TV Broadcasting History - Various Articles
Picture Transmission and Television (1928)This is taken from the article "Radio Telegraphy and Telephony" in the 1929 World Almanac. The article was prepared by the information department of the American Telephone and Telegraph Company.
Since signals for the transmission of pictures or of television may be sent by either radio or wire, these matters are not restricted to the radio field. In this account of the development of the radio art, it therefore seems appropriate to describe chiefly those systems which have been demonstrated or are now in use, employing radio channels.
The "Photoradio" process used by the Radio Corporation of America for the facsimile transmission of material employs at the transmitting station a scanning process which effectively transforms the picture from a half-tone into a black and white dotted picture. In this way signals are transmitted at frequent intervals instead of continuously and the effects of the variable ether path are partly obviated. At the receiving end, chemically treated paper is darkened by the action of a jet of hot air under the control of the incoming signals. This process requires about one hour for the transmission of a picture and during 1928 continued in operation across the Atlantic between New York and London, and across the Pacific between San Francisco and Honolulu.
The transmission of weather maps by the U. S. Navy has continued using the apparatus developed by C. Francis Jenkins. This is a system by which weather maps are sent from Washington to some of the ships of the Navy at considerable distances.
The broadcasting of pictures by a few regular radio broadcasting stations, using frequencies in the broadcast band, has continued during the year 1928. Considerable interest in the reception of these pictures has been manifested by technically-minded listeners.
The most striking development in electrical communication within the last two years has undoubtedly been television. This was accomplished both by wire and by radio at the initial demonstration by the Bell System on April 7, 1927. The radio demonstration at that time consisted of the transmission of television signals from Whippany, N. J., 22 miles from New York, to the Bell Laboratories building in New York City where the speakers and performers were readily recognized on the receiving screen. The voices of the persons at Whippany were transmitted, and reproduced by means of a loud speaker.
At two demonstrations during 1928 the Bell Laboratories showed improvements in the television apparatus, the first consisting of the use of crystals for controlling the frequency of the transmitting and receiving apparatus, thus eliminating the necessity for the transmission of synchronizing current. The second demonstration was of the transmission of a scene in the open air, illuminated by ordinary sunlight.
The General Electric Company has also been active in this field and has demonstrated television upon a screen such as one would use for a home motion picture projector. Other parties, notably C. Francis Jenkins of Washington, have been active in television or the related field of picture transmission.
Various workers in Europe have aLso been engaged in the study of optical transmissions by electricity. Baird in England has used both visible and infra-red light and is also reported to have demonstrated the reproduction of television images in color. In Germany, Karolus has perfected a cell through which light passes in variable amounts under the control of an electric field. This furnishes a rapid method of varying an intense beam of light. In France, Belin has also conducted investigations on optical transmissions, using the cathode ray oscillograph.
On account of the great popular interest in television, it should be explained that the apparatus required is rather elaborate and that even under laboratory conditions the art has not yet come to near the stage of development required to reproduce scenes with the fineness of detail of the regular motion picture.
New York Times, Sept. 23, 1945Television station WABD discontinued its programs after its sign-off last Thursday night and will not be back on the air until Dec. 15. In the interval the station will shift from channel 4 (78 to 84 megacycles) to its newly assigned channel 5 (76 to 82 megacycles), a position in the spectrum not heretofore assigned to the New York area.
During the interim period between telecasts, DuMont engineers are making arrangements to assit set owners in modifying their receivers to receive programs on the new band.
Rules and Regulations Governing Visual Broadcasting
Feb. 18, 1929The Federal Radio Commission has adopted the following rules and regulations governing visual broadcasting:
That visual broadcasting be designated to include both television broadcasting and picture broadcasting, or moving-picture broadcasting and still-picture broadcasting, and that all licensees issued to be of an experimental nature for a period of six months only, the licensees to report to the commission the results of their experiments; the transmitters to be located outside the city limits and sufficiently distant from important receiving centers to avoid interference.
