JPH0758662A - Radio transmitter receiver - Google Patents

Abstract

PURPOSE:To perform highly sensitive reception at the time of both simplex operation and duplex operation systems by respectively appropriately controlling a reception part, a transmission part, a switching means and a selecting means at the time of communication by a duplex operation and transmission by a simplex operation. CONSTITUTION:In the case of performing the communication of the duplex operation, an oscillation modulation circuit 16 and a power amplifier 17 are controlled so as to be in an operating state and transmission output is lead through a high frequency switching circuit 7 to a BPF 6. Further, a high frequency amplifier 3 and a mixer circuit 4 are controlled so as to be in the operating state and intermediate frequency signals are lead from an intermediate frequency switch 10 to an intermediate frequency amplifier 11. Thus, the transmission of a frequency fb is performed and the reception of the frequency fa is performed. In the case of performing the communication of the simplex operation, the amplifier 3 and the circuit 4 are in a non-operation state, the high frequency amplifier 8 and the mixer circuit 9 are in the non-operation state while the transmission is instructed, the power amplifier 17 and the oscillation modulation circuit 16 are controlled so as to be in the operating state and the transmission by the frequency fb is outputted through an antenna 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transceiver capable of selecting a duplex system capable of simultaneously transmitting and receiving at different frequencies and a simplex system capable of transmitting or receiving at the same frequency by switching between transmission and reception. .

[0002]

2. Description of the Related Art A conventional radio transmitter / receiver of this type is constructed, for example, as shown in FIG.
In order to perform communication by b, the high frequency switch circuits 21 and 23 are switched to the band pass filter 25 side having the frequency fb as the pass band under the control of the switch control circuit 24, and the frequency fb is passed through the band pass filter 25. The received signal is guided to the high frequency amplifier 26 for reception, and the high frequency switch circuit 21 is turned off and the high frequency switch circuit 22 is turned on under the control of the switch control circuit 24 at the time of transmission to generate an oscillation modulator. 27 and the power amplifier 28 are operated to perform transmission at the frequency fb.

During duplex, the high frequency switch circuit 22 is turned on to turn on the oscillation modulator 27 and the power amplifier 28.
Is operated to transmit at the frequency fb. Under the control of the switch control circuit 24, the high frequency switch circuits 21 and 25 are switched to the side of the band pass filter 29 having the frequency fa as the pass band, and the band pass filter 29.
The received signal having the frequency fa is guided to the high frequency amplifier 26 via the.

[0004]

However, when duplex communication is performed in the above-described conventional wireless transceiver, if the isolation of the high frequency switch circuit is poor, the leakage of the output power of the transmitter will pass the frequency fb. There is a problem in that it is added to the high frequency amplifier through a band pass filter that serves as a band. Further, if there is a large amount of leakage and this level is high, the high frequency amplifier and the mixer cause sensitivity suppression, which causes a problem that the reception sensitivity at the frequency fa is greatly reduced. Therefore, to receive with high sensitivity,
The high frequency switch circuit needs to be a circuit with good isolation, but there is a problem that the high frequency switch circuit with good isolation becomes large and expensive.

It is an object of the present invention to provide a radio transmitter / receiver which is small in size and inexpensive in price, and which enables highly sensitive reception in both the simplex system and the duplex system.

[0006]

SUMMARY OF THE INVENTION A radio transceiver according to the present invention is a radio transceiver capable of switching between duplex communication and simplex communication, and first and second central frequencies connected to an antenna are different. Bandpass filter of
A first receiving unit that amplifies the output from the first bandpass filter and converts it to an intermediate frequency, a switching unit connected to the second bandpass filter, and a received signal from the second bandpass filter. A second receiving unit that receives via the switching unit, amplifies, and converts to an intermediate frequency; a transmitting unit that transmits and transmits the transmission output of the center frequency of the second bandpass filter through the switching unit; In the case of communication by duplication with a selection unit that selects one of the outputs from the second receiving unit, the first receiving unit is in the operating state, the second receiving unit is in the non-operating state, and the transmitting unit is in the operating state. The switching means is controlled to guide the output of the transmitting section to the second bandpass filter and the selecting means is controlled to select the output of the first receiving section. 2 receiver is inactive , Controlling the transmitting unit to the operating state and the switching means to a state in which the output of the transmitting unit is guided to the second bandpass filter, and when receiving by simplex, the first receiving unit and the transmitting unit are deactivated, Control for controlling the second receiving section to the operating state, the switching means to the state of guiding the output of the second bandpass filter to the second receiving section, and the selecting means to the state of selecting the output of the second receiving section. Means and are provided.

