LOCATING AND REPORTING TARGETS

[Music] [Applause] e thousands of miles of Coastline and all of it an open Skyway for enemy planes with long range bombers and Seaborn aircraft they can strike at our War Industries Transportation centers and other strategic points they may come at any time from any direction to be forewarned of this challenge to our defenses several radio detector devices have been developed one of which is the scr 270 this device is used to locate and track enemy aircraft before they come near their objective the scr 270 is effective under all climatic and atmospheric conditions and can be used at night as well as during daylight in this training film we are mainly concerned with two parts of the equipment the oscilloscope and the antenna shortwave beams known as the output signal are sent into space from the antenna the output signal appears on the oscilloscope screen as a stationary signal when the short waves meet a target for example a plane a small fraction of them are reflected back to the same antenna the reflected waves appear on the oscilloscope screen like this this is called the target echo or image as the antenna swings around this Echo reaches a maximum height at that maximum a reading is taken from the scale at the base of the antenna this is the aouth scale and it indicates the direction from which the target Echo is coming by transposing this scale scale to a map the direction of the target can immediately be plotted for example 90 on the scale is 90 on the map the distance to a Target can be read from a dial in miles a ruler scaled in miles is used to spot the point on the map in this case 60 Mi thus the exact location of the target is plotted the operating crew consists of four men to the left is the oscilloscope operator who works the oscilloscope controls beside him is the range reader who calls out the distance to the Target the Third third man is the asouth reader who reads the scale at the base of the antenna and beside him is the platter who marks the targets on the map each of these men is trained to do every one of the four jobs the oscilloscope screen can be called the camera eye of the scr 270 beneath it are four knobs that control the reception of signals the one on the far left turns on the oscilloscope and as soon as it is ready for reception the operator turns the knob on the far right this is the intensity control and adjusts for the brightness of the signals being received just to the left of the intensity knob is the focus control which sharpens the signal image on the screen both of these controls are manipulated at the same time since brightness and sharp can be judged simultaneously a viewing tube is used to mask out any outside light which may interfere with the operator's observation of the signals the tube is used at all times except during practice periods the third control from the right is the vertical adjuster and is used to Center the picture on the screen the fourth control on the far left in addition to being the onoff switch is the sensitivity or signal height control it is set to give a maximum Echo signal 1 to 1 and half in high below these four knobs is the range dial turning this control will move the image from side to side the distance on the screen between the output signal and the Echo corresponds to the distance between the station and a Target when the left edge of the echo signal is lined up with the hairline the distance to the Target can be read in miles a verer is used for finer adjustments when the left side of the output signal is lined up with the center hairline the distance in miles should read zero since the output signal originates at the station this must be checked before operation in order to get accurate distance readings finally there is the rear stat which controls the rotation of the antenna the power is turned on by the black button switch switch at the left the red button turns it off with the power on the rat controls the starting stopping direction and speed of rotation with the pointer in down position the antenna is motionless turning the control clockwise rotates the antenna in a clockwise Direction the speed of rotation being increased as the pointer is turned higher on the dial for counterclockwise rotation the rear start pointer is turned to the other side of the dial a quick shift to zero will not stop the movement abruptly it will only allow the antenna to Coast a quick stop is made by shooting the pointer high on the opposite section of the dial and then shifting it back to zero these are all the oscilloscope controls the antenna rear stat the range dial and the four signal controls intensity Focus vertical position and sensitivity when setting up the oscilloscope for locating targets the operator adjusts the focus and intensity and positions the image he then sets the sensitivity and rechecks the focus as soon as this is done he checks the zero distance reading this constant streaky pattern is called hash and is characteristic of the equipment it does not enter into the actual business of locating targets the operator starts the antenna a Target image first appears as a break in the Baseline here's one now as the antenna swings the echo reaches a maximum and then diminishes the bobbing effect of the echo signal indicates a moving Target this effect is not always registered so sharply it definitely contrasts with the peak of appearing alongside of the output signal which may indicate a stationary Target possibly a steel Tower or a tall building swinging the antenna still further the operator picks up another signal from this one it can be seen how the number of planes can sometimes be estimated close examination will show that this signal is actually made up of three individual Peaks indicating three planes once more the antenna swings and this time the operator finds an area where there are several targets at various distances from the station each one of these Peaks indicates a Target through experience the operator learns the sensitivity of the reat control so that he is able to keep the antenna right on the trail of a moving Target he also learns to approximate the direction and speed of a Target the operator tracks single targets for practice during his training period in tactical employment the antenna moves back and forth at a uniform speed and the crew plots all Targets within a definitely assigned sector without stopping the antenna the asouth reader sees that the antenna covers the assigned sector when the end of the arc is reached he calls out reverse here is how the crew operates as it searches an assigned area the operator works the oscilloscope controls while watching the screen the asouth reader keeps his eyes glued to the asouth scale the range reader stands by to read the distance and the plotter is ready to chart the points the operator spots an echo signal and calls ready he lines up the left side of the echo signal with the center line and when it reaches a maximum he calls read the asouth reader notes the number on the scale 105 the range reader calls out the distance to the Target 23 the plotter swings the ruler to 105 and marks the point at 23 he then phones the point to the information center where targets are marked on a large map called a radar board the operating crew does not concentrate on a single portion of the sector all Targets are plotted and the information relayed to the radar board plotters The Continuous and systematic search of a complete sector makes it possible to cover a wide area with a chain of overlapping sectors now let's see how a crew operates in a tactical [Music] [Music] situation 72 four four 73 opal 39 reverse ready read 603 Noble 4 One ready three 50 72 PA 35 62 and 63 are enemy clear the board for Action when it is determined that there is a flight of enemy planes Interceptor units are immediately sent [Music] out crew in the meantime continues to track and report all Targets that appear in their sector ready GRE 68 71 fall 9 8 71 Paul 98 the degree of skill the crew members of the scr 270 obtain will be an important factor in fighting against the onslaught of Nazi and Plains and will help to blast them out of the [Music] sky