A pitch feedback adjusting circuit for a variable pitch propeller based on frequency signal transmission

Abstract

The application discloses a pitch feedback adjusting circuit based on frequency signal transmission of a pitch control propeller, and relates to the technical field of electrical control.The circuit comprises a pitch signal acquisition circuit, a voltage-to-frequency signal transmission circuit and a frequency-to-voltage signal adjusting circuit.The pitch signal acquisition circuit is connected with a pitch potentiometer, used for acquiring and processing a pitch feedback signal and transmitting the signal to the voltage-to-frequency signal transmission circuit to be converted into a frequency signal for long-distance transmission.The frequency-to-voltage signal adjusting circuit converts the long-distance transmitted frequency signal into a voltage signal, and outputs a pitch feedback signal meeting the use requirements of a pitch control propeller ship after signal adjustment.The pitch signal acquisition circuit comprises a signal acquisition circuit, a filter following circuit and a zero point and range adjusting circuit.The voltage-to-frequency signal transmission circuit comprises a voltage / frequency conversion chip and a peripheral circuit thereof.The frequency-to-voltage signal adjusting circuit comprises a frequency / voltage conversion chip and a peripheral circuit thereof.

Description

Technical Field

[0001] This invention relates to the field of electrical control technology, and more specifically, to a pitch feedback adjustment circuit for a pitch control propeller based on frequency signal transmission. Background Technology

[0002] Most controllable pitch propeller pitch feedback signals, both domestically and internationally, are transmitted using analog voltage or current. This means the pitch feedback potentiometer collects mechanical angle information, sends it to the pitch feedback circuit, and after adjustment by the circuitry on the feedback circuit board, transmits the pitch feedback signal as an analog voltage or current. The engine room environment is complex, with numerous electrical devices, generating significant electromagnetic interference. Controllable pitch propeller pitch feedback, transmitted as an analog signal, is most severely affected by electromagnetic interference. Furthermore, the analog pitch feedback signal of controllable pitch propellers is unsuitable for long-distance transmission due to its long transmission distance, often traversing several engine room compartments. This invention leverages the strong anti-interference capability of frequency digital signals by using voltage / frequency conversion and frequency / voltage conversion circuits to transmit the pitch feedback signal as a frequency signal over long distances, thus solving the problem of electromagnetic interference during pitch feedback transmission. Summary of the Invention

[0003] The purpose of this invention is to develop a frequency transmission and adjustment circuit for controllable pitch propeller pitch feedback signals, taking advantage of the strong anti-interference capability of frequency signal transmission, to replace the traditional controllable pitch propeller pitch feedback circuit that transmits analog voltage or current.

[0004] The technical solution of the present invention is: to provide a pitch feedback adjustment circuit for a pitch control propeller based on frequency signal transmission, the circuit comprising: a pitch signal acquisition circuit, a voltage-to-frequency signal transmission circuit, and a frequency-to-voltage signal adjustment circuit;

[0005] The pitch signal acquisition circuit is connected to the pitch potentiometer. The pitch signal acquisition circuit is used to acquire and process the pitch feedback signal sent by the pitch potentiometer. The processed pitch feedback signal is transmitted to the voltage to frequency signal transmission circuit to be converted into a frequency signal for long-distance transmission. After receiving the frequency signal transmitted over long distance, the frequency to voltage signal adjustment circuit converts it back into a voltage signal. After signal adjustment, the pitch feedback signal is output.

[0006] The pitch signal acquisition circuit includes a signal acquisition circuit, a filter and follow circuit, and a range adjustment circuit. The signal acquisition circuit is used to acquire the pitch feedback voltage signal, the filter and follow circuit is used to filter and follow the pitch feedback voltage signal, and the range adjustment circuit is used to adjust the range of the filtered and followed pitch feedback voltage signal.

[0007] The voltage-to-frequency signal transmission circuit includes a voltage / frequency conversion chip and its peripheral circuits. The voltage / frequency conversion chip is used to convert the pitch feedback voltage signal after range adjustment into a frequency signal.

