Signal interference and the FCC license freeze

[Rinehart]

I would like to get some information about the FCC license/CP freeze from September 1948 to April 1952. The FCC instituted it because they were unaware of the problems of signal interference when they allocated frequencies for television licenses near the end of the war.
My question is: why did they make such a mistake? One of conditions of obtaining a television broadcast license, either experimental from 1936 or commercial from 1941, was that the licensee had to have an active research program on this very subject. Did the stations provide faulty or incomplete information to the FCC, supplemented by guesses, or were there factors that they could not have anticipated at the time?
Also, since a television signal was propagated line-of-sight and its range limited by the radio horizon (10-15% farther than the optical horizon) why was there interference between stations hundreds of miles apart?

[Electronic M]

I believe that under certain conditions the transmissions in the VHF band can "skip" between the ionosphere and the earth like SW (sometimes called "world band") radio signals. I believe that prior to the war the only places where experimental broadcasts occurred in the US were NYC, Chicago, and LA. and I believe that most recievers were placed in the estimated good signal area of those stations. thus the full extent of the skip phenoninon was not able to be documented because no active recievers were present far enough away from the transmitters.

After the war there were many new stations and a comparative TON of new active recievers at all distances from the stations thus the FULL extent of the skip could be documented and recoreded. This new documentation I believe surpassed estimates based on previously documented info and led to the licensing freeze as the new info was analyzed.

This was a big headache for the FCC, but a big benefit for the TV mad public that bought and operated sets well outside of the estimated usable signal zone.

[Rinehart]

Yes, that seems a quite reasonable explanation--this had always been there, but it wasn't noticed until the rapid expansion of television after the war, and you feel that it was a good-faith error. According to the 1939 Broadcasting Yearbook, there were 23 licensed experimental stations as of November 1, 1938, some of which were in the large cities of the northeast, (7 altogether in NY, Philadelphia, Chicago, and LA,) and the rest scattered around the country, some of them in very unlikely places.
As of January 1946, there were 9 commercial stations and 26 experimental stations; by March 1947, 55 commercial and 63 experimental; by Jan 1948, 72 commercial and 91 experimental; at the time of the license freeze in September, 124 commercial stations (the Broadcasting Yearbook does not list experimental stations after the 1948 edition; all figures include construction permits granted.)
The FCC must have made an announcement on the subject, but when I looked through back issues of Billboard and Broadcasting Magazine I didn't see anything. If anyone knows where I might find it, please send me a PM.

[NowhereMan 1966]

I know here in Pittsburgh, we had WDTV on channel 3 which later became KDKA-TV and shifted to channel 2 because there was occasional interference with WNBK on channel 3 in Cleveland. We used to be with DuMont.

[electroking]

Originally Posted by Rinehart

...

Also, since a television signal was propagated line-of-sight and its range limited by the radio horizon (10-15% farther than the optical horizon) why was there interference between stations hundreds of miles apart?

Because that is not always true! A search on the topic 'TV DX' will tell
you more about this.

P.S.: this reference is good reading about this topic.

http://en.wikipedia.org/wiki/TV_and_FM_DX

[Jeffhs]

Originally Posted by NowhereMan 1966

I know here in Pittsburgh, we had WDTV on channel 3 which later became KDKA-TV and shifted to channel 2 because there was occasional interference with WNBK on channel 3 in Cleveland. We used to be with DuMont.

I always thought Pittsburgh was too far from Cleveland for such an interference problem to occur.

WNBK-TV in Cleveland (later KYW [1955-65] and now WKYC [1965 to present date]) started in 1948 on channel 4, so any interference problems would have been with channel 4 in Detroit, unless the latter signed on years after the Cleveland station.

I don't know when WNBK switched to channel 3; must have been before my time because, as long as I can remember, channel 3 has always been in Cleveland. (I am 55 years old and remember KYW, as well as when NBC purchased the station from Westinghouse in 1965 -- what a mess! Wikipedia has the full story on the Westinghouse-NBC fiasco in Cleveland, and believe me, it is very interesting reading).

Come to think of it, WNBK-TV on channel 4, and its switch to 3, was before my time, as the station had that call sign from 1948 until 1954.

BTW, the callsign WDTV, IIRC, is now held by the CBS TV affiliate in Weston, West Virginia. The station is on channel 5.

[NowhereMan 1966]

Originally Posted by Jeffhs

I always thought Pittsburgh was too far from Cleveland for such an interference problem to occur.

WNBK-TV in Cleveland (later KYW [1955-65] and now WKYC [1965 to present date]) started in 1948 on channel 4, so any interference problems would have been with channel 4 in Detroit, unless the latter signed on years after the Cleveland station.

I don't know when WNBK switched to channel 3; must have been before my time because, as long as I can remember, channel 3 has always been in Cleveland. (I am 55 years old and remember KYW, as well as when NBC purchased the station from Westinghouse in 1965 -- what a mess! Wikipedia has the full story on the Westinghouse-NBC fiasco in Cleveland, and believe me, it is very interesting reading).

Come to think of it, WNBK-TV on channel 4, and its switch to 3, was before my time, as the station had that call sign from 1948 until 1954.

