Satellite communication system with multi-mode capability and communication method

Abstract

The invention provides a satellite communication system with multi-mode capability and a communication method, and belongs to the technical field of satellite communication. A signal processing module of the system comprises a load control unit and a baseband processing unit, the load control unit is responsible for beam correlation calculation, transmission rate control, antenna channel power-on and power-off control and the like, the baseband processing unit is used for processing uplink and downlink signals, and the downlink supports multiple modes. The frequency conversion processing module is provided with an upper frequency conversion channel and a lower frequency conversion channel which respectively process transmitted and received signals. And the wide-beam receiving antenna is responsible for receiving uplink data. The phased array transmitting antenna is responsible for transmitting downlink data, is high in gain and fast in pointing adjustment, and supports multiple modes. According to the communication method, satellite transmitting and receiving are started by default, and transmitting serves as a beacon to assist a user in capturing. According to the invention, the working modes can be flexibly switched, the telemetering downloading capability and the information broadcasting efficiency are improved, and diversified communication requirements are met.

Description

Technical Field

[0001] The present invention belongs to the field of satellite communication technology, and in particular relates to a satellite communication system and a communication method with multi-mode capabilities. Background Art

[0002] In traditional satellite communication systems, satellite tracking and control (TT&C) has long maintained a relatively fixed operating model: the satellite tracking and control system is powered on by default in the receiving module, its core task being to receive various commands from the ground; the transmitting module is powered on according to the mission plan; and the transceiver module generally uses wide-beam antennas. This architecture played an important role during a specific stage of technological development. However, with the diversification and complexity of communication needs, its single-function nature has become increasingly problematic, exposing significant deficiencies in several key aspects. Regarding telemetry downlink capabilities, the inherent performance of wide-beam antennas significantly limits signal transmission gain and directivity, resulting in low telemetry data downlink rates. Furthermore, in complex electromagnetic environments, the system suffers from weak interference immunity, making it prone to data loss or transmission errors. Regarding information broadcasting, the traditional model has significant limitations in flexibility and targeting, making it difficult to meet the diverse needs of key and general users. Key users typically prioritize real-time information, security, and transmission speed, while general users prioritize information coverage and ease of access. Summary of the Invention

[0003] The present invention aims to provide a satellite communication system and method with multimode communication capabilities, overcoming the shortcomings of traditional satellite systems in telemetry downlink and information broadcasting, thereby enabling more efficient, flexible, and targeted satellite communications. Through innovative hardware architecture and process design, this system enables flexible switching and optimized configuration between measurement and control functions and information broadcasting, aiming to fundamentally enhance the overall performance and adaptability of satellite communications and meet the growing demand for diversified communications.

[0004] The present invention is achieved in that: A satellite communication system with multi-mode capabilities, comprising a signal processing module, a frequency conversion processing module, a wide beam receiving antenna and a phased array transmitting antenna; The signal processing module includes a payload control unit and a baseband processing unit; the payload control unit is responsible for receiving the measurement and control instructions from the ground and completing the beam coverage and beam pointing calculation according to the ephemeris and star posture data broadcast by the satellite platform and the user position reported by the baseband processing unit, controlling the downlink transmission rate of the baseband processing unit and controlling the working mode and beam pointing of the phased array transmitting antenna; the payload control unit completes the channel switch of the phased array transmitting antenna according to the coverage range or the measurement and control link margin; the payload control unit performs power or beam adjustment through the phased array transmitting antenna while meeting the existing communication needs; the baseband processing unit The element is used to complete uplink signal processing and downlink signal processing; the uplink signal supports high, medium and low carrier signal processing, which respectively complete the ground station's measurement and control command parsing, user network entry information processing and user network exit information processing; among them, the low-frequency carrier signal adopts spread spectrum processing, and different network users complete network exit information reporting through different spread spectrum codes to avoid information conflicts; the measurement and control commands carried by the high-frequency carrier signal control the opening and closing of the medium and low carrier signal processing functions; the downlink signal processing supports flexible switching of multiple modes through the measurement and control commands, including beacon mode, telemetry data transmission mode and information broadcast mode; The frequency conversion processing module includes an up-conversion channel and a down-conversion channel; the up-conversion channel is used to complete the up-conversion processing of the signal transmitted by the signal processing module and send it to the phased array transmitting antenna; the down-conversion channel receives the signal through the wide beam receiving antenna, completes the amplification and down-conversion, and then sends it to the baseband processing unit; The wide beam receiving antenna is an omnidirectional antenna that receives wireless signals and sends them to the down-conversion channel of the frequency conversion processing module; The phased array transmitting antenna adopts a phased array antenna form and is composed of multiple independent channels; the phased array transmitting antenna receives the signal of the frequency conversion channel of the frequency conversion processing module and outputs it wirelessly.

