Synchronizing signal extraction circuit, aircraft detection circuit and equipment

Abstract

The utility model provides a synchronous signal extraction circuit, an aircraft detection circuit and equipment, the synchronous signal extraction circuit comprises an envelope detection unit and a voltage comparison unit, and the envelope detection unit is used for extracting an envelope of a demodulation signal to obtain an envelope electric signal. And the voltage comparison unit is used for outputting an analysis signal of the radio signal according to a comparison result of the envelope electric signal and the first reference voltage Va. Wherein when there is a radio signal of the aircraft in the radio signals, the analytic signal includes a synchronization signal of the aircraft. The synchronization signal extraction circuit is fast in detection speed and high in accuracy for communication signals transmitted by an aircraft such as an FPV aircraft.

Description

Technical Field

[0001] This application relates to the technical field of aircraft detection, and particularly to a synchronization signal extraction circuit, an aircraft detection circuit and a device. Background Art

[0002] FPV (First Person View) is a new gameplay based on installing a wireless camera video transmission device on a remote control aircraft model or vehicle model, enabling the operator to observe and control the model on the ground through a screen. For example, FPV aircraft can be used in occasions such as racing and aerial photography. They are fast and flexible in control, allowing the pilot to fly beyond the line of sight from a first-person perspective, providing a thrilling and realistic flying experience.

[0003] To detect aircraft and prevent the video transmission device carried by the aircraft from capturing images of relevant confidential areas (such as prisons, military bases), it is necessary to detect aircraft in relevant areas. The traditional method is to detect the communication signal between the aircraft and the controller. However, the traditional method has a slow detection speed for communication signals and is vulnerable to interference, resulting in inaccurate detection results for faster aircraft, such as FPV aircraft. Therefore, how to improve the detection speed and accuracy of communication signals has become an urgent problem to be solved. Summary of the Utility Model

[0004] The main purpose of this application is to provide a synchronization signal extraction circuit, an aircraft detection circuit and a device, aiming to improve the detection speed and accuracy of communication signals transmitted by aircraft.

[0005] In a first aspect, an embodiment of this application provides a synchronization signal extraction circuit. The synchronization signal extraction circuit is used to connect to a signal demodulation circuit, and the signal demodulation circuit is used to demodulate the radio frequency signal of the radio signal to obtain a demodulated signal; the synchronization signal extraction circuit includes an envelope detection unit and a voltage comparison unit; the envelope detection unit is used to extract the envelope of the demodulated signal to obtain an envelope electrical signal; the first input terminal of the voltage comparison unit is connected to the envelope detection unit, and the second input terminal of the voltage comparison unit is used to receive a first reference voltage; the voltage comparison unit is used to output an analysis signal of the radio signal according to the comparison result between the envelope electrical signal and the first reference voltage; wherein, when there is a radio signal of an aircraft in the radio signal, the analysis signal includes the synchronization signal of the aircraft.

[0006] In an embodiment, the synchronization signal extraction circuit further includes a voltage follower unit; the input terminal of the voltage follower unit is used to connect to the signal demodulation circuit, and the output terminal of the voltage follower unit is connected to the envelope detection unit.

[0007] In one embodiment, the synchronization signal extraction circuit further includes a first DC blocking unit; the first DC blocking unit is connected between the envelope detection unit and the voltage comparison unit.

[0008] In one embodiment, the synchronization signal extraction circuit further includes a second DC blocking unit; the first end of the second DC blocking unit is used to connect to the signal demodulation circuit, and the second end of the second DC blocking unit is connected to the envelope detection unit.

[0009] In one embodiment, the absolute value of the first reference voltage is greater than the absolute value of the trough amplitude of the synchronization signal, and the absolute value of the first reference voltage is less than the absolute value of the peak amplitude of the synchronization signal.

[0010] In one embodiment, the synchronization signal extraction circuit further includes a signal superposition unit; the first input end of the signal superposition unit is connected to the envelope detection unit, the second input end of the signal superposition unit is used to receive a preset DC component, and the output end of the signal superposition unit is connected to the first input end of the voltage comparison unit; the signal superposition unit is used to superpose the envelope electrical signal and the preset DC component and then output to the voltage comparison unit.

[0011] In one embodiment, the signal superposition unit includes at least one resistor.

[0012] In one embodiment, the signal superposition unit includes a resistor unit and an operational amplifier unit; the first input end of the resistor unit is connected to the envelope detection unit, the second input end of the resistor unit is used to receive a preset DC component, the output end of the resistor unit is connected to the first input end of the operational amplifier unit, the second input end of the operational amplifier unit is grounded, and the output end of the operational amplifier unit is connected to the first input end of the voltage comparison unit.

