Signal transmission system and control method thereof

Abstract

The invention discloses a signal transmission system and a control method thereof, and relates to the technical field of signal transmission. The signal transmission system comprises a coupling module, a first switch module, a second switch module, a third switch module, a low-frequency signal processing module, a signal composite module, a signal conversion module, an electro-optical conversion module, a photoelectric conversion module, an amplification module, a voltage source and a controller. When the voltage source is connected with the first end of the low-frequency signal processing module, the third end of the low-frequency signal processing module is connected with the third end of the signal composite module, and the first power source is disconnected with the fourth end of the signal composite module, the controller calibrates the amplification factor of the amplification module so as to calibrate the gain of the signal transmission system. And the offset voltage of the amplification module is calibrated to calibrate the zero point of the second voltage output by the amplification module. Through the above mode, the gain of the system and the zero point of the output voltage can be calibrated.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of signal transmission technology, and in particular, to a signal transmission system and a control method thereof. Background Art

[0002] At present, the optical fiber signal transmission system usually consists of three parts. These three parts include the transmitter that converts electrical signals into optical signals, the analog optical fiber that connects the transmitter and the receiver to transmit the optical signal, and the receiver that converts the optical signal into electrical signals. The advantage of using analog optical fiber to transmit signals is that it has strong anti-interference performance and can withstand very high voltages.

[0003] However, during the operation of the optical fiber signal transmission system, the gain of the system and the zero point of the output voltage may be inaccurate due to anomalies such as temperature drift, which in turn leads to poor transmission accuracy of the system. Summary of the invention

[0004] The embodiment of the present application provides a signal transmission system and a control method thereof, which can calibrate the gain of the system and the zero point of the output voltage.

[0005] In a first aspect, an embodiment of the present application provides a signal transmission system, including:

[0006] Coupling module, first switch module, second switch module, third switch module, low-frequency signal processing module, signal compound module, signal conversion module, electro-optical conversion module, photoelectric conversion module, amplification module, voltage source and controller;

[0007] The first end of the coupling module is connected to the input signal and the second end of the first switch module respectively, the second end of the coupling module is connected to the first end of the signal compound module, the second end of the signal compound module is connected to the second end of the second switch module, the third end of the signal compound module is connected to the first end of the signal conversion module and the third end of the second switch module respectively, the fourth end of the signal compound module is connected to the first end of the third switch module, the second end of the third switch module is connected to the first power supply, the first end of the second switch module is connected to the third end of the low-frequency signal processing module, the first end of the low-frequency signal processing module is connected to the first end of the first switch module, the third end of the first switch module is connected to the voltage source, the second end of the signal conversion module is connected to the first end of the electro-optical conversion module, the third end of the signal conversion module is connected to the second end of the low-frequency signal processing module, the photoelectric conversion module is connected to the amplification module, and the first switch module, the second switch module, the third switch module, the voltage source and the amplification module are all connected to the controller;

[0008] The coupling module is used to couple the high-frequency signal in the input signal to the first end of the signal compound module;

[0009] The voltage source is used to output a calibration voltage, and the magnitude of the calibration voltage is determined by the controller;

[0010] The first switch module is used to be controlled by the controller to establish a connection between the input signal and the first end of the low-frequency signal processing module, or to establish a connection between the voltage source and the first end of the low-frequency signal processing module;

[0011] The low-frequency signal processing module is used to amplify the difference between the low-frequency signal in the input signal or the calibration voltage and the low-frequency signal in the feedback signal output by the signal conversion module, and output a low-frequency error signal;

[0012] The second switch module is used to be controlled by the controller to establish a connection between the third end of the low-frequency signal processing module and the second end of the signal compound module, or to establish a connection between the third end of the low-frequency signal processing module and the third end of the signal compound module;

[0013] The third switch module is used to be controlled by the controller to establish or disconnect the connection between the first power source and the fourth end of the signal combination module;

[0014] The signal compound module is used to output a composite signal obtained by superimposing the high-frequency signal and the low-frequency error signal to the signal conversion module when the first power supply is connected to the signal compound module, and stop outputting the composite signal when the first power supply is disconnected from the signal compound module;

[0015] The signal conversion module is used to output a driving current for driving the electro-optical conversion module which has a linear relationship with the composite signal, and is used to generate the feedback signal based on the driving current;

[0016] The electro-optical conversion module is used to output an optical signal corresponding to the driving current, wherein the optical signal is transmitted through an analog optical fiber;

[0017] The photoelectric conversion module is used to receive the optical signal from the analog optical fiber and output a first voltage corresponding to the optical signal;

[0018] The amplification module is used to amplify the first voltage and then output a second voltage;

[0019] The controller is used to calibrate the amplification factor of the amplification module to calibrate the gain of the signal transmission system, and calibrate the offset voltage of the amplification module to calibrate the zero point of the second voltage when the voltage source is connected to the first end of the low-frequency signal processing module, the third end of the low-frequency signal processing module is connected to the third end of the signal compound module, and the first power supply is disconnected from the fourth end of the signal compound module.

[0020] In one or more embodiments, the coupling module includes a first capacitor;

[0021] The first end of the first capacitor is connected to the input signal, and the second end of the first capacitor is connected to the first end of the signal combining module.

[0022] In one or more embodiments, the first switch module includes a first single-pole double-throw switch, the second switch module includes a second single-pole double-throw switch, and the third switch module includes a controllable switch;

[0023] The common end of the first single-pole double-throw switch is the first end of the first switch module, the first connection end of the first single-pole double-throw switch is the second end of the first switch module, and the second connection end of the first single-pole double-throw switch is the third end of the first switch module;

[0024] The common end of the second single-pole double-throw switch is the first end of the second switch module, the first connection end of the second single-pole double-throw switch is the second end of the second switch module, and the second connection end of the second single-pole double-throw switch is the third end of the second switch module;

[0025] The controllable switch is connected between the first power supply and the fourth terminal of the signal combining module;

[0026] Wherein, the control end of the first single-pole double-throw switch, the control end of the second single-pole double-throw switch and the control end of the controllable switch are all connected to the controller.

[0027] In one or more embodiments, the low-frequency signal processing module includes a first resistor, a second resistor, a second capacitor and a first operational amplifier, and the signal compounding module includes a third resistor and a buffer amplifier;

[0028] The first end of the first resistor is respectively connected to the output end of the first operational amplifier and the first end of the second switch module, the second end of the first resistor is respectively connected to the first end of the second capacitor and the first end of the second resistor, the second end of the second resistor is grounded, the second end of the second capacitor is respectively connected to the second input end of the first operational amplifier and the third end of the signal conversion module, and the first input end of the first operational amplifier is connected to the first end of the first switch module;

[0029] The first end of the third resistor is connected to the second end of the second switch module, the second end of the third resistor is respectively connected to the input end of the buffer amplifier and the second end of the coupling module, and the output end of the buffer amplifier is respectively connected to the first end of the signal conversion module and the third end of the second switch module.

