A water surface velocity monitoring device installed on a navigation mark

Abstract

This utility model relates to a water surface velocity monitoring device installed on a navigation beacon, comprising a first laser current meter, a second laser current meter, a voltage subtractor, an absolute value module, a Schmitt trigger, an electronic control switch module, and an audible and visual alarm module. The output terminal of the first laser current meter is connected to the inverting input terminal of the voltage subtractor, the output terminal of the second laser current meter is connected to the non-inverting input terminal of the voltage subtractor, the output terminal of the voltage subtractor is connected to the input terminal of the absolute value module, the output terminal of the absolute value module is connected to the input terminal of the Schmitt trigger, the output terminal of the Schmitt trigger is connected to the controlled terminal of the electronic control switch module, one end of the electronic control switch module is connected to a power supply voltage, the other end of the electronic control switch module is connected to the positive terminal of the audible and visual alarm module, and the negative terminal of the audible and visual alarm module is grounded. This utility model allows personnel to intuitively determine whether the water flow velocity collected by the laser current meter is accurate.

Description

Technical Field

[0001] This utility model relates to the field of flow velocity monitoring technology, and is a water surface flow velocity monitoring device installed on a navigation mark. Background Technology

[0002] There are generally two methods for measuring river flow velocity: one is to use an underwater current meter, installed below a navigation mark, to directly measure the speed of the passing water. The advantage of this method is high measurement accuracy; the disadvantages are that it is easily bumped or snagged by debris, which may cause equipment failure, and underwater installation is relatively complex. The other method is to use a surface laser current meter to measure the water flow velocity.

[0003] However, when using laser current meters to measure water flow velocity, the surface water flow velocity can be affected by passing ships, thus affecting the detection results. Utility Model Content

[0004] To address the technical problem that existing technologies using laser flow meters to measure water flow velocity are easily affected by passing ships, thus impacting the detection results, this invention provides a water surface flow velocity monitoring device installed on a navigation mark.

[0005] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0006] A water surface velocity monitoring device installed on a navigation mark includes a first laser velocimeter, a second laser velocimeter, a voltage subtractor, an absolute value module, a Schmitt trigger, an electronically controlled switch module, and an audible and visual alarm module; wherein the first laser velocimeter and the second laser velocimeter are respectively installed at both ends of the navigation mark, and the electronically controlled switch module is a high-level trigger switch;

[0007] The output terminal of the first laser flowmeter is connected to the inverting input terminal of the voltage subtractor, the output terminal of the second laser flowmeter is connected to the non-inverting input terminal of the voltage subtractor, the output terminal of the voltage subtractor is connected to the input terminal of the absolute value module, the output terminal of the absolute value module is connected to the input terminal of the Schmitt trigger, the output terminal of the Schmitt trigger is connected to the controlled terminal of the electronic switch module, the positive terminal of the audible and visual alarm module is connected to the power supply voltage, the negative terminal of the audible and visual alarm module is connected to one end of the electronic switch module, and the other end of the electronic switch module is grounded.

[0008] The beneficial effects of this utility model are as follows: By setting laser flow meters at both ends of the navigation beacon, the voltage signals output by the two laser flow meters are collected. The two output voltage signals are then subtracted by a voltage subtractor to obtain the voltage difference. The absolute value module is then used to take the absolute value of the voltage to ensure that the voltage difference between the two outputs is positive. The voltage difference is then used to determine a threshold value through a Schmitt trigger. When the voltage difference is higher than the threshold set by the Schmitt trigger, the Schmitt trigger outputs a high-level signal. The electronic control switch module is turned on under the trigger control of the high-level signal, and the audible and visual alarm module sounds an alarm. After seeing the alarm signal, the staff can determine that the water flow velocity collected by the laser flow meters is inaccurate during the alarm period, thereby improving the accuracy of monitoring water flow velocity using laser flow meters.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, it also includes a signal amplification module, the non-inverting input of which is connected to the output of the Schmitt trigger, and the output of which is connected to the controlled terminal of the electronically controlled switch module.

