November 1961 Radio-Electronics
[Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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News Briefs
A person using AT&T's new Picturephone can push buttons to control whether
he wants to be seen, see himself, see the other person, or nothing at all. Vidicon
lens is small circle at upper left of screen. Speaker is behind grill to right.
Control set uses no dial, but new "Touch-Tone" pushbutton calling system.
New York to California "Picturephone" Scores Hit at World's Fair
"See-as-you-talk" telephone was demonstrated publicly across the country for
the first time at the opening of the New York World's Fair. West Coast reporters
at Disneyland in southern California participated in a coast-to-coast press conference,
asking questions of Bell System executives in New York via "Picturephone" hookup.
The installation in the American Telephone & Telegraph pavilion at the fair
has been drawing great crowds. Soundproofed booths equipped with Picturephones have
been set up, allowing visitors to talk with each other and with a telephone operator
nearby. At occasional intervals throughout the day, a long-distance Picturephone
call is placed to a waiting participant at Disneyland.
Callers sit about 3 feet from the instrument's screen, housed in a compact desktop
set. Normal room illumination is sufficient for the tiny vidicon tube, next to the
receiving screen, to generate a good picture. The caller has his choice of a view
of himself, or of the party he's talking with or no picture at all.
Picture size is 4 3/8 x 5 3/4 inches, with a scanning rate of 275 lines per frame,
30 frames (60 fields) per second. The bandwidth required is about 500 kc (equivalent
to about 125 telephone circuits). Each Picturephone set has three pairs of wires
- one for the audio signal and two for the four-wire video transmission.
Vlf Signal Puzzle Near Solution
The strange behavior of very-low-frequency (vlf ) radio signals, which may be
received better in one direction than in the other when transmitted between two
points, may be near explanation, according to Douglass D. Crombie of the National
Bureau of Standards.
Radio signals do not travel equally well in opposite directions, and a number
of theories have been proposed to explain this anomaly. Crombie believes that the
cause may be magnetically caused changes in the radio waves' coefficients of reflection
or transmission at the ionosphere. In other words, the difference is due to the
earth's magnetic field. Greater signal loss on reflection in one direction is probably
due to increased transmission out through the ionosphere.
National Bureau of Standards Broadcast Changes
Transmitting clocks for stations WWV, WWVH, WWVB (and also Navy stations) were
retarded 100 milliseconds April 1 because of change in the speed of the earth's
rotation.
As of April 1 , WWVB and WWVL began broadcasting continuously from 1630 UT (Universal
Time) Wednesdays to 2230 Fridays. Saturday, Sunday and Monday they broadcast from
1630 to 2230 UT; they alternate on successive Tuesdays.
Geophysical alerts are broadcast on WWV and WWVH in International Morse code
(7 words per minute) during the first half of the 19th minute on WWV, and on WWVH
during the first half of the 49th minute past each hour:
GEO-MMMMM (Magnetic storm)
GEO-NNNNN (Magnetic quiet)
GEO-CCCCC (Cosmic ray event)
GEO-SSSSS (Solar activity)
GEO-QQQQQ (Solar quiet)
GEO-WWWWW (Stratospheric warning)
GEO-EEEEE (No geoalert issued)
By agreement with the Naval Observatory, WWV and WWVH started broadcasting on
May 1 daily corrections to the regular time signals to enable users to obtain a
very accurate value of UT2. During the last half of the 19th minute of each hour
on WWV and the last half of the 49th minute of each hour on WWVH, code signals will
be broadcast as follows: UT2 (space) AD or SU (space) three digits. UT2 is obtained
by adding or subtracting (as indicated) the number of milliseconds indicated by
the last 3 digits to the time as broadcast. The symbols will be revised on a daily
basis, the new value appearing for the first time during the hour after midnight
UT, and continuing for the following 24-hour period,
Trans-Moon Communications
Lunar communications over 600 miles or more with frequencies around 350 kc may
be possible, according to Prof. Newbern Smith of the University of Michigan.
Speaking at the US National Committee of the International Scientific Radio Union,
Professor Smith suggested that a "solar wind" consisting of electrons and protons
constantly streaming from the sun would create the equivalent of a lunar ionosphere.
This would refract or bend radio waves in the same way that our ionosphere bends
waves on the earth. Thus radio waves could be received at greater ranges over the
moon's surface than previously thought possible.
Range and quality would, of course, be sensitive to variations in the ionosphere,
which depends on solar activity, as well as the time of the lunar day. Communications
over distances even greater than 600 miles may be possible with elevated antennas,
Smith stated.
Satellite Discovers Huge Ray Zone
An 188-pound paddle-wheel satellite called Imp (for Interplanetary Monitoring
Platform), launched Nov. 26 from Cape Kennedy, has discovered an energetic radiation
zone that engulfs the Van Allen belt. It also confirmed that the earth is enveloped
in a turbulent shock wave of streams of energetic particles from the sun traveling
at speeds up to 300 miles a second, giving a new clue to the source of the particles
making up the Van Allen belt.
When the sunlit side of the earth collides with this shock wave (as close as
40,000 miles from the earth), it creates an ever-broadening wake that stretches
as far as the moon.
Sunspot Cycle Nearly Over
The present sunspot cycle No. 19 (the heavy solid curve on the chart) is approaching
its end. Current estimates are that cycle 19 will bottom out somewhere between November,
1964 and April, 1965. (The curve is dashed from November 1963 on since exact information
is not available beyond that date). The two previous sunspot cycles (17 and 18)
are shown for comparison. The peaks of cycles 18 and 19 were the highest measured
in the nearly 200 years of recorded sunspot history.
Chart courtesy of the BBC.
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