Signal detection circuit

Abstract

The utility model discloses a signal detection circuit, which comprises a power supply end VCC, a grounding end GND, a signal output end Sout, a photoelectric conversion module, a differential amplification module, a signal filtering module and a comparison output module, the photoelectric conversion module comprises a photoelectric transistor Q1, a resistor R1 and a capacitor C6, the collector electrode of the photoelectric transistor Q1 is connected to the grounding end GND through the resistor R1, and the differential amplification module is connected to the signal output end Sout through the capacitor C6. An emitting electrode of the photoelectric transistor Q1 is connected with a power supply end VCC, and a base electrode of the photoelectric transistor Q1 receives external optical signal input and is used for converting a visible light signal into a voltage signal changing along with illumination intensity; according to the signal detection circuit, a visible light detector, such as a photosensitive diode and a photosensitive resistor, is used for converting an optical signal into a current signal, the magnitude of the current signal can be changed by changing the illumination intensity, the signal can be transmitted by switching the illumination intensity, and the visible light signal is converted into a digital signal.

Description

Technical Field

[0001] This utility model relates to the field of signal technology, specifically to a signal detection circuit. Background Technology

[0002] A signal detection circuit is an electronic circuit used to detect and identify specific signals. Such circuits play a crucial role in various applications, including communication, security detection, and electronic equipment detection. The main function of a signal detection circuit is to capture and identify specific signals. Its working principle typically involves the following steps: signal acquisition: receiving external signals through devices such as antennas or sensors; signal processing: amplifying and filtering the received signals to more clearly identify the target signal; signal identification: determining whether the processed signal is the target signal by comparing and analyzing its characteristics; and output response: based on the identification result, the circuit outputs a corresponding signal or takes a corresponding action.

[0003] Signal detection circuits include antennas, operational amplifiers, filters, comparators, and indicators. They have a wide range of applications. For example, in wireless communication, they are used to receive and identify signals from base stations or mobile devices. In places where the use of mobile phones needs to be prohibited, such as examination rooms and military bases, they can be used to detect mobile phone signals to prevent cheating or illegal communication, or to detect hidden wireless electronic devices, such as wireless microphones and spy cameras.

[0004] In existing technologies, visible light detectors struggle to convert light signals into current signals, making it difficult to alter the current signal magnitude by changing the light intensity, and hindering the transmission of signals by switching light intensities. Since current is an analog signal, it needs to be converted to a digital signal for convenient detection and processing by a microcontroller. Utility Model Content

[0005] The purpose of this section is to outline some aspects of the embodiments of this utility model and to briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be used to limit the scope of this utility model.

[0006] 1. Technical problems to be solved:

[0007] To address the aforementioned issues where visible light detectors struggle to convert light signals into current signals, making it difficult to alter the current signal magnitude by changing light intensity, and hindering the transmission of current signals through switching light intensities, this invention addresses the problem that current, being an analog signal, needs to be converted to a digital signal for convenient microcontroller detection and processing.

[0008] Therefore, the purpose of this invention is to provide a signal detection circuit that utilizes a visible light detector, such as a photodiode or photoresistor, to convert light signals into current signals. Changing the light intensity alters the magnitude of the current signal, and switching the light intensity can transmit the signal. Since current is an analog signal, it needs to be converted into a digital signal for convenient detection and processing by a microcontroller. This invention can convert visible light signals into digital signals.

[0009] 2. Technical Solution:

[0010] To solve the above-mentioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0011] A signal detection circuit includes a power supply terminal VCC, a ground terminal GND, and a signal output terminal S_out, comprising:

[0012] The photoelectric conversion module includes a phototransistor Q1, a resistor R1, and a capacitor C6. The collector of the phototransistor Q1 is connected to the ground terminal GND through the resistor R1, the emitter of the phototransistor Q1 is connected to the power supply terminal VCC, and the base of the phototransistor Q1 receives an external light signal input to convert the visible light signal into a voltage signal that varies with the light intensity.

[0013] The differential amplifier module includes an operational amplifier U1 and resistors R2, R3, R4, and R5. Resistor R2 is connected between the collector of the phototransistor Q1 and the inverting input of the operational amplifier U1; resistor R3 is connected between the non-inverting input of the operational amplifier U1 and the power supply terminal VCC; resistor R4 is connected between the non-inverting input of the operational amplifier U1 and the ground terminal GND; and resistor R5 is connected between the output of the operational amplifier U1 and the inverting input of the operational amplifier U1. This module is used to differentially amplify the voltage signal and output the amplified signal.