[0005] Furthermore, the payload control unit receives the receiving level and signal-to-noise ratio margin indicated by the ground station through the measurement and control command, and adjusts the EIRP of the phased array antenna according to the margin situation and coverage range.

[0006] Furthermore, when the downlink signal processing of the baseband processing unit is in information broadcast mode, the satellite will send unique broadcast information generated by combining the user identification and encryption strategy, as well as the spread spectrum codeword used when joining and leaving the network, to the user.

[0007] Furthermore, the phased array transmitting antenna has some channels turned on by default, which are used for beacon transmission within a large coverage area, assisting in high-dynamic user capture or stable tracking adjustment of large-aperture antennas, and the beam width and EIRP can be adjusted by switching the channels.

[0008] A communication method based on a satellite communication system is implemented by a satellite communication system with multi-mode capabilities. The satellite's transmission and reception are both turned on by default. The reception uses a wide-beam receiving antenna to receive commands. The transmission uses a phased array transmitting antenna for beacon transmission, telemetry transmission, or information broadcast. The measurement and control function mode and information broadcast mode are switched by command. The execution of the measurement and control function mode includes the following processes: Step 101: The ground station pre-points to the satellite according to the satellite ephemeris and performs fine-tuning of the pointing direction according to the beacon transmission signal to ensure that the satellite-ground antenna is aligned; Step 102: After the pointing adjustment is completed, the ground station first records the ground station's geographical location and receiving capability, and sends a working mode switching instruction; Step 103: After receiving the command information from the ground station via the wide-beam receiving antenna, the satellite opens all channels of the phased array transmitting antenna to maximize the transmitting power. Step 104: The payload control unit in the signal processing module calculates the angle based on the position of the ground station and the satellite's own position and attitude to achieve staring at the ground station. Step 105: The baseband processing unit in the signal processing module switches to a telemetry fast downlink working mode and selects an appropriate downlink rate based on the ground station's receiving capability. In step 106, the satellite telemetry is quickly transmitted downlink, and the ground station obtains the satellite's telemetry data. During the transmission process, the ground station transmits information about the receiving level and signal-to-noise ratio margin through measurement and control instructions. The payload control unit adjusts the EIRP of the phased array based on the margin, reducing the power consumption of the entire satellite while ensuring the transmission rate.