In the radio transmitter / receiver of the present invention, the control means controls the transmission output from the transmission section to the second bandpass filter and the output of the second bandpass filter to the second bandpass filter. A second diode switch circuit for guiding to the receiver, a third diode switch circuit for selecting the output of the first receiver, a fourth diode switch circuit for selecting the output of the second receiver, and a duplex The first transistor switch means for controlling the first diode switch circuit to be in the ON state at the time of the communication by the communication and the simplex transmission, and the third transistor switch means for supplying the power to the transmission unit, and the third transistor switch means for the communication by the duplex communication. Second transistor switch means for turning on the diode switch circuit and supplying power to the first receiving portion, and second and second transistors for simplex reception. Third supplying power to the second receiver to control the diode switch circuit ON state
And transistor switching means.

[0008]

In the radio transmitter / receiver of the present invention, the received signal of the first center frequency input from the antenna is received by the first receiving section via the first band pass filter during the communication by the duplex. The output from the one receiving unit is selected by the selecting means. On the other hand, the transmission output of the transmission unit having the first center frequency is transmitted from the antenna via the second bandpass filter. In this case, the transmission output is greatly attenuated by the first bandpass filter, and the first reception unit has almost no sensitivity suppression at the first center frequency. Further, in this case, even if the isolation in the selection means is poor, the second receiving section is in a non-operating state, so that these become large attenuators and the leakage of the transmission output at the second center frequency is extremely small. . For this reason, the amplifier and the like connected to the first receiving section and the selecting means are not affected by leakage, and high-sensitivity reception is possible.

[0009]

EXAMPLES The present invention will be described below with reference to examples. Figure 1
FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention.

A bandpass filter 2 having an RF signal of frequency fa as a passband is connected to the antenna 1,
RF of frequency fa converted to an electric signal by the antenna 1
The signal is guided through the bandpass filter 2 to the high frequency amplifier 3 for amplification, and the amplified output of the high frequency amplifier 3 is guided to the mixer circuit 4 and output from the local oscillator 5 at a frequency (fa-
It is mixed with the oscillation output of fi) and converted to an intermediate frequency of frequency fi. The frequency-converted intermediate frequency signal from the mixer circuit 4 is guided to the intermediate frequency amplifier 11 via the intermediate frequency switch circuit 10 to be amplified, and the intermediate frequency amplified output is demodulator 1
2 is demodulated and output.

A bandpass filter 6 having a signal of frequency fb as a pass band is connected to the antenna 1, and the RF signal of frequency fb converted into an electric signal by the antenna 1 is transmitted to the bandpass filter 6 and The high frequency amplifier 8 is guided through the high frequency switch circuit 7 to be amplified, and the amplified output of the high frequency amplifier 8 is guided to the mixer circuit 9 and mixed with the oscillation output of the frequency (fb-fi) output from the local oscillator 5 to obtain the frequency fi. Convert to intermediate frequency. The frequency-converted intermediate frequency signal from the mixer circuit 9 is guided to the intermediate frequency amplifier 11 via the intermediate frequency switch circuit 10 to be amplified, and the intermediate frequency amplified output is demodulated by the demodulator 12 and output. is there.

On the other hand, a signal from the microphone 15 or the like is guided to the oscillation modulation circuit 16, the oscillation output of the frequency fb is modulated by the signal, and the modulated output is supplied to the power amplifier 17 for amplification, and the power amplifier 17 performs power amplification. The generated transmission output is passed through the high-frequency switch circuit 7 to the bandpass filter 6
It is configured so that it can be transmitted through the antenna 1.

Here, during duplexing, the switch control circuit 13
Under the control of 1), the high frequency amplifier 3 and the mixer circuit 4 are controlled to be in an operating state, and the intermediate frequency switch circuit 10 is controlled to guide the intermediate frequency signal frequency-converted by the mixer circuit 4 to the intermediate frequency amplifier 11. And high frequency amplifier 8
And the mixer circuit 9 is controlled to a non-operating state. During duplexing, under the control of the switch control circuit 14, the oscillation modulation circuit 16 and the power amplifier 17 are controlled to the operating state,
In addition, the high frequency switch circuit 7 is controlled so that the transmission output from the power amplifier 17 is guided to the bandpass filter 6.

