An ADS-B active antenna

Abstract

The application relates to the field of ADS-B technology, in particular to an ADS-B active antenna which comprises a shell and a glass steel rod-shaped antenna, the bottom end of the shell is connected with a sealing bottom plate through screws, the top end of the shell is provided with an antenna radiation mechanism for signal receiving, the inside of the shell is provided with a signal connection processing mechanism for signal connection and processing, and four groups of mounting holes are arranged in the bottom end of the shell. The application is designed in an integrated mode, so that the installation steps are greatly simplified, the deployment time is saved, the durability and reliability of the application in a rain, snow and high-humidity environment are improved, the structural integrity and connection reliability of the application in a vibration environment are improved, the noise suppression effect is gradually deepened, the signal accuracy is improved, and the adaptability of the application is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the field of ADS-B technology, and particularly relates to an ADS-B active antenna. BACKGROUND

[0002] ADS-B (Automatic Dependent Surveillance-Broadcast) technology is one of core technologies in the fields of aviation and ground traffic monitoring, and an ADS-B antenna, as a key component for signal receiving / transmitting, needs to be adapted to the use scenarios of fixed platforms (such as base stations) and mobile platforms (such as military vehicles and unmanned aerial vehicles); the environmental adaptability of the ADS-B antenna is extremely high for the mobile platforms such as military vehicles: the ADS-B antenna needs to withstand a wide temperature range of-40 DEG C to +85 DEG C, outdoor moisture intrusion, vehicle bumping and vibration, and at the same time, the low-loss property and anti-interference property of signal receiving need to be ensured to avoid performance failure caused by structural design defects.

[0003] The existing ADS-B antennas are mostly designed for fixed scenarios, and in the bumping scenario of the mobile platform, the anti-vibration property of the ADS-B antenna is insufficient, which leads to structural loosening or element damage, and leads to the problems of poor waterproof sealing property, poor maintenance convenience, and poor accuracy of processing of received signals, so that the long-term stable use requirement of the military vehicles and other special scenarios cannot be met. SUMMARY

[0004] The application aims to provide an ADS-B active antenna to solve the problems that the existing ADS-B antennas are mostly designed for fixed scenarios, and in the bumping scenario of the mobile platform, the anti-vibration property of the ADS-B antenna is insufficient, which leads to structural loosening or element damage, and leads to the problems of poor waterproof sealing property, poor maintenance convenience, and poor accuracy of processing of received signals, so that the long-term stable use requirement of the military vehicles and other special scenarios cannot be met.

[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme: an ADS-B active antenna, comprising a shell and a glass steel rod-shaped antenna, a sealing bottom plate is connected to the bottom end of the shell through a screw, an antenna radiation mechanism for signal receiving is arranged at the top end of the shell, a signal connection and processing mechanism for signal connection and processing is arranged in the shell, and four groups of mounting holes are formed in the bottom end of the shell.

[0006] Preferably, the bottom end of the shell is uniformly fixedly connected with a positioning block, edges of the sealing bottom plate are uniformly provided with positioning grooves, the positioning block is located in the positioning groove, and sealing pads are arranged between the shell and the sealing bottom plate and between the waterproof and breathable valve and the shell.

[0007] Preferably, the antenna radiation mechanism comprises a first square support seat, a second square support seat and a glass steel rod-shaped antenna, the top end of the shell is provided with the glass steel rod-shaped antenna, the top end of the shell is provided with the first square support seat, the first square support seat is located on one side of the glass steel rod-shaped antenna, the top end of the shell is provided with the second square support seat corresponding to the first square support seat, and the second square support seat is attached to one side of the first square support seat, the corrosion resistance and service life of the glass steel rod-shaped antenna are improved, the connection mode of the shell, the glass steel rod-shaped antenna, the first square support seat and the second square support seat is a double fixing mode of holding and bottom connection, an anti-vibration structure is formed, the glass steel rod-shaped antenna is effectively prevented from loosening or breaking, the glass steel rod-shaped antenna is located between the first square support seat and the second square support seat, the first square support seat and the second square support seat are connected through screws, sealing pads are arranged between the first square support seat and the second square support seat and between the bottom ends of the first square support seat and the second square support seat and the shell, the glass steel rod-shaped antenna is held by the first square support seat and the second square support seat, and the first square support seat and the second square support seat are connected to the top end of the shell through screws, so that an anti-vibration structure is formed, and the sealing property of the shell is improved.