[0030] In one or more embodiments, the low-frequency signal processing module includes a second operational amplifier, and the signal compounding module includes a compound amplifier;

[0031] The first input terminal of the second operational amplifier is connected to the first terminal of the first switch module, the second input terminal of the second operational amplifier is connected to the third terminal of the signal conversion module, and the output terminal of the second operational amplifier is connected to the first terminal of the second switch module;

[0032] The first input end of the composite amplifier is connected to the second end of the coupling module, the second input end of the composite amplifier is connected to the second end of the second switch module, and the output end of the composite amplifier is connected to the third end of the second switch module.

[0033] In one or more embodiments, the signal conversion module includes a power transistor and a fourth resistor;

[0034] The base of the power transistor is connected to the third end of the signal compound module, the collector of the power transistor is connected to the first end of the electro-optical conversion module, and the emitter of the power transistor is respectively connected to the first end of the fourth resistor and the second end of the low-frequency signal processing module.

[0035] In one or more embodiments, the signal transmission system further includes a first isolation resistor and a second isolation resistor;

[0036] The first isolation resistor is connected between the input signal and the second end of the first switch module, and the second isolation resistor is connected between the third end of the signal combination module and the third end of the second switch module.

[0037] In a second aspect, an embodiment of the present application provides a control method based on the signal transmission system as described above, the method comprising:

[0038] Controlling the first switch module to establish a connection between the voltage source and the first end of the low-frequency signal processing module, controlling the second switch module to establish a connection between the third end of the low-frequency signal processing module and the third end of the signal compound module, and controlling the third switch module to disconnect the connection between the first power source and the fourth end of the signal compound module;

[0039] Based on the calibration voltage output by the voltage source and the second voltage output by the amplifying module, the amplification factor of the amplifying module is calibrated to calibrate the gain of the signal transmission system, and the offset voltage of the amplifying module is calibrated to calibrate the zero point of the second voltage.

[0040] In one or more embodiments, based on the calibration voltage output by the voltage source and the second voltage output by the amplification module, calibrating the amplification factor of the amplification module to calibrate the gain of the signal transmission system, and calibrating the offset voltage of the amplification module to calibrate the zero point of the second voltage includes:

[0041] When the calibration voltage is 0V, calibrating the offset voltage of the amplification module so that the second voltage is 0V;

[0042] When the calibration voltage is not 0V, the amplification factor of the amplification module is calibrated so that the ratio of the second voltage to the calibration voltage is a preset gain.

[0043] In one or more embodiments, after calibrating the amplification factor of the amplification module to calibrate the gain of the signal transmission system based on the calibration voltage output by the voltage source and the second voltage output by the amplification module, and calibrating the offset voltage of the amplification module to calibrate the zero point of the second voltage, the method further includes:

[0044] The first switch module is controlled to establish a connection between the input signal and the first end of the low-frequency signal processing module, the second switch module is controlled to establish a connection between the third end of the low-frequency signal processing module and the second end of the signal compound module, and the third switch module is controlled to establish a connection between the first power supply and the fourth end of the signal compound module.

[0045] The beneficial effects of the present application are as follows: the signal transmission system of the embodiment of the present application includes a coupling module, a first switch module, a second switch module, a third switch module, a low-frequency signal processing module, a signal compound module, a signal conversion module, an electro-optical conversion module, a photoelectric conversion module, an amplification module, a voltage source and a controller. Among them, the coupling module couples the high-frequency signal in the input signal to the first end of the signal compound module; the voltage source outputs a calibration voltage; the first switch module is controlled by the controller to establish a connection between the input signal and the first end of the low-frequency signal processing module, or to establish a connection between the voltage source and the first end of the low-frequency signal processing module; the low-frequency signal processing module amplifies the difference between the low-frequency signal in the input signal or the calibration voltage and the low-frequency signal in the feedback signal output by the signal conversion module, and outputs a low-frequency error signal; the second switch module is controlled by the controller to establish a connection between the third end of the low-frequency signal processing module and the second end of the signal compound module, or to establish a connection between the third end of the low-frequency signal processing module and the third end of the signal compound module; the third switch module The block is controlled by the controller to establish or disconnect the connection between the first power supply and the fourth end of the signal compound module; the signal compound module outputs a composite signal of the high-frequency signal and the low-frequency error signal superimposed to the signal conversion module when the first power supply is connected to the signal compound module, and stops outputting the composite signal when the first power supply is disconnected from the signal compound module; the signal conversion module outputs a driving current for driving the electro-optical conversion module that is linearly related to the composite signal, and is used to generate a feedback signal based on the driving current; the electro-optical conversion module outputs an optical signal corresponding to the driving current, wherein the optical signal is transmitted through an analog optical fiber; the optoelectronic conversion module receives the optical signal from the analog optical fiber, and outputs a first voltage corresponding to the optical signal; the amplification module amplifies the first voltage and outputs a second voltage. Through the above method, the low-frequency signal and the high-frequency signal in the input signal are processed separately. At the same time, the controller controls the first switch module to connect the voltage source to the first end of the low-frequency signal processing module, controls the second switch module to connect the third end of the low-frequency signal processing module to the third end of the signal compound module, and controls the third switch module to disconnect the first power source from the fourth end of the signal compound module. At this time, the channel for processing the low-frequency signal is running, while the channel for processing the high-frequency signal is stopped. Then, the gain of the signal transmission system can be calibrated by calibrating the amplification factor of the amplification module, and the zero point of the second voltage can be calibrated by calibrating the offset voltage of the amplification module. Thus, the gain of the system and the zero point of the output voltage are calibrated. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] One or more embodiments are exemplarily described by the figures in the corresponding drawings, and these exemplary descriptions are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0047] Figure 1 is a schematic diagram of a component block diagram of a signal transmission system provided in an embodiment of the present application;

[0048] Figure 2 The circuit structure of the signal transmission system provided in the embodiment of the present application is shown in FIG. Figure 1 ;

[0049] Figure 3 The circuit structure of the signal transmission system provided in the embodiment of the present application is shown in FIG. Figure 2 ;

[0050] Figure 4 is a flow chart of a control method based on a signal transmission system provided in an embodiment of the present application;

[0051] Figure 5 The embodiment of this application provides Figure 4 A schematic diagram of an implementation of step 402 is shown in FIG. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and in detail in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0053] It should be noted that, when an element is described as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may exist therebetween.

[0054] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no structural conflict between them.

[0055] Please refer to Figure 1 , Figure 1 Schematic diagram of a block diagram of a signal transmission system provided in an embodiment of the present application. Figure 1 As shown, the signal transmission system 1000 includes a coupling module 10, a first switch module 20, a second switch module 30, a third switch module 40, a low-frequency signal processing module 50, a signal compound module 60, a signal conversion module 70, an electro-optical conversion module 80, a photoelectric conversion module 90, an amplification module 100, a voltage source 110 and a controller 120.

