STATIC PROBLEM OVERCOME

Press, Volume LXXI, Issue 21647, 4 December 1935, Page 15

STATIC PROBLEM OVERCOME

NEW BOON FOR RADIO LISTENERS AMERICAN DEMONSTRATION NEW YORK, November 5. A "static-less" radio system invented by Major Edwin H. Armstrong, Professor of Electrical Engineering at Columbia University, was demonstrated for the.first time before the Institute of Radio Engineers here. Major Armstrong contends that his system, if applied to broadcasting, especially on shortwave bands, would usher in a new era in reception and make it possible to send and receive as many as four programmes simultaneously on one wave-length. Describing a series of tests carried on in the New York vicinity for more than a year over the shortwave station on top of the Empire State building and a receiver of the "static-less" variety at Haddonfield, 85 miles away, Major Armstrong introduced recordings made during a thunderstorm. Programmes broadcast over regular local long-wave stations were compared for clarity with the same presentations wired to the Empire State transmitter and sent to Haddonfield over the "static-less" receiving system. The recordings revealed that the Armstrong system was' virtually free of interference caused by lightning, while the programmes of much more powerful stations were punctuated by the noise induced by the flashes. Then Major Armstrong described and demonstrated teats made between the Empire . State sending outfit and a New. York broadcaster of about equal power, with results highly favourable to his system. No noise was heard when his "static-less" system was in circuit, while a great deal of noise was present without it to still the crashes of lightning. A test was then made by tuning in an amateur station in Yonkers of 100 watts power, operating on two and a half meters. The waves arrived at an aerial on the Engineering Auditorium building, 33 West Thirty-ninth street, where the demonstration was held before several hundred engineers. Amid the electrical noises that infest the downtown area and make any kind of radio reception precarious, the new system brought in clear signals. Records of the voice of Caruso and several recordings of' Sousa's music were amplified over a battery of loud-speakers with only a slight hiss as the background. The Yonkers amateur station used the new Armstrong system, called "frequency modulation." Ordinary broadcasting utilises what is known as "amplitude modulation."

/ Engineers in the audience expressed wonder at the ability of the apparatus to exclude noise and pass the programme unimpaired to the. loud-speaker. Amplifying his brief statements during the test, Major Armstrong contended that "frequency modulation eliminates vacuum tube noises and distortion in reception due to fadihg." The whole range of musical vibrations, he said, "can be transmitted because the limitation on higher tonal frequencies existing in present-day broadcasting is removed" by this device. " . , In addition, Major Armstrong said, the new system was especially adaptable to television relaying where interference must be avoided.

Child films have become enormously popular 'in Russia, according to Mr Sidney Bernstein, the English exhibitor, who recently returned from a tour of the U.S.S.R.