A method for on-orbit calibration of a CDM-based low-orbit communication satellite downlink phased array antenna

Abstract

The application relates to a kind of on-orbit calibration methods of low-orbit communication satellite downlink phased array antenna based on CDM, belonging to the field of satellite testing technology.The method takes the pointing measurement and calibration of low-orbit communication satellite downlink phased array antenna as input, and realizes the measurement and calibration of the beam pointing of the downlink phased array antenna through the test and data processing of multiple beams EIRP of the downlink phased array antenna.The method has the functions of calibration signal generation, beam EIRP test, beam three-dimensional directional diagram reconstruction, pointing deviation measurement and beam pointing adjustment.Simulation experiments show that the calibration method designed by the application can effectively reduce the beam pointing deviation of low-orbit communication satellite downlink phased array antenna.

Description

TECHNICAL FIELD

[0001] The application relates to an on-orbit calibration method for a CDM-based low-orbit communication satellite downlink phased array antenna. BACKGROUND

[0002] Compared with high-orbit satellites, a low-orbit satellite constellation has obvious advantages in terms of launch cost and global coverage, and has characteristics such as strong invulnerability, low transmission delay, low link attenuation and high communication rate, so that a low-orbit satellite network system characterized by a low-orbit mega constellation is booming in the global range.

[0003] With the low-orbit satellite constellation entering a large-scale deployment stage, satellites need to be mass-produced and launched, and a ground test system cannot guarantee that test contents cover all satellites. In addition, due to the complex space environment of low-orbit satellites, the satellites are affected by factors such as atmospheric environment, particle radiation and electromagnetic radiation environment, and geomagnetic field environment, which may cause the on-board antenna to malfunction. In order to guarantee the on-orbit service quality of the satellite, on-orbit supplementary testing and calibration of the antenna pointing of the satellite antenna are needed to improve the pointing accuracy of the beam and meet the use requirements of the system. If the uplink and downlink phased array antennas on the satellite are independent single machines, the uplink and downlink calibration tests need to be performed respectively.

[0004] Calibration tests can be divided into downlink calibration and uplink calibration. Downlink beam calibration is usually performed by a gateway station or a satellite transmitting calibration signals, and a beam calibration receiving station is set on the ground. The receiving station discriminates the energy of different beam calibration signals to obtain the antenna pointing error. Uplink beam calibration is performed by a ground beam calibration station transmitting calibration signals, and the satellite or the gateway station estimates the energy and compares the field strength to obtain the antenna pointing error. The Thuraya system adopts an uplink calibration scheme. Both calibration schemes are used in the Aces satellite system. SUMMARY

[0005] The application is aimed at the pointing measurement and calibration of a low-orbit communication satellite downlink phased array antenna, and realizes the measurement and calibration of the beam pointing of the downlink phased array antenna through the testing and data processing of multiple beams EIRP of the downlink phased array antenna. Simulation experiments show that the calibration method designed in the application can effectively reduce the beam pointing deviation of the low-orbit communication satellite downlink phased array antenna.

[0006] The calculation scheme adopted in the application is as follows:

[0007] An on-orbit calibration method for a CDM (code division multiple access)-based low-orbit communication satellite downlink phased array antenna, comprising the following steps:

[0008] Step 1: The satellite transmits equal-power calibration signals in multiple beams of the downlink phased array antenna, and transmits a reference signal through an omnidirectional antenna;

[0009] Step 2: In the test window of the low-orbit satellite, the ground calibration station receives the calibration signals and the reference signal, and obtains the measurement result of the EIRP (Equivalent Isotropically Radiated Power) value of the satellite through processing;

[0010] Step 3: The ground data processing system receives and stores the measurement data of multiple calibration stations and multiple test window periods, classifies and processes the data, and obtains the three-dimensional pattern data of the multiple beams;

[0011] Step 4: The ground data processing system performs normalization processing on the three-dimensional pattern data of the multiple beams to obtain the measurement value of the pointing of the satellite downlink phased array antenna, and compares and analyzes it with the design value to form an analysis result;

[0012] Step 5: The ground data processing system determines the beam offset according to the analysis result, formulates an avoidance, adjustment or processing strategy in combination with information including the orbit, attitude of the satellite and communication quality of the terminal user, and remotely controls the on-satellite execution through the TT&C signal;

[0013] Step 6: In the test window period of the low-orbit satellite, the ground calibration station continues to measure the beam pointing of the adjusted satellite downlink phased array antenna, and corrects the pointing deviation through iteration until the beam pointing of the satellite downlink phased array antenna meets the system requirements.

[0014] Further: The specific process of Step 1 is as follows:

[0015] Step 101: The satellite transmits equal-power calibration signals in multiple beams of the downlink phased array antenna, and the calibration signal is a narrowband signal of orthogonal code division multiple access, containing satellite number, position, attitude, antenna installation matrix and time information;

[0016] Step 102: The satellite transmits a reference signal through an omnidirectional antenna, and the reference signal is a single-carrier signal.