BTW, the callsign WDTV, IIRC, is now held by the CBS TV affiliate in Weston, West Virginia. The station is on channel 5.

Interesting story there, I plan to read it. I know Westinghouse also bought a Cleveland radio station as during that time and it swapped the KYW callsign from Philly to Cleveland. I know there were some times I did get channel 3 from Cleveland during the analogue days so I think interference could be possible. It looks like this was during the days when they though 12 VHF channels would be enough but they were wrong. IIRC, when UHF came about, Youngstown, OH became a UHF market with 21, 27 and 33.

[Jeffhs]

Originally Posted by NowhereMan 1966

Interesting story there, I plan to read it. I know Westinghouse also bought a Cleveland radio station as during that time and it swapped the KYW callsign from Philly to Cleveland. I know there were some times I did get channel 3 from Cleveland during the analogue days so I think interference could be possible. It looks like this was during the days when they though 12 VHF channels would be enough but they were wrong. IIRC, when UHF came about, Youngstown, OH became a UHF market with 21, 27 and 33.

KYW-AM and TV were already under Westinghouse ownership when the stations were in Philadelphia. Westinghouse owned KYW-AM and TV from the mid-'50s to the mid-'60s, then they were moved to Cleveland in '65. NBC purchased the stations and promptly changed their callsigns to WKYC-AM and TV -- the callsign the television station still has today. WKYC-AM radio has had two callsign changes over the years -- WKYC-AM to WWWE (3WE) in 1972, then WTAM some time in the 1990s.

WTAM was WKYC-AM's original callsign when the former first signed on in Cleveland in 1923. The company (Clear Channel Communications of San Antonio, Texas) that owns today's WTAM radio changed the callsign from 3WE to WTAM, not only because the latter is the station's heritage callsign, but also, and in CC's opinion more importantly, because the callsign has the letters "AM" in it. For some reason, CC wanted a callsign for the former WWWE that had those letters somewhere after the W. It considered calls such as WUAM (rejected because of the similarity to and possible confusion with WUAB-TV channel 43, Cleveland's MyTV affiliate), et al., finally settling on WTAM. The station calls itself "Cleveland's only news radio" and operates with 50kW on 1100 kHz full time. As WKYC-AM, the station was a top-40 50-kW clear-channel rock-and-roll powerhouse, while its FM arm, WKYC-FM, played automated "elevator music" in stereo on 105.7 MHz. The latter is now known, again after several callsign and format changes since 1972, as WMJI "Majic 105.7" and plays what are now known as "classic hits", formerly referred to as oldies.

Since the abolition of the clear-channel rules in the mid-'80s, however, today's WTAM-1100 no longer has the fantastic nighttime coverage area it had during the WKYC-NBC era (and the 3WE days). Today, WTAM's signal is protected from interference for a distance of 750 miles in all directions, and there are now many former daytimers on 1100 now operating full-time on the frequency -- with lower power and directional signal patterns after local sunset.

Because of this, WTAM -- and almost all other former clear-channel AM stations in the United States -- can no longer claim the coast-to-coast coverage they enjoyed before the clear channels were abolished. The new rules were probably enacted to allow small-town, low-power former daytime-only stations to operate 24-7, so as to better serve the communities to which they are licensed. A station near where I grew up took advantage of this ruling about ten years ago; it formerly operated daytime only on 1330 kHz with 0.5 kW (500 watts). Thanks to the new rules, the station now runs 24-7, 0.5kW daytime and 0.042kW (42 watts) directional nighttime. An all-oldies station about 35 miles northeast of here also applied for and received permission a few years ago to operate full time on 1360 kHz, with 5kW daytime and 0.035kW (35 watts) directional at night. The station runs flea power with a sharply directional signal pattern after sundown Eastern time to protect, among others, 50kW WSAI-AM in Cincinnati, Ohio, also on 1360 kHz. WSAI is the "senior" station on 1360; as such it is entitled to and receives protection from interference by smaller stations on the frequency.

Note as well that, also due to FCC rule changes regarding AM broadcast stations' day and night power output levels, some stations assigned to frequencies such as 950, 980, etc. -- frequencies formerly used by low-power stations running well under 10 kW -- now operate with 50kW, at least during daytime hours, with much lower power and very sharply directional antenna patterns after local sundown. Stations that have taken advantage of this ruling include WXYT-AM 1270 in Detroit, WTEM 980 (formerly WRC-AM) in Washington, D. C., et al. Some stations in Florida (such as one station in Seffner, Florida, near Tampa) operate 50kW daytime and sign off at sundown. I feel sorry for people who live very near these stations' towers, as they must have the dickens of a problem with interference from that powerhouse 50kW signal. I bet the cable TV companies in those areas really have problems as well keeping the stations' signals from riding in on the cable, despite the fact that the cables connecting the subscriber's video gear to the cable system are shielded. My former landlord lives within a block or two of a 1kW day/0.5kW nighttime AM station; I bet her cable TV is shielded to the hilt, as even a 1kW signal at only two blocks is formidable and is capable of causing all sorts of interference problems to TV sets, et al. in homes close to the towers.