For joint use to visual broadcasting licensees the commission authorizes the following bands of frequencies for experimental use only; 2,000 to 2,200 and 2,750 to 2,950 kilocycles. In addition, the commission will authorize the operation of visual radio broadcasting transmitters in the band between 2,200 and 2,300 kilocycles, on the condition that they do not interfere in any way whatever with the services of any other nation on the North American Continent and in the West Indies, and that licenses be subject to revocation in case there are any complaints from any other nations of any such interference. The commission may continue to issue experimental television or visual licenses in the broadcast band for operation between 1 and 6 a.m. only, in accordance with General Order 50.
The commission adopted the following rules of priority in the granting of applications:
1. Those engaged in experimentation to improve the technique of visual broadcasting.
2. Those who employ methods which give the maximum definition with the minimum radio frequency band widths.
Book ExcerptThe following is excerpted from The Radio Manual (for Radio Engineers, Inspectors, Students, Operators and Radio Fans), Second Edition, September, 1929, by George E. Sterling (Radio Inspector, Radio Division, U. S. Department of Commerce), published by D. Van Nostrand Company, New York.
2. Early Developments -- In June, 1925, Mr. C. Francis Jenkins gave the first public demonstration or the transmission of images of living subjects, and also of film records of persons and scenes. Mr. Jenkins effected his transmission by radio and in the latter case called his images of living subjects "radio vision," and his transmission of films "radio movies." In April, 1927, the American Telephone and Telegraph Company transmitted images of living persons from Washington to New York over telephone circuits. The same sort of images were also transmitted by radio from the A. T. & T. experimental station at Whippany, N. J. to the laboratories in New York City. In the considerable publicity given to the A. T. & T. transmissions the term "television" was used, and has largely been adopted by the general public as applying to any form of visual broadcasting. One cannot well quarrel with established usage, even though incorrect, but a discrimination should be made between the radio transmission of living subjects and transmission of film records of such subjects. Therefore in this chapter we will call the first system "television" (meaning radio vision, although the term does not say so) and the second one "radio movies."
Now observe that in the A. T. & T. demonstrations wire and radio channels were used interchangeably. Thus the art of seeing at a distance is not necessarily a radio art and the reason for introducing it into a radio book lies in the expectation that some form of it will see wide distribution as an auxiliary to the present (acoustic) radio broadcasting. Independent wire development for public entertainment can be expected.
3.) Radiomovies -- Radiomovies are made possible by first photographing the subject with an ordinary motion picture camera. The problem then becomes that of transforming the lights and shadows of this film into electrical impulses which can be transmitted and at the receiving end reconverted into lights and shadows properly distributed on the receiving screen. Since in the ordinary moving picture theatre a flickerless picture necessitates running the film through the projector at the rate of about 16 pictures per second, we must carry out our process of conversion at this same rate, which is to say, we must in 1/16 of 1 second completely transform one "frame" or picture into electrical impulses and move it on so that the next "frame" may be similarly analysed in the next 1/16 of 1 second. The process of doing this is basically the same one of "scanning line-for-line" as is used in transmitting directly the image of a living person. However, the small size of the film permits some surprising simplifications and economies of the apparatus and without doubt the greatest accomplishments have been made along the line of transmitting and receiving silhouette and half-tone radiomovies. As transmitted from the Jenkins station W3XK, these have been well received over a considerable portion of the United States.
The first radiomovies transmitted from the Jenkins Laboratories were only silhouettes in order to confine the frequency...
29. Rules and Regulations of the Federal Radio Commission governing the Operation of Visual Broadcasting -- That visual broadcasting be designated to include both television broadcasting and picture broadcasting, or moving picture broadcasting and still picture broadcasting, and that all licenses issued be of an experimental for a period of six months only, the licensees to report to the Commission the results of their experiments; the transmitters to be located outside of the city limits and sufficiently distant from local programming centers to avoid interference.
