Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!shelby!agate!telecom-request From: 0004133373@mcimail.com (Donald E. Kimberlin) Newsgroups: comp.dcom.telecom Subject: Some Amplification on Color TV and FM History Message-ID: Date: 24 Feb 91 05:00:00 GMT Sender: usenet@agate.berkeley.edu (USENET Administrator) Organization: TELECOM Digest Lines: 148 Approved: Telecom@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 156, Message 1 of 3 X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu Re: Subject: The Year Was 1960 Continuing a thread that began in Digest V11, issue 123, Richard Budd commented on color TV in issue 128, > It's been available since the early 1930's, although before World War > II it was strictly experimental. Credits for the first color televison date to a Scot, Charles Baird, in 1927 experiments to produce color images by mechanical scanning methods. Baird was expanding on 1880's work that began with Senlecq's lab work on the photoelectric properties of selenium and Nipkow's development of image scanning with a perforated rotating disk. (In fact, there is some history showing facsimile by purely electric means dates to about 1847.) The problem of Baird's day was providing a transmission channel. Bell Laboratories was of course interested, and duplicated Baird's work, which in recent times has given rise to misleading AT&T television commercials that imply Bell developed color TV. In 1934, Philo Farnsworth (independently) and Vladmir Zworykin (at RCA) developed electronic image scanners. These resulted, combined with achieving sufficient radio bandwidth, in pioneering television broadcasts by the British Broadcasting Corporation commencing November 2, 1936, almost three years before American TV began at the 1939 New York World's Fair. Broadcast color television was stalled for a number of years while the Columbia Broadcasting System continued development of mechanical methods of separating primary colors based on Baird's work, in competition with RCA's work on extending Zworykin's electronic method. In their first iterations, both required broadcast channels far wider than the monochrome transmissions already on the air. The Federal Communications Commission of the US was unwilling to authorize use of so much radio spectrum for color television, and ultimately got the National Television Standards Committee to moderate a system for broadcast use. The RCA electronic method won out when it proved most compatible with existing monochrome methods. While both CBS and RCA method experimental transmissions had been aired, the final NTSC agreement was issued in 1953, permitting regular color transmissions to spread across the US after that time. Budd closed by saying that: > FM has also been around since the 1930's. Our Moderator, always the (rightfully) proud Chicagoan, replied: > The first FM radio station in the US was here in Chicago, started in > 1941 by the Zenith Radio Corporation. I have to take some issue there, Patrick. Just like transmitting pictures, FM has a physics lab history dating to 1862 work of Hermann von Helmholtz, amplified by Lord Rayleigh in England (a name famous to every radio engineer) in 1883. In 1925, John Carson at Bell Labs published on the value of using FM to reduce noise in communications links. It was (retired) Major E. H. Armstrong (to whom we owe credit for the superheterodyne receiver that made broadcast radio really a practical medium for the general public) who in 1935 aired the first broadcast FM transmissions in 1935, from a transmitter atop the Empire State Building to receivers in New Jersey. (Sorry, Chicago.) Both CBS at New York and Zenith at Chicago were early promoters of FM broadcasting. Coincidentally, Major Armstrong put a subcarrier on his 1935 transmitter, demonstrating multiplex transmission of audio programs with facsimile newspapers. He obtained a patent for FM that resulted in a bitter battle with AT&T about patent rights; one in which the classic "phone company stonewalling" often mentioned in the Digest may have resulted in Major Armstrong's suicidal hurling himself out of a New York office window. In a very complex argument involving the means of generating frequency-modulated versus phase-modulated signals, the Bell interests maintained their microwave transmitters did not violate Armstrong's patent, denying him of course millions of dollars in patent rights. Armstrong's method of generating FM required quite complex frequency multiplication, then downconversion, then remultiplication to achieve an output signal in the region below 50 megaHertz, which was in that era, the only one in which high-powered transmitting amplifers could be built. (FM radio before WW II was in the region 42-50 mHz.) Leave out the downconverter, and the result wound up at 600 megaHertz or more, a useless part of the radio spectrum in the mid-1930's. Bell Labs did this, and proceeded to develop means to focus super high frequency radio waves with reflector antennas that could work with only a fraction of a Watt of transmitter power, multiplexing at first 120, then 240 telephone voice channels on a single radio channel. Later improvements after WW II extended this to 600, then 1800 voice channels on a single microwave radio. In more recent developments, Bell Labs did pioneering work in polarizing antennas so microwave channels could be placed half as far apart in the radio spectrum, and most recently, modified the system to single sideband FM, obtaining a further doubling of the number of microwave radios that can be run along a given route. All this history became very personal when I first worked in radio stations that had on the transmitter plant wall, not only an FCC license to transmit, but also had a patent license issued by Armstrong's widow. Later, at AT&T, I questioned photos of TD-2 microwave equipment bays with covers enclosing them. An AT&T manager I worked with told me how he had seen them used only at New York, in early days when Major Armstrong would come to inspect with his lawyers. The AT&T employees were under instruction to keep the doors closed and not speak to Major Armstrong when he came to inspect the installation. I hope this rambling from the mists of telecom history is of interest and value to readers here. We owe far more to heroes who labored with balky, complex apparatus than modern histories ever seem to credit. [Moderator's Note: Thanks for another excellent article, which all of us have come to expect from your terminal. But I must question the FM thing a little. I listened to WEFM for *many* years, and they frequently discussed this. Of course it was over a dozen years ago the station changed format and I quit listening. My memory may be a little hazy. Was the station in New York on the air continuously on a regular schedule in the 1935 => 1941 period? Zenith's claim was they were the first on the air with regularly scheduled, commercial programming on the FM band. Of course, Zenith itself was the one and only sponsor for the lifetime of the station (as a classical station) for 36 years. The day the format changed in 1977 was a sad one. Everyone knew it was coming as Zenith had been trying to sell the station for quite some time. Metromedia finally agreed to buy the station but without the classical music format. Through a quirk, the FCC approved the sale, but did not approve the change in format for another year, so Metromedia, whose stations are easy listening and top forty rock found itself stuck with running a classical station for awhile. But when the change in format was approved, they wasted no time in the conversion. The FCC required them to give a week's notice to the listeners. A disclaimer was played hourly for a week advising that the FCC had given permission to change the format, and " ... for continued listening to classical music, we suggest you tune to WNIB or WFMT ..." On the final night, the last selection was Beethoven's Fifth Symphony, followed by their usual five minutes of news at 11:55 PM. At midnight they gave their usual sign-off announcement followed by the Naitonal Anthem, as was their custom. After about fifteen seconds of dead air, a nasal, obnoxious sounding voice told us we were listening to the home of top forty rock in Chicago. Their first selection was "Rock Around the Clock". The FCC made them keep playing the disclaimer once an hour for another week, then several times daily for a month. PAT]