| The micro-nano-satellite is small in size and light in weight,and the on-board system must meet the requirements of miniaturization and low power consumption.The measurement and control system is one of the most important subsystems of the micro-nano-satellite,and it is responsible for establishing the communication link between the satellite and the ground.In this paper,we investigate the miniaturized digitalization scheme of the micro-nano-satellite measurement and control system,and design the integrated scheme of micro-nano-satellite measurement and control digital transmission,the on-board antenna beamforming scheme,and the transponder baseband signal processing scheme,as follows:(1)According to the demand of miniaturization of micro-nano-satellite,integrate the micro-nano-satellite measurement and control system with the digital transmission system,adopt a non-coherent measurement and control system,design an integrated measurement and control digital transmission scheme,develop the data frame format of uplink and downlink and design the speed and range measurement algorithm;(2)The microstrip array antenna is used in the on-board antenna part,and the digital beamforming algorithm of the array antenna is mainly studied.To address the shortcomings of the conventional beamforming algorithm that the primary flap is too wide and the low secondary flap cannot be controlled,a digital beamforming scheme based on genetic algorithm is designed for the array antenna.The scheme can minimize the width of the main flap and improve the directionality of the antenna with the minimum number of array elements,while suppressing the side flap level to achieve a better beamforming effect than the conventional algorithm;(3)The QPSK modulation and demodulation scheme is used for the digital baseband of the measurement and control system.A square root raised cosine roll-off filter is designed at the transmitter side to further improve the transmitting efficiency and inter-code interference resistance by filtering out the high frequency harmonics of the baseband signal.An improved polar Costas loop is designed at the receiver side to improve the fast carrier locking capability of the micro-nano-satellite receiver under high dynamic conditions in space,and the Gardner loop is used to synchronize the code elements of the measurement and control system to improve the stability and reliability of the measurement and control system.The article completes the integration simulation of the digital measurement and control system of the micro-nano-satellite and the FPGA implementation of the digital baseband part of the transponder,and verifies the feasibility of the new integrated micro-nano-satellite measurement,control and digital transmission scheme.The new integrated system can meet the requirements of miniaturized and low-power micro-nano-satellite use. |
