Electromagnetic interference solving system for radio imaging telescope in extreme electromagnetic environment

Abstract

The invention discloses a system for solving electromagnetic interference of a radio imaging telescope in an extreme electromagnetic environment. The system comprises a shielding and filtering integrated assembly, a combined filter, a resolver filter, a limiting filter, a motor shielding case and a resolver shielding case, the shielding and filtering integrated assembly is installed at an external interface of the servo drive control box, the combined filter is installed at an interface of an azimuth motor and a pitching motor, the rotary transformer filter is installed at an interface of a pitching rotary transformer and an azimuth rotary transformer, and the limiting filter is installed at an interface of a pitching limiting device and an azimuth limiting device. Wherein the azimuth motor and the pitching motor are respectively provided with a motor shielding case, and the pitching rotary transformer and the azimuth rotary transformer are respectively provided with a rotary transformer shielding case.

Description

Technical Field

[0001] The invention belongs to the field of astronomical observation systems, and in particular relates to a system for solving electromagnetic interference of a radio imaging telescope in an extreme electromagnetic environment. Background Art

[0002] During the site selection process, the radio imaging telescope will evaluate the impact of surrounding fixed and mobile interference sources on astronomical observations, but the operation of the telescope's own system will also generate electromagnetic interference, and this part of the solution is quite difficult. The electromagnetic interference generated by the operation of the radio imaging telescope system itself has an impact on the results of astronomical observations. Radio imaging telescopes are usually composed of multiple antennas of the same diameter, which are evenly distributed on a ring of a certain diameter. There is a calibration tower in the center of the ring to provide a calibration benchmark for the entire observation link. All antennas in the system need to be controlled by the drive system to keep their centers facing the observed celestial body at all times, which means that the servo drive system is always working and will inevitably generate electromagnetic interference. In order to ensure that astronomical observations are not affected, during the operation of the servo drive system of a single antenna, within the selected observation frequency band, the level of the RF signal received by the antenna must be controlled below a certain power, so it is necessary to suppress the electromagnetic interference of the product during the operation of the servo drive system.

[0003] The on-site environment of existing radio imaging telescopes usually has four factors: "humid environment factors", "end-to-end position factors" of multiple antennas, "long-term factors" of astronomical observations, and "online timeliness factors" of interference detection. During the electromagnetic reinforcement process, the measures taken must ensure that the suppression effect is obvious and stable and effective in the long term. Summary of the invention

[0004] The present invention aims to solve the technical problems existing in the background technology and to provide a system for solving electromagnetic interference of radio imaging telescopes in extreme electromagnetic environments.

[0005] In order to solve the technical problem, the technical solution of the present invention is:

[0006] A system for solving electromagnetic interference of a radio imaging telescope in an extreme electromagnetic environment, the system comprising: a shielding and filtering integrated component, a combined filter, a resolver filter, a limiting filter, a motor shielding cover and a resolver shielding cover;

[0007] The shielding filter integrated component is installed at the external interface of the servo drive control box, the combined filter is installed at the interface between the azimuth motor and the pitch motor, the resolver filter is installed at the interface between the pitch resolver and the azimuth resolver, and the limit filter is installed at the interface between the pitch limit and the azimuth limit;

[0008] Wherein, the azimuth motor and the pitch motor are both installed with motor shielding covers, and the pitch resolver and the azimuth resolver are both installed with resolver shielding covers.

[0009] Furthermore, the limit filter adopts a limit switch filter, and the combined filter includes: multiple motor drive filters and motor encoding filters; the shielding filter integrated component is electrically connected to multiple resolver filters, multiple limit filters and the combined filter.

[0010] Furthermore, the azimuth motor adopts a large disk motor, and the pitch motor includes: a right ascension motor and a declination motor; the pitch rotation is a right ascension rotation and a declination rotation, and the azimuth rotation is a large disk rotation.