[0013] In a second aspect, an embodiment of the present application further provides an aircraft detection circuit, including:

[0014] A signal demodulation circuit for demodulating a radio frequency signal of a radio signal to obtain a demodulated signal;

[0015] The synchronization signal extraction circuit as described in any one of the embodiments of the present application, connected to the signal demodulation circuit; wherein, when there is an aircraft radio signal in the radio signal, the synchronization signal extraction circuit is used to output the synchronization signal of the aircraft.

[0016] In a third aspect, an embodiment of the present application further provides an aircraft detection device, including the aircraft detection circuit as described in the embodiment of the present application.

[0017] The synchronization signal extraction circuit provided by the embodiment of the present application includes an envelope detection unit and a voltage comparison unit. Among them, the envelope detection unit is used to extract the envelope of the demodulated signal to obtain an envelope electrical signal. The voltage comparison unit is used to output an analysis signal of the radio signal according to the comparison result between the envelope electrical signal and the first reference voltage. When there is a radio signal of an aircraft in the radio signal, the analysis signal includes the synchronization signal of the aircraft. The embodiment of the present application detects the synchronization signal of the aircraft through the synchronization signal extraction circuit. Since the synchronization signal extraction circuit belongs to a hardware circuit, the detection speed of the communication signal transmitted by the aircraft, such as an FPV aircraft, is fast and the accuracy is relatively high. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0019] Figure 1 It is a circuit schematic diagram of an embodiment of the synchronization signal extraction circuit and the signal demodulation circuit provided by the embodiment of the present application.

[0020] Figure 2 It is a waveform schematic diagram of an embodiment of the envelope electrical signal and the synchronization signal provided by the embodiment of the present application.

[0021] Figure 3 It is a circuit schematic diagram of another embodiment of the synchronization signal extraction circuit provided by the embodiment of the present application.

[0022] Figure 4 It is a circuit schematic diagram of another embodiment of the synchronization signal extraction circuit provided by the embodiment of the present application.

[0023] Figure 5 It is a circuit schematic diagram of another embodiment of the synchronization signal extraction circuit provided by the embodiment of the present application.

[0024] Figure 6 It is a circuit schematic diagram of another embodiment of the synchronization signal extraction circuit provided by the embodiment of the present application.

[0025] Figure 7 It is a circuit schematic diagram of another embodiment of the synchronization signal extraction circuit provided by the embodiment of the present application.

[0026] Figure 8 It is a circuit schematic diagram of another embodiment of the synchronization signal extraction circuit provided by the embodiment of the present application.

[0027] Figure 9Waveform schematic diagram of another embodiment of the envelope electrical signal and the synchronization signal provided by the embodiments of the present application.

[0028] Figure 10 Circuit schematic diagram of an embodiment of the aircraft detection circuit provided by the embodiments of the present application.

[0029] Figure 11 Circuit schematic diagram of an embodiment of the signal demodulation circuit provided by the embodiments of the present application.

[0030] Figure 12 Circuit schematic diagram of another embodiment of the aircraft detection circuit provided by the embodiments of the present application.

[0031] Figure 13 Schematic block diagram of an aircraft detection device provided by the embodiments of the present application.

[0032] The realization, functional features and advantages of the purpose of the present application will be further described with reference to the embodiments and the accompanying drawings. Specific Embodiments

[0033] It should be noted that the terms "first" and "second" in the description, claims and drawings of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0034] In addition, it should be noted that the methods disclosed in the embodiments of the present application or the methods shown in the flowcharts include one or more steps for implementing the methods. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0035] The following will describe in detail some embodiments of the present application with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0036] As Figure 1 shown, Figure 1 Circuit schematic diagram of an embodiment of the synchronization signal extraction circuit provided by the embodiments of the present application.

[0037] Among them, the synchronization signal extraction circuit 100 is used to connect to the signal demodulation circuit 10, and the signal demodulation circuit 10 is used to demodulate the radio frequency signal of the radio signal to obtain a demodulated signal.

[0038] It should be noted that the radio signal can be received through an antenna, and the radio frequency signal of the radio signal can be obtained through antenna processing. For example, the radio signal is received through the antenna, and the antenna converts the radio signal into a radio frequency signal. The radio signal can be a radio signal within a set frequency band, and the set frequency band can be set based on the signal frequency band of the radio signal usually output by the aircraft. For example, it can be set that the set frequency band includes the working frequency band of the radio signal of the aircraft. The signal demodulation circuit 10 can demodulate according to the TV system selected by the aircraft, and the demodulation methods can include Phase Alternating Line (PAL) demodulation, National Television System Committee (NTSC) demodulation, etc.

