. The Bell System technical journal . used to display the trans-mitted pulse and received echoes. This horizontal sweep, however, differsfrom the simple sweep of earlier radars in several respects. First, thecentral portion of the sweep is expanded to permit more accurate viewingof signals appearing within this region; second, a downward deflectioncalled the range notch is produced in the approximate center of the ex-panded section; and third, the circuits are so arranged that the notch 32 BELL SYSTEM TECHNICAL JOURNAL remains centered as the range unit phase shifters are rotated thus causinga
. The Bell System technical journal . used to display the trans-mitted pulse and received echoes. This horizontal sweep, however, differsfrom the simple sweep of earlier radars in several respects. First, thecentral portion of the sweep is expanded to permit more accurate viewingof signals appearing within this region; second, a downward deflectioncalled the range notch is produced in the approximate center of the ex-panded section; and third, the circuits are so arranged that the notch 32 BELL SYSTEM TECHNICAL JOURNAL remains centered as the range unit phase shifters are rotated thus causingall of the signals (rather than the notch) to move across tlie screen. Rangemeasurement is made by rotating the range unit handcrank to place thedesired signal in the center of the range notch on the indicator. Thistype of presentation has several advantages. It permits the full 100,000-yardrange to be viewed at all times so that new targets may be immediatelydetected, and permits accurate viewing of the desired target in the expanded. Fig. 27—Mark 6 ik. 4—Range presentation center of the sweep where best focus is obtained. For smooth range track-ing it is only necessary for the operator to rotate the range unit hand crankto keep the desired signal centered in the range notch. A block diagram of the range measuring system, together with the circuitsused to obtain the cathode ray indicator presentation described above, isshown in Fig. 28. A base or reference oscillator generates a sine wave kc, one cycle of which corresponds to a radar range of 100,000 wave, after amplification, is applied to a non-Hnear coil pulse gene-rator which generates short pulses (one positive and one negative pulse ^ Magnetic Generation of a group of Harmonics, E. Petersen, T. M. Manlev L RWrathall—August 1937, B. 5. r. 7., October 1937. FIRE-CONTROL RADARS FOR NAVAL VESSELS 33
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
