Radio Waves: “Tuning In The World”, Subcarrier Signals, SSTV Event from the ISS, the Zeptosecond and Israel Army Radio Shut Down

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Tracy Wood, Dennis Dura, John Forsyth, and the Southgate ARC for the following tips:

Tuning In The World (Far From Home)

When David Goren was 13 years old, he and his family went to visit their Uncle Lou.

“He was usually just railing about my long hair or criticizing rock and roll,” he recalled. But this time was different. “He gave me an old radio of his that had a shortwave band on it. I really didn’t know what that was. I asked my dad, and he was like, ‘You won’t hear anything on that!’”

David was curious, though, so after he got home, he turned it on, started fidgeting with the dial, and was amazed to discover sounds and music from around the world![…]

Click here to read the full post and click here to subscribe to the Far From Home podcast.

Subcarrier Signals: The Unsung Heroes of the FM Dial (IEEE Spectrum)

How subcarrier radio signals made room for hidden FM stations—and helped ensure that everyone has access to the news

A version of this post originally appeared on Tedium, a twice-weekly newsletter that hunts for the end of the long tail.

In our modern era, we tend to choose devices with as many functions as possible, and we bristle at the thought of an object with a single use—hence why umbrellas can be so frustrating to carry around. But sometimes, a single use case is exactly the right level of functionality. This is something I’ve been thinking about recently after I got my hands on a fairly large radio that has literally one function: You turn it on and a specific station plays, and there’s no surface-level way to do anything else with it.

This is a weird device—but for its niche, this device, called a subcarrier radio, was perfect. And it was one of many niches that subcarrier radios made possible.

What the heck is a subcarrier radio signal?
In 1985, a South Florida Sun-Sentinel article discussed a potentially lucrative offering for the owners of FM radio stations: ways to make extra money from parts of the licensed signal they weren’t already using.

This phenomenon was not unusual at the time; the practice had been around for decades. But what the article highlighted were the numerous ways radio signals were being used that the average listener was likely not even aware of—for background music, for stock reports, even to transmit computerized data.

And while station owners weren’t earning a ton of extra money—a single lease brought in US$1,400 a month (about $3,500 today)—for a struggling station, the additional revenue could mean the difference between being in the red and being in the black.

The thing that allows many radio stations to monetize their signals in this way is, essentially, a technical gap inside the FM broadcast signal. These gaps, or subcarriers, are frequencies that aren’t being used for the primary signal but could find secondary uses in more specialized contexts.[]

Amateur Radio on Shuttle, Mir and ISS (Southgate ARC)

ARISS report there will be an ‘Amateur Radio on Shuttle, Mir and ISS’ Slow Scan TV (SSTV) event from June 21-26. Transmissions from the International Space Station will be on 145.800 MHz FM using PD120

The ARISS team will be transmitting SSTV images continuously from June 21 until June 26. The images will be related to some of the amateur radio activities that have occurred on the Space Shuttle, Mir space station and the International Space Station.

The schedule start and stop times are:

Monday, June 21 – Setup is scheduled to begin at 09:40 UTC (transmissions should start a little later).

Saturday, June 26 – Transmissions are scheduled to end by 18:30 UTC.
Downlink frequency will be 145.800 MHz and the mode should be PD120.

Those that recently missed the opportunity during the limited period of MAI transmissions should have numerous chances over the 6 day period to capture many (if not all 12) of the images.

Check the ARISS SSTV blog for the latest information

The signal should be receivable on a handheld with a 1/4 wave whip. If your rig has selectable FM filters try the wider filter for 25 kHz channel spacing.

You can get predictions for the ISS pass times at

Useful SSTV info and links

Meet the zeptosecond, the shortest unit of time ever measured (

Scientists have measured the shortest unit of time ever: the time it takes a light particle to cross a hydrogen molecule.

That time, for the record, is 247 zeptoseconds. A zeptosecond is a trillionth of a billionth of a second, or a decimal point followed by 20 zeroes and a 1. Previously, researchers had dipped into the realm of zeptoseconds; in 2016, researchers reporting in the journal Nature Physics used lasers to measure time in increments down to 850 zeptoseconds. This accuracy is a huge leap from the 1999 Nobel Prize-winning work that first measured time in femtoseconds, which are millionths of a billionths of seconds.

It takes femtoseconds for chemical bonds to break and form, but it takes zeptoseconds for light to travel across a single hydrogen molecule (H2). To measure this very short trip, physicist Reinhard Dörner of Goethe University in Germany and his colleagues shot X-rays from the PETRA III at Deutsches Elektronen-Synchrotron (DESY), a particle accelerator in Hamburg.[]

Defense minister says he is sticking to plan to shut Army Radio (The Times of Israel)

Defense Minister Benny Gantz reiterated on Wednesday his belief that Army Radio should not continue in its current format as part of the Israel Defense Forces.

