Category Archives: Mediumwave

Radio Waves: Radio Tirana’s Global Communist Voice, Sounds of Community Radio, Morse Code Phishing, and the Mission of Vatican Radio

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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 David Shannon, Dennis Dura, and David Iurescia for the following tips:

Sources on Cold War Radio, Paradoxes, Maoism, and Noise (Wilson Center)

Radio Tirana emerged as a global Communist voice in the 1970s, reaching Brazilian guerillas in Araguaia, Maoist factions across Asia, Africa, and Latin America, and many other listeners around the world. Elidor Mëhilli explains how this came to be.

“Dear Radio Tirana,” the letter begins, “here in the Alps we can hear you well, and we are especially fond of your propaganda directed at the Italian Communist Party.” The letter is dated April 12, 1976 but its Italian authors are not named. After a final greeting “Viva Mao e Viva Stalin,” they have simply signed off “a group of true Communists.”[i]

Two months earlier, in Entroncamento, Portugal, someone has penned a letter to the same station. “Camaradas,” his note begins, “I am a worker (a porter) who listens regularly to your Portuguese-language broadcasts.” The letter then proceeds with complaints about the fate of Communism in Portugal, with questions about Albania’s foreign policy, about why Radio Tirana spoke so infrequently about Portugal, about sports, about whether a trip to the Balkans might be possible.[ii]

By March, in Arequipa, Peru, a thirty-year-old places the recipient’s address on a small envelope: Señor Director, Radio Tirana, Albania.

He is among early Peruvian intellectuals who have been drawn to Mao Zedong’s ideas. Having completed a thesis on the topic, he is on his way to becoming a professor within a few years. “Unfortunately, I have to tell you that it’s been over a year that I do not receive your broadcasts,” he writes, “I think that it might due to the interference of the imperialist Yankees or perhaps the Soviet social-imperialists.”[iii]

Once a modest station, Radio Tirana had become a global Communist voice by the 1970s, reaching Brazilian guerillas in Araguaia, teeny-tiny Maoist factions across Asia, Africa, and Latin America, far-flung dots scattered across oceans and seas. This turned the station into a kind “of superpower of its kind” as author Ardian Vehbiu has put it. Officials embraced this role, broadcasting in numerous languages—English, Arabic, French, Italian, Greek, Portuguese, German, Indonesian—and beaming anti-capitalist and anti-Soviet messages day after day.[…]

World Wide Waves: The Sounds of Community Radio (BBC World Service)

We think we live in a digital age, but only half the world is currently online. Across the globe, small radio stations bind remote communities, play a dazzling array of music, educate, entertain and empower people to make change. Cameroon’s Radio Taboo, in a remote rainforest village 100 miles off the grid, relies on solar power; its journalists and engineers are all local men and women, and some of its audience listen on wind-up radios. In Tamil Nadu, Kadal Osai (“the sound of the ocean”) broadcasts to the local fishing community about weather, fishing techniques—and climate change. In Bolivia, Radio Nacional de Huanuni is one of the last remaining stations founded in the 1950s to organise mostly indigenous tin miners against successive dictatorships; its transmitters are still protected by fortified walls.

For World Radio Day, we visit community stations around the globe and celebrate the enduring power, possibilities and pleasures of the airwaves.

This program will be available shortly after broadcast on Feb 14, 2021. Click here for details.

New phishing attack uses Morse code to hide malicious URLs (Bleeping Computer)

A new targeted phishing campaign includes the novel obfuscation technique of using Morse code to hide malicious URLs in an email attachment.

Samuel Morse and Alfred Vail invented morse code as a way of transmitting messages across telegraph wire. When using Morse code, each letter and number is encoded as a series of dots (short sound) and dashes (long sound).

Starting last week, a threat actor began utilizing Morse code to hide malicious URLs in their phishing form to bypass secure mail gateways and mail filters.

BleepingComputer could not find any references to Morse code being used in phishing attacks in the past, making this a novel obfuscation technique

The novel Morse code phishing attack
After first learning of this attack from a post on Reddit, BleepingComputer was able to find numerous samples of the targeted attack uploaded to VirusTotal since February 2nd, 2021.

The phishing attack starts with an email pretending to be an invoice for the company with a mail subject like ‘Revenue_payment_invoice February_Wednesday 02/03/2021.'[…]

Father Lombardi: Mission of Vatican Radio in service of the Pope (Vatican News)

We reproduce excerpts from an article written on the 90th anniversary by the former Director of Vatican Radio, which were published in the latest issue of La Civiltà Cattolica.