[0009] Furthermore, the information broadcast mode includes ordinary user broadcast and key user broadcast; The execution of the ordinary user broadcast includes the following process: Step 201: When a user needs to receive broadcast information, he sends his own information to the satellite; different users use a competitive access method; Step 202: After receiving the message, the satellite confirms that the user's information is correctly received and determines whether the user is within the network service range; Step 203: If the network is within the service range, confirm whether the current transmission coverage supports the addition of new users. If it supports the addition of new users, proceed to step 204; if it does not support the addition of new users, proceed to step 205; if the network is not within the service range, exit the process; Step 204: The satellite sends a unique broadcast message generated by combining the user identifier and the encryption policy, and a spread spectrum codeword used when leaving the network, to the user; the user decrypts, receives, and uses the broadcast message according to the encryption policy. Step 205: Determine the relative angle between the satellite and the user, perform a table lookup, adjust the information rate based on the EIRP change caused by the angle change, and close some channels of the phased array transmitting antenna. Step 206: The user calculates based on the received satellite ephemeris and its own position that it is about to leave the coverage area or no longer needs to receive broadcasts, and reports the status in conjunction with the network exit spread spectrum code. After receiving the network exit information, the satellite adjusts its coverage area. The execution of the key user broadcast includes the following processes: Step 301: When a user needs to receive broadcast information, he or she sends his or her information to the satellite; Step 302: After receiving the message, the satellite confirms that the user information is correctly received and determines whether the user is within the network service range; Step 303: If the user terminal is within the network service range, the satellite calculates the link rate based on the user terminal's location and receiving capability, and calculates the broadcast information retention period based on the broadcast information size, and then proceeds to the next step; if the user terminal is not within the network service range, the process is exited. In step 304, the satellite first calculates whether the current agile coverage area supports the addition of new users based on the user location, satellite location, and beam width. If the current coverage area supports the addition of new users, the process proceeds to step 305. If the current coverage area does not support the addition of new users, the process proceeds to step 306. Step 305: The satellite sends the unique broadcast information generated by combining the user identifier and encryption strategy, as well as the spread spectrum codeword used when leaving the network, to the user, and adjusts the dwell period Tn of the beam. The user receives and uses the broadcast information. Step 306: A new coverage beam is generated to serve the new user, and a unique broadcast message generated by combining the user identifier and encryption strategy, as well as a spread spectrum codeword used when leaving the network, is sent to the user. The number of beams changes from m to m+1, where m is the maximum value of the ratio of the satellite coverage to the beam width. The beam retracement period is T0+T1+T2+……+T m , becomes T0+T1+T2+……+T m +T m+1 ; Among them, T1, T2, T m Represent the dwell periods of the first, second, and mth wave positions respectively; In step 307, the user calculates based on the received satellite ephemeris and its own position that it is about to leave the coverage area or no longer needs to receive broadcasts, and reports the status in combination with the network exit spread spectrum codeword; after receiving it, the satellite adjusts the coverage area.

[0010] Compared with the prior art, this application has the following beneficial effects: It has the working modes of rapid telemetry transmission, information broadcasting for key users, and information broadcasting for ordinary users, which can be flexibly switched according to actual needs. It can not only efficiently realize the measurement and control functions and improve the telemetry transmission capabilities, but also meet the information broadcasting needs of different users.

[0011] In terms of information broadcasting, we distinguish between ordinary users and key users and adopt different broadcasting strategies to improve the pertinence and efficiency of broadcasting.

[0012] During user access and exit, flexible adjustments to parameters such as coverage, information rate, and the number of phased array antenna channels and power-offs ensure communication stability and efficient resource utilization. The system's transmission coverage and beam parameters can be dynamically adjusted based on user access, improving system adaptability and communication quality, and better meeting communication needs in diverse scenarios.

[0013] In the design of user access and network exit processes, the system achieves efficient resource management through differentiated mechanisms: During the access phase, users are admitted to the network through a competitive approach. During the access process, the satellite transmits a unique broadcast message generated by combining the user's identity and encryption strategy, as well as a spread spectrum codeword used for network exit, to the user. The user then decodes the encryption strategy and spread spectrum codeword to receive the broadcast message and exit the network. In summary, the satellite's transmit and receive modes are both powered on by default in this application, used to receive commands and transmit beacon signals to assist in the capture of highly dynamic users. The receiver uses a wide-beam antenna, while the transmitter uses a phased array antenna. The default power-up mode is the minimum number of channels, and the phased array antenna can adjust the beam width by switching channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the implementation principle of the satellite communication system in the present invention.

[0015] Figure 2 The figure is a schematic diagram of the phased array transmitting antenna channel layout of the satellite communication system in the present invention.

[0016] Figure 3 Schematic diagram of the application of the satellite communication system in the present invention. DETAILED DESCRIPTION

[0017] The specific implementation of the present invention is described in detail below with reference to specific scenarios.

[0018] Reference Figure 1 The satellite communication system of this embodiment includes a signal processing module, a frequency conversion processing module, a wide-beam receiving antenna, and a phased array transmitting antenna.

