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system here employed, however, this steady frequency is practically 

 eliminated so that when there is no speech to be transmitted practically 

 no energy whatever leaves this antenna. Furthermore, in ordinary 



Fig. 5 — A picture of Rocky Point sending antenna 



transmission when there is, say, a 1,000-cycle tone to the voice, this 

 appears in the transmission as two frequencies 1,000 cycles above and 

 1,000 cycles below the carrier frequency. This evidently is an in- 

 effective use of the available frequencies so that one of the so-called 

 frequency side bands in this system is eliminated. In this way a single 

 tone in the voice is represented by a single frequency in the trans- 

 mission from the station. A further frequency economy by the use of 

 the same frequency range for talking in two directions is brought out 

 below. 