[0008] Preferably, the signal connection processing mechanism comprises a partition plate, a low-noise amplifier plate, a first N-type connector and a second N-type connector, the inside of the shell is provided with the partition plate, the top end of the partition plate is provided with the low-noise amplifier plate, the top end of the low-noise amplifier plate is attached to the inner wall of the top end of the shell, the partition plate and the low-noise amplifier plate are connected to the shell through screws, one end of the shell is connected with the first N-type connector through screws, the input end of the first N-type connector is electrically connected with the low-noise amplifier plate, the top end of the shell is connected with the second N-type connector electrically connected with the low-noise amplifier plate through screws, for processing of signals, ensuring the clarity and accuracy of signals, the partition plate and the inner wall of the shell form an independent shielding cavity, the low-noise amplifier plate is located in the inside of the partition plate, the top end of the second N-type connector is located in the inside of the glass steel rod-shaped antenna, and sealing pads are arranged between the first N-type connector and the shell, improving the sealing property of the shell.

[0009] Preferably, the low noise amplifier board comprises a control unit including an FPGA core processing module for processing real-time data and generating control instructions, the FPGA core processing module being of XC7K325T chip model to meet the signal processing requirements;

[0010] The pre-processing unit comprises a limiter and a filter, the limiter being a first-stage protection device for limiting the power amplitude of the input signal after the signal enters the low noise amplifier board, and the filter being used for pre-filtering noise signals outside the passband.

[0011] The signal processing unit comprises a first-order adaptive filter circuit, a second-order adaptive filter circuit and a third-order adaptive filter circuit, which are respectively used for preliminary filtering, moderate filtering and final filtering of the noise in the pre-processed signal.

[0012] The noise detection unit is used for collecting the noise amplitude of the signal and judging whether the noise meets the preset noise error threshold, the noise detection unit being of AD8461 peak detection circuit model, the noise peak value in a signal cycle being collected as the noise amplitude judgment basis, and the detection accuracy being 0.001V.

[0013] Preferably, the signal processing unit further comprises a first-order low noise amplification circuit, a second-order low noise amplification circuit and a third-order low noise amplification circuit, which are all used for amplifying the noise in the signal processed by the signal processing unit.

[0014] Preferably, the first-order low noise amplification circuit, the second-order low noise amplification circuit and the third-order low noise amplification circuit are all provided with an adaptive bias circuit, the adaptive bias circuit being used for adjusting the bias voltage in real time according to the input signal strength of the corresponding amplification circuit to ensure the gain stability of each order of amplification circuit and avoid signal distortion, the adaptive bias circuit comprising a voltage detection module and an adjustable voltage stabilizing module, the voltage detection module being of AD8210 model and the adjustable voltage stabilizing module being of LM317 model, the bias voltage being adjusted in real time according to the input signal strength, and the first-order low noise amplification circuit, the second-order low noise amplification circuit and the third-order low noise amplification circuit being constructed by GaAs field effect tubes of ATF-54143 model.

[0015] Preferably, the noise detection unit adopts a peak detection circuit, which takes the noise peak value in a signal cycle as the noise amplitude judgment basis, and the preset noise error threshold is adjusted by the upper computer according to the actual application scene, for example, the adjustment range is 0.005V-0.02V; in the complex electromagnetic interference scene such as airport, the threshold is set to 0.005V to improve the noise reduction precision; in the less interference scene such as open area, the threshold is set to 0.02V to improve the signal processing efficiency.

[0016] Preferably, the first-order adaptive filter circuit dynamically adjusts the filter parameters based on the least mean square error algorithm, the convergence speed is set to 0.01, and the narrow-band interference noise that is not eliminated in the preliminary filtering is mainly suppressed to improve the suppression ability of dynamic interference noise; the second-order adaptive filter circuit adopts an improved least mean square error algorithm, the convergence speed is improved to 0.02, and the steady-state error is reduced, thereby improving the identification and suppression ability of weak noise; the third-order adaptive filter circuit adopts a crystal filter structure, the crystal filter structure is a filter structure composed of a quartz crystal resonator as a core filter element, the passband range is accurately locked to 1089MHz-1091MHz, the final filtering of interference noise is realized, and weak interference noise close to the ADS-B signal frequency can be effectively filtered out.

[0017] Preferably, the operation method of the ADS-B active antenna comprises:

[0018] S1: signal preprocessing, receiving and transmitting signals through the glass steel rod antenna and the second N-type connector, and pre-processing the signals entering the low noise amplifier board through the amplitude limiter and the filter to facilitate subsequent signal processing;

[0019] S2: first cycle processing;

[0020] S2-1: preliminary filtering and noise reduction: the received pre-processed signals are preliminarily filtered by the first-order adaptive filter circuit to filter out high-frequency interference noise outside the 1090MHz core frequency band, the passband range of the first-order adaptive filter circuit is 1085MHz-1095MHz, and the first-order adaptive filter circuit has the characteristics of small insertion loss and flat passband, thereby ensuring the effective reservation of the ADS-B original signal;

