阅读说明：本技术 一种带有自检系统的线性高功率放大器及供电方法 (Linear high-power amplifier with self-checking system and power supply method ) 是由 李春利 于海龙 叶彬 郝勇博 孙满盈 于 2021-08-23 设计创作，主要内容包括：本发明涉及一种带有自检系统的线性高功率放大器,包括功率放大模块、电源模块、功放自检系统和功率输出模块,所述功率放大模块的输出端与功放自检系统的输入端、功率输出模块的输入端电连接,所述电源模块的输出端与功率放大模块的输入端、功放自检系统的输入端电连接,所述功率放大模块包括依次串联的前级放大单元、中级放大单元和末级放大单元,所述功率输出模块包括隔离器和滤波器,所述功放自检系统包括单片机模块、信号采集模块、PTT控制电路和上位机。本发明具有输出效率高的效果,同时具有自检保护功能,能够有效降低功放设备的故障率并降低成本。(The invention relates to a linear high-power amplifier with a self-checking system, which comprises a power amplification module, a power supply module, a power amplifier self-checking system and a power output module, wherein the output end of the power amplification module is electrically connected with the input end of the power amplifier self-checking system and the input end of the power output module, the output end of the power supply module is electrically connected with the input end of the power amplification module and the input end of the power amplifier self-checking system, the power amplification module comprises a preceding stage amplification unit, a middle stage amplification unit and a final stage amplification unit which are sequentially connected in series, the power output module comprises an isolator and a filter, and the power amplifier self-checking system comprises a single chip microcomputer module, a signal acquisition module, a PTT control circuit and an upper computer. The invention has the effect of high output efficiency, has the self-checking protection function, and can effectively reduce the failure rate of the power amplifier equipment and reduce the cost.)

1. A linear high power amplifier with a self-test system, characterized by: the power amplifier comprises a power amplification module, a power supply module, a power amplifier self-checking system and a power output module, wherein the output end of the power amplification module is electrically connected with the input end of the power amplifier self-checking system and the input end of the power output module;

the power amplification module comprises a preceding stage amplification unit, a middle stage amplification unit and a final stage amplification unit which are sequentially connected in series, the pre-stage amplification unit comprises a low-noise radio frequency power tube, the middle-stage amplification unit comprises an LDMOS radio frequency power tube, the final-stage amplifying unit comprises a GaN radio-frequency power tube, an input coupler, a first balun circuit, a second balun circuit and an output coupler, the input end of the input coupler is electrically connected with the output end of the intermediate-stage amplifying unit, the output end of the input coupler is electrically connected with the input end of the first balun circuit, the output end of the first balun circuit is electrically connected with the input end of a GaN radio frequency power tube, the output end of the GaN radio frequency power tube is electrically connected with the input end of a second balun circuit, and the output end of the second balun circuit is electrically connected with the input end of the output coupler;

the power output module comprises an isolator and a filter, wherein the input end of the isolator is electrically connected with the output end of the output coupler, and the output end of the isolator is electrically connected with the input end of the filter;

the power amplifier self-checking system comprises a single chip microcomputer module, a signal acquisition module, a PTT control circuit and an upper computer, wherein the output end of the single chip microcomputer module is connected with the input end of the PTT control circuit, the single chip microcomputer module is connected with the upper computer, the signal acquisition module comprises a temperature detection module, a voltage detection module, a standing wave detection module and an excitation detection module, the temperature detection module comprises a temperature switch and a temperature sensor, the output end of the temperature sensor is electrically connected with the input end of the single chip microcomputer module, the output end of the temperature switch is electrically connected with the input end of the PTT control circuit, the voltage detection module comprises a voltage division circuit module, the output end of the voltage division circuit module is electrically connected with the input end of the single chip microcomputer module, the standing wave detection module comprises an operational amplifier comparator, the output end of the operational amplifier comparator is electrically connected with the input end of the single chip microcomputer module, the excitation detection module comprises a detection circuit module, and the output end of the detection circuit module is electrically connected with the input end of the single chip microcomputer module;

the power module comprises a high-voltage current limiter, a current-limiting resistor, a field-effect switch tube, a positive-voltage power module and a negative-voltage power module, wherein the output end of the current-limiting resistor is electrically connected with the input end of the high-voltage current limiter, the output end of the high-voltage current limiter is electrically connected with the input end of the field-effect switch tube, the output end of the field-effect switch tube is electrically connected with the input end of the power amplification module, the output end of the positive-voltage power module is electrically connected with the input end of the power amplification module and the input end of the power amplification self-checking system, and the output end of the negative-voltage power module is electrically connected with the input end of the power amplification module.

