CN210431363U - Plant protection unmanned aerial vehicle and satellite positioning system and preceding stage amplifier circuit thereof - Google Patents
Plant protection unmanned aerial vehicle and satellite positioning system and preceding stage amplifier circuit thereof Download PDFInfo
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- CN210431363U CN210431363U CN201921640891.1U CN201921640891U CN210431363U CN 210431363 U CN210431363 U CN 210431363U CN 201921640891 U CN201921640891 U CN 201921640891U CN 210431363 U CN210431363 U CN 210431363U
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Abstract
The application discloses plant protection unmanned aerial vehicle and satellite positioning system and preceding stage amplifier circuit thereof, this preceding stage amplifier circuit includes: the double-feed antenna is used for receiving and outputting a first satellite signal and a second satellite signal which have phase difference of 90 degrees; the first preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the first satellite signal; the second preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the second satellite signal; the same-frequency synthesizer is connected with the first preprocessing circuit and the second preprocessing circuit and is used for synthesizing signals to output a first synthesized signal; and the post-processing circuit is connected with the same-frequency synthesizer and is used for filtering, amplifying and outputting the first synthesized signal. By utilizing the high stability and high precision of the double-fed antenna, a series of processing operations such as filtering amplification, signal synthesis, filtering amplification and the like of satellite signals are matched, the signal receiving performance can be effectively improved, and the positioning precision is effectively improved.
Description
Technical Field
The application relates to the technical field of unmanned aerial vehicles, in particular to a plant protection unmanned aerial vehicle and a satellite positioning system and a preceding stage amplifying circuit thereof.
Background
A plant protection unmanned aerial vehicle is an unmanned aerial vehicle for agriculture and forestry plant protection operation, and is mainly positioned by a satellite. After the satellite transmitting positioning signals reach the earth surface through the atmosphere, the positioning system receives and analyzes the signals, and the satellite positioning can be realized through algorithm calculation after at least 4 satellite signals are received.
However, most of the operation areas of the plant protection unmanned aerial vehicle are remote mountainous areas far away from cities, the environment is complex, satellite signals are weak, and therefore the positioning system applied to the plant protection unmanned aerial vehicle is generally difficult to realize accurate positioning, and great troubles are brought to the automatic operation of the plant protection unmanned aerial vehicle.
In view of this, in the prior art, a single-feed antenna amplifier is often used to amplify a satellite signal. However, the positioning accuracy obtained by the single-feed antenna amplifier is still limited, and the single-feed antenna amplifier is suitable for application occasions such as automobile navigation and the like, but the high-accuracy requirement of the plant protection unmanned aerial vehicle cannot be met.
In view of the above, it is an important need for those skilled in the art to provide a solution to the above technical problems.
SUMMERY OF THE UTILITY MODEL
An object of this application is to provide a plant protection unmanned aerial vehicle and satellite positioning system and preceding stage amplifier circuit thereof to effectively improve signal reception performance, and then effectively improve positioning accuracy.
In order to solve the above technical problem, in a first aspect, the present application discloses a preceding stage amplifying circuit of a satellite positioning system, including:
the double-feed antenna is used for receiving and outputting a first satellite signal and a second satellite signal which have phase difference of 90 degrees;
the first preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the first satellite signal;
the second preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the second satellite signal;
the same-frequency synthesizer is connected with the first preprocessing circuit and the second preprocessing circuit and is used for synthesizing signals to output a first synthesized signal;
and the post-processing circuit is connected with the same-frequency synthesizer and is used for filtering, amplifying and outputting the first synthesized signal.
Optionally, the method further comprises:
and the isolation filter is connected with the post-processing circuit and is used for carrying out secondary filtering on the first synthetic signal and carrying out isolation protection on the preceding stage amplifying circuit and a positioning circuit connected behind the preceding stage amplifying circuit.
Optionally, the first preprocessing circuit includes a first band-pass filter and a first low noise amplifier connected in sequence; the second preprocessing circuit comprises a second band-pass filter and a second low-noise amplifier which are sequentially connected; the post-processing circuit comprises a third band-pass filter and a third low-noise amplifier which are sequentially connected.
Optionally, the center frequencies of the first band-pass filter, the second band-pass filter and the third band-pass filter are all 1575.42 MHz.
Optionally, the noise figure of the first low noise amplifier, the second low noise amplifier and the third low noise amplifier is lower than 0.55 dB.