[0021] S2-2: signal amplification: the preliminarily filtered signals are input into the first-order low noise amplification circuit, the gain of the first-order low noise amplification circuit is set to 15dB, the noise coefficient is less than 1.5dB, the signal amplitude is amplified to 0.2V-0.3V, and the signal strength meets the subsequent processing requirements;

[0022] S2-3: Secondary filtering and noise reduction: The amplified signal is filtered again by a first-order adaptive filter circuit, and the convergence speed is set to 0.01. The focus is on suppressing narrowband interference noise that has not been eliminated in the preliminary filtering;

[0023] S2-4: Noise detection: The noise amplitude of the signal after the first cycle of processing is collected by the noise detection unit and compared with the preset noise error threshold of 0.01V. If it is less than the preset noise error threshold, it is output through the first N-type connector. If the noise amplitude is greater than the preset noise error threshold, it enters the second cycle of processing;

[0024] S3: Second cycle of processing;

[0025] S3-1: Moderate filtering and noise reduction: The signal after the first cycle of processing is input into a second-order adaptive filter circuit. The passband range of the second-order adaptive filter circuit is narrowed to 1088MHz-1092MHz, and the passband ripple is less than 0.5dB. This further filters out interference noise at the edge of the frequency band and improves the selectivity of the filter;

[0026] S3-2: Precise signal amplification: The filtered signal from S3-1 is input into a second-order low-noise amplification circuit. The gain adjustment range is 10dB-20dB, which amplifies the signal amplitude to 0.5V-0.6V. An adaptive bias circuit is set to avoid signal saturation distortion;

[0027] S3-3: Fine filtering and noise reduction: The amplified signal from S3-2 is filtered again by a second-order adaptive filter circuit. The convergence speed is increased to 0.02, and the steady-state error is reduced. This improves the ability to identify and suppress weak noise;

[0028] S3-4: Secondary noise detection: The noise amplitude of the signal is collected again by the noise detection unit. If it is still less than the preset noise error threshold, it is output through the first N-type connector. If it is still greater than the preset noise error threshold, it enters the third cycle of processing;

[0029] S4: Third cycle of processing;

[0030] S4-1: Filtering and noise reduction: The signal after the second cycle of processing is input into a third-order adaptive filter circuit. The passband range is precisely locked at 1089MHz-1091MHz, which filters out interference noise and effectively filters out weak interference noise close to the frequency of ADS-B signals;

[0031] S4-2: Signal stable amplification: The signal after S4-1 processing is input into a third-order low-noise amplification circuit with a constant gain of 10dB. The signal amplitude is amplified to 0.8V-1.0V to ensure signal amplitude stability;

[0032] S4-3: Final filtering noise reduction: the signal amplified by S4-2 is finally filtered through a third-order adaptive filtering circuit;

[0033] S4-4: Final noise detection: the noise amplitude of the signal after the third cycle processing is collected to realize the final signal processing;

[0034] S5: the signal in S4-4 is output through the first N-type connector.

[0035] Compared with the prior art, the application has the following beneficial effects:

[0036] 1、The application adopts integrated design, and the application is a complete body after leaving the factory, so that only the shell needs to be fixed by a mounting hole and a bolt and a cable needs to be connected during on-site installation, thereby greatly simplifying the installation steps and saving deployment time;

[0037] 2、The glass rod-shaped antenna in the application can effectively avoid the problem of damp corrosion even if the glass rod-shaped antenna is exposed to rain, snow, salt mist and high humidity environment for a long time when applied to a military vehicle or an outdoor environment, water intrusion is effectively prevented through the design of the shell combined with multiple sealing pads, and the durability and reliability of the application in rain, snow and other harsh environments are significantly improved;

[0038] 3、The waterproof breather valve adopts a threaded connection design, and does not need to disassemble the main structure of the application when replacing, thereby greatly reducing the maintenance difficulty and time cost;

[0039] 4、The first N-type connector and the second N-type connector are directly connected and welded with the low-noise amplifier board, which reduces signal loss while achieving ultra-low noise coefficient, greatly improves the sensitivity of the application to receive signals, effectively suppresses out-of-band strong signal interference, ensures stable work in high-rise buildings or complex electromagnetic environments, and the combination design of the shielding cavity and the through-hole capacitor completely eliminates conduction and radiation interference, so that signal transmission is more stable and the effective distance is farther;

[0040] 5、The glass rod-shaped antenna is tightly fixed by the first square support seat and the second square support seat, combined with the solid shell structure, to ensure long-term reliable work in a vehicle vibration environment, thereby improving the structural integrity and connection reliability of the application in a vibration environment;

