On-orbit channel self-calibration method of communication satellite

Abstract

The invention discloses an in-orbit channel self-calibration method of a communication satellite. The method comprises the following steps: step 1, carrying out channel balancing on the ground by using a single-channel point-by-point enabling method, so that amplitude-phase errors among channels of a full-flexible communication load meet system requirements; 2, on the ground, through an on-orbit channel calibration system, a wide-beam calibration antenna and a load array radio frequency channel form a closed loop, and establishment of an amplitude-phase calibration initial association table is completed; and step 3, on the satellite, acquiring amplitude-phase signals among the channels through a calibration processor, a radio frequency transceiving channel and a calibration antenna, and performing error comparison on the acquired amplitude-phase signals and the initial association table to realize on-orbit channel self-calibration. According to the invention, the highly integrated satellite antenna feed source array can realize simultaneous and efficient self-calibration of multiple channels in an in-orbit operation state, the calibration real-time performance and the engineering feasibility are improved, and the calibration precision is improved at the same time.

Description

Technical Field

[0001] This invention belongs to the field of satellite payload channel calibration technology, and relates to an on-orbit channel self-calibration method for communication satellites, particularly for fully flexible communication payloads, involving an active multi-beam system of onboard digital beamforming network (DBF) and digital transparent processor (DTP). Background Technology With increasing uncertainty in the international satellite market, fully flexible communication satellites are gaining more and more favor. Once in orbit, fully flexible satellites possess flexible adjustment and control capabilities in areas such as beam coverage, spectrum management, power allocation, interconnection, and protocol systems, making them "game changers in the market."

[0002] The fully flexible communication satellite, through the collaborative work of multi-beam antenna technology, DTP with DBF function, arrayed frequency converters, and traveling wave tube amplifiers, achieves flexible payload requirements in terms of beam coverage, pointing, frequency, and power. Amplitude and phase consistency of each RF channel is the foundation for achieving all this high efficiency, reliability, and flexibility. However, the amplifiers, frequency converters, and other analog devices and their associated active circuits within the array channels inevitably exhibit amplitude and phase differences. These differences, coupled with external factors such as temperature, humidity, device noise, and aging, inevitably exacerbate channel mismatch issues between arrays. Channel mismatch affects array system performance, leading to increased sidelobe levels, adversely impacting beamforming, shallower interference nulls, decreased array gain, and ultimately, severely degraded output performance—a series of array signal processing problems. Therefore, on-orbit channel calibration is imperative.

[0003] The purpose of on-orbit channel calibration is: (1) to compensate for the influence of channel amplitude and phase differences caused by temperature distribution and changes on the beam pattern of the on-orbit antenna array and RF channel; (2) to compensate for the influence of channel amplitude and phase differences on the beam pattern after the performance degradation of the RF channel in the later stage of the on-orbit life; (3) as part of antenna telemetry, to check the health of the channel.

[0004] Currently, existing satellite on-orbit channel calibration technologies mainly revolve around antenna performance correction, payload parameter calibration, and channel amplitude and phase consistency compensation, forming several mainstream implementation schemes: For low-Earth orbit (LEO) satellite uplink phased array antennas, a ground calibration station transmits a single-carrier calibration signal and a reference signal, the onboard equipment transmits signal-to-noise ratio (SNR) data, and the ground system iteratively corrects beam pointing deviation through differential, interpolation, and normalization processing; For high-throughput satellites, uplink and downlink dual test links are constructed, and the satellite input / output signal power is calculated to complete payload calibration by combining the spectrum analyzer's filtering and noise reduction function with power meter readings and loss correction values; For channel amplitude and phase consistency, one approach is to generate an amplitude and phase compensation matrix in channel ergonomic mode using onboard internal calibration components, and achieve phased array antenna self-calibration by combining time-domain averaging and FFT point frequency calculation; another approach is to set up a calibration source in the communication processor and use the transmit / receive time slot switching to compensate for RF channel amplitude and phase deviation; For high-Earth orbit (HEO) satellites, standardized test commands are generated by the on-orbit test center station and remote station to simultaneously conduct transponder performance tests, and the data is summarized to generate a report to complete automated calibration.