[0039] Specifically, the synchronization signal extraction circuit 100 includes an envelope detection unit 110 and a voltage comparison unit 120. The envelope detection unit 110 is used to extract the envelope of the demodulated signal to obtain an envelope electrical signal. The first input terminal of the voltage comparison unit 120 is connected to the envelope detection unit 110, and the second input terminal of the voltage comparison unit 120 is used to receive a first reference voltage Va. The voltage comparison unit 120 is used to output an analysis signal of the radio signal according to the comparison result between the envelope electrical signal and the first reference voltage Va. Moreover, during the signal comparison process, the output synchronization signal is also shaped, making the output synchronization signal level value more regular and stable.

[0040] Among them, the envelope electrical signal is obtained by extracting the envelope of the demodulated signal output by the signal demodulation circuit 10. The absolute value of the first reference voltage Va can be greater than the absolute value of the trough amplitude of the synchronization signal, and the absolute value of the first reference voltage Va is less than the absolute value of the peak amplitude of the synchronization signal. The synchronization signal can be, for example, the synchronization signal in the radio signal output by an aircraft, such as an FPV aircraft. The synchronization signal can be a pulse signal, for example, the synchronization signal can be at least a field synchronization signal.

[0041] It should be noted that when there is an aircraft's radio signal in the radio signal, the analysis signal includes the aircraft's synchronization signal. When there is no aircraft's radio signal in the radio signal, the synchronization signal extraction circuit 100 cannot analyze and obtain the aircraft's synchronization signal. Therefore, the analysis signal of the radio signal can be a blank electrical signal or other electrical signals.

[0042] Exemplarily, when the envelope electrical signal is greater than the first reference voltage Va, the voltage comparison unit 120 outputs a first level signal, and when the envelope electrical signal is less than the first reference voltage Va, the voltage comparison unit 120 outputs a second level signal. The first level signal and the second level signal constitute an analysis signal. Therefore, when there is a radio signal of an aircraft in the radio signal, the voltage comparison unit 120 can accurately output the analysis signal of the radio signal according to the comparison result between the envelope electrical signal and the first reference voltage Va.

[0043] Exemplarily, as Figure 2 shown, when there is a radio signal of an aircraft in the radio signal, if the demodulation signal output by the signal demodulation circuit 10 is a CVBS signal (Composite Video Broadcast Signal), the envelope electrical signal is the envelope part of the CVBS. The waveform of the envelope electrical signal can be Figure 2 the waveform 11 represented by the dotted line in. The analysis signal is the synchronization signal of the video signal output by the aircraft. The synchronization signal can be a square wave signal, and the specific waveform of the synchronization signal is Figure 2 the waveform 12 represented by the solid line in.

[0044] It can be understood that in the FPV detection scenario, the FPV aircraft usually uses a television system for broadcast video transmission during flight in the air, so as to facilitate the pilot to control on the ground. Therefore, the radio signal transmitted by the FPV aircraft usually includes a video data signal, and the synchronization signal is an important part of the video data signal. Since the working frequency band of the radio signal of the FPV aircraft is usually a frequency band rarely used in daily life, once a synchronization signal is detected in the set frequency band, it can be determined that there is an FPV aircraft in the relevant area.

[0045] In view of this characteristic, the synchronization signal extraction circuit 100 extracts the synchronization signal by analyzing the radio frequency signal of the radio signal, so as to determine whether there is an aircraft around according to whether the synchronization signal is extracted. It can be understood that the radio signal mentioned in the embodiments of the present application includes the radio signal for communication between the aircraft and the flight control terminal.

[0046] In the embodiment of the present application, when there is a radio signal of an aircraft in the radio signal, the synchronization signal extraction circuit 100 can quickly and effectively output the synchronization signal of the aircraft. Since the synchronization signal extraction circuit 100 is a hardware circuit, the detection speed of the radio signal (communication signal) transmitted by the aircraft, such as the FPV aircraft, is fast and the accuracy is high, which can solve the problems of slow detection speed and low accuracy of the communication signal of the aircraft, such as the FPV aircraft, at present.

[0047] In one embodiment, as Figure 3As shown, the synchronization signal extraction circuit 100 further includes a voltage follower unit 130. The input end of the voltage follower unit 130 is connected to the signal demodulation circuit 10, and the output end of the voltage follower unit 130 is connected to the envelope detection unit 110. Among them, the voltage follower unit 130 is used to perform voltage matching and / or voltage isolation on the demodulation signal output by the signal demodulation circuit 10.