[0041] 6、The present application realizes three times of cycle processing of "filtering and noise reduction-signal amplification-second filtering and noise reduction" through the multi-stage noise reduction amplification module, breaks through the single noise reduction architecture of "single amplification+single filtering" in the prior art, can gradually deepen the noise suppression effect, improve the accuracy of the signal and improve the adaptability of the present application, the passband range of the filtering circuit in each cycle is gradually narrowed, realizes the progress from broad spectrum noise reduction to accurate noise reduction, significantly improves the noise suppression, and is especially suitable for ADS-B signal reception in a complex electromagnetic environment. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a sectional perspective view of the present application;

[0043] Figure 2 is a sectional perspective view of the present application;

[0044] Figure 3 is a sectional perspective view of the present application;

[0045] Figure 4 is a sectional perspective view of the present application;

[0046] Figure 5 is a sectional perspective view of the present application;

[0047] Figure 6 is a sectional perspective view of the present application.

[0048] In the figure: 1, the shell; 2, the partition plate; 3, the low noise amplifier plate; 4, the first N type connector; 5, the waterproof breather valve; 6, the glass steel rod antenna; 7, the first square support seat; 8, the second square support seat; 9, the second N type connector; 10, the sealing bottom plate; 11, the positioning block. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0050] Please refer to Figures 1-6 , the present application provides an embodiment:

[0051] The utility model provides an ADS-B active antenna, including casing 1 and glass fiber reinforced plastic rod antenna 6, the bottom end of casing 1 is connected with sealing bottom plate 10 through screw, the top end of casing 1 is provided with antenna radiation mechanism for signal reception, the inside of casing 1 is provided with signal connection processing mechanism for signal connection and processing, the bottom end of casing 1 is provided with four groups of mounting holes, when the user installs the utility model, only needs to be through simple tool and bolt to complete the installation work of the utility model, when removing and maintaining the utility model, it is also simple and convenient;

[0052] Please refer to Figures 1-5 In the embodiment, the antenna radiation mechanism includes the first square support seat 7, the second square support seat 8 and the glass fiber reinforced plastic rod antenna 6, the top end of the casing 1 is provided with the glass fiber reinforced plastic rod antenna 6, the top end of the casing 1 is provided with the first square support seat 7, and the first square support seat 7 is located on one side of the glass fiber reinforced plastic rod antenna 6, the top end of the casing 1 is provided with the second square support seat 8 corresponding to the first square support seat 7, and the second square support seat 8 is attached to one side of the first square support seat 7, the corrosion resistance and service life of the glass fiber reinforced plastic rod antenna 6 are improved, and the connection mode of the casing 1, the glass fiber reinforced plastic rod antenna 6, the first square support seat 7 and the second square support seat 8 is a double fixing mode of holding and bottom connection, which constitutes an anti-vibration structure, effectively preventing the glass fiber reinforced plastic rod antenna 6 from loosening or breaking, the glass fiber reinforced plastic rod antenna 6 is located between the first square support seat 7 and the second square support seat 8, the first square support seat 7 and the second square support seat 8 are connected by screws, sealing pads are arranged between the first square support seat 7 and the second square support seat 8, and sealing pads are arranged between the bottom end of the first square support seat 7 and the second square support seat 8 and the casing 1, the sealing property of the utility model is improved, and the user can quickly disassemble and assemble the first square support seat 7 and the second square support seat 8 through screws, achieving quick maintenance;

[0053] Please refer to Figure 3 And Figure 4In the embodiment, the signal connection processing mechanism comprises a partition plate 2, a low-noise amplifier plate 3, a first N-type connector 4 and a second N-type connector 9. The inside of the shell 1 is provided with the partition plate 2. The top end of the partition plate 2 is provided with the low-noise amplifier plate 3, and the top end of the low-noise amplifier plate 3 is attached to the inner wall of the top end of the shell 1. The partition plate 2 and the low-noise amplifier plate 3 are connected to the shell 1 by screws. One end of the shell 1 is connected to the first N-type connector 4 by a screw, and the input end of the first N-type connector 4 is electrically connected to the low-noise amplifier plate 3. The top end of the shell 1 is connected to the second N-type connector 9 electrically connected to the low-noise amplifier plate 3 by a screw. The inner wall of the partition plate 2 and the shell 1 forms an independent shielding cavity. Since the partition plate 2 and the shell 1 are both metal, the sealed metal cavity formed has the effect of shielding signals. The low-noise amplifier plate 3 is located inside the partition plate 2. The top end of the second N-type connector 9 is located inside the glass steel rod-shaped antenna 6. The first N-type connector 4 and the shell 1 are provided with a sealing gasket to improve the sealing performance of the application. The user transmits the first N-type connector 4 to the external ADS-B receiver through the output cable for processing and display. The signals received by the glass steel rod-shaped antenna 6 are transmitted to the low-noise amplifier plate 3 through the second N-type connector 9. The signals are preprocessed and cyclically processed through the low-noise amplifier plate 3. Finally, the processed signals are output through the first N-type connector 4 and transmitted to the user's ADS-B receiver for processing and display. The cyclic processing of the signals is performed at most three times.