[0005] However, existing calibration methods still have shortcomings when targeting highly integrated active multi-beam antennas and fully flexible communication payload systems: First, the calibration scope is limited to a single component or local channel, failing to perform overall system calibration by treating the active multi-beam antenna and payload array RF channels as a closed loop, thus failing to fundamentally solve the channel mismatch problem between arrays; calibration efficiency is low and adaptability is insufficient, with some methods using a single-channel traversal mode and others relying on ground stations or multi-station collaboration, making it difficult to meet the simultaneous multi-channel calibration requirements of highly integrated antenna feed arrays; Second, temperature adaptability is poor, failing to fully consider the differences and dynamic changes in on-orbit temperature distribution, relying only on room temperature parameter estimation or fixed compensation values, which cannot compensate for channel amplitude and phase deviations caused by temperature; Third, long-term stability is insufficient, with existing methods mostly targeting the initial or short-term calibration of satellites in orbit, failing to establish a continuous compensation mechanism for device performance degradation in the middle and later stages of on-orbit life, and the accumulation of amplitude and phase deviations will affect calibration accuracy; Fourth, there is a lack of channel health status monitoring function, with existing methods only focusing on amplitude and phase deviation correction, failing to use calibration data to feedback the working status of key components, failing to provide early warning of potential faults, and reducing the reliability and maintenance convenience of satellite operation in orbit. Summary of the Invention

[0006] The purpose of this invention is to provide an on-orbit channel self-calibration method for communication satellites, so as to solve the technical problems of existing calibration methods, such as the calibration range being limited to local areas, insufficient adaptability of multi-channel parallel calibration, and lack of temperature dynamic error compensation.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A method for on-orbit channel self-calibration of a communication satellite includes the following steps: Step 1: Use the single-channel point-by-point enable method to perform channel balancing on the ground, so that the amplitude and phase errors between each channel of the fully flexible communication payload meet the system requirements; Step 2: On the ground, through the on-orbit channel calibration system, the wide-beam calibration antenna and the payload array RF channel are connected to form a closed loop to complete the establishment of the initial correlation table for amplitude and phase calibration. Step 3: Onboard, the amplitude and phase signals between channels are acquired through the calibration processor, RF transceiver channel, and calibration antenna. The acquired amplitude and phase signals are then compared with the initial correlation table to achieve on-orbit channel self-calibration.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves on-orbit self-calibration of communication satellites. It employs an external calibration method and designs a multi-channel synchronous calibration mechanism for highly integrated antenna feed arrays, coupled with an on-orbit self-calibration system consisting of a calibration processor, RF transceiver channels, and calibration antennas. This enables highly integrated satellite antenna feed arrays to achieve simultaneous and efficient multi-channel self-calibration while in orbit, improving the real-time performance and engineering feasibility of calibration.

[0009] 2. An amplitude and phase error calculation and compensation mechanism is introduced. By periodically transmitting RF calibration signals through the calibration antenna, and then down-converting and processing the data via the DTP channel, the mechanism compensates for the impact of amplitude and phase differences in the on-orbit antenna array and RF channels caused by temperature distribution and variations on the beam pattern. This effectively maintains the shape, pointing accuracy, and sidelobe level performance of the beam pattern, ensuring stable on-orbit communication quality.

[0010] 3. The on-orbit self-calibration process will be integrated throughout the entire satellite lifecycle. By monitoring the amplitude and phase characteristics of the radio frequency channel through the calibration system and using a closed-loop mechanism of "signal transmission-error calculation-compensation," calibration accuracy can be effectively improved. In the mid-to-late stages of the satellite's on-orbit life, amplitude and phase deviations caused by radio frequency channel performance degradation can be detected, and compensation can be used to maintain the beam pattern design specifications and extend the satellite's effective service life.

[0011] 4. The calibration function is integrated into the antenna telemetry system, and the amplitude and phase parameters of each channel are collected synchronously through the self-calibration process, eliminating the need for additional detection modules. This allows the calibration process to be used for channel health monitoring simultaneously, identifying performance anomalies in individual or group of channels at an early stage, providing critical telemetry data support for predictive maintenance of the satellite platform, and reducing operation and maintenance costs. Attached Figure Description

[0012] Figure 1 This is a flowchart of the on-orbit self-calibration process for communication satellites according to the present invention.

[0013] Figure 2 This is a schematic diagram of the calibration principle for the receiving channel.

[0014] Figure 3 This is a schematic diagram of the calibration principle for the transmission channel. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings.