[0048] It should be noted that when there is a radio signal of an aircraft in the radio signal, the signal demodulation circuit 10 outputs a demodulation signal to the voltage follower unit 130. By performing voltage isolation on the demodulation signal through the voltage follower unit 130, the influence of the backend signal on the frontend signal can be avoided. By performing voltage matching on the demodulation signal through the voltage follower unit 130, the function of matching the signal impedance can be achieved.

[0049] Exemplarily, as Figure 4 shown, the voltage follower unit 130 includes a resistor R1, a resistor R2, and an amplifier U1. The first end of the resistor R2 serves as the input end of the voltage follower unit 130, and the second end of the resistor R2 is connected to the first input end of the amplifier U1. The resistor R1 is connected between the second input end and the output end of the amplifier U1, and the output end of the amplifier U1 serves as the output end of the voltage follower unit 130.

[0050] Exemplarily, as Figure 4 shown, the envelope detection unit 110 includes a diode D1, a resistor R3, and a capacitor C3. The anode of the diode D1 serves as the input end of the envelope detection unit 110, and the cathode of the diode D1 serves as the output end of the envelope detection unit 110. The first end of the resistor R3 is connected to the cathode of the diode D1, and the second end of the resistor R3 is grounded. The first end of the capacitor C3 is connected to the cathode of the diode D1, and the second end of the capacitor C3 is grounded. The envelope detection unit 110 is used to extract the envelope of the demodulation signal to obtain an envelope electrical signal, and the envelope electrical signal is, for example, Figure 2 the waveform 11 indicated by the dotted line in

[0051] Exemplarily, as Figure 4 shown, the voltage comparison unit 120 includes a comparator U2. The first input end (which can be, for example, the non-inverting end) of the comparator U2 is connected to the output end of the envelope detection unit 110. The second input end (which can be, for example, the inverting end) of the comparator U2 is used to receive a first reference voltage Va, and the output end of the comparator U2 is used to output an analysis signal. The voltage comparison unit 120 can accurately output an analysis signal according to the comparison result between the envelope electrical signal and the first reference voltage Va. For example, when the envelope electrical signal is greater than the first reference voltage Va, a high-level signal is output, and when the envelope electrical signal is less than the first reference voltage Va, a low-level signal is output. The combination of the high-level signal and the low-level signal constitutes the analysis signal.

[0052] In one embodiment, as shown in Figure 4 FIG. 1, the synchronization signal extraction circuit 100 further includes a first DC blocking unit 140. The first DC blocking unit 140 is connected between the envelope detection unit 110 and the voltage comparison unit 120. The first DC blocking unit 140 is configured to filter out the DC component in the envelope electrical signal output by the envelope detection unit 110, so as to improve the accuracy of the analysis signal obtained by the voltage comparison unit 120.

[0053] Exemplarily, as shown in Figure 4 FIG. 2, the first DC blocking unit 140 includes a DC blocking capacitor C1. By the first DC blocking unit 140, the unstable DC component in the envelope electrical signal, such as the pulsating DC component, is filtered out, thereby improving the stability of the analysis signal output by the voltage comparison unit 120.

[0054] In one embodiment, as shown in Figure 4 FIG. 3, the synchronization signal extraction circuit 100 further includes a second DC blocking unit 150. The first end of the second DC blocking unit 150 is connected to the signal demodulation circuit 10, and the second end of the second DC blocking unit 150 is connected to the envelope detection unit 110. The second DC blocking unit 150 is configured to filter out the DC component in the demodulation signal output by the signal demodulation circuit 10.

[0055] Exemplarily, as shown in Figure 4 FIG. 4, the second DC blocking unit 150 includes a DC blocking capacitor C2. Due to the circuit characteristics, the demodulation signal (such as a video signal) output by the signal demodulation circuit 10 may have an unstable DC component. Therefore, the unstable DC component in the demodulation signal can be filtered out by the second DC blocking unit 150. For example, the pulsating DC component can be filtered out, thereby improving the stability of the demodulation signal output to the envelope detection unit 110.

[0056] In one embodiment, as shown in Figure 5 FIG. 5, the synchronization signal extraction circuit 100 further includes a signal superposition unit 170. The first input terminal of the signal superposition unit 170 is connected to the envelope detection unit 110, the second input terminal of the signal superposition unit 170 is used to receive a preset DC component REF1, and the output terminal of the signal superposition unit 170 is connected to the first input terminal of the voltage comparison unit 120. The signal superposition unit 170 is configured to superpose the envelope electrical signal and the preset DC component REF1 and then output the result to the voltage comparison unit 120.