On the other hand, during the simplex, under the control of the switch control circuit 13, the high frequency amplifier 3 and the mixer circuit 4 are controlled to the non-operating state. Further, during transmission in the case of simplex, the oscillation modulation circuit 16 and the power amplifier 17 are controlled to the operating state under the control of the switch control circuit 14, and the transmission output from the power amplifier 17 is controlled by the bandpass filter 6.
The high-frequency switch circuit 7 is controlled so as to lead to, and the high-frequency amplifier 8 and the mixer circuit 9 are controlled to be inactive under the control of the switch control circuit 13.

Furthermore, during reception in the case of simplex, under the control of the switch control circuit 14, the oscillation modulation circuit 16 and the power amplifier 17 are controlled in a non-operating state, and the control of the switch control circuit 13 is also controlled. In addition, the high frequency switch circuit 7 is controlled so that the output of the band pass filter 6 is guided to the high frequency amplifier 8, and the high frequency amplifier 8 and the mixer circuit 9 are controlled.
Is controlled to an operating state, and the intermediate frequency switch circuit 10 is controlled so that the intermediate frequency signal whose frequency is converted by the mixer circuit 9 is guided to the intermediate frequency amplifier 11.

As shown in FIG. 2, the high frequency switch circuit 7 is composed of a diode switch circuit having diodes D1 and D2 as switching elements, and during transmission, a high potential signal is applied as a control signal to the terminal A and the diode D1 is applied. Is controlled to an on state, the transmission output is guided to the bandpass filter 6, and during reception of the signal of the frequency fb, a high potential signal is applied as a control signal to the terminal B to control the diode D2 to be an on state to control the bandpass filter 6 To the high frequency amplifier 8.

As shown in FIG. 3, the intermediate frequency switch circuit 10 comprises a diode switch circuit having diodes D3 and D4 as switching elements, and applies a high potential signal as a control signal to the terminal C to turn on the diode D3. State, the intermediate frequency signal output from the mixer circuit 4 is guided to the intermediate frequency amplifier 11, and a high potential signal is applied as a control signal to the terminal D to control the diode D4 in the ON state and output from the mixer circuit 9. The generated intermediate frequency signal is guided to the intermediate frequency amplifier 11.

The switch control circuit 14 selectively selects the voltage from the power supply circuit as shown in FIG.
A transistor Q1 for applying a transmission output from the power amplifier 17 to the bandpass filter 6 by applying it to the terminal A of the power amplifier 17 and applying it to the oscillation modulation circuit 16 and the power amplifier 17 to activate the oscillation modulation circuit 16 and the power amplifier 17. A voltage output from the microcomputer 18 for controlling the wireless transceiver, which is configured by a switching circuit having the following, is applied to the base of the transistor Q1 during the duplex instruction and the transmission instruction in the case of simplex, thereby turning on the transistor Q1. The oscillation modulation circuit 16 and the power amplifier 17 are controlled to be in the ON state, and during the duplex instruction and the transmission instruction in the case of simplex.
Is operated so that the transmission output is guided to the bandpass filter 6 in cooperation with the high frequency switch circuit 7.

The switch control circuit 13 selectively applies the voltage from the power supply circuit to the terminal C of the intermediate frequency switch circuit 10 as shown in FIG. 4, and also applies it to the high frequency amplifier circuit 3 and the mixer circuit 4 to generate a high frequency wave. A transistor Q2 that activates the amplifier circuit 3 and the mixer circuit 4, and a terminal B of the high frequency switch circuit 7 that selectively selects the voltage from the power supply circuit.
And a transistor Q3 which is applied to the terminal D of the intermediate frequency switch circuit 10 and is applied to the high frequency amplifier circuit 8 and the mixer circuit 9 to activate the high frequency amplifier circuit 8 and the mixer circuit 9.

