Development of an intelligent receiver for a planetary probe

本研究的目的是开发一种智能接收机，有效地传输地球卫星和行星探测器观测到的波数据，数据压缩方法的开发和评估是在1997年由一个IBM/PC兼容板计算机，A/D转换器，数字信号处理器（DSP）等组成的智能接收机的原型。提出了一种变块长子带编码的数据压缩方法，并对该方法的压缩率和处理速度进行了评估，验证了该方法的有效性。1998年研制了一种基于数字下变频器（DDC）的智能扫频接收机。DDC将A/D转换数据的频率数字地转换为较低频率。首先，将所观察到的频率转换为中心频率等于本地频率的 * 50 kHz带宽的分析信号。通过上述数据压缩方法可以有效地发送该转换波形。可以使用快速傅立叶变换（FFT）来分析它们的频谱。研制了一种频率高达2 MHz、分辨率约为200 Hz的频率分析仪，其数据处理速度比模拟式Geotail扫频接收机（SFA）快几十倍，并成功地研制了一种高分辨率、高速度的频率分析仪和数据压缩方法。这些结果可以用于未来的行星探测器。

The objective of this research is to develop an intelligent receiver which efficiently transmits wave data observed by an earth satellite and planetary probe.Development of data compression method and its evaluation was performed by an prototype of an intelligent receiver which composed of an IBM/PC compatible board computer, A/D converter, Digital Signal Processor (DSP), etc in 1997. An data compression method by variable block-length subband coding is developed, its compression rate and processing speed for various waveforms observed by the Geotail satellite using CPU and/or DSP were evaluated, and its usefulness was confirmed.A sweep receiver for the intelligent receiver using Digital Down Converter (DDC) was developed in 1998. The DDC digitally convert a frequency of A/D converted data to a lower frequency. First, observed frequencies are converted to a analytic signal of a *50kHz bandwidth whose center frequency is equal to a local frequency. This converted waveform can be efficiently sent by the data compression method shown above. Their frequency spectra can be analyzed using the Fast Fourier Transform (FFT). A frequency analyzer for frequencies up to 2MHz with about 200Hz resolution has been developed and can process data several tens times faster than the analog-type Geotail sweep receiver (SFA).A high resolution and high speed frequency analyzer and data compression methods have been developed successfully. These results could be used for planetary probes in the future.