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March 1967 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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In 1967 when this set of
News Briefs was published in Radio-Electronics magazine, the use of
semiconductors in laser light applications was the domain of
government, corporate, and university research laboratories. The device only
modulated the beam. It did not generate the beam, although as seen below
infrared laser diodes were already in the works. Also wowing the readership was
a pinhead-size gallium arsenide (GaAs) transmitter which could generate
frequency modulated (FM) signals in the 60 MHz to 2.5 GHz range. The "highest
ever" starting salary for engineering students in that year was a whopping
$166/week, or $8,632/year. That is the equivalent of
$80,674 in 2024 money. By comparison, $16/hour fast food workers in
California are
pulling in $33,280/year, and qualify for many welfare benefits and healthcare. A
really interesting item is how a group of British high school radio enthusiasts
routinely tracked Russian satellite orbits to reverse engineer the point of
launch, and on occasion discovered new ground bases, like the
Plesetsk Cosmodrome in
Mirny.
New Briefs:
11/1957
| 8/1958 |
11/1959 |
2/1960 |
4/1960 |
8/1960 |
3/1961 |
5/1961 |
6/1961 |
12/1961 |
3/1963 |
4/1963 |
8/1963 |
9/1963 |
8/1964 |
12/1964 |
1/1967 |
3/1967 |
4/1967 |
9/1967 |
4/1968
News Briefs
 Broadband Light Modulators
The modulation of a laser beam, for transmitting information, has required much
power and hasn't been possible with much bandwidth in the past. Now, Bell Telephone
Laboratories scientists have discovered three ways to impress broadband signals
on laser beams, using modulating powers of less than 1 watt.
The gallium-phosphide diode is one system (see sketch). Reverse bias is applied
to the diode, and an incoming light wave is polarized and focused on the diode's
pn junction region. The two polarization components of the light wave then travel
at different velocities along the plane of the pn junction. They emerge from the
junction out of phase with each other. This is equivalent to phase modulation. Finally,
the phase-modulated components are passed through an output polarizer, where PM
is converted to AM.
The gallium-phosphide diode can modulate light because of the linear electro-optic
effect-which takes place in the diode pn junction when a reverse bias is applied.
The semiconductor requires only 1.5 mW of power per MHz of modulation bandwidth.
The second device is a lithium tantalate electro-optic modulator. It uses a coded
sequence of high-speed electrical pulses or digits to modulate an equally fast,
uncoded train of light pulses from a helium-neon laser. The lithium tantalate modulator
is most useful in pulse-code modulation of digital information; it can handle up
to 896 million bits per second.
The third device is an infrared modulator, consisting of a thin rod of gallium-doped
yttrium iron garnet. Infrared light waves traveling through the crystal are continuously
modulated when the direction of the crystal's internal magnetic field is varied.
With power of only 0.1 watt, this device has a bandwidth of 200 MHz.
 Microwave Microtransmitter
Electronics is getting to sound like science fiction - remember "The Incredible
Shrinking Man"? Latest near-disappearance: an FM transmitter (range 60 MHz-2.5 GHz)
slightly larger than a pinhead.
The device-shown in the photo dwarfed by its mounting holder - is made of gallium
arsenide. The application of relatively high voltage to the semiconductor, causes
Gunn effect and microwave emission. Field-effect principle is then used to modulate
the microwave carrier. The new device has three terminals, is effectively a junction
diode with a modulation gate added.
The tiny transmitter was developed by a team of RCA scientists, who envision
hand-held microwave transmitters that would open up a new range of personal-communication
possibilities.
Engineers Still Earn Most
Students who are graduated from engineering colleges this year will be paid an
average starting salary of $166 per week. That's the highest beginning wage ever
paid to a new diploma holder, and tops all other graduates in business and industry.
These estimates are compiled annually in a study of industry hiring practices by
Frank S. Endicott, director of placement at Northwestern University. Since 1947
- when Endicott's surveys started - engineering graduates have consistently received
top starting salaries.
 Laser Brake for Cars
A new combination of radar and laser techniques could decrease traffic accidents.
A solid-state injection laser (see photo), in this case a semiconductor that emits
coherent light, is being considered as the heart of a new form of automobile collision-avoidance
system. Infrared light from the laser would be bounced off the car ahead - as in
a radar system - and would warn if a collision was impending. Warning would be given
with lights or audible signals; if the driver failed to take corrective action,
brakes would be applied automatically.
The laser device also has possibilities as fog penetrator, burglar alarm, and
private communications system. As the solid-state laser can be modulated, it could
be used to aim a narrow beam of infrared "signals" at a receiver. intercepting the
message would be nearly impossible without knowing which way the transmitter was
aimed.
Devices available from the developer (RCA) include a 50-watt injection-laser
diode array about the size of a pencil eraser, a 2-watt unit smaller than a kernel
of corn, and IR light emitter close to the size of the bead of a pin.
Teenage Students Discover Soviet Missile Base
As a man-made satellite moves across the sky, its radio transmissions change
pitch slightly with respect to a fixed receiving station - due to Doppler effect.
Using this principle, a group of English school students tracked Russian space launches.
Working backward from the orbit records they accumulated, and using a computer,
they pinpointed the location of a new missile base unknown to the West until now.
The students have a surplus WW II military radio, a 40-foot antenna, and an ordinary
globe of the world. Since 1962, the group of 100 boys and girls - aged 15 to 18
- have made 1,700 radio observations, recording the orbits of 75 USSR satellites.
In some cases, they have recorded a missile launch before the Soviets have announced
it. All data gathered by the students is sent to the British space agency.
It has been known that the Russians have been using space-launch bases at Kapustin
Yar and Tyuratam for several years. Site found by the British students is at Plesetsk,
400 miles north of Moscow and the USSR's first far-north space base.
Posted March 7, 2024
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