[0057] Among them, the preset DC component REF1 is a stable DC component, that is, the preset DC component REF1 remains unchanged over time. It should be noted that the envelope electrical signal is superimposed with the stable preset DC component REF1 through the signal superimposing unit 170, so as to improve the stability of the envelope electrical signal. When the voltage comparing unit 120 compares the envelope electrical signal with the first reference voltage Va to output a synchronization signal, and the signal comparison process also shapes the output synchronization signal, making the output synchronization signal level value more regular and stable, so that a more stable and accurate synchronization signal can be obtained, thereby improving the detection accuracy for aircraft, such as FPV aircraft.

[0058] It should be noted that, compared with Figure 1 , Figure 3 or Figure 4 the first reference voltage Va of the voltage comparing unit 120 shown, when the synchronization signal extraction circuit 100 further includes a signal superimposing unit 170, as Figures 5 to 8 shown, the voltage value of the first reference voltage Va is different.

[0059] Exemplarily, taking Figure 3 or Figure 4 the first reference voltage Va of the voltage comparing unit 120 shown as Va1, Figures 5 to 8 the first reference voltage Va shown as Va2, the relationship between Va1 and Va2 can be: Va2 = Va1 + Vb, where Vb is the voltage value corresponding to the preset DC component REF1.

[0060] In one embodiment, the signal superimposing unit 170 includes at least one resistor. The signal superimposing function can be realized through at least one resistor, so as to superimpose the envelope electrical signal with the preset DC component REF1.

[0061] Exemplarily, as Figure 6 shown, the signal superimposing unit 170 is connected between the envelope detection unit 110 and the voltage comparing unit 120. The signal superimposing unit 170 includes a first resistor R4, a second resistor R5 and a third resistor R8. The first end of the first resistor R4 is connected to the envelope detection unit 110, the first end of the second resistor R5 is used to receive the preset DC component REF1, and the first end of the third resistor R8 is grounded. The second ends of the first resistor R4, the second resistor R5 and the third resistor R8 are commonly connected to the voltage comparing unit 120.

[0062] In one embodiment, as Figure 7 , Figure 8As shown, the signal superposition unit 170 includes a resistor unit 171 and an operational amplifier unit 172. The first input terminal of the resistor unit 171 is connected to the envelope detection unit 110. The second input terminal of the resistor unit 171 is used to receive a preset DC component REF1. The output terminal of the resistor unit 171 is connected to the first input terminal of the operational amplifier unit 172. The second input terminal of the operational amplifier unit 172 is used to be grounded. The output terminal of the operational amplifier unit 172 is connected to the first input terminal of the voltage comparison unit 120.

[0063] Among them, the resistor unit 171 includes at least one resistor. The resistor unit 171 may include the first resistor R4, the second resistor R5, and the third resistor R8 as shown in Figure 6 or Figure 8 . Of course, it may also include fewer or more resistors. The operational amplifier unit 172 may include an operational amplifier. Of course, it may also include supporting devices such as resistors. When the signal superposition unit 170 includes the resistor unit 171 and the operational amplifier unit 172, the envelope electrical signal after superimposing the DC component REF1 can be made more stable. Thus, when there is a radio signal of an aircraft in the radio signal, a more stable and more accurate synchronization signal can be obtained.

[0064] In an embodiment, as shown in Figure 8 , the synchronization signal extraction circuit 100 includes a voltage follower unit 130, an envelope detection unit 110, a resistor unit 171, an operational amplifier unit 172, and a voltage comparison unit 120, and also includes DC blocking capacitors C1 and C2. The DC blocking capacitor C1 can isolate the unstable DC component in the envelope electrical signal, and then superimpose the stable preset DC component REF1 into the envelope electrical signal through the amplification process of the operational amplifier unit 172.

[0065] Since the demodulation signal (such as a CVBS signal) output by the signal demodulation circuit 10 is prone to unstable DC components, which appear as fluctuating up and down in the waveform, the embodiment of the present application can first filter out the originally unstable DC component through the DC blocking capacitor C1, and then superimpose the stable preset DC component REF1 through the operational amplifier unit 172. In this way, the voltage comparison unit 120 can obtain a more stable and accurate analysis signal (synchronization signal) by comparing the envelope electrical signal superimposed with the stable DC component with the first reference voltage Va.

[0066] Exemplarily, as shown in Figure 9 , when there is a radio signal of an aircraft in the radio signal, the signal demodulation circuit 10 demodulates the radio frequency signal converted from the radio signal to obtain the demodulation signal of the aircraft (assumed to be a CVBS signal). Then, the synchronization signal extraction circuit 100 extracts the analysis signal of the radio signal from the CVBS signal. At this time, this analysis signal is the synchronization signal.

