Category Archives: AM

Blackout in Chile: A Reminder of Radio’s Role When All Else Fails

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Many thanks to SWling Post contributor Carlos Latuff, who writes:

Good morning, Thomas. I just translated this article from Chilean radio station “Canal 95”, published on February 26. Original in Spanish here: https://www.canal95.cl/magazine/apagon-redes-sociales-rinden-tributo-radio-pila

After the blackout, social media pays tribute to battery-operated radios

Social media users highlighted the importance of battery-operated radios as the only reliable source of information in emergencies, while critics pointed to the fragility of the current system.

After a large blackout left much of Chile without electricity last Tuesday, millions of people were affected and left without communication. All due the fact that the telecommunications and internet antennas service completely collapsed.

In this scenario, and in the absence of real-time information, social media users began to highlight the importance of having battery-powered radios to access news in emergencies such as, for example, the decision to declare a curfew.

“Will we have to go back to copper wire telephones? Cell phones ‘died’ in the emergency. Explanations are useless in the face of a serious incident. Earthquake, tsunami, flood, or power outage like yesterday. Totally incommunicado. Only the battery-operated radio worked ,” remarked the renowned journalist and radio personality, Sergio Campos.

Many also recalled that this device has been key during earthquakes and other disasters in the country, although there was no shortage of jokes.

“Serious question: does everyone really have a battery-operated radio?” asked one user of the X platform. “It’s always good to have one. My mother-in-law has one and it’s super old, but it works. And the radio too,” joked comedian Luis Slimming.

Although some users admitted not having a functional radio at home, implying that they had not previously considered it necessary due to the outdated technology, other users reinforced the importance of having one of these reliable devices that allow them to stay in touch.

The work of radio stations that continued to operate during the emergency was also highlighted. There was no shortage of criticism of telephone companies and the widespread use of smartphones that do not have integrated FM radio.

“I want to give a round of applause to Chilean radio stations. We would still be going around in circles if it weren’t for the fact that they continued to broadcast and report on what was happening. Every Chilean home should have a battery-operated radio ,” wrote @satoruswft .

It remains to be noted that Chile has historically faced natural events that disrupt basic services, but the current dependence on the Internet and cell phones has created a gap in preparation for blackouts.

So, keep this in mind: a battery-powered radio is still a must-have in an emergency.

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Don Moore’s Photo Album:  Guatemala (Part Three)- Guatemala City Continued

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Many thanks to SWLing Post contributor Don Moore–noted author, traveler, and DXer–for the latest installment of his Photo Album guest post series:

Photo Source: Dennis Sylvester Hurd via Wikimedia Commons

Don Moore’s Photo Album:
Guatemala (Part Three) – Guatemala City continued

by Don Moore

More of Don’s traveling DX stories can be found in his book Tales of a Vagabond DXer [SWLing Post affiliate link]. If you’ve already read his book and enjoyed it, do Don a favor and leave a review on Amazon.

When I started DXing in 1971, and for several decades afterwards, the most widely logged Guatemalan shortwave station by DXers was Radio Cultural on 3300 kHz. It was also known as TGNA, the call letters of that 90-meter-band frequency. The medium wave outlet on 730 kHz was TGN. The station also used 5955 kHz and 9505 kHz, but those frequencies were always harder to hear because of interference from more powerful international broadcasters.

Back then this Evangelical broadcaster was owned and operated by the Central American Mission of Dallas, Texas, but only received a portion of its funding from the CAM. Additional funding came from local donations in Guatemala and another important source was selling time to American Evangelical preachers to air their prerecorded English language religious programs. These programs were broadcast late at night, when propagation into North America and Europe was best, and were always preceded by an English station identification. That made it an easier log for DXers who didn’t understand Spanish.

TGNA was the station I most wanted to visit when I arrived in Guatemala City in June 1983. But Guatemala DX Club members informed me that the station had been temporarily closed down because of “philosophical disagreements” with the government. They were off the air and would remain so for several weeks. I made four more visits to Guatemala City over the next year but somehow never found the time to visit the station. It wasn’t until my visit in December 1987 that I finally stepped inside their front door. That visit became the subject of the first article I wrote for Monitoring Times magazine in June 1988.