By Fr Federico Lombardi, SJ

On 12 February 2021 it will be exactly 90 years since Pope Pius XI inaugurated the new Vatican Radio Station – built at his request by Guglielmo Marconi and entrusted to the care of Jesuit Father Giuseppe Gianfranceschi as its first director. The “mission of Vatican Radio was clear from the beginning: to be an instrument at the service of the Pope for his ministry of proclaiming the Gospel in the world and guiding the universal community of the Catholic Church. This mission has been preserved over time and has been reaffirmed several times by the Popes, guaranteeing a strong identity of the institution. […]

The voice of the Pope
Vatican Radio […] was founded in 1931, in the context of the rapid establishment of the new Vatican City State […]. The radio station built by Marconi was at the forefront of the technology of the time, and was able to provide telegraphic and radio service completely independently from Italy. Thanks to short-wave technology, in an “ether” not yet overcrowded with countless transmissions, it was possible to be heard on other continents with a rather low power. At the beginning of its existence, Vatican Radio was the instrument thanks to which the Catholics of the world could hear the voice of the Pope directly for the first time. […]

The 1930s were years of the power of totalitarianism. Pius XI’s positions were courageous and, in the thickening of the storm, he looked to the Church with confidence. The demand for broadcasts in different languages to guide and support the faithful in European countries grew rapidly. Father Filippo Soccorsi, appointed to lead the Radio in 1934 (at 34 years old!), after the untimely death of Fr. Gianfranceschi, not only dedicated himself to improving the technical structures — such as the new antenna towering over the Vatican gardens, known as “The Pope’s Finger” — but promptly grasped the expectation to make the Radio grow also in the content of its programming. Thus, in 1936, the Vatican Broadcasting Corporation was accepted into the International Broadcasting Union with a recognition of its special nature, which authorised it to carry out radio activities without any geographical limitations. Because of the limited means available, Fr Soccorsi asked for the collaboration of Jesuit brethren from various countries for the editing and presentation of the texts. The German-language broadcasts were particularly important.

In the tragedy of war: for peace and solidarity with the suffering
[…] On the eve of the war, in 1939, there were regular broadcasts in Italian, French, English, German, Spanish, Portuguese, Polish, Ukrainian, and Lithuanian, and the station was able to be a point of reference for the Church in the immense tragedy, playing its role of denouncing violence, supporting victims and members of the resistance, and encouraging hope. The “Radio-messages” of Pius XII in wartime, eagerly awaited and listened to with great attention throughout Europe, remain famous. His was the loudest and most authoritative voice rising above the warring parties in those terrible years, calling for justice and peace.

During the war, however, Vatican Radio became famous for another service: it was in fact a fundamental instrument of the great commitment desired by Pius XII with the “Information Office of the Secretariat of State,” set up in 1939 to track down missing civilians and soldiers and prisoners; to provide information to their families and, if possible, to re-establish among them at least a link of greeting and remembrance. […]

Vatican Radio devoted specific broadcasts to requesting news about the missing and broadcasting short messages from the families to the prisoners, whose names were slowly spelled out by the “metallic” voice of the speakers. These broadcasts reached 70 hours per week, with peaks of 12-13 hours per day. Between 1940 and 1946, a total of 1,240,728 messages were broadcast in 12,105 hours of actual transmission time. In some cases, the transmissions were broadcast over loudspeakers in prison camps. The testimonies of gratitude for this service were numerous and moving. This is one of the most beautiful pages in the history of Vatican Radio.

A voice for the “Church of Silence”
With the end of the war, Vatican Radio accompanied with its broadcasts the climate of moral and spiritual reconstruction of the countries devastated by the conflict, while preparations were in full swing for the great Holy Year of 1950, a time of renewed vitality of the Church.

But in the meantime, most of Eastern Europe fell under the oppression of the communist regimes, and the Catholic Church became the object of harsh persecution in many countries. This was an historic challenge for Vatican Radio, which was practically the only way through which the faithful could nurture their bond with the Pope and the universal Church and receive support for their faith. Even with limited resources, programmes in the languages of Eastern European countries became more numerous and were given more airtime. At the end of the 1940s, the programme in Polish — which together with Italian, English, French, Spanish and German had always been one of the main languages of transmission — was joined by those in Czech, Slovak, Hungarian, Lithuanian, Latvian, Russian, Croatian, Slovenian, Ukrainian, Romanian, Bulgarian, Belarusian and, shortly afterwards, Albanian. For decades, throughout the time of oppression, the broadcasts of Vatican Radio offered a regular and sure appointment for the faithful, religious, priests and bishops deprived of the freedom to express and live their faith.