[0067] The synchronization signal extraction circuit 100 provided by the embodiment of the present application includes an envelope detection unit 110 and a voltage comparison unit 120. Among them, the envelope detection unit 110 is used to extract the envelope of the demodulated signal to obtain an envelope electrical signal. The voltage comparison unit 120 is used to output an analysis signal of the radio signal according to the comparison result between the envelope electrical signal and the first reference voltage Va. When there is a radio signal of an aircraft in the radio signal, the analysis signal includes the synchronization signal of the aircraft. Since the synchronization signal extraction circuit 100 belongs to a hardware circuit, for an aircraft, such as the communication signal transmitted by an FPV aircraft, the detection speed is fast and the detection accuracy is relatively high.

[0068] Please refer to Figure 10 , Figure 10 which is a schematic circuit diagram of an implementation manner of the aircraft detection circuit provided by the embodiment of the present application.

[0069] As Figure 10 shown, the aircraft detection circuit 200 includes:

[0070] A signal demodulation circuit 210, which is used to demodulate the radio frequency signal of the radio signal to obtain a demodulated signal.

[0071] The synchronization signal extraction circuit 220 of the above embodiment, and the synchronization signal extraction circuit 220 is connected to the signal demodulation circuit 210. Among them, when there is a radio signal of an aircraft in the radio signal, the synchronization signal extraction circuit 220 is used to output the synchronization signal of the aircraft.

[0072] It should be noted that the radio signal can be a radio signal received from the outside, such as a radio signal received from the air. The synchronization signal can at least include a field synchronization signal. When the aircraft detection circuit 200 outputs the synchronization signal of the aircraft, it is possible to determine whether there is an aircraft based on the synchronization signal, thereby realizing the detection of the aircraft.

[0073] It should be noted that the signal demodulation circuit 210 can be the signal demodulation circuit 10 described in the above embodiment, and the synchronization signal extraction circuit 220 can be the synchronization signal extraction circuit 100 described in the above embodiment.

[0074] In one embodiment, the signal demodulation circuit 210 can demodulate according to the television standard selected by the aircraft. Such television standards include Phase Alternating Line (PAL) standard, National Television System Committee (NTSC) standard, Sequential Couleur avec Mémoire (SECAM) standard, etc. Specifically, the PAL standard can be further divided into PAL-D standard, PAL-N standard, PAL-M standard, etc.

[0075] Therefore, the demodulation processing methods of the signal demodulation circuit 210 can include PAL demodulation, NTSC demodulation, SECAM demodulation, etc. When there is a radio signal of the aircraft in the radio signal, the demodulated signal can include the video signal of the aircraft. For example, the demodulated signal can be a Composite Video Broadcast Signal (CVBS).

[0076] In one embodiment, as Figure 11 shown, the signal demodulation circuit 210 includes an amplification unit 211, a mixing unit 212, a filtering unit 213, and a demodulation unit 214. Among them, the amplification unit 211 is connected to the antenna, and the amplification unit 211 is used to amplify the radio frequency signal. The mixing unit 212 is connected to the amplification unit 211, and the mixing unit 212 is used to mix the amplified radio frequency signal with a preset local oscillator signal. The filtering unit 213 is connected to the mixing unit 212, and the filtering unit 213 is used to filter the mixed radio frequency signal. The demodulation unit 214 is connected to the filtering unit 213, and the demodulation unit 214 is used to demodulate the filtered radio frequency signal to obtain a demodulated signal.

[0077] It should be noted that the functional units in the signal demodulation circuit 210, such as the amplification unit 211, the mixing unit 212, the filtering unit 213, and the demodulation unit 214, can include specific functional devices to achieve their respective corresponding functions. For example, the amplification unit 211 can include an amplifier for signal amplification, the mixing unit 212 can include a mixer for signal mixing, the filtering unit 213 can include a filter for signal filtering, and the demodulation unit 214 can include a demodulator for signal demodulation processing. Through the multiple functional units in the signal demodulation circuit 210, the radio frequency signal can be demodulated completely and accurately, thereby improving the accuracy of subsequent extraction of the synchronization signal.

[0078] Exemplarily, when there is a radio signal of an aircraft in the radio signal, the radio signal is in PAL format. The signal demodulation circuit 210 performs PAL demodulation on the radio frequency signal to obtain a demodulated signal, which is a composite synchronous video broadcast signal CVBS. The waveform of the CVBS signal is as Figure 2 or Figure 9 shown.

