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使用软件定义的无线电探测地震波

我了解物理和海浪,但我是一个完全新手在这个话题。我想知道这是典型的s波的频率范围,p波和表面波。

我的想法是使用软件定义的无线电检测任何地震事件,但我不确定如果任何外围设备可以检测这些正常的波。例如,一个HackRF外围1 MHz到6 GHz之间工作。据我所知,较低的频率低于3兆赫旅行有效地面波。因为我想知道我可以检测任何通过介质频率(0.3 - 3兆赫)。例如,HackRF检测1 MHz至6 GHz频率操作,所以它可以发现一些东西,但我不知道“寻找”。

MF过高,是否有任何机会通过谐波检测什么?

回答

我希望我理解你的问题,我认为有一些困惑关于频率范围和wave-types。地震波加速度的物质转移动能从震源(如地震、爆炸或环境噪声)热量。类似于声波的振动表面的如乐器组的空气运动和压缩空气的分子转移浪潮,最终达到e。g耳膜。然而,增加的复杂性,在固体物质一些额外的弹性,当你注意到。波可以进步不仅是压力波(P)也在边界剪切波(S)和特殊的表面波可以形成,通常的高振幅。地震波的发展取决于地球的弹性性质。很大一部分的术语用于地震波类似于我们如何描述电磁波。如频率、阻尼和共振有关地震波。然而,范围非常不同,电磁波,声波表现不同。地球是一个有效的过滤,甚至瞬态能量,包含高频,仅限于低频率,通过大地进步。 Ground wave propagation, as know from radio signals, are different from the properties of seismic surface waves. An interesting coincidence is that wavelengths can be in the same magnitude, but that is because radio waves progress about 100.000 times faster than crustal seismic waves. [![Charles J. Ammon Penn State University][2]][2] *A figure, prepared by Professor Charles J. Ammon, shows the ranges of frequency and amplitude. Source [here][1]. The amplitude and period have a large range, that's why prefixes as milli or micro can be used and a logarithmic scale is used for amplitude.* In shallow active reflection seismic surveys, we sometimes can use frequencies up to maybe 200Hz, but in the range the penetration depth is very small. For very local events, e.g. in mines and infrastructure frequency range up to 500-1000Hz might be used. Most energy for P and S waves used in teleseismics are in the range of a few Hertz and maybe up to 10-20Hz. Surface waves have the interesting property that the velocity depends on the frequency because low frequency content is affected by deeper elastic properties whiles high frequency content is more affected by shallow geological features. This is used for lithosphere tomography with rather good vertical resolution. The [frequency range][3] is 0.005Hz and up to 0.5Hz. This is the frequencies that you can actually [see][4] in ground motions caused by earthquakes, if you take resonance in consideration. [Normal modes][5] are often in the range 0.3 - 1mHz. (m, as in milli, not M, as in Mega). That is frequencies about one billiard times lower than some radio frequency bands. Another thing to remember in the context of Software defined radio, is that there is no carrier wave for seismicity. When seismologists talk about frequency, we mean energy content of a signal. We are looking at the convoluted wavelet, not continuous signals. If you are interested in working with earthquake detection and to improve algorithms of signal processing of seismic waves, I'd suggest you to take a look at the [Obspy][6] package, there are some nice examples and tutorials that can get you started. There are also some project where people are constructing open architecture seismometers, eg the [Raspberry Shake][7]. For less than $100 or so you can build a seismograph and start to monitor local seismic events. Most geophones work by transfering ground acceleration to an induced electric current in a coil. It's very possible that inspiration from other fields of signal processing, as in [Software defined radio][8] can improve seismic techniques in future. It is always great to get inspiration from other fields of research. [1]: http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/seismometers.html [2]: http://i.stack.imgur.com/se1oV.gif [3]: http://www.seismo.com/msop/msop79/rec/fig_1.2.1b.gif [4]: http://www.bbc.com/news/world-asia-36061715 [5]: https://en.wikipedia.org/wiki/Normal_mode#Earth [6]: https://github.com/obspy/obspy/wiki [7]: https://www.raspberrypi.org/blog/raspberry-shake-personal-seismograph/ [8]: https://en.wikipedia.org/wiki/Software-defined_radio

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