37’s Signals

Explaining why analog television sets never had a channel 37, despite TVs generally able to tune it. Turns out some scientists simply needed that channel more.

By Ernie Smith

Today in Tedium: I’m endlessly fascinated by stories of the quirks that were built into the TV system where the well-laid plans of the system simply fell apart because it was asked to do too many things. Nearly five years ago (I know, crazy!), I wrote about one of them, the tale of how radio broadcasters were able to shoehorn an additional FM station into the radio because of the proximity of TV’s channel 6 to the rest of the radio feed. So when I was informed that there was another oddity kinda like this involving the TV lineups, I decided I had to take a dive in. (This piece is being written in honor of Matthew Keys, who can predict the future.) Today’s Tedium talks about the odd state of channel 37, which couldn’t fend off its scientific competition. — Ernie @ Tedium

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The year that the U.S. Federal Communications Commission opened up the television system to use UHF, or ultra high frequency signals. The practical effect of this addition of bandwidth was that the total number of potential TV stations increased dramatically, from 108 to 2,051, overnight. The first UHF applications were granted on July 11, 1952, according to The History of UHF Television, a site dedicated to the higher-frequency television offerings.

Radio Telescope

The radio telescope at the Vermilion River Observatory, near Danville, Illinois. (University of Illinois)

The radio telescope that became a headache for the television industry

Within a 600-mile radius of the city of Danville, Illinois, population 31,246, are numerous major cities—among them Chicago, Detroit, Milwaukee, Atlanta, Minneapolis, Pittsburgh, St. Louis, Toronto, and Washington, DC.

Nearly the entire length of the Mississippi River fits into that radius. If Danville was located just a little farther to the east, the radius would also include Philadelphia and New York City. For all intents and purposes, a 600-mile radius from Eastern Illinois covers basically the entire East Coast except the state of Florida and the Northeast.

(Importantly to this story, New Jersey generally does not fall into this 600-mile radius.)

But there was something located in Danville that was important enough to scientists that they didn’t want to share it with anyone else.

And that thing was a 400-foot-wide radio telescope, operating along the 610 MHz frequency. It was something of a monster of astronomy at the time, operating 12 to 16 hours per day, and researchers at the University of Illinois aimed to keep it that way.

The research that led to the creation of the radio telescope was, basically, an accident—but a fundamental one that taught us more about the universe than we might have learned with a mere optical telescope.

In 1931, a radio engineer and Bell Laboratories employee named Karl Jansky was trying to uncover the source of static that was interfering with radio waves … and found it had an extraterrestrial source, particularly at the center in the Milky Way galaxy.

Jansky wasn’t an astronomer, but an engineer, and despite discovering a new field of astronomy, his position at Bell Labs did not allow him to pursue it further.

George Swenson

George Swenson of the University of Illinois, who helped build a radio telescope for the school. (via the National Radio Astronomy Observatory)

But after World War II ended, others eventually did pursue radio astronomy, including George C. McVittie, a British cosmologist who built the astronomy department at the University of Illinois in the 1950s, and George Swenson, who helped to build the university’s radio telescope.

Speaking to the Royal Astronomical Society as part of an oral history in 1978, McVittie, who played a central role in the creation of the telescope, stated that the device was developed in the late 1950s with a goal of being cost effective:

Well, we wanted to build this parabolic cylinder. I sent George Swenson on a tour of radio astronomy outfits in the world, Australia, England and so on, and he came back with the idea of the parabolic cylinder, a fixed transit instrument that sweeps out the sky simply by the earth rotating. And we decided for engineering reasons that we could only build a really big one if we had a frequency round about 600 megahertz. Otherwise, the perfection of the reflector, if we went to a shorter wavelength, was not something that you could [do] by the acre, at least not at that time, which was the late 1950s. And so we picked upon this 610 megahertz band as the observing frequency.

(The telescope was more expensive to maintain than to build, McVittie added.)

The area around the 610 MHz band has, over the years, gained a reputation as being important to scientific research because of its placement in the context of two other frequencies important to radio astronomy, 410 MHz and 1.4 GHz.

As space and astronomy writer Bob King of Universe Today put it in 2013: “Without it, radio astronomers would lose a key window in an otherwise continuous radio view of the sky. Imagine a 3-panel bay window with the middle pane painted black. Who wants THAT?”

There was just one problem—the sudden, high popularity of television made the general bandwidth area where the telescope operated, 608-614 MHz, a bit of a hot commodity. It was literally the spot where channel 37 was supposed to go—and broadcasters wanted access to that channel.

It threatened to cover up a key window.


The number of stations that had been allocated to use channel 37 in the U.S. in 1952, according to The History of UHF Television. One of those communities was Paterson, New Jersey, located within the New York City metro area—which is relevant to this story. In the end, no channel 37 actually ended up on the air in analog form in the U.S., though you may find a digital equivalent today thanks to differences in how signals are allocated.

Television static

(Patrick Tomasso/Unsplash)

Why the existence of channel 37 became such a problem for scientists

At the time the University of Illinois had built out its radio telescope, television was still in its infancy, and not every TV could actually access UHF signals. But soon, UHF went from optional upgrade to standard feature on television sets, and that meant this radio telescope was in the way.

Fortunately for the scientists that relied on this telescope, they had the support of the global community. A meeting of the International Telecommunication Union in 1959 set aside a series of frequencies that were important for different scientific and technical uses. One of those frequencies was where channel 37 sat.

The University of Illinois, wanting to protect its radio telescope investment, went to the FCC basically immediately after the ITU meeting. In 1960, it asked that channel 37 be allocated to radio telescopes exclusively.

