710 BELL SYSTEM TECHNICAL JOURNAL 



After a survey involving transmitted field strengths and noise measure- 

 ments, a 13-acre plot of tide and water land having ready access to 

 power supply and telephone connections was selected on Point Edwards 

 about one mile south of Edmonds, Washington, and fifteen miles from 

 Seattle. 



Due to the fact that the site for the transmitting and receiving station 

 is under water at high tide, the building housing the radio equipment is 

 of frame construction erected on treated piling. 



The transmitting and receiving antennas, located 200 feet apart and 

 near the building are also supported by piling. Both antennas are of 

 the simple vertical type, the former 80 feet in height and supported by 

 a single pole 110 feet high, and the latter 40 feet in height. A tuning 

 unit is mounted in a weather-proofed box on the receiving antenna pole. 

 The transmission line from the receiving antenna to the receiver^ in the 

 radio equipment building is a special armored and lead covered concen- 

 tric conductor type. 



The equipment at the land station consists of a 400-watt transmitter 

 with a rectifier unit for power supply similar to the type generally used 

 for aviation service. The frequency stability is obtained by the use of 

 a quartz crystal frequency control and will maintain its frequency to 

 better than 0.025 per cent. It is designed for substantially complete 

 modulation of the carrier and under this condition little distortion oc- 

 curs to the speech frequencies. A tuning unit for tuning the trans- 

 mitting antenna to resonance is also housed in the building. 



As shown on the block diagram Fig. 2, a four-wire circuit is used to 

 connect the radio station and the Seattle office where the circuit be- 

 comes two-wire for switching to land subscribers. The equipment in- 

 cludes means for regulating speech volumes; outgoing, so as to always 

 properly load the radio transmitter, and incoming so as to give the 

 shore subscriber the best received volume. A voice-operated device 

 known as the "vodas" provides means for suppressing echoes and sing- 

 ing. This device is essentially the same in principle and in its operation 

 as those used in intercontinental service which have been described in 

 detail in previous publications. In addition to the above units ap- 

 paratus for monitoring and testing is provided. 



The harbor station, moreover, is arranged for remote control opera- 

 tion, equipment being provided so that the transmitter is automatically 

 turned on when the operator inserts a plug in the "Harbor Circuit" jack. 



During operation the transmitter is continuously monitored by 

 means of an auxiliary radio receiver in Seattle tuned to the transmitter 

 frequency. In addition, the two-way portion of the voice-frequency 



1 For a description of the receiver see the followiiitr clijjest. 



