Measures for Progress: A History of the National Bureau of Standards

474 THE NEW WORLD OF SCIENCE (1946-5i)
and commercial radio, as the central agency of the Nation for basic research
in the propagation of radio waves.124
Besides continuing operation of the worldwide chain of stations—the
total number was 58, of which 14 were directly operated or supported by the
Bureau—to provide prediction services for long-distance radio, CRPL took
over the research functions of the radio section of the Bureau's electrical
division. It at once undertook extension of the research in lower frequencies
into the ultrahigh frequency and microwave region (3000 megacycles or
more) for the new fields of television, of frequency modulation (FM) broad-
casting, and military and commercial radar.
Severely limiting the range and minimum usable signals in FM broad.
casting, television, and other very-high-frequency services, the Bureau found,
was the noise associated with cosmic and solar radio waves reaching earth
from outer space. To study these phenomena, the Bureau instituted a pro.
gram in radio astronomy, setting up at Boulder two solar radiometers with
mirrors 25 feet in diameter, operating at different frequencies, to track the
sun and observe its outbursts of radio energy.125
While outer space phenomena produced measurable limitations on
very:high.frequency transmission, the major influences on propagation at
microwave frequencies proved to 'be nearer to earth. Studies in tropospheric
meteorology and terrain geometry—that is, the effects of rain and trees and
hills—first begun several decades earlier for ordinary radio transmission,
were resumed in order to learn the causes of attenuation of very short micro-
waves, particularly those used in radio relay operations.126 Both the radio
astronomy program and that on the troposphere became long-range projects.
An innovation in the radio services of the Bureau, begun on October 3,
1945, shortly before setting up CRPL, was the shortwave broadcast of stand-
ard time signals each 5 minutes around the clock. It augmented the standard
radio frequencies, standard time intervals or pulses, standard audio frequen-
Hearings * * 1948 (Mar. 12, 1947), p. 339. Establishment of CRPL was authorized
in letter, Secretary of Commerce Wallace to Secretary of the Treasury, Jan. 9, 1946 (copy
in NBS Historical File), and activated as a division of the Bureau by memo, Director,
for Division and Section Chiefs, NBS, Apr. 19, 194.6 ("General Correspondence Files
of the Director, 1945—1955").
NBS Annual Report 1948, p. 247. The new branch of science, radio astronomy, had
its beginnings in 1932 when Karl G. Jansky of the Bell Telephone Laboratories described
the reception of extraterrestrial radio waves and from their diurnal variation in direction
tentatively identified their source in the Milky Way. See Proc. IRE, 20, 1920 (1932)
Nature, 132, 66 (1933). Grote Reber, both before and after he came to the Bureau
in the 1940's, and the Bureau's chief of radio research, Dellinger, were to extend these
observations. See F. T. Haddock, "Introduction to radio astronomy," Proc. IRE, 46,
3 (1958).
NBS Annual Report 1949, p. 71.