February 1958 Radio-Electronics
of Contents]These articles are scanned and OCRed from old editions of the Radio & Television News magazine.
Here is a list of the Radio-Electronics articles I have already
posted. All copyrights (if any) are hereby acknowledged.
International Geophysical Year (IGY) began on July 1 of 1957 and ran
through December 31 of 1958 (actually IGYaaH - IG year-and-a-half).
It was the dawn of space / high altitude flight and there was a great
need to learn as much as possible about the physics of the upper atmosphere
and the void of space. The USSR successfully flew their first three
satellites and the U.S. was scrambling to get
into orbit (finally on August 12, 1960, after the
end of IGY). The Cold War was at its peak (Bay
incident was just a few years away), and the science world
was looking for a way to provide a unifying tie between the planet's
countries. "During this time, more than 5,000 scientists and engineers
of more than 60 nations are conducting intensive investigation and study
of the earth, the atmosphere and the sun. Into these 18 months are crammed
30 or 40 ordinary years of research as science attempts to get a better
picture of our geophysical environment," per author Jordan McQuay.
James Van Allen
, one of the IGY's progenitors, discovered the eponymous
radiation belt encompassing the Earth during that time.
See all available
vintage Radio-Electronics articles
Part I: Electronics contributes to the success of the International
By Jordan McQuay
Fig. 1 - This typical IGY observing station (Fritz Peak, Colorado)
houses a photoelectric photometer and other optical equipment.
One of the most significant scientific undertakings in the history of
mankind is the IGY or International Geophysical Year. It began last
July and continues until next December - a period of 18 months.
During this time, more than 5,000 scientists and engineers of more
than 60 nations are conducting intensive investigation and study of
the earth, the atmosphere and the sun. Into these 18 months are crammed
30 or 40 ordinary years of research as science attempts to get a better
picture of our geophysical environment.
At more than 1,000 field
stations, scientists and engineers are exploring every major land and
sea area. They are studying the earth's core and crust, and the atmosphere
around our globe. And throughout these many and diversified studies
and explorations, electronics plays an important role.
the science of electronics can detect, observe and measure many of the
phenomena associated with the earth and the sun as they move through
space. So great is this role of electronics that much of the success
of the IGY depends directly on its use.
The IGY program covers
a dozen major areas of scientific activity. These include meteorology,
aurora and airglow, geomagnetism, cosmic rays, glaciology, gravity,
longitude and latitude determinations, oceanography, seismology, solar
activity, and rocket and satellite studies of the upper atmosphere.
Although the earth-satellite program is perhaps the most popularized,
this is only one of the areas of scientific activity during the IGY.
In most of these areas, electronics is utilized in some way
to detect, collect, measure and record data concerning the earth and
its atmosphere. Through electronics, these data provide not only new
basic knowledge but also applications in many fields of human interest
- from transpolar air travel to better radio communications, air navigation
and weather predictions.
This, in essence, is the purpose of
the IGY. And electronics is an important means of making many of these
Fig. 2 - A rawin set - a radiosonde and directional radio receivers
- used to collect meteorological data.
Fig. 3 - An Aerobee-Hi rocket a few moments after launching.
US Army Photographs
With every advance of civilization,
knowledge of the weather has grown more and more necessary. To cope
with change in the weather, reliable predictions - particularly long-range
predictions - are needed.
One difficulty in predicting weather
has been the lack of adequate data from the Arctic and Antarctic regions,
which influence the world's weather.
During the IGY two drifting
and several fixed ground stations in the Arctic and more than 50 ground
stations in the Antarctic have been established to collect data influencing
the weather. For the first time in history, adequate meteorological
coverage of the Southern Hemisphere is being provided.
various ice-bound sites, balloon-borne weather instruments are sent
aloft and radio back information on air pressure, temperature, humidity,
precipitation and prevailing winds. Radiosonde and rawinsonde equipment
provide this data at heights up to about 100,000 feet. At each site,
information is collected and then transmitted-via radio circuits - to
central points for analysis and recording.
In addition to the
Arctic and Antarctic stations, there are more than a hundred other weather-observing
stations in more temperate regions, particularly in the Western Hemisphere
Stations are not identically equipped. A variety of
electronic and other measuring instruments is used at many sites.
Observations of solar radiation are made with pyrheliometers
and recorders. Infrared measurements are made with infrared absorption-cell
hygrometers. Sky brightness and sunshine duration are recorded with
photometric switches. Atmospheric ozone is measured with Dobson spectrophotometers.
