A Playback System for Long-term Analog Tape Recordings of Ocean Bottom Seismographs
A Playback System for Long-term Analog Tape Recordings of Ocean Bottom Seismographs
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海底地震仪长期模拟磁带记录回放系统
DOI：
10.4294/zisin1948.37.4_633
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
N. Hirata
中科院分区：
文献类型：
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作者：
T. Urabe;N. Hirata
研制了海底地震仪（OBS）网络直接模拟磁带录音的自动回放系统。该系统利用一台配备高速a - d转换器的小型计算机。在直接模拟记录方法中，地面运动被连续记录在一个小型盒式磁带中10至25天，并以数百倍的记录速度再现。首先，OBS模拟磁带的输出经过整流、低通滤波，然后以相对较慢的13 Hz采样率（每地震秒采样数）连续数字化，并存储在磁盘中。在数字化记录中，满足指定标准的事件被检测出来，并被放在每个OBS的列表中。通过交叉引用网络中所有OBS的列表来消除非地震事件。其次，以60至150赫兹的快速采样率从模拟磁带中再次数字化列出的部分地震。重新数字化是根据地震表制定的时间表自动完成的。通过数值重采样，将数字化地震资料文件的采样率与各OBS时钟相统一。所有海底地震仪的地震数据文件被组装和编辑成一个多站点数据文件，其中所有站点的记录被引用到一个共同的时间轴上，就像遥测网络数据一样。它是由一个D-to-A转换器和一个图表记录器可视化。这种目视记录的格式便于提取地震阶段以便确定震源，因为在不同台站获得的波形之间的相关性是明显的。这导致比传统方法更准确地测量到达时间；读取单站记录。数字化的数据文件保存在磁带中。虽然该系统主要用于处理地震台网数据，但它也适用于其他类型的数据，如爆炸实验数据。该系统大大提高了OBS数据处理的自动化程度和速度。
An automatic playback system for direct analogue tape recordings from an ocean bottom seismograph (OBS) network was developed. The system utilizes a mini-computer equipped with a high speed A-to-D converter. In the direct analogue recording method, ground motion is recorded continuously for 10 to 25 days in a compact-cassette tape and is reproduced at several hundred times recording speed. First, the output of the analogue tape from an OBS is rectified, low-pass-filtered, then digitized continuously at a relatively slow sampling rate of 13 Hz (samples per seismic second) and stored in a magnetic disk. In the digitized record, the events satisfying a specified criterion are detected and put on a list for each OBS. Non-seismic events are eliminated by cross-referencing the lists of all OBS's in the network. Secondly, portions of the listed earthquakes are digitized again from the analogue tapes at a fast sampling rate of 60 to 150 Hz. The re-digitizing is done automatically according to the schedule made from the lists of earthquakes. The sampling rates of the digitized earthquake data files are unified with reference to each OBS clock by numerical resampling. The earthquake data files from all the OBS's are assembled and edited for each earthquake to make a multi-station data file in which the records of all the stations are referred to a common time axis like telemetered network data. It is visualized by a D-to-A converter and a chart recorder. This format of visual records facilitate picking up earthquake phases for hypocenter determination because the correlation of the waveforms among those obtained at different stations are apparent. This leads to more accurate measurement of arrival times than by the conventional method; reading a single-station record. The digitized data files are preserved in magnetic tapes. Although the system is intended primarily to process earthquakes network data, it is also applicable to other kinds of data such as those by explosion experiments. This system has automated and speeded up the OBS data processing significantly.