Wayne Berger, station manager and chief engineer, and missionary Bob Rice gave us a very long tour of the station. Wayne and Bob had built or rebuilt most of the station’s technical equipment and even some of the infrastructure. On the day we arrived they were welding a broken door back on its hinges. Wayne had built the 3300 kHz transmitter, shown in the next picture, out of spare parts.

Main studio control room at TGNA in 1987.

At the time of my visit, TGNA had two pennants. The larger one was mostly reserved for local listeners. The smaller one was sometimes included with QSLs to lucky DXers.

But neither of those compared with these traditional handmade weavings given by listeners for the station’s 37th anniversary in August, 1987. (I just wish my color photos had survived.)

English ID from Radio Cultural, 3300 kHz, as heard in Pennsylvania 23 November 1979 at 0427 UTC:

Audio Player

Radio Cultural, 3300 kHz, as heard in Michigan 23 March 1989 at 1101 UTC:

Audio Player

Easter in Guatemala

Of all the things I’ve seen in my travels, the Easter processions of Guatemala certainly rank near the top. I am fortunate to have been in Guatemala twice for the holiday, in 1982 and 1984, and I plan a return trip in the next few years. Processions take place all over Guatemala during Easter week, but the most elaborate take place on Easter Thursday and Good Friday in Guatemala City and, especially, in Antigua, the old capital twenty kilometers to the west. There are several processions both days in each city and each procession takes several hours. Continue reading →

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Carlos Visits the Studios of UFRGS Radio

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Visiting the studios of the University Radio of Rio Grande do Sul, Porto Alegre, Brazil

by Carlos Latuff

On the morning of Thursday, February 27, 2025, I visited the studios of the radio station of the Federal University of Rio Grande do Sul (UFRGS in Portuguese) in Porto Alegre, Brazil. Founded in 1950, it’s the first broadcaster in Brazil operated by a university, which currently broadcasts on medium wave (AM) and over the Internet (streaming): https://www.ufrgs.br/radio/ao-vivo/

Headquarters of the UFRGS radio studios in Porto Alegre, Brazil.

The programming focuses mainly on classical music, but it also has programs of other musical styles. Despite the technical, bureaucratic and financial difficulties (a typical scenario of state radio stations in Brazil), the UFRGS Radio has been operating thanks to the efforts of its team. One of the things that catches my attention at this station is the news bulletin, broadcast on weekdays at 12:00 p.m. local time, presented by Mrs. Claudia Rocca.

News bulletin from UFRGS Radio, voiced by Mrs. Cláudia Rocca.

The bulletin is 10 minutes long and brings local, national and international news, some of which are suitable for my already traditional illustrated radio listening.

According to the station’s director, Mr. Claudio Roberto Dornelles Remião, the UFRGS radio station, like most AM radio stations in Brazil, will migrate to FM, but there’s still no set deadline.

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Beyond DXing: Analyzing Medium Wave Propagation During the 2023 Annular Eclipse

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The following article dives into medium wave (MW) radio propagation during the 2023 annular solar eclipse, building upon insights from the 2017 total solar eclipse when DXers made broadband radio recordings of the whole MW band for the first time. Unlike that previous study, the 2023 research took a methodical approach, with standardized data collection, stable receivers, and GPS-synchronized frequency locking. Thirteen radio enthusiasts across North America and Europe contributed to the study, capturing 10 Terabytes of SDR data. Using Carrier Sleuth software, researchers pinpointed key signal strength variations, with some regions experiencing remarkable boosts in signal during the eclipse. These findings highlight how eclipse-induced propagation effects are not the same as those seen during typical sunrise and sunset transitions. The study opens doors for further exploration into whether these effects are symmetrical and how they might relate to ionospheric thinning along specific signal paths.  The article ends by asking assistance from DXers to help ID enhanced signals in the 2023 eclipse data sets.  

Medium Wave Monitoring During the 2023 Annular Solar Eclipse—Not Just About DXing

By Nick Hall-Patch, VE7DXR

Background        

The 14 October 2023 annular solar eclipse was the first one to cross the continental United States since the total eclipse of 17 August 2017. From a DXing standpoint, 2017 was the first eclipse in which there was widespread use of software defined radios (SDRs) to record the entire medium wave (MW) band throughout the duration of the eclipse.  Therefore, it was possible to study eclipse receptions after the fact rather more than had been the case during earlier ones. Several IRCA members recorded the 2017 eclipse on their SDRs, and in the months after the eclipse, data files from several locations were examined. It was therefore possible to evaluate the varying signal strength of KSL-1160’s carrier from four different locations in western America, all from outside the path of totality, and to speculate upon the differences in the responses at each site.

