Recording of HADES-D satellite
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This dataset is an RF recording of the 436.666 MHz signal of the amateur satellite HADES-D, developed by AMSAT-EA. The recording was done on 2023-12-09 during an almost overhead pass in Madrid (Spain). A handheld 7 element yagi antenna and a USRP B205mini were used. The recording is split into two files because the recording software stopped and was restarted during the pass, leading to the loss of about one minute of data. The USRP was set to the maximum gain. For some seconds at the beginning of the first recording and at the end of the recording, a 50 ohm dummy load was connected to the USRP B205mini instead of the antenna. This can serve to do a coarse absolute power calibration by using the known noise figure of the USRP. The recording was done at 16-bit IQ, 4 Msps, at a frequency of 436.5 MHz using GNU Radio. The data was saved to a GNU Radio metadata file with detached headers to save the timestamps produced by the USRP (whose time was set using the recording laptop clock, which was synchronized by NTP). The recording was then formatted SigMF format. The original metadata headers are included with the .hdr extension. The HADES-D signal was Doppler corrected and decimated to 32 ksps. The result is included in the dataset, in the files that contain 32ksps in their name.
本数据集为AMSAT-EA开发的业余卫星HADES-D的436.666 MHz射频（Radio Frequency, RF）信号录制数据。本次录制于2023年12月9日完成，对应卫星在西班牙马德里上空近乎天顶的过境时段。本次录制采用手持式7单元八木天线及USRP B205mini通用软件无线电外设（Universal Software Radio Peripheral, USRP）。由于过境期间录制软件意外中断并重启，本次录制被拆分为两个文件，约1分钟的数据因此丢失。该USRP设备被设置为最大增益模式。在第一段录制的起始时段与第二段录制的结束时段，均将50欧姆假负载连接至USRP B205mini以替代天线，可借助USRP已知的噪声系数完成粗略的绝对功率校准。本次录制采用GNU Radio开源软件无线电平台完成，采样参数为16位同相正交（In-phase and Quadrature, IQ）数据、4兆采样每秒（Msps），中心频率设置为436.5 MHz。录制数据被保存为分离表头的GNU Radio元数据文件，以保留USRP生成的时间戳——USRP的系统时间通过录制笔记本的时钟设置，而该时钟已通过NTP（Network Time Protocol，网络时间协议）完成同步。随后该录制文件被转换为SigMF（Signal Metadata Format）格式，原始元数据表头以.hdr扩展名保存并随数据集一同提供。HADES-D信号已完成多普勒校正，并被抽取至32千采样每秒（ksps）的采样率，处理后的结果已包含在本数据集中，对应文件名中带有“32ksps”字样的文件。
