Transmitter switch to start and stop the power amplifier circuit

Abstract

The present invention relates to a power amplifier circuit for starting and stopping a transmitter switch, which includes a level sensor chip. The 1st pin of the level sensor chip is used as a signal input terminal and is connected to an audio signal through a capacitor C2. The 2nd pin is connected to the 3rd pin through a variable resistor VR2. The 3rd, 4th, and 5th pins are grounded. The 6th pin is used as a signal output terminal. On the one hand, it is connected to the 2nd pin of a board J1. On the other hand, it is successively connected to a light-emitting diode D6, a light-emitting diode D5, and a resistor R3. The other end of the resistor R3 is connected to the 6th pin of the board J1. The 3rd pin of the board J1 is respectively connected to the capacitor C2 and the signal input terminal of a switch high-voltage circuit. The 4th pin is connected to the high-low voltage inverting input terminal of the switch high-voltage circuit. The 5th pin is connected to the signal output terminal of the switch high-voltage circuit. This device adopts digital design, simplifies the circuit structure, reduces or eliminates the manual adjustment link, eliminates potential damage hazards, enhances the applicable performance, and improves the circuit sensitivity, response speed, and working stability.

Description

Technical Field

[0001] This patent application belongs to the technical field of communication equipment. More specifically, it relates to a transmitter switch start-stop power amplifier circuit. Background Art

[0002] Guangzhou Coast Radio Station (Guangzhou Communication Center) is the largest and most fully functional coast radio station in South China. It represents the country in participating in the International Convention for the Safety of Life at Sea (SOLAS), fulfills the responsibilities and obligations stipulated by the International Maritime Organization (IMO), and undertakes the task of ship safety communication and watchkeeping in the entire South China Sea. It mainly undertakes three major communication services: distress safety watchkeeping, safety information dissemination, and ship public radio communication. There are 42 JRC transmitters in use at Guangzhou Coast Radio Station, including 13 ten-kilowatt transmitters and 29 five-kilowatt transmitters. This part of the transmitters covers all types of emission services in the center. Among them, services such as DSC, NAVTEX, SSB, and weather fax are broadcast irregularly or intermittently, and there is no idle signal during non-broadcast periods. Currently, the signals sent from the central control system of the center to the transmitter station do not have independent switch high-voltage and start-stop power amplifier control signals. The high voltage of the transmitter needs to be kept on all the time to ensure normal transmission of the transmitter when there is a service signal. This will accelerate the aging and depreciation of the equipment hardware, and at the same time increase the possibility of human error operation.

[0003] Regarding the KEY&PTT signals for controlling the start-stop of the transmitter power amplifier, the current solution is to use the "amplification - rectification - voltage division sampling - analog switch" method to generate KEY&PTT signals by converting audio (AF) signals and connect them to the corresponding interfaces of the transmitter for use. This circuit design method has certain deficiencies: mainly designed in an analog way, which requires manual adjustment and the parameter adjustment indicators are not clear enough; the circuit sensitivity and response speed are average; after long-term use, individual capacitors in the circuit are burned out. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a transmitter switch start-stop power amplifier circuit, which does not require manual adjustment, loads the power amplifier high voltage only when there is a service signal, controls the output power of the whole machine, and shuts down the power amplifier high voltage of the transmitter when there is no service signal. It can effectively reduce the total power consumption during the operation of the transmitter, save the operation cost, reduce the operation noise of the transmitter, reduce the depreciation loss of components, and reduce the risk of human error operation or omission.

[0005] To solve the above problems, the technical solution adopted by the present invention is:

[0006] A transmitter switch start-stop power amplifier circuit, electrically connected to an audio signal, includes a level sensor chip. The 1st pin of the level sensor chip serves as a signal input terminal and is connected to the audio signal through a capacitor C2. The 2nd pin of the level sensor chip is connected to the 3rd pin of the level sensor chip through a variable resistor VR2. The 3rd pin of the level sensor chip is grounded through a capacitor C4. The 4th pin of the level sensor chip is grounded. The 5th pin of the level sensor chip is grounded through a capacitor C6. The 6th pin of the level sensor chip serves as a signal output terminal;

[0007] The 6th pin of the level sensor chip is connected to the 2nd pin of a board J1 on one hand. On the other hand, the 6th pin of the level sensor chip is successively connected to a light-emitting diode D6, a light-emitting diode D5, and a resistor R3. The other end of the resistor R3 is connected to the 6th pin of the board J1. The 1st pin of the board J1 is grounded, and the 3rd pin is respectively connected to the capacitor C2 and the signal input terminal of a switch high-voltage circuit. The 4th pin is connected to the high-low voltage inverting input terminal of the switch high-voltage circuit. The 5th pin is connected to the signal output terminal of the switch high-voltage circuit;

[0008] The 3rd pin of the board J1 outputs an audio signal.

