1. An EMC analysis model and an EMC characteristic improvement method for a communication load of a sky-start constellation are characterized by comprising the following steps:

aiming at load radiation disturbance, an EMC analysis model of the load of the launch satellite is established, the EMC analysis model comprises a load cabin, a load structure cabin arranged in the load cabin and a load antenna connected to the load structure cabin, and the following parameters are set:

R₀natural noise and interference signals entering the load antenna from the outside;

c: the conductivity coefficient of a coaxial radio frequency cable between the load antenna and the load;

g: a load path gain;

R_d: the radiation coefficient of the DCS load to the satellite interference signal;

R_s: radiation coefficient of interference signals of the star body to the load antenna;

E_d: the shielding factor of the load carrying structural compartment,

E_s: shielding coefficient of the satellite load compartment;

determining the noise bottom N of the load receiving channel under the ideal condition according to the load EMC analysis model₀Comprises the following steps: n is a radical of₀＝R₀+ C + G; (for ease of calculation, units are in decibels, i.e. dB)

Determining the interference of the noise bottom after radiation coupling back to the load antenna as follows:

N₁＝[(N₀-E_d)*R_d-E_s]*R_s+C+G；

the same principle is as follows:

N_i＝[(N_i-1-E_d)*R_d-E_s]*R_s+C+G，

wherein: i is a natural number, N_iInterference that is radiatively coupled back to the loaded antenna the ith time.

Thus, the actual load receive channel noise floor is determined as:

2. the EMC analysis model and EMC characteristic improvement method of the launch constellation communication load of claim 1, wherein the EMC characteristic is improved by reducing one or more of a coaxial radio frequency cable conduction coefficient between the load antenna and the load, a load channel gain, a radiation coefficient of DCS load to satellite interference signals, and a radiation coefficient of satellite to load antenna interference signals.

3. The method for improving EMC analysis model and EMC characteristics of the sky constellation communication load according to claim 1 or 2, wherein EMC characteristics are improved by increasing shielding coefficients of the load structure cabin and/or shielding coefficients of the star load cabin.

4. The EMC analysis model and EMC characteristic improvement method of the sky constellation communication load according to claim 1 or 2, characterized in that the coaxial radio frequency cable conduction coefficient between the load antenna and the load is a fixed value.

5. The method for improving the EMC analysis model and the EMC characteristics of the sky constellation communication load according to claim 1 or 2, wherein the radiation coefficient of interference signals of DCS load to a star is reduced by attaching a wave absorbing material inside the load cabin.

6. The method for improving EMC analysis model and EMC characteristics of the sky constellation communication load according to claim 1 or 2, wherein the shielding coefficient of the load structure cabin is increased by adding shielding materials.

7. The method for improving EMC analysis model and EMC characteristics of the sky constellation communication load according to claim 1 or 2, wherein the shielding coefficient of the star load chamber is increased by adding shielding materials.

8. The method for improving EMC (electromagnetic compatibility) characteristics of the sky constellation communication load EMC analysis model and the EMC characteristics as claimed in claim 1 or 2, wherein the EMC characteristics are improved by wrapping the load connector gaps and the structural gaps with shielding materials.

9. The Endoable constellation communication load EMC analysis model and EMC characteristic improvement method of claim 1 or 2, wherein EMC characteristics are improved by shielding load supply lines and data lines.

10. The EMC analysis model and EMC characteristic improvement method of the sky constellation communication load according to claim 1 or 2, wherein the EMC characteristic is improved by wrapping holes of the satellite load cabin plate through cables with shielding materials.

Background

The communication frequency of the satellite Internet of things mainly works in a VHF frequency band (30 MHz-300 MHz, the wavelength is 1 m-10 m) and a UHF frequency band (300 MHz-3 GHz, the wavelength is 1 m-0.1 m), but the uplink and downlink frequency bands are greatly interfered, and the communication frequency mainly shows noise bottom elevation and high-power burst interference.

The sky-start satellite is used as an internet-of-things satellite and has the characteristics of low transmitting power, low signal-to-noise ratio of received signals, less level allowance of a communication link and the like. In recent years, with the rapid increase of military frequency equipment and civil radio equipment and systems, the electromagnetic environment of the space on-orbit satellite presents a situation of increasing complexity, the incompatibility problems of electromagnetic self-interference, mutual interference and the like are increased gradually, and higher electromagnetic compatibility requirements are provided for the space on-orbit satellite and the load thereof.