[0017] Further: The specific process of Step 2 is as follows:

[0018] Step 201: In the test window of the low-orbit satellite, the ground calibration station device receives the calibration signal and the reference signal, obtains the power values received from different beams of the satellite downlink phased array antenna and the power value of the reference signal, and obtains the EIRP values of different beams of the satellite downlink phased array antenna through differential calculation;

[0019] Step 202: The ground calibration station device parses the number, position, attitude, antenna installation matrix and time information of the satellite in the calibration signal;

[0020] Step 203: The ground calibration station device calculates the azimuth and elevation angles of the ground calibration station in the satellite antenna coordinate system according to the geographical position, satellite position, attitude and antenna installation matrix of the calibration station and other information;

[0021] Step 204: The ground calibration station device calculates the time stamp corresponding to each sampling point by interpolation according to the time information of the satellite;

[0022] Step 205: The ground calibration station device timestamps the satellite number, the number of different beams of the satellite downlink phased array antenna, the EIRP value, the azimuth and elevation angles of the ground calibration station in the satellite antenna coordinate system, and transmits them to the ground data processing system.

[0023] Further: the specific process of step 3 is as follows:

[0024] Step 301: The ground data processing system receives and stores the measurement data of multiple calibration stations and multiple test window periods;

[0025] Step 302: The ground data processing system classifies the measurement data according to the satellite number and beam number;

[0026] Step 303: The ground data processing system processes the classified data to obtain the three-dimensional directional diagram data of multiple beams.

[0027] Compared with the background art, the present application has the following advantages:

[0028] 1. The calibration signals transmitted by the satellite in multiple beams of the downlink phased array antenna adopt the CDM multiple access mode, which can eliminate the influence of the tracking accuracy of the calibration station antenna, the in-band fluctuation and time-varying characteristics of the transmission channel gain on the measurement accuracy.

[0029] 2. The calibration signals transmitted by the satellite in multiple beams of the downlink phased array antenna contain satellite number, position, attitude, antenna installation matrix and time information, which is easy to realize coordinate system conversion and satellite-ground synchronization, and is suitable for the high dynamic characteristics of the satellite.

[0030] 3. The calibration signal will be affected by the space environment such as rain and atmosphere during transmission. In order to reduce the influence of the space environment on the measurement data, the signal of the omnidirectional antenna is used as a reference signal to calibrate the measurement data. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the framework flowchart of the method designed by the present application;

[0032] Figure 2 is a schematic diagram of the system composition of the present application. DETAILED DESCRIPTION

[0033] The application will be described in detail below with reference to the drawings.

[0034] Referring to Figure 1 and Figure 2 A method for in-orbit calibration of a CDM-based low-orbit communication satellite downlink phased array antenna, comprising the following steps:

[0035] Step 1: Figure 2 The satellite in the step 1 transmits equal-power calibration signals in multiple beams of the downlink phased array antenna, and transmits a reference signal through an omnidirectional antenna;

[0036] The step 1 comprises the following processes:

[0037] Step 101: The satellite transmits equal-power calibration signals in multiple beams of the downlink phased array antenna, and the calibration signals are narrowband signals of orthogonal code division multiple access, containing information such as satellite number, position, attitude, antenna installation matrix and time;

[0038] Step 102: In order to reduce the influence of the space environment on the measurement data, the satellite transmits a reference signal through an omnidirectional antenna, and the reference signal is a single-carrier signal.

[0039] Step 2: In a test window of the low-orbit satellite, Figure 2 The ground calibration station in the step 2 receives the calibration signals and the reference signal, and processes to obtain the measurement result of the satellite EIRP value;

[0040] The step 2 comprises the following processes:

[0041] Step 201: In the test window of the low-orbit satellite, the ground calibration station device receives the calibration signals and the reference signal, obtains the power values of the reference signal and the calibration signals received from different beams of the satellite downlink phased array antenna, and calculates the EIRP values of the different beams of the satellite downlink phased array antenna through difference calculation;

[0042] Step 202: The ground calibration station device parses the information such as the number, position, attitude, antenna installation matrix and time of the satellite in the calibration signals;

[0043] Step 203: The ground calibration station device calculates the azimuth and elevation angles of the ground calibration station in the satellite antenna coordinate system according to the information such as the geographical position of the calibration station, the satellite position, the attitude and the antenna installation matrix;

[0044] Step 204: The ground calibration station device calculates the time stamp corresponding to each sampling point through interpolation according to the time information of the satellite;

[0045] Step 205: The ground calibration station device timestamps the number of the satellite, the number of the different beams of the satellite downlink phased array antenna, the EIRP value, the azimuth and elevation angles of the ground calibration station in the satellite antenna coordinate system, and transmits them to Figure 2The ground data processing system in the method.