[0056] The first end of the coupling module 10 is connected to the input signal VI N and the second end of the first switch module 20 at the first node P1, the second end of the coupling module 10 is connected to the first end of the signal compound module 60, the second end of the signal compound module 60 is connected to the second end of the second switch module 30, the third end of the signal compound module 60 is connected to the first end of the signal conversion module 70 and the third end of the second switch module 30, the fourth end of the signal compound module 60 is connected to the first end of the third switch module 40, the second end of the third switch module 40 is connected to the first power supply VC1, and the first end of the second switch module 30 is connected to the low-frequency signal processing module 70. The third end of the module 50 is connected, the first end of the low-frequency signal processing module 50 is connected to the first end of the first switch module 20, the third end of the first switch module 20 is connected to the voltage source 110, the second end of the signal conversion module 70 is connected to the first end of the electro-optical conversion module 80, the third end of the signal conversion module 70 is connected to the second end of the low-frequency signal processing module 50, the photoelectric conversion module 90 is connected to the amplification module 100, and the first switch module 20, the second switch module 30, the third switch module 40, the voltage source 110 and the amplification module 100 are all connected to the controller 120.

[0057] Specifically, the coupling module 10 is used to couple the high-frequency signal in the input signal VIN (which is a DC signal) to the first end of the signal compound module 60. The voltage source 110 is used to output the calibration voltage VRE, and the magnitude of the calibration voltage VRE is determined by the controller 120, that is, the controller 120 can control the magnitude of the calibration voltage VRE by controlling the voltage source 110. The first switch module 20 is used to be controlled by the controller 120 to establish a connection between the input signal VIN and the first end of the low-frequency signal processing module 50, or the first switch module 20 is used to be controlled by the controller 120 to establish a connection between the voltage source 110 and the first end of the low-frequency signal processing module 50. The low-frequency signal processing module 50 is used to amplify the difference between the low-frequency signal in the input signal VIN or the calibration voltage VRE and the low-frequency signal in the feedback signal output by the signal conversion module 70, and output a low-frequency error signal. Wherein, if the first switch module 20 is used to be controlled by the controller 120 to establish a connection between the input signal VIN and the first end of the low-frequency signal processing module 50, the low-frequency signal processing module 50 is used to amplify the difference between the low-frequency signal in the input signal VIN and the low-frequency signal in the feedback signal output by the signal conversion module 70, and output a low-frequency error signal; if the first switch module 20 is used to be controlled by the controller 120 to establish a connection between the voltage source 110 and the first end of the low-frequency signal processing module 50, the low-frequency signal processing module 50 is used to amplify the difference between the low-frequency signal in the calibration voltage VRE and the low-frequency signal in the feedback signal output by the signal conversion module 70, and output a low-frequency error signal. The second switch module 30 is used to be controlled by the controller 120 to establish a connection between the third end of the low-frequency signal processing module 50 and the second end of the signal compound module 60, or the second switch module 30 is used to be controlled by the controller 120 to establish a connection between the third end of the low-frequency signal processing module 50 and the third end of the signal compound module 60. The third switch module 40 is used to establish or disconnect the connection between the first power supply VC1 and the fourth end of the signal compound module 60 under the control of the controller 120. The signal compound module 60 is used to output a composite signal obtained by superimposing a high-frequency signal and a low-frequency error signal to the signal conversion module 70 when the first power supply VC1 is connected to the signal compound module 60, and stop outputting the composite signal when the first power supply VC1 is disconnected from the signal compound module 70. The signal conversion module 70 is used to output a driving current for driving the electro-optical conversion module 80 that is linearly related to the composite signal, and is used to generate a feedback signal based on the driving current. The electro-optical conversion module 80 is used to output an optical signal corresponding to the driving current, wherein the optical signal is transmitted through the analog optical fiber 2000. The photoelectric conversion module 90 is used to receive an optical signal from the analog optical fiber 2000, and output a first voltage V1 corresponding to the optical signal. The amplification module 100 is used to amplify the first voltage V1 and output a second voltage V2.The controller 120 is used to calibrate the amplification factor of the amplifier module 100 to calibrate the gain of the signal transmission system 1000, and calibrate the offset voltage of the amplifier module 100 to calibrate the zero point of the second voltage V2 when the voltage source 110 is connected to the first end of the low-frequency signal processing module 50, the third end of the low-frequency signal processing module 50 is connected to the third end of the signal compound module 60, and the first power source VC1 is disconnected from the fourth end of the signal compound module 60. In the embodiment of the present application, the corresponding relationship between the two variables (such as the corresponding relationship between the optical signal and the driving current) means that the two variables have a linear relationship (that is, there is a first-order function relationship between the two variables), such as a proportional relationship.

[0058] In this embodiment, when the controller 120 controls the first switch module 20 to establish a connection between the voltage source 110 and the first end of the low-frequency signal processing module 50, and controls the second switch module 30 to establish a connection between the third end of the low-frequency signal processing module 50 and the third end of the signal compound module 60, and controls the third switch module 40 to disconnect the connection between the first power supply VC1 and the fourth end of the signal compound module 60, the channel for transmitting high-frequency signals (including the channel where the coupling module 10 is located) stops running, while the channel for transmitting low-frequency signals (including the channel where the low-frequency signal processing module 50 is connected) keeps running, and, since the connection between the signal compound module 60 and the first power supply VC1 is disconnected, the signal compound module 60 loses power and cannot run, and only the low-frequency signal is input to the signal conversion module 70, so that the second voltage V2 finally obtained is also only the low-frequency signal. At this time, only the channel for transmitting low-frequency signals is running in the signal transmission system 1000.

[0059] Thus, the gain of the signal transmission system 1000 is the gain of the channel for transmitting low-frequency signals, which is V2 / VRE. This gain is related to the gain of the amplifier module 100, and then the controller 120 can calibrate the gain of the amplifier module 100 so that V2 / VRE is equal to the preset gain, thereby achieving the purpose of calibrating the gain of the signal transmission system 1000. Among them, the preset gain is a pre-set gain, which can be set based on the actual application scenario, and the embodiments of the present application do not impose specific restrictions on this. For example, in one embodiment, assuming that the preset gain is 1, under the premise that VRE remains unchanged, the controller 120 calibrates the gain of the amplifier module 100 so that V2=VRE, and thus V2 / VRE=1, thereby realizing the calibration process of the gain.

[0060] It can be understood that, in the signal transmission system 100 of the present application, the gain of the channel transmitting the low-frequency signal is equal to the gain of the channel transmitting the high-frequency signal, and is also equal to the gain of the low-frequency signal and the high-frequency signal transmitted simultaneously, that is, equal to the gain of the signal transmission system 100 transmitting the input signal VIN. Then, by calibrating the gain of the channel transmitting the low-frequency signal, the calibration of the gain of the signal transmission system 100 transmitting the input signal VIN is actually completed, so that the accuracy of the gain of the signal transmission system 100 can be improved, which is conducive to improving the transmission accuracy of the signal transmission system 1000.

