. The Bell System technical journal . Fig. 10—Cathode ray oscillographs, their amplifiers, and the sweep circuit installai meter in the center of the table is the antenna position indicator. Some studies of general carrier fading were made with a pair ofmagnetic counters actuated by trigger gas tubes. These fading count-ers were operated together with automatic recorders so as to maintainthe same integrated average signal output. Since, in the recorder inte-gration, ten-second intervals elapsed between gain readjustments, thefading counters operated to record all quick faces, during th
. The Bell System technical journal . Fig. 10—Cathode ray oscillographs, their amplifiers, and the sweep circuit installai meter in the center of the table is the antenna position indicator. Some studies of general carrier fading were made with a pair ofmagnetic counters actuated by trigger gas tubes. These fading count-ers were operated together with automatic recorders so as to maintainthe same integrated average signal output. Since, in the recorder inte-gration, ten-second intervals elapsed between gain readjustments, thefading counters operated to record all quick faces, during these inter- DIRECTIVITY STEERING FOR FADING REDUCTION 205 vals, which fell below the average output level by any prescribedamount. A photograph of this equipment is shown in Fig. Fig. 11—Field strength recorder and fading counters usedfor fading reduction studies. Results Cathode ray tube observations of selective and also general fadingwere made on the British Post Office stations GBW and GBU usingwobbled carrier. Whenever possible, these observations were made athalf-hourly intervals. For record purposes, arbitrary numbers rangingfrom 0 to 4 were adopted. Zero meant very little fading (five perminute or less) and the most severe cases were represented by 4. Thesefigures were recorded separately for the standard antenna and for therhombus. The difference between the numbers assigned to each an-tenna gave an indication of the fading reduction accomplished. 206 BELL SYSTEM TECHNICAL JOURNAL ^ 35O < 15- D NO REDUCTIONSOME REDUCTIONLARGE REDUCTION i ^ I 0 12 3 4 DEGREE OF SELECTIVE FADING ON HALF-WAVE VERTICAL Fig. 12—Selective fading severity and its reduction at the best positions of therhombic antenna. Stations GBU and GBW, March and April, 1933. Figure
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