[0016] like Figure 1 As shown, the on-orbit channel self-calibration method for communication satellites provided by this invention includes the following steps: Step 1: Use the single-channel point-by-point enable method to perform channel balancing on the ground, so that the amplitude and phase errors between each channel of the fully flexible communication payload meet the system requirements; Specifically, the single-channel point-by-point enable method is applicable to array antennas where each channel can be opened independently. The specific operation is as follows: control the movement of the scanning frame mechanism to align the test probe with each feed of the array antenna under test one by one; control each element under test (i.e., each feed element in the feed array of the array antenna under test) to maintain an independent transmit / receive state, while the remaining elements are in a matched state; use a vector network analyzer to acquire amplitude and phase data of the element under test to obtain the amplitude and phase data of all elements, and perform channel balancing processing.

[0017] Specifically, the fully flexible communication payload is a commonly used system in this field. In this embodiment, the system includes a DBF and DTP, an active multi-beam antenna, an array amplifier, and an array converter. The analog devices such as the array amplifier and array converter, and the active circuits they form, inevitably exhibit amplitude and phase differences, leading to channel mismatch issues between arrays. Channel mismatch affects the performance of the array system, thus requiring on-orbit channel calibration. Because the feed array of the antenna under test is highly integrated and very compact, the system employs an external calibration method, performing calibration on multiple channels simultaneously.

[0018] Step 2: On the ground, the wide-beam calibration antenna and the payload array RF channel are connected to form a closed loop through the on-orbit channel calibration system to complete the establishment of the initial correlation table for amplitude and phase calibration.

[0019] Specifically, a wide-beam calibration antenna is set up near the array surface to cover the array surface. The calibration antenna and the RF channel of the payload array form a closed loop to complete the establishment of the initial correlation table for amplitude and phase calibration.

[0020] Specifically, the on-orbit channel calibration system is a commonly used system in this field. In this embodiment, the system includes at least a calibration processor, an RF transceiver channel, and a calibration antenna.

[0021] Step 3: Onboard, the amplitude and phase signals between channels are acquired through the calibration processor, RF transceiver channel, and calibration antenna. The acquired amplitude and phase signals are then compared with the initial correlation table to achieve on-orbit channel self-calibration.

[0022] Specifically, during on-orbit channel self-calibration, the mutual coupling between the calibration antenna and all elements in the array needs to be controlled within a reasonable range (based on experience and conventional settings) to ensure that the dynamic range during measurement is as small as possible, thereby ensuring that the receiver has sufficient amplitude and phase accuracy under calibration conditions.

[0023] In a preferred embodiment of the present invention, on-orbit channel self-calibration includes receive channel calibration and transmit channel calibration, wherein: like Figure 2 As shown, the receiving channel calibration process is as follows: 1) The calibration processor sends an intermediate frequency calibration signal, which is then up-converted to obtain an radio frequency calibration signal. The radio frequency calibration signal is then sent to the antenna receiving array through the calibration antenna. 2) After the RF calibration signal is sampled by multiple ADCs in the downconversion and DTP receiving channels, the beam weights and subband switching relationships are controlled. 3) Use the calibration fiber interface located in the subband switching processor (DTP) to send the baseband signal received by the array channel back to the calibration processor. 4) The calibration processor calculates the amplitude and phase errors of each receiving channel relative to the initial correlation table, and compensates for these amplitude and phase errors in the receiving digital beamforming network to complete the calibration of the receiving channels.

[0024] like Figure 3 As shown, the calibration process for the transmission channel is as follows: 1) The calibration processor simultaneously generates baseband signals for all channels, each signal using a different Walsh code, and all baseband signals are simultaneously sent to the dedicated calibration fiber optic interface of the sub-band switching processor. 2) The DTP internally controls the subband switching relationship and beam weights to simultaneously exchange the received calibration signal to each transmit channel, with each transmit channel corresponding to an independent Walsh code; 3) The calibration antenna simultaneously receives the sum of calibration signals from all channels, and the sum of the signals is sent back to the ADC of the calibration processor; 4) The calibration processor calculates the amplitude and phase errors of each transmission channel relative to the initial correlation table, compensates for these amplitude and phase errors in the transmission digital beamforming network, and completes the calibration of the transmission channels.

[0025] In the above calibration of the receiving channel and the transmitting channel, the calibration signal adopts a broadband design with a channel bandwidth of 300MHz~3GHz. During the calibration process, the calibration of multiple frequency points is completed by simultaneously acquiring and assigning values ​​to multiple frequency points.

