4-62. The sonar operator can use voice communications by moving the MODE switch to COMM position and activating the microphone by 1. depressing a switch on the microphone 2. turning a panel switch 3. depressing a foot switch 4. speaking into a voice-activated microphone 4-63. When the sonar set operates in TEST mode, system voltages and functions are sampled to see if they are within preset limits. How does the operator know when a preset limit is exceeded? 1. A special blip appears on the CRT 2. A fault indicator lights up 3. A sound is audible in the headset 4. A meter indicates the discrepancy 4-64. When the sonar set is operating in BT mode, the recorder plots temperature on what part of the moving chart? 1. Vertical axis 2. Horizontal axis 3. Left side 4. Right side 4-65. When the sonar set is operating in BT mode, the recorder plots dome depth on what part of the chart? 1. Top 2. Bottom 3. Horizontal axis 4. Vertical axis 4-66. The recorder RANGE mode provides which of the following indications? 1. A continuous digital display of target range 2. A series of range scale marks of target range 3. A strip-chart display of target range 4. A selectable digital display of target range 4-67. The recorder ASPECT mode provides which of the following indications? 1. A strip-chart display of target echoes of varying intensity 2. A strip-chart display of target echoes of constant intensity 3. A stylus sweep that draws the outline of the target on a chart 4. A stylus sweep that draws half of the target outline on one side of the chart and the other half of the target outline on the other side of the chart 4-68. Which of the following is a practical means of detecting a submerged submarine from an in-flight aircraft? 1. Detecting radio waves reflected from the submarine’s surface to the aircraft 2. Detecting acoustic waves reflected from the submarine’s surface to the aircraft 3. Detecting disturbances in the submarine’s magnetic field caused by interaction with the earth’s magnetic field 4. Detecting disturbances in the earth’s magnetic field caused by the submarine’s magnetic field 4-69. Magnetic lines of force are essentially undistorted in passing from water to air because both media have approximately the same 1. reactance 2. retentivity 3. permeability 4. dielectric strength 4-70. The angle of change in the east-west direction of the earth’s natural magnetic field is known as the 1. angle of variation 2. angle of incidence 3. entry angle 4. dip angle 29