Other ground-based devices detect and measure radiated sun heat, snowfall,
wind and temperature. At selected sites throughout the world, the sun
is photographed every 30 seconds. Radiosondes at Work
Important to the study of meteorology at the various
IGY sites is a continuous knowledge of wind direction and velocity,
air temperature and humidity and other data from lower regions of the
Instruments for recording these data are known
as radiosondes and are carried aloft by balloons about 6 or 7 feet in
diameter. Data collected by a radiosonde are broadcast to ground-based
radio receivers for further analysis. Each radiosonde weighs about 2
pounds and is about the size of a hand telephone. Besides being a compact
radio transmitter, it carries a thermometer, a hygrometer for measuring
air humidity, a barometer and a miniature battery for a power source.
After release, the balloon rises while the miniature transmitter
flashes vital statistics to ground-based receiving stations. Each receiver
automatically tracks the radiosonde and records the drift of the balloon
as well as data transmitted by the radiosonde as it moves through space.
A combination of a radiosonde and several ground-based receivers
is known as a rawin (Fig. 2) or rawinsonde. The system operates up to
altitudes of about 100,000 feet, when the balloon bursts. The radiosonde
is then eased down by parachute to forestall possible injury to persons
or damage to property. Most balloons and airborne gear are lost. But
they have fulfilled their mission in meteorology for the IGY.
Data collected by the rawin are sent by radio or wire lines to central
control points, where they are recorded and analyzed further - usually
by electronic data-processing machines. Data are stored on tapes or
punched on cards and ultimately used for regional weather predictions.
Although these data - collected at altitudes up to 100,000 feet
- are important, for long-range weather prediction there is a need for
similar data collected from much higher altitudes. Collection of such
data is possible only by use of special rockets. The
Meteorological and other data are
being collected from the upper atmosphere by four kinds of rockets:
The Aerobee-Hi is a liquid-fuel rocket. In a 6-cubic-foot space,
it carries a payload of 150 pounds of scientific equipment to an altitude
of about 170 miles. It is 23 feet long and about 15 inches in diameter.
The Nike-Cajun uses a solid propellant and carries a 40-pound
payload to an altitude of more than 100 miles.
also uses a solid propellant to carry a 40-pound payload to an altitude
of about 75 miles. Both rockets use the Nike as a booster.
Rockoon is a Deacon rocket carried to about 80,000 feet by a Skyhook
balloon before the rocket is actually fired. It carries a 40-pound payload
to an altitude of more than 60 miles.
Of the dozen or so rockets
fired to date, most were the Aerobee-Hi type. The majority of them were
fired in the Arctic region. See Fig. 3.
in meteorology is the measurement of upper-air temperatures and the
collection of air samples to determine their composition. This can be
done with rockets, which also provide a way of determining wind speed
and direction at heights never before possible.
increases with increasing altitude because the ozone absorbs ultra-violet
radiation. Thus, great out-bursts of ultra-violet radiation caused by
a solar flare may result in temperature increases which are reflected
at the earth's surface in marked weather changes. With these data, collected
by the rocket and relayed to ground stations, much more accurate weather
forecasting is possible.
Two methods of measuring temperatures
at high altitudes with rockets have been used successfully during the
IGY. One system is based on the principle that the speed of sound is
influenced by temperature. The speed of sound is measured through a
series of small detonations that occur just outside the rocket housing
at closely timed intervals during flight. Microphones on the ground
detect each burst, and the exact time of arrival is recorded by electronic
data-processing equipment. At the same time, radar and optical tracking
equipment determine the exact location of each detonation in space as
the rocket ascends. The position and time of arrival of each of the
successive detonations indicate the speed of sound through the layer
bounded by each burst. Thus, the mean temperature for each stratum of
atmosphere can be determined electronically.
of temperature measurement requires knowledge of the angle made by the
shock waves off the nose of the rocket during flight. These waves are
detected by pressure-sensitive probes mounted on the outside of the
rocket housing and, after amplification, are recorded on a magnetic
tape inside the rocket. The data are also telemetered to a receiving
station on the ground. From a knowledge of the fixed angle of the probes
plus the location and speed of the rocket (determined by ground-based
radar), the air temperature along the upward path of the rocket can
be determined electronically.
Air is sampled at high altitudes
by sending special vacuum bottles aloft within a rocket. At predetermined
altitudes, the containers are opened, and then closed and sealed by
electromechanical devices. Rockets are also equipped with instruments
to detect and record other phenomena under study during the IGY.
Fig. 4 - Miniature radar-beacon transceiver (right) and its
power supply for rockets used to explore the upper atmosphere.
US Army Photographs
Preliminary results during the IGY indicate that up to about 40 miles
altitude, atmospheric gasses are completely mixed. Above that level,
the amount of argon (a heavy gas) decreases and the amount of helium
(a light gas) increases.
