A SINGLE SIDEBAND MUSA RECEIVING SYSTEM 319 



The negative sign ahead of this equation takes account of the fact 

 that an increase in the angle 5 requires that more phase will have to 

 be taken from line 8 while less phase will have to be subtracted from 10. 

 It will be noted that for a given change in 5, however, the amount 

 of change of phase is the same absolute amount for the two groups. 

 This indicates that it should be possible to connect the front and rear 

 groups of phase shifters together and drive them as a single unit. 

 To do this it will be necessary to connect the shafts together after 

 they have been moved from their initial position by the amounts 

 given in the above equations. The difiference in phase is 



It will be noted that for a given installation this value is dependent 

 upon the received frequency and will have to be changed when the 

 received frequency is changed. 



In the receivers herein described the phase shifters connected to 

 antenna 9 are not driven. The phase shifters connected to antennas 1 

 to 8 are driven at ratios of 8 : 1, 7 : 1, 6 : 1, 5 : 1, 4 : 1, 3 : 1, 2 : 1 

 and 1 : 1 respectively. The phase shifters of antennas 10 to 16 are 

 driven in the opposite direction at ratios of 1:1, 2:1, 3:1, 4:1, 

 5:1,6:1, and 7 : 1 respectively. A differential gear mechanism is 

 inserted between the two groups. Changing the position of the ring 

 gear of the differential permits a mechanical shift equivalent to the 

 phase shift given in equation (8) to be inserted between the two 

 groups. This change may be made while the drive shafts are in 

 motion. The ring gear drives of the differentials of the four groups 

 of phase shifters are all connected by a common adjustment shaft so 

 as to insure that the monitoring branch does not give a false indication 

 of receiver performance by being set differently than the diversity 

 branches. 



A front view of the phase shifting system is shown on the left of 

 Fig. 6. The vertical shafts drive the individual phase shifting con- 

 densers through spiral gears, of which there are eight inside each of 

 , the lower cast boxes and seven inside each of the upper cast boxes. 

 The horizontal shafts connect to the cam switches used with the auto- 

 matic adjustment feature. A rear view showing a few of the individual 

 phase shifting condensers is given in Fig. 7. Each phase shifting 

 condenser consists of four quadrantal stators each consisting of two 

 plates between which revolves an eccentric circular plate. The rotor 

 plates of the condensers in a horizontal row (see Figs. 1 and 7) are 



