Category Archives: AM

Unlocking Rare DX Treasures with SDR-Console’s Powerful Data File Analyzer Tool

Finding Rare DX with the Data File Analyzer

Don’s DX traveling stories can be found in his book Tales of a Vagabond DXer.

I’ve been a real jack-of-all-trades in my over five decades of DXing. I began with SWBC (shortwave broadcast) but soon branched out to medium wave and voice utility. Later I added longwave beacons and more recently I’ve gotten into digital utility stations. My goal has always been to log lots of different stations from lots of different places. And the rarer they are, the better.

For SWBC and medium wave stations, as well as scheduled utility broadcasts such as marine and aeronautical weather reports, the DXing process is simple. You tune to a frequency at a time when a station is scheduled to be on the air. It’s either there or it’s not there. If it’s not there then maybe propagation isn’t right or maybe your antenna/receiver setup isn’t the best for that frequency band or the station’s power level. You tune away to find something else with plans to try again another day.

But it’s not always that easy. Most utility stations do not have fixed schedules and only come on as needed. The best example of that is two-way marine, aeronautical, and military voice communications.

In eastern North America, tune to 8906 kHz anytime from late afternoon until morning and set your receiver to USB mode. You’ll probably hear empty static at first but it’s unlikely that more than ten or fifteen minutes will pass before you’ve heard some aeronautical traffic. The frequency is assigned for communication on the North Atlantic and is heavily used by aircraft communicating with New York Radio, Gander Radio (Newfoundland, Canada), and Shanwick Radio (Shannon, Ireland). If you keep listening, the frequency will probably be occupied around 25% of the time. Wherever you are in the world, there are a few heavily used air frequencies like 8906 kHz and listening to them can be fascinating. But I want to log more than just a few easily heard stations.

Sticking to aeronautical DX, there are many assigned frequencies for different regions and air routes around the world. But propagation to those distant areas is unpredictable and less-used routes have fewer flights. Fewer flights mean less radio communication and more empty static. The most interesting frequencies may only see traffic a few times a week.

Hearing the rarest voice utility DX requires listening to lots of empty static just to get a brief DX catch. For years my process was simple. I would set my receiver to an interesting frequency and leave the tape recorder running while I sat nearby listening and doing something productive. I got some very good DX over the years that way. But I don’t want to think about how many long hours of empty static I listened to in order to get that DX.

SDRs offered some improvement. Instead of audibly monitoring a specific frequency I could now make a spectrum recording that included a band of interest, say the 8815 to 9040 aeronautical band. During playback I could visually monitor the SDR waterfall for interesting signals. That works. But watching an SDR waterfall scroll by for three or four hours gets tedious quickly.

(When I refer to SDRs, I mean ones consisting of a small box that is connected to and controlled from a computer using a software program. None of this applies to models such as the Malachite line or the Icom IC-R8600, which use SDR technology inside but mostly function as a traditional receiver.)

Finding a Better Way

That better way is, I think, one of the most exciting DX tools out there – the Data File Analyzer in the SDR-Console program. Since I learned about it a few years ago, the Analyzer has gotten me all kinds of catches that I probably wouldn’t have gotten otherwise. Let’s start with an overview and then dig into the how-to.

SDR-Console is one of the better-known SDR programs and it works well with most of the common SDR radios on the market, including the Airspy, Elad, Perseus, and SDR-Play models. Here’s what the main window looks like:

The Data File Analyzer is a second window that produces a scrollable waterfall display for the entire length of an SDR spectrum recording. The display is similar to a standard waterfall with frequencies along the bottom and times along the side. However, there is also a scroll bar on the right side for browsing through the entire length of the recording. Instead of watching a four-hour spectrum recording slowly roll by in real time, I can scroll through the window looking for DX.

And this is what makes the Data Analyzer really useful. When I spot an interesting signal, I click on it and that causes the main window to start playing at that time and frequency. Now going through a four-hour spectrum recording takes from a few minutes to around half an hour, depending on how much DX I find.

Here’s a closeup of part of that same screen of spectrum recording made on 24 October 2024 at a DXpedition in western Pennsylvania, USA.

“A” marks a short exchange between an aircraft and Ndjamena Radio in Chad on 8894 kHz. “B” is Niamey Radio in Niger on 8903 kHz. “C” is Gander Radio on 8891 kHz. Just to the left of that is a string of digital signals. “D” is New York Radio on 8918 kHz. Again, there is a string of digital signals just to the left. Finally, “E” is communication from Dakar Radio in Senegal and Sal Radio in the Cape Verde Islands on 8861 kHz. I caught four African aero stations in just four-and-a-half minutes. I could also show you long stretches of time when there was nothing interesting coming in. With the Data File Analyzer I was able to visually find and focus on the DX and not waste my time with the empty static.

Here’s another image taken at the same DXpedition. Notice the three transmissions between 8820 to 8845 that seem to be mirroring one other.