[0019] Signal processing module: This module includes a payload control unit and a baseband processing unit. The payload control unit receives ground-based telemetry and control commands and calculates beam coverage and beam pointing based on the satellite platform's ephemeris and pose data, as well as the user's position reported by the baseband processing unit. It also controls the baseband processing unit's downlink transmission rate and the operating mode and beam pointing of the phased array transmitting antenna. Furthermore, the payload control unit switches the phased array antenna's channels based on coverage or telemetry link margin. While meeting existing communication requirements, the payload control unit also adjusts power or beams through the phased array transmitting antenna. The baseband processing unit mainly completes uplink signal processing and downlink signal processing; the uplink signal supports high, medium and low carrier signal processing, and completes the ground station injection instruction parsing, user network access signal processing and user network exit information processing respectively; among them, the low-frequency carrier signal adopts spread spectrum processing method, and different network users complete network exit through different spread spectrum codes; the medium and low carrier signal processing functions can be turned on or off through the injection measurement and control instructions; the downlink signal processing supports flexible switching of multiple modes through the injection measurement and control instructions, including beacon mode, telemetry data transmission mode, and information broadcast mode.

[0020] Frequency Conversion Processing Module: This module includes an upconversion channel and a downconversion channel. The upconversion channel converts the signal transmitted by the signal processing module and sends it to the phased array transmit antenna. The downconversion channel receives the signal through the wide-beam receive antenna, amplifies it, downconverts it, and then sends it to the baseband processing unit.

[0021] Wide-beam receiving antenna: This omnidirectional antenna features a wide beam angle and low gain. It receives wireless signals and sends them to the down-conversion module of the frequency conversion processing module.

[0022] Phased array transmitting antenna: It adopts the form of phased array antenna, which is composed of multiple independent channels and has the characteristics of high output power and fast and flexible pointing. The phased array transmitting antenna receives the signal of the frequency conversion channel of the frequency conversion processing module and outputs it wirelessly. Each channel of the phased array antenna has independent power on and off functions, which can support staring mode and agile mode. The channel layout of the phased array transmitting antenna is as follows Figure 2 shown.

[0023] Reference Figure 3 In the default power-on state, the satellite's transmission and reception are both in operation. Reception uses a wide-beam antenna to receive commands, and transmission uses a phased array antenna as a beacon to assist in the capture of highly dynamic users. The system has multiple operating modes, as follows: (1) Implementation process of measurement and control function mode:

[0024] When telemetry and remote control functions are required, In step 101, the ground station points to the satellite in advance according to the satellite ephemeris, and makes fine adjustments to the direction according to the beacon transmission signal to ensure that the satellite and ground antennas are aligned.

[0025] Step 102: After the pointing adjustment is completed, the ground station first records the ground station's geographical location and receiving capability information, and sends a working mode switching instruction.

[0026] Step 103: After receiving the command information from the ground station through the wide-beam receiving antenna, the satellite opens all the channels of the phased array transmitting antenna to maximize the transmitting power.

[0027] In step 104, the payload control unit in the signal processing module calculates the angle according to the position of the ground station and the position and attitude of the satellite itself to achieve staring at the ground station.

[0028] Step 105: The baseband processing unit in the signal processing module switches to a telemetry fast downlink working mode and selects a suitable downlink rate according to the ground station receiving capability.

[0029] In step 106, the satellite telemetry is quickly transmitted downlink, and the ground station obtains the satellite's telemetry data. During the transmission process, the ground station transmits information about the receiving level and signal-to-noise ratio margin through measurement and control instructions. The payload control unit adjusts the EIRP of the phased array based on the margin, reducing the power consumption of the entire satellite while ensuring the transmission rate.

[0030] (2) Information broadcast mode

[0031] When information broadcasting is performed, there are two specific implementation methods: broadcasting to common users and broadcasting to key users.

[0032] Ordinary user broadcast For general user broadcasts, after the ground station transmits a command to switch to relay mode, the satellite's receiving antenna is in omnidirectional mode. By default, all channels are powered on. Channels can be powered on and off to adjust beam coverage based on actual user access needs. The satellite's receiving end offers wide-angle coverage, and while its capabilities are relatively weak, it can meet access requests from a wide range of users. The transmitting end offers a relatively narrow angle and strong capabilities, allowing for flexible adjustment of coverage. Broadcast content includes satellite information, network access information, and various other broadcast messages.