That study of KSL’s strength variations during the eclipse led to a presentation at the St. Louis IRCA/NRC convention in 2018, and eventually to an IRCA Technical column (now IRCA Reprint G-096 at  http://dxer.ca/images/stories/2019/irca-reprint-index.pdf) which proved to be of interest to HamSCI, an amateur radio citizen science group that had already been using amateur radio communications as a way to study that eclipse’s effects upon the ionosphere. A version of the article appeared on HamSCI’s website and the SDR files referenced by the article were also hosted by the HamSCI community on zenodo.org, along with SDR data from three further locations in eastern America. (Go to zenodo.org, and search on the phrase “Solar Eclipse 2017 recordings” to examine this data for yourself.)   Zenodo is a long-term open repository for scholarly work, and these data sets have since been downloaded hundreds of times.

Why would these 2017 SDR files have been of interest to an organization studying radio wave propagation?  Unlike the short duration communications found on the amateur radio bands, medium wave (MW) AM broadcasters, assigned between 525 and 1705kHz, provide continuous signals, many for 24 hours a day. Their carrier frequencies are like steady RF beacons.  Any changes in that beacon’s amplitude or frequency at a receiver are likely to have been caused by changes in the path between transmitter and receiver. By using suitable hardware and software, either monitoring a single frequency or the entire medium wave broadcast band using SDRs, the resulting files can allow us to characterize the propagation induced changes that these carriers undergo over time, including variations in signal strength and apparent shifts or spreading in the frequency of each carrier.   During a solar eclipse, the brief period of darkness along the path of the eclipse can allow AM broadcasters’ signals to temporarily travel much further than they would normally in the daytime, and it is possible to study variations that occur even more quickly than those occurring daily during sunrise and sunset.

Preparation for the 2023 Solar Eclipse

From a DXing standpoint, the 2017 eclipse SDR files were more than functional, but a closer examination revealed gaps in the data, changes of antennas when it suited the DXer, and receivers that had not been properly warmed up, resulting in recorded carriers that appeared to be drifting.  From the standpoint of a scientist, this was “found data” requiring judicious handling and compensation.  In addition, the data had been transferred many months after the recording had taken place, and sometimes it was no longer clear how the receivers and antennas had been set up for the recording.

Nearly a year before the 2023 eclipse, HamSCI had decided that it would be interested in examining more MW SDR data, but this time asking that the recording of the data be approached in a more professional fashion.  In other words, participating DXers would be asked to think a bit more like scientists for the duration of the recordings.  Making recorded IQ files of optimum use to propagation researchers would include the following:

  • Documenting receiver, software and antenna used, with as many details as possible.
  • Not making changes in receiver or antenna configuration during the recording period; if absolutely necessary, recording that change in detail, especially the time that it occurred.
  • Warming up the receiver for several hours before recording in order to minimize apparent carrier drift in recorded signals.  Better yet, encouraging participants to use SDRs that were locked to a frequency standard such as the Bodnar GPS reference clock, because a frequency locked SDR’s data would display frequencies with stability and accuracy, and allow characterization of any carrier Doppler shifts.
  • Making sure that timestamps in their recorded data were as accurate as possible, at a minimum setting the computer clock accurately immediately before recording, and preferably to use a network time protocol (NTP) time client on the computer that would be recording the SDR IQ files.
  • Starting recording well before maximum totality in their area, until well after that time; one hour before the start of the partial eclipse to one hour after the end of the partial eclipse were suggested as a minimum.
  • If possible, making additional SDR recordings of, for example, the period from two hours before and after sunset and sunrise on the day of the eclipse, and also making a reference recording of the eclipse time period on another day.

Figure 1 shows the path of the 2023 eclipse and the times of maximum obscuration.  Efforts were made to involve monitors in both North and South America, and in the end, 13 participants were involved in the experiment, using 14 sites in Canada, the USA, Mexico and Portugal.