[0011] The beneficial effect of adopting the above-mentioned further solution is that by setting a signal amplification module, the output voltage of the Schmitt trigger can be amplified, thereby increasing the driving force of the output voltage of the Schmitt trigger on the electronically controlled switch module.

[0012] Furthermore, the voltage subtractor includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a first operational amplifier;

[0013] One end of the first resistor is connected to the output terminal of the first laser flow meter, and the other end of the first resistor is connected to the inverting input terminal of the first operational amplifier. One end of the second resistor is connected to the output terminal of the second laser flow meter, and the other end of the second resistor is connected to the non-inverting input terminal of the first operational amplifier.

[0014] One end of the third resistor is connected to the inverting input of the first operational amplifier, and the other end of the third resistor is connected to the output of the first operational amplifier. One end of the fourth resistor is connected to the non-inverting input of the first operational amplifier, and the other end of the fourth resistor is grounded. The output of the first operational amplifier is connected to the input of the absolute value module.

[0015] The advantage of adopting the above-mentioned further scheme is that using a basic operational amplifier to construct a subtractor circuit can simplify the circuit structure.

[0016] Furthermore, the absolute value module includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a second operational amplifier, and a third operational amplifier;

[0017] The output terminal of the voltage subtractor is connected to one end of the fifth resistor, one end of the sixth resistor, and one end of the ninth resistor, respectively. The non-inverting input terminal of the second operational amplifier is connected to the other end of the fifth resistor and the other end of the sixth resistor, respectively. The inverting input terminal of the second operational amplifier is connected to one end of the seventh resistor and one end of the eighth resistor, respectively. The output terminal of the second operational amplifier is connected to the other end of the seventh resistor and the other end of the eighth resistor, respectively.

[0018] The output terminal of the second operational amplifier is connected to one end of the tenth resistor and one end of the eleventh resistor, respectively. The non-inverting input terminal of the third operational amplifier is connected to the other end of the tenth resistor and the other end of the eleventh resistor, respectively. The inverting input terminal of the third operational amplifier is connected to the other end of the ninth resistor and one end of the twelfth resistor, respectively. The output terminal of the third operational amplifier is connected to the other end of the twelfth resistor, and the input terminal of the Schmitt trigger is connected to the output terminal of the third operational amplifier.

[0019] The beneficial effect of adopting the above further scheme is that when the input signal is positive, the second operational amplifier acts as a voltage follower. The two inputs of the third operational amplifier are at the same potential as the input signal, so the third operational amplifier simply passes the positive signal to the output. When the input signal is negative, the output of the second operational amplifier is 0 V, and the third operational amplifier inverts the input signal. The overall result is the absolute value of the input signal. Signals up to 10 V can be rectified at frequencies up to 10 kHz. If the signal to be rectified is very small, pull-down resistors at the output of each operational amplifier can improve circuit performance to around 0 V.

[0020] Furthermore, the signal amplification module includes a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, and a fourth operational amplifier;

[0021] One end of the thirteenth resistor is grounded. The inverting input of the fourth operational amplifier is connected to the other end of the thirteenth resistor and one end of the fourteenth resistor. The other end of the fourteenth resistor is connected to the output of the fourth operational amplifier. One end of the fifteenth resistor is connected to the output of the Schmitt trigger. The other end of the fifteenth resistor is connected to the non-inverting input of the fourth operational amplifier. The output of the fourth operational amplifier is connected to the controlled terminal of the electronically controlled switch module.

[0022] Furthermore, the electronically controlled switch module includes a sixteenth resistor and a MOSFET. One end of the sixteenth resistor is connected to the gate of the MOSFET, and the other end of the sixteenth resistor is connected to the source of the MOSFET. The drain of the MOSFET is connected to the negative terminal of the audible and visual alarm module, the source of the MOSFET is grounded, and the gate of the MOSFET is connected to the output terminal of the signal amplification module. The MOSFET is an N-channel MOSFET.