[0009] A further improvement in the technical solution of the present invention lies in that the model of the level sensor chip is NJM2072.

[0010] A further improvement in the technical solution of the present invention lies in that the light-emitting diode D5 is a yellow light-emitting diode.

[0011] A further improvement in the technical solution of the present invention lies in that the capacitor C6 is a polar capacitor.

[0012] A further improvement in the technical solution of the present invention lies in that the nominal value of the variable resistor VR2 is 100 KΩ.

[0013] Due to the adoption of the above technical solution, the beneficial effects obtained by the present invention are:

[0014] The present invention upgrades the existing KEY&PTT signal conversion circuit, can utilize the existing switch high-voltage circuit, and can also integrate a new high-voltage switch control circuit. It uses an audio (AF) signal to convert and generate signals for controlling the transmitter switch high-voltage and starting and stopping the power amplifier, controls the transmitter to start and stop the high-voltage and transmit signals, improves and optimizes the KEY&PTT signal conversion performance, and avoids the long-term on situation of PA PWR (power amplification) and KEY&PTT (Push to Hold). When there is a service signal arriving, the power amplifier high-voltage is loaded and the output power of the whole machine is controlled. When there is no service signal, the transmitter turns off the power amplifier high-voltage, which can effectively reduce the total power consumption of the transmitter during operation, save operation costs, reduce the operation noise of the transmitter, reduce the depreciation loss of components, and reduce the risk of human misoperation or omission.

[0015] The circuit of the present invention is dedicated to independent design at the hardware level by combining modular chips and discrete components, upgrading and revising the KEY&PTT conversion circuit, designing it in a digital manner, further simplifying the circuit structure, reducing or eliminating the manual adjustment link, eliminating the hidden danger of capacitor damage in the original design, enhancing the applicability, and improving the circuit sensitivity, response speed and working stability. And a PA ON signal control module is manufactured and integrated into the KEY&PTT and PA ON integrated signal control module, which is added and installed in the transmitter, and the output control signal is sent to the corresponding port or access point of the transmitter, and the high-voltage switch and the start-stop power amplifier of the transmitter are controlled in real time according to the service audio signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the circuit diagram of the transmitter control board of the present invention;

[0017] Figure 2 is the schematic diagram of the control circuit of the present invention;

[0018] Figure 3 is the signal waveform diagram of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be further described in detail below with reference to the embodiments.

[0020] The present invention discloses a circuit for starting and stopping the power amplifier of a transmitter. For the specific circuit layout, please refer to Figures 1 - 3 , Figure 1 is the circuit layout diagram drawn for the convenience of PCB manufacturing, Figure 2 is the schematic diagram from the perspective of function realization.

[0021] is electrically connected to the audio signal, including a level sensor chip. The pin 1 of the level sensor chip is used as the signal input terminal and is connected to the audio signal through the capacitor C2. The pin 2 of the level sensor chip is connected to the pin 3 of the level sensor chip through the adjustable resistor VR2. The pin 3 of the level sensor chip is grounded through the capacitor C4. The pin 4 of the level sensor chip is grounded. The pin 5 of the level sensor chip is grounded through the capacitor C6. The pin 6 of the level sensor chip is used as the signal output terminal.

[0022] On the one hand, the pin 6 of the level sensor chip is connected to the pin 2 of the board J1. On the other hand, the pin 6 of the level sensor chip is sequentially connected to the light-emitting diode D6, the light-emitting diode D5, and the resistor R3. The other end of the resistor R3 is connected to the pin 6 of the board J1. The pin 1 of the board J1 is grounded, and the pin 3 is respectively connected to the capacitor C2 and the signal input terminal of the high-voltage switch circuit. The pin 4 is connected to the high-low voltage inverting input terminal of the high-voltage switch circuit. The pin 5 is connected to the signal output terminal of the high-voltage switch circuit;

[0023] The pin 3 of the board J1 outputs an audio (AF) signal.

[0024] Preferably, the level sensor chip model is NJM2072, the light-emitting diode D5 is a yellow light-emitting diode, the capacitor C6 is a polarized capacitor (22 μF), the nominal value of the adjustable resistor VR2 is 100 KΩ. The capacitor C4 is 104 pF, the capacitor C2 is 10 μF, the light-emitting diodes D6 and D5 are of the IN4148 model, and the resistor R3 is 1 KΩ.

