?? ?????????? ???????? ?????
?????? ???? ????????
(
???????????
:
Very low frequency
)? ???????? VLF? ???
??????? ?????? ?????????
[4]
??
????
?????? ???????
?????? ??? 3 ??? 30 ???
????
? ???? ?????
??? ????
?? 100 ??? 10 ???????? ??? ???????.
???? ??????
??? ????
?????? ????? ?? ?????? ????
???????? ???????
? ???? ??? ???? ???????? ???????.
???? ?????
[
???
]
?????
[
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]