[0054] In the embodiment, the low-noise amplifier plate 3 comprises a control unit, a preprocessing unit and a signal processing unit. The control unit comprises an FPGA core processing module for processing real-time data and generating control instructions. The chip model of the FPGA core processing module is XC7K325T, which meets the signal processing requirements. The preprocessing unit comprises a limiter and a filter. The limiter is the first level protection device after the signal enters the low-noise amplifier plate 3, which is used to limit the power amplitude of the input signal. The filter is used to filter out the noise signals outside the passband in advance. The signal processing unit comprises a first-order adaptive filter circuit, a second-order adaptive filter circuit and a third-order adaptive filter circuit, which are respectively used for preliminary filtering, moderate filtering and final filtering of the noise in the preprocessed signal. The noise detection unit is used to collect the noise amplitude of the signal and judge whether the noise meets the threshold of the preset noise error. The noise detection unit adopts a peak detection circuit with a model of AD8461. The noise peak value in the signal cycle is collected as the noise amplitude judgment basis, and the detection accuracy reaches 0.001V.

[0055] The signal processing unit further comprises a first-order low-noise amplification circuit, a second-order low-noise amplification circuit and a third-order low-noise amplification circuit, all of which are used to amplify the noise in the signal processed by the signal preprocessing unit; the first-order low-noise amplification circuit, the second-order low-noise amplification circuit and the third-order low-noise amplification circuit are all provided with an adaptive bias circuit, which adjusts the bias voltage in real time according to the input signal strength of the corresponding amplification circuit, ensures the gain stability of each order of amplification circuit, and avoids signal distortion, the adaptive bias circuit comprises a voltage detection module and an adjustable voltage stabilizing module, which adopts model AD8210 and model LM317, respectively, adjusts the bias voltage in real time according to the input signal strength, the voltage detection module detects the input signal strength of the low-noise amplification module in real time, and adjusts the bias voltage adaptively through the adjustable voltage stabilizing module according to the input signal strength, when the input signal strength is small, the bias voltage is increased, and the gain of the amplification circuit is improved; when the input signal strength is large, the bias voltage is reduced, and the gain of the amplification circuit is reduced, so as to ensure the gain stability of the amplification circuit and avoid signal saturation distortion, the first-order low-noise amplification circuit, the second-order low-noise amplification circuit and the third-order low-noise amplification circuit are constructed by GaAs field effect tube, model ATF-54143, as a prior art GaAs field effect tube refers to a field effect transistor made of gallium arsenide as a semiconductor substrate material, which belongs to a compound semiconductor device and is different from a traditional silicon-based field effect tube; the noise detection unit adopts a peak detection circuit, which takes the noise peak value in the signal cycle as the noise amplitude judgment basis, and the threshold of the preset noise error is adjusted by the upper computer according to the actual application scene, for example, the adjustment range is 0.005V-0.02V; in the complex electromagnetic interference scene such as airport, the threshold is set to 0.005V to improve the noise reduction precision; in the scene with less interference such as open area, the threshold is set to 0.02V to improve the signal processing efficiency; the first-order adaptive filter circuit dynamically adjusts the filter parameters based on the least mean square error algorithm, the convergence speed is set to 0.01, the narrow-band interference noise that is not eliminated in the preliminary filtering is mainly suppressed, and the suppression ability of dynamic interference noise is improved; the second-order adaptive filter circuit adopts an improved least mean square error algorithm, the convergence speed is improved to 0.02, the steady-state error is reduced, and the identification and suppression ability of weak noise is improved; the third-order adaptive filter circuit adopts a crystal filter structure, the passband range is accurately locked to 1089MHz-1091MHz, the final filtering of interference noise is realized, and the weak interference noise close to the ADS-B signal frequency can be effectively filtered out;

[0056] The operation method of the ADS-B active antenna comprises:

[0057] S1: signal preprocessing, receiving and transmitting signals through the glass steel rod antenna 6 and the second N-type connector 9, and pre-processing the signals entering the low noise amplifier board 3 through the limiter and the filter to facilitate subsequent signal processing;

[0058] S2: first cycle processing;

[0059] S2-1: preliminary filtering and noise reduction: the received pre-processed signals are preliminarily filtered through a first-order adaptive filter circuit to filter out high-frequency interference noise outside the 1090MHz core frequency band, the passband range of the first-order adaptive filter circuit is 1085MHz-1095MHz, and the first-order adaptive filter circuit has the characteristics of small insertion loss and flat passband, ensuring the effective preservation of the ADS-B original signal;