Optionally, the same-frequency synthesizer is a two-input two-output type same-frequency synthesizer, and is configured to output the first synthesized signal and the second synthesized signal, which have a phase difference of 90 degrees and are of a same amplitude, after signal synthesis;
the pre-amplifier circuit further comprises an absorption load for absorbing the second composite signal.
Optionally, the absorption load has a standing wave ratio not higher than 1.25.
Optionally, the absorptive load is a 50 ohm resistance.
In a second aspect, the present application further discloses a satellite positioning system, which includes any one of the preceding stage amplifying circuits described above, and a positioning circuit connected to the preceding stage amplifying circuit in the back.
In a third aspect, the application also discloses a plant protection unmanned aerial vehicle, which comprises the satellite positioning system.
The application provides a satellite positioning system's preceding stage amplifier circuit includes: the double-feed antenna is used for receiving and outputting a first satellite signal and a second satellite signal which have phase difference of 90 degrees; the first preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the first satellite signal; the second preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the second satellite signal; the same-frequency synthesizer is connected with the first preprocessing circuit and the second preprocessing circuit and is used for synthesizing signals to output a first synthesized signal; and the post-processing circuit is connected with the same-frequency synthesizer and is used for filtering, amplifying and outputting the first synthesized signal.
Therefore, the pre-stage amplifying circuit is realized based on the double-fed antenna, and by utilizing the high stability and high precision of the double-fed antenna and matching with a series of processing operations such as filtering amplification, signal synthesis, filtering amplification and the like performed on satellite signals, the signal receiving performance can be effectively improved, and the positioning precision is effectively improved. The plant protection unmanned aerial vehicle that this application provided and satellite positioning system have above-mentioned beneficial effect equally.
Drawings
In order to more clearly illustrate the technical solutions in the prior art and the embodiments of the present application, the drawings that are needed to be used in the description of the prior art and the embodiments of the present application will be briefly described below. Of course, the following description of the drawings related to the embodiments of the present application is only a part of the embodiments of the present application, and it will be obvious to those skilled in the art that other drawings can be obtained from the provided drawings without any creative effort, and the obtained other drawings also belong to the protection scope of the present application.
Fig. 1 is a block diagram of a pre-stage amplifying circuit of a satellite positioning system according to an embodiment of the present disclosure;
fig. 2 is a block diagram of a pre-stage amplifying circuit of a specific satellite positioning system according to an embodiment of the present disclosure;
FIG. 3 is a wiring diagram of a chip of an AFS14A04 bandpass filter disclosed in an embodiment of the present application;
FIG. 4 is a chip wiring diagram of a BGU8019 type low noise amplifier disclosed in the embodiment of the present application;
fig. 5 is a chip wiring diagram of an HPG2F model 3dB bridge disclosed in an embodiment of the present application.
Detailed Description
The utility model provides a plant protection unmanned aerial vehicle and satellite positioning system and preceding stage amplifier circuit thereof lies in providing to effectively improve signal reception performance, and then effectively improve positioning accuracy.
In order to more clearly and completely describe the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The plant protection unmanned aerial vehicle is an unmanned aircraft for agriculture and forestry plant protection operation, and realizes spraying operation such as spraying medicament, seeds, powder and the like through ground remote control or navigation flight control. The plant protection unmanned aerial vehicle realizes automatic control based on the intelligent control system, and determines the position through the positioning system, thereby combining map data to realize automatic operation, and labor cost is saved.
The satellite signal used for positioning the plant protection unmanned aerial vehicle is quite weak in signal intensity after reaching the earth surface through the atmosphere. Under the condition of relatively good environment, the positioning can be easily realized; however, the plant protection unmanned aerial vehicle is mostly applied to remote areas with complex environments and is greatly interfered, so that the situation that signals are lost or even completely cannot be received when a plant protection unmanned aerial vehicle positioning system receives satellite signals frequently causes various problems of unstable positioning, drift, inaccurate position and the like.
Currently, in the prior art, a single-feed antenna amplifier is mostly used to amplify the satellite signal. The single-feed antenna receives the satellite signal, and the amplifier amplifies the satellite signal and then sends the amplified satellite signal to the positioning system for analysis. However, the positioning accuracy of the method still cannot meet the high-accuracy requirement of the plant protection unmanned aerial vehicle. In view of the above, the present application provides a pre-stage amplifying circuit of a satellite positioning system, which can effectively solve the above-mentioned problems.