As McVittie recalled, fellow scientists considered the decision to block out an entire television channel a big ask:

Most of our radio astronomy friends said, “Look here, you two, Swenson and McVittie, you are just crazy. Do you mean to say you are asking the American public to give up one television channel for science? Who ever heard of anything so absurd?” So we said, “Well, the channel isn’t being used.” “Yes, that’s true, it’s not being used very much but it is being used in the neighborhood of New York, and places like that.” So I said, “We’re not in the neighborhood of New York.” Anyway, we got laughed at.

The FCC disagreed with the university’s assessment, feeling that it was too early to make such a call.

But just a couple of years later, stations were starting to call the FCC up for access to that specific station—particularly one directly outside of the antenna’s 600-mile radius, in New Jersey. (According to reports from the era, prospective broadcasters wanted to put a Spanish-language network in the spot.)

Because of FCC rules and limitations elsewhere, the city of Paterson had no other options to bring a TV station on air other than channel 37. But even with the channel being located hundreds of miles away and targeted at the New York City market, there was concern among scientists that even far-away interference could get in the way of scientific research.

The regulators, faced with a conflict that pitted a niche use case against a massive commercial windfall, tried to come up with a compromise. The compromise included:

  • No stations on channel 37 within a 600-mile radius of the antenna until at least 1968, allowing one specific scientist, McVittie, to complete a survey of radio star sources he was doing on the 610 MHz frequency.
  • No stations anywhere listed under channel 37 could air anything between midnight and 7 a.m. Keeping in mind time zones, this effectively would give McVittie four hours a night that were open to allowing for such research.

The FCC’s attempt to balance science and commerce was not well-accepted by said scientists, who took their story to the media.

The controversy was such that it appeared on the front page of The New York Times. Not the top, of course.

What initially was seen as an absurd ask, even a silly one, gained momentum among fellow scientists. A letter sent to the FCC in regards to the debate puts the passion around the conflict into focus: “The FCC Docket suggests an appalling lack of comprehension within the FCC of the nature and needs of radio astronomy and yet the Commission has power to cripple and perhaps even destroy radio astronomy.”

That’s from an October 1963 document from the FCC that announced the commission’s decision to bar the use of channel 37 in the U.S.—while encouraging its neighbors in Canada and Mexico to do the same.

(The FCC did defend itself against the observer’s claim, writing: “Assertions charging the Commission with a lack of comprehension of the nature and needs of radio astronomy and implications that the Commission might cripple and even destroy radio astronomy are unjustified and can not be supported by facts.”)

The FCC agreed to a 10-year moratorium on channel 37 being used, which eventually became permanent.

The fun part about this is that McVittie, who helped to set the wheels in motion for the blanket ban of channel 37 in the U.S., never learned exactly why the FCC made the decision to flip its mindset on this issue. He speculated that media attention put the issue in front of the average person, allowing for wide-scale public support to mount up in favor of radio astronomy:

Somehow the news got around that here was this new way of listening to little green men on Mars. This is what radio astronomy seemed to the ordinary public. And the FCC was preventing it from being developed in the United States. We got rumors, George particularly from friends he knew, that gradually a huge accumulation of letters arrived at the FCC, protesting against this nonsupport of this new science, whatever it was. And that this finally persuaded the FCC that they’d better give in. Nobody knows.

Fortunately, we have the document explaining their thinking, and the thinking was essentially this:

It is probable that channel 37 operations at Paterson, New Jersey would interfere with observations at Danville to a certain extent. Also, (since interference from different sources would probably not occur simultaneously) the situation would be complicated by interference from other channel 37 stations if authorized. Moreover, any interference which would exist, even though for only a small percentage of time, might occur at critical times in the observing process. To the extent that observation programs would be interfered with, the time of completing them might well be substantially increased, so that a longer period of protection would be required to achieve the same results.

In other words, they didn’t necessarily know how putting channel 37 on the dial was going to impact scientific research in the long run, so best not risk it.

Ultimately, channel 37 went completely unused throughout the analog era in much of North America as well as most other countries—with a handful of exceptions, particularly in the Caribbean countries of the Dominican Republic and Trinidad and Tobago. (Today, channel 37 technically can appear as an over-the-air digital channel, but it is usually a so-called “virtual channel,” allowing a network to be positioned there no matter its position in the spectrum.)

In the end, the scientists won.


The year that the FCC allowed for the use of wireless medical telemetry services (a.k.a. devices that allow for the tracking of patient vitals, like heartbeat, wirelessly) on the same band as channel 37. “Despite existing constraints in these bands, this allocation is flexible enough to allow spectrum to be available for medical telemetry services in all locations while protecting radio astronomy and government operations currently operating in the allocated spectrum,” the commission said at the time. Despite occasional rumors that the spectrum would go unlicensed eventually, it has yet to happen.

The tale of channel 37 reflects one thing: Without resistance, a commercial use case will usurp a noncommercial use case for a given resource.

A 1963 op-ed in The Harvard Crimson put it best: “Because the communication industries try to send strong signals to all parts of the globe and radio astronomy tries to receive weak extra-terrestrial signals, the growth of these two fields must inevitably lead to conflict.”

Think about this in terms of other things that have nothing to do with astronomy, like the internet. A year or two ago, there was a big conflict involving who owned the .org top-level domain, with commercial interests attempting to hone in on something intended to support nonprofits. The only reason it didn’t happen, just like the Channel 37 saga, was because people in the world of nonprofits and technology came together to lobby against it.

Ultimately, in the case of channel 37, scientists were able to save a small sliver of what was mostly going to be otherwise used commercially. Perhaps it looked like static to everyone else—but it was worth fighting for.


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Ernie Smith

Your time was just wasted by Ernie Smith

Ernie Smith is the editor of Tedium, and an active internet snarker. Between his many internet side projects, he finds time to hang out with his wife Cat, who's funnier than he is.

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