On the other hand, with the rapid development of modern technologies and the emergence of large-scale integrated circuits, the number of electrical and electronic devices is increasing, and electronic devices are becoming more and more integrated, miniaturized and networked. Rapid development also has many negative effects, and electromagnetic interference is one of the problems. A large number of electronic devices operate in the same electromagnetic environment, the frequency band is wider and wider, the power is larger and larger, the sensitivity is also improved, and the cable network for connecting the devices is also more and more complex, so the problem of electromagnetic compatibility is more and more serious. The electromagnetic compatibility discipline has a very wide range, and the field of satellite internet of things is only in a starting stage in the aspect of electromagnetic compatibility research.

Electromagnetic Compatibility (EMC), is a science that studies that electronic devices work together without performance impact under the same Electromagnetic environment. Another definition is "the ability of equipment and systems to function properly in their electromagnetic environment and not to constitute an unacceptable electromagnetic disturbance to anything in the environment". The definition includes two aspects, firstly, the device should be able to work normally under a certain electromagnetic environment, that is, the device should have a certain electromagnetic immunity (EMS); secondly, the electromagnetic disturbance generated by the equipment cannot generate excessive influence, namely electromagnetic disturbance (EMI), on other electronic products. To improve the electromagnetic compatibility of the electronic equipment, not only the electromagnetic compatibility immunity of the equipment needs to be improved, but also the electromagnetic disturbance of the electronic equipment needs to be reduced.

Electromagnetic compatibility has become an important discipline in modern electronics and is subsequently developing more rapidly. Some countries have established mechanisms for electromagnetic compatibility inspection and management of military and civil supplies, and the electromagnetic compatibility standard has become a firm technical barrier for restricting imported products in developed countries.

In addition, practice also proves that if the electromagnetic compatibility problem is solved in the stages of product design development and production, the possibility of electromagnetic interference is taken into consideration from the design of a circuit to the selection of components, the overall anti-interference capability is improved from the inside of a system, and the improvement cost after the design and the design of the product and even the batch production is greatly reduced. Therefore, increasing the electromagnetic compatibility of the Data Collection System (DCS) load has become an irrevocable task. Some problems arising during the in-orbit communication of the satellite in the sky need to be researched and solved, and the related electromagnetic compatibility problem needs to be solved.

Disclosure of Invention

The invention aims to solve the technical problem of providing an EMC analysis model and an EMC characteristic improvement method for a communication load of a sky start constellation aiming at the defects in the prior art.

The invention provides an EMC analysis model and an EMC characteristic improvement method for a sky start constellation communication load, which comprises the following steps:

aiming at load radiation disturbance, an EMC analysis model of the load of the launch satellite is established, the EMC analysis model comprises a load cabin, a load structure cabin arranged in the load cabin and a load antenna connected to the load structure cabin, and the following parameters are set:

R₀natural noise and interference signals entering the load antenna from the outside;

c: the conductivity coefficient of a coaxial radio frequency cable between the load antenna and the load;

g: a load path gain;

R_d: the radiation coefficient of the DCS load to the satellite interference signal;

R_s: radiation coefficient of interference signals of the star body to the load antenna;

E_d: load structureThe shielding factor of the compartment is such that,

E_s: shielding coefficient of the satellite load compartment;

determining the noise bottom N of the load receiving channel under the ideal condition according to the load EMC analysis model₀Comprises the following steps: n is a radical of₀＝R₀+ C + G (for ease of calculation, the unit is in decibels, i.e., dB);

determining the interference of the noise bottom after radiation coupling back to the load antenna as follows:

N₁＝[(N₀-E_d)*R_d-E_s]*R_s+C+G；

the same principle is as follows: n is a radical of_i＝[(N_i-1-E_d)*R_d-E_s]*R_s+C+G，

Wherein: i is a natural number, N_iInterference that is radiatively coupled back to the loaded antenna the ith time.

Thus, the actual load receive channel noise floor is determined as:

preferably, the EMC characteristics are improved by reducing the coaxial radio frequency cable conduction coefficient C between the load antenna and the load, the load channel gain G, DCS load to star interference signal radiation coefficient Rd and the star to load antenna interference signal radiation coefficient Rs.

Preferably, the EMC characteristics are improved by increasing the shielding coefficient of the Ed load structure bay and the shielding coefficient Es of the star load bay.

Preferably, the conductivity of the coaxial radio frequency cable between the load antenna and the load is a fixed value.

Preferably, the radiation coefficient of DCS load to the satellite interference signal is reduced by attaching a wave-absorbing material inside the load chamber.

Preferably, the shielding factor of the load carrying structural compartment is increased by means of the addition of shielding material.