Referring to fig. 1, an embodiment of the present application discloses a pre-stage amplifying circuit of a satellite positioning system, which mainly includes:
the double-feed antenna 11 is used for receiving and outputting a first satellite signal and a second satellite signal which have phase difference of 90 degrees;
the first preprocessing circuit 12 is connected with the double-fed antenna 11 and used for filtering and amplifying the first satellite signal;
the second preprocessing circuit 13 is connected with the double-fed antenna 11 and is used for filtering and amplifying the second satellite signal;
a same-frequency synthesizer 14 connected to both the first preprocessing circuit 12 and the second preprocessing circuit 13, for performing signal synthesis to output a first synthesized signal;
and the post-processing circuit 15 is connected with the same-frequency synthesizer 14 and is used for filtering, amplifying and outputting the first synthesized signal.
It should be noted that the pre-stage amplifying circuit provided in the embodiment of the present application specifically utilizes the dual-feed antenna 11. The single feed antenna in the prior art only presents circular polarization at a resonance point, when the single feed antenna is used for accessing two satellites such as GPS (1575.42MHz) and GLONASS (1602MHz), a central frequency point is 1590MHz, received GPS signals and GLONASS signals present elliptical polarization, and meanwhile, the two signals also generate cross polarization signals to influence positioning accuracy and deteriorate positioning effect.
The double-fed antenna 11 is provided with two orthogonally-oriented dipoles for receiving signals, can provide full-bandwidth cyclic response for two signals with 90-degree phase offset angles, greatly improves the suppression of cross polarization signals, and can obtain high precision better than that of a single-fed antenna.
After the satellite signals are amplified by the double-fed antenna 11, the first satellite signals can be filtered and amplified by the first preprocessing circuit 12, the second satellite signals can be filtered and amplified by the second preprocessing circuit 13, and then the signals are synthesized by the same-frequency synthesizer 14, namely a 3dB bridge.
The out-of-band noise can be filtered through filtering, and the satellite signal precision is improved. Since the satellite signals received by the dual-feed antenna 11 after transmission are weak, low-noise amplification is required when the first satellite signal and the second satellite signal are amplified, so as to avoid introducing new noise.
The same-frequency synthesizer 14, also called a 3dB bridge, can combine multiple same-frequency signals to improve the utilization rate of output signals, and has the advantages of small insertion loss, high suppression, small in-band fluctuation, large isolation, and small standing-wave ratio. The 3dB electric bridge is adopted to synthesize two paths of satellite signals, so that the axial ratio and the impedance bandwidth of the antenna can be effectively widened, the directional diagram of the antenna is improved, the stability of a phase center is improved, and the positioning precision is further effectively improved.
In the embodiment of the present application, two same-frequency signals with a phase difference of 90 degrees are combined by using a 3dB bridge, and after a first combined signal is output by the same-frequency combiner 14, filtering and amplification are performed again by further using the post-processing circuit 15. Likewise, the amplification in the post-processing circuit 15 may be embodied as low noise amplification.
It should be noted that the total gain of the pre-amplifier circuit should have a certain limit, for example, it cannot exceed 30dB, etc., and those skilled in the art should select and set it according to the practical circuit application scenario.
The embodiment of the application discloses a preceding stage amplifier circuit of satellite positioning system includes: the double-feed antenna 11 is used for receiving and outputting a first satellite signal and a second satellite signal which have phase difference of 90 degrees; the first preprocessing circuit 12 is connected with the double-fed antenna 11 and used for filtering and amplifying the first satellite signal; the second preprocessing circuit 13 is connected with the double-fed antenna 11 and is used for filtering and amplifying the second satellite signal; a same-frequency synthesizer 14 connected to both the first preprocessing circuit 12 and the second preprocessing circuit 13, for performing signal synthesis to output a first synthesized signal; and the post-processing circuit 15 is connected with the same-frequency synthesizer 14 and is used for filtering, amplifying and outputting the first synthesized signal.
Therefore, the pre-stage amplifying circuit is realized based on the double-fed antenna, and by utilizing the high stability and high precision of the double-fed antenna and matching with a series of processing operations such as filtering amplification, signal synthesis, filtering amplification and the like performed on satellite signals, the signal receiving performance can be effectively improved, and the positioning precision is effectively improved.
Referring to fig. 2, an embodiment of the present application discloses a pre-stage amplifying circuit of a specific satellite positioning system.
Further, on the basis of the above, as a specific implementation manner, the pre-stage amplifying circuit of the satellite positioning system disclosed in the embodiment of the present application further includes:
and the isolation filter 16 is connected with the post-processing circuit 15 and is used for carrying out secondary filtering on the first synthesized signal and carrying out isolation protection on the pre-stage amplifying circuit and a subsequent positioning circuit.