[0033] When a regular user wishes to receive broadcast information, they notify the satellite of their location, identity, capabilities, and other information through a competitive access process. Upon receiving this user information, the satellite uses the user's identity to determine whether the user is within the network service range. If so, it further determines whether the current transmission coverage can support the new user. If so, the satellite combines the user's identity with the satellite's encryption policy to generate and transmit a network access confirmation message. It also sends the user the spreading code used to deactivate the user's network access. Once the user decrypts the encryption policy, they can receive and use the broadcast information normally. If the current coverage area cannot support the new user, the satellite adjusts the broadcast information rate based on the relative angle to the user, first adjusting the EIRP (equivalent isotropically radiated power) caused by the angle change. It then sequentially disables array elements from the outside to the inside to adjust the coverage. It then notifies the new user of a unique broadcast network access confirmation message and deactivation spreading code generated by combining the user's identity and the satellite's encryption policy. When a user determines they are about to leave the coverage area or no longer need to receive broadcasts, they report their deactivation using their own spreading code. Upon receiving this information, the satellite adjusts the coverage area by powering down the channels of the phased array transmitting antenna. The detailed process is as follows: Step 201: When a user needs to receive broadcast information, he sends his own information (user location, user identification, user capabilities, etc.) to the satellite; different users use a competitive access method; Step 202: After receiving the message, the satellite confirms that the user's information is correctly received and determines whether the user is within the network service range; Step 203: If the network is within the service range, confirm whether the current transmission coverage supports the addition of new users. If it supports the addition of new users, proceed to step 204; if it does not support the addition of new users, proceed to step 205; if the network is not within the service range, exit the process; Step 204: The satellite sends a unique broadcast message generated by combining the user identifier and the encryption policy, and a spread spectrum codeword used when leaving the network, to the user; the user decrypts, receives, and uses the broadcast message according to the encryption policy. Step 205: Determine the relative angle between the satellite and the user, perform a table lookup, adjust the information rate based on the EIRP change caused by the angle change, and close some channels of the phased array transmitting antenna. In step 206, the user calculates based on the received satellite ephemeris and its own position that it is about to leave the coverage area or no longer needs to receive broadcasts, and reports the status in combination with the network exit spread spectrum code. After receiving the network exit information, the satellite adjusts the coverage area.

[0034] Key user broadcast For broadcasts to key users, after the ground station sends a command to switch to relay mode, the satellite's phased array transmitting antenna operates in full array mode, and the channel addition and power-off operations of the phased array transmitting antenna are not performed. When a key user needs to receive broadcast information, it sends its own location, identification, capabilities, cycle requirements and other information to the satellite. After the satellite confirms that the reception is correct and determines that the user is within the service range, it calculates the link rate based on the location and capabilities of the user terminal, and calculates the broadcast information residence period based on the size of the broadcast information. Next, the satellite calculates whether the agile area supports the user based on the user location, its own location and beamwidth. If supported, it combines the user identification and encryption strategy to generate a unique broadcast network entry confirmation information and network exit signal spreading code, and adjusts the minimum residence period Tn of the beam, so that the user can receive information normally. If the agile area does not support it, a new wave position is generated, and the satellite's retracement period is increased accordingly.

[0035] The ground station sends instructions to switch to relay mode, and the transmitting phased array operates in full array mode.

[0036] Step 301: When a user needs to receive broadcast information, he or she sends his or her information to the satellite; Step 302: After receiving the message, the satellite confirms that the user information is correctly received and determines whether the user is within the network service range; Step 303: If the user terminal is within the network service range, the satellite calculates the link rate based on the user terminal's location and receiving capability, and calculates the broadcast information retention period based on the broadcast information size, and then proceeds to the next step; if the user terminal is not within the network service range, the process is exited. In step 304, the satellite first calculates whether the current agile coverage area supports the addition of new users based on the user location, satellite location, and beam width. If the current coverage area supports the addition of new users, the process proceeds to step 305; if the current coverage area does not support the addition of new users, the process proceeds to step 306. Step 305: The satellite sends the unique broadcast information generated by combining the user identifier and encryption strategy, as well as the spread spectrum codeword used when leaving the network, to the user, and adjusts the dwell period Tn of the beam. The user receives and uses the broadcast information. Step 306: A new coverage beam is generated to serve the new user, and the unique broadcast information generated by combining the user identifier and encryption strategy and the spread spectrum code used when leaving the network are sent to the user; the number of beams is increased from m to m+1 (m is the maximum ratio of the satellite coverage area to the beam width), and the beam retracement period is increased from T0+T1+T2+… …+T m , becomes T0+T1+T2+……+T m +T m+1 ; Among them, T1, T2, T m They represent the residence periods of the first, second and mth wave positions respectively.

