select which signal goes to which pen on the recorder. The MAD AUX POWER-OFF switch supplies primary ac power to the SAD system and the selector control subassembly. The INHIBIT light indicates an inhibit signal from the SAD system. MX-8109/ASA-71 SELECTOR CONTROL SUBASSEMBLY.— The MAD signals from the MAD control and the SAD mark from the MAG VAR indicator are routed to this subassembly. The selector control panel selects which one goes to which pen, and the subassembly routes the signal to the proper pen. A SAD mark 1-kHz tone is generated by the subassembly to be supplied to the ICS system for the SENSOR operator. RO-32 MAD Recorder The RO-32 recorder makes a hardcopy of MAD contacts and SAD marks. This recorder has two styluses, one black and one red, to differentiate between the two. The chart drive is removable to enable the operator to remove and replace the paper tape. here are three knobs on the faceplate. The first switch is the ON/OFF switch. The second controls the intensity of the internal lights. The third knob selects the operate mode along with the pen calibration modes. When B is selected on the mode knob, the black pen should trace along the zero line on the paper tape. When the mode knob is switched to the +, the black pen should go to +4. When this knob is switched to the R position, the red pen traces along the zero line. When it goes to the +, the red pen should swing to the +4 line. Both pens are adjustable to these settings. SONOBUOYS Learning Objective: R e c o g n i z e  t he classifications and the operating principles of sonobuoys currently in use. The detection, localization, and identification of submarines is the primary mission of the Navy’s airborne ASW forces. The ability of the Navy to complete this mission is dependent upon the sonobuoy. The sonobuoy has undergone a great deal of change in the past 25 years. These improvements have provided the fleet with large numbers of very reliable sonobuoys that perform various missions. The sonobuoys are dropped from the aircraft into an area of the ocean thought to contain a submarine. The pattern in which the sonobuoys are dropped usually involve three or more buoys. The sonobuoys detect underwater sounds, such as submarine noise and fish sounds. These sounds modulate an oscillator in the RF transmitter portion of the sonobuoy. The output of the transmitter is a frequency modulated VHF signal that is transmitted from the antenna. The signal is received by the aircraft, and then detected and processed by a sonobuoy receiver. By analyzing the detected sounds, the ASW operator can determine various characteristics of the detected submarine. The use of several sonobuoys operating on different VHF frequencies in a tactical pattern enables the ASW operator to localize, track, and classify a submerged submarine. Each sonobuoy type is designed to meet a specific set of specifications that is unique to that particular sonobuoy. Even though different manufacturers, the specifications and operational performance characteristics are the same for all manufacturers. There are differences in the methods used for prelaunch selection of life and depth settings from one manufacturer to another for the same sonobuoy types. These differences are found in the Sonobuoy Instruction Manual, NAVAIR 28-SSQ-500-1. You should refer to this manual prior to storing, handling, or disposing of sonobuoys. Sonobuoy Frequency Channels Certain sonobuoy designs are equipped with an electronic function select (EFS) system. The EFS system provides each sonobuoy with a selectable 99-channel capability. EFS also provides each sonobuoy with 50 life and 50 depth setting selections. The operator must reset all three settings any time any of the three are changed. With the older type of sonobuoy, the transmitter frequency is preset at the factory. here were 31 different channels used within the 162.25- to 173.5-MHz band. Transmitter frequency is designed to be within ±25 kHz. temperature extremes in hot or cold storage adversely affect these tolerances, especially in sonobuoys that are older. 4-24 OPERATING PRINCIPLES