The transmitting signal which is supplied from the radio transceiver 1 to the booster apparatus 12 is provided with a transmitting output level corresponding to the level information received from the base station. As described above, the transmitting signal corresponding to the level information is inputted via the signal terminal 13 and the duplexer 16 to the detector 24 in the booster apparatus 12. The detector 24 generates a DC voltage corresponding to the signal level of the transmitting signal; in short, the detection 24 generates a detected signal and outputs it to the adjuster 191 of APC comparator as shown in Fig. 3. The amplifier 17 amplifies the input transmitting signal in such a manner that the transmitting output level of the transmitting signal becomes equal to a transmitting output level specified by the base station. Therefore, the signal level of the output signal of the amplifier 17 as a detected signal of the detector 18 is inputted to the APL comparator 19. Here, the detected signal from detector 18 is level-adjusted by the second adjuster 195. The adjuster 191 provides a fixed amplification or attenuation to the output signal of the detector 24 in such a manner that the signal produced by the operational amplifier 192 and the transistor 194 enables a fixed gain of the amplifier 17. The operational amplifier 192 controls the gain of the amplifier 17 in such a manner that the reference voltage produced by the adjuster 191 operating as described above and the detected signal of the detector 18 are balanced with each other. As described above, the transmitting output level of the output signal of the amplifier 17 is consistent with the value specified by the level information from the base station. Booster apparatus 12 therefore alters the transceiver's signal from a class III to a class I and provides a final boost of 8 dB in the output level. Fig. 4 shows one example of the relation between the class and the level information in a radio communication system. For instance, the level information "000" specifies the transmitting output level to be 6dBW in the class I, and -2dBW in the class III. In such a system, the resistance values of the resistors 52a - 52h in the voltage generator 5 need only to be set to values corresponding to the transmitting output levels in the class III, respectively. In the case where only the radio transceiver 1 performs communication, the communication based on the class III, six kinds of resistors 52a-52f are left to select. For instance, in the case where two pieces of level information "101" and "000" are received from the base station, the control unit 6 needs only output a selection signal which selects the resistor 52d and the resistor 52a, respectively. On the other hand, after the booster apparatus 12 is connected to the radio transceiver 1 and the class III is altered to the class I (unit 6 receives a connection signal from detection terminal 11), eight kinds of resistors 52a -52h are left to select. For instance, in the case where three signals of level information "000", "001" and "111" are received, the control unit 6 needs only to output a selection signal which selects the resistor 52a, the resistor 52b, and the resistor 52h. In other words, the control unit 6 is left to have a same level selection means which selects the resistors 52a -52h in the order of the transmitting output levels irrespective of the class. Such a constitution of the control unit 6 causes the signal level of the transmitting signal output from the antenna connecting terminal 9 of the radio transceiver 1 to be lower by 8dB than the value specified from the base station. Then, the input transmitting signal may be raised by 8dB in the amplifier 17 in the booster apparatus 12. In short, the adjuster 191 adjusts the detected signal of the detector 24 in such a manner that the amplifier 17 amplifies the input transmitting signal by 8dB. The present invention can also be modified to handle the case where the transmitting output level from the radio transceiver 1 is set lower, for example, as in the above case where it is set to -30dBW. At such low transmitting output level, the signals output from the detector 18 and 24 become distorted. As a result, there is a possibility that the signal level of the output signal of the amplifier 17 is out of the operating specification. The logarithmic amplifier 25 and 26, as shown in Figure 5, are added as an input power detecting means and a transmitting power detecting means between the detector 24 and the APC comparator 19 and between the detector 18 and the APC comparator 19 by which the detecting signals may be corrected. Examples of each of the detected signals of the detectors 18 and 24 and each of the output signals of the logarithmic amplifiers 25 and 26 are shown in Fig. 6A and Fig. 6B. In the case where the slope characteristics between the output signal of the detector 24 and that of the detector 18 are widely different from each other (For example, the case as shown in Fig. 8A), the logarithmic amplifiers 25 and 26 are provided to improve linearity. In addition, the operational amplifier 27 may be added as an input power detecting means between the logarithmic amplifier 25 and the APC comparator 19 as shown in Fig. 7. Thus, the output signal of the logarithmic amplifier 25 can be linearized. The output diagram as shown in Fig. 8B is corrected into the output diagram as shown in Fig. 8C by the logarithmic amplifiers 25 and 26, and further corrected into the output diagram as shown in Fig. 8D by the operational amplifier 27. Fig. 9 is a block diagram showing a radio transceiver according to another embodiment of this invention. In Fig. 9, reference numeral 28 is a level signal terminal which is provided in the booster apparatus 12 and supplied with a DC voltage output from the detector 18. Level input terminal 29 is provided in the radio transceiver 1 and supplied with the above-mentioned DC voltage from terminal 28. Element 30 represents a booster power source unit connected to a power supply terminal 31 and a power input terminal 32. Control unit 6a is added with a level deciding means as in the control unit 6 in each of the above-mentioned embodiments. Also, power source 30 for the booster apparatus 12 is supplied from the