There would be countless stories to tell about those years. In certain countries and in certain periods of the harshest persecution, listening to Vatican Radio was absolutely forbidden and seriously dangerous: it could be the cause of serious penalties, up to imprisonment and even — in some cases — the death sentence. For some languages, such as Polish or Slovak, the audience was high, while for others, where Catholics were a minority, there were not many listeners. But the principle that guided the fathers of the Radio, according to the Pope’s intention, was not the vastness of the audience, but the situation of need of the listeners. That is why the languages of broadcasting to Eastern countries have always represented more than half of the languages used by Vatican Radio. When, after many years, the walls fell, the gratitude of the faithful and the people could finally express itself in moving forms, such as the more than 40,000 letters that arrived at the Ukrainian Section in the first year after the fall of the Soviet regime, or the bestowal of the award of the Albanian State for the work of Vatican Radio. […]

Communication for communion
In 1970 the editorial offices and studios of Vatican Radio moved to Palazzo Pio, in front of Castel Sant’Angelo, providing adequate space in what would become the main headquarters of the station for decades. In 1973 Father Roberto Tucci […] succeeded Father Martegani in the general direction. We were on the eve of the Holy Year 1975 and the Radio was completely mobilised. It was not only a matter of broadcasting live the great papal celebrations, audiences and events, and of giving adequate information in all languages so that the universal Church felt involved, but also of providing a service for pilgrims arriving in Rome from all over the world. […]

Pasquale Borgomeo, who would become a dynamic and creative director of programmes; and Father Félix Juan Cabasés, in charge of the “Central Editorial Office,” later the “Documentation Service”: The former would greatly cultivate the valuable international relations of the station, in particular with the European Broadcasting Union (EBU); the latter would leave a lasting mark in the organisation of documentation and editorial programming. […]

Vatican Radio thus reached maturity, with increasing professional and journalistic quality, which makes it not only the beating heart of daily communication in the universal Church — “communication for communion”, as the Council hoped — but also an active protagonist in the wider world of Catholic and lay communication in the life of the Church.[…]

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Guest Post: Using Carrier Sleuth to Find the Fine Details of DX

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Many thanks to SWLing Post contributor, Nick Hall-Patch, for sharing the following guest post:

Using Carrier Sleuth to Find the Fine Details of DX

by Nick Hall-Patch

Introduction 

Medium wave DXers are not all technical experts, but most of us understand that the amplitude modulated signals that we listen to are defined by a strong carrier frequency, surrounded on either side by a band of mirror image sideband frequencies, containing the audio information in the broadcast.

Most DXers’ traditional  experience of carriers has been in using the BFO of a receiver, using USB or LSB mode, and hearing the  decreasing audio tone approaching “zero beat” of the receiver’s internal carrier compared with the DX’s carrier frequency as one tuned past it.  This was often used as a way of detecting that a signal was on the channel, but otherwise wasn’t strong enough to deliver audio.  Subaudible heterodynes,  regular pulsations imposed on the received audio from a DX station, could indicate that there was a second station hiding there, with a slightly different carrier frequency,  And, complex pulsations, or even outright low-pitched tones could indicate three or more stations potentially available on a single channel.

With the advent of software defined radio (SDR) within the last 10 years or so, the DXer has also been able to see a graphical representation of the frequency spectrum of the carrier and its associated sidebands.  (Figure 1)  Note that the carrier usually remains stable in amplitude and frequency, unless there are variations introduced by propagation, but that the sidebands are extremely variable.

Figure 1

Figure 2

In addition, by looking at a finer resolution of the SDR’s waterfall display, one might see additional carriers on a channel that are producing heterodynes (audible or sub-audible) in the received audio (Figure 2).  Generally speaking, a DX signal with a stronger carrier will be more likely to produce readable audio, although there are exceptions to that rule.

Initially, DXers wanted to discover the exact frequency of their DX, accurate to the nearest Hertz.  Although only a small group of enthusiasts were interested, they have produced a number of IRCA Reprints (https://www.ircaonline.org and click the “Free IRCA Reprints” button) over the years under the topic of “precision frequency measurement” (e.g. T-005, T-027, T-031, T-079, T-090) describing their use of some reasonably sophisticated equipment for the day, such as frequency counters.

So, why would this information be at all important?  In effect, the knowledge of the exact frequency of a carrier was used to provide a fingerprint for a specific radio station.    Usually, this detail was used by DXers who were trying to track down new DX, and wanted to determine whether a noisy signal was actually something that had been heard before, so would not waste any more time with it.  The process of finding this exact frequency has since been made much easier by being able to view the carrier graphically in SDR software, assuming that the SDR has been calibrated before being used to listen to and record the DX.   Playing back the recorded files will also contain the details of the exact frequency observed at the time of recording.  And, because the exact frequency of DX has become much easier to determine using SDRs, more and more DXers seem to be using this technique.

At present, Jaguar software for Perseus is the one being used by many to determine frequency resolution down to 0.1Hz, both in receiving and in playback.   But, if you have recorded SDR files from hardware other than Perseus, it is possible to get that resolution also, using software called Carrier Sleuth, from Black Cat Systems, available for both Mac and Windows, at a cost of US$20.