Specifically, in the embodiment of the present application, the isolation filter 16 is disposed at the output end of the pre-stage amplification circuit, on one hand, the harmonic generated in the signal amplification process of the post-processing circuit 15 can be filtered again through filtering, and on the other hand, the pre-stage amplification circuit can be isolated from the post-positioning circuit, so as to prevent the pre-stage amplification circuit and the post-positioning circuit from generating self-excited crosstalk. Further, the total gain of the pre-amplifier circuit can be controlled by the band-pass filter 4.
Further, on the basis of the above content, in the pre-stage amplifying circuit of the satellite positioning system disclosed in the embodiment of the present application, the first preprocessing circuit 12 includes a first band-pass filter and a first low noise amplifier, which are connected in sequence; the second preprocessing circuit 13 includes a second band-pass filter and a second low noise amplifier connected in sequence; the post-processing circuit 15 includes a third band-pass filter and a third low noise amplifier connected in series.
As a specific example, the center frequencies of the first band-pass filter, the second band-pass filter and the third band-pass filter may be 1575.42 MHz. For example, a bandpass filter of AFS14a04 model manufactured by abracon corporation may be specifically used, the insertion loss of the bandpass filter is 0.8dB, the out-of-band rejection is greater than 40dBm, the low loss is ensured, the high rejection degree of noise is realized, and various indexes of the signal receiving system can be effectively improved. Moreover, the band-pass filter adopts the packaging specification of 1.1 x 1.4mm, so that the design space of a circuit on the plant protection unmanned aerial vehicle is saved.
Referring to fig. 3, fig. 3 is a chip wiring diagram of an AFS14a04 model bandpass filter. As shown in FIG. 3, the chip can be used conveniently, and can work normally only by connecting coupling capacitors C1 and C2 to the input end and the output end of the chip and ensuring good grounding performance.
Further, on the basis of the above, in the pre-stage amplifying circuit of the satellite positioning system disclosed in the embodiment of the present application, the noise coefficients of the first low noise amplifier, the second low noise amplifier and the third low noise amplifier are all lower than 0.55 dB.
Since the noise of the amplifier may seriously interfere with the signal in the process of amplifying the weak signal, the signal-to-noise ratio of the output signal can be further improved by using a low-noise amplifier (low-noise amplifier). Low noise amplifiers, i.e., amplifiers with very low noise figure, are commonly used as high or intermediate frequency preamplifiers in various types of radio receivers, as well as amplification circuits in high sensitivity electronic detection devices.
Modern low noise amplifiers mostly adopt transistors and field effect transistors; the microwave low noise amplifier adopts a variable capacitance diode parametric amplifier. The noise figure F of an ideal amplifier is 1(0 db), which has the physical meaning that the input signal-to-noise ratio is equal to the output signal-to-noise ratio; in practical applications, a well-designed low noise amplifier can generally reach less than 3 db.
Specifically, the low noise amplifier may specifically be a BGU8019 low noise amplifier from enzima corporation, whose noise figure is as low as 0.55dB, and only a small noise is introduced in the process of amplifying satellite signals; meanwhile, the amplifier has low power consumption, the working frequency is controlled to be 1559MHz to 1610MHz, the gain can reach 18dB, and the gain for out-of-band signals is relatively small. The BGU8019 is packaged by SOT1232, is only 1.1 × 0.7mm in size, and normally works under the voltage of 1.5V to 3V and the working current is 4.6 mA.
Referring to fig. 4, fig. 4 is a chip wiring diagram of a BGU8019 type low noise amplifier. IN use, as shown IN fig. 4, pi-type filtering may be applied at the power supply pin VCC of the lna to prevent interference from external signals, and a 6.8nH inductor may be coupled at the input pin RF _ IN to match the absorptive load 17.
Further, on the basis of the above content, in the pre-stage amplifying circuit of the satellite positioning system disclosed in the embodiment of the present application, the same-frequency synthesizer 14 is a two-in two-out type same-frequency synthesizer, and is configured to output the first synthesized signal and the second synthesized signal that have a phase difference of 90 degrees and are of the same amplitude after signal synthesis; the pre-amplifier circuit further comprises an absorption load 17 for absorbing the second combined signal.
Specifically, a 3dB bridge model of HPG2F manufactured by EMC rflab corporation may be selected, the bridge having an insertion loss of 0.3dB, a minimum isolation of 22dB, and a phase balance of 90 ° ± 3 °.