[0023] Furthermore, the audible and visual alarm module includes a warning light and a warning horn. The positive terminals of the warning light and the warning horn are both connected to the power supply voltage, and the drain of the MOSFET is connected to the negative terminals of the warning light and the warning horn, respectively.

[0024] The beneficial effect of adopting the above-mentioned further solution is that by setting up warning lights and warning horns, warning lights and warning horns can be emitted simultaneously, thereby improving the warning effect.

[0025] Furthermore, it also includes a wireless signal transmission module, the signal input terminal of which is connected to the output terminal of the Schmitt trigger, the output terminal of the first laser flow meter, and the output terminal of the second laser flow meter, respectively.

[0026] The beneficial effect of adopting the above-mentioned further solution is that by setting up a wireless signal transmission module, the output voltage signal of the Schmitt trigger can be wirelessly output to the outside, so that relevant personnel can receive the information and improve the transmission distance of the warning information.

[0027] Furthermore, the wireless signal transmission module includes a microcontroller and a wireless communication unit. The signal input terminal of the microcontroller is connected to the output terminal of the Schmitt trigger, the output terminal of the first laser flow meter, and the output terminal of the second laser flow meter, respectively. The signal transceiver terminal of the microcontroller is electrically connected to the signal transceiver terminal of the wireless communication unit.

[0028] The beneficial effect of adopting the above-mentioned further solution is that by using a microcontroller and a wireless communication unit to realize wireless signal transmission, the warning information can be transmitted to the wireless communication terminal via wireless communication, which facilitates real-time understanding of the alarm situation.

[0029] Furthermore, the wireless communication unit is a GPRS communication module, a 4G communication module, or a 5G communication module. Attached Figure Description

[0030] Figure 1 This is a circuit block diagram of the present invention;

[0031] Figure 2 This is the circuit diagram for a voltage subtractor.

[0032] Figure 3 The circuit diagram is for the absolute value module;

[0033] Figure 4 This is the circuit diagram of the signal amplification module;

[0034] Figure 5 This is the circuit diagram of the electronically controlled switch module.

[0035] The attached diagram lists the components represented by each number as follows:

[0036] 1. First laser velocimeter; 2. Second laser velocimeter; 3. Voltage subtractor; 4. Absolute value module; 5. Schmitt trigger; 6. Electrically controlled switch module; 7. Audible and visual alarm module; 8. Signal amplification module; 9. Warning light; 10. Warning horn; 11. Wireless signal transmission module; 12. Microcontroller; 13. Wireless communication unit. Detailed Implementation

[0037] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0038] like Figure 1 As shown, this embodiment provides a water surface velocity monitoring device installed on a navigation mark, including a first laser velocity meter 1, a second laser velocity meter 2, a voltage subtractor 3, an absolute value module 4, a Schmitt trigger 5, a signal amplification module 8, an electronic control switch module 6, and an audible and visual alarm module 7; wherein, the first laser velocity meter 1 and the second laser velocity meter 2 are respectively installed at both ends of the navigation mark, the electronic control switch module 6 is a high-level trigger switch, and the two laser velocity meters respectively detect the water flow velocity at both ends of the navigation mark.

[0039] The output of the first laser velocimeter 1 is connected to the inverting input of the voltage subtractor 3. The output of the second laser velocimeter 2 is connected to the non-inverting input of the voltage subtractor 3. The output of the voltage subtractor 3 is connected to the input of the absolute value module 4. The output of the absolute value module 4 is connected to the input of the Schmitt trigger 5. The output of the Schmitt trigger 5 is connected to the controlled terminal of the electronic switch module 6. The positive terminal of the audible and visual alarm module 7 is connected to the power supply voltage, and the negative terminal of the audible and visual alarm module 7 is connected to one end of the electronic switch module 6. The other end of the electronic switch module 6 is grounded. The non-inverting input of the signal amplification module 8 is connected to the output of the Schmitt trigger 5, and the output of the signal amplification module 8 is connected to the controlled terminal of the electronic switch module 6. By setting the signal amplification module 8, the output voltage of the Schmitt trigger 5 can be amplified to increase the driving force of the output voltage of the Schmitt trigger 5 on the electronic switch module 6.