[0079] It can be understood that the specific composition of the signal demodulation circuit 210 may not only be Figure 11 shown, but also some functional units can be added or deleted according to the actual situation, and the connection sequence of each functional unit can also be adjusted. The specific composition of each functional unit may not only include specific functional devices, but also other components such as capacitors and resistors can be added. For example, the amplification unit 211 may include an amplifier and multiple resistors. The embodiments of the present application do not make specific limitations on this.

[0080] In one embodiment, the synchronization signal extraction circuit 220 includes an envelope detection unit 110 and a voltage comparison unit 120. The envelope detection unit 110 is used to extract the envelope of the demodulated signal to obtain an envelope electrical signal. The first input terminal of the voltage comparison unit 120 is connected to the envelope detection unit 110, and the second input terminal of the voltage comparison unit 120 is used to receive a first reference voltage. The voltage comparison unit 120 is used to output an analysis signal of the radio signal according to the comparison result between the envelope electrical signal and the first reference voltage.

[0081] In one embodiment, as Figure 12 shown, the aircraft detection circuit 200 further includes an antenna 230, and the antenna 230 is connected to the signal demodulation circuit 210. Among them, the antenna 230 is used to receive the radio signal and convert the radio signal into a radio frequency signal.

[0082] In one embodiment, as Figure 12 shown, the aircraft detection circuit 200 further includes a control circuit 240, and the control circuit 240 is connected to the signal processing circuit 120. The control circuit 240 is used to generate aircraft detection information based on the synchronization signal.

[0083] Among them, the aircraft detection information may include the presence and absence of an aircraft. Based on the synchronization signal of the aircraft, it is possible to determine whether there are aircraft such as drones and racing drones in the set area, so as to generate relevant aircraft detection information. The set area is within the range of the maximum detection area of the aircraft detection circuit 200, or within the maximum area where the antenna 230 can receive the radio signal. The set area can be set by adjusting the detection ability range of the aircraft detection circuit. The embodiments of the present application do not make specific limitations on this.

[0084] Exemplarily, the control circuit 240 may include a processor. The processor may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor may be a microcontroller unit (MCU), or the processor may also be any conventional processor, etc.

[0085] It should be noted that the control circuit 240 generates the aircraft detection information based on the synchronization signal, which may be generated based on the characteristic information of the synchronization signal. The synchronization signal may at least include a field synchronization signal. The characteristic information of the synchronization signal may include the signal frequency, and may also include parameters such as pulse width, waveform, period, etc. Among them, the pulse width of the television standard is 2.5 times the line period. The aircraft detection information may include detected aircraft and undetected aircraft. When the aircraft detection information includes detected aircraft, the aircraft detection information may further include the detection time point of the aircraft, the continuous detection time, the detection quantity, etc., and the embodiments of the present application do not make specific limitations on this.

[0086] Exemplarily, when there is an aircraft radio signal in the radio signal, the signal demodulation circuit 210 demodulates the radio frequency signal converted from the radio signal to obtain the CVBS signal (demodulated signal) of the aircraft. Then, the synchronization signal extraction circuit extracts the synchronization signal (parsed signal) of the radio signal from the CVBS signal and transmits the synchronization signal to the control circuit 240. The control circuit 240 can generate the aircraft detection information according to the calculation result of the signal frequency by calculating the signal frequency of the synchronization signal.

[0087] Specifically, the control circuit 240 can calculate the signal frequency of the parsed signal, and can compare the signal frequency of the parsed signal with at least one preset synchronization signal frequency to determine whether the signal frequency of the parsed signal is the same as the preset synchronization signal frequency. Each preset synchronization signal frequency corresponds to a synchronization signal frequency of the aircraft measured in advance. If the signal frequency of the parsed signal is the same as any one of the preset synchronization signal frequencies, a first aircraft detection message is generated, and the first aircraft detection message is used to indicate that an aircraft has been detected. If the signal frequency of the parsed signal is different from all the preset synchronization signal frequencies, a second aircraft detection message is generated, and the second aircraft detection message is used to indicate that no aircraft has been detected.

[0088] For example, if the synchronization signal frequency of the aircraft measured in advance is 50 Hz, the preset synchronization signal frequency is set to 50 Hz. If the frequency of the synchronization signal measured by the control circuit 240 is 50 Hz, it can be determined that the radio signal includes the video signal transmitted by the aircraft, and the generated aircraft detection message can be "an aircraft has been detected". If the frequency of the synchronization signal measured by the control circuit 240 is not 50 Hz, it can be determined that the radio signal does not include the video signal transmitted by the aircraft, that is, no aircraft has been detected, and the generated aircraft detection message can be "no aircraft has been detected".