[0008] The frequency-to-voltage signal conditioning circuit includes a frequency / voltage conversion chip and its peripheral circuits. The frequency / voltage conversion chip is used to convert the received frequency signal into a pitch feedback voltage signal and output it.

[0009] In any of the above technical solutions, the pitch signal acquisition circuit is further composed of a signal acquisition circuit, a filter follower circuit, and a range adjustment circuit.

[0010] The signal acquisition circuit consists of a reference power supply and a pitch potentiometer. The reference power supply provides a stable reference voltage signal to the pitch potentiometer to ensure that the pitch potentiometer can accurately output a voltage signal Vin related to the pitch position.

[0011] In any of the above technical solutions, the filter follower circuit further comprises a first operational amplifier and a resistor R4; the negative input terminal of the first operational amplifier receives the filtered Vin signal to form an inverting proportional amplifier follower circuit, which inverts proportionally amplifies the input pitch feedback voltage signal and outputs a unipolar pitch feedback negative voltage signal.

[0012] In any of the above technical solutions, the pitch feedback voltage signal Vin passes through an RC filter circuit consisting of resistors R1 and R2 and capacitor C1 before being input to the first operational amplifier. Resistors R1 and R2 are connected in series between the pitch potentiometer and the negative input terminal of the first operational amplifier, and one end of capacitor C1 is connected between resistors R1 and R2. This RC filter circuit is mainly used to filter out high-frequency noise in the signal to obtain a smoother and more stable pitch voltage signal.

[0013] In any of the above technical solutions, the range adjustment circuit further comprises potentiometers P1 and P2, a second operational amplifier, and diode D3; the unipolar pitch feedback negative voltage signal is connected in parallel with the positive voltage signal output by potentiometer P1 and then connected to the negative input terminal of the second operational amplifier; the second operational amplifier, together with diode D3 and potentiometer P2, constitutes an inverting proportional amplifier adder circuit and a positive voltage follower output circuit; the second operational amplifier finally outputs a positive voltage pitch feedback follower signal Vout1.

[0014] In any of the above technical solutions, furthermore, by adjusting potentiometers P1 and P2, precise control of the pitch feedback signal can be achieved;

[0015] When the pitch control propeller pitch reaches the maximum reverse position, adjusting P1 can minimize the output pitch feedback signal; while during the pitch change from the maximum reverse to the maximum forward, adjusting P2 can adjust the range of the feedback signal throughout the entire stroke.

[0016] In any of the above technical solutions, the frequency-to-voltage signal conditioning circuit further includes an F / V receiving conversion circuit and an output conditioning circuit. The F / V receiving conversion circuit converts the received frequency signal into a pitch feedback voltage signal Vout2 through a frequency / voltage conversion chip. The pitch feedback voltage signal Vout2 is input to the subsequent output conditioning circuit.

[0017] The pitch feedback voltage signal Vout2 is filtered by the RC filter circuit to remove high-frequency noise and then input to the negative input terminal of the third operational amplifier. At the same time, the potentiometer P7 connected to the reference power supply outputs a positive voltage signal VP7 to the positive input terminal of the third operational amplifier, thus forming a pitch feedback signal inverting proportional amplifier subtraction circuit.

[0018] When the controllable pitch propeller is in the mechanical zero thrust pitch position, the output voltage signal VP8 of potentiometer P7 is adjusted so that the output signal Vout3 of the inverting subtractor circuit is zero voltage. At this time, the pitch feedback signal Vout3 output by the third operational amplifier is zero voltage. After passing through the next inverting proportional amplification stage, the pitch feedback signal VOUT output by the fourth operational amplifier is also zero voltage.