2. The linear high power amplifier with self-test system according to claim 1, characterized in that: the low-noise radio-frequency power tubes are GaAs radio-frequency power tubes, the number of the low-noise radio-frequency power tubes is three, the three low-noise radio-frequency power tubes are sequentially connected in series and amplify step by step, the gains of the first two low-noise radio-frequency power tubes are 15dB, and the gain of the other low-noise radio-frequency power tube is 17.8 dB.

3. The linear high power amplifier with self-test system according to claim 1, characterized in that: the LDMOS radio-frequency power tube comprises two LDMOS radio-frequency power tubes, the two LDMOS radio-frequency power tubes are connected in series and amplify step by step, the power of the former LDMOS radio-frequency power tube is 10w, the gain of the former LDMOS radio-frequency power tube is 16dB, and the power of the latter LDMOS radio-frequency power tube is 20w, and the gain of the latter LDMOS radio-frequency power tube is 17.5 dB.

4. The linear high power amplifier with self-test system according to claim 1, characterized in that: the GaN radio frequency power tubes are four, the four GaN radio frequency power tubes are connected in parallel, the power of the four GaN radio frequency power tubes is 150w, and the gain of the four GaN radio frequency power tubes is 13 dB.

5. The linear high power amplifier with self-test system according to claim 4, characterized in that: the number of the first balun circuits and the number of the second balun circuits are two, each first balun circuit corresponds to two GaN radio frequency power tubes, and each second balun circuit corresponds to two GaN radio frequency power tubes.

6. The linear high power amplifier with self-test system according to claim 1, characterized in that: the first balun circuit and the second balun circuit both adopt coaxial line baluns, and the coaxial line baluns are formed by sleeving a coaxial cable on a ferrite magnetic core or winding the coaxial cable on the magnetic core.

7. The linear high power amplifier with self-test system according to claim 1, characterized in that: the input coupler and the output coupler both adopt 90-degree bridge couplers.

8. The linear high power amplifier with self-test system according to claim 1, characterized in that: the single chip microcomputer module adopts an STM32 single chip microcomputer, the single chip microcomputer module is communicated with RS232 of the upper computer through an RS232 interface, and the single chip microcomputer module is communicated with RS485 of the upper computer through an RS485 interface.

9. A method of powering a linear high power amplifier with a self-test system according to any of the claims 1 to 8, characterized in that: the power amplifier is characterized in that the input ends of the field effect switch tube and the positive voltage power supply module are electrically connected with a secondary voltage-stabilized power supply, the output end of the field effect switch tube is electrically connected with the drain electrode of the LDMOS radio frequency power tube and the drain electrode of the GaN radio frequency power tube, the output end of the positive voltage power supply module is electrically connected with the grid electrode of the LDMOS radio frequency power tube, the low-noise radio frequency power tube and the input end of the power amplifier self-checking system, the output end of the negative voltage power supply module is electrically connected with the grid electrode of the GaN radio frequency power tube, and the source levels of the LDMOS radio frequency power tube and the GaN radio frequency power tube are all grounded.

10. A method of powering a linear high power amplifier with self-test system according to claim 9, characterized in that: the voltage provided by the secondary voltage-stabilized power supply is +50V, the voltage provided by the positive voltage power supply module is +5V, and the voltage provided by the negative voltage power supply module is-5V.

Technical Field

The invention belongs to the technical field of microwave power amplifiers, and particularly relates to a linear high-power amplifier with a self-checking system and a power supply method.

Background

With the rapid development of wireless communication technology, wireless communication transmitters such as radars and base stations are widely used, in the wireless communication transmitters, in order to overcome transmission loss and expand the signal radiation range, a radio frequency signal needs to be amplified to a specified power by a power amplifier and radiated to the outside through an antenna, the power amplifier is used as a core component of a wireless communication system, the performance of the power amplifier directly affects the indexes such as output power, linearity and working bandwidth of the transmitter system, in recent years, semiconductor materials are rapidly developed, researches show that GaN materials have the advantages of large forbidden bandwidth, excellent electron mobility, high saturated electron drift velocity and the like, GaN radio frequency power amplifiers are widely applied to application scenes of high frequency bandwidth, but the output power of the existing GaN radio frequency power amplifier is low and the working environment of the power amplifier is severe, are prone to failure and thus cause high costs.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a linear high-power amplifier with a self-checking system and a power supply method, which have the effects of high output efficiency and self-checking protection function, can effectively reduce the failure rate of power amplifier equipment and reduce the cost.