This software will presently take as input, sets of RF I/Q files generated by SpectraVue, SdrDx, Perseus (which includes files recorded by Jaguar), Studio One / SDRUno, Elad, SDR Console, and HDSDR.  It then outputs a single file with a .fft extension, that provides the user with a set of waterfalls, similar to those displayed by SDR programs.  The user decides ahead of time which frequency or set of frequencies (including all 9kHz or all 10kHz channels) will be output, and these will be displayed as individual waterfalls. one for each chosen frequency.  These waterfalls can be stepped through from low frequency to high frequency, or chosen individually from a drop down menu.

Let’s start by looking at a couple of output waterfalls and work out what can be done with them, then step back to find out how to generate them, and what other data is available from them.  Finally, we’ll do a quick comparison with two other programs that can produce similar output, and discuss the limitations in all three programs.

Example outputs from Carrier Sleuth

An example showing the original intent of Carrier Sleuth, determining precise carrier frequencies, is shown in Figure 3, a waterfall from 1287kHz on the morning of 28 November 2020.  At 1524UT, a woman mentions “HBC” and “Hokkaido” in the original recording, so, it’s JOHR, Sapporo.   Although there are a number of vertical lines representing carriers in this graphic, only one has a strong coloration, indicating at least 25dB more strength than any other carrier at the time of the ID, and about 50dB more than the background level.     The absolute values of time, signal strength, and carrier frequency precise to 0.1Hz, can be found by mousing over the desired point in the waterfall and then reading the numbers in the upper right corner of the display, (encircled in Figure 3).  In this case, the receiver’s reference oscillator had been locked to an accurate 10MHz clock, disciplined by GPS, so the frequency indicated in the software is not just precise, but should also be accurate.   Similar accuracy could be obtainable by the traditional method of calibrating the SDR to WWV on 10 or 15MHz.

Carrier Sleuth indicates 1287.0002kHz, within 0.1Hz of that observed by a contributor to the MWoffsets list about 7 weeks earlier (https://www.mwlist.org/mwoffset.php?khz=1287). If you look closely, there is a slight wobble on the frequency, but the display is precise enough that it can indicate that, despite the wobble, JOHR does not wander away from that frequency of 1287.0002kHz.

Figure 3

But let’s face it, tracking carriers to such accuracy is a specialist interest (though admittedly, the medium wave DXing hobby is full of specialist interests, and this one is becoming more mainstream, at least among Jaguar users).  However, if I played back a file from another morning, and found a strong carrier on a slightly different frequency from 1287.0002kHz, it might be an indication that some new Chinese DX was turning up, and that the recorded files would be worth a closer listen at that particular time.

Figure 4

In fact, I’ve found Carrier Sleuth to be useful in digging out long haul DX after it’s been recorded, as both trans-Arctic and trans-Pacific DX at my location in western Canada can be spotty at the best of times.  This means spotty as in a “zero to zero in 60 seconds” sort of spotty, because a signal can literally fade up 10 or 15dB to a readable level in 20 seconds, perhaps with identifiable material, then disappear just as quickly.   My best example so far this season was on 1593kHz, early in the UTC day of 16 November 2020, when a Romanian station on that channel paid a brief visit to my receiver in western Canada.  An initial inkling of that showed up in a Carrier Sleuth waterfall, a blotch of dark red at 0358UT, and indicated by the yellow arrow in Figure 4; that caused me to go back to the recorded SDR files that had generated these traces.

The dark blotch indicates a 10dB rise and fall in signal strength including about 60 seconds of rough audio, which turned out to be the choral version of the Romanian national anthem (RCluj1593.wav).  That one carrier and another one both started up at 0350UT, the listed sign-on time for Radio Cluj, which does indeed begin the broadcast day with that choral anthem.   Which one of the Radio Cluj transmitters was heard is still an open question, due to the lack of carrier sleuths (computerized or otherwise) on the ground in Romania,  but the more powerful one listed is a mere 15kw, so I will take either.

Finally, for those who have interest in radio propagation, the Carrier Sleuth displays can reveal some odd anomalies, for example, Figure 5 which displays both Radio Taiwan International (near 1557.000kHz on 28 November, but varies from day to day), and CNR2 (1557.004kHz)  carriers as local sunrise at 1542UT approached in Victoria, BC.

Figure 5

The diffuseness of the carriers is striking, as is their tendency to shift higher in frequency at local sunrise.  This doesn’t seem to be some strangeness in the original SDR recording, as there appear to be unaffected weak carriers on the channel.  For comparison, Figure 3 shows the same recorded time and date, but on 1287kHz, and JOHR’s carrier is pretty stable, but there are others on that channel that show the shift higher in frequency around local sunrise.  As one goes lower in frequency, these shifts became smaller and less common on each 9kHz channel, and disappear below about 1000kHz.    On later mornings, however, the shifts could be found right down to the bottom of the MW band.  Certainly, these observations are food for further thought.

