RF Cafe Software
About RF Cafe
1996 - 2016
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Try Using SEARCH
to Find What You Need.
There are 1,000s of Pages Indexed on RF Cafe !
September 1945 Radio-Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles from Radio-Craft.
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.
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.
The automobile traveller would remain in touch with his home, even across the continent.
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 July 8, 2014