[0025] The transmitter switch start-stop power amplifier circuit of the present invention can be used in combination with the transmitter switch high-voltage circuit in the figure. The transmitter switch high-voltage circuit is shown in the figure and will not be elaborated here.

[0026] Circuit working principle:

[0027] For the KEY&PTT start-stop power amplifier function, the audio (AF) signal enters through pin 1 of the signal level sensor chip U2 (NJM2072, voice control circuit) and is output through pin 6. When an audio service signal enters, pin 6 suddenly drops from a high level to a low level and is output to pin 5 of the transmitter TB2 to control the transmitter power transmission.

[0028] For the PA ON switch high-voltage function, the audio (AF) signal enters through pin 1 of the signal level sensor chip U1 (NJM2072) and is output through pins 6 and 7. Pin 6 of U1 is the high-voltage pulse start pin. When the audio (AF) signal enters, pin 6 is set from a high level to a low level and enters pin 1 (active low) of the retriggerable monostable multivibrator chip U5 (74HC123). On the premise that the reset port of pin 3 is set to a high level, a positive pulse is output from pin 13 to drive the optocoupler U6 to work, and a 5V voltage short pulse is output to the corresponding pin of the exciter PA ON switch key to achieve automatic high-voltage start. Pin 7 of U1 is the high-voltage pulse stop pin. When the audio (AF) signal is cut off, pin 7 is set from a high level to a low level after a short delay. The differentiating circuit built with C7 and R8 (the differentiating circuit formula is ) When R8*C7 is much smaller than T / 2 (where T is the square wave period), a falling-edge sharp-bottom wave is output, and the level is instantly pulled low and sent to pin 2 of the 555 timer chip U3 (pin 2 is the trigger pin, low level is valid). Adjusting the sizes of the external variable resistor VR3 and capacitor C8 can change the delay duration, and it is sent to pin 9 of U5 through pin 3. At this time, it is in the high-voltage state. A low level can be obtained from pin 9 of the transmitter terminal interface board TB3 and connected to the circuit through pin 4 of the board J1 interface. First, it is sent to pin 3 of U5A, and the low level is set to make it in the low-level reset state. Then, after being converted to a high level by the inverter U4 (74AHC1G04), it is sent to pin 11 of U5B to make U5B work. At the same time, after being delayed by the 555 timer chip, a low level will be obtained (in this circuit, the delay time tw = 1.1*VR3*C8). Similarly, a positive pulse is output from port 5 to drive the optocoupler U7 to work, and a 5V voltage short pulse is output to the corresponding pin of the exciter PA ON switch to achieve automatic shutdown of the high voltage.

[0029] Considering the KEY&PTT signals for controlling the start and stop of the power amplifier of the transmitter, the current solution is to use the "amplification - rectification - voltage division sampling - analog switch" method to convert and generate the KEY&PTT signals using the audio (AF) signal and connect them to the corresponding interface of the transmitter for use. There are certain deficiencies in this circuit design method: mainly, it is designed in an analog way, which requires manual adjustment and the parameter adjustment indicators are not clear enough; the circuit sensitivity, stability, and response speed are average; after long-term use, individual capacitors in the circuit are burned out. Therefore, this part of the circuit is upgraded and implemented using a digital method. The response speed of the digital module is faster, the rising edge and falling edge are more vertical and steep, and the response time can reach the ms and us levels; the differential circuit realizes precise and timely triggering; the timer chip module can also calculate and design the required delay duration more accurately; the optocoupler greatly improves the electrical isolation degree through two conversions of electro-optical and opto-electrical signals, effectively suppresses electrical interference, and greatly improves the response speed and comprehensive anti-interference ability.

[0030] To visually judge faults and facilitate debugging, light-emitting diodes of different colors are connected in the main path of the circuit to facilitate the monitoring of the in-use state and subsequent operation and maintenance guarantee work.

[0031] In this circuit, in order to adapt to the characteristics of different service types, a switch is specifically set to turn on or off the high-voltage start-stop function. For services such as ARQ (Automatic Repeat-reQuest) or FEC (Forward Error Correction), there is a continuous idle signal input, and it is not necessary to frequently turn on or off the high voltage. For services such as DSC (Digital Selective Calling), NAVTEX (Navigation Warning Telex), SSB (Synchronous Signal), and weather facsimile, which are broadcast irregularly or intermittently, there is no idle signal during non-broadcast periods. In order to reduce the misoperation rate of manually turning on and off the high voltage, a high-voltage start-stop circuit can be introduced to process the engine room requirements in a timely and accurate manner.