[0089] It can be understood that the beneficial effects that can be achieved by the aircraft detection circuit provided in the embodiments of the present application can refer to the beneficial effects of the synchronization signal extraction circuit in the corresponding embodiments provided above, which will not be elaborated here.

[0090] Please refer to Figure 13 , Figure 13 which is a schematic block diagram of an aircraft detection device provided in an embodiment of the present application.

[0091] As Figure 13 shown, the aircraft detection device 300 includes an aircraft detection circuit 310, and the aircraft detection circuit 310 can be the aircraft detection circuit 200 described in the above embodiments.

[0092] Among them, the aircraft detection device 300 is used to receive external radio signals, analyze and process the radio signals to generate aircraft detection messages, so as to detect an aircraft, such as an FPV aircraft.

[0093] It can be understood that the specific implementation manners of the aircraft detection device provided in the embodiments of the present application can refer to the corresponding processes of the aircraft detection circuit in the corresponding embodiments provided above. The beneficial effects that can be achieved by the aircraft detection device can refer to the beneficial effects of the aircraft detection circuit in the corresponding embodiments provided above, which will not be elaborated here.

[0094] The embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the present application is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present application within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A synchronization signal extraction circuit, characterized in that: The synchronization signal extraction circuit is used to connect to the signal demodulation circuit, and the signal demodulation circuit is used to demodulate the radio frequency signal of the radio signal to obtain a demodulated signal; the synchronization signal extraction circuit includes an envelope detection unit and a voltage comparison unit; The envelope detection unit is used to extract the envelope of the demodulated signal to obtain an envelope electrical signal; The first input end of the voltage comparison unit is connected to the envelope detection unit, and the second input end of the voltage comparison unit is used to receive a first reference voltage; the voltage comparison unit is used to output the analysis signal of the radio signal according to the comparison result between the envelope electrical signal and the first reference voltage; Wherein, when a radio signal of an aircraft exists in the radio signal, the analysis signal includes a synchronization signal of the aircraft.

2. The circuit according to claim 1, characterized in that The synchronization signal extraction circuit also includes a voltage follower unit; The input end of the voltage follower unit is used to connect to the signal demodulation circuit, and the output end of the voltage follower unit is connected to the envelope detection unit.

3. The circuit according to claim 1, characterized in that The synchronization signal extraction circuit further includes a first DC isolation unit; the first DC isolation unit is connected between the envelope detection unit and the voltage comparison unit.

4. The circuit according to claim 1, characterized in that The synchronization signal extraction circuit also includes a second DC isolation unit; a first end of the second DC isolation unit is used to connect to the signal demodulation circuit, and a second end of the second DC isolation unit is connected to the envelope detection unit.

5. The circuit according to claim 1, characterized in that The absolute value of the first reference voltage is greater than the absolute value of the trough amplitude of the synchronization signal, and the absolute value of the first reference voltage is less than the absolute value of the peak amplitude of the synchronization signal.

6. The circuit according to any one of claims 1 to 5, characterized in that: The synchronization signal extraction circuit also includes a signal superposition unit; The first input end of the signal superposition unit is connected to the envelope detection unit, the second input end of the signal superposition unit is used to receive a preset DC component, and the output end of the signal superposition unit is connected to the first input end of the voltage comparison unit; The signal superposition unit is used to superimpose the envelope electrical signal and the preset DC component and output the superimposed signal to the voltage comparison unit.

7. The circuit according to claim 6, characterized in that The signal superposition unit includes at least one resistor.

8. The circuit according to claim 6, characterized in that The signal superposition unit includes a resistance unit and an operational amplifier unit; The first input end of the resistance unit is connected to the envelope detection unit, the second input end of the resistance unit is used to receive a preset DC component, the output end of the resistance unit is connected to the first input end of the operational amplifier unit, the second input end of the operational amplifier unit is used to be grounded, and the output end of the operational amplifier unit is connected to the first input end of the voltage comparison unit.

9. An aircraft detection circuit, characterized in that: include: A signal demodulation circuit is used to demodulate the radio frequency signal of the radio signal to obtain a demodulated signal; The synchronization signal extraction circuit according to any one of claims 1 to 8 is connected to the signal demodulation circuit; wherein, when a radio signal of an aircraft exists in the radio signal, the synchronization signal extraction circuit is used to output the synchronization signal of the aircraft.

10. An aircraft detection device, characterized in that: Comprising the aircraft detection circuit as claimed in claim 9.

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