[0040] like Figure 2As shown, in some embodiments, the voltage subtractor 3 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a first operational amplifier U1.

[0041] One end of the first resistor R1 is connected to the output terminal of the first laser velocimeter 1, and the other end of the first resistor R1 is connected to the inverting input terminal of the first operational amplifier U1. One end of the second resistor R2 is connected to the output terminal of the second laser velocimeter 2, and the other end of the second resistor R2 is connected to the non-inverting input terminal of the first operational amplifier U1.

[0042] One end of the third resistor R3 is connected to the inverting input of the first operational amplifier U1, and the other end of the third resistor R3 is connected to the output of the first operational amplifier U1. One end of the fourth resistor R4 is connected to the non-inverting input of the first operational amplifier U1, and the other end of the fourth resistor R4 is grounded. The output of the first operational amplifier U1 is connected to the input of the absolute value module 4.

[0043] Using a basic operational amplifier to construct a subtractor circuit can simplify the circuit structure; Figure 2 For a subtractor circuit composed of differential amplifiers, the output voltage V0 of the first operational amplifier U1 is -V1. )+V2( ()( V1 represents the output voltage of the first laser velocimeter 1, and V2 represents the output voltage of the second laser velocimeter 2. This indicates the resistance value of the first resistor R1. This indicates the resistance value of the second resistor, R2. This indicates the resistance value of the third resistor, R3. This indicates the resistance value of the fourth resistor, R4; when and At that time, the output voltage V0 = ( (V2-V1), when Then V0 = V2 - V1, therefore, Figure 2 The four resistors R1, R2, R3, and R4 are set to have the same resistance value. The output voltage of the first operational amplifier U1 is V0 = V2 - V1, thus realizing the subtractor function circuit.

[0044] like Figure 3 As shown, the absolute value module 4 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a second operational amplifier U2, and a third operational amplifier U3.

[0045] The output of the first operational amplifier U1 is connected to one end of the fifth resistor R5, one end of the sixth resistor R6, and one end of the ninth resistor R9, respectively. The non-inverting input of the second operational amplifier U2 is connected to the other end of the fifth resistor R5 and the other end of the sixth resistor R6, respectively. The inverting input of the second operational amplifier U2 is connected to one end of the seventh resistor R7 and one end of the eighth resistor R8, respectively. The output of the second operational amplifier U2 is connected to the other end of the seventh resistor R7 and the other end of the eighth resistor R8, respectively.

[0046] The output of the second operational amplifier U2 is connected to one end of the tenth resistor R10 and one end of the eleventh resistor R11, respectively. The non-inverting input of the third operational amplifier U3 is connected to the other end of the tenth resistor R10 and the other end of the eleventh resistor R11, respectively. The inverting input of the third operational amplifier U3 is connected to the other end of the ninth resistor R9 and one end of the twelfth resistor R12, respectively. The output of the third operational amplifier U3 is connected to the other end of the twelfth resistor R12, and the input of the Schmitt trigger 5 is connected to the output of the third operational amplifier U3.

[0047] When the input signal is positive, the second operational amplifier U2 acts as a voltage follower. The two inputs of the third operational amplifier U3 are at the same potential as the input signal, therefore the third operational amplifier U3 simply passes the positive signal to the output. When the input signal is negative, the output of the second operational amplifier U2 is 0V, and the third operational amplifier U3 inverts the input signal. The overall result is the absolute value of the input signal. Signals up to 10V can be rectified at frequencies up to 10kHz. If the signal to be rectified is very small, pull-down resistors at the output of each operational amplifier can improve circuit performance to around 0V.

[0048] like Figure 4 As shown, the signal amplification module 8 includes a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, and a fourth operational amplifier U4.

