纳卫星星载发射机的设计与实现

Design and implementation of transmitter for nano-satellite

以纳卫星研究项目为背景,设计和实现了适用于纳卫星的新型发射机。该发射机具有功耗低、重量轻、体积小、灵活性高等特点。根据指标要求,理论计算发射功率要求,研究发射机的结构,并详细讨论芯片选型。星载发射机的基带处理部分由现场可编程门阵列(FPGA)实现,完成信道编码、扩频、BPSK调制;输出采样经过数/模转换、滤波网络、正交调制、功率放大、功率分配等模块后,通过天线辐射出去。设计了FPGA软件,完成外部使能检测、芯片在线配置和BPSK调制。在一块印制电路板上实现发射机设计,最后通过实际地面测试,功耗约为2.5 W,重量约为16 g,尺寸为80 mm×38 mm×15 mm,发射功率为24 d Bm,表明设计结果满足尺寸、重量、发射功率等指标要求。

A new type of transmitter for nano-satellite is designed and implemented in this paper for the research project of nano-satellite. The transmitter has the characteristics of small size,light weight,low power consumption and high flexibility. According to technical requirements,minimum transmit power is calculated theoretically,the transmitter structure is studied and chip selection is discussed. The baseband digital signal processing,such as channel coding,spread spectrum and BPSK modulation,is realized by means of field programmable gate array（FPGA）. The output samples are sequentially processed by the modules of DAC,filtering network,quadrature modulation,power amplification,power distribution,and finally transmitted by antenna. The FPGA software was designed to complete external signal detection,online chip configuration and BPSK modulation. The transmitter was implemented on a printed circuit board. The test results showed that the transmitter′s weight is 16 g,size is 80 mm× 38 mm× 15 mm,transmitting power is 24 dBm and power consumption is only 2.5 W,which validate the practicability of the proposed transmitter.