[0019] When the controllable pitch propeller is at its maximum forward pitch, the pitch feedback signal Vout3 output by the third operational amplifier is a negative voltage signal. By adjusting potentiometer P8, the proportional amplification factor of the negative voltage signal can be adjusted. Due to the forward conduction of diode D1, after the negative voltage signal passes through the next inverting proportional amplification stage, the fourth operational amplifier outputs a positive voltage pitch feedback signal VOUT. By adjusting potentiometer P8, the positive voltage range of the feedback signal VOUT output at the maximum forward pitch can be adjusted.

[0020] When the controllable pitch propeller is at its maximum reverse pitch, the pitch feedback signal Vout3 output by the third operational amplifier is a positive voltage signal. By adjusting potentiometer P9, the proportional amplification factor of the positive voltage signal can be adjusted. Due to the forward conduction of diode D2, after the positive voltage signal passes through the next inverting proportional amplification stage, the fourth operational amplifier outputs a negative voltage pitch feedback signal VOUT. By adjusting potentiometer P9, the negative voltage range of the feedback signal VOUT output at maximum reverse pitch can be adjusted.

[0021] The beneficial effects of this invention are:

[0022] The technical solution in this invention has the advantages of long frequency transmission signal transmission distance and strong anti-interference capability. It realizes long-distance transmission of pitch feedback signal of pitch control propeller through dedicated V / F and F / V chips.

[0023] This invention enables digital transmission of pitch feedback signals using a voltage / frequency conversion chip and simple peripheral circuitry. It is particularly suitable for complex cabin environments, long transmission distances, and strong electromagnetic interference. It is a simple and practical digital signal transmission and adjustment circuit for pitch feedback of controllable propellers. Attached Figure Description

[0024] The advantages of the above and additional aspects of the present invention will become apparent and readily understood in the description of the embodiments in conjunction with the following drawings, wherein:

[0025] Figure 1 This is a schematic flowchart of a pitch feedback adjustment circuit for a pitch control propeller based on frequency signal transmission according to an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of a pitch signal acquisition circuit for a pitch feedback adjustment circuit based on frequency signal transmission of a pitch control propeller according to an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of a voltage-to-frequency signal transmission circuit for a pitch control propeller pitch feedback adjustment circuit based on frequency signal transmission, according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the F / V receiving and conversion circuit of a pitch control propeller pitch feedback adjustment circuit based on frequency signal transmission according to an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the output adjustment circuit of a pitch control propeller pitch feedback adjustment circuit based on frequency signal transmission according to an embodiment of the present invention. Detailed Implementation

[0030] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0031] In the following description, many specific details are set forth in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0032] like Figure 1As shown, this embodiment provides a pitch feedback adjustment circuit for a pitch control propeller based on frequency signal transmission. The circuit includes: a pitch signal acquisition circuit, a voltage-to-frequency signal transmission circuit, and a frequency-to-voltage signal adjustment circuit.

[0033] The pitch signal acquisition circuit is connected to the pitch potentiometer. The pitch signal acquisition circuit is used to acquire and process the pitch feedback signal sent by the pitch potentiometer. The processed pitch feedback signal is transmitted to the voltage-to-frequency signal transmission circuit to be converted into a frequency signal for long-distance transmission. After receiving the frequency signal transmitted over long distance, the frequency-to-voltage signal adjustment circuit converts it back into a voltage signal. After signal adjustment, it outputs a pitch feedback signal that meets the requirements for use on controllable pitch propeller ships.

[0034] like Figure 2 As shown, the pitch signal acquisition circuit consists of a signal acquisition circuit, a filter follower circuit, and a range adjustment circuit.

[0035] The main function of the signal acquisition circuit is to acquire the pitch feedback voltage signal. In this embodiment, the signal acquisition circuit mainly consists of a reference power supply chip AD581 and a pitch potentiometer. The reference power supply chip AD581 is responsible for providing a stable reference voltage signal to the pitch potentiometer to ensure that the pitch potentiometer can accurately output a voltage signal Vin related to the pitch position. The voltage signal output by the pitch potentiometer directly reflects the real-time position of the pitch, so its accuracy is crucial to the accuracy of the entire system.

