Abstract:
A radio apparatus ( 1 ), in particular for mobile radio, of a first predetermined power stage is proposed, whose broadcasting power can be increased by connecting a HF amplifier circuit. The radio apparatus ( 1 ) has an antenna output ( 5 ), to which an input ( 10 ) of a HF amplifier circuit ( 15 ) can be connected, for operating the radio apparatus ( 1 ) at a higher, second power stage. As a function of the HF amplifier circuit ( 15 ) connected to the radio apparatus ( 1 ), a transmitter unit ( 20 ) of the radio apparatus ( 1 ) outputs signals for transmission to a radio network, which signals contain the information about operation at the applicable power stage.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a radio apparatus. 
     PRIOR ART 
     The invention is based on a radio apparatus as generically defined by the preamble to the main claim. 
     From the publication entitled “European Digital Cellular Telecommunications System (Phase 2); Radio Transmission and Reception (GSM 05.05)” of the European Telecommunications Standard Institute (ETSI) of May 1994, specifications for mobile radio transmission and reception are known. A plurality of power stages are provided, such as a power stage  2  with a maximum output power of 8 W and a power stage  4  with a maximum power of 2 W. The power requirements made of the mobile radio apparatuses pertain to the antenna output of the applicable mobile radio apparatus. 
     From U.S. Pat. No. 5,303,395, a system for controlling the power stage of high-frequency (HF) signals that are output by a portable radio apparatus is known. The portable radio apparatus includes a first power supply, a first amplifier stage, and a microcomputer that is connected to the first amplifier stage in order to select from a plurality of power stages. An indicator signals when the radio apparatus is connected to a motor vehicle power supply. In response, the microcomputer generates a control signal, which is representative for the desired power stage. A second amplifier stage is connected to the first amplifier stage and receives HF signals that are at the first power stage. An amplifier control circuit is connected to the second amplifier stage and receives the control signal. It responds by setting the gain of the second amplifier stage to one of at least two constant gain values, so that the HF signals output at the desired power stages are made available. 
     From European Patent Disclosure EP 0 602 608 A1 a mobile radio apparatus is known that comprises a portable unit and a stationary part and that is provided for control between two apparatuses, each with its own control unit. By way of the control unit, a transmission power regulation is performed in the booster, and the booster is turned on and off from the portable apparatus. In the opposite direction, the portable apparatus receives information as to the presence or absence of a booster. The control signals needed in the booster are limited to two, namely the signal for switching over the amplification and the signal for turning all the power consumers on and off, except for the circuit that has to assure the control function between the booster and the hand-held apparatus in the standby mode. 
     ADVANTAGES OF THE INVENTION 
     The radio apparatus of the invention has the advantage over the prior art that the radio apparatus can be operated at various power stages and can thus be used flexibly. A further advantage is that an inexpensive radio apparatus with a lower power stage can easily be equipped for operation at a higher power stage by means of a connectable HF amplifier circuit. Thus using the appropriate accessory equipment, a single radio apparatus can be used for various power stages, making for an overall cost saving since only the applicable HF amplifier circuit has to be produced or purchased as an accessory, and not a complete new radio apparatus. 
     It is also advantageous that the range of a radio apparatus. 
     By means of the provisions recited in the dependent claims, advantageous refinements of and improvements to the radio apparatus defined by the main claim are possible. 
     It is especially advantageous to use an evaluation circuit and to detect a HF amplifier circuit connected to the radio apparatus by means of the evaluation circuit. This provides a simple opportunity of ascertaining the current power stage of the radio apparatus. 
