21. Examples are sonar , radar, lidar, laser, scuba. 22. Since 2000, whale strandings frequently occurred following military sonar testing. 23. Other early examples were analyzing sonar data to detect Russian submarines. 24. Long-range sonar uses low frequencies to minimise absorption effects. 25. Modern torpedoes are generally fitted with an active / passive sonar . 26. Sonar can be used to detect frogmen and other scuba divers.27. An explanation of their operation is given in synthetic aperture sonar . 28. Longer range sonars are more adversely affected by nonhomogenities of water. 29. The submarines carry the Thales Underwater Systems Type 2054 composite sonar . 30. Avoiding sonar inevitably requires a change in behavior or surfacing pattern. 