[0036] The acquired pitch feedback signal enters a filter follower circuit, which consists of a first operational amplifier and resistor R4, among other components. The negative input of the first operational amplifier receives the filtered Vin signal, forming an inverting proportional amplifier follower circuit. This circuit amplifies the input pitch feedback voltage signal in reverse phase and outputs a unipolar pitch feedback negative voltage signal. Through this design, the filter follower circuit not only maintains signal stability but also enhances the signal's load-carrying capacity, ensuring the accuracy of subsequent processing.

[0037] To further improve the purity of the signal, the pitch feedback voltage signal Vin passes through an RC filter circuit consisting of resistors R1 and R2 and capacitor C1 before being input to the first operational amplifier. Resistors R1 and R2 are connected in series between the pitch potentiometer and the negative input terminal of the first operational amplifier, and one end of capacitor C1 is connected between resistors R1 and R2. This RC filter circuit is mainly used to filter out high-frequency noise in the signal to obtain a smoother and more stable pitch voltage signal.

[0038] Next, the pitch feedback negative voltage signal output by the filter follower circuit enters the range adjustment circuit. The main function of the range adjustment circuit is to adjust the pitch feedback signal from the minimum reverse pitch to the maximum forward pitch, ensuring that the output signal is within the required voltage range. The range adjustment circuit consists of potentiometers P1 and P2, a second operational amplifier, and diode D3. The unipolar pitch feedback negative voltage signal is connected in parallel with the positive voltage signal output by potentiometer P1 and then connected to the negative input terminal of the second operational amplifier. The second operational amplifier, together with diode D3 and potentiometer P2, constitutes an inverting proportional amplifier adder circuit and a positive voltage follower output circuit.

[0039] By adjusting potentiometers P1 and P2, precise control of the pitch feedback signal throughout its entire stroke can be achieved. When the controllable pitch propeller reaches its maximum reverse pitch, adjusting P1 minimizes the output pitch feedback signal; conversely, as the pitch changes from maximum reverse to maximum forward, adjusting P2 adjusts the range of the feedback signal. This design ensures excellent linearity and stability of the pitch feedback signal across the entire pitch variation range.

[0040] Finally, the second operational amplifier outputs a positive voltage pitch feedback follower signal Vout1. This signal is precisely adjusted to provide corresponding feedback voltage values ​​when the pitch control propeller reaches different pitch positions. The introduction of the range adjustment circuit makes the entire signal acquisition process more flexible and accurate, and can adapt to different usage requirements and environmental changes.

[0041] The positive voltage pitch feedback follower signal Vout1 output by the pitch signal acquisition circuit is then converted into a frequency signal by a voltage-to-frequency signal transmission circuit and transmitted to the remote control system, such as... Figure 3 As shown, the voltage-to-frequency signal transmission circuit is mainly implemented using the voltage / frequency conversion chip LM331.

[0042] First, the pitch feedback voltage signal Vout1 is input as a signal through pin 7 to the voltage / frequency conversion chip LM331. This chip has a built-in high-precision voltage-to-frequency conversion function. Through internal voltage comparators, oscillators, and current sources, it converts the input analog voltage signal into a corresponding pulse frequency signal. The frequency signal generated at the output of the LM331 chip is a pulse signal, the frequency of which is proportional to the input voltage signal. This frequency signal can be transmitted to the remote control system via cables, optical fibers, or other transmission media. During transmission, the frequency signal has a higher anti-interference capability than the analog voltage signal, effectively avoiding signal attenuation and noise interference during transmission, thus ensuring signal integrity and reliability. Through this voltage-to-frequency conversion and transmission method, the system can accurately transmit the pitch feedback signal over long distances, ensuring that the remote control system can obtain accurate pitch position information in real time, providing a reliable foundation for subsequent frequency-to-voltage signal adjustment.