Preferably, the shielding coefficient of the star load chamber is increased by adding shielding material.

Preferably, the load connector gap and the structural gap are wrapped by using shielding materials to improve EMC characteristics.

Preferably, the EMC characteristics are improved by shielding the load supply line and the data line.

Preferably, the EMC characteristics are improved by wrapping the holes through the cable on the satellite load compartment plate with a shielding material.

Drawings

A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

fig. 1 schematically shows an example of an EMC analytical model employed in accordance with a preferred embodiment of the present invention.

Fig. 2 schematically shows a DCS load EMC test connection block diagram employed according to a preferred embodiment of the present invention.

Fig. 3 schematically shows a 240MHz spectrum (noise floor of-95 dBm) obtained from a pre-test conducted EMC characteristic improvement measure according to a preferred embodiment of the present invention.

Fig. 4 schematically shows a 240MHz spectrum (noise floor of-115 dBm) obtained from a test conducted after EMC characteristic improvement measures are implemented according to a preferred embodiment of the present invention.

It is to be noted, however, that the appended drawings illustrate rather than limit the invention. It is noted that the drawings representing structures may not be drawn to scale. Also, in the drawings, the same or similar elements are denoted by the same or similar reference numerals.

Detailed Description

In order that the present disclosure may be more clearly and readily understood, reference will now be made in detail to the present disclosure as illustrated in the accompanying drawings.

According to the design scheme and the whole satellite structure of the communication load of the satellite launch constellation, the EMC analysis model of the communication load of the satellite launch constellation is established for the first time, the calculation formula of the electromagnetic interference noise floor of the load is given, and a theoretical basis is provided for EMC analysis and EMC protection of the communication load of the satellite launch satellite DCS (Data Collection System).

Practice shows that if the electromagnetic compatibility can be taken into consideration in the load design and development process, the advantages and the defects of an anti-interference device are taken into consideration, and the reliability and the safety of the load can be greatly improved. The analysis method adopting the model is successfully applied in the process of testing and developing the EMC of the communication load of the sky start constellation, and according to a series of improvement measures provided by the analysis model, the fact proves that the method is very effective, and the sensitivity of the receiver can be improved by more than 2 dB. The model and the calculation formula also have reference significance for further improving the EMC characteristics of the same type of communication load.

DCS load EMC analysis model

Aiming at the problem of electromagnetic interference which is increasingly worsened at present, the DCS load also needs to standardize and improve relevant standards of electromagnetic compatibility, and the electromagnetic compatibility performance of products is improved.

The electromagnetic interference mainly includes the following modes:

1) radiation interference: electromagnetic interference sources couple (interfere) signals to another electrical network through a spatial form (electric field, magnetic field).

2) Conduction interference: electromagnetic interference sources couple (interfere) signals on one electrical network to another electrical network through a conductive medium. Generally defined by a voltage or a current.

3) Electrostatic discharge: the charge transfer occurs when objects with different electrostatic potentials approach or touch.

4) Electrical fast transient pulse burst: there are pulses of a specific duration (specified as 15ms) and a specific pulse period (300 ms).

5) Surge (impact): transient over-voltages/currents that exceed the normal operating voltage.

The frequency band of DCS load work is relatively high, mainly 240 MHz-400 MHz, so that radiation interference is the most main interference source of DCS load in the satellite orbit flight process.

There are three basic elements in creating electromagnetic interference or electromagnetic hazards: electromagnetic interference sources, electromagnetic energy coupling pathways, and sensitive objects. The DCS load is taken as a sensitive object, and the electromagnetic energy coupling path mainly considers radiation coupling and conduction coupling. Conductive coupling requires a complete electrical connection between the electromagnetic interference source and the sensitive object, while radiative coupling is where the interference source couples (disturbs) a signal to the sensitive object in a spatial form (electric field, magnetic field). The electromagnetic interference source may be any component on the load or the satellite that generates electromagnetic interference.

In order to ensure that the DCS load is not influenced by electromagnetic interference of other electronic equipment of a satellite platform and normal operation of other equipment while working normally, the electromagnetic interference problem occurring in DCS load development and in-orbit operation needs to be solved by switching in from three elements and analyzing the nature of interference.

