Talk:Through-the-earth mine communications

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First paragraph

In the first sentence it is being said that the waves are low-frequency, the second one speaks of high-frequency signals. Is that a mistake or intentional? --Misericordia (talk) 06:20, 22 July 2015 (UTC)[reply]

Radio waves arriving in less than a minute

arriving in less than a minute

Electro-magnetic radiation speeds? Jidanni (talk) 14:29, 8 September 2023 (UTC)[reply]