The technical scheme adopted by the invention is as follows: a linear high-power amplifier with a self-checking system comprises a power amplification module, a power supply module, a power amplifier self-checking system and a power output module, wherein the output end of the power amplification module is electrically connected with the input end of the power amplifier self-checking system and the input end of the power output module;

the power amplification module comprises a preceding stage amplification unit, a middle stage amplification unit and a final stage amplification unit which are sequentially connected in series, the pre-stage amplification unit comprises a low-noise radio frequency power tube, the middle-stage amplification unit comprises an LDMOS radio frequency power tube, the final-stage amplifying unit comprises a GaN radio-frequency power tube, an input coupler, a first balun circuit, a second balun circuit and an output coupler, the input end of the input coupler is electrically connected with the output end of the intermediate-stage amplifying unit, the output end of the input coupler is electrically connected with the input end of the first balun circuit, the output end of the first balun circuit is electrically connected with the input end of a GaN radio frequency power tube, the output end of the GaN radio frequency power tube is electrically connected with the input end of a second balun circuit, and the output end of the second balun circuit is electrically connected with the input end of the output coupler;

the power output module comprises an isolator and a filter, wherein the input end of the isolator is electrically connected with the output end of the output coupler, and the output end of the isolator is electrically connected with the input end of the filter;

the power amplifier self-checking system comprises a single chip microcomputer module, a signal acquisition module, a PTT control circuit and an upper computer, wherein the output end of the single chip microcomputer module is connected with the input end of the PTT control circuit, the single chip microcomputer module is connected with the upper computer, the signal acquisition module comprises a temperature detection module, a voltage detection module, a standing wave detection module and an excitation detection module, the temperature detection module comprises a temperature switch and a temperature sensor, the output end of the temperature sensor is electrically connected with the input end of the single chip microcomputer module, the output end of the temperature switch is electrically connected with the input end of the PTT control circuit, the voltage detection module comprises a voltage division circuit module, the output end of the voltage division circuit module is electrically connected with the input end of the single chip microcomputer module, the standing wave detection module comprises an operational amplifier comparator, the output end of the operational amplifier comparator is electrically connected with the input end of the single chip microcomputer module, the excitation detection module comprises a detection circuit module, and the output end of the detection circuit module is electrically connected with the input end of the single chip microcomputer module;

the power module comprises a high-voltage current limiter, a current-limiting resistor, a field-effect switch tube, a positive-voltage power module and a negative-voltage power module, wherein the output end of the current-limiting resistor is electrically connected with the input end of the high-voltage current limiter, the output end of the high-voltage current limiter is electrically connected with the input end of the field-effect switch tube, the output end of the field-effect switch tube is electrically connected with the input end of the power amplification module, the output end of the positive-voltage power module is electrically connected with the input end of the power amplification module and the input end of the power amplification self-checking system, and the output end of the negative-voltage power module is electrically connected with the input end of the power amplification module.

Furthermore, the low-noise radio-frequency power tubes are GaAs radio-frequency power tubes, the number of the low-noise radio-frequency power tubes is three, the three low-noise radio-frequency power tubes are sequentially connected in series and are amplified step by step, the gains of the first two low-noise radio-frequency power tubes are 15dB, and the gain of the other low-noise radio-frequency power tube is 17.8 dB.

Furthermore, the number of the LDMOS radio-frequency power tubes is two, the two LDMOS radio-frequency power tubes are connected in series and amplify step by step, the power of the previous LDMOS radio-frequency power tube is 10w, the gain of the previous LDMOS radio-frequency power tube is 16dB, the power of the next LDMOS radio-frequency power tube is 20w, and the gain of the next LDMOS radio-frequency power tube is 17.5 dB.

Furthermore, four GaN radio frequency power tubes are arranged and connected in parallel, the power of each GaN radio frequency power tube is 150w, and the gain of each GaN radio frequency power tube is 13 dB.

