Recent Radio Inventions 



New Patents on Wireless Instruments 

 By A. F. Jackson 



AMONG the most interesting pat- 

 ents of 1915 is No. 1139226, is- 

 sued to E. Raymond-Barker, for 

 a system of radio-telegraphy using two 

 wave-lengths for transmission of a sin- 

 gle message. Instead of sending Morse 

 signals in which the dots and dashes are 

 distinguished by the diflference in dura- 

 tion of impulses, this method uses sig- 

 nals all of the same impulse length but 

 distinguishes between dots and .dashes 

 by sending each at 

 a different wave 

 frequency. That is 

 to say, only short 

 signals which cor- 

 respond in length 

 to ordinary Morse 

 dots are sent, but 

 these are emitted 

 at two different 

 wave lengths, one 

 of which is for 

 dots and one for 

 dashes. 



Figure 1 shows 

 the way in which 

 the invention may 

 be applied to a 

 Poulserr transmit- 

 ter. Here the pow- 

 er lines G supply energy to two oscillat- 

 ing arcs, F F, through suitable imped- 

 ances. The central contacts or levers of 

 two telegraph keys A and Ai are con- 

 nected in the shunt 

 oscillating circuits 

 of the two arcs, 

 and serve to con- 

 nect the arcs either 

 to radiating reso- 

 nant circuits C D 

 or to non-radiating 

 resonant circuits 

 Ci Di. Consider- 

 ing the operation : 



Fig. 1. Raymond-Barker double- wave 

 transmitter 



Fig. 2. Telephonic Receiver for double- 

 wave system 



\\'hen neither key is depressed both arcs 

 are connected to their non-radiating cir- 

 cuits through contacts H H, and gener- 



ate in these circuits oscillations of dif- 

 ferent wave lengths. If it is desired to 

 send a dot the left-hand key is depress- 

 ed ; this connects the left-hand arc to the 

 antenna, and waves of a certain length 

 (say 3,000 meters) are radiated. If a 

 dash is to be sent, the right-hand key is 

 pressed for an instant, and for that time 

 the right-hand arc is connected to the 

 antenna and allowed to radiate waves of 

 its different wave length (say 4,000 me- 

 ters. Thus combi- 

 nations of dots and 

 dashes correspond- 

 ing to the letters 

 of the Morse code 

 are transmitted. 



At the receiving 

 station it is 'neces- 

 sary to pick up 

 signals on either 

 wave length and to 

 indicate that one 

 represents dots and 

 the other dashes. 

 Fig. 2 shows one 

 way in which this 

 may be done : The 

 receiving antenna 

 Bi is connected to 

 two parallel tuned 

 primary circuits, C^ D^, one of which is 

 tuned to the "dot wave" and the other 

 to the "dash wave." Each primary has 

 coupled to it a tuned secondary C6 which 

 acts upon a tikker 

 detector Pi with 

 telephone P and 

 stopping condenser 

 D6. One telephone 

 is held to each ear 

 of the operator 

 and the dots dis- 

 tinguished from 

 the dashes by not- 

 ing which 'phone 

 A simpler way of 



gives the response 



distinguishing the dots and dashes is by 



adjusting the tikker-interrupter speeds 



298 