[0011] Furthermore, the shielding and filtering integrated component is connected to the limit switch filter through the large disk limit switch cable connection connector, and the limit switch filter is connected to the limit switch through the connector;

[0012] The shielding and filtering integrated component is connected to the motor drive filter through the large-disk motor drive cable and the connector, and the motor drive filter is connected to the large-disk motor through the connector;

[0013] The shielding and filtering integrated assembly is connected to the large disc motor via a large disc motor brake cable;

[0014] The shielding and filtering integrated component is connected to the motor encoding filter through the large-plate motor encoding cable connection connector, and the motor encoding filter is connected to the large-plate motor through the connector;

[0015] The shielding and filtering integrated component is connected to the resolver filter through a large-disc resolver cable connected to a connector, and the resolver filter is connected to the large-disc resolver through a connector;

[0016] The shielding and filtering integrated component is connected to the motor encoder filter through the right ascension motor encoding cable connection connector, and the motor encoder filter is connected to the right ascension motor through the connector;

[0017] The shielding and filtering integrated assembly is connected to the right ascension motor via the right ascension motor brake cable;

[0018] The shielding and filtering integrated component is connected to the motor drive filter through the right ascension motor drive cable and the connector, and the motor drive filter is connected to the right ascension motor through the connector;

[0019] The shielding and filtering integrated component is connected to the limit switch filter through the right ascension limit switch cable and the connector, and the limit switch filter is connected to the limit switch through the connector;

[0020] The shielding and filtering integrated component is connected to the motor drive filter after being connected to the connector via the declination motor drive cable, and the motor drive filter is connected to the declination motor via the connector;

[0021] The shielding and filtering integrated component is connected to the resolver filter via a right ascension resolver cable connected to a connector, and the resolver filter is connected to the declination resolver via a connector;

[0022] The shielding and filtering integrated assembly is connected to the declination motor via a declination motor brake cable;

[0023] The shielding and filtering integrated component is connected to the limit switch filter through the declination motor switch cable connection connector, and the limit switch filter is connected to the declination motor through the connector;

[0024] The shielding and filtering integrated component is connected to the motor encoding filter through the declination motor encoding cable connection connector, and the motor encoding filter is connected to the limit switch through the connector;

[0025] The shielding and filtering integrated component is connected to the resolver filter via a declination resolver cable connection connector, and the resolver filter is connected to the declination resolver via a connector.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] 1. Comprehensive electromagnetic interference protection: The system design includes multi-level electromagnetic interference filters (such as limit filters, combination filters and resolver filters), which effectively reduce electromagnetic interference from different sources and ensure the observation accuracy of the radio imaging telescope.

[0028] 2. System integration: The integrated shielding and filtering components integrate multiple filtering functions, simplify the system structure, facilitate installation and maintenance, and improve the stability and reliability of the system.

[0029] 3. Adapt to extreme electromagnetic environment: This system is specially designed for the extreme electromagnetic environment in the field of radio astronomy. It can effectively deal with various electromagnetic interferences and ensure the continuity and accuracy of observation work.

[0030] 4. Effectiveness of electromagnetic shielding: The application of motor shielding cover and resolver shielding cover enhances the electromagnetic compatibility between electrical components and reduces the impact of interference generated by motors and resolvers on other equipment.

[0031] 5. Modular design: The modular design of each filter and shielding device makes the system more flexible, convenient for later upgrades and expansions, and adapts to different application requirements.

[0032] 6. Multi-motor electromagnetic suppression: The system covers a variety of configurations of large-disk motors, right ascension motors and declination motors, which can meet the movement requirements of different angles and directions while effectively controlling the electromagnetic interference, thereby improving the flexibility, precise control capability and good electromagnetic compatibility of the telescope.

[0033] 7. Comprehensive connection solution: Through a series of connectors and cables, the connection between each functional module is efficient and clear, ensuring the stability and integrity of signal transmission.

[0034] In summary, the present invention effectively solves the electromagnetic interference problem through a multi-level protection design and a modular processing solution, provides protection for radio imaging telescopes in extreme electromagnetic environments, and thus improves the accuracy and reliability of astronomical observation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 , a main framework diagram of a system for solving electromagnetic interference of a radio imaging telescope in an extreme electromagnetic environment according to the present invention;

[0036] Figure 2 , the electromagnetic reinforcement schematic diagram of the antenna unit turntable servo system;

[0037] Figure 3 , is a schematic diagram of the shielding and filtering integrated component 1 of the ADU;

[0038] Figure 4 , the explosion diagram of the final improved large disk / right ascension / declination resolver shielding and filtering integrated device;

[0039] Figure 5 , the final improved resolver shield model (from left to right: large disk, right ascension and declination);