[0061] Secondly, the zero point of the second voltage V2 is related to the offset voltage of the amplifying module 100, so the controller 120 can calibrate the offset voltage of the amplifying module 100 so that when the calibration voltage VRE is 0, the output end of the amplifying module 100 is zero (that is, the second voltage V2 is 0), thereby achieving the purpose of calibrating the zero point of the second voltage V2. In this case, when the signal transmission system 100 is used to transmit the input signal VIN (including high-frequency signals and low-frequency signals), if the voltage of the input signal VIN is zero, the second voltage V2 is also 0. Among them, the offset voltage (Offset Vo ltage) refers to the difference between the actual output voltage observed at the output end and the ideal zero voltage when there is no signal or the signal is zero at the input end of the amplifying module 100. This phenomenon is usually caused by the inability to make all the components inside the amplifying module 100 completely symmetrical during the manufacturing process. In addition, in the embodiment of the present application, calibrating the zero point of the second voltage V2 means that it is ultimately necessary to ensure that when there is no input signal VIN or the voltage of the input signal VIN is 0, the second voltage V2 is also 0.

[0062] It can be understood that in the signal transmission system 100 of the present application, since there is no zero point in the high-frequency signal, after the zero point calibration of the second voltage V2 is completed through the channel for transmitting the low-frequency signal, when the high-frequency signal and the low-frequency signal are transmitted at the same time, the zero point of the second voltage V2 is also assumed to have been calibrated, which is beneficial to improve the transmission accuracy of the signal transmission system 1000.

[0063] In addition, since each switch module (including the first switch module 20, the second switch module 30 and the third switch module 40) in the embodiment of the present application is not provided between the input signal VIN and the first node P1, it is possible to select a usable switch device in practical applications. On the contrary, if a switch device is provided between the input signal VIN and the first node P1, then because all signals must pass through the switch device, the input capacitance and bandwidth of the switch device are the input capacitance and bandwidth of the entire signal transmission system. In this case, if the bandwidth required to be achieved by the signal transmission system is relatively low, such as a bandwidth required to be achieved of less than 100MHz, then a usable switching device can still be selected in practical applications; however, if the bandwidth required to be achieved by the signal transmission system is relatively high, such as a bandwidth required to be achieved of DC-2GHz (i.e., from a DC signal to a high-frequency signal with a frequency of 2GHz), then in this case, since the switching device must also be able to reach a frequency of 2GHz, a usable switching device cannot be selected in practical applications. This is because the switching devices in practical applications usually only reach a maximum of about 500MHz, such as an electronic switch of model MAX4564, and although there are radio frequency electronic switches with a frequency of up to 20GHz, the input of the radio frequency electronic switch must be an AC signal, and the input signal VI N of the present application must be a DC signal, so the radio frequency electronic switch cannot be used. It can be seen from this that if a switching device is provided between the input signal VI N and the first node P1, then it can only be used in low-bandwidth application scenarios. In the embodiment of the present application, since each switch module is not provided between the input signal VIN and the first node P1, it is possible to select usable switch devices in practical applications and it can be applied to high-bandwidth application scenarios, thus having strong practicality.

[0064] After the gain and the zero point calibration of the signal transmission system 1000 are completed, the controller 120 controls the first switch module 20 to establish a connection between the input signal VI N and the first end of the low-frequency signal processing module 50, and controls the second switch module 30 to establish a connection between the second end of the low-frequency signal processing module 50 and the third end of the signal compound module 60, and controls the third switch module 40 to establish a connection between the first power supply VC1 and the fourth end of the signal compound module 60. Subsequently, the signal transmission system 100 can be used to transmit the input signal VI N with high transmission accuracy.

[0065] Please refer to Figure 2 , Figure 2 A circuit structure of a signal transmission system is shown as an example. Figure 2 As shown, the coupling module 10 includes a first capacitor C1.

[0066] The first end of the first capacitor C1 is connected to the input signal VIN, and the second end of the first capacitor C1 is connected to the first end of the signal combining module 60 .

[0067] In this embodiment, the first switch module 20 includes a first single-pole double-throw switch K1 , the second switch module 30 includes a second single-pole double-throw switch K2 , and the third switch module 40 includes a controllable switch K3 .

[0068] The common end of the first single-pole double-throw switch K1 is the first end of the first switch module 20 (connected to the non-inverting input end of the first operational amplifier UA1 in this embodiment), the first connection end of the first single-pole double-throw switch K1 is the second end of the first switch module 20 (connected to the first coupling resistor RA1 in this embodiment), and the second connection end of the first single-pole double-throw switch K1 is the third end of the first switch module 20 (connected to the voltage source 110 in this embodiment). The common end of the second single-pole double-throw switch K2 is the first end of the second switch module 30 (connected to the output end of the first operational amplifier UA1 in this embodiment), the first connection end of the second single-pole double-throw switch K2 is the second end of the second switch module 30 (connected to the third resistor R3 in this embodiment), and the second connection end of the second single-pole double-throw switch K2 is the third end of the second switch module 30 (connected to the second coupling resistor RA2 in this embodiment). The controllable switch K3 is connected between the first power supply VC1 and the fourth end of the signal combination module 60.

[0069] The control end of the first single-pole double-throw switch K1 , the control end of the second single-pole double-throw switch K2 , and the control end of the controllable switch K3 are all connected to the controller 120 .

[0070] Among them, in the embodiment of the present application, only one implementation of the switches in the first switch module 20, the second switch module 30 and the third switch module 40 is exemplarily shown. In other embodiments, the switches in the first switch module 20, the second switch module 30 and the third switch module 40 can be any controllable switches, such as relays, triodes, insulated gate bipolar transistor (IGBT) devices, MOS controlled thyristor (MCT) devices, etc. And the switches in the first switch module 20, the second switch module 30 and the third switch module 40 can be implemented by one switch, or by a plurality of switches connected in series and / or in parallel.

[0071] In this embodiment, the low-frequency signal processing module 50 includes a first resistor R1, a second resistor R2, a second capacitor C2 and a first operational amplifier UA1, and the signal combining module 60 includes a third resistor R3 and a buffer amplifier UB1.

[0072] Among them, the first end of the first resistor R1 is connected to the output end of the first operational amplifier UA1 and the first end of the second switch module 30 respectively, the second end of the first resistor R1 is connected to the first end of the second capacitor C2 and the first end of the second resistor R2 respectively, the second end of the second resistor R2 is grounded, the second end of the second capacitor C2 is connected to the second input end of the first operational amplifier UA1 and the third end of the signal conversion module 70 respectively, and the first input end of the first operational amplifier UA1 is connected to the first end of the first switch module 20. The first end of the third resistor R3 is connected to the second end of the second switch module 30, the second end of the third resistor R3 is connected to the input end of the buffer amplifier UB1 and the second end of the coupling module 10 respectively, and the output end of the buffer amplifier UB1 is connected to the first end of the signal conversion module 70.