[0043] In this embodiment, the LM331 chip is equipped with some necessary peripheral circuits to ensure its normal operation. An RC filter circuit consisting of resistor R10 and capacitor C4 is connected to pin 7 of the chip to remove high-frequency noise from the pitch feedback voltage signal Vout1. A timing resistor Rt and a timing capacitor Ct are connected to pin 5 to configure the internal monostable timing circuit of the LM331-1 chip. By adjusting the voltage values ​​input to pins 6 and 1 of the chip via potentiometer P4, the minimum output frequency of the maximum reverse pitch is adjusted. The pitch feedback voltage signal is converted into a corresponding frequency signal, and the pitch feedback frequency signal Fout is output from pin 1 of the LM331-1 chip to the remote control system.

[0044] After receiving the frequency signal, the remote control system converts the frequency signal back into a pitch feedback voltage signal through a frequency-to-voltage signal conditioning circuit. This circuit includes an F / V receiver conversion circuit and an output conditioning circuit. In this embodiment, the core component of the F / V receiver conversion circuit is also the LM331 chip, used to perform the inverse frequency-to-voltage conversion function.

[0045] like Figure 4 As shown, in the F / V receiver conversion circuit, when the pitch feedback frequency signal Fout is input to the LM331 chip through pin 6, the chip converts the frequency signal into a corresponding analog voltage signal and outputs it from pin 1 through internal frequency counters and voltage integrators. The core of this conversion process is that the chip can generate a corresponding analog voltage signal according to the magnitude of the input frequency; that is, the higher the input frequency, the higher the output voltage, and vice versa.

[0046] Specifically, the frequency signal first enters the frequency counter of the LM331 chip. The counter generates a corresponding digital signal based on the frequency of the input pulse. This digital signal passes through a voltage integrator to generate a continuous analog voltage signal. Pin 1 of the LM331 chip outputs a pitch feedback voltage signal Vout2 that is proportional to the frequency signal Fout.

[0047] The pitch feedback voltage signal Vout2 is input to the subsequent output adjustment circuit. The output adjustment circuit is used to precisely adjust and calibrate the converted pitch feedback voltage signal at the maximum reverse pitch position, the zero thrust pitch position, and the maximum forward pitch position.

[0048] like Figure 5 As shown, the output adjustment circuit consists of components such as operational amplifiers and potentiometers. By amplifying and adjusting the voltage signal, it ensures that the final output pitch feedback voltage signal has high precision and good linearity. At the same time, it ensures that the range adjustment from zero thrust pitch position to maximum forward pitch position and the range adjustment from zero thrust pitch position to maximum reverse pitch position do not interfere with each other and can be adjusted independently.

[0049] The pitch feedback voltage signal Vout2 is filtered by an RC filter circuit to remove high-frequency noise and then input to the negative input terminal of the third operational amplifier. At the same time, the potentiometer P7 connected to the reference power supply outputs a positive voltage signal VP7 to the positive input terminal of the third operational amplifier, thus forming an inverting proportional amplifier and subtraction circuit for the pitch feedback signal.

[0050] When the controllable pitch propeller is in the zero-thrust pitch position, the output voltage signal VP8 of potentiometer P7 is adjusted to make the output signal Vout3 of the inverting subtractor circuit zero. At this time, the pitch feedback signal Vout3 output by the third operational amplifier is zero. After passing through the next inverting proportional amplification stage, the pitch feedback signal VOUT output by the fourth operational amplifier is also zero, that is, the output voltage is 0V at the zero-thrust pitch position.

[0051] When the controllable pitch propeller is at its maximum forward pitch, the pitch feedback signal Vout3 output by the third operational amplifier is a negative voltage signal. The proportional gain of this negative voltage signal can be adjusted by adjusting potentiometer P8. Due to the forward conduction of diode D1, this negative voltage signal passes through the next inverting proportional amplification stage, and the fourth operational amplifier outputs a positive voltage pitch feedback signal VOUT. The range of the positive voltage output of the feedback signal VOUT at maximum forward pitch can be adjusted by adjusting potentiometer P8.

