Difference between revisions of "GR - Ranging"
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| − | * [[GR-1]], ground listening set ( formerly geophone) 71-246 | + | * [[GR-1]], ground listening set ( formerly geophone) 71-246. 1924 |
* [[GR-2]] | * [[GR-2]] | ||
* [[GR-3]] sound ranging | * [[GR-3]] sound ranging | ||