[0073] In this embodiment, the signal conversion module 70 includes a power transistor Q1 and a fourth resistor R4 .

[0074] Among them, the base of the power transistor Q1 is connected to the third end of the signal combination module 60, the collector of the power transistor Q1 is connected to the first end of the electro-optical conversion module 80, and the emitter of the power transistor Q1 is connected to the first end of the fourth resistor R4 and the second end of the low-frequency signal processing module 50 respectively.

[0075] In this embodiment, the electro-optical conversion module 80 includes a laser diode D1 .

[0076] The first end of the laser diode D1 is connected to the positive power supply V+, and the second end of the laser diode D1 is connected to the third end of the first switch tube Q1.

[0077] Specifically, the laser diode D1 is a semiconductor laser, also known as LD (Laser Diode). It uses semiconductor materials to generate and amplify laser beams. The working principle of the laser diode D1 is to inject current into the semiconductor material to generate stimulated radiation and amplify it into laser (i.e. output light signal).

[0078] In this embodiment, the photoelectric conversion module 90 includes a photodiode D2, and the amplification module 100 includes an amplifier UC1, wherein the cathode of the photodiode D2 is connected to a positive power supply V+, and the input end of the amplifier UC1 is connected to the anode of the photodiode D2.

[0079] Specifically, the photodiode D2 is used to receive an optical signal from the simulated optical fiber 2000 and convert the optical signal into a first voltage V1. The amplifier UC1 is used to amplify the first voltage V2 and output a second voltage V2.

[0080] In this embodiment, the signal transmission system 100 further includes a first isolation resistor RA1 and a second isolation resistor RA2 .

[0081] The first isolation resistor RA1 is connected between the input signal VIN and the second end of the first switch module 20 , and the second isolation resistor RA2 is connected between the third end of the signal combining module 60 and the third end of the second switch module 30 .

[0082] The first isolation resistor RA1 and the second isolation resistor RA2 can prevent the low-frequency input capacitance of the first SPDT switch K1 and the second SPDT switch K2 from adversely affecting the bandwidth of the channel for transmitting high-frequency signals (i.e., the channel where the first capacitor C1, the buffer amplifier UB1 and the power transistor Q1 are located).

[0083] The following Figure 2 The principle of the circuit structure shown is explained.

[0084] When the controller 120 controls the common terminal of the first single-pole double-throw switch K1 to be connected to the second connection terminal (i.e., the voltage source 110 is connected to the in-phase input terminal of the first operational amplifier UA1), and controls the common terminal of the second single-pole double-throw switch K2 to be connected to the second connection terminal of the second single-pole double-throw switch K2 (i.e., the output terminal of the first operational amplifier UA1 is connected to the second isolation resistor RA2), and controls the controllable switch K3 to be disconnected (i.e., the connection between the first power supply VC1 and the buffer amplifier UB1 is disconnected, and the output of the buffer amplifier UB1 is in a high impedance state), the channel for transmitting high-frequency signals (including the channel where the first capacitor C1 is located) stops operating, while the channel for transmitting low-frequency signals (including the channel where the first operational amplifier UA1 is turned on) keeps operating. Moreover, since the connection between the buffer amplifier UB1 and the first power supply VC1 is disconnected, the buffer amplifier UB1 loses power and its output remains in a high impedance state, i.e., the output of the buffer amplifier UB1 has no effect on the power transistor Q1. It can be seen that the power transistor Q1 is driven by only the low-frequency signal output by the first operational amplifier UA1, that is, the base of the power transistor Q1 is input with only the low-frequency signal, so the second voltage V2 finally obtained is also only the low-frequency signal. At this time, only the channel transmitting the low-frequency signal is running in the signal transmission system 1000.

[0085] Thus, the gain of the signal transmission system 1000 is the gain of the channel for transmitting low-frequency signals, which is V2 / VRE. This gain is related to the gain of the amplifier UC1, and then the controller 120 can calibrate the gain of the amplifier UC1 so that V2 / VRE is equal to the preset gain, thereby achieving the purpose of calibrating the gain of the signal transmission system 1000.

[0086] Secondly, the zero point of the second voltage V2 is related to the offset voltage of the amplifier UC1, and the controller 120 can calibrate the offset voltage of the amplifier UC1 so that when the calibration voltage VRE is 0, the output end of the amplifier UC1 is zero (that is, the second voltage V2 is 0), thereby achieving the purpose of calibrating the zero point of the second voltage V2. In this case, when the signal transmission system 100 is used to transmit the input signal VIN (including high-frequency signals and low-frequency signals), if the voltage of the input signal VIN is zero, the second voltage V2 is also 0.

[0087] In addition, since the switches (including the first single-pole double-throw switch K1, the second single-pole double-throw switch K2 and the controllable switch K3) in the embodiment of the present application are not arranged between the input signal VI N and the first node P1, it is possible to select usable switching devices in actual applications, and it can be applied to high-bandwidth application scenarios, and it is more practical.

[0088] Afterwards, after the gain of the signal transmission system 1000 and the zero point calibration of the second voltage V2 are completed, the controller 120 controls the common end of the first single-pole double-throw switch K1 to be connected to the first connection end (i.e., the input signal VI N is connected to the in-phase input end of the first operational amplifier UA1), and controls the common end of the second single-pole double-throw switch K2 to be connected to the first connection end of the second single-pole double-throw switch K2 (i.e., the output end of the first operational amplifier UA1 is connected to the third resistor R3), and controls the controllable switch K3 to be closed (i.e., the first power supply VC1 is connected to the buffer amplifier UB1), and then, the signal transmission system 100 can be used to transmit the input signal VI N, and has a high transmission accuracy. In this case, the specific working process of the signal transmission system 1000 is as follows:

[0089] On the one hand, the input signal VIN passes through the first capacitor C1, and the high-frequency component of the input signal VIN (i.e., the high-frequency signal in the input signal VIN) is coupled to the input end of the buffer amplifier UB1. The buffer amplifier UB1 is composed of an operational amplifier or discrete components, and the amplification factor is 1. Wherein, if VIN (HF) represents the high-frequency AC component of the input signal VIN; V3 represents the voltage output from the output end of the buffer amplifier U2, V3 (HF) represents the high-frequency AC component output from the output end of the buffer amplifier U2; V4 represents the voltage on the emitter of the power transistor Q1, and V4 (HF) represents the high-frequency AC component of the voltage on the emitter of the power transistor Q1, then VIN (HF) = V3 (HF) = V4 (HF). Wherein, V3 (HF) is used to drive the power transistor Q1 to convert into a high-frequency AC component of a current that is linearly related to V3 (HF) (this current is the current that drives the laser diode D1). At the same time, because the voltage between the base and the emitter of the power transistor Q1 is a fixed voltage of about 0.7V, and the negative power supply V- is also a fixed voltage, they are AC short circuits for high-frequency AC signals. Therefore, the high-frequency AC component ID1 (HF) of the current driving the laser diode D1 can be determined as: ID1 (HF) = VIN (HF) / R4. From this formula, it can be seen that the high-frequency AC component of the current driving the laser diode D1 and the high-frequency AC component in the input signal VIN are linearly related. In this way, an open-loop control method for the high-frequency signal in the input signal VIN is realized.