[0049] One end of the thirteenth resistor R13 is grounded. The inverting input of the fourth operational amplifier U4 is connected to the other end of the thirteenth resistor R13 and one end of the fourteenth resistor R14. The other end of the fourteenth resistor R14 is connected to the output of the fourth operational amplifier U4. One end of the fifteenth resistor R15 is connected to the output of the Schmitt trigger 5, and the other end of the fifteenth resistor R15 is connected to the non-inverting input of the fourth operational amplifier U4. The output of the fourth operational amplifier U4 is connected to the controlled terminal of the electronic switch module 6. The output voltage of its signal amplification module 8 is calculated using the formula Vout = Vin(1 + ... Vin represents the output voltage of Schmitt trigger 5. This indicates the resistance value of the fourteenth resistor, R14. This indicates the resistance value of the thirteenth resistor, R13. It can be seen that by adjusting the resistance values ​​of the fourteenth resistor, R14, and the thirteenth resistor, the amplification factor of the signal amplification module 8 can be changed.

[0050] like Figure 5 As shown, the electronically controlled switch module 6 includes a sixteenth resistor R16 and a MOSFET Q1. One end of the sixteenth resistor R16 is connected to the gate G of the MOSFET Q1, and the other end is connected to the source S of the MOSFET Q1. The drain D of the MOSFET Q1 is connected to the negative terminal of the audible and visual alarm module 7. The source S of the MOSFET Q1 is grounded, and the gate G of the MOSFET Q1 is connected to the output terminal of the signal amplification module 8. The MOSFET Q1 is an N-channel MOSFET. When the Schmitt trigger 5 outputs a high level, the MOSFET Q1 is turned on, the audible and visual alarm module 7 is powered on, and an audible and visual alarm signal is emitted. When the Schmitt trigger 5 outputs a low level, the MOSFET Q1 is turned off, the audible and visual alarm module 7 is powered off, and no audible and visual alarm signal is emitted.

[0051] In some other embodiments, the audible and visual alarm module 7 includes a warning light 9 and a warning horn 10. The positive terminals of both the warning light 9 and the warning horn 10 are connected to the power supply voltage. The drain of the MOSFET Q1 is connected to the negative terminals of both the warning light 9 and the warning horn 10. By configuring the warning light 9 and the warning horn 10, both visual and audible warnings can be emitted simultaneously, thereby improving the warning effect.

[0052] like Figure 1 As shown, in some other embodiments, a wireless signal transmission module 11 is also included. The signal input terminal of the wireless signal transmission module 11 is connected to the output terminal of the Schmitt trigger 5, the output terminal of the first laser velocimeter 1, and the output terminal of the second laser velocimeter 2, respectively.

[0053] By setting up the wireless signal transmission module 11, the output voltage signal of the Schmitt trigger 5 can be wirelessly output to the outside, so that relevant personnel can receive the information and improve the transmission distance of the warning information.

[0054] In some embodiments, the wireless signal transmission module 11 includes a microcontroller 12 and a wireless communication unit 13. The signal input terminal of the microcontroller 12 is connected to the output terminal of the Schmitt trigger 5, the output terminal of the first laser flow meter 1, and the output terminal of the second laser flow meter 2. The signal transceiver terminals of the microcontroller 12 are electrically connected to the signal transceiver terminals of the wireless communication unit 13. The wireless communication unit 13 is a GPRS communication module, a 4G communication module, or a 5G communication module. Since GPRS, 4G, and 5G communication modules are readily available on the market, this invention does not require detailed description of their specific structures. By utilizing the microcontroller and the wireless communication unit to achieve wireless signal transmission, warning information, the output information of the first laser flow meter 1, and the output information of the second laser flow meter 2 can be transmitted wirelessly to a wireless communication terminal, facilitating real-time monitoring of alarm and water flow detection status.