Many of the parameters in Carrier Sleuth are adjustable by the user, for example, the sliders at the top of the screen can allow adjustment of the color palette to be more revealing of differences in signal strength.   The passband shown is also easily changed, and in fact, setting  the passband width to 400Hz, instead of my usual 50Hz , and creating another run of the program on 1557kHz, shows very clearly the sidebands of the “the Rumbler”, a possible jammer on the channel  (Figure 6).  Incidentally, a lot of the traces around 1557.000kHz in Figure 5 may well be part of “the Rumbler” signal as well, as filtering of the audio doesn’t seem to improve readability on the channel.

Although the examples here are taken from DXing overseas signals from western Canada, there is no reason why similar techniques may  not be applied to domestic DXing, particularly during the daytime, when signals can be weak, but can fade up unpredictable for brief periods.

Figure 6

How to create these waterfall displays in Carrier Sleuth?

So, how can you get these displays for yourself?  A “try before you buy” version of the program is available at http://blackcatsystems.com/software/medium_wave_carrier_display_app.html  and both the website and the program itself contain a quite detailed set of instructions.    However, the 25 cent tour can be summarized this way:

You start with a group of supported SDR data files, previously recorded, and use “Open I/Q data files” in the File drop down menu. Figure 7 shows the window that will open to allow you to choose any number of the files from your stored SDR files, by clicking the Add Files button  circled in red.  Then choose one of the options inside the green circle in Figure 7.  They are explained in more detail in the help write up; note that the “Custom Channel” can be specified to considerably more precision than just integer kHz values, e.g. 1205.952     The rest of the settings you will probably adapt to your needs as you gain experience.   Finally, set an output file name using the Set Output File button, and hit the “Process” button at the bottom of the window. There are a couple of colored bars in the upper right hand corner of the display that indicate progress, along with number of seconds left, although these are not always visible.

Figure 7

The generation of these waterfalls takes time.   A computer with a faster CPU and more memory will speed things up.  There is, however, an important limitation of the program.  It is specified for 32-bit systems, and although it will run with no problem on 64-bit systems, individual input I/Q files are therefore restricted to 2GB or less.   Many SDR users now choose to create larger files than this, and Carrier Sleuth will not handle them.  Another possible limitation can occur when processing 32M FFTs, which are useful for delivering very fine frequency resolution of the carriers displayed.   The program really requires in excess of 4GB of memory to handle the computation needed to deliver this fine a scale.  Unfortunately, both the 2GB file size limitation and insufficient memory limitation deliver generic error messages, followed by program termination, which leaves the inexperienced user none the wiser about the true problem.

This might be a good place for a word about FFT size and Resolution Bandwidth (RBW).  The FFT is a mathematical computation that takes as its input the samples of digital data that an SDR generates (or those samples that  have been saved in recorded files), and generates a set of “bins”, which are individual numbers representing signal strength at a defined number of consecutive frequencies spaced across the full bandwidth being monitored by the SDR. You could think of these bins as a series of tiny consecutive RF filters, spread across the band, each delivering its own signal strength.   As we are trying to look at fine scale differences in frequency when using a program like Carrier Sleuth, it is important that these little “RF filters”, or bins, each have a very narrow bandwidth.  This value is called “Resolution Band Width” (RBW), and preferably should be a fraction of a Hertz to get displays such as those shown in Figures 3 through 5.

The “FFT Length” is the number of bins that the FFT display contains, and is equal to the number of I/Q samples (either from the SDR or recorded file) that are used for the input to its computation.  The relationship between FFT Length, the bandwidth of the SDR or of the original recorded I/Q file, and the RBW is fairly simple:

Because the MW DXer is usually looking at data with 1MHz or more bandwidth, this equation tells us that to get a smaller than 1Hz RBW, we will need to have an FFT length of well over  one million bins, so it would be wise to use an FFT length at least 8M(illion).   If you are looking at a recorded file that is from an SDR using a lower bandwidth, then a lower FFT length will do the job to get a smaller RBW.

A downside of using a long FFT length is that the time resolution of the FFT becomes poorer, resulting in a display in Carrier Sleuth that will appear to be compressed from top to bottom compared with what was seen when recording the SDR file, and with correspondingly less response to fast changes in signal strength.   However, using a 16M FFT Length on a recording of the MW band results in a time resolution of about 12 seconds, so it should not be a deal breaker for most.

Producing signal strength plots 

A further specialist activity for some DXers is recording signal strength on specific channels, and then displaying the progress of signal strength versus time, often to indicate when openings have occurred in the past  (say, at transmitter sunset),  and perhaps allowing one to predict such openings in the future.    But, the world has come a long way from the noting down of S-meter readings at regular time intervals, both in deriving signal strength and in plotting the results.  Read on for an example.