BTW, Youngstown, Ohio is not the only U. S. city to have UHF-only television service in its area. Fresno and Bakersfield, California are also UHF-only markets, as is Fort Wayne, Indiana. These cities apparently got on the television bandwagon after the UHF band was opened for U. S. television broadcasting. The reason UHF channels 14 to 83 (at that time, 1950s) were allocated to new TV stations in this country was that the old VHF band, channels 2-13, was becoming overcrowded, with interference problems in many areas. After the UHF allocation, all new TV stations in the U. S. were assigned to UHF channels.

Channels 70-83, however, were reassigned in 1970 to land-mobile and other non-video services; these channels were formerly used by translators and even by some commercial TV stations, when those stations first signed on. (I think Youngstown's WFMJ-TV channel 21, for example, was on channel 73 when it began service to the Mahoning Valley area; however, I don't know when the switch was made to channel 21.)

[Rinehart]

A correspondent of mine, a media historian, has pointed out to me something I wasn't aware of: that the FCC, in order to placate the broadcast industry, essentially ignored their own engineers and repeatedly reduced the distance requirement for both same-channel and adjacent-channel stations. It's the old story: hire high-priced talent and then ignore them. I have attached the sources she cited: Fifties Television by William Boddy and Stay Tuned by Sterling and Kitross.

[ha1156w]

Originally Posted by Jeffhs

Channels 70-83, however, were reassigned in 1970 to land-mobile and other non-video services; these channels were formerly used by translators and even by some commercial TV stations, when those stations first signed on. (I think Youngstown's WFMJ-TV channel 21, for example, was on channel 73 when it began service to the Mahoning Valley area; however, I don't know when the switch was made to channel 21.)

I'm puzzled. I had always understood 83-channel sets were sold up until the 1990's to make room for analog cellular phones. One could occasionally pick up a single side of the analog phone calls on old sets (being two-channel duplex). I don't recall seeing my first 2-69 set until well after knob-tuned sets were phased out. What was the initial changeover to 2-69?

[Jeffhs]

Originally Posted by ha1156w

I'm puzzled. I had always understood 83-channel sets were sold up until the 1990's to make room for analog cellular phones. One could occasionally pick up a single side of the analog phone calls on old sets (being two-channel duplex). I don't recall seeing my first 2-69 set until well after knob-tuned sets were phased out. What was the initial changeover to 2-69?

That was one reason channels 70 through 83 were eliminated on UHF TV tuners starting about 1990 or so -- the FCC did not want people listening in on cordless telephone calls. However, today's cordless phones, operating in the GHz (gigahertz) range, cannot be easily eavesdropped on since the actual frequencies within these bands on which the phones actually operate is never disclosed -- in the instruction manual or elsewhere. The same reasoning applies to cellular telephones, although, since these phones are mostly used by non-technical people, the frequencies or frequency bands on which the phones operate are never mentioned anywhere in the manual or even on the phone itself. Most people having and using cell phones, after all, could not care less how or over what frequencies their calls are transmitted; as long as the phone makes and receives calls, that's all they care about.

My Zenith Sentry 2 and also my RCA CTC185 color TVs have UHF tuners that stop at channel 69, not that any of this matters anymore with digital TV transmission. The UHF television band was butchered badly by the time DTV arrived; first the UHF band was channels 14-83 (1950s until 1970), then channels 70-83 were eliminated (1970s-late 1990s), and now, late '90s to today, the current UHF TV broadcast band, channels 14 to 55 or something like that. Since analog cable TV service is to be phased out by most cable operators in the not-too-distant future (and has been phased out in many areas already, even as I write this), it would not surprise me if even that range of channels is eventually reassigned to other services. Do not forget that the rationale behind switching TV from NTSC analog to ATSC digital, spectrum auctions, et al. was to clear the old analog TV channels so they can be utilized by other services.

I'm surprised you saw your first TV without channels 70-83 long after analog-tuned TVs were phased out. The only thing I can think of is that you must have seen a few older knob-tuned sets with detent UHF and VHF tuners that were being sold at dirt-cheap prices, just to clear out the store's old inventory. I forget the date, but some time in 2007 a law was enacted that made it illegal to sell new TVs with old-style knob tuning; this is why the stores sold these TVs, however many or few they may or may not have had left in their stocks, at such deep discounts. The ruling did not then and does not now apply, however, to used TVs sold on eBay, Craigslist, or other online auction sites, or through private sales (yard, garage, rummage sales, etc).

[Kamakiri]

Originally Posted by Jeffhs

I'm surprised you saw your first TV without channels 70-83 long after analog-tuned TVs were phased out. The only thing I can think of is that you must have seen a few older knob-tuned sets with detent UHF and VHF tuners that were being sold at dirt-cheap prices, just to clear out the store's old inventory. I forget the date, but some time in 2007 a law was enacted that made it illegal to sell new TVs with old-style knob tuning; this is why the stores sold these TVs, however many or few they may or may not have had left in their stocks, at such deep discounts. The ruling did not then and does not now apply, however, to used TVs sold on eBay, Craigslist, or other online auction sites, or through private sales (yard, garage, rummage sales, etc).

What was the reasoning for this law, any thoughts?