The switch control circuit 13 applies a voltage output from the microcomputer 18 to the base of the transistor Q2 during the duplication instruction to control the transistor Q2 to the ON state during the duplication instruction, thereby performing the duplication instruction. , Controlling the high-frequency amplifier 3 and the mixer circuit 4 to the operating state,
In cooperation with the intermediate frequency switch circuit 10, the intermediate frequency signal output from the mixer circuit 4 is guided to the intermediate frequency amplifier 11,
During the reception instruction in the case of simplex from the microcomputer 18, the output voltage is applied to the base of the transistor Q3 to control the transistor Q3 in the ON state during reception instruction in the case of simplex to perform reception in the case of simplex. During the instruction, the high frequency amplifier 8 and the mixer circuit 9 are controlled to the operating state, and the output from the band pass filter 6 is guided to the high frequency amplifier 8 in cooperation with the high frequency switch circuit 7.
It is configured to cooperate with the intermediate frequency switch circuit 10 to guide the intermediate frequency signal output from the mixer circuit 9 to the intermediate frequency amplifier 11.

The pass frequency characteristics of the band pass filters 2 and 6 are constructed to have the characteristics shown in a and b in FIG.

In the radio transmitter / receiver of the present embodiment configured as described above, when duplex communication is performed, the transistors Q1 and Q2 are controlled to be in the ON state by the output from the microcomputer 18, and the oscillation modulation circuit 16 The power amplifier 17 is controlled to be in the operating state, and the transmission output is guided to the bandpass filter 6 via the high frequency switch circuit 7. Further, the high frequency amplifier 3 and the mixer circuit 4 are controlled to be in an operating state, and are mixed with the frequency (fa-fi) output from the local oscillator 5 in the mixer circuit 4 to be converted into an intermediate frequency of the intermediate frequency fi. The signal is transmitted from the intermediate frequency switch circuit 10 to the intermediate frequency amplifier 1
Guided to 1. Note that when performing duplex communication, the high frequency amplifier 8 and the mixer circuit 9 are not controlled to be in an operating state and are in a non-operating state.

Accordingly, the duplex output communication is performed in which the transmission output of the frequency fb is transmitted and the reception signal of the frequency fa is received. In this case, the attenuation of the signal of the frequency fb in the bandpass filter 2 is large,
There is little attenuation for signals of frequency fa. Therefore, the received signal of the frequency fa input from the antenna 1 is guided to the high frequency amplifier 3 and is amplified by the band pass filter 2 with almost no attenuation. The transmission output has the frequency fb and is greatly attenuated in the bandpass filter 2,
In the high frequency amplifier 3, sensitivity suppression at the frequency fa hardly occurs.

If the leakage power of the frequency fb is high, the sensitivity suppression at the frequency fa occurs in the high frequency amplifier 3, but as described above, since the leakage power of the frequency fb is small, the sensitivity suppression at the frequency fa in the high frequency amplifier 3 is suppressed. There is no such thing as described above.

The output of the high frequency amplifier 3 is frequency-converted into an intermediate frequency signal having a frequency fi in the mixer circuit 4, supplied to the intermediate frequency amplifier 11 via the intermediate frequency switch circuit 10, amplified, and demodulated in the demodulator 12. Is output. In this case, since the high frequency amplifier 8 and the mixer circuit 9 are controlled in the non-operating state even if the isolation in the intermediate frequency switch circuit 10 is not large, they act as a large attenuator and the frequency fb
The leakage of the transmission output of is extremely small. As a result, the high-frequency amplifier 3, the mixer circuit 4, and the intermediate-frequency amplifier 11 can be received with high sensitivity without being affected by these leaks.

For simplex communication, the high frequency amplifier 3
And the mixer circuit 4 is not controlled to the operating state and is in the non-operating state, and the high frequency amplifier 8 and the mixer circuit 9 are not controlled to the operating state during the transmission instruction and is in the non-operating state.
The switch control circuit 14 controls the power amplifier 17 and the oscillation modulation circuit 16 to be in an operating state, and the power amplifier 17 outputs a modulated output obtained by modulating the frequency fb. Further, the transmission output is guided to the bandpass filter 6 by the high frequency switch circuit 7, and is transmitted through the antenna 1 to the frequency fb.
Sent by.

