Radio age research, manufacturing, communications, broadcasting, television (1941)

don of the CTC system were developed, manufactured and installed by the Radio Corporation of America through its RCA International operation. The CTC system itself was supplied and installed by the Union Switch and Signal Division of the Westinghouse Air- brake Company. The over-all system was envisioned and the basic plan drawn by the Paul Godley Company of Upper Montclair, N. J., communications consultants. As a loaded train comes down the hill from a 1500 foot altitude and runs the 90 miles to the port it passes return train loads of empties on passing tracks; work cars and maintenance crews are on sidings; these track movement controls come from the CTC board. The train reaches Puerto Ordaz, where the Caroni River joins the Orinoco, in about three hours. In Puerto Ordaz, the ore is crushed, stock-piled, and eventu- ally loaded by conveyor belt on an ore boat whose movements in the Orinoco channel are assisted and mapped by ship-to-shore radiotelephone. All changes up and down the 90 miles of track show in lights on the dispatcher's console. "Memory" devices permit the CTC system to store codes, since only one radio station at a time can transmit CTC codes. The stored codes, with their messages, are released on a CTC priority basis when the circuits are clear, in a matter of seconds, four seconds being the time needed to send a control or indication call. Switches are thrown by small trackside motors con- trolled by pulses sent by the microwave radio signal. The dispatcher initiates these pulses by merely pressing a button on his control machine. The pulses start out as d-c, are converted to tone and transmitted by micro- wave to a siding. They are reconverted into d-c at the receiving point where they operate relay equipment. The relays perform the desired predetermined functions. The CTC codes transmitted from the dispatcher's console are an uninterrupted 2,500-cps synchronizing tone and simultaneously, a 2,000 cps tone keyed for coding at approximately four pulses per second. Lights on console in Puerto Ordaz give dispatcher a complete picture of all movements on the system. The passing track radio stations are normally silent. However, to transmit a code, a passing track radio station is automatically turned on and keys the 2,500- cps synchronizing tone received from the dispatcher location, thus returning the tone to the dispatcher in the form of an indication code. There are no wire lines along the right-of-way, only the towers of the radio system and buildings for the generating plant and the small neat housing for the radio and rone equipment. The dispatcher maintains a log, showing the move- ments of all trains, their loads, crews and performance schedules. He has radio-telephone communication with all trains. He can talk to the engineer in his cab, the conductor in the caboose, and they can talk to him and to each other. This radio set-up also connects the port and the yard-master at the mine, and radio-equipped work trains and other mobile units. The overall Orinoco Mining Company telecommu- nication system is basically multi-channel and also pro- vides numerous communication services vital to mining operations, including a dispatcher-to-train radio system, four dial telephone channels, two teleprinter channels, a remote radio transmitter control and numerous tone dialing and signaling channels. Thus, four telephone channels operate between auto- matic exchanges connecting Puerto Ordaz and the mine, connecting hundreds of subscribers at each, and with one another, and over another Orinoco radio link with headquarters in Caracas. A teleprinter channel ex- changes vital printed telegrams between Orinoco Mining headquarters in the port, operational headquarters at the mine, and Caracas. This is part of an overall RCA engineered radio system which first helped Orinoco Mining penetrate the area, deepen the river channels and build cities, roads and docks, and which now connects Orinoco Mining's offices in Caracas, the mine, Puerto Ordaz, the town of Ciudad Piar, built at the foot of Cerro Bolivar, the ore ships in the river and the ore gathering system. Engineering on the system for the Union Switch & Signal Company was done by H. D. Etchison and W. P. Quintin, Jr. The radio project was directed for RCA International by D. H. Pain, with engineering by B. Sheffield, C. H. Brereton and R. M. Ball, Jr. Mr. Thomas says: "We are grateful to the Vene- zuelan Government for allocating all the frequencies necessary for rhe operation of our radio system. This cooperation is symbolic of the assistance we have re- ceived from Venezuelan authorities. It is matched by the wholehearted endeavour of all our Venezuelan per- sonnel, of which endeavour we are extremely proud." 8 ELECTRONIC AGE