[0040] Figure 6 , Schematic diagram of motor cover shielding rectification;

[0041] Figure 7 , Schematic diagram of the shielding rectification at the tail of the connector inside the motor cover;

[0042] Figure 8 , power supply filter circuit;

[0043] Fig. 9 , signal filtering circuit. DETAILED DESCRIPTION

[0044] The specific implementation mode of the present invention is described below in conjunction with embodiments:

[0045] It should be noted that the structures, proportions, sizes, etc. shown in this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0046] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0047] Embodiment 1:

[0048] The antenna is controlled by the servo drive system to keep its center following the movement of the sun. The servo drive system mainly includes the servo drive control box, motor, rotary encoder, limit switch, etc. The servo drive control box, motor and rotary encoder are the main interference sources. They will generate electromagnetic interference during their operation, affecting the results of astronomical observations. The following method is used to solve the electromagnetic interference.

[0049] like Figure 1 As shown, when the drive control box is working, signals of various frequencies are transmitted and transmitted through cables, causing electromagnetic interference to the outside. Installing an integrated shielding and filtering component at the external interface of the drive control box can reduce electromagnetic interference. The motor, resolver, limit switch, etc. will also generate interference and radiate through the cable. Therefore, it is necessary to add filters to their interfaces to reduce cable conduction and emission. Due to the extremely strict requirements on the background noise required for astronomical observation environments, all interconnected cables need to be double-shielded, and shielding covers must be installed on components that cannot achieve self-shielding. The specific installation system diagram is as follows Figure 2 shown.

[0050] Integrated shielding and filtering components in the ADU chassis (servo drive control box):

[0051] The appearance of the shielding and filtering integrated component 1 of the ADU input / output interconnection port is as follows Figure 3 As shown. The application in ADU ensures the filtering (see Table 1) and integrated isolation of different signals (frequency bands). It suppresses the high-frequency conduction interference of the drive output frequency and its frequency multiplication of the ADU external lead wire, as well as the high-frequency clock and clock frequency multiplication signal generated by digital processing, and reduces the high-frequency noise potential of the servo drive system plug-in cable at the ADU end.

[0052] Table 1 - Signal filtering of antenna servo drive system ADU shielding filter integrated panel 1

[0053]

[0054] Altitude / right ascension / declination motor drive filters: suppress broadband high-frequency conducted interference at multiples of the cable 1 drive frequency on the motor input side.

[0055] Pan / RA / Declination motor limit switch filter: suppresses the antenna radiation effect of high-frequency conducted interference from the 8-meter-long cable leading out of the ADU side limit.

[0056] Large disk / right ascension / declination motor encoder filter: The final improved large disk / right ascension / declination motor encoder filter models are filters with the same structure, which are used to suppress broadband high-frequency conducted interference of encoder digital / pulse signals.

[0057] The integrated shielding and filtering device for the large disk / right ascension / declination resolver: The electromagnetic leakage suppression of the large disk / right ascension / declination resolver is finally adopted. The structure of the shielding and filtering integrated device is as follows Figure 4 The device provides shielding for the resolver structure and suppresses high-frequency conducted interference of the resolver operating frequency and its multiples.

[0058] The final improved integrated structure of the three resolvers is as follows: Figure 5 shown.

[0059] Interconnection cable: The lead-out cable at the ADU end of the antenna unit is a shielded cable. A conductive cloth layer is added to the outer layer of the cable, and the connector tail of the cable is reliably conductively connected to the metal shielding layer and the conductive cloth shielding layer at 360 degrees.

[0060] Motor shielding cover modification: 360° shielding installation of motor shielding shell and cover plate, and reliable shielding fixation of connector on shielding cover.

[0061] Implementation: Figure 6 As shown, the key points are as follows:

[0062] The overlapping surface has good conductivity (shielding shell and cover plate, conductive gasket are free of rust);

[0063] Ensure that the edge of the cover plate is in continuous contact with the conductive pad at 360°;

[0064] The lateral locking of the motor shielding shell and the cover can provide positive pre-tightening force to the gasket to ensure that the shell and the cover form a shielding body. If the shielding of the motor shielding shell and the cover is not in place, it is necessary to paste conductive copper foil around the gap of the overlapping surface of the shielding shell and the cover as a remedial measure.

