- News Home
6 March 2014 1:04 pm ,
Vol. 343 ,
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
- 6 March 2014 1:04 pm , Vol. 343 , #6175
- About Us
18 December 1997 8:00 pm
The father of FM radio was born on this day in 1890. In the 1920s, radio broadcasting used only amplitude modulation (AM), in which a signal is transmitted by variations in the amplitude of a radio wave. Such signals were susceptible to the crackle of static from storms and electrical disturbances. In 1933, electronics engineer Edwin Armstrong introduced radio broadcasting by frequency modulation (FM), in which the signal is transmitted by variations in the frequency of the radio wave over a wide waveband. This method, which now dominates radio, television, microwave, and satellite transmissions, is unaffected by static, although it is limited to line-of-sight distances. Armstrong is also known for his invention of the superheterodyne receiving circuit, which was used during World War I to detect enemy aircraft by the radio waves given off by the ignition systems of their engines.
[Source: Roy Porter, Ed. The Biographical Dictionary of Scientists, Second Edition. Oxford University Press. 1994.]