[0032] Circuit waveform monitoring

[0033] According to the characteristics of the KEY&PTT and PA ON control circuits, when an audio signal is input, the waveform is as shown in TP1. This waveform does not reflect the trend of the amplitude decreasing at the beginning and end stages of the audio signal, and does not affect circuit analysis. For the KEY&PTT start-stop power amplifier function, the audio (AF) signal is input to pin 1 of U2, and the output is the TP9 (XMT) waveform. At the beginning stage of the audio (AF) signal, a high-level to low-level conversion is achieved to control the transceiver to turn on the power amplifier output power; at the end stage of the audio (AF) signal, a low-level to high-level conversion is achieved to control the transceiver to stop the power amplifier output power. For the high-voltage switch function, the audio (AF) signal is input to pin 1 of U1, and the waveform output from pin 6 of U1 is like TP2, with a high-level to low-level setting. At this time The pin is connected to 5V and a pull-up resistor, and is in a high-level state, that is, pin 3 of U5A is set to high level and pin 11 of U5B is set to low level. U5A is in a working state and U5B is in a low-level reset state. Therefore, after the signal from pin 6 of U1 is input to pin 1 of U5A, a short pulse signal like the TP6 waveform is output from pin 13, controlling the optocoupler U6 to act, and then generating a 5V short pulse voltage signal, which is input to the corresponding pin of the PA ON button on the exciter switch panel to achieve the high-voltage turn-on function. After the audio (AF) signal is input to U1, a pulse signal like the TP3 waveform is simultaneously output from pin 7, achieving a conversion from low level to high level. At the end stage of the audio (AF) signal, the level is set from high level to low level, and after being optimized by a differentiating circuit, a short low-level pulse is generated and input to the 555 timer U3 module, and a long-duration pulse signal like TP5 is output from pin 7 of U3. At this time, it is in the state of turning on the high voltage, The foot is set to low level from the exciter end. After entering the input circuit, the 3rd pin of U5A is set to low level and the 11th pin of U5B is set to high level, enabling U5A to be in the low-level reset state and U5B to be in the working state. At the end stage of the long-duration pulse signal, the conversion from high level to low level is achieved and input to the 9th pin of U5B, and a short pulse signal such as TP7 is output from the 5th pin, controlling the operation of the optocoupler U7, thereby generating a 5V short-pulse voltage signal and inputting it to the corresponding pin of the PA ON button on the exciter switch panel to achieve the function of turning off the high voltage. The TP8 waveform is a combination of the TP6 and TP7 waveforms, vividly showing the time node of the short voltage pulse for switching the high voltage and the waveform characteristics. The digital module has the characteristics of high integration, perfect functions, accurate parameters, sensitive and rapid response of waveform parameters, little temperature drift and stable operation, and can effectively meet and improve the need for transmitting the audio (AF) signal of the transmitter. The signal waveforms of the KEY&PTT and PA ON control circuits are shown in Figure 3 。

[0034] Wiring method

[0035] For the start-stop power amplifier part of this circuit, it is necessary to conveniently connect the audio (AF) signal and lead out the Key (XMT) signal, and take power and ground at appropriate positions; for the switch high-voltage part, the electrical pulses for turning on and off the high voltage output from the optocoupler need to be sent to the corresponding pins of the PA ON high-voltage switch of the exciter, and the high and low voltage level values before and after applying the high voltage need to enter the board, cooperating with the inverter to control the operation of part A or B of the U5 chip (before applying the high voltage, U5A works and U5B is in the low-level reset state, ready to control turning on the high voltage at any time; after applying the high voltage, U5A is in the low-level reset state and U5B works, ready to control turning off the high voltage at any time). At the same time, the 19th pin of TB3 needs to be connected to the 20th pin to ground so that the 9th pin can normally feedback the change state of the working level. Considering aesthetics, dust prevention and moisture protection, it is required that the designed circuit is small and easy to install, and can be fault-diagnosed in time and replaced conveniently when a fault occurs. It is selected to be installed in the terminal interface unit at the lower rear part of the machine and fixed on the inner wall of the unit box by insulating columns to meet the basic conditions for the circuit to work.

[0036] This designed circuit has six wiring terminals, namely power supply (5VDC), ground (GND), audio signal input (AF), KEY key control output signal (XMT SW), PA ON switch high-voltage electrical pulse output signal (PA PWR SW), and switch high-voltage state level input signal (PA ON), which are respectively connected to the corresponding wiring ports of the terminal interface unit TB2, TB3, J411 and the PA ON switch button of the exciter. The specific wiring information is shown in Table 1. The definition of the wiring ports of the terminal interface unit is shown in Table 2. The definition of the wiring ports of the exciter switch panel is shown in Table 3.

