TELEGRAPHY — HILLIS 203 



be located in this building. The radio equipment is designed to work 

 from single-phase, 60-cycle commercial power. In the event of a com- 

 mercial power failure, the radio load will be automatically transferred 

 to the output of a storage-battery-driven alternator or vibrator. At 

 the same time a gasoline-engine-driven alternator is automatically 

 started and after the engine has reached operating speed, the radio 

 load is transferred to this power supply and remains there until the 

 commercial power is restored. A floating rectifier will keep the storage 

 battery charged. 



Strategically located maintenance men will service the equipment 

 at three or four radio relay towers. They will be furnished with an 

 automobile containing an assortment of testing equipment and spare 

 parts, although it is planned to do most of the repair work at the 

 maintainors headquarters. 



A service channel has been provided for testing purposes between 

 the terminals and includes all the radio relay stations. This channel 

 is independent and does not interfere with the traffic channel. 



Fault-finding equipment will be provided at the terminals so that 

 the operating condition of each unattended tower repeater may be 

 quickly determined. A preselected audible frequency will be sent 

 by the terminal, which, by means of a band pass filter, will be received 

 by the repeater station selected. This signal will be sent back to 

 the terminal station after certain intelligence has been added and 

 will indicate operating conditions of the equipment at that station. 



Terminal towers will contain radio equipment which will translate 

 the ultrahigh radio frequencies to the 300-150,000 cycle telegraph 

 carrier. These frequencies are sent to the main office of the telegraph 

 Company over a coaxial cable and by means of frequency transla- 

 tors and filters are separated into the 32 voice bands. The voice 

 bands are either patched to various groups of carrier channel termi- 

 nal equipment or to voice bands of other carrier systems. 



Some of the terminal towers will not only contain the radio equip- 

 ment, but the telegraph carrier voice band translating equipment as 

 well. The conditions at Washington, D. C, make this arrangement 

 more practical. At the tower, the radio frequencies will be translated 

 to the carrier frequencies. These in turn will be broken down to the 

 32 voice bands and the individual voice bands transmitted over cable 

 pairs to the main office where only the telegraph channel terminals 

 will be located. 



The radio relay network is being laid out on a triangular basis 

 as far as possible so that with the failure of any one leg communica- 

 tion may be quickly reestablished by using stand-by facilities on the 

 other two legs. 



