|
September 1945 Radio-Craft
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
|
Two items particularly caught
my eye in this group of news tidbits from a 1945 edition of Radio-Craft
magazine. The first was the drawing of a scheme for mobile-to-mobile as well as
fixed-station-to-mobile radiophone service - cellular telephones! A frequency band
of 152-162 MHz had been allocated for "urban mobile service." Towers and base
transceiver stations (BTS) would be erected along the most commonly traveled routes
to ensure contiguous coverage. Two years later, in 1947, Bell Systems initiated
its Mobile Telephone Service (MTS) based largely on the principle
presented here. The second thing that interested me was a plan by Raytheon to institute
a microwave relay system to facilitate intercontinental phone traffic. Bidirectional
service operated on 105 MHz and 107 MHz. Also in the news was rescinding
of the prohibition against production of non-war-related electronics for home use,
government-funded television research by the Ruskies, and FM radio station frequency
allocations.
Radio-Electronics Monthly Review
The automobile traveller would remain in touch with his home,
even across the continent.
Items Interesting to the
Technician
Two-Way radiophone between moving automobiles and other motor
vehicles and subscribers to the regular land telephone will be in common use in
the near future, according to plans announced last month by the American Telephone
and Telegraph Co. This will mean that telephones on automobiles, trucks or other
mobile units such as boats and barges will be connected with the general telephone
system, so that a subscriber to the general two-way mobile service can talk from
an equipped vehicle to anyone of the millions of telephones served directly by or
connected with the Bell companies. Likewise, the occupant of an equipped vehicle
can be called from anyone of the millions of telephones.
Calls to and from motor vehicles will be handled by special operators. The conversation
will travel part of the way by telephone wire and part of the way by radio. If a
caller at his desk wants to talk to the occupant of a certain automobile, he first
dials or asks for the vehicular operator. He gives her the call number or designation
of the vehicle. She sends out a signal on the proper radio channel by dialing the
code number assigned to that particular vehicle. An audible or visual signal indicates
to the car occupant that he is wanted. He picks up his dashboard telephone and the
conversation starts.
The operator of a mobile unit can originate calls merely by picking up his telephone
and pushing the "talk" button. This signals the vehicular operator and she "comes
in on the line." He gives her the telephone number he wants and the call goes through.
Three classes of mobile service are contemplated:
1. A general two-way telephone service between any regular telephone and any
mobile unit, with a three-minute initial period and one-minute overtime period.
2. A special two-way dispatch service between a particular telephone at the dispatching
office and specified mobile units. A direct line from the dispatcher to the telephone
central office would be furnished as part of this service. A one-minute initial
period and the usual one-minute overtime period would probably apply here.
3. A one-way signaling service to mobile units, to notify the operator of the
unit that he should comply with some pre-arranged instruction, such as calling his
office from the nearest public telephone.
Radio signals in the frequency range between 152 and 162 megacycles have been
assigned for the urban mobile service. In general, transmission of these frequencies
is greatly improved by mounting transmitting and receiving antennas on high buildings
or on other commanding elevations.
Transcontinental communications by microwave are envisioned
by Raytheon, which last month received construction permits for five stations to
form a relay circuit from New York to Boston. These five are the first leg of the
proposed route across the country, which will be extended via Cleveland, Detroit
and Chicago to the Pacific coast.
The company received at the same time constructional permits for two FM experimental
stations, to be erected atop the Lincoln Building, New York City. One of these on
105 megacycles, will transmit in a southward direction, while the other, on 107
mc, will beam its transmissions toward the west.
Swallow-Counting with the aid of electronics can indicate the
value of a trainee in actual aerial combat, according to reports issued by Westinghouse
last month. In high-altitude flying a definite relationship has been found between
the ease or difficulty of compensation of the flier for changes in altitude and
his ability as an air fighter. This altitude accommodation is made by swallowing,
which equalizes the pressure on both sides of the ear drum or tympanum. Regarding
the accommodation as a function of the rate of change of pressure is the chore of
the electronic tympanometer.