“I think that IDF soldiers must be kept as far as possible from any political involvement, and the station should be apolitical, and it has long stopped being so,” Gantz said in response to a query from Shas MK Moshe Abutbul on the Knesset floor. “I don’t think there is any way to operate Army Radio in its current form, largely due to the political angle.”[…]

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10 thoughts on “Radio Waves: “Tuning In The World”, Subcarrier Signals, SSTV Event from the ISS, the Zeptosecond and Israel Army Radio Shut Down

  1. Andrew

    Regarding subcarrier signals.. a well known electronics hobbyist shop in Australia used to sell an SCA decoder kit. If installed, it could receive literally *every* subcarrier on the FM band! I actually bought and installed the kit and was amazed at what could be heard. We didn’t have radio for the vision impaired or doctors’ radio, but I do recall supermarket instore radio, several foreign language services, a couple of Muzak channels and the BBC World Service. The kit used switchable bandpass filters to tune either the 67kHz or 92kHz subcarriers. Most of these services have since disappeared.

  2. Tom G. ABQ

    This may be a bit off topic. The author mentioned, “I got my hands on a fairly large radio that has literally one function: You turn it on and a specific station plays, and there’s no surface-level way to do anything else with it.” This reminded me of something I had when I was a young boy. My next door neighbor found out that I was into radio back in the mid 70’s. He was a volunteer fireman at our local station. He gave me radio that from the front looked like a stereo speaker box. It contained several vacuum tubes and the only control was a volume control on the back of the radio. It was tuned to 46.46 MHz which happened to be the frequency for our local fire station. It was also had a CTCSS squelch that allowed for rejecting other stations on the same frequency. I had a lot of fun listening to that fire radio even though it was quiet most of the time.

  3. Jim Tedford

    Some radio reading services have moved their programming online. In some cases, patrons have to register and get a password; some services just stream the content without any logins required.

    There’s a professional organization for radio reading services: They have links to a number of streaming services.

    These audio streaming services are meant for visually/print impaired people, and are all in part paid by tax dollars. They aren’t meant for sighted people. It’s technically illegal for you as a non-patron to listen to them.

    If you are a sighted person, and decide to listen, I suggest you send a donation to the organization that runs the service. It’s the least you can do.

  4. Jim Tedford

    A number of years ago I volunteered for my local library reading grocery ads for visually impaired patrons. The program aired on a subcarrier of the local NPR station. It was called the Evergreen Radio Reading Service. Patrons received a receiver from the library that picked up the signal. Later on I did a weekly program recording articles from various radio hobby and trade publications. There are a lot of blind folks who are radio enthusiats, and it was a very popular program.

    The library cancelled the program in the mid-2000s,saying that folks could find the same kind of content on-line. Not reallly – nobody records the weekly grocery prices for the visually impaired, and while there audio versions of a few radio hobby publications (like ARRL’s QST) there’s not a lot material available for the print impaired.

    1. Tom Servo

      One of my first volunteer experiences was reading Consumer Reports articles for the Alabama Radio Reading Service. It was actually quite fun! I had only done it a few times before they called me up to do a live reading of the local newspaper on air. I would have loved to have stuck with it but not too long after starting with the reading service I got a new job that entailed 70 hour work weeks and a two hour commute, so everyone else had to stop.

      It’s unfortunate that with the upgrade to HD radio, the SCA services had to be discontinued. Some stations use HD for radio reading services today (like WUWF in Pensacola) but my understand is the visually impaired struggle more with complex HD capable radios versus simple analog SCA radios, so it isn’t as popular.

      And you’re right about the lack of certain content online. Sure, the local grocery store likely puts their sales flyers online, but they’re in PDF format — and thus likely incapable of being parsed by the special text web browsers the print impaired depend on. Websites in general tend to really be bad about being reader-friendly, anyway.

      1. Jim Tedford

        Tom Servo, thanks for your post. I didn’t know that some FM stations are now using their HD channels for radio reading services.

        I can see how that would be hard for visually impaired folks to access HD-capable radios rely on touch screens and visual menus that are not accessible if you can’t see the screen.

        In the march of technology, for some it’s one step forward and two steps back.

  5. Zack S

    My local NPR station WDET, in Detroit lost its main transmitter and they ran a fund drive to replace it (I did contribute BTW). Their web page mentioned that they might bring back HDRadio broadcasts. I wrote to the station manager asking if they could run BBC World Service on one of the channels. She wrote back thanking me for that suggestion and also said that one of the things they want to use a HDRadio channel for was to replace their SCA radio reader service. I was surprised that SCA was still in use for the blind. Here is their Detroit Radio Information Service link and here is their program schedule I hope that they end up moving their SCA programming to HDRadio as I would listen to a lot of this programming.

  6. Henry LaViers

    I still have my GE Superadio II modified for Subcarrier reception on the FM band by much missed Bruce Elving at his FM Atlas Company in Esko MN. Bruce not only added the potentiometer tuned SCA mod but tuned and aligned the AM section on these “reconditioned” radios that he sold for $99. The SCA unit audio is scratchier than the later SCA units that have 3 crystal controlled sub-channels.

    1. Jim Tedford

      Many of us radio hobbyists miss Bruce Elving, I bought every issue of his FM Atlas and Station Directory, subscribe to his newsletter, and had a couple of the SCA-modified radios he sold.

      Since he passed, there’s been nobody in the monitoring hobby to publsh his indispensible books.


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