[0090] On the other hand, the input signal VI N and the voltage on the emitter of the power transistor Q1 are input to the first operational amplifier UA1. Due to the performance limitation of the first operational amplifier UA1, it can only process signals with lower frequencies, which generally do not exceed 10MHz. When the frequency is high, as the frequency increases, the output voltage of the first operational amplifier UA1 gradually decreases until it reaches zero. Therefore, the loop where the first operational amplifier UA1 is located is a loop for processing the low-frequency signal in the input signal VI N. Specifically, the first operational amplifier U1 amplifies the error between the input voltage VI N and V4 (essentially the low-frequency signal in the input voltage VI N and the low-frequency signal in V4), forms a low-frequency error signal and inputs it to the buffer amplifier UB1 through the third resistor R3. Then, the output signal of the buffer amplifier UB1 is input to the base of the power transistor Q1 to be converted into a low-frequency AC component of the current of the laser diode D1 (the current is the current driving the laser diode D1) which is linearly related to V3. It can be seen that the first operational amplifier UA1, the third resistor R3, the buffer amplifier UB1 and the power transistor Q1 form a loop for closed-loop control of the low-frequency signal in the input signal VIN. When the loop works normally, VIN=V4. Then the current of the laser diode D1 is ID1=(VI NV-) / R4=VI N / R4+(-V- / R4). In this formula, VIN / R4 means that the operating current ID1 of the laser diode D1 is linearly related to the input voltage VIN; -V- / R4=Is, Is is the DC operating point current of the laser diode D1. By adjusting V-, the DC operating point current Is of the laser diode D1 can be changed.

[0091] In summary, when the input signal VIN is in the low frequency band, the low-frequency error signal after the difference between VIN and V4 is amplified passes through the output of the first operational amplifier UA1, and is sent to the buffer amplifier UB1 and the power transistor Q1 to output V4, and then fed back to the first operational amplifier UA1 to form a closed loop. At the same time, the high-frequency signal coupled by the first capacitor C1 is 0 and does not work. When the input signal VIN is in the intermediate frequency band, as the input frequency increases, the output signal of the first operational amplifier UA1 becomes smaller, and the output of the buffer amplifier UB1 is gradually determined by the sum of the high-frequency signal coupled by the first capacitor C1 and the output signal of the first operational amplifier UA1. When the input signal VIN is in the high frequency band, the output of the first operational amplifier UA1 is 0, and the output of the buffer amplifier UB1 is completely determined by the high-frequency signal coupled by the first capacitor C1. It can be seen that the signal transmission system 1000 can be applied to the scenarios of high-frequency signals and low-frequency signals, that is, it has a large bandwidth.

[0092] In addition, in this embodiment, a first resistor R1, a second resistor R2 and a second capacitor C2 are further provided to form a phase compensation circuit so that the frequency responses of the high frequency band and the low frequency band are well connected, thereby having a flat frequency response in the entire frequency band.

[0093] It should be noted that if Figure 2 The hardware structure of the signal transmission system 1000 shown is only an example, and the signal transmission system 1000 may have more or fewer components than shown in the figure, may combine two or more components, or may have a different component configuration. The various components shown in the figure may be implemented in hardware, software, or a combination of hardware and software including one or more signal processing and / or application-specific integrated circuits.

[0094] For example, Figure 3 As shown, Figure 3 Another circuit structure of the low-frequency signal processing branch 50 and the signal combining branch 60 is shown as an example.

[0095] In this embodiment, the low-frequency signal processing module 50 includes a second operational amplifier UA2, and the signal combining module includes a composite amplifier UB2.

[0096] The first input terminal of the second operational amplifier UA2 is connected to the first terminal of the first switch module 20, the second input terminal of the second operational amplifier UA2 is connected to the third terminal of the signal conversion module 70, and the output terminal of the second operational amplifier UA2 is connected to the first terminal of the second switch module 30. The first input terminal of the composite amplifier UB2 is connected to the second terminal of the coupling module 10, the second input terminal of the composite amplifier UB2 is connected to the second terminal of the second switch module 30, and the output terminal of the composite amplifier UB2 is connected to the third terminal of the second switch module 30.

[0097] In this embodiment, the composite amplifier UB2 can be a composite amplifier with an amplification factor of 1. In some embodiments, the composite amplifier UB2 can be formed by a dedicated chip BUF802 or other amplifiers of TI Corporation of the United States. The composite amplifier UB2 has two independent signal channels, high frequency and low frequency. And the low frequency channel of the composite amplifier UB2 is the main channel, and the gain of the high frequency channel is controlled by the low frequency channel. Among them, the high frequency channel inputs the high frequency signal of the input signal VI N coupled to the composite amplifier UB2 through the first capacitor C1; the low frequency channel inputs the signal output by the second operational amplifier UA2. The second operational amplifier UA2 is an error amplifier. The signals input to the second operational amplifier UA2 are VI N and V4. The output signal of the second operational amplifier UA2 is directly sent to the low frequency channel of the composite amplifier UB2.

[0098] In this embodiment, when the controller 120 controls the common end of the first single-pole double-throw switch K1 to be connected to the second connection end, and controls the common end of the second single-pole double-throw switch K2 to be connected to the second connection end of the second single-pole double-throw switch K2, and controls the controllable switch K3 to be disconnected, the gain of the signal transmission system 1000 and the zero point of the second voltage V2 can be calibrated. The specific calibration process is the same as that for Figure 2 The instructions are the same as shown and will not be repeated here.

[0099] After the gain of the signal transmission system 1000 and the zero point calibration of the second voltage V2 are completed, the controller 120 controls the common end of the first single-pole double-throw switch K1 to be connected to the first connection end, and controls the common end of the second single-pole double-throw switch K2 to be connected to the first connection end of the second single-pole double-throw switch K2, and controls the controllable switch K3 to be closed. Then, the signal transmission system 100 can be used to transmit the input signal VI N with higher transmission accuracy.