[0014] The signal filtering module includes resistors R6 and R7, capacitors C1 and C2, and operational amplifier U2. The input terminal of the operational amplifier is connected to the output terminal of the differential amplifier module, and is used to filter the amplified signal and output a constant DC voltage signal.

[0015] The comparison output module includes comparator U3, resistors R8, R9, and R10, capacitors C3, C4, and C5, and a resettable fuse F1. The signal from the output of the differential amplifier module is filtered by resistor R8 and capacitor C3 and then connected to the non-inverting input of comparator U3. The constant DC voltage signal output by the signal filtering module is filtered by resistor R9 and capacitor C4 and then connected to the inverting input of comparator U3. The output of comparator U3 is connected to resistor R10 and resettable fuse F1, and after decoupling by capacitor C5, it outputs a square wave signal to the signal output terminal S_out. The high level of the square wave signal is approximately equal to the positive voltage of the power supply, and the low level is approximately equal to the negative voltage of the power supply.

[0016] In a preferred embodiment of the signal detection circuit of this utility model, the resistance values ​​of resistors R2, R3, R4, and R5 in the differential amplifier module are coordinated with the gain design of the operational amplifier U1 to suppress background light interference and improve amplification accuracy.

[0017] In a preferred embodiment of the signal detection circuit of this utility model, the resistors R6 and R7, along with the capacitors C1 and C2 in the signal filtering module, form a low-pass filter structure to suppress the high-frequency components of the output signal of the differential amplifier module, thereby enabling the output terminal of the differential amplifier module to obtain a DC voltage close to the average value of the output signal.

[0018] In a preferred embodiment of the signal detection circuit of this utility model, the comparator U3 of the comparison output module forms a threshold comparison between the non-inverting input terminal and the inverting input terminal: the non-inverting input terminal acquires the dynamic signal output by the differential amplifier module; the inverting input terminal acquires the reference DC signal output by the signal filtering module; and by comparing the dynamic signal with the reference DC signal, a digital signal in the form of a square wave is generated for output.

[0019] In a preferred embodiment of the signal detection circuit of this utility model, the resettable fuse F1 is a positive temperature coefficient thermistor, which is used to automatically protect the comparator U3 and the subsequent circuit when an overcurrent or short circuit occurs at the signal output terminal S_out, and restore the normal conduction state after the fault is cleared.

[0020] 3. Beneficial effects:

[0021] Compared with the prior art, the beneficial effects of this utility model are:

[0022] This type of signal detection circuit utilizes visible light detectors, such as photodiodes and photoresistors, to convert light signals into current signals. Changing the light intensity alters the magnitude of the current signal, and switching the light intensity can transmit the signal. Since current is an analog signal, it needs to be converted into a digital signal for easy detection and processing by the microcontroller. This circuit can convert visible light signals into digital signals. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the present utility model will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:

[0024] Figure 1 This is a schematic diagram of the signal terminal of a signal detection circuit according to the present invention;

[0025] Figure 2 This is a schematic diagram of the signal waveform of a signal detection circuit according to the present invention;

[0026] Figure 3 This is a schematic diagram of a constant DC voltage signal for a signal detection circuit according to the present invention;

[0027] Figure 4 This is a schematic diagram of a square wave signal of a signal detection circuit according to the present invention;

[0028] Figure 5 This is a schematic diagram illustrating a signal detection circuit according to the present invention.

[0029] Figure 6 This is a schematic diagram illustrating a signal example of another signal detection circuit according to the present invention. Detailed Implementation

[0030] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0031] This utility model is described in detail with reference to the schematic diagrams. When describing the embodiments of this utility model, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this utility model. In actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0032] The orientation or positional relationship indicated in the terminology is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the present invention and simplifying the description. It is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] The term "connection method" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0034] The embodiments of this utility model will now be described in further detail with reference to the accompanying drawings.