In the case of simplex communication, during the reception instruction, the switch control circuit 14 does not control the power amplifier 17 and the oscillation modulation circuit 16 to be in the operating state and is in the non-operating state. Further, the switch control circuit 13 controls the high-frequency amplifier 8 and the mixer circuit 9 to the operating state, the high-frequency switch circuit 7 is controlled so as to guide the output from the bandpass filter 6 to the high-frequency amplifier 8, and the intermediate-frequency switch circuit 10 is The frequency fl (= fb output from the local oscillator 5 in the mixer circuit 9 is controlled so that the intermediate frequency signal from the mixer circuit 9 is guided to the intermediate frequency amplifier 11.
-Fi) is frequency-mixed and converted into an intermediate frequency of the intermediate frequency fi, guided to the intermediate frequency amplifier 11, amplified, demodulated in the demodulator 12 and output. Therefore, the received signal of the frequency fb is received with high sensitivity.
In this way, simplex communication can be performed.

[0028]

As described above, according to the present invention, the transmission output is greatly attenuated by the first bandpass filter during the communication by the duplex, and the first receiving section receives the first output.
Desensitization at the center frequency is almost eliminated, and even if the isolation in the selection means is poor in this case, since the second receiving section is in the inoperative state, these become large attenuators. There is an effect that the leakage of the transmission output at the center frequency is extremely reduced. Further, for this reason, there is an effect that the first receiving section and the amplifier connected to the selecting means are not affected by the leakage, and high-sensitivity reception can be performed.

Further, since the control means can be constituted by the diode switch circuit and the transistor switch means, there is also an effect that the constitution is simple.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a wireless transceiver according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a high frequency switch circuit in a wireless transceiver according to an embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration of an intermediate frequency switch circuit in the wireless transceiver according to the exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a switch control circuit in the wireless transceiver according to the exemplary embodiment of the present invention.

FIG. 5 is a frequency characteristic diagram of a bandpass filter in a wireless transceiver according to an embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional wireless transceiver.

[Explanation of symbols]

 2 and 6 band pass filter 3 and 8 high frequency amplifier 4 and 9 mixer circuit 5 local oscillator 7 high frequency switch circuit 10 intermediate frequency switch circuit 11 intermediate frequency amplifier 12 demodulator 13 and 14 switch control circuit 16 oscillation modulation circuit 17 power amplifier 18 micro Computer

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[Procedure amendment]

[Submission date] October 6, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (2)

[Claims] 1. A wireless transmitter / receiver capable of switching between duplex communication and simplex communication, wherein first and second bandpass filters connected to an antenna and having different center frequencies, and a first bandpass filter. A receiver for amplifying an output from the converter and converting it to an intermediate frequency, a switching means connected to the second bandpass filter, and a reception signal from the second bandpass filter for receiving via the switching means. From the first and second receiving sections, the second receiving section that amplifies and converts to an intermediate frequency, the transmitting section that sends out and transmits the transmission output of the center frequency of the second bandpass filter through the switching means, And a switching means for switching the first receiving section to the operating state, the second receiving section to the non-operating state, the transmitting section to the operating state, in the case of duplex communication. The output of the transmitting section is guided to the second band pass filter and the selecting means is controlled to select the output of the first receiving section, and when the simplex transmission is performed, the first and second receiving sections are set to non-operation. In the operating state, the transmitting unit is controlled in the operating state, and the switching means is controlled to guide the output of the transmitting unit to the second bandpass filter.
In the non-operating state, the second receiving section in the operating state, the switching means in the state of guiding the output of the second bandpass filter to the second receiving section, and the selecting means in the second state. A radio transmitter / receiver, comprising: a control unit that controls an output of the receiving unit to a state of being selected. 2. The wireless transceiver according to claim 1, wherein:
The control means includes a first diode switch circuit that guides the transmission output from the transmission unit to the second bandpass filter, and a second diode switch circuit.
The output of the band pass filter of the second to the second receiving unit
And a fourth diode switch circuit for selecting the output of the first receiving section, a fourth diode switch circuit for selecting the output of the second receiving section, and First when sending by communication
Controlling the diode switch circuit in the ON state and supplying power to the transmitting section, and turning on the third diode switch circuit in the duplex communication and the first receiving section. Second transistor switch means for supplying power to the third transistor, and a third transistor for controlling the second and fourth diode switch circuits to be in an ON state when receiving by simplex and supplying power to the second receiving section. A wireless transceiver, comprising: a switch means.