Furthermore, the number of the first balun circuits and the number of the second balun circuits are two, each first balun circuit corresponds to two GaN radio frequency power tubes, and each second balun circuit corresponds to two GaN radio frequency power tubes.

Furthermore, the first balun circuit and the second balun circuit both adopt coaxial line baluns, and the coaxial line baluns are formed by sleeving a coaxial cable on a ferrite magnetic core or winding the coaxial cable on the magnetic core.

Further, the input coupler and the output coupler both adopt 90-degree bridge couplers.

Further, the single chip microcomputer module adopts an STM32 single chip microcomputer, the single chip microcomputer module is communicated with RS232 of the upper computer through an RS232 interface, and the single chip microcomputer module is communicated with RS485 of the upper computer through an RS485 interface.

According to the power supply method of the linear high-power amplifier with the self-checking system, the input ends of the field-effect switch tube and the positive-voltage power supply module are electrically connected with the secondary voltage-stabilizing power supply, the output end of the field-effect switch tube is electrically connected with the drain electrode of the LDMOS radio-frequency power tube and the drain electrode of the GaN radio-frequency power tube, the output end of the positive-voltage power supply module is electrically connected with the grid electrode of the LDMOS radio-frequency power tube, the low-noise radio-frequency power tube and the input end of the power amplifier self-checking system, the output end of the negative-voltage power supply module is electrically connected with the grid electrode of the GaN radio-frequency power tube, and the source levels of the LDMOS radio-frequency power tube and the GaN radio-frequency power tube are both grounded.

Preferably, the voltage provided by the secondary voltage-stabilized power supply is +50V, the voltage provided by the positive voltage power supply module is +5V, and the voltage provided by the negative voltage power supply module is-5V.

The invention has the beneficial effects that: the invention amplifies the input power step by step through the pre-stage, middle-stage and final-stage amplifying units, and outputs the amplified input power after being gradually synthesized through the second balun circuit and the output coupler, thereby effectively improving the output power.

Drawings

FIG. 1 is a functional block diagram of the present invention;

FIG. 2 is a schematic diagram of a power amplification module according to the present invention;

FIG. 3 is a topology diagram of the final amplification unit and power output module of the present invention;

fig. 4 is a flow chart of the power amplifier self-checking system according to the present invention;

FIG. 5 is a flow chart of the power module of the present invention.

In the figure: 1. a low-noise radio-frequency power tube 2, an LDMOS radio-frequency power tube 3 and a GaN radio-frequency power tube.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments of the present invention, belong to the protection scope of the present invention, and are specifically described below with reference to the embodiments.

Example 1

As shown in fig. 1, the present invention includes a linear high power amplifier with a self-checking system, which includes a power amplification module, a power supply module, a power amplifier self-checking system and a power output module, wherein an output end of the power amplification module is electrically connected to an input end of the power amplifier self-checking system and an input end of the power output module, and an output end of the power supply module is electrically connected to an input end of the power amplification module and an input end of the power amplifier self-checking system.