[0055] This embodiment of the invention uses laser flow meters installed at both ends of the navigation beacon to collect the voltage signals output by the two laser flow meters. The two output voltage signals are subtracted using a voltage subtractor 3 to calculate the voltage difference. The absolute value module 4 then takes the absolute value of the voltage difference to ensure it is positive. The voltage difference is then used to determine a threshold value using a Schmitt trigger 5. When the voltage difference exceeds the threshold set by the Schmitt trigger, the trigger outputs a high-level signal, activating the electronic control switch module 6 and triggering an audible and visual alarm. Upon seeing the alarm signal, personnel can determine that the water flow velocity collected by the laser flow meters was inaccurate during the alarm period, thus improving the accuracy of water flow velocity monitoring using laser flow meters. Furthermore, by incorporating hardware with wireless communication capabilities, alarm-related information is transmitted to the mobile terminals of relevant personnel via a wireless communication network.

[0056] It should be noted that using a microcontroller to transmit input electrical signals to mobile terminals such as smartphones via wireless communication networks is a conventional technique in this field. Therefore, this invention does not make any improvements to the microcontroller software, nor does it innovate in computer software and algorithms. Furthermore, all electrical components, integrated circuit modules, or devices in this invention require a power supply. Providing power to integrated circuit modules or devices is common knowledge in this field; therefore, the specific circuitry for powering integrated circuit modules or devices will not be described here. Simply purchase a suitable power supply from the market as needed.

[0057] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A water surface flow rate monitoring device mounted on a navigation mark, characterized by: It includes a first laser velocimeter (1), a second laser velocimeter (2), a voltage subtractor (3), an absolute value module (4), a Schmitt trigger (5), an electronic control switch module (6), and an audible and visual alarm module (7); wherein the first laser velocimeter (1) and the second laser velocimeter (2) are respectively installed at both ends of the navigation beacon, and the electronic control switch module (6) is a high-level trigger switch; The output terminal of the first laser flowmeter (1) is connected to the inverting input terminal of the voltage subtractor (3), the output terminal of the second laser flowmeter (2) is connected to the non-inverting input terminal of the voltage subtractor (3), the output terminal of the voltage subtractor (3) is connected to the input terminal of the absolute value module (4), the output terminal of the absolute value module (4) is connected to the input terminal of the Schmitt trigger (5), the output terminal of the Schmitt trigger (5) is connected to the controlled terminal of the electronic switch module (6), the positive terminal of the audible and visual alarm module (7) is connected to the power supply voltage, the negative terminal of the audible and visual alarm module (7) is connected to one end of the electronic switch module (6), and the other end of the electronic switch module (6) is grounded.

2. A water surface flow velocity monitoring device mounted on a navigation mark according to claim 1, characterized in that: It also includes a signal amplification module (8), the non-inverting input terminal of which is connected to the output terminal of the Schmitt trigger (5), and the output terminal of which is connected to the controlled terminal of the electronic control switch module (6).

3. The water surface velocity monitoring device installed on a navigation mark according to claim 2, characterized in that: The voltage subtractor (3) includes a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), and a first operational amplifier (U1). One end of the first resistor (R1) is connected to the output terminal of the first laser flow meter (1), and the other end of the first resistor (R1) is connected to the inverting input terminal of the first operational amplifier (U1). One end of the second resistor (R2) is connected to the output terminal of the second laser flow meter (2), and the other end of the second resistor (R2) is connected to the non-inverting input terminal of the first operational amplifier (U1). One end of the third resistor (R3) is connected to the inverting input of the first operational amplifier (U1), and the other end of the third resistor (R3) is connected to the output of the first operational amplifier (U1). One end of the fourth resistor (R4) is connected to the non-inverting input of the first operational amplifier (U1), and the other end of the fourth resistor (R4) is grounded. The output of the first operational amplifier (U1) is connected to the input of the absolute value module (4).