[0037] In step 307, the user calculates based on the received satellite ephemeris and its own position that it is about to leave the coverage area or no longer needs to receive broadcasts, and reports the status in combination with the network exit spread spectrum code. After receiving the code, the satellite adjusts the coverage area.

Claims

1. A satellite communication system with multi-mode capability, characterized in that: It includes a signal processing module, a frequency conversion processing module, a wide beam receiving antenna and a phased array transmitting antenna; The signal processing module includes a payload control unit and a baseband processing unit; the payload control unit is responsible for receiving the measurement and control instructions from the ground and completing the beam coverage and beam pointing calculation according to the ephemeris and star posture data broadcast by the satellite platform and the user position reported by the baseband processing unit, controlling the downlink transmission rate of the baseband processing unit and controlling the working mode and beam pointing of the phased array transmitting antenna; the payload control unit completes the channel switch of the phased array transmitting antenna according to the coverage range or the measurement and control link margin; the payload control unit performs power or beam adjustment through the phased array transmitting antenna while meeting the existing communication needs; the baseband processing unit The element is used to complete uplink signal processing and downlink signal processing; the uplink signal supports high, medium and low carrier signal processing, which respectively complete the ground station's measurement and control command parsing, user network entry information processing and user network exit information processing; among them, the low-frequency carrier signal adopts spread spectrum processing, and different network users complete network exit information reporting through different spread spectrum codes to avoid information conflicts; the measurement and control commands carried by the high-frequency carrier signal control the opening and closing of the medium and low carrier signal processing functions; the downlink signal processing supports flexible switching of multiple modes through the measurement and control commands, including beacon mode, telemetry data transmission mode and information broadcast mode; The frequency conversion processing module includes an up-conversion channel and a down-conversion channel; the up-conversion channel is used to complete the up-conversion processing of the signal transmitted by the signal processing module and send it to the phased array transmitting antenna; the down-conversion channel receives the signal through the wide beam receiving antenna, completes the amplification and down-conversion, and then sends it to the baseband processing unit; The wide beam receiving antenna is an omnidirectional antenna that receives wireless signals and sends them to the down-conversion channel of the frequency conversion processing module; The phased array transmitting antenna adopts a phased array antenna form and is composed of multiple independent channels; the phased array transmitting antenna receives the signal of the frequency conversion channel of the frequency conversion processing module and outputs it wirelessly.

2. A satellite communication system with multi-mode capabilities according to claim 1, characterized in that: The payload control unit receives the receiving level and signal-to-noise ratio margin indicated by the ground station through measurement and control instructions, and adjusts the EIRP of the phased array antenna according to the margin situation and coverage range.

3. A satellite communication system with multi-mode capabilities according to claim 1, characterized in that: The downlink signal processing of the baseband processing unit is in information broadcast mode. The satellite sends unique broadcast information generated by combining user identification and encryption strategy and spread spectrum code words used when joining and leaving the network to the user.

4. A satellite communication system with multi-mode capabilities according to claim 1, characterized in that: The phased array transmitting antenna has some channels turned on by default, which are used for beacon transmission within a large coverage area, assisting in high-dynamic user capture or stable tracking adjustment of large-aperture antennas, and the beam width and EIRP can be adjusted by switching the channels on and off.