[0100] In this case, when the input signal VIN is in the low frequency band, the low frequency error signal after the difference between VIN and VV is amplified passes through the output of the second operational amplifier UA2, and is sent to the composite amplifier UB2 and the power transistor Q1 to output V4, and then fed back to the second operational amplifier UA2 to form a closed loop. At the same time, the high frequency signal coupled by the first capacitor C1 is 0 and does not work. When the input signal VIN is in the medium frequency band, as the input frequency increases, the output signal of the second operational amplifier UA2 becomes smaller, and the output of the composite amplifier UB2 is gradually determined by the sum of the high frequency signal coupled by the first capacitor C1 and the output signal of the second operational amplifier UA2. When the input signal VIN is in the high frequency band, the output of the second operational amplifier UA2 is 0, and the output of the composite amplifier UB2 is completely determined by the high frequency signal coupled by the first capacitor C1. It can be seen that the voltage-current conversion circuit 100 can be applied to the scene of high frequency signals and low frequency signals, that is, it has a large bandwidth. In addition, since the composite amplifier UB2 used can control the gain of the high-frequency channel with the low-frequency channel as the main channel, the frequency responses of the high-frequency band and the low-frequency band can be well connected, thereby having a flat frequency response in the entire frequency band.

[0101] Please refer to Figure 4 , Figure 4 Flow chart of a control method based on a signal transmission system provided in an embodiment of the present application. Figure 1-Figure 3 The structure shown in the figure is implemented, and the specific implementation process has been described in detail in the above embodiment, which will not be repeated here. Figure 4 As shown, the control method includes the following steps:

[0102] Step 401: Control the first switch module to establish a connection between the voltage source and the first end of the low-frequency signal processing module, control the second switch module to establish a connection between the third end of the low-frequency signal processing module and the third end of the signal compound module, and control the third switch module to disconnect the connection between the first power source and the fourth end of the signal compound module.

[0103] Step 402: Based on the calibration voltage output by the voltage source and the second voltage output by the amplifier module, calibrate the amplification factor of the amplifier module to calibrate the gain of the signal transmission system, and calibrate the offset voltage of the amplifier module to calibrate the zero point of the second voltage.

[0104] Specifically, by executing step 401, the channel for transmitting high-frequency signals can be stopped, and the channel for transmitting low-frequency signals can be kept running, while the signal compound module 60 is powered off and cannot run, so that only the low-frequency signal is input to the signal conversion module 70, and the second voltage V2 finally obtained is also only the low-frequency signal. At this time, only the channel for transmitting low-frequency signals is running in the signal transmission system 1000.

[0105] Then, the gain of the signal transmission system 1000 is the gain of the channel for transmitting low-frequency signals, and the gain is related to the amplification factor of the amplification module 100. Then, the amplification factor of the amplification module 100 can be calibrated to achieve the purpose of calibrating the gain of the signal transmission system 1000. The zero point of the second voltage V2 is related to the offset voltage of the amplification module 100. Then, the offset voltage of the amplification module 100 can be calibrated to achieve the purpose of calibrating the zero point of the second voltage V2.

[0106] In one embodiment, if Figure 5 As shown, in step 402, based on the calibration voltage output by the voltage source and the second voltage output by the amplifying module, the specific implementation process of calibrating the amplification factor of the amplifying module to calibrate the gain of the signal transmission system, and calibrating the offset voltage of the amplifying module to calibrate the zero point of the second voltage includes the following method steps:

[0107] Step 501: When the calibration voltage is 0V, calibrate the offset voltage of the amplifier module to make the second voltage 0V.

[0108] Specifically, by calibrating the offset voltage of the amplifier module 100, when the calibration voltage VRE is 0, the output end of the amplifier module 100 is zero (that is, the second voltage V2 is 0), the purpose of calibrating the zero point of the second voltage V2 can be achieved. In this case, when the signal transmission system 100 is used to transmit the input signal VIN (including high-frequency signals and low-frequency signals), if the voltage of the input signal VIN is zero, the second voltage V2 is also 0.

[0109] Step 502: When the calibration voltage is not 0V, calibrate the amplification factor of the amplification module so that the ratio of the second voltage to the calibration voltage is a preset gain.

[0110] Specifically, the gain of the channel transmitting the low-frequency signal is V2 / VRE, and the gain of the signal transmission system 1000 can be calibrated by calibrating the amplification factor of the amplification module 100 so that V2 / VRE is equal to the preset gain, thereby achieving the purpose of calibrating the gain of the signal transmission system 1000. In this case, when the signal transmission system 100 is used to transmit the input signal VIN (including the high-frequency signal and the low-frequency signal), the gain (V2 / VIN) of the signal transmission system 100 is also equal to the preset gain.

[0111] In one embodiment, after executing step 402, the control method further includes the following method steps: controlling the first switch module to establish a connection between the input signal and the first end of the low-frequency signal processing module, and controlling the second switch module to establish a connection between the third end of the low-frequency signal processing module and the second end of the signal compound module, and controlling the third switch module to establish a connection between the first power supply and the fourth end of the signal compound module.

[0112] Specifically, after the gain and zero point calibration of the signal transmission system 1000 are completed, the controller 120 controls the first switch module 20 to establish a connection between the input signal VI N and the first end of the low-frequency signal processing module 50, and controls the second switch module 30 to establish a connection between the second end of the low-frequency signal processing module 50 and the third end of the signal compound module 60, and controls the third switch module 40 to establish a connection between the first power supply VC1 and the fourth end of the signal compound module 60. Subsequently, the signal transmission system 100 can be used to transmit the input signal VI N with high transmission accuracy.

[0113] It should be understood that the specific control of the signal transmission system 1000 and the beneficial effects produced in the method embodiment can refer to the corresponding description in the above-mentioned embodiment of the signal transmission system 1000, and for the sake of brevity, it will not be repeated here.

