F-22. The AN/PAS-13A (V2) medium weapon thermal sight (MWTS) (Figure F-14) are silent, lightweight, compact, and durable battery-powered infrared imaging sensors that operate with low battery consumption.
F-23. The MWTS is referred to as singular thermal weapon sight (TWS). The TWS is capable of target acquisition under conditions of limited visibility such as darkness, smoke, fog, dust, and haze. It operates effectively at night and can also be used during the daytime. Infrared light is received through the telescope, detected by an IR sensor, converted to digital data, processed, and then displayed for the user. The MWTS fits the M4 carbine, the M4 modular weapon system, the M16A2, the M16A4 (not shown), the
F-24. The telescope receives IR light emitting from an intended target and its surroundings. The telescope magnifies and projects the IR light onto the scanner on the basic sensor (Figure F-16).
Figure F-16. TWS configurations.
F-25. The scanner reflects the IR light received from the telescope onto the detective assembly. The detective assembly senses the IR light and converts it to video. The sensor's electronics condition the video for display on the LED array. The LED array illuminates the IR image along with the reticle. The light from the LED array is reflected off the scanner to form an image at the eyepiece.
F-26. The technical data for the MWTS are as follows:
• Field of view (FOV) (FOV is halved in zoom mode):
• Telescope magnification (Telescope magnification is doubled in zoom mode):
• Power consumption:
F-27. The TWS has three modes of operation: STANDBY, ON, and EMERGENCY. STANDBY Mode
F-28. When the system is first turned on, the TWS begins a cool down period of approximately two minutes. After the cool down period, the TWS enters the STANDBY mode. During the STANDBY mode, power is not applied to the scanner or display in order to extend the life of the battery.
F-29. When the TWS is in the STANDBY mode and pressure is applied to the eyecup, the TWS switches to the ON mode, and a switch engages to provide power to the scanner and display. After a three-second delay, the system is fully operational.
F-30. When switched to the EMERGENCY mode, the TWS continuously applies power to the entire system. This allows the operator to bypass the three-second delay experienced when switching from the STANDBY to the ON mode. Since power is applied to the entire system while in the emergency mode, battery life is greatly reduced.
Controls and Indicators
F-31. Controls and indicators are as shown in Figure F-17.
• The BRIGHTNESS CONTROL is a nine-position rotary switch with an off detent position (turned fully counterclockwise). The purpose is to turn the system on or off and adjust the brightness of the eyepiece display.
• The CONTRAST CONTROL adjusts the contrast of the thermal image displayed on the raster. It has an automatic and a manual mode.
• The FOCUS RING adjusts the telescope focus from 20 meters to infinity. It requires a manual adjustment and affects both the wide and narrow FOV.
• The FIELD OF VIEW RING is located on the telescope. It has a wide and a narrow FOV. The wide FOV is for using low magnification during target detection, and the narrow FOV is for using high magnification during recognition and engagement.
• The RETICLE SELECT SWITCH selects one of the available reticles depending on the TWS model (medium or heavy). It must be held for two seconds to enable reticle changes. After two seconds, release the switch to cycle to the next reticle. This control is disabled after ten seconds of inactivity.
• The RETICLE ADJUST SWITCH adjusts the reticle aiming features in azimuth and elevation. It is used during zeroing, and it must be held for two seconds to allow changes to be made. After two seconds, each press moves the reticle aiming features one increment. This control is also disabled after ten seconds of inactivity.
• The BLACK/WHITE POLARITY SWITCH selects the polarity of the thermal image displayed on the raster. The initial setting is "white hot." The polarity switch affects the appearance of the target.
• The DIOPTER FOCUS RING adjusts the focus of the raster and indicators to the operator's eye. It ranges from +2 to -6 diopters.
Figure F-17. TWS controls and indicators.
• The display of the TWS (Figure F-18, page F-14) is divided into two portions: the status indicator and the raster. The status indicator indicates low battery, polarity of raster (black hot or white hot), emergency mode selection, system not cooled, zoom, and FOV selected. Displayed on the raster are the thermal scene, reticle zeroing position, and reticle identifier. The TWS provides various reticles corresponding to the systems it is used with. It also provides a reticle for WFV and NFOV.
Figure F-18. TWS display.
• Figure F-19 shows the MWTS reticles with respect to weapon application and FOV.
M1362 Rocket Launcher
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Figure F-19. MWTS reticles. FM 3-23.25
• The M136 reticles provide multiple aim points used for range estimation and target firing (Figure F-20). Each aim point is used at a different range. The range for specific aim points is indicated at the side of the aim point (the number represents 100-meter increments: for example, 3=300 meters). Each aim point is separated by a range of 100 meters. The vertical line of an aim point reflects the width of a 10-foot tank at the specified range. The firing point of each aim line is the point of intersection of the vertical and horizontal lines.
Figure F-20. M136 aim point.
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