Rockets in flight are located and tracked
by ground-based radar stations and sound-ranging stations. Each rocket
carries a small transponder beacon (Fig. 4) which transmits a return
signal to IGY stations on the ground.
Radar tracking also provides
a measure of safety. If the rocket veers off course during its powered
ascent, such a deviation is noted quickly by the ground-based radar
equipment. If the behavior of the rocket becomes dangerously erratic,
a change of signal is transmitted from the ground to the radio receiver
in the rocket. This, in turn, breaks the fuel line and terminates the
To protect the delicate electronic instruments in the
rocket from landing shock, they are carefully packed and braced. Some
rockets are constructed so the nose and tail assemblies are blown apart
during downward flight. A nylon parachute brings down the nose section
that houses the electronic measuring and recording equipment.
Most rockets carry out several different IGY experiments during
a single flight. Thus the total number of flights is not indicative
of the true importance of this phase of the IGY program.
several ground stations used to track and control the rocket are connected
via communications circuits using conventional radio or wire facilities.
Collected data are evaluated and stored at central locations by electronic
processing and storing equipment. Solar Activity
Investigation of the upper atmosphere by radiosondes
and rockets is supplemented by other IGY studies, all intended to enhance
our knowledge of this region that surrounds us.
- extending above 100,000 feet and thinning out into nothingness hundreds
of miles above the earth - plays a dominant role in our lives. It provides
a shield against lethal radiation from the sun and from dangerous cosmic
radiation. It maintains the heat balance of the earth, so surface temperatures
are suitable for life. And it affects our lives in many other ways.
Under study during the IGY are events and conditions that take
place more than 50 miles above the earth's surface. The sun dominates
most of these events, which include aurora, airglow, cosmic rays, geomagnetism
and other solar activities.
Any unusual solar radiation - either
in intensity or kind - influences the upper atmosphere. This, in turn,
affects radio communication, navigational systems and other electronic
activities dependent to some degree on the transmission and reception
of electromagnetic waves through space.
Solar activity is generally
measured in terms of an 11-year sunspot cycle. Sunspot bursts or other
active phenomena on the surface of the sun have lifetimes varying from
a few days to a few months, invariably according to the 11-year time
scale. Brief spurts of activity occur in some solar regions and may
last from a few minutes to a few days.
Variations in any of
these solar activities frequently determine weather conditions on earth.
For this reason, the IGY program was purposely timed to coincide with
the peak of sunspot activity so that geophysical events in the upper
atmosphere would be at their maximum.
To observe these solar
phenomena, a network of more than 400 ground-based stations has been
established around the world. The stations are spaced to allow a continuous
optical and electronic watch of the surface of the sun and the upper
atmosphere. Events occurring in the visible as well as radio frequencies
are measured and recorded. These include the number and size of sunspots,
solar flares and solar (radio-frequency) noise - all correlated with
time. At these and additional stations in the Arctic and Antarctic,
aurora and airglow are also observed and recorded.
dancing light is the visible evidence of the bombardment of the earth's
atmosphere by charged particles from the sun. It is a luminous trace,
usually occurring near the north and south geomagnetic poles of the
Airglow is a faint glow of light, somewhat like aurora,
caused by a chemical reaction in the upper atmosphere of Arctic and
Antarctic regions. Both aurora and airglow interfere with radio communications.
At IGY stations in polar regions, aurora and airglow are observed
and recorded with radiosonde equipment associated with photoelectric
photometers, scanning spectrometers and high-dispersion spectrographs.
Photographs of aurora and airglow are taken at regular intervals
with specially built automatic-sequence all-sky cameras - which cover
the sky from horizon to horizon. Each instrument incorporates a 16-mm
motion-picture camera which photographs the entire sky as seen in a
convex mirror. Exposures are taken about once every 5 minutes.
Data on auroral forms and intensities are classified and recorded
electronically in terms of sky location and time, reduced to punched-card
form and filed for future reference. This work is done by conventional
electronic data-processing machines.
During periods of marked
solar activity, rockets are also used to obtain data for study and record.
In airglow experiments, photon counters are encased in the rocket. These
counters are used at various wavelengths in the visible spectrum with
their output coupled to amplifiers containing photo-multiplier tubes
and filters. Auroral articles - almost infinitesimal dust - are collected
and measured with Geiger counters, proportional and scintillation counters,
ionization chambers and related equipment mounted within the rocket.