4. The water surface velocity monitoring device installed on a navigation mark according to claim 2, characterized in that: The absolute value module (4) includes a fifth resistor (R5), a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8), a ninth resistor (R9), a tenth resistor (R10), an eleventh resistor (R11), a twelfth resistor (R12), a second operational amplifier (U2), and a third operational amplifier (U3). The output terminal of the voltage subtractor (3) is connected to one end of the fifth resistor (R5), one end of the sixth resistor (R6) and one end of the ninth resistor (R9), respectively. The non-inverting input terminal of the second operational amplifier (U2) is connected to the other end of the fifth resistor (R5) and the other end of the sixth resistor (R6), respectively. The inverting input terminal of the second operational amplifier (U2) is connected to one end of the seventh resistor (R7) and one end of the eighth resistor (R8), respectively. The output terminal of the second operational amplifier (U2) is connected to the other end of the seventh resistor (R7) and the other end of the eighth resistor (R8), respectively. The output terminal of the second operational amplifier (U2) is connected to one end of the tenth resistor (R10) and one end of the eleventh resistor (R11), respectively. The non-inverting input terminal of the third operational amplifier (U3) is connected to the other end of the tenth resistor (R10) and the other end of the eleventh resistor (R11), respectively. The inverting input terminal of the third operational amplifier (U3) is connected to the other end of the ninth resistor (R9) and one end of the twelfth resistor (R12), respectively. The output terminal of the third operational amplifier (U3) is connected to the other end of the twelfth resistor (R12), and the input terminal of the Schmitt trigger (5) is connected to the output terminal of the third operational amplifier (U3).

5. The water surface velocity monitoring device installed on a navigation mark according to claim 2, characterized in that: The signal amplification module (8) includes a thirteenth resistor (R13), a fourteenth resistor (R14), a fifteenth resistor (R15), and a fourth operational amplifier (U4). One end of the thirteenth resistor (R13) is grounded. The inverting input of the fourth operational amplifier (U4) is connected to the other end of the thirteenth resistor (R13) and one end of the fourteenth resistor (R14). The other end of the fourteenth resistor (R14) is connected to the output of the fourth operational amplifier (U4). One end of the fifteenth resistor (R15) is connected to the output of the Schmitt trigger (5). The other end of the fifteenth resistor (R15) is connected to the non-inverting input of the fourth operational amplifier (U4). The output of the fourth operational amplifier (U4) is connected to the controlled terminal of the electronic control switch module (6).

6. The water surface velocity monitoring device installed on a navigation mark according to claim 2, characterized in that: The electronic control switch module (6) includes a sixteenth resistor (R16) and a MOS transistor (Q1). One end of the sixteenth resistor (R16) is connected to the gate of the MOS transistor (Q1), and the other end of the sixteenth resistor (R16) is connected to the source of the MOS transistor (Q1). The drain of the MOS transistor (Q1) is connected to the negative terminal of the sound and light alarm module (7). The source of the MOS transistor (Q1) is grounded, and the gate of the MOS transistor (Q1) is connected to the output terminal of the signal amplification module (8). The MOS transistor (Q1) is an N-channel MOS transistor.

7. The water surface velocity monitoring device installed on a navigation mark according to claim 6, characterized in that: The sound and light alarm module (7) includes a warning light (9) and a warning horn (10). The positive terminals of the warning light (9) and the warning horn (10) are connected to the power supply voltage. The drain of the MOS transistor (Q1) is connected to the negative terminals of the warning light (9) and the warning horn (10), respectively.

8. The water surface velocity monitoring device installed on a navigation mark according to claim 1, characterized in that: It also includes a wireless signal transmission module (11), whose signal input terminal is connected to the output terminal of the Schmitt trigger (5), the output terminal of the first laser flow meter (1), and the output terminal of the second laser flow meter (2), respectively.

9. The water surface velocity monitoring device installed on a navigation mark according to claim 8, characterized in that: The wireless signal transmission module (11) includes a microcontroller (12) and a wireless communication unit (13). The signal input terminal of the microcontroller (12) is connected to the output terminal of the Schmitt trigger (5), the output terminal of the first laser flow meter (1), and the output terminal of the second laser flow meter (2), respectively. The signal transceiver terminal of the microcontroller (12) is electrically connected to the signal transceiver terminal of the wireless communication unit (13).

10. The water surface velocity monitoring device installed on a navigation mark according to claim 9, characterized in that: The wireless communication unit (13) is a GPRS communication module, a 4G communication module, or a 5G communication module.

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