For joint use to visual broadcasting licensees, the Commission authorized the following bands of frequencies for experimental use only: 2000 to 2200 and 2750 to 2950 kilocycles, on the condition that they do not interfere in any way whatever with the services of any other nation on the North American Continent or in the West Indies, and that licenses be subject to revocation in case there are any complaints from any other nation of any such interference. The Commission may continue to issue experimental television or visual licenses in the broadcast band for operation between 1 and 6 a. m. only, in accordance with Central Order 50.
The Commission adopted the following rules of priority in the granting of applications:
1. Those engaged in experimentation to improve the technique of visual broadcasting.
2. Those who employ methods with give the maximum definition with the minimum radio frequency bandwidths.
LIST OF VISUAL BROADCASTING (TELEVISION) STATIONS CALL LOCATION LICENSEE FREQUENCY POWER W1XAE 624 Page Blvd., E. Springfield, MA Westinghouse Elect. & Mfg. 2.0 - 2.1 20.0 W1XAY Adams Street, Lexington, MA J. Smith Dodge 4.8 - 4.9 0.5 W1XB 63 Gorham Street, Somerville, MA General Industries 2.1 - 2.2,
0.5 W2XBA Newark, NJ WAAM, Inc. 2.75 - 2.85 0.05 W2XBS 70 van Cortland Pk. S., New York, NY (portable) Radio Corporation of America 2.0 - 2.1 5.0 W2XBU Beacon, NY Harold E. Smith 4.8 - 4.9 0.1 W2XBV New York, NY (portable) Radio Corporation of America 2.0 - 2.1 5.0 W2XBW Initial location: 70 River Road, Bound Brook, NJ (portable) Radio Corporation of America 2.0 - 2.1 5.0 W2XCL 323 Berry Street, Brooklyn, NY Pilot Electric Mfg. Co. 2.0 - 2.1,
2.75 - 2.85
0.25 W2XCO New York, NY (near) Radio Corporation of America 2.1 - 2.2 5.0 W2XCR 346-70 Claremont St., Jersey City, NJ Jenkins Television Corp. 2.1 - 2.2 5.0 W2XCW 1 River Road, Schenectady, NY General Electric Company 2.1 - 2.2 20.0 W2XR 140 Nassau Street, New York, NY John V. L. Hogan 2.0 - 2.1,
2.1 - 2.2
0.5 W2XX Overton Road, Ossining, NY Robert F. Gowen 2.0 - 2.1 0.1 W3XK 1519 Connecticut Ave., Washington, DC Jenkins Laboratories 2.0 - 2.1,
2.85 - 2.95
5.0 W3XL River Road, Bound Brook, NJ RCA Communications 2.85 - 2.95 30.0 W4XE Winter Park, FL William J. Lee 2.0 - 2.1 2.0 W6XAM Washington & Oak Sts., Los Angeles, CA Ben S. McGlashan 2.0 - 2.1 0.5 W6XC 5155 S. Grammercy Place, Los Angeles, CA Robert B. Parrish 4.5 - 4.6 15.0 W7XAO Portland, OR Wilbur Jerman 2.75 - 2.85 0.1 W8XAV E. Pittsburgh, PA Westinghouse Elect. & Mfg. 2.0 - 2.1,
2.1 - 2.2,
2.75 - 2.85
20.0 W9XAA Foot of Grand Avenue, Chicago, IL Chicago Federation of Labor 2.0 - 2.1 1.0 W9XAG 1768 Wilson Avenue, Chicago, IL Aero Products, Inc. 2.0 - 2.1 1.0 W9XAO 6312 Broadway, Chicago, IL Nelson Bros. Bond & Mortgage 2.0 - 2.1 0.5 W9XAZ Iowa City, IA University of Iowa 2.0 - 2.1 0.5 WRNY Hudson Terrace, Coytesville, NJ (1 to 6 am only) Aviation Radio Station, Inc. 1010 kc. 0.25
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