[0114] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0115] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them. Under the idea of ​​the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. It should be understood by ordinary technicians in this field that they can still modify the technical solutions recorded in the above embodiments, or replace some of the technical features by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A signal transmission system, characterized in that: include: Coupling module, first switch module, second switch module, third switch module, low-frequency signal processing module, signal compound module, signal conversion module, electro-optical conversion module, photoelectric conversion module, amplification module, voltage source and controller; The first end of the coupling module is connected to the input signal and the second end of the first switch module respectively, the second end of the coupling module is connected to the first end of the signal compound module, the second end of the signal compound module is connected to the second end of the second switch module, the third end of the signal compound module is connected to the first end of the signal conversion module and the third end of the second switch module respectively, the fourth end of the signal compound module is connected to the first end of the third switch module, the second end of the third switch module is connected to the first power supply, the first end of the second switch module is connected to the third end of the low-frequency signal processing module, the first end of the low-frequency signal processing module is connected to the first end of the first switch module, the third end of the first switch module is connected to the voltage source, the second end of the signal conversion module is connected to the first end of the electro-optical conversion module, the third end of the signal conversion module is connected to the second end of the low-frequency signal processing module, the photoelectric conversion module is connected to the amplification module, and the first switch module, the second switch module, the third switch module, the voltage source and the amplification module are all connected to the controller; The coupling module is used to couple the high-frequency signal in the input signal to the first end of the signal compound module; The voltage source is used to output a calibration voltage, and the magnitude of the calibration voltage is determined by the controller; The first switch module is used to be controlled by the controller to establish a connection between the input signal and the first end of the low-frequency signal processing module, or to establish a connection between the voltage source and the first end of the low-frequency signal processing module; The low-frequency signal processing module is used to amplify the difference between the low-frequency signal in the input signal or the calibration voltage and the low-frequency signal in the feedback signal output by the signal conversion module, and output a low-frequency error signal; The second switch module is used to be controlled by the controller to establish a connection between the third end of the low-frequency signal processing module and the second end of the signal compound module, or to establish a connection between the third end of the low-frequency signal processing module and the third end of the signal compound module; The third switch module is used to be controlled by the controller to establish or disconnect the connection between the first power source and the fourth end of the signal combination module; The signal compound module is used to output a composite signal obtained by superimposing the high-frequency signal and the low-frequency error signal to the signal conversion module when the first power supply is connected to the signal compound module, and stop outputting the composite signal when the first power supply is disconnected from the signal compound module; The signal conversion module is used to output a driving current for driving the electro-optical conversion module which has a linear relationship with the composite signal, and is used to generate the feedback signal based on the driving current; The electro-optical conversion module is used to output an optical signal corresponding to the driving current, wherein the optical signal is transmitted through an analog optical fiber; The photoelectric conversion module is used to receive the optical signal from the analog optical fiber and output a first voltage corresponding to the optical signal; The amplification module is used to amplify the first voltage and then output a second voltage; The controller is used to calibrate the amplification factor of the amplification module to calibrate the gain of the signal transmission system, and calibrate the offset voltage of the amplification module to calibrate the zero point of the second voltage when the voltage source is connected to the first end of the low-frequency signal processing module, the third end of the low-frequency signal processing module is connected to the third end of the signal compound module, and the first power supply is disconnected from the fourth end of the signal compound module.

2. The signal transmission system according to claim 1, characterized in that: The coupling module includes a first capacitor; The first end of the first capacitor is connected to the input signal, and the second end of the first capacitor is connected to the first end of the signal combining module.

3. The signal transmission system according to claim 1, characterized in that: The first switch module includes a first single-pole double-throw switch, the second switch module includes a second single-pole double-throw switch, and the third switch module includes a controllable switch; The common end of the first single-pole double-throw switch is the first end of the first switch module, the first connection end of the first single-pole double-throw switch is the second end of the first switch module, and the second connection end of the first single-pole double-throw switch is the third end of the first switch module; The common end of the second single-pole double-throw switch is the first end of the second switch module, the first connection end of the second single-pole double-throw switch is the second end of the second switch module, and the second connection end of the second single-pole double-throw switch is the third end of the second switch module; The controllable switch is connected between the first power supply and the fourth terminal of the signal combining module; Wherein, the control end of the first single-pole double-throw switch, the control end of the second single-pole double-throw switch and the control end of the controllable switch are all connected to the controller.

4. The signal transmission system according to claim 1, characterized in that: The low-frequency signal processing module includes a first resistor, a second resistor, a second capacitor and a first operational amplifier, and the signal compounding module includes a third resistor and a buffer amplifier; The first end of the first resistor is respectively connected to the output end of the first operational amplifier and the first end of the second switch module, the second end of the first resistor is respectively connected to the first end of the second capacitor and the first end of the second resistor, the second end of the second resistor is grounded, the second end of the second capacitor is respectively connected to the second input end of the first operational amplifier and the third end of the signal conversion module, and the first input end of the first operational amplifier is connected to the first end of the first switch module; The first end of the third resistor is connected to the second end of the second switch module, the second end of the third resistor is respectively connected to the input end of the buffer amplifier and the second end of the coupling module, and the output end of the buffer amplifier is respectively connected to the first end of the signal conversion module and the third end of the second switch module.

5. The signal transmission system according to claim 1, characterized in that: The low-frequency signal processing module includes a second operational amplifier, and the signal compounding module includes a compound amplifier; The first input terminal of the second operational amplifier is connected to the first terminal of the first switch module, the second input terminal of the second operational amplifier is connected to the third terminal of the signal conversion module, and the output terminal of the second operational amplifier is connected to the first terminal of the second switch module; The first input end of the composite amplifier is connected to the second end of the coupling module, the second input end of the composite amplifier is connected to the second end of the second switch module, and the output end of the composite amplifier is connected to the third end of the second switch module.

6. The signal transmission system according to claim 1, characterized in that: The signal conversion module includes a power transistor and a fourth resistor; The base of the power transistor is connected to the third end of the signal compound module, the collector of the power transistor is connected to the first end of the electro-optical conversion module, and the emitter of the power transistor is respectively connected to the first end of the fourth resistor and the second end of the low-frequency signal processing module.

7. The signal transmission system according to any one of claims 1 to 6, characterized in that: The signal transmission system also includes a first isolation resistor and a second isolation resistor; The first isolation resistor is connected between the input signal and the second end of the first switch module, and the second isolation resistor is connected between the third end of the signal combination module and the third end of the second switch module.

8. A control method based on the signal transmission system according to any one of claims 1 to 7, characterized in that: The method comprises: Controlling the first switch module to establish a connection between the voltage source and the first end of the low-frequency signal processing module, controlling the second switch module to establish a connection between the third end of the low-frequency signal processing module and the third end of the signal compound module, and controlling the third switch module to disconnect the connection between the first power source and the fourth end of the signal compound module; Based on the calibration voltage output by the voltage source and the second voltage output by the amplifying module, the amplification factor of the amplifying module is calibrated to calibrate the gain of the signal transmission system, and the offset voltage of the amplifying module is calibrated to calibrate the zero point of the second voltage.

9. The method according to claim 8, characterized in that The method of calibrating the amplification factor of the amplifying module based on the calibration voltage output by the voltage source and the second voltage output by the amplifying module to calibrate the gain of the signal transmission system, and calibrating the offset voltage of the amplifying module to calibrate the zero point of the second voltage includes: When the calibration voltage is 0V, calibrating the offset voltage of the amplification module so that the second voltage is 0V; When the calibration voltage is not 0V, the amplification factor of the amplification module is calibrated so that the ratio of the second voltage to the calibration voltage is a preset gain.

10. The method according to claim 8 or 9, characterized in that: After calibrating the amplification factor of the amplifying module to calibrate the gain of the signal transmission system based on the calibration voltage output by the voltage source and the second voltage output by the amplifying module, and calibrating the offset voltage of the amplifying module to calibrate the zero point of the second voltage, the method further includes: The first switch module is controlled to establish a connection between the input signal and the first end of the low-frequency signal processing module, the second switch module is controlled to establish a connection between the third end of the low-frequency signal processing module and the second end of the signal compound module, and the third switch module is controlled to establish a connection between the first power supply and the fourth end of the signal compound module.

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