[0035] This utility model provides an overall structural schematic diagram of an embodiment of a signal detection circuit, including:

[0036] Please see Figures 1-5 A signal detection circuit according to this embodiment includes a power supply terminal VCC, a ground terminal GND, and a signal output terminal S_out, comprising:

[0037] The photoelectric conversion module includes a phototransistor Q1, a resistor R1, and a capacitor C6. The collector of the phototransistor Q1 is connected to the ground terminal GND through the resistor R1, the emitter of the phototransistor Q1 is connected to the power supply terminal VCC, and the base of the phototransistor Q1 receives an external light signal input to convert the visible light signal into a voltage signal that varies with the light intensity.

[0038] The differential amplifier module includes an operational amplifier U1 and resistors R2, R3, R4, and R5. Resistor R2 is connected between the collector of the phototransistor Q1 and the inverting input of the operational amplifier U1; resistor R3 is connected between the non-inverting input of the operational amplifier U1 and the power supply terminal VCC; resistor R4 is connected between the non-inverting input of the operational amplifier U1 and the ground terminal GND; and resistor R5 is connected between the output of the operational amplifier U1 and the inverting input of the operational amplifier U1. This module is used to differentially amplify the voltage signal and output the amplified signal.

[0039] The signal filtering module includes resistors R6 and R7, capacitors C1 and C2, and operational amplifier U2. The input terminal of the operational amplifier is connected to the output terminal of the differential amplifier module, and is used to filter the amplified signal and output a constant DC voltage signal.

[0040] The comparison output module includes comparator U3, resistors R8, R9, and R10, capacitors C3, C4, and C5, and a resettable fuse F1. The signal from the output of the differential amplifier module is filtered by resistor R8 and capacitor C3 and then connected to the non-inverting input of comparator U3. The constant DC voltage signal output by the signal filtering module is filtered by resistor R9 and capacitor C4 and then connected to the inverting input of comparator U3. The output of comparator U3 is connected to resistor R10 and resettable fuse F1, and after decoupling by capacitor C5, it outputs a square wave signal to the signal output terminal S_out. The high level of the square wave signal is approximately equal to the positive voltage of the power supply, and the low level is approximately equal to the negative voltage of the power supply.

[0041] It is worth noting that the resistance values ​​of resistors R2, R3, R4, and R5 in the differential amplifier module, in conjunction with the gain design of the operational amplifier U1, are used to suppress background light interference and improve amplification accuracy.

[0042] Next, resistors R6 and R7, along with capacitors C1 and C2 in the signal filtering module, form a low-pass filter structure to suppress the high-frequency components of the output signal of the differential amplifier module, thereby providing the output terminal of the differential amplifier module with a DC voltage close to the average value of the output signal.

[0043] Meanwhile, the comparator U3 of the comparison output module forms a threshold comparison between the non-inverting input terminal and the inverting input terminal: the non-inverting input terminal acquires the dynamic signal output by the differential amplifier module; the inverting input terminal acquires the reference DC signal output by the signal filtering module; by comparing the dynamic signal with the reference DC signal, a digital signal in the form of a square wave is generated for output.

[0044] Furthermore, the resettable fuse F1 is a positive temperature coefficient thermistor, used to automatically protect the comparator U3 and subsequent circuits when an overcurrent or short circuit occurs at the signal output terminal S_out, and to restore normal conduction after the fault is cleared.

[0045] In addition, the circuits, electronic components and modules involved in this utility model are all existing technologies, which can be fully implemented by those skilled in the art, and need not be elaborated upon. The content protected by this utility model does not involve any improvement to the internal structure and method.

[0046] Combination Figures 1-5 The signal detection circuit of this embodiment is used in the following specific way:

[0047] This circuit uses a DC power supply. The VCC signal terminal is the positive terminal, the GND signal terminal is the negative terminal, and the S_out signal terminal is the digital signal output terminal. Figure 1 As shown;

[0048] Subsequently, a light signal receiving circuit is formed by C6, Q1, and R1, where C6 is a decoupling capacitor, Q1 is a photodiode, and R1 is a current-limiting resistor; a differential amplifier circuit is formed by resistors R2, R3, R4, and R5, and operational amplifier U1. After Q1 receives the light signal, the voltage at point A in the circuit will change according to the light intensity, forming a signal waveform; after passing through the differential amplifier circuit, the amplified signal waveform is output at point B. For example... Figure 2 As shown;

[0049] Secondly, a signal filtering circuit is formed by resistors R6 and R7, capacitors C1 and C2, and operational amplifier U2. After passing through the filtering circuit, the signal at point B outputs a constant DC voltage signal at point C, the voltage value of which is approximately equal to the average value of the signal waveform at point B. Figure 3 As shown;