The tiny microwave transmitter fits in a case no larger than
a big telephone earpiece.
Heretofore, physicians have had to enter a high-altitude chamber with the prospective
flier and count the swallows, and relate them to the rate of change of pressure,
i.e., altitude. To make the examination more accurate and obviate the necessity
of the physician remaining in the high-altitude chamber during the test, instruments
that appear to be oversize earphones with "horns" have been developed at the Westinghouse
Research Laboratories. Clamped on the head of the flier, an earpiece over each ear,
the swallows are automatically registered by the instruments and recorded on a chart
outside the chamber.
Against each ear of the subject are placed fluid-filled chambers. The fluid rests
against the ear drum on one side, and on the other against a diaphragm in the "earphone".
The "earphone" is a microwave radio transmitter - the "horn" its antenna. The diaphragm,
coupled by the liquid to the eardrum, with each swallow moves a pin within the instrument.
This movement of the pin causes a peak in the transmitted wave. Thus, the record
of a compensation appears as a peak in an otherwise smooth graph.
The problem of transmitting the impulses to the recorder outside the high-altitude
chamber is essentially one of telemetering. Because the chamber is a metal enclosure,
the receiving antenna is strung inside, emerging by means of a coaxial cable. Accurately
plotted graphs of swallows versus altitude (or pressure) are made without the doctor
being required to undergo the discomfort involved in the high-altitude cycle.
Swallowing is a voluntary compensation for differences in altitude. There are
other entirely involuntary compensations of great importance in determining the
fitness of an individual for high-altitude. The end result of these involuntary
accommodations also equalization of pressure on both sides of the tympanum and the
rate of response of these to outside pressure variations is also shown.
Proposals to extend the standard-frequency broadcast downward
10 kilocycles, adding a new broadcast channel to the band, were tentatively approved
by the FCC last month. The Commission stated that about 54 percent of existing radios
will be capable of receiving stations on the new frequency.
Some objection has been raised to the proposal on the ground of possible interference
with the 50-Kc. international distress band. This can be avoided by spotting stations
on the new frequency in the interior, where there would be no possibility of blanketing
coastal areas with strong signals.
The proposal is supported by Howard S. Frazier, chairman of the Radio Technical
Planning Board Panel 4 on Standard Broadcasting, who is also chief engineer of the
National Association of Broadcasters. Mr. Frazier points out that the new channel
would be especially valuable in broadcasting for rural coverage, as the daylight
ground wave of a radio station has a greater range at that end of the broadcast
band, and the zone of serious fading is further from the transmitter.
Procedure for applying for permission to produce home radio
sets and other electronic equipment was announced last month by the Radio and Radar
Division of the War Production Board. As a result of this and other lifting of restrictions,
on materials for home radio manufacture, optimistic predictions of early commercial
production are circulating. Some of these insist that the first sets may come off
the production line in October. In any case, numbers are likely to be limited till
after V-J Day.
Direction 2 to Order L-265, gives instructions for filing Form WPB-4000 for permission
to build civilian radios and other electronic equipment restricted by the order,
under the provisions of Priorities Regulation 25, the "spot': authorization order.
Applicants for "spot authorization" to produce electronic equipment under PR-25
must include on the WPB-4000 application form a description of each type and model
of the product and the quantity (by quarters) to be produced. In addition, for each
type and, model to be produced, the proposed net unit factory billing value of the
equipment and a statement of the quantity of each of the following types of components
that are to be used in the manufacture of the equipment must be shown in a letter
filed with the application:
Tubes; Transformers and Reactors (excluding intermediate frequency and radio
frequency coils); Capacitors, fixed and variable; Resistors, fixed and variable;
Loud speakers; Switches; Sockets.
Favorable opinions on the new FM allocations were expressed
last month by a number of leaders in the industry. Though a number of them had pulled
for one of the alternate plans, all but a few feel that the final allocation has
rendered a real service by putting an end to uncertainty and making it possible
to proceed with confidence in the future.