radio transceiver 1. Next, the operation will be described. In the case where the booster apparatus 12 is not connected to the radio transceiver, the radio transceiver 1 performs communication in the same way as in the conventional case and the above-mentioned embodiments. In the case where the booster apparatus 12 is connected to the radio transceiver 1, the level input terminal 29 and the level signal terminal 28 are connected with each other as illustrated by the dotted line, and the power supply connecting terminal 31 and the power input terminal 32 are similarly connected with each other. In this state, the operation for sending out the transmitting signal with the output level in accordance with the transmitting level specified from the base station is the same as the operations of the above-mentioned respective embodiments. Accordingly, the description will be omitted. However, according to a further aspect of the invention, the level deciding means of the control unit 6a monitors the transmitting output level of the booster apparatus 12 via the detector 18, the level signal terminal 28, and the level input terminal 29 even when the transmitting signal is not sent out. Since the control unit 6a controls the radio transceiver 1, it can instantly recognize whether the transmitting signal is sent out or not. In the case where the booster apparatus 12 has transmitted an output but without transmission, such as can result from oscillations and so forth in the amplifier 17, the control unit 6a can detect when a DC voltage which the detector 18 outputs has exceeded a predetermined level. In such a case, the control unit 6a outputs a logic level 1 to the power source 30 for the booster. Then, the power source 30 for the booster functions so as to cut off the power source (PS) from the power supply terminal 31. In a further embodiment of the present invention, the unlawful transmission of signals can be prevented by introducing the DC voltage output by detector 24 into and the level deciding circuit 33 as shown in Fig. 10 for comparing the DC voltage with a predetermined level. Fig. 10A further illustrates the arrangement of level deciding circuit in booster apparatus 12. In this case, when the DC voltage level of the detector 24 is not less than the level of the minimum transmitting signal level which is input to the booster apparatus 12, the level deciding circuit 33 functions so as to supply power to the amplifier 17. While the reference voltage of the comparator 34 shown in Fig. 10 is rendered a level of the minimum transmitting signal, the power source (PS) needs only to be switched by the transistor 35 in order to cut off power to amplifier 17. Therefore, when the signal level falls below the minimum transmitting signal level, power is cut off to amplifier 17 As described above, the power source applied to the amplifier 17 is controlled, allowing transmission of unlawful signals to be prevented. The above-mentioned respective embodiments (those shown in Fig. 9 and Fig. 10) can be, of course, added with the logarithmic amplifiers 25 and 26 and the operational amplifier 27 shown in Fig. 5 or Fig. 7. As mentioned above, since the booster apparatus and the radio transceiver are constructed in such a manner that the transmitting output level in accordance with the level information is always controlled by the radio transceiver, and the transmitting signal is amplified with a fixed gain in the booster apparatus, control signals between the main body of the radio transceiver and the booster apparatus can be eliminated, thus simplifying construction. In addition, if the booster apparatus is constructed to include the level deciding circuit, the transmission of unlawful signals can be prevented.

Claims: A radio transceiver (1) for use with a booster apparatus having a gain of 8dB, comprising: an amplifier (2) which amplifies a transmitting signal generated in the transceiver; an output power detecting means (3) which detects the signal level of an output signal of said amplifier (2); an antenna connecting terminal (9) coupled to the output of said amplifier (2), and to which, in a first operational class, an input terminal (13) of the booster apparatus (12) or, in a second operational class, an antenna is connected; a receiving unit (7) coupled to said antenna connecting terminal (9) and which demodulates a received signal input to provide level information indicating one of 8 steps of power levels of 4dB, except for the two highest levels in the second operational class; a detection terminal (11) adapted to be connected to a connecting terminal of said booster apparatus, to provide a connection signal when said booster apparatus is connected to said transceiver (1); a control unit (6; 6a) which receives said level information from said receiving unit (7) and derives a selection signal (61) from said level information, the correspondence of values of the table between said selection signal values and said level information values being changed between the first operational class and the second operational class in response to said connecting signal in view of the gain of the booster apparatus; a voltage generator (5) comprising a voltage divider consisting of a plurality of first resistors (52a - 52h) corresponding to the number of levels of said level information in the first operational class and a second resistor (53), as well as a selector (51) which selects one of the first resistors (52a - 52h) in accordance with said selection signal value to generate a reference voltage in accordance with the selected first resistor from a fixed voltage, wherein, in the first operational class all first resistors (52a - 52h) are selectable, in the second operational class all but the first resistors (52g, 52h) belonging to the two lowest levels are selectable; and an APC comparator (4) receiving said reference voltage and an output signal from said power detecting means (3) to set the gain of said amplifier (2) in such a way that the output of said amplifier (2) corresponds to said selection signal value (61).

Inventors: FURUNO KENICHI, FURUNO, KENICHI, FURUNO, KENICHI MITSUBISHI DENKI KK COMMUNICATIONS
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1990
Main classification: H04B1
IPC codes: H04B7, H04B1