Anti-streptolysin O (ASO) is an antibody often found in the blood of people who have suffered a streptococcus infection. A blood test, known as the anti-streptolysin O titre, is sometimes used to test for the presence of this antibody in the blood. This test is considered useful because certain health conditions, such as rheumatic fever, usually only occur in people who have recently suffered or are suffering a streptococcus infection.
On December 26, 1933, he was awarded four patents for FM radio (The other two were applied for in 1927 and 1930, but weren't for wide-band). He discovered in early 1934 that his invention was almost free of static. Armstrong took a few more years to give FM high fidelity, but by 1938 or 1939 he had improved FM to the point that it was our FM radio, minus the stereo sound.
Ham Radio History In 1873, James Clerk Maxwell presented his theory of the electromagnetic field. In 1901 Guglielmo Marconi communicated across the Atlantic with a radio device using high power and giant antennas. To curb interference, Congress approved the Radio Act of 1912, which required amateurs to be licensed and restricted to the single wavelength of 200 meters.