Figure 8

Carrier Sleuth recently added the capability of creating files containing signal strength versus time for specified frequencies, and, depending on the size of RBW, to deliver that signal strength as observed in a passband as narrow as 0.05Hz, or as wide as 10Hz.   The program extracts the signal strength information from one of the FFT files that it has already generated from a selection of SDR I/Q files.   In Figure 5, two stations’ signals, from Radio Taiwan International, and from CNR2, were featured in the display.   With roughly 4Hz difference between the two signals, it is easily possible with Carrier Sleuth to derive signal strength from each one, specifying a bandwidth of, say 1.2Hz, to account for the propagation induced drifts and smearing of the carriers, not to mention any drift in either the receiver or transmitter.

The program creates a .csv file (text with comma delimiters) of signal strength versus time for all the frequencies chosen from an individual FFT file, but does not plot them.  There are several programs that can create plots from CSV files   For example, an Excel plot generated from Figure 5 is in Figure 8, showing peaks in those signals that occurred both before and after local sunrise at 15:42UTC.   Note that the user is not restricted to the signals found on just one of the waterfalls that are found in the FFT file, but can pick and choose dozens of signals found anywhere in those waterfalls.    (Note also that one can choose locations on any waterfall where there is no signal trace, in order to provide a “background level versus time” in the finished plots, if desired)

The process used to generate this CSV file involves searching through the FFT waterfalls for signal traces that are likely candidates for adding to such a file.   On the first candidate found, the user right clicks the mouse on the trace, at the exact frequency desired; this will bring up an editable window.   The window will show the chosen frequency as well as any subsequent ones that will be chosen, then the overall selection is saved to a text file after editing, so that the user can move on to generating the CSV file.

That file is created by going to the File drop down menu, and choosing “Generate CSV File”, where the text file produced earlier can be chosen.  Once that file is selected, the CSV file is immediately generated, and can then be manipulated separately as the user chooses.

Are there comparable programs?

Displaying waterfalls in SDR programs playing back their own files is nothing new, though not that many can do it at as fine a scale as Carrier Sleuth does, and most programs are not optimized to handle such a variety of input I/Q files.

One that does read a fair number of different kinds of SDR files is the SDR Console program; this includes Data File Analyser (64-bit only) which also can display carrier tracks to a high resolution, so let’s take a quick look at what Analyser does.  If you are familiar with SDR Console, and are reasonably experienced with the way it handles your SDR or plays back files from your favored SDR software, then these online instructions https://www.sdr-radio.com/analyser will help you get started with Analyser

This program will input a group of SDR files, then display an equivalent to a single one of the waterfalls output by Carrier Sleuth, displaying the carrier traces in reverse order, with time running from bottom to top of the display. Figure 9 shows the equivalent of Carrier Sleuth’s display of the 1287kHz carrier traces shown in Figure 3.    Analyser has a convenient sliding cross hair arrangement (shown in the yellow oval) to reveal time and frequency at any point in the display, but the actual signal power available at that point must be derived from the rough RGB scale along the left hand border. Analyser is apparently capable of about 0.02Hz resolution when reading from full bandwidth medium wave SDR files, but the default is to display exact frequency only to the nearest Hertz. The “Crosshairs” ribbon item has a drop down of “High-Resolution”  which displays to the nearest milliHertz however, though that will be limited by the actual RBW of the generated display.   The graphic display can be saved as a project after the initial generation of the signal traces, which allows the user to return to the display without having to generate it all over again, equivalent to opening one of Carrier Sleuth’s FFT files.

A useful facility in Analyser is the ability to click “Start” in the Playback segment of the ribbon above an Analyser display, then mouse over and click on a signal trace; this action will play back the audio for that channel in SDR Console, at that point in time.

It is possible to generate a signal strength plot of signal strength versus time for any individual frequency in the waterfall display, and to save that plot as a CSV file (“Signal History”).   But, the signal strength is that found only in a +/- 0.5Hz passband around the chosen frequency, with no other possibilities.  If you want to generate a plot for another frequency on the same waterfall, then you will need to run the process again, and if you want a plot for another frequency in the SDR files, then you need to generate another waterfall, which, depending on your computer’s capability, could take some time.   On an i3 CPU-based netbook with 4GB of memory, it took 30 minutes to produce one frequency’s worth of traces from data files scanning three hours.  On the same machine, Carrier Sleuth could deliver all 9kHz channels in 1hr20min from the 3 hours of files.  However, it also took 1hr20min to play back just one channel in Carrier Sleuth, which is not so efficient. (further note:   Nils Schiffhauer has developed a technique to speed up Data Analyser processing, by first using Console’s Data File Editor on full bandwidth MW recorded files; details will likely appear at https://dk8ok.org)

To conclude then, SDR Console’s Analyser will produce a display of a single channel faster than Carrier Sleuth will, and will play back the audio associated with that channel, while also having the capability to plot and record signal strength for a single given frequency within that display, but only on 64-bit computers.  It can also handle SDR files larger than 2GB in size, and will run more quickly if a NVIDIA graphics card has been installed.   Analyser is also strict about sequence of files.  If there is the slightest gap between one file finishing, and the next file starting in time sequence, it regards that as a new set, that will need to be processed separately.