[0052] When the controllable pitch propeller is at its maximum reverse pitch, the pitch feedback signal Vout3 output by the third operational amplifier is a positive voltage signal. The proportional gain of this positive voltage signal can be adjusted by adjusting potentiometer P9. Due to the forward conduction of diode D2, this positive voltage signal passes through the next inverting proportional amplification stage, and the fourth operational amplifier outputs a negative voltage pitch feedback signal VOUT. The range of the negative voltage output of the feedback signal VOUT at maximum reverse pitch can be adjusted by adjusting potentiometer P9.

[0053] In this way, through a series of conversion and adjustment processes, the frequency-to-voltage signal conditioning circuit can accurately restore the remotely transmitted frequency signal to the pitch feedback voltage signal, and generate corresponding feedback signals according to different pitch positions, ensuring that the pitch control propeller can accurately respond to control commands and achieve efficient and precise remote control.

[0054] The units in the device of the present invention can be merged, divided, or reduced according to actual needs.

[0055] Although the invention has been disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and not intended to limit the application of the invention. The scope of protection of the invention is defined by the appended claims and may include various modifications, alterations, and equivalents made to the invention without departing from the scope and spirit of the invention.

Claims

1. A pitch feedback adjustment circuit for a pitch control propeller based on frequency signal transmission, characterized in that, The circuit includes: a pitch signal acquisition circuit, a voltage-to-frequency signal transmission circuit, and a frequency-to-voltage signal adjustment circuit; The pitch signal acquisition circuit is connected to the pitch potentiometer. The pitch signal acquisition circuit is used to acquire and process the pitch feedback signal sent by the pitch potentiometer. The processed pitch feedback signal is transmitted to the voltage to frequency signal transmission circuit to be converted into a frequency signal for long-distance transmission. After receiving the frequency signal transmitted over long distance, the frequency to voltage signal adjustment circuit converts it back into a voltage signal. After signal adjustment, the pitch feedback signal is output. The pitch signal acquisition circuit includes a signal acquisition circuit, a filtering and following circuit, and a range adjustment circuit. The signal acquisition circuit is used to acquire the pitch feedback voltage signal. The filtering and following circuit is used to filter and follow the pitch feedback voltage signal and output it. The range adjustment circuit is used to adjust the range of the filtered and followed pitch feedback voltage signal. The voltage-to-frequency signal transmission circuit includes a voltage / frequency conversion chip and its peripheral circuits. The voltage / frequency conversion chip is used to convert the pitch feedback voltage signal after range adjustment into a frequency signal. The frequency-to-voltage signal conditioning circuit includes a frequency / voltage conversion chip and its peripheral circuits. The frequency / voltage conversion chip is used to convert the received frequency signal into a pitch feedback voltage signal and output it. The frequency-to-voltage signal conditioning circuit includes an F / V receiver conversion circuit and an output conditioning circuit. The F / V receiver conversion circuit converts the received frequency signal into a pitch feedback voltage signal Vout2 through a frequency / voltage conversion chip. The pitch feedback voltage signal Vout2 is input to the subsequent output conditioning circuit. The pitch feedback voltage signal Vout2 is filtered by the RC filter circuit to remove high-frequency noise and then input to the negative input terminal of the third operational amplifier. At the same time, the potentiometer P7 connected to the reference power supply outputs a positive voltage signal VP7 to the positive input terminal of the third operational amplifier, thus forming a pitch feedback signal inverting proportional amplifier subtraction circuit. When the controllable pitch propeller is in the mechanical zero thrust pitch position, the output voltage signal VP8 of potentiometer P7 is adjusted so that the output signal Vout3 of the inverting subtractor circuit is zero voltage. At this time, the pitch feedback signal Vout3 output by the third operational amplifier is zero voltage. After passing through the next inverting proportional amplification stage, the pitch feedback signal VOUT output by the fourth operational amplifier is also zero voltage. When the controllable pitch propeller is at its maximum forward pitch, the pitch feedback signal Vout3 output by the third operational amplifier is a negative voltage signal. By adjusting potentiometer P8, the proportional amplification factor of the negative voltage signal can be adjusted. Due to the forward conduction of diode D1, after the negative voltage signal passes through the next inverting proportional amplification stage, the fourth operational amplifier outputs a positive voltage pitch feedback signal VOUT. By adjusting potentiometer P8, the positive voltage range of the feedback signal VOUT output at the maximum forward pitch can be adjusted. When the controllable pitch propeller is at its maximum reverse pitch, the pitch feedback signal Vout3 output by the third operational amplifier is a positive voltage signal. By adjusting potentiometer P9, the proportional amplification factor of the positive voltage signal can be adjusted. Due to the forward conduction of diode D2, after the positive voltage signal passes through the next inverting proportional amplification stage, the fourth operational amplifier outputs a negative voltage pitch feedback signal VOUT. By adjusting potentiometer P9, the negative voltage range of the feedback signal VOUT output at maximum reverse pitch can be adjusted.