As shown in fig. 2 and 3, the power amplification module includes a pre-stage amplification unit, a middle-stage amplification unit and a final-stage amplification unit which are sequentially connected in series, the pre-stage amplification unit includes a low-noise rf power tube 1, the low-noise rf power tube 1 is a GaAs rf power tube, the low-noise rf power tube 1 is provided with three, the three low-noise rf power tubes 1 are sequentially connected in series and amplify step by step, the first two low-noise rf power tubes 1 have a gain of 15dB, the other low-noise rf power tube 1 has a gain of 17.8dB, the three low-noise rf power tubes 1 perform step by step amplification for increasing the gain while ensuring gain flatness and input and output standing waves, the actual gain of the pre-stage amplification unit is about 35dB due to input and output matching loss, the middle-stage amplification unit includes an LDMOS rf power tube 2, the LDMOS power tubes 2 are provided with two, the two LDMOS radio-frequency power tubes 2 are connected in series and are amplified step by step, the power of the previous LDMOS radio-frequency power tube 2 is 10w, the gain is 16dB, the power of the next LDMOS radio-frequency power tube 2 is 20w, the gain is 17.5dB, the two LDMOS radio-frequency power tubes 2 are amplified step by step and are mainly used for driving radio-frequency signals to ensure that the final stage has enough pushing power, the actual gain of a middle-stage amplification unit is about 17dB due to input and output matching loss, the final-stage amplification unit comprises GaN radio-frequency power tubes 3, the four GaN radio-frequency power tubes 3 are arranged, the four GaN radio-frequency power tubes 3 are connected in parallel, the power of the four GaN radio-frequency power tubes 3 is 150w, the gain is 13dB, the actual gain of the final-stage amplification unit is about 13dB due to input and output matching loss, and the radio-frequency signals of 12dBm are amplified step by step after being amplified by a power amplification module, the output end signal is about 53dBm, the final stage amplifying unit further comprises an input coupler, a first balun circuit, a second balun circuit and an output coupler, the input coupler and the output coupler both adopt 90-degree bridge couplers, the input end of the input coupler is electrically connected with the output end of the intermediate stage amplifying unit, the output end of the input coupler is electrically connected with the input end of the first balun circuit, the output end of the first balun circuit is electrically connected with the input end of a GaN radio frequency power tube 3, the output end of the GaN radio frequency power tube 3 is electrically connected with the input end of the second balun circuit, the output end of the second balun circuit is electrically connected with the input end of the output coupler, two first balun circuits and two second balun circuits are arranged, each first balun circuit corresponds to two GaN radio frequency power tubes 3, each second balun circuit corresponds to two GaN radio frequency power tubes 3, the input coupler divides the signal of the middle-stage amplifying unit into two paths of radio frequency signals, four paths of radio frequency signals are formed after the signals are respectively processed by two first balun circuits and are input into four GaN radio frequency power tubes 3, the radio frequency signals are amplified and then synthesized by a second balun circuit and are then sent into the output coupler for further synthesis, the first balun circuit and the second balun circuit both adopt coaxial line baluns, the coaxial line baluns are formed by sleeving coaxial cables on ferrite magnetic cores or winding the coaxial cables on the magnetic cores, and different transformation effects are achieved through different winding modes between the coaxial lines.

The power output module comprises an isolator and a filter, the input end of the isolator is electrically connected with the output end of the output coupler, the output end of the isolator is electrically connected with the input end of the filter, when the power amplifier reflects power, the isolator can absorb the reflected power to protect the safety of the GaN radio frequency power tube 3, when the power amplifier works normally, the isolator can receive signals in the output coupler and output the signals finally, and the filter can filter waveforms to remove redundant harmonic components.

As shown in fig. 4, the power amplifier self-checking system comprises a single chip microcomputer module, a signal acquisition module, a PTT control circuit and an upper computer, wherein the single chip microcomputer module adopts an STM32 single chip microcomputer, an output end of the single chip microcomputer module is connected with an input end of the PTT control circuit, the STM32 single chip microcomputer processes information obtained by the signal acquisition module and controls the PTT to protect the whole circuit, the PTT control circuit comprises a gate circuit and an analog switch, the single chip microcomputer module detects that the working state of the power amplifier is abnormal, controls an enabling pin of the gate circuit to close the analog switch, is connected with the upper computer, the upper computer can adopt software with a serial port reading function written by a computer, the single chip microcomputer module communicates with an RS232 interface of the upper computer through an RS232 interface, communicates with an RS485 interface of the upper computer through an RS485 interface, and the signal acquisition module comprises a temperature detection module, The temperature detection module comprises a temperature switch and a temperature sensor, the output end of the temperature sensor is electrically connected with the input end of the single chip microcomputer module, the temperature sensor converts the temperature into the voltage and sends the voltage to the temperature detection pin of the single chip microcomputer module, the temperature sensor reads the voltage by using the AD function of the single chip microcomputer module, the judgment is carried out by using the C language code written in the single chip microcomputer module, the enabling pin of the analog switch in the PTT is closed when the working temperature of the power amplifier is abnormal, the output end of the temperature switch is electrically connected with the input end of the PTT control circuit, when the temperature switch detects that the temperature exceeds the alarm temperature set by the temperature switch, the temperature switch controls the gate circuit of the PTT control circuit to close the enabling pin of the analog switch, the voltage detection module comprises a voltage division circuit module, and the output end of the voltage division circuit module is electrically connected with the input end of the single chip microcomputer module, the single chip microcomputer module reads the partial pressure of the input voltage through the AD function and then restores the partial pressure into the input voltage for judgment, the enabling pin of the analog switch in the PTT control circuit is closed when the working voltage is abnormal, the standing wave detection module comprises an operational amplifier comparator, the output end of the operational amplifier comparator is electrically connected with the input end of the single chip microcomputer module, in the embodiment, the standing wave detection scheme adopts a comparator scheme, namely, the operational amplifier comparator is used for calculation, the output pin of the operational amplifier comparator is at a high level when the standing wave is abnormal, the single chip microcomputer module reads the level state of the operational amplifier comparator and judges whether the standing wave is normal or not, the enabling pin of the analog switch in the PTT control circuit is closed when the standing wave is abnormal, the excitation detection module comprises a detection circuit module, the output end of the detection circuit module is electrically connected with the input end of the single chip microcomputer module, and the power is converted into the detection voltage through a detection tube, when the detection voltage power is too large, the operational amplifier comparator is controlled to generate a high level signal, the single chip microcomputer module reads the level state of the operational amplifier comparator to judge whether excitation is normal or not, and an enabling pin of an analog switch in the PTT control circuit is closed when excitation is abnormal.

