Sonar
SOund Navigation And Ranging
Hydrophone
NIC (Network Interface Card)
a television- like display device is called a
node
Softcopy
computers are called silico sepians
ASDIC
It's called the rudder
SONAR True basically in principle but this doesn't fit, and I think that the answer is ASDIC or Anti-submarine Detection Investigation Committee, the former US name.
sonar
You could mean Sonar which is the detection of objects underwater
The name of one such gas leak detection device is called Photoacoustic Multi-gas Monitor. This device and others can be found here: http://www.lumasenseinc.com/EN/products/gas-monitoring-instruments/gas-monitoring/innova-1314.html.
SONAR is actually an abbreviation for SOund Navigation And Ranging. RADAR is correspondingly an abbreviation for RAdio Detection And Ranging. LIDAR is correspondingly an abbreviation for LIght Detection And Ranging.
DIODE
Asdic
a divice that supplies air to underwater swimmers
Whoever felt like it in Florda. So there!
joney willyems made the motion detector