[0026] Specifically, the following conditions must be met when the final on-orbit channel self-calibration is completed: amplitude error between channels ≤ ±0.5dB, phase error ≤ ±5°.

Claims

1. A method for on-orbit channel self-calibration of a communication satellite, characterized in that, Includes the following steps: Step 1: Use the single-channel point-by-point enable method to perform channel balancing on the ground, so that the amplitude and phase errors between each channel of the fully flexible communication payload meet the system requirements; Step 2: On the ground, through the on-orbit channel calibration system, the wide-beam calibration antenna and the payload array RF channel are connected to form a closed loop to complete the establishment of the initial correlation table for amplitude and phase calibration. Step 3: Onboard, the amplitude and phase signals between channels are acquired through the calibration processor, RF transceiver channel, and calibration antenna. The acquired amplitude and phase signals are then compared with the initial correlation table to achieve on-orbit channel self-calibration.

2. The method according to claim 1, characterized in that: In step 1, the specific operation of the single-channel point-by-point enabling method is as follows: The scanning frame mechanism is controlled to align the test probes one by one with the feeds of the antenna under test; each element under test (i.e., each feed element in the feed array of the antenna under test) is controlled to maintain an independent transmit / receive state, while the remaining elements are in a matched state; the amplitude and phase data of all elements are obtained by acquiring amplitude and phase data of the elements under test using a vector network analyzer, and channel balancing is performed.

3. The method according to claim 1, characterized in that: In step 1, the fully flexible communication payload is an active multi-beam system including DBF and DTP, active multi-beam antenna, array amplifier, and array frequency converter. This system adopts an external calibration method, and multiple channels are calibrated simultaneously.

4. The method according to claim 1, characterized in that: In step 2, a wide-beam calibration antenna is set up near the array surface to cover the array surface. The calibration antenna and the RF channel of the payload array form a closed loop to complete the establishment of the initial correlation table for amplitude and phase calibration.

5. The method according to claim 1, characterized in that: In step 2, the on-orbit channel calibration system includes a calibration processor, an RF transceiver channel, and a calibration antenna.

6. The method according to claim 1, characterized in that: In step 3, the on-orbit channel self-calibration includes receiving channel calibration and transmitting channel calibration.

7. The method according to claim 6, characterized in that: The receiving channel calibration process is as follows: 1) The calibration processor sends an intermediate frequency calibration signal, which is then up-converted to obtain an radio frequency calibration signal. The radio frequency calibration signal is then sent to the antenna receiving array through the calibration antenna. 2) After the RF calibration signal is sampled by multiple ADCs in the downconversion and DTP receiving channels, the beam weights and subband switching relationships are controlled. 3) Use the calibration fiber interface located in the subband switching processor (DTP) to send the baseband signal received by the array channel back to the calibration processor. 4) The calibration processor calculates the amplitude and phase errors of each receiving channel relative to the initial correlation table, and compensates for these amplitude and phase errors in the receiving digital beamforming network to complete the calibration of the receiving channels.

8. The method according to claim 6, characterized in that: The calibration process for the transmission channel is as follows: 1) The calibration processor simultaneously generates baseband signals for all channels, each signal using a different Walsh code, and all baseband signals are simultaneously sent to the dedicated calibration fiber optic interface of the sub-band switching processor. 2) The DTP internally controls the subband switching relationship and beam weights to simultaneously exchange the received calibration signal to each transmit channel, with each transmit channel corresponding to an independent Walsh code; 3) The calibration antenna simultaneously receives the sum of calibration signals from all channels, and the sum of the signals is sent back to the ADC of the calibration processor; 4) The calibration processor calculates the amplitude and phase errors of each transmission channel relative to the initial correlation table, compensates for these amplitude and phase errors in the transmission digital beamforming network, and completes the calibration of the transmission channels.

9. The method according to claim 1, characterized in that: In step 3, the calibration signal adopts a broadband design with a channel bandwidth of 300MHz~3GHz. During the calibration process, the calibration work of multiple frequency points is completed by simultaneously acquiring and assigning values ​​to multiple frequency points.

10. The method according to claim 1, characterized in that: When the on-orbit channel self-calibration ends, the following conditions must be met: amplitude error between channels ≤ ±0.5dB, phase error ≤ ±5°.

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