Detailed text transcripts for TV channel - CNN - 20180708:19:10:00
Frequency you can communicate through stone. do you know anything about hey phones, and do you know if some of the british divers there might be familiar with that technology? >> yes, it's solid state technology. we do have a replacement, digital version, but those who were shipped off at short notice, they're pretty effective. they give voice communication, as you say, through the deep rock of caves. it could be set out on a mud bank or a rocky sort of substraight within the cave. an equivalent set has to be positioned, ideally, vertically above in order to get a good signal. its key feature ...
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