Figure 1

  • 12 sites also included data from local sunrise (LSR) and/or local sunset (LSS)
  • 12 sites also recorded data from the same time as the eclipse period on another date in order to provide a reference of a normal day’s reception conditions
  • 6 sites produced data using an SDR locked to a frequency standard that was disciplined using GPS signals. Three of the remaining sites included a signal from a frequency standard in their data recording.
  • 10 sites recorded using computers that had their clocks updated using Network Time Protocol (NTP); others set computer time manually

About 10 Terabytes of SDR recordings were submitted for analysis, which is one heck of a lot to poke through in order to find signals fading up and down for a few minutes during the course of the eclipse. Fortunately, it was possible to pre-process all of the files using Carrier Sleuth software which allowed visualization of hours of data at a time from each MW channel, all available to 0.1Hz resolution over an 80Hz span centered on each broadcast channel.  It was then a fairly quick process to scan through each of the 117 channels of the AM broadcast band for each data set, searching for unusual carrier enhancements appearing during the eclipse time period.

An example is shown in Figure 2, portraying 1650 kHz as logged during eclipse enhancement in Phoenix, AZ by Burke Baumann KF7NP. The thin lines representing various carriers are represented in “hotter” colors when signal strength increases.

Figure 2

Because Carrier Sleuth can rapidly generate a chart for signal strength vs. time for each individual carrier, it was decided arbitrarily that a carrier that increased in strength by at least 10dB during the duration of the eclipse at that site would be deemed to have been influenced by the passage of the moon’s shadow.  By that metric, six sites indeed reported that during the eclipse, different broadcast signals appeared from those normally received in the daytime.  However, other sites did not, or received only a few traces of carriers during the eclipse period.

Figure 3 shows the various sites that submitted SDR data, indicated by pale blue circles, and within each circle is the number of AM broadcast band channels on which eclipse effects were noted, even if it was just a carrier.

Figure 3

From Figure 3, it can be seen that locations in Canada’s west and in the south and west of the USA were likely to have been influenced most by the passage of the eclipse. In contrast, it appears that those who were in locations of less than 50% of totality were unlikely to have seen much effect from the passage of the eclipse. Continue reading →

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Don Moore’s Photo Album:  Guatemala (Part Two) – Guatemala City

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Many thanks to SWLing Post contributor Don Moore–noted author, traveler, and DXer–for the latest installment of his Photo Album guest post series:

Image Source: Wikimedia Commons

Don Moore’s Photo Album:  Guatemala (Part Two) – Guatemala City

by Don Moore

More of Don’s traveling DX stories can be found in his book Tales of a Vagabond DXer [SWLing Post affiliate link]. If you’ve already read his book and enjoyed it, do Don a favor and leave a review on Amazon.

Guatemala City, the country’s capital, is the political, economic, and social hub of the country. The next largest city, Quetzaltenango, is less than a fifth as big. Guatemala City also forms a pivot point dividing the country. The departments to the west and the Verapaz region to the north are heavily indigenous. Quiché department is named after the country’s largest Mayan group. The Pacific departments to the south and those to the east are mostly populated by Spanish-speaking ladinos, which is what mestizos of mixed Spanish and indigenous heritage are called in Guatemala. It’s the ladinos and Guatemala’s small European-descended upper class who rule the country. Although the Mayans and a few smaller groups represent half of Guatemala’s population, the country has never had an indigenous president. That’s not where the power lies.

While I was working in Honduras, all of my visits to Guatemala included a few days in Guatemala City. It wouldn’t make anyone’s lists of Latin America’s best capitals but I always enjoyed returning. It felt like a city. Honduras’ capital of Tegucigalpa felt like an overgrown small town.

Guatemala City had a very diverse radio scene with stations programming for all the segments of the population. You could tune in everything from Guatemalan marimba music to English-language rock to Spanish-language romantic pop to Mexican ranchera to Argentine tango. There was even a commercial classical music station on medium wave. Several of the stations – Radio Nuevo Mundo comes to mind – had very professional news departments. And three of Guatemala City’s radio stations broadcast on shortwave.

But for me the best part of visiting Guatemala City wasn’t the shopping or the museums or even visiting the radio stations. It was getting to see my friends in the Guatemala DX Club.