[0065] The connector is conductively connected to the panel shield and is securely fixed. The connection between the connector and the shielding cover is not allowed to become loose during external cable insertion.

[0066] Corrective requirement 2: The three connectors in the motor shielding cover must have a 360° reliable shielding overlap with the shielding layer at the end of the cable.

[0067] Implementation: Figure 7 As shown: the shielding layer of the three connector cables and the tail of the connector are 360° reliably shielded and overlapped. The treatment method for the tail of the three connector cables is the same: the specific steps are as follows: (see the implementation process below)

[0068] First, fix the connector on the panel and make sure the screws of the cable locking piece at the rear of the connector are in the removable position.

[0069] Remove the cable lock at the end of the connector and clean off the original shield overlap (shield braid accumulation).

[0070] Evenly wrap the copper mesh on the original braided layer of the cable until the outer diameter of the copper mesh is 1mm larger than the diameter of the pressure plate hole, remove the excess copper mesh, and push the edge of the copper mesh into the inner hole of the connector. Use the tail cable locking piece to lock the wrapped copper mesh to the tail of the connector.

[0071] Use conductive cloth tape to shield and prevent the wrapped copper mesh connector and the connector tail from loosening.

[0072] Repeat the previous step with conductive tape to reinforce the shielding of the connector tail and the overall anti-twisting reinforcement of the connector tail and the insulation layer.

[0073] Embodiment 2:

[0074] The selection of resolver filter, limit filter and combined filter is as follows:

[0075] Passive filter circuits are designed using analog filters. Typical analog filter functions include Butterworth filter function, Chebyshev filter function, elliptic filter function, and Bessel filter function. The characteristics of several filter functions are as follows:

[0076] Butterworth filter function: has a monotonically decreasing amplitude-frequency characteristic and the flattest stop band;

[0077] Chebyshev filter function: The amplitude-frequency characteristic fluctuates in the passband or stopband, the stopband drops quickly, but the cutoff rate is fast, which can improve frequency selectivity;

[0078] Bessel filter function: has good linearity and phase characteristics within the passband, but poor frequency selection characteristics of the amplitude-frequency characteristic;

[0079] Elliptical filter function: the passband has fluctuations, the stopband is relatively flat, but it drops the fastest.

[0080] Since the primary principle of the design requirement is that the normal transmission signal in the passband should be as unaffected as possible and the attenuation in the stopband should be large, and the stopband of the Butterworth filter function presents the flattest characteristic, this project chooses the Butterworth filter function model to design the passive low-pass filter circuit.

[0081] For passive filters, impedance mismatch is an important design principle that causes insertion loss, selects component types and parameters in the filter circuit, and suppresses conducted electromagnetic interference. In actual engineering design, the input and output (source and load) impedances of passive filters are usually equivalent to 50Ω. Since this filter involves precise design, it is necessary to analyze and estimate the impedance of the source and load ends according to the power supply characteristics to be suppressed, so as to further accurately determine the possible source and load impedances.

[0082] General principle of impedance mismatch: In the frequency range to be filtered, according to the source impedance and load impedance at the input and output of the filter, select the topology of the filter circuit according to the impedance mismatch principle in Table 1.

[0083] Table 1 - Impedance mismatch principles

[0084]

[0085] As can be seen from Table 1, when the source impedance or load is low impedance (usually reflected as capacitance), an inductor is selected in series with it; when the source impedance or load is high impedance (usually reflected as inductance), a capacitor is selected in parallel with it.

[0086] The power interface is designed with a derating design, and the corresponding derating design is adopted according to different power capacities. In particular, the large current filter components use a lower derating factor to ensure the safe and reliable operation of the power circuit. In view of the characteristics of a large number of signal interfaces, a wide operating frequency band, and a high transmission rate, a matching filter circuit is designed based on the cutoff frequency of different signals while ensuring signal integrity. In addition, in view of the strong mutual coupling problem caused by the different insertion loss cutoff frequencies of each signal port, an integrated filter-shielding design is adopted to meet the shielding effect requirements of the equipment in an interconnected working state.

