Periscope and Sonar

Periscope noun - An optical instrument that provides a view of an otherwise obstructed field.

Sonar and periscope are semantically related in locating device topic. In some cases you can use "Sonar" instead a noun "Periscope".

Sonar noun - A measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return.

Periscope and sonar are semantically related in locating device topic. You can use "Periscope" instead a noun "Sonar".