That turned out to be Flightwatch Brisbane, the Australian regional aeronautical network. It uses multiple transmitter sites on 8822, 8831, and 8843 kHz to cover the entire country. I had never logged it before and I doubt I would have found it if DXing in the traditional manner.

The How-To

Here I’m going to assume that you already have SDR-Console installed and know the basics of how to use it, including making spectrum recordings. (If not, see the links at the end.) This article was written using version 3.4 of SDR-Console. Some of the functionalities described are not in earlier versions, so upgrade if you are not up to date. And I should point out that while you can do this on a single monitor, it works more smoothly if you have a dual monitor setup and can put each window on a different screen. Continue reading →

From NDBs to TIS: A DXer’s Journey Across 1610-1700 kHz

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Many thanks to SWLing Post contributor Dan Greenall, who shares the following guest post and asks, “Wonder who can add to this list?“:

A Look Back – DXing between 1610 and 1700 kHz

by Dan Greenall

1. The Caribbean Beacon, Anguilla West Indies 1610 kHz (1985 QSL)

2. NDB stations (non-directional beacons)

transmitted call letters on CW, mostly from airports, heard in the 1970’s
examples: MDE Medellin, Colombia 1690 kHz and RAB Rabinal, Guatemala 1613 kHz

3. U.S. Army Broadcasting Service KTRK 1670 Fort Meade, MD Feb 1996 articles and recordings

https://www.radioheritage.com/ktrk-k-truck-1670-khz/

4. FCC Part 15 Radio Stations

Example: WDKW 1630 “the Klaw” Dundalk High School near Baltimore, MD

Link to my recording made at a DX camp in Coe Hill, Ontario, Canada on April 20, 1997: https://archive.org/details/wdkw-the-klaw-1630

An internet search revealed the following;

Part 15 of the Federal Communications Commission (FCC) rules allows some low-powered radio devices to operate without a license on the AM and FM radio broadcast bands. These devices are subject to certain restrictions, including:

Range: On FM frequencies, the effective service range is limited to about 200 feet (61 meters).
Field strength: The field strength should not exceed 250 ?V/m (48db) at 3 meters.
Detachable antennas: Part 15 rules prohibit detachable antennas on all Part 15 transmitters.

Some examples of Part 15 radio stations include:

Microbroadcasting

Often used by hobbyists, drive-in theaters, or on college or high school campuses.

Talking roadsigns, talking houses, or talking billboards

These transmitters air a repeating loop of information, such as traffic or highway construction. They typically operate on empty channels on the AM broadcast band.

InfOspot

A custom product that can include special audio systems, USB / internet connectivity, cabinets, and antenna mounting styles.

Free-radiate AM radio stations

Educational institutions can use a transmitter without a license if the signal coverage is limited to their property.

5. TIS (Travellers Information Stations)

1610 kHz with low power, usually around 10 watts, such as the one I hear near the Blue Water Bridge between Sarnia, Ontario and Port Huron, Michigan

6. Expanded AM broadcast band

Over a quarter century ago, these frequencies began to be used in the U.S. by BCB stations. I still have recordings of a half dozen of these from the early days.

WTDY 1670:

WNML 1670:

WMDM 1690:

KCNZ 1650:

KCJJ 1630:

KBGG 1700:

Also, here is a link to a column in Popular Communications magazine from February 1998.

https://www.worldradiohistory.com/Archive-Popular-Communications/90s/Popular-Communications-1998-02.pdf

Don Moore’s Photo Album: Chota, Peru

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Don Moore’s Photo Album: Chota, Peru

by Don Moore

More of Don’s traveling DX stories can be found in his book Tales of a Vagabond DXer.

For DXers of Latin American stations, the period from about 1978-1998 was the golden age of DXing Peru. Those years saw an explosion of shortwave broadcasting from small towns, especially in northern Peru. Most of the stations were unlicensed and few lasted long. I tell the complete story of the period in Tales of a Vagabond DXer. However, the book doesn’t have many pictures as that would have made it much more expensive to produce and to buy. Fortunately, this blog is a perfect place to share photographs.

In those days one of the biggest radio hotspots in Peru was the department of Cajamarca. Over one hundred stations broadcast on shortwave, however briefly, just from that department. Cajamarca is a special place to me because I visited the region in 1985 during the height of the radio boom and visited over a dozen stations in the towns of Chota, Bambamarca, Cutervo and Celendín and the city of Cajamarca.

Chota is the largest town in the central part of Cajamarca department and played an important role in the development of broadcasting in small provincial towns. It’s about 140 kilometers north of Cajamarca but in between is cold barren Andean altiplano rising to over 4,000 meters elevation. In 1985 the bus ride took twelve hours and we encountered ice storms coming and going.

In 1985 Chota was a sleepy Andean town in a fertile river valley.