[0037]

[0038] Table 1 Wiring Table of KEY&PTT and PA ON Control Circuit

[0039]

[0040] Table 2 Wiring Port Table of Terminal Interface Unit

[0041]

[0042] Table 3 Wiring Port Table of Exciter Switch Panel

[0043] 3.5 Circuit Benefit Calculation

[0044] According to the main power amplifier situation of the power amplification stage of the corresponding transmitter in this project, there are 20 power amplifier modules in the main power amplifier stage of the 10kW transmitter and 10 power amplifier modules in the main power amplifier stage of the 5kW transmitter; according to the static current value of 4A / power amplifier module and the high voltage of the power amplifier circuit of 80VDC for the transmitters of the 7-series models (JRS-714, JRS-753) of this brand, and the static current value of 2A / power amplifier module and the high voltage of the power amplifier circuit of 110VDC for the transmitters of the 9-series models (JRS-914, JRS-953) of this brand, and calculated based on each machine working 12 hours a day and standby for 12 hours, the energy-saving calculation values are shown in Table 3. According to the estimation of long-term energy-saving benefits, the annual power savings of a 5kW JRS953-type transmitter exceed 10,000 kWh, and the annual power savings of a 10kW JRS914-type transmitter exceed 20,000 kWh.

[0045] The energy-saving efficiency of the predictable design project operation is obvious.

[0046]

[0047] Table 4 Energy-saving Calculation Table of KEY&PTT and PA ON Control Circuit

[0048] The main JRC transmitter after the overall transformation of Guangzhou Coast Radio Station. This part of the transmitter covers all types of transmission services in the center. Among them, some types of services have the characteristics of irregular or intermittent broadcasting, and there is no idle signal during non-broadcasting periods. At present, the signals sent from the central control system of the center to the transmitter station do not have independent control signals for switching high voltage and starting and stopping the power amplifier. The high voltage of the transmitter must be kept on all the time to ensure that the transmitter can transmit normally when there is a service signal. This article explores the use of digital methods to upgrade the existing PTT&KEY signal conversion circuit in the JRC short-wave transmitter, and integrates and adds a high-voltage switch control circuit to effectively achieve the purpose of reducing energy consumption, reducing noise, reducing hardware damage and the risk of human misoperation, improving the overall operation quality of the transmitter, and enhancing the signal transmission guarantee ability.

Claims

1. A power amplifier circuit for starting and stopping a transmitter switch, characterized in that: Electrically connected to the audio signal, including a level sensor chip. The 1st pin of the level sensor chip serves as the signal input terminal and is connected to the audio signal through capacitor C2. The 2nd pin of the level sensor chip is connected to the 3rd pin of the level sensor chip through adjustable resistor VR2. The 3rd pin of the level sensor chip is grounded through capacitor C4. The 4th pin of the level sensor chip is grounded. The 5th pin of the level sensor chip is grounded through capacitor C6. The 6th pin of the level sensor chip serves as the signal output terminal; The model of the level sensor chip is NJM2072; The 6th pin of the level sensor chip is connected to the 2nd pin of board J1 on one hand. On the other hand, the 6th pin of the level sensor chip is sequentially connected to light-emitting diode D6, light-emitting diode D5, and resistor R3. The other end of resistor R3 is connected to the 6th pin of board J1. The 1st pin of board J1 is grounded. The 3rd pin is respectively connected to capacitor C2 and the signal input terminal of the switching high-voltage circuit. The 4th pin is connected to the high-low voltage inverting input terminal of the switching high-voltage circuit. The 5th pin is connected to the signal output terminal of the switching high-voltage circuit. The 3rd pin of board J1 outputs the audio signal; Board J1 is a PTT board and includes 6 pins. The 1st pin - 6th pin of board J1 respectively serve as ports of GND, XMT SW, AF-In, PA ON, PA PWR SW, 5VDC. The above 1st pin - 6th pin of board J1 correspond to: ground, KEY key control output signal, audio signal input, switching high-voltage state level input signal, PA ON switching high-voltage pulse output signal, power supply in sequence.

2. The power amplifier circuit for starting and stopping the transmitter switch according to claim 1, characterized in that: Light-emitting diode D5 is a yellow light-emitting diode.

3. The transmitter switch start-stop power amplifier circuit according to claim 2, wherein: Capacitor C6 is a polarized capacitor.

4. The transmitter switch start-stop power amplifier circuit according to claim 3, wherein: The nominal value of adjustable resistor VR2 is 100KΩ.

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