As shown in fig. 5, the power module includes a high voltage current limiter, a current limiting resistor, a field effect switch tube, a positive voltage power module and a negative voltage power module, the positive voltage power module is composed of a forward power chip and its peripheral circuit, the negative voltage power module is composed of a reverse power chip and its peripheral circuit, the output end of the current limiting resistor is electrically connected with the input end of the high-voltage current limiter, the output end of the high-voltage current limiter is electrically connected with the input end of the field effect switch tube, the high-voltage current limiter acquires the voltage and current state of the power amplifier through the current limiting resistor, and controls the working state of the field effect switch tube according to the state, the output end of the field effect switch tube is electrically connected with the input end of the power amplification module, the output end of the positive-pressure power supply module is electrically connected with the power amplification module and the input end of the power amplifier self-checking system, and the output end of the negative-pressure power supply module is electrically connected with the input end of the power amplification module.

The power supply method of the linear high-power amplifier with the self-checking system is characterized in that the input ends of the field-effect switch tube and the positive-voltage power supply module are electrically connected with a secondary stabilized voltage supply, the voltage provided by the secondary stabilized voltage supply is +50V, the voltage is sent to the drain electrode of the LDMOS radio-frequency power tube 2 and the drain electrode of the GaN radio-frequency power tube 3 in the power amplification module through the field-effect switch tube to provide the drain electrode voltage, the output end of the field-effect switch tube is electrically connected with the drain electrode of the LDMOS radio-frequency power tube 2 and the drain electrode of the GaN radio-frequency power tube 3, the output end of the positive-voltage power supply module is electrically connected with the grid electrode of the LDMOS radio-frequency power tube 2, the low-noise radio-frequency power tube 1 and the input end of the power amplification self-checking system, the voltage provided by the positive-voltage power supply module is +5V to supply power to the low-noise radio-frequency power tube 1 and supply the grid electrode of the LDMOS radio-frequency power tube 2, and the output end of the negative-voltage power supply module is electrically connected with the grid electrode of the GaN radio-frequency power tube 3, the negative voltage power supply module supplies-5V voltage to supply power for the grid voltage of the GaN radio-frequency power tube 3, and the source levels of the LDMOS radio-frequency power tube 2 and the GaN radio-frequency power tube 3 are both grounded.

According to the invention, the input power is amplified step by step through the pre-stage amplifying unit, the intermediate-stage amplifying unit and the final-stage amplifying unit, and is output after being gradually synthesized through the second balun circuit and the output coupler, so that the output power can be effectively improved, whether the information acquired by the signal acquisition module is abnormal or not can be timely known through the single chip microcomputer module, and the analog switch in the PTT control circuit is controlled to close the enabling pin when the information is abnormal, so that the circuit protection effect is achieved, the fault rate of the power amplifier equipment is effectively reduced, and the maintenance cost is reduced.

Example 2

On the basis of the embodiment 1, the standing wave detection scheme adopts a standing wave ratio calculation scheme to replace the comparator scheme in the embodiment 1, an operational amplifier comparator is not needed, the process is simplified, the equipment cost is reduced, the standing wave ratio calculation scheme reads forward voltage V + and reflected voltage V-through a single chip microcomputer module and calculates the standing wave ratio, and an enabling pin of an analog switch in a PTT control circuit is closed when the standing wave ratio is abnormal.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.