Radio Chota was already seven years old when I visited in March 1985. The station only had a medium wave license but also broadcast unlicensed on the out-of-band shortwave frequency of 6296 kHz where it was widely heard by DXers. Later they received a shortwave license and were assigned 4890 kHz but several years passed before they actually switched frequencies. Radio Chota was a success story and is still on the air today. Most of the stations I visited in 1985 were not so lucky.

QSL collection of Don Moore … www.DonMooreDXer.com …

Radio Chota as heard on 6296 kHz in 1982 via On the Shortwaves:

Radio Chota as I heard it in Quito, Ecuador on 4890 kHz in 1997:

Radio Acunta was a more typical broadcaster of the period. The station broadcast irregularly in 1984 and 1985 with a homemade 100-watt transmitter. The station didn’t survive but the transmitter with its crystal-controlled frequency of 5800 kHz was a good starter set. Over the next several years DXers followed its movements around northern Peru as it was sold from one would-be station to another.

This picture with the homemade posterboard signs really captures the transient nature of broadcasting in rural Peru in the 1980s. Radio San Juan de Chota was on 5274 kHz for a few months in late 1984 and early 1985. I doubt they ever had permanent signs made. They did, however, have professionally printed envelopes.

Recording of Radio San Juan de Chota via On the Shortwaves:

Bambamarca is a smaller farming town 20 kilometers south of Chota. It was also home to several shortwave stations over the years. Radio Bambamarca had a short appearance on 5657 kHz in the mid-1980s.

Return to Chota

I always expected to return to the Cajamarca area someday. Finally, in November and December 2017, I revisited all the places I had seen in 1985 and more while researching my historical travelogue Following Ghosts in Northern Peru. A few months later, in May 2018, I returned to the city of Cajamarca and Chota with my DX travel buddies, John Fisher and Karl Forth. Continue reading →

Carlos’ Illustrated Radio Listening Report and Recording of La Union (December 27, 2024)

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Many thanks to SWLing Post contributor and noted political cartoonist Carlos Latuff, who shares an illustrated radio listening report of a recent La Union (Paraguay) broadcast.

Carlos notes:

Part of Radio La Union talk show (in Spanish). News about three men attacked by bees in Encarnacion, Paraguay, leaving one dead. Listened in Porto Alegre, Brazil.

Click here to view on YouTube.

A File Worth Having: Bob’s guide to building an Electrically Small Resonant Loop Antenna for Mediumwave Reception

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Screenshot

This post is short and sweet.

If you click here–Electrically Small Resonant Loop Antenna for Mediumwave Reception (PDF)–you can download a copy of Bob Colegrove’s excellent paper on the Electrically Small Resonant Loop Antenna for Mediumwave Reception.

He has actually built this antenna; it works; and he uses it often. Perhaps you might want to build one for yourself. As an added bonus, Bob is an excellent writer (in my not-so-humble opinion). What’s not to like?

— Jock Elliott, KB2GOM

Carlos’ Illustrated Radio Listening Report and Recording of Radio Buenos Aires (December 12, 2024)

Radio Waves: WNYC to Test Digital AM, RW Letters, and 2025 RTI Audio Calendar

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Radio Waves: Stories Making Waves in the World of Radio

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 Dennis Dura and David Iurescia for the following tips:

WNYC(AM) 820 Set to Test All-Digital AM in December (Radio World)

New York Public Radio and NAB will observe co-channel interference and MA3 performance in an urban setting

820 WNYC(AM) plans to conduct an all-digital MA3 test of AM HD Radio next month.

The test is pending FCC approval, but its owner, New York Public Radio, expects to receive the go-ahead.

NAB is supporting NYPR’s effort, and its Vice President of Advanced Engineering David Layer says all-digital AM is becoming a more viable piece of technology for broadcasters. He cited the increased presence of HD Radio in the marketplace. Fifty-eight percent of new cars in North America ship with the technology, according to Xperi. [Continue reading…]

Letters: Radio Quality, ITU, SDR (Radio World)

Our readers weigh in on recent articles

Here is a sampling from the Radio World reader mailbag.

Is Anyone There?

Ken Deutsch wondered “Why Is Radio So Hard to Listen To?”

He asked, “Is there no one in the building actually listening to the station?” That answer would be no.

Not long ago I went back to help a cluster in Louisville that was missing its chief engineer. It was my first visit in more than 20 years.

When I’d been there last, more than 100 folks worked at six stations in the building. On my return, there were approximately five full-time — the general manager, the operations manager, three sales people. [Continue reading…]

The Sounds of Taiwan (Radio Taiwan International)

Rti has carefully selected the sounds from everyday life in Taiwan, including folk festivals, travel, and the island’s rich cultural and natural heritage over the years. To celebrate Rti’s 97th anniversary, we proudly present our first-ever audio calendar. Let the warmth of Taiwan’s people and the unique local sounds accompany you as you explore the freedom and beauty of this land, welcoming each wonderful day of 2025 together. [Check out the audio calendar at RTI…]