Radio age (Jan-Dec 1924)

26 RADIO AGE for May, 1924 The Magazine of the Hour Measuring Time and Distance by Radio SOME well intormed radio engineers and many blase radio fans were electrified and even astounded to observe the radio time and speed experiments of Captain R. H. Ranger of the Radio Corporation, conducted at the Cosmos Club in Washington before a section of the Association of Electrical Engineers. He not only transmitted a radio message 4,250 miles to Warsaw, Poland, and got a reply in approximately three minutes, but he measured the time required for a single radio impulse to make the round trip as .046 second. The latter experiment was to show that contrary to a popular conception, radio is not instantaneous. "The fact that a radio impulse traveling over a given distance negotiates this space in a definite and fixed time may set a new standard against which time and distance may be measured, giving a degree of accuracy and reliability surpassing even the accepted methods of astronomical observations," Captain Ranger declared. "What does he mean?" some of the uninitiated immediately inquired. He meant that since it takes appreciable and measurable time for a' radio signal, a dot in this instance, to travel a given distance, we have a new standard measuring instrument which will remain the same for centuries, and, with continued use, our ability to measure even small lapses of time will increase. Practical applications include aids to the mariner, until recently dependent upon dead reckoning when the sun was invisible and no radio beacons ware available. "Radio," Captain Ranger said, "will be the answer to civilization's demand for greater accuracy." Already this system makes it possible to check the accuracy of automatic relays and in the future we may expect more useful applications — for example, to check time differences between two distant points. With a globeencircling chain of powerful stations, the world time could be carefully calibrated. The radio "dot" can eventually be made to act as a very accurate check on longitude determinations. By way of exposition, Captain Ranger said: "Suppose clocks at Warsaw and New York are geared accurately to the sun's time at each locality. Then transmit Warsaw's sun time to New York. The difference in the two clocks, in New York, gives the portion of the day or revolution of the world between the two, which is the difference in the longitudes." With the present advances in radio, the least accurate part of such measurements comes in the solar observations, but in spite of this, he said, accuracies below fifteen feet in the 4,250 miles covered are in order. When the round-the-world radio "robin" has checked the speed of radio waves to the final degree, radio alone will give the actual distances between any two points, according to this engineer. The actual experiments at the Cosmos Club were conducted by coupling the transmitting key in Washington to the Kadel & Herbert Futo THREE-STORY SUPER-HETERODYNE Mrs. Henry Brinkman, Pelham, N. Y., tuning in with the receiver by Mr. Brinkman. Note the non-capacitant loop aerial which, by bunching wires, improves selectivity and eliminates capacity effect in tuning. Ten turns of wire, tapped at each turn, can be used collectively or separately. Radio Corporation's New Brunswick transmission station by a land line, thence by radio to Warsaw, a distance of 4,250 miles. The return circuit was by land wire from the Polish receiving station thirty-five miles to the transmitter and back via radio to the River Head, L. I., receiving station; from there to Washington thorugh the radio central by a land line. A 14-tube receiving set in the club was tuned in on the New Brunswick transmitter, but the signals picked up were shown visibly through the pulsations of a small electric light instead of on a sounder. By this means, code experts could read the transmissions emanating from New Brunswick as controlled by the senders' key in the club, and observe the messages sent Poland, en route as it were. Once the circuit was set up messages and replies were exchanged from Washington to Poland within three minutes, and later the single dot signals were calculated, with certain corrections, to have made a round trip of 8,500 miles in .046 of a second. This indicated the actual speed of radio as roughly 185,000 miles a second, due to some errors not possible to correct in the makeshift apparatus used. Another experiment established the possibility of using a radio system to determine the location of ships at sea, serving the purpose of a radio log. If a ship sa.ls in a straight line between two ports, it will be possible and practical with proper recording apparatus to know just how far a ship had sailed in radio waves. With refinements, this would actually be a "radio speedometer," it was explained. We may come to speak of a ship traveling at "twelve wave lengths an hour" instead of twelve knots. A radio instrument in the pilot house will give the navigator his speed at a glance, as well as his distance from port. Captain Ranger also covered the uses of radio in polar flights and in establishing the position of air and sea craft both aboard the vessels and at the land compass stations taking the observations, thus preventing any "faking" of positions in the future. Scientific expeditions, he said, could be furnished with accurate time, essential in navigation, by radio, or be actually guided by radio from base stations. Concerning the possibility of communicating with Mars, the captain was skeptical, due to the fact that the earth's envelope acts as an impervious electric mirror and reflects radio waves to the earth. This "heavyside" layer, he explained, would also tend to deflect any signals emanating from Mars.