Guatemala DX Club

In early 1983 I connected with the Guatemala DX Club through Radio Netherlands’ Spanish language DX program, Radio Enlace.  I first got together with them on my second visit to Guatemala in June 1983 and then made a point of visiting them every time I came to the city. The GDXC had several dozen members, mostly in Guatemala City. Only about eight or ten regularly participated in club events and those are the ones I met. The club had occasional meetings, sometimes organized visits to radio stations, and published an annual newsletter. They also produced a weekly fifteen-minute DX program on La Voz de Guatemala.

This photo was taken during my last visit in December 1987. In the back row are Carlos Zipfel Valencia, Jorge Luis Álvarez, and Edgar Oliva. Me and Ralf Gruner are seated in front.

Edgar was an official monitor for Deutsche Welle and had a beautiful huge Grundig receiver that the station had gifted to him. It had been sent by diplomatic pouch to the West German embassy where he had picked it up in person.

Carlos’ father, Carlos Zipfel y García, was a well-known Guatemalan writer but Carlos was more interested in the spoken word of radio. After getting a communications degree he received professional training through programs run by Radio Netherlands and Deutsche Welle and pursued a career in broadcast journalism and management. At different times he’s served as a producer for La Voz de Guatemala, director of Radio Universidad de San Carlos, and in various roles for several public and non-government organizations such as the Federation of Guatemalan Radio Schools.

I’ve always liked the GDXC pennant. It was intentionally designed to point left so that it would easily fit on the wall between the usual right-pointing radio station pennants. Only a DXer would think of doing that! The design features Guatemala’s national bird, the quetzal, which is known for its long tail feathers.

La Voz de Guatemala

During my first visit with the club, Carlos used his day off to take me to visit the radio station he was working at plus several more medium wave and FM stations. He already had many professional contacts so I had some very memorable station tours. Carlos also used his press credentials to get me a private tour of part of the Palacio Verde, or presidential palace.

The station I was most interested in seeing was the official government radio station, TGW La Voz de Guatemala, also sometimes called Radio Nacional de Guatemala. I had a very long visit there as Carlos, of course, had connections. It was he who produced the club’s weekly DX program on TGW.

The Estudio Maya was a spacious room where live marimba music concerts were broadcast each week. The station even had its own handmade marimba. The use of the name Estudio Maya is interesting. Guatemala embraces the historical image and importance of the Mayans while at the same time ignoring the present-day Mayan population. Half of Guatemala’s population speak Mayan languages but the national radio station only broadcast in Spanish.

Visiting radio stations usually includes collecting souvenirs and TGW didn’t disappoint. Here are several items from the station’s 50th anniversary in 1980. I also picked up several QSLs signed and sealed not just by the head station producer but also by Carlos on behalf of the Guatemala DX Club.

TGW La Voz de Guatemala, 640 kHz, as recorded in Guatemala City in June 1983:

Audio Player

A Musical Interlude

The marimba is Guatemala’s national musical instrument and if you ever heard one of Guatemala’s shortwave stations you surely heard the music. Like the banjo, the marimba is an instrument that always sounds happy. It’s impossible to play a sad song on one. The instrument is like a xylophone but is made of wood. Although smaller ones do exist, a true marimba requires seven musicians playing in unison. A live concert is an amazing sight. Continue reading →

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AM Band RF Noise Study

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Photo by Brock Wegner on Unsplash

Many thanks to SWLing Post contributor, Dennis Dura, who shares the following article from Radio World:

NRSC Releases Details of AM Band RF Noise Study (Radio World)

Noise levels remained consistent throughout different environments, even in downtown Baltimore

The National Radio Systems Committee’s AM Improvement Working Group has published a study examining the effects of RF noise on AM radio reception in cars.

Radio World readers will find the study’s scientific detail of interest. Noteworthy was how RF noise on the road often did not vary amongst the diverse environments sampled. Overcoming downtown building signal degradation was more of a concern, according to the study’s authors. Additionally, the study found field strength projections of AM signals to often not be reflective of contour predictions.

The group’s study intended to provide a better understanding of how AM radio reception is affected by RF signal strength and noise in a range of roadway environments. The authors also provided some suggestions to overcome signal loss. [Continue reading…]

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