All data collected by rockets are recorded and then telemetered to ground-based
When scientists cannot observe an aurora
visually or photographically, the course of the aurora is followed with
radar equipment. The path of an aurora can also be studied by means
of radio and radio astronomy. The pattern of auroral interference with
ordinary radio transmissions on the earth and with the arrival on earth
of radio-frequency emissions from the sun and other planets provides
valuable data for predicting radio propagation.
are other solar phenomena. Although their origin is a mystery, their
presence can be detected and their characteristics examined. These are
essentially positively charged particles that bombard the earth from
all directions. Excessive bursts of cosmic rays frequently coincide
with other ionospheric disturbances and are so severe that they not
only interfere with but sometimes prevent radio communication.
At the many IGY observation stations around the world, cosmic rays
are studied with other solar activities. Used for this purpose are cloud
chambers, ionization chambers, window Geiger counters, electronic impulse
counters and other special instruments to detect and measure cosmic
rays. Information is recorded in terms of time for later comparison
with other solar disturbances and effects.
Raw data are exchanged
between IGY stations via radio communication - usually using high-speed
teletype-writers. At key central stations, data from all observing points
are correlated and recorded by electronic data-processing equipment.
A region of rarefied
ionized gases - from 50 to 250 miles above the earth - is known as the
ionosphere. It is electrically active because of ultra-violet radiation
from the sun, and reflects radio waves from earth much as a mirror reflects
light. For this reason, radio communication is entirely dependent on
the ionosphere for long-distance transmission.
The region is
far from stable. It is composed of layers of ionization which change
radically with time of day, with season, and even from year to year.
Its radio-wave reflecting characteristics also vary with prominent solar
activities. A flare on the sun is frequently followed by an ionospheric
disturbance that blacks out all long-distance radio communication. Active
sunspots and violent auroral displays also affect the ionosphere and
result in major paralyses of long-distance communication.
detailed study of the ionosphere and its many and varied characteristics,
some of th e mysteries of this ionized region may be deduced during
the IGY. Observing stations are endeavoring to collect data on the characteristics
of all layers or part of the ionosphere. Of particular significance
are data on variations of charge density with altitude.
are measured vertically and obliquely from each observing station at
regular intervals, using automatic multifrequency ionospheric recorders.
This equipment normally sweeps from 1 through 25 mc in a period of about
20 seconds, and this sweep is repeated about every 20 minutes. Radar
data are recorded on 35-mm film, which is processed and scaled daily
for significant ionospheric characteristics.
Fig. 5 - Antenna array of an IGY observing station (Boulder,
Colo.) used to study effects of the ionosphere on radio-wave
National Bureau of Standards Photo
Rockets are also used to determine ionospheric charge densities in three
ways: In the first, the delay time of an electromagnetic pulse sent
from the ground station to the rocket is measured. In the second, two
harmonically related signals are transmitted from the rocket in the
ionosphere; with a known phase shift, the index of refraction in the
vicinity of the rocket shell is a measure of the charge density. In
the third, the charge density is determined from the effect of the ionosphere
on DOVAP (Doppler, velocity and position) signals. Data are either recorded
by electronic equipment within the rocket or raw information is telemetered
to ground-based receiving equipment where it is recorded and analyzed.
Nearly a hundred observing stations have been established at
points around the world specifically for the purpose of measuring the
position and density of layers of the ionosphere. Much of this work,
particularly in the. Antarctic, has never before been attempted.
Data of this type from all ionospheric and other observing stations
are collected and assembled to obtain a worldwide pattern for prediction
purposes. See Fig. 5.
Other investigation of the ionoshere include
the use of solar spectrographs, encased in rockets, to determine the
distribution of ozone in the upper atmosphere. A radio-frequency mass
spectrometer is used to measure the chemical and ion composition of
the ionosphere. These plus wind and other measurement are either recorded
electronically within the rocket or are transmitted to the ground observing
stations for study and record.
Another field of intensive study
is the recording and measurement of atmospheric radio noises. At principal
stations of the global IGY network, noise is recorded continuously,
24 hours a day, on magnetic tape, with appropriate time references for
comparison with other meteorological data.
whistling atmospheric noise is the subject of a special study during
the IGY in an effort to identify the origin and define the characteristics
of this kind of radio interference.
Other IGY studies relating
to the ionosphere include investigation of oblique-incidence forward
scatter, sweep-frequency back scatter, absorption and other phenomena
relating to the propagation of radio waves.
Any unusual solar
or ionospheric activity in one region of the world is communicated to
other IGY stations by a global radio network. This allows more intense
study of the same phenomenon and its effects at various sites throughout
Next month - a look at the earth satellite and its
place in the International-Geophysical Year.
To Be Continued...
Posted February 27, 2014