[0060] S2-2: signal amplification: the preliminarily filtered signals are input into a first-order low noise amplification circuit, the gain of the first-order low noise amplification circuit is set to 15dB, the noise coefficient is less than 1.5dB, and the signal amplitude is amplified to 0.2V-0.3V, ensuring that the signal strength meets the subsequent processing requirements;

[0061] S2-3: secondary filtering and noise reduction: the amplified signals are filtered again through a first-order adaptive filter circuit, and the convergence speed is set to 0.01, focusing on suppressing narrowband interference noise that has not been eliminated in the preliminary filtering;

[0062] S2-4: noise detection: the noise amplitude of the signal after the first cycle processing is collected by the noise detection unit, and compared with the preset noise error threshold 0.01V, if it is less than the preset noise error threshold, it is output through the first N-type connector 4, if the noise amplitude is greater than the preset noise error threshold, it enters the second cycle processing;

[0063] In the first cycle processing, the gain of the first-order low noise amplification circuit is set to 15dB, at this time the noise coefficient is 1.2dB, the signal amplitude is amplified, the convergence speed of the first-order adaptive filter circuit is 0.01, and the noise amplitude of the filtered signal is reduced to 0.012V, which is greater than the preset threshold 0.01V, and enters the second cycle processing;

[0064] S3: second cycle processing;

[0065] S3-1: moderate filtering and noise reduction: the signal after the first cycle processing is input into a second-order adaptive filter circuit, the passband range of the second-order adaptive filter circuit is narrowed to 1088MHz-1092MHz, and the passband ripple is less than 0.5dB, further filtering out the interference noise at the edge of the frequency band and improving the filter selectivity;

[0066] S3-2: Signal accurate amplification: input the filtered signal of S3-1 into a second-order low-noise amplification circuit, the gain adjustment range is 10dB-20dB, the signal amplitude is amplified to 0.5V-0.6V, and the adaptive bias circuit is set to avoid signal saturation distortion;

[0067] S3-3: Fine filtering and noise reduction: the amplified signal of S3-2 is filtered again through a second-order adaptive filter circuit, the convergence speed is improved to 0.02, the steady-state error is reduced, and the ability to identify and suppress weak noise is improved;

[0068] S3-4: Secondary noise detection: the noise amplitude of the signal is collected again through the noise detection unit, if it is still less than the preset noise error threshold, it is output through the first N-type connector 4, if it is still greater than the preset noise error threshold, it enters the third cycle processing;

[0069] In the second cycle processing, the second-order low-noise amplification circuit adjusts the gain to 12dB according to the input signal strength 0.25V, the signal amplitude is amplified to 0.55V, the convergence speed of the second-order adaptive filter circuit is 0.02, and the noise amplitude of the filtered signal is reduced to 0.011V, which is still greater than the preset threshold;

[0070] S4: Third cycle processing;

[0071] S4-1: Filtering and noise reduction: input the signal after the second cycle processing into a third-order adaptive filter circuit, the passband range is accurately locked to 1089MHz-1091MHz, the interference noise is filtered, and the weak interference noise close to the ADS-B signal frequency can be effectively filtered out;

[0072] S4-2: Signal stable amplification: input the signal processed by S4-1 into a third-order low-noise amplification circuit, with constant gain 10dB, the signal amplitude is amplified to 0.8V-1.0V to ensure the stability of the signal amplitude;

[0073] S4-3: Final filtering and noise reduction: the amplified signal of S4-2 is finally filtered through a third-order adaptive filter circuit;

[0074] S4-4: Final noise detection: collect the noise amplitude of the signal after the third cycle processing to realize the final signal processing;

[0075] In the third cycle processing, the third-order low-noise amplification circuit amplifies the signal amplitude to 0.9V with 10dB constant gain, and the noise amplitude of the filtered signal of the third-order adaptive filter circuit is reduced to 0.008V, and the signal processing is completed at this time;

[0076] S5: output the signal in S4-4 through the first N-type connector 4;