Here, an EMC analysis model as shown in fig. 1 is established for load radiation disturbance according to the configuration of the whole satellite and the load of the celestial satellite, wherein the EMC analysis model comprises a load cabin, a load structure cabin arranged in the load cabin, and a load antenna connected to the load structure cabin. For the definition of parameters, wherein:

R₀natural noise and interference signals entering the load antenna from the outside; manual intervention cannot be performed;

c: the conductivity coefficient of a coaxial radio frequency cable between the load antenna and the load; a fixed value;

g: a load path gain;

R_d: the radiation coefficient of the DCS load to the satellite interference signal; the wave-absorbing material can be adhered to the interior of the load chamber;

R_s: radiation coefficient of interference signals of the star body to the load antenna;

E_d: the shielding coefficient of the load carrying structural compartment can be increased by adding shielding material.

E_s: shielding coefficient of the satellite load compartment; this factor can be increased by adding shielding material;

according to the load EMC analysis model, the noise bottom N of the load receiving channel is ideally₀Should be as shown in the following equation (in dB):

N₀＝R₀+C+G (1)

the interference of the noise floor coupled back to the load antenna by radiation is as follows:

N₁＝[(N₀-E_d)*R_d-E_s]*R_s+C+G (2)

the same principle is as follows: n is a radical of_i＝[(N_i-1-E_d)*R_d-E_s]*R_s+C+G (3)

Wherein: i is a natural number, N_iInterference that is radiatively coupled back to the loaded antenna the ith time.

Thus, the actual load receive channel noise floor is determined as:

from the above equations, it can be seen that it is desirable to minimize C, G, Rd, Rs while increasing Ed and Es. Subsequent measures for improving the EMC behavior of the load are also proposed on the basis of the evaluation model.

Application of EMC analysis model in EMC test

In an EMC laboratory, an EMC test is performed on a DCS load according to a test connection block diagram shown in FIG. 2. As shown in fig. 2, a 401M antenna and 240/320 antenna are configured for a satellite with DCS payload, the payload ground detector communicates with the 401M antenna of the satellite through one attenuator via one 401M antenna, and the payload ground detector communicates with the 240/320 antenna of the satellite through another attenuator via one 240/320 antenna.

The test mainly verifies the load receiving sensitivity in the whole satellite wireless state and judges whether the platform influences the load receiving sensitivity.

In order to improve the EMC characteristics of the load, the load path gain G can be reduced according to the formula, for which G is reduced by 10dB, and the results of the spectral processing of the 240MHz band before and after the reduction are shown in fig. 3 and 4. It can be seen that the noise floor is reduced by 20 dBm. In addition, the test report of data reception shows that the sensitivity of the receiver is improved by at least more than 2 dB.

With the development of the satellite internet of things, the EMC problem of the DCS load is increasingly prominent. Due to the characteristics of low signal-to-noise ratio and large Doppler frequency shift of the Internet of things satellite communication, signal acquisition and demodulation are relatively difficult, and the problem of solving the EMC of the load is greatly helped to improve the problem. In addition, practice also proves that if the electromagnetic compatibility problem is solved in the load design and development stage, the possibility of electromagnetic interference is considered from the design of a circuit to the selection of components, the overall anti-interference capability is improved from the inside of a system, and the improvement cost after the load is greatly reduced.

According to equation (1), the channel gain G is reduced by 10dB, and the initial noise will also be reduced by 10 dB. While the noise floor is ultimately reduced by 20 dBm. The radiation disturbance in the loop is close to an order of magnitude with the initial noise, the channel gain is reduced, and the influence of the radiation disturbance on the noise bottom is also reduced.

According to the model, increasing Ed and Es can also improve the EMC characteristic of the load, and the following measures can be taken subsequently:

1) wrapping the load connector gap and the structural gap by using shielding materials;

2) shielding the load power supply line and the data line;

3) and covering the holes for penetrating the cables on the cabin plate of the satellite load cabin by using shielding materials.

By carefully analyzing the electromagnetic environment, electromagnetic compatibility and electromagnetic interference principles of the load, researching the reasons of electromagnetic interference generation in the working frequency band of the load and reasonably applying the electromagnetic compatibility method, the electromagnetic interference can be inhibited. Therefore, the DCS load can work normally and reliably in a complex space electromagnetic environment, the function and performance of the electromagnetic compatibility of the DCS load meet the design requirements, and the accuracy of data communication is greatly improved, so that the EMC analysis model and the calculation formula have important practical significance. The model can be continuously improved in subsequent load development and use, so that the model is more suitable for practical application.

It should be noted that the terms "first", "second", "third", and the like in the description are used for distinguishing various components, elements, steps, and the like in the description, and are not used for indicating a logical relationship or a sequential relationship between the various components, elements, steps, and the like, unless otherwise specified.

It is to be understood that while the present invention has been described in conjunction with the preferred embodiments thereof, it is not intended to limit the invention to those embodiments. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.