Where Carrier Sleuth is more useful is that once an FFT file has been generated, it is easy to quickly check multiple channels for interesting openings during the recorded time period. It can also provide very precise frequencies of carriers, and is able to generate a file of signal strengths versus time from multiple frequencies, including those frequencies that are separated by barely more than the RBW.  For the MW band, that can be near 0.1Hz, often beyond the capability of transmitters to be that stable.  See Figure 10, which shows signal strength traces from JOCB and HLQH both on 558kHz, and separated in frequency by 0.1Hz.    At 1324UTC, JOCR dominates with men in Japanese, and at 1356UTC, the familiar woman in Korean dominates, indicating HLQH.

Figure 9

Figure 10

Incidentally, another program that seems to offer a similar functionality to Carrier Sleuth and SDR Console’s Analyser is, of course, Jaguar, which has made a point of displaying 0.1Hz readout resolution when using the Perseus SDR, and in playing back Perseus files, but…only Perseus.  There is a capability called Hi-Res in Jaguar Pro that can be applied when playing back files; this also displays fine scale traces of frequency versus the passage of time.  Steve VE6WZ, sent the example shown in Figure 11, zeroing in on his logging of DZAR-1026.  As with Analyser, clicking on a certain point in the display plays back the audio at that time, but it is unclear at this point whether the display can be saved, or whether it is generated only for one individual channel, and then is lost.

Figure 11

+   +   +   +   +   +   +   +   +   +   +   +

Availability

Carrier Sleuth  http://blackcatsystems.com/software/medium_wave_carrier_display_app.html

Analyser (SDR Console)   https://www.sdr-radio.com/download

Jaguar   http://jaguars.kapsi.fi/download/ (these are the Lite versions; to unlock the Pro version, purchase is needed)

(this article first appeared in International Radio Club of America’s DX Monitor)

Many thanks, Nick. This is amazing. What a brilliant tool to find nuances of a DX signal. I can’t help but marvel at the applications we enthusiasts have available today. Thank you for sharing!

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Radio Waves: New Quantum Receiver, Virus and Distance Learning by Radio, BBC Woofferton Early Days, and Hello Morse

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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 Andrea, Kim Andrew Elliott, Dave Porter, and Phillip Novak for the following tips:

New quantum receiver the first to detect entire radio frequency spectrum (Phys.org)

A new quantum sensor can analyze the full spectrum of radio frequency and real-world signals, unleashing new potentials for soldier communications, spectrum awareness and electronic warfare.

Army researchers built the quantum sensor, which can sample the radio-frequency spectrum—from zero frequency up to 20 GHz—and detect AM and FM radio, Bluetooth, Wi-Fi and other communication signals.

The Rydberg sensor uses laser beams to create highly-excited Rydberg atoms directly above a microwave circuit, to boost and hone in on the portion of the spectrum being measured. The Rydberg atoms are sensitive to the circuit’s voltage, enabling the device to be used as a sensitive probe for the wide range of signals in the RF spectrum.

“All previous demonstrations of Rydberg atomic sensors have only been able to sense small and specific regions of the RF spectrum, but our sensor now operates continuously over a wide frequency range for the first time,” said Dr. Kevin Cox, a researcher at the U.S. Army Combat Capabilities Development Command, now known as DEVCOM, Army Research Laboratory. “This is a really important step toward proving that quantum sensors can provide a new, and dominant, set of capabilities for our Soldiers, who are operating in an increasingly complex electro-magnetic battlespace.”

The Rydberg spectrum analyzer has the potential to surpass fundamental limitations of traditional electronics in sensitivity, bandwidth and frequency range. Because of this, the lab’s Rydberg spectrum analyzer and other quantum sensors have the potential to unlock a new frontier of Army sensors for spectrum awareness, electronic warfare, sensing and communications—part of the Army’s modernization strategy.

“Devices that are based on quantum constituents are one of the Army’s top priorities to enable technical surprise in the competitive future battlespace,” said Army researcher Dr. David Meyer. “Quantum sensors in general, including the one demonstrated here, offer unparalleled sensitivity and accuracy to detect a wide range of mission-critical signals.”

The peer-reviewed journal Physical Review Applied published the researchers’ findings, Waveguide-coupled Rydberg spectrum analyzer from 0 to 20 GigaHerz, co-authored by Army researchers Drs. David Meyer, Paul Kunz, and Kevin Cox[…]

Virus and distance learning by radio (1937, 1946) (AE5X Blog)

Six to eight decades ago polio was one of the most feared diseases in the US. In 1952 alone, 60,000 children were infected, 3000 died and many more were paralyzed.
The most severe outbreaks were in 1937 and 1946. My father was a victim of the 1946 epidemic, suffering minor paralysis in one leg as a child.