2. The pitch feedback adjustment circuit for a pitch-controlled propeller based on frequency signal transmission as described in claim 1, characterized in that, The pitch signal acquisition circuit specifically consists of a signal acquisition circuit, a filter follower circuit, and a range adjustment circuit. The signal acquisition circuit consists of a reference power supply and a pitch potentiometer. The reference power supply provides a stable reference voltage signal to the pitch potentiometer to ensure that the pitch potentiometer can accurately output a voltage signal Vin related to the pitch position.

3. The pitch feedback adjustment circuit for a pitch-controlled propeller based on frequency signal transmission as described in claim 2, characterized in that, The filter follower circuit consists of a first operational amplifier and a resistor R4. The negative input terminal of the first operational amplifier receives the filtered Vin signal, forming an inverting proportional amplifier follower circuit. This inverting proportional amplifier follower circuit amplifies the input pitch feedback voltage signal in an inverting proportional manner and outputs a unipolar pitch feedback negative voltage signal.

4. The pitch feedback adjustment circuit for a pitch-controlled propeller based on frequency signal transmission as described in claim 3, characterized in that, The pitch feedback voltage signal Vin passes through an RC filter circuit consisting of resistors R1 and R2 and capacitor C1 before being input to the first operational amplifier. Resistors R1 and R2 are connected in series between the pitch potentiometer and the negative input terminal of the first operational amplifier, and one end of capacitor C1 is connected between resistors R1 and R2. This RC filter circuit is mainly used to filter out high-frequency noise in the signal to obtain a smoother and more stable pitch voltage signal.

5. The pitch feedback adjustment circuit for a pitch-controlled propeller based on frequency signal transmission as described in claim 3, characterized in that, The range adjustment circuit consists of potentiometers P1 and P2, a second operational amplifier, and diode D3. The unipolar pitch feedback negative voltage signal is connected in parallel with the positive voltage signal output by potentiometer P1 and then connected to the negative input terminal of the second operational amplifier. The second operational amplifier, together with diode D3 and potentiometer P2, constitutes an inverting proportional amplifier adder circuit and a positive voltage follower output circuit. The second operational amplifier finally outputs a positive voltage pitch feedback follower signal Vout1.

6. The pitch feedback adjustment circuit for a pitch-controlled propeller based on frequency signal transmission as described in claim 5, characterized in that, By adjusting potentiometers P1 and P2, precise control of the pitch feedback signal can be achieved. When the pitch of the controllable propeller reaches the maximum reverse position, adjusting P1 can minimize the output pitch feedback signal; and after the pitch changes from the maximum reverse to the maximum forward position, adjusting P2 can adjust the range of the feedback signal throughout the entire stroke.

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