     It is also advantageous that the radio apparatus has an input to which one output of the HF amplifier circuit can be connected; that the evaluation circuit is connected to the input; and that the evaluation circuit triggers the transmitter unit of the radio apparatus as a function of signals or the voltage drop at the input. In this way, a HF amplifier circuit connected to the radio apparatus can be detected especially simply and reliably, and the radio apparatus can be logged in in a simple way in accordance with its current power stage in the radio network. It is especially advantageous that the evaluation circuit is connected to the antenna output, and if the evaluation circuit triggers the transmitter unit of the radio apparatus as a function of signals or of the voltage drop at the antenna output. This affords an especially simple and reliable opportunity of detecting the connection of a corresponding HF amplifier circuit to the radio apparatus and to have the radio apparatus logged in in accordance with its current power stage in the radio network; no additional connecting line between the radio apparatus and the HF amplifier circuit is needed for detecting the connection of the HF amplifier circuit to the radio apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention are shown in the drawing and described in further detail in the ensuing. 
     FIG. 1 shows a block circuit diagram of a radio apparatus of the invention with a HF amplifier circuit connected to it, in a first embodiment; 
     FIG. 2, a block circuit diagram of a radio apparatus of the invention with a HF amplifier circuit connected to it in a second embodiment; and 
     FIG. 3, a flow chart for an evaluation circuit of a radio apparatus of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, reference numeral  1  designates a radio apparatus, embodied as a mobile telephone, with a transmission unit  20  that also includes a reception unit and will therefore hereinafter be called a transceiver unit  20 , and with an evaluation circuit  25  that is connected to the transceiver unit.  20 . The transceiver unit  20  is connected to an antenna output  5  of the mobile phone  1 , and the evaluation circuit  25  is connected to one input  30  of the mobile phone  1 . The mobile phone  1  also has a first resistor  40 , by way of which the input  30  is connected to a reference potential  45 . A HF amplifier circuit  15 , which has an input  10  connected to the antenna output  5 , is connected to the mobile phone  1 . An output  35  of the HF amplifier circuit  15 , connected to the input  30 , is likewise connected to the reference potential  45 , via a second resistor  55  of the HF amplifier circuit  15 . On the one hand, in a first switch position  80 , the input  10  can be connected via a switch  75  to the input of an amplifier  65 , whose output is connected to a transmission/reception antenna  70 ; on the other hand, in a second switch position  85 , the input  10  can be connected directly to the transmission/reception antenna  70 . Also connected to the input  10  is a detector circuit  60 , which triggers the switch  75 . 
     The mobile phone is operated, for instance in accordance with the publication “European Digital Cellular Telecommunications System (Phase 2); Radio Transmission and Reception (GSM 05.05)” of the European Telecommunications Standard Institute (ETSI) of May 1994, at a power stage  4  with a maximum output power of 2 W. By means of the HF amplifier circuit  15 , however, as a function of the gain of the amplifier  65 , operation of the mobile phone  1  at a higher power stage, such as the power stage  3  with a maximum output power of 5 W or the power stage  2  with a maximum output power of 8 W is possible. However, that requires that the mobile phone  1  from the outset meet the specifications of the aforementioned GSM standard 05.05 that are provided for the higher power stages. For instance, the mobile phone  1  has the higher intermodulation strength of −43 dBm, which are prescribed for the power stage  2 , instead of −49 dBm for the power stage  4 , and a higher sensitivity of −104 dBm, instead of −102 dBm, in the reception part of the transceiver unit  20 . 