Referring to fig. 5, fig. 5 is a chip wiring diagram of an HPG2F model 3dB bridge. As shown in fig. 5, the model HPG2F has two output terminals for outputting two synthesized signals, respectively, in this embodiment, only the first synthesized signal output by the output terminal J1 is needed, and the second synthesized signal output by the other output terminal J2 can be absorbed by the absorption load 17, so as to prevent the standing wave ratio of the other port from being affected by the signal reflection.
Wherein, as a specific example, the standing wave ratio of the absorption load 17 is not higher than 1.25. Further, the absorption load 17 may be specifically a resistance of 50 ohms. The 50 ohm load acts as an absorbing load 17 for the 3dB bridge, and the free output is grounded through the load, thereby absorbing the second composite signal.
Specifically, the absorption load 17 may specifically be an SMT1206ALNF type load of EMC rflab corporation, and the load operates in a DC-2.7G frequency band, has a maximum standing-wave ratio of 1.25, and can effectively absorb a signal at the port.
Furthermore, the application also discloses a satellite positioning system, which comprises any one of the preceding stage amplifying circuits and a positioning circuit connected with the preceding stage amplifying circuit in a backward mode.
Further, this application still discloses a plant protection unmanned aerial vehicle, includes as above satellite positioning system.
For specific contents of the plant protection unmanned aerial vehicle and the satellite positioning system, reference may be made to the detailed description of the pre-amplification circuit of the satellite positioning system, and details thereof are not repeated here.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the equipment disclosed by the embodiment, the description is relatively simple because the equipment corresponds to the method disclosed by the embodiment, and the relevant parts can be referred to the method part for description.
It is further noted that, throughout this document, relational terms such as "first" and "second" are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The technical solutions provided by the present application are described in detail above. The principles and embodiments of the present application are explained herein using specific examples, which are provided only to help understand the method and the core idea of the present application. It should be noted that, for those skilled in the art, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall into the protection scope of the present application.
Claims (10)
1. A preamplifier circuit for a satellite positioning system, comprising:
the double-feed antenna is used for receiving and outputting a first satellite signal and a second satellite signal which have phase difference of 90 degrees;
the first preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the first satellite signal;
the second preprocessing circuit is connected with the double-fed antenna and used for filtering and amplifying the second satellite signal;
the same-frequency synthesizer is connected with the first preprocessing circuit and the second preprocessing circuit and is used for synthesizing signals to output a first synthesized signal;
and the post-processing circuit is connected with the same-frequency synthesizer and is used for filtering, amplifying and outputting the first synthesized signal.
2. The preamplifier circuit according to claim 1, further comprising:
and the isolation filter is connected with the post-processing circuit and is used for carrying out secondary filtering on the first synthetic signal and carrying out isolation protection on the preceding stage amplifying circuit and a positioning circuit connected behind the preceding stage amplifying circuit.
3. The preamplifier circuit according to claim 1,
the first preprocessing circuit comprises a first band-pass filter and a first low-noise amplifier which are sequentially connected;
the second preprocessing circuit comprises a second band-pass filter and a second low-noise amplifier which are sequentially connected;
the post-processing circuit comprises a third band-pass filter and a third low-noise amplifier which are sequentially connected.
4. The preamplifier circuit according to claim 3, wherein the first, second and third bandpass filters each have a center frequency of 1575.42 MHz.
5. The preamplifier circuit according to claim 3, wherein the noise figure of each of the first, second and third low noise amplifiers is lower than 0.55 dB.
6. The preamplifier circuit according to any of claims 1 to 5, wherein the same-frequency synthesizer is a two-in two-out type same-frequency synthesizer, and is configured to output the first synthesized signal and the second synthesized signal, which have a phase difference of 90 degrees and a same amplitude, after signal synthesis;
the pre-amplifier circuit further comprises an absorption load for absorbing the second composite signal.
7. The preamplifier circuit according to claim 6, wherein the absorption load has a standing wave ratio not higher than 1.25.
8. The preamplifier circuit of claim 7, wherein the absorptive load is a 50 ohm resistor.
9. A satellite positioning system comprising a preamplifier circuit according to any of claims 1 to 8, and a positioning circuit connected downstream of the preamplifier circuit.
10. A plant protection drone, characterized in that it comprises a satellite positioning system according to claim 9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921640891.1U CN210431363U (en) | 2019-09-27 | 2019-09-27 | Plant protection unmanned aerial vehicle and satellite positioning system and preceding stage amplifier circuit thereof |
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| CN201921640891.1U CN210431363U (en) | 2019-09-27 | 2019-09-27 | Plant protection unmanned aerial vehicle and satellite positioning system and preceding stage amplifier circuit thereof |
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