[0077] Need to explain, the bottom end of the shell 1 is uniformly fixedly connected with the positioning block 11, the edge of the sealing bottom plate 10 is uniformly provided with the positioning groove, the positioning block 11 is located in the positioning groove, one side of the shell 1 is connected with the waterproof breather valve 5 through screw thread, the sealing gasket is arranged between the shell 1 and the sealing bottom plate 10 and between the waterproof breather valve 5 and the shell 1, so that the user can quickly disassemble and assemble and the sealing property of the application is improved, the waterproof breather valve 5 is used for balancing the internal and external air pressure of the application, preventing dew formation, when the waterproof breather valve 5 is blocked or fails due to military vehicle paint spraying, maintenance personnel do not need to disassemble the entire device, but can rotate out the old waterproof breather valve 5 by hand or using a simple tool, and replace the new waterproof breather valve 5, which greatly improves the maintenance efficiency, the glass fiber reinforced plastic rod-shaped antenna 6 is tightly held by the first square support seat 7 and the second square support seat 8, the first square support seat 7, the second square support seat 8 and the shell 1 form an anti-vibration structure, effectively preventing the glass fiber reinforced plastic rod-shaped antenna 6 from loosening or breaking, the shielding cavity formed by the partition plate 2 and the inner wall of the shell 1, the low-noise amplifier plate 3 is inside the partition plate 2, which can reduce signal loss while achieving ultra-low noise coefficient, greatly improving the sensitivity of the glass fiber reinforced plastic rod-shaped antenna 6 to receive signals, and reducing the interference of other equipment on the application.

[0078] The working process of the application is as follows:

[0079] Signal receiving: the 1090MHz ADS-B radio frequency signal transmitted by the aerial vehicle is captured by the glass fiber reinforced plastic rod-shaped antenna 6;

[0080] Signal transmission and processing: the captured signal is transmitted to the low-noise amplifier plate 3 through the cable-free direct connection of the first N-type connector 4 with almost no loss, the low-noise amplifier plate 3 pre-processes and circulates the signal, and the signal is circulated at most three times and at least once;

[0081] Signal output: the processed signal is transmitted to the external ADS-B receiver through the output cable;

[0082] Environmental protection: during the entire working process, the multiple sealing structure of the application ensures that the internal circuit is not damaged in a wide temperature range of-40 DEG C to +85 DEG C and high humidity and rain environment, the user can dynamically adjust the internal and external pressure through the waterproof breather valve 5, and the sealing gasket statically blocks the penetration of moisture.

[0083] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference signs in the claims should be considered as limiting the scope of the claims with respect to the figures of the patent document.

Claims

1. An ADS-B active antenna, characterized in that, It includes a housing (1) and a fiberglass rod antenna (6). The bottom end of the housing (1) is connected to a sealing base plate (10) by screws. The top end of the housing (1) is provided with an antenna radiation mechanism for signal reception. The inside of the housing (1) is provided with a signal connection and processing mechanism for signal connection and processing. The bottom end of the housing (1) is provided with four sets of mounting holes. The signal connection processing mechanism includes a low-noise amplifier board (3) and a first N-type connector (4). The antenna radiating mechanism includes a fiberglass rod antenna (6). The low-noise amplifier board (3) includes: The control unit includes an FPGA core processing module, which is used to process real-time data and generate control commands. The preprocessing unit includes a limiter and a filter. The limiter is the first-level protection device after the signal enters the low-noise amplifier board (3) and is used to limit the power amplitude of the input signal. The filter is used to pre-filter out noise signals outside the passband. The signal processing unit includes a first-order adaptive filter circuit, a second-order adaptive filter circuit, and a third-order adaptive filter circuit. The first-order adaptive filter circuit, the second-order adaptive filter circuit, and the third-order adaptive filter circuit are used for preliminary filtering, intermediate filtering, and final filtering of noise in the preprocessed signal, respectively. The noise detection unit is used to collect the noise amplitude of the signal and determine whether the noise meets the preset noise error threshold. The signal processing unit further includes a first-order low-noise amplifier circuit, a second-order low-noise amplifier circuit, and a third-order low-noise amplifier circuit. The first-order low-noise amplifier circuit, the second-order low-noise amplifier circuit, and the third-order low-noise amplifier circuit are all used to amplify the noise in the signal processed by the signal preprocessing unit. The first-order low-noise amplifier circuit, the second-order low-noise amplifier circuit, and the third-order low-noise amplifier circuit are all equipped with an adaptive bias circuit. The adaptive bias circuit adjusts the bias voltage in real time according to the input signal strength of the corresponding amplifier circuit. The first-order low-noise amplifier circuit, the second-order low-noise amplifier circuit, and the third-order low-noise amplifier circuit are constructed using GaAs field-effect transistors. The operation method of the ADS-B active antenna includes: S1: Signal preprocessing, receiving and transmitting signals through the fiberglass rod antenna (6) and the second N-type connector (9), and preprocessing the signals entering the low-noise amplifier board (3) through the limiter and filter; S2: First loop processing; S2-1: Preliminary filtering and noise reduction: The received preprocessed signal is preliminarily filtered by a first-order adaptive filtering circuit; S2-2: Signal Amplification: The pre-filtered signal is input into a first-order low-noise amplifier circuit to amplify the signal amplitude; S2-3: Secondary filtering noise reduction: The amplified signal is filtered again by a first-order adaptive filter circuit to suppress narrowband interference noise that was not eliminated by the initial filtering. S2-4: Noise detection: The noise amplitude of the signal after the first loop processing is collected by the noise detection unit and compared with the preset noise error threshold. If it is less than the preset noise error threshold, it is output through the first N-type connector (4). If the noise amplitude is greater than the preset noise error threshold, it enters the second loop processing. S3: Second loop processing; S3-1: Moderate filtering and noise reduction: The signal after the first loop processing is input into a second-order adaptive filter circuit, and the passband range of the second-order adaptive filter circuit is narrowed. S3-2: Precise signal amplification: The signal filtered by S3-1 is input into a second-order low-noise amplifier circuit to amplify the signal amplitude; S3-3: Fine filtering and noise reduction: The signal amplified by S3-2 is filtered again through a second-order adaptive filtering circuit to improve the ability to identify and suppress weak noise. S3-4: Secondary noise detection: The noise amplitude of the signal is collected again through the noise detection unit. If it is less than the preset noise error threshold, it is output through the first N-type connector (4). If it is still greater than the preset noise error threshold, it enters the third cycle processing. S4: Third loop processing; S4-1: Filtering and noise reduction: Input the signal after the second loop processing into the third-order adaptive filter circuit to lock the passband range; S4-2: Signal Stabilization and Amplification: The signal processed by S4-1 is input into a third-order low-noise amplifier circuit to amplify the signal amplitude; S4-3: Final Filtering and Noise Reduction: The signal amplified by S4-2 is finally filtered by a third-order adaptive filter circuit; S4-4: Final noise detection: Collect the noise amplitude of the signal after the third loop processing to achieve the final signal processing; S5: Output the signal in S4-4 through the first N-type connector (4).