[0087] like Figure 8 As shown, the power filter circuit selects two-stage filtering, the inductance of the common-mode inductor Lc is at least in the mH level, the capacitance of the differential-mode capacitor Cx is at least in the uF level, and the common-mode capacitor is at least in the nF level, which can simultaneously meet the high insertion loss of high frequency and low frequency; Fig. 9 As shown in the figure, the filtering of the signal line is to suppress the common mode interference on the cable. The cut-off frequency of the signal is mainly considered during design. The cut-off frequency is generally 10 or 20 times the operating frequency. When selecting capacitors, the capacitors have no insertion loss or the insertion loss value is ≤3dB at the cut-off frequency of the signal to ensure the integrity of the signal transmission.

[0088] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

[0089] Many other changes and modifications may be made without departing from the concept and scope of the present invention.It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A system for solving electromagnetic interference of radio imaging telescopes in extreme electromagnetic environments, characterized in that: The system comprises: a shielding and filtering integrated component, a combined filter, a resolver filter, a limit filter, a motor shielding cover and a resolver shielding cover; The shielding filter integrated component is installed at the external interface of the servo drive control box, the combined filter is installed at the interface between the azimuth motor and the pitch motor, the resolver filter is installed at the interface between the pitch resolver and the azimuth resolver, and the limit filter is installed at the interface between the pitch limit and the azimuth limit; Wherein, the azimuth motor and the pitch motor are both installed with motor shielding covers, and the pitch resolver and the azimuth resolver are both installed with resolver shielding covers.

2. The electromagnetic interference resolution system for radio imaging telescopes in extreme electromagnetic environments according to claim 1, characterized in that: The limit filter adopts a limit switch filter, and the combined filter includes: multiple motor drive filters and motor encoding filters; the shielding filter integrated component is electrically connected to multiple resolver filters, multiple limit filters and the combined filter.

3. The electromagnetic interference resolution system for radio imaging telescopes in extreme electromagnetic environments according to claim 2, characterized in that: The azimuth motor adopts a large disk motor, and the pitch motor includes: a right ascension motor and a declination motor; the pitch rotation is a right ascension rotation and a declination rotation, and the azimuth rotation is a large disk rotation.

4. The electromagnetic interference resolution system for radio imaging telescopes in extreme electromagnetic environments according to claim 3, characterized in that: The shielding and filtering integrated component is connected to the limit switch filter through the large disk limit switch cable connection connector, and the limit switch filter is connected to the limit switch through the connector; The shielding and filtering integrated component is connected to the motor drive filter through the large-disk motor drive cable and the connector, and the motor drive filter is connected to the large-disk motor through the connector; The shielding and filtering integrated assembly is connected to the large disc motor via a large disc motor brake cable; The shielding and filtering integrated component is connected to the motor encoding filter through the large-plate motor encoding cable connection connector, and the motor encoding filter is connected to the large-plate motor through the connector; The shielding and filtering integrated component is connected to the resolver filter through a large-disc resolver cable connected to a connector, and the resolver filter is connected to the large-disc resolver through a connector; The shielding and filtering integrated component is connected to the motor encoder filter through the right ascension motor encoding cable connection connector, and the motor encoder filter is connected to the right ascension motor through the connector; The shielding and filtering integrated assembly is connected to the right ascension motor via the right ascension motor brake cable; The shielding and filtering integrated component is connected to the motor drive filter through the right ascension motor drive cable and the connector, and the motor drive filter is connected to the right ascension motor through the connector; The shielding and filtering integrated component is connected to the limit switch filter through the right ascension limit switch cable and the connector, and the limit switch filter is connected to the limit switch through the connector; The shielding and filtering integrated component is connected to the motor drive filter after being connected to the connector via the declination motor drive cable, and the motor drive filter is connected to the declination motor via the connector; The shielding and filtering integrated component is connected to the resolver filter via a right ascension resolver cable connected to a connector, and the resolver filter is connected to the declination resolver via a connector; The shielding and filtering integrated assembly is connected to the declination motor via a declination motor brake cable; The shielding and filtering integrated component is connected to the limit switch filter through the declination motor switch cable connection connector, and the limit switch filter is connected to the declination motor through the connector; The shielding and filtering integrated component is connected to the motor encoding filter through the declination motor encoding cable connection connector, and the motor encoding filter is connected to the limit switch through the connector; The shielding and filtering integrated component is connected to the resolver filter via a declination resolver cable connection connector, and the resolver filter is connected to the declination resolver via a connector.

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