Interference at the new frequencies is expected to be insignificant as compared
with the present band, the FCC stated. "Sporadic E" transmissions have been reported
by amateurs in the thousands between 56 and 60 megacycles, but none have been accomplished
between 112 and 116 mc, just above the present band, according to George Grammer
of the A. R.R.L., whose members have operated in both those bands. Interference
from the higher F2 layers, frequent enough to be troublesome at times below 84 mc,
is negligible on the spectrum.
Among those expressing satisfaction with the new band were William Halligan of
the Hallicrafters, John Ballantyne of Philco, and officials of Stromberg-Carlson,
General Electric and the American and Mutual Broadcasting Systems. Adverse reports
were filed by Arthur Freed of Freed Radio Corporation, and by Commander MacDonald
of Zenith Radio. Major Armstrong, who had been the most vigorous opponent of the
spectrum finally allotted by the FCC, expressed himself definitely by applying immediately
for permission to change his station WFMN to 92,100 Kc.
Items of the Radio Month
Libel by radio is made punishable by penalties ranging up to a $500 fine and
a year in jail by a law passed last month by the Illinois Legislature. Libel is
defined by the law as "Malicious defamation broadcast by radio tending to blacken
the memory of one who is dead, or to impeach the honesty, integrity, virtue or reputation,
or to publish the natural defects of one who is alive, and thereby expose him to
public hatred, contempt, ridicule or financial injury."
A mine detector was used by Sgt. Morris Press of the Eighty-Third Infantry Division
to find a missing watch. Losing his watch on the banks of the Rhine one evening,
he searched for it without success till dark. Next morning he borrowed a mine detector
and quickly turned up the missing timepiece.
Radios in Great Britain total 9,710,850 - or an average of one for every five
persons, according to a survey published last month by the British Post Office,
which controls all communications. The figure represents an increase of about 250,000
during the past year.
Electrostatic spraying of paint, in which the object to be sprayed is charged
to a high potential in one direction and the paint is oppositely charged, is expected
to save from 40 to 60 percent of the paint now wasted in spraying. Not only will
,all the particles approach and cling to the object sprayed, but their mutual repulsion
will tend to promote a more even spray and prevent "thick" and "thin" areas on the
part painted.
Radar was among the instruments used in observing the eclipse of the sun last
month. Radar instruments were part of the equipment of several scientific parties
making observations of the eclipse.
Zoning considerations may interfere with Washington television. Last month the
Zoning Adjustment Board of the District of Columbia denied the application of the
Bamberger Broadcasting Co. to erect a television tower in a residential district.
The decision - which was by a two-to-one vote - was made principally on grounds
of commercialization and property depreciation. The decision has attracted a great
deal of attention because of its possible recurrence in other cities, though Washington
is in a special position because its terrain renders erection of a satisfactory
television aerial in any other than a residential area a difficult problem.
One Billion dollars for the development of television in the
Soviet Union has been appropriated by the Russian government, according to reports
from Washington last month.
The Soviet investment of $1,000,000,000 in television virtually eclipses the
U. S. investment in video to date, which is estimated variously as "upwards of $30,000,000"
or "somewhere below $50,000,000."
1,000-Line television patent rights for the United States were
reported to have been purchased last month from their French owners by Columbia
Broadcasting System. Beside the rights for the French high-definition system, the
network is said to have purchased a number of other new foreign patents, covering
color television. Television engineers from France are expected to hold a demonstration
under CBS sponsorship shortly, in which the 1,000-line development will be revealed
to sections of the American public.
Ownership of FM stations will be limited to not more than six
for any individual or group proprietor, according to a tentative set of regulations
issued last month by the FCC. No person or group shall own, operate or control more
than one station in substantially the same service area.
Minimum operation of six hours daily will be required of the FM broadcasters.
At least one hour during the daytime period (8 am. to 6 pm.) and one hour during
the evening period (6 pm. to 11 pm.) must be devoted to "programs not duplicated
simultaneously in the same area by any standard broadcast station or any FM station.
During these two one-hour periods a service utilizing the full fidelity capability
of the FM station shall be rendered."
Posted January 29, 2022
(updated from original post on 7/8/2014)
|