[0046] Step 3: The ground data processing system receives and stores the measurement data of the multiple calibration stations and the multiple test window periods, classifies and processes the data, and obtains the stereographic pattern data of the multiple beams.

[0047] In the method, step 3 comprises the following processes:

[0048] Step 301: The ground data processing system receives and stores the measurement data of the multiple calibration stations and the multiple test window periods.

[0049] Step 302: The ground data processing system classifies the measurement data according to the satellite number and the beam number.

[0050] Step 303: The ground data processing system processes the classified data, and obtains the stereographic pattern data of the multiple beams.

[0051] Step 4: The ground data processing system performs normalization processing on the stereographic pattern data of the multiple beams, obtains the measurement value of the pointing of the satellite downlink phased array antenna, compares the measurement value with a design value, and forms an analysis result.

[0052] Step 5: Figure 2 In the method, the ground data processing system determines the beam deviation condition according to the analysis result, formulates an avoidance, adjustment or processing strategy in combination with the orbit, attitude and terminal user communication quality of the satellite, and remotely controls the satellite on the ground through a measurement and control signal to execute the adjustment.

[0053] Step 6: In the test window period of the low-orbit satellite, the ground calibration station continues to measure the beam pointing of the adjusted satellite downlink phased array antenna, corrects the pointing deviation through an iterative manner, and stops until the beam pointing of the satellite downlink phased array antenna meets the system requirement.

Claims

1. A method for in-orbit calibration of a CDM-based low earth orbit communication satellite downlink phased array antenna, characterized in that, The method comprises the following steps: Step 1: the satellite transmits equal-power calibration signals in multiple beams of a downlink phased array antenna, and transmits a reference signal through an omnidirectional antenna; Step 2: in a test window of the low-orbit satellite, a ground calibration station receives the calibration signals and the reference signal, and obtains a measurement result of a satellite EIRP value through processing; Step 3: a ground data processing system receives and stores measurement data of multiple calibration stations and multiple test window periods, classifies and processes the data, and obtains stereographic pattern data of multiple beams; Step 4: the ground data processing system performs normalization processing on the stereographic pattern data of multiple beams, obtains a measurement value of a pointing direction of the satellite downlink phased array antenna, compares the measurement value with a design value, and forms an analysis result; Step 5: the ground data processing system determines a beam deviation condition according to the analysis result, formulates an avoidance, adjustment or processing strategy in combination with information including an orbit, an attitude of the satellite and a terminal user communication quality, and remotely controls the satellite through a measurement and control signal to perform the adjustment; Step 6: in the test window of the low-orbit satellite, the ground calibration station continues to measure a pointing direction of the adjusted satellite downlink phased array antenna, and iteratively corrects a pointing deviation until the pointing direction of the satellite downlink phased array antenna meets a system requirement. The specific process of Step 1 is as follows: Step 101: the satellite transmits equal-power calibration signals in multiple beams of a downlink phased array antenna, and the calibration signals are narrow-band signals of an orthogonal code division multiple access, and contain satellite number, position, attitude, antenna installation matrix and time information; Step 102: the satellite transmits a reference signal through an omnidirectional antenna, and the reference signal is a single-carrier signal.

2. The on-orbit calibration method for a CDM-based low-orbit communication satellite downlink phased array antenna according to claim 1, characterized in that: The specific process of Step 2 is as follows: Step 201: in a test window of the low-orbit satellite, a ground calibration station device receives the calibration signals and the reference signal, obtains power values of different beams of the satellite downlink phased array antenna and a power value of the reference signal, and obtains EIRP values of the different beams of the satellite downlink phased array antenna through differential calculation; Step 202: the ground calibration station device analyzes the satellite number, position, attitude, antenna installation matrix and time information in the calibration signals; Step 203: the ground calibration station device calculates an azimuth angle and a pitch angle of the ground calibration station in a satellite antenna coordinate system according to the geographical position of the calibration station, the satellite position, the attitude and the antenna installation matrix; Step 204: the ground calibration station device calculates a time stamp corresponding to each sampling point through interpolation calculation according to the time information of the satellite; Step 205: the ground calibration station device timestamps the satellite number, the satellite downlink phased array antenna beam number, the EIRP value, the azimuth angle and the pitch angle of the ground calibration station in the satellite antenna coordinate system, and transmits the timestamped data to a ground data processing system.

3. The on-orbit calibration method for a CDM-based low-orbit communication satellite downlink phased array antenna according to claim 1, characterized in that: The specific process of Step 3 is as follows: Step 301: the ground data processing system receives and stores measurement data of multiple calibration stations and multiple test window periods; Step 302: the ground data processing system classifies the measurement data according to the satellite number and the beam number; Step 303: the ground data processing system processes the classified data, and obtains stereographic pattern data of multiple beams.

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