2. The ADS-B active antenna according to claim 1, characterized in that: The bottom end of the housing (1) is uniformly fixedly connected with a positioning block (11), and the edge of the sealing base plate (10) is uniformly provided with a positioning groove. The positioning block (11) is located in the positioning groove. A waterproof and breathable valve (5) is threadedly connected to one side of the housing (1). A sealing gasket is provided between the housing (1) and the sealing base plate (10) and between the waterproof and breathable valve (5) and the housing (1).

3. An ADS-B active antenna according to claim 1, characterized in that: The antenna radiation mechanism further includes a first square support base (7) and a second square support base (8). A fiberglass rod antenna (6) is provided at the top of the housing (1). The first square support base (7) is located on one side of the fiberglass rod antenna (6). The second square support base (8) is located at the top of the housing (1) and corresponds to the first square support base (7). The second square support base (8) is attached to one side of the first square support base (7). The fiberglass rod antenna (6) is located on the first square support base (7). 7) Between the first square support (7) and the second square support (8), the first square support (7) and the second square support (8) are connected by screws. A sealing gasket is provided between the first square support (7) and the second square support (8). A sealing gasket is provided between the bottom of the first square support (7) and the second square support (8) and the housing (1). The fiberglass rod antenna (6) is held tightly by the first square support (7) and the second square support (8). The first square support (7) and the second square support (8) are connected to the top of the housing (1) by screws.

4. An ADS-B active antenna according to claim 3, characterized in that: The signal connection processing mechanism also includes a partition plate (2) and a second N-type connector (9). The partition plate (2) is provided inside the housing (1). A low-noise amplifier board (3) is provided at the top of the partition plate (2), and the top of the low-noise amplifier board (3) is attached to the inner wall of the top of the housing (1). The partition plate (2) and the low-noise amplifier board (3) are connected to the housing (1) by screws. One end of the housing (1) is connected to a first N-type connector (4) by screws, and the input end of the first N-type connector (4) is electrically connected to the low-noise amplifier board (3). The top of the housing (1) is connected to a second N-type connector (9) electrically connected to the low-noise amplifier board (3) by screws. The partition plate (2) and the inner wall of the housing (1) form an independent shielding cavity. The low-noise amplifier board (3) is located inside the partition plate (2). The top of the second N-type connector (9) is located inside the fiberglass rod antenna (6). A sealing gasket is provided between the first N-type connector (4) and the housing (1).

5. An ADS-B active antenna according to claim 4, characterized in that: The noise detection unit uses a peak detection circuit, which uses the noise peak value within the signal period as the basis for judging the noise amplitude. The preset noise error threshold is adjusted by the host computer according to the actual application scenario.

6. An ADS-B active antenna according to claim 5, characterized in that: The first-order adaptive filter circuit dynamically adjusts the filter parameters based on the minimum mean square error algorithm, the second-order adaptive filter circuit adopts an improved minimum mean square error algorithm, and the third-order adaptive filter circuit adopts a crystal filter structure.

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