[0050] Next, the signal at point B, after being filtered by resistor R8 and capacitor C3, is connected to the non-inverting input of comparator U3; the signal at point C, after being filtered by resistor R9 and capacitor C4, is connected to the inverting input of U3; point C is the comparator output signal, and resistor R10 provides a pull-up voltage for the output signal; F1 is a PTC, acting as a resettable fuse to protect the output signal from short circuits; capacitor C5 is a decoupling capacitor. After passing through comparator U3, a square wave signal is generated at point D, with the high-level signal approximately equal to VCC voltage and the low-level signal approximately equal to GND. Figure 4 As shown.

[0051] Finally, signal examples are as follows: Figure 5 and Figure 6 As shown: Figure 5 The signal is at point A. Figure 6 The signal is at point D; the vertical axis V represents voltage, the horizontal axis T represents time, and 0 is the origin.

[0052] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in this invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A signal detection circuit, comprising a power supply terminal VCC, a ground terminal GND and a signal output terminal S_out, characterized in that, Also includes: The photoelectric conversion module includes a phototransistor Q1, a resistor R1, and a capacitor C6. The collector of the phototransistor Q1 is connected to the ground terminal GND through the resistor R1, the emitter of the phototransistor Q1 is connected to the power supply terminal VCC, and the base of the phototransistor Q1 receives an external light signal input to convert the visible light signal into a voltage signal that varies with the light intensity. The differential amplifier module includes an operational amplifier U1 and resistors R2, R3, R4, and R5. Resistor R2 is connected between the collector of the phototransistor Q1 and the inverting input of the operational amplifier U1; resistor R3 is connected between the non-inverting input of the operational amplifier U1 and the power supply terminal VCC; resistor R4 is connected between the non-inverting input of the operational amplifier U1 and the ground terminal GND; and resistor R5 is connected between the output of the operational amplifier U1 and the inverting input of the operational amplifier U1. This module is used to differentially amplify the voltage signal and output the amplified signal. The signal filtering module includes resistors R6 and R7, capacitors C1 and C2, and operational amplifier U2. The input terminal of the operational amplifier is connected to the output terminal of the differential amplifier module, and is used to filter the amplified signal and output a constant DC voltage signal. The comparison output module includes comparator U3, resistors R8, R9, and R10, capacitors C3, C4, and C5, and a resettable fuse F1. The signal from the output of the differential amplifier module is filtered by resistor R8 and capacitor C3 and then connected to the non-inverting input of comparator U3. The constant DC voltage signal output by the signal filtering module is filtered by resistor R9 and capacitor C4 and then connected to the inverting input of comparator U3. The output of comparator U3 is connected to resistor R10 and resettable fuse F1, and after decoupling by capacitor C5, it outputs a square wave signal to the signal output terminal S_out. The high level of the square wave signal is approximately equal to the positive voltage of the power supply, and the low level is approximately equal to the negative voltage of the power supply.

2. The signal detection circuit of claim 1, wherein, The resistance values ​​of resistors R2, R3, R4, and R5 in the differential amplifier module, in conjunction with the gain design of the operational amplifier U1, are used to suppress background light interference and improve amplification accuracy.

3. The signal detection circuit of claim 2, wherein, In the signal filtering module, resistors R6 and R7, along with capacitors C1 and C2, form a low-pass filter structure to suppress high-frequency components of the output signal of the differential amplifier module, thereby enabling the output terminal of the differential amplifier module to obtain a DC voltage close to the average value of the output signal.

4. The signal detection circuit of claim 3, wherein, The comparator U3 of the comparison output module forms a threshold comparison between the non-inverting input terminal and the inverting input terminal: the non-inverting input terminal acquires the dynamic signal output by the differential amplifier module; the inverting input terminal acquires the reference DC signal output by the signal filtering module; by comparing the dynamic signal with the reference DC signal, a digital signal in the form of a square wave is generated for output.

5. The signal detection circuit of claim 1, wherein, The resettable fuse F1 is a positive temperature coefficient thermistor, which is used to automatically protect the comparator U3 and the subsequent circuit when an overcurrent or short circuit occurs at the signal output terminal S_out, and restore the normal conduction state after the fault is cleared.

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