5. A communication method based on a satellite communication system, implemented by a satellite communication system with multi-mode capabilities according to any one of claims 1 to 4, characterized in that: The satellite's transmission and reception are both turned on by default. The reception uses a wide-beam receiving antenna to receive commands, and the transmission uses a phased array transmitting antenna for beacon transmission, telemetry transmission or information broadcasting. The measurement and control function mode and information broadcast mode are switched by commands; The execution of the measurement and control function mode includes the following processes: Step 101: The ground station pre-points to the satellite according to the satellite ephemeris and performs fine-tuning of the pointing direction according to the beacon transmission signal to ensure that the satellite-ground antenna is aligned; Step 102: After the pointing adjustment is completed, the ground station first records the ground station's geographical location and receiving capability, and sends a working mode switching instruction; Step 103: After receiving the command information from the ground station via the wide-beam receiving antenna, the satellite opens all channels of the phased array transmitting antenna to maximize the transmitting power. Step 104: The payload control unit in the signal processing module calculates the angle based on the position of the ground station and the satellite's own position and attitude to achieve staring at the ground station. Step 105: The baseband processing unit in the signal processing module switches to a telemetry fast downlink working mode and selects an appropriate downlink rate based on the ground station's receiving capability. In step 106, the satellite telemetry is quickly transmitted downlink, and the ground station obtains the satellite's telemetry data. During the transmission process, the ground station transmits information about the receiving level and signal-to-noise ratio margin through measurement and control instructions. The payload control unit adjusts the EIRP of the phased array based on the margin, reducing the power consumption of the entire satellite while ensuring the transmission rate.

6. A communication method based on a satellite communication system according to claim 5, characterized in that: The information broadcast mode includes general user broadcast and key user broadcast; The execution of the ordinary user broadcast includes the following process: Step 201: When a user needs to receive broadcast information, he sends his own information to the satellite; different users use a competitive access method; Step 202: After receiving the message, the satellite confirms that the user's information is correctly received and determines whether the user is within the network service range; Step 203: If the network is within the service range, determine whether the current transmission coverage supports adding new users. If it supports adding new users, proceed to step 204; otherwise, proceed to step 205. If you are not in the network service range, exit the process; Step 204: The satellite sends the unique broadcast information generated by combining the user identifier and the encryption policy and the spread spectrum codeword used when leaving the network to the user; Users decrypt, receive and use broadcast information according to encryption policies; Step 205: Determine the relative angle between the satellite and the user, perform a table lookup, adjust the information rate based on the EIRP change caused by the angle change, and complete partial channel closure of the phased array transmitting antenna; Step 206: The user calculates based on the received satellite ephemeris and its own position that it is about to leave the coverage area or no longer needs to receive broadcasts, and reports the status in conjunction with the network exit spread spectrum code. After receiving the network exit information, the satellite adjusts its coverage area. The execution of the key user broadcast includes the following processes: Step 301: When a user needs to receive broadcast information, he or she sends his or her information to the satellite; Step 302: After receiving the message, the satellite confirms that the user information is correctly received and determines whether the user is within the network service range; Step 303: If the user terminal is within the network service range, the satellite calculates the link rate based on the user terminal's location and receiving capability, and calculates the broadcast information retention period based on the broadcast information size, and then proceeds to the next step. If you are not in the network service range, exit the process; In step 304, the satellite first calculates whether the current agile coverage area supports the new user based on the user location, satellite location, and beam width; If the current coverage area supports adding new users, proceed to step 305; if the current coverage area does not support adding new users, proceed to step 306; Step 305: The satellite sends the unique broadcast information generated by combining the user identifier and encryption strategy, as well as the spread spectrum codeword used when leaving the network, to the user, and adjusts the dwell period Tn of the beam. The user receives and uses the broadcast information. Step 306: A new coverage beam is generated to serve the new user, and a unique broadcast message generated by combining the user identifier and encryption strategy, as well as a spread spectrum codeword used when leaving the network, is sent to the user. The number of beams changes from m to m+1, where m is the maximum value of the ratio of the satellite coverage to the beam width. The beam retracement period is T0+T1+T2+……+T m , becomes T0+T1+T2+……+T m +T m+1 ; Among them, T1, T2, T m Represent the dwell periods of the first, second, and mth wave positions respectively; In step 307, the user calculates based on the received satellite ephemeris and its own position that it is about to leave the coverage area or no longer needs to receive broadcasts, and reports the status in combination with the network exit spread spectrum codeword; after receiving it, the satellite adjusts the coverage area.

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