     In FIG. 3, a flow chart for the operation of the evaluation circuit  25  is provided. Before a telephone call is made, the mobile phone  1  must report its power stage to a base station in the mobile radio network, so that the delay times required for synchronous data transmission can be established in accordance with the range of the mobile phone  1 , which is dependent on its power stage. Thus before a connection is made, the evaluation circuit  25  at program point  100  makes an inquiry about the voltage drop at the input  30 . If the voltage drop at the input is not maximal, then a jump to program point  110  is made, and otherwise a jump is made to program point  130 . At program point  110 , from the measured voltage drop, the power stage of the mobile phone  1 , supplemented with the HF amplifier circuit  15 , is ascertained. The second resistor  55  is set as a function of the gain of the amplifier  65 , so that from the power stage of the mobile phone  1  and the voltage drop at the input  30 , the evaluation circuit  25  can ascertain the power stage of the mobile phone  1  expanded by the HF amplifier circuit  15 . At program point  120 , the transceiver unit  20 , by means of a suitable control signal of the evaluation circuit  25 , is activated to output signals to the transmission/reception antenna  70  for transmission to a base station of the radio network, which signals contain information about operation at the ascertained power stage. The evaluation circuit  25  thus triggers the transceiver unit  20  of the mobile phone  1  as a function of the voltage drop at the antenna output  5 . Next, a departure from the program is made, and a switch connection can be made. A transmission signal transmitted from the antenna output  5  to the HF amplifier circuit  15  is detected by the detector circuit  60 , which then sets the first switch position  80  of the switch  75  for connection of the amplifier  65  and thus for transmission at the higher power stage. For reception, or in other words if the detector circuit  60  does not detect a transmission signal, the detector circuit switches the switch  75  over to the second switch position  85 , so that the transmission/reception antenna  70 , for receiving signals from the radio network, is connected directly to the antenna output  5  of the mobile phone  1 . At program point  130 , the transceiver unit  20  of the mobile phone  1  is activated by a suitable control signal of the evaluation circuit  25  for outputting signals, which contain information about operation at the power stage  4  of the mobile phone  1 , for transmission by the transmission/reception antenna  70  to a base station of the radio network. A departure is then made from the program, and a speech connection can be made. 
     In a further exemplary embodiment, shown in FIG. 2, identical elements are identified by the same reference numerals. In a distinction from the otherwise identically embodied exemplary embodiment of FIG. 1, in the exemplary embodiment of FIG. 2, the evaluation circuit  25  is again connected to the antenna output  5 , and the antenna output  5  here is connected to the reference potential  45  via a third resistor  50 . As indicated in dashed lines in FIG. 2, the input  10  in the HF amplifier circuit  15  can be connected to the reference potential  45  via a fourth resistor  90 . In that case, one input of the mobile phone  1  is not provided, and one output of the HF amplifier circuit  15  is also not provided. The voltage drop for detecting a connected HF amplifier circuit is ascertained by the evaluation circuit  25  thus directly at the antenna output  5 . The fourth resistor  90 , shown in dashed lines, of the HF amplifier circuit  15  is not absolutely necessary, since the input resistance of the HF amplifier circuit  15  can be used as a measure for the gain of the amplifier  65  and thus for the power stage attained together with the mobile phone  1 . 
     The first resistor  40  shown in FIG.  1  and the third resistor  50  shown in FIG. 2 can also be disposed inside the evaluation circuit  25  or can be formed by the appropriate internal resistance of the evaluation circuit  25  and in the exemplary embodiments described serves to illustrate the principle of detecting a connected HF amplifier circuit  15 . 
     By means of the amplifier  65  of the HF amplifier circuit  15 , the signal to be broadcast from the transmission/reception antenna  70  is amplified to the appropriate power in accordance with the higher, second power stage, while the signal to be received is sent on without impairment by the transmission/reception antenna  70  to the transceiver unit  20 . In the exemplary embodiment of FIG. 2, it may be necessary to take precautions in order to keep a transmission or reception signal free of interference caused by the detection of the connected HF amplifier circuit  15 , or to eliminate such interference. 
     The voltage source for generating the voltage drop at the input  30  in FIG. 1 or at the antenna output  5  in FIG. 2, which voltage drop is necessary for detecting a connected HF amplifier circuit  15 , can be accommodated by way of example in the evaluation circuit  25 , or in another way known to one skilled in the art can be connected to the input  30  or the antenna output  5  and is not shown in FIG.  1  and FIG. 2, respectively. 
     The radio apparatus of the invention may also be integrated with a car radio, for instance, and can be prepared for the connection of a HF amplifier circuit in accordance with the exemplary embodiments described above.