In 1937, many schools around the country closed, as did public pools, movie theaters and parks. But the Chicago public school system took an innovative approach.

During that period, 80% of US households contained a radio. This allowed 325,000 children in grades 3-8 to continue their education at home via radio lessons aired by six Chicago radio stations (WENR, WLS, WIND, WJJD, WCFL, WGN) that donated time for the purpose.

Program schedules for each day were printed in the morning paper. Home with more than one radio & more than one child often set up radios in different rooms so that each child could hear the appropriate grade’s lesson.

This continued for one month…until schools reopened in late September of that year.

Curriculum was developed by teachers and monitored over the air by school officials. After each episode, a limited number of teachers were available for phone calls. A large number of the calls were from parents distressed that they could not clearly receive the broadcasts.[Continue reading…]

BBC Woofferton Early Days (Ludlow Heritage News) [PDF]

Very few structures are left in the Ludlow area which can be traced back to the Second World War. However, look five miles south of the town towards the rise of the hills and a tracery of masts can be seen. Go closer, and a large building can be found by the road to Orleton, surrounded now by a flock of satellite dishes, pointing upwards. The dishes are a sign of the recent past, but the large low building was made for the war-time radio station aimed at Germany.

This little history attempts to tell the story of the British Broadcasting Corporation’s transmitting station at Woofferton near Ludlow in Shropshire during the first years of its existence. When and why did the BBC appear in the Welsh border landscape with a vast array of masts and wires strung up in the air? The story begins in 1932, when the BBC Empire Service opened from the first station at Daventry in Northamptonshire. Originally, the service, to link the Empire by wireless, was intended to be transmitted on long-wave or low frequency. But, following the discovery by radio amateurs that long distance communication was possible by using high frequency or short waves, the plan was changed. Later in the decade, the BBC expanded the service by also broadcasting in foreign languages. Although Daventry had a distinguished name in the broadcasting world, it was never technically the best place for a short-wave site, being on a hill and close to a growing town.

This article can be found in the Ludlow Heritage News: click here to download the full PDF.

 

Hello Morse: A collection of AI and Chrome experiments inspired by Morse code on Android Gboard (Google)

Developer Tania Finlayson found her voice through Morse code. Now she’s partnering with Google to bring Morse code to Gboard, so others can try it for accessible communication.

Morse code for Gboard includes settings that allow users to customize the keyboard to their unique usage needs. It works in tandem with Android Accessibility features like Switch Access and Point Scan.

This provides access to Gboard’s AI driven predictions and suggestions, as well as an entry point to AI-powered products, like the Google Assistant.[…]

 

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WRTH 2021: A look inside the 75th Anniversary Edition!

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Last week, I received a long-awaited Christmas gift: the 2021 World Radio TV Handbook. Normally, I’d receive this annual guide in the December time frame, but because of delays in international postal services due to the Covid-19 pandemic, I took delivery a few weeks late.  

I always look forward to receiving this excellent staple radio reference guide–and this is their 75th edition! As I say each year, the WRTH has never disappointed, so my expectations are always quite high.

Once again, the WRTH lived up to my expectations.

WRTH’s team of noted DXers from around the world curate frequencies and broadcaster information by region; while I’m not sure how they orchestrate all of this, the end result is truly a symphony of radio information. In addition to broadcaster listings, WRTH’s radio reviews, feature articles, and annual HF report make for excellent reading.

But the WRTH isn’t just a frequency guide: the publication always devotes the first sixty or so pages to articles relating to various aspects of the radio hobby. Following, I offer a quick overview of these.

The first article always features a WRTH contributor:  this year, they feature Stig Hartvig Nielson. His path to becoming a WRTH contributor began in his childhood when he said he was “tall enough to reach the radio tuning knob and tune away from dull Radio Denmark.”  His love of radio lead him down the path of becoming a broadcaster. Many of us know him via his station, Radio208.

WRTH Reviews

The second set of articles is always my favorite: WRTH receiver reviews.

This year, WRTH begins with an in-depth review of the AOR AR5700D wideband communications receiver–a radio I’d likely never touch in real-life, so it’s wonderful to take such a deep dive.  Next up is a review of the Bonito NTi MegaDipol MD300DX antenna which gets high marks for high gain, low noise, and good dynamic range. The following in-depth review is of the benchmark Icom IC-7610 general coverage transceiver. This was the first time I’ve read a review of this SDR transceiver with radio listeners in mind. WRTH then review the Bonito NTi CCMC30 common mode noise filter–a tool that can help radio enthusiasts mitigate RFI.

A review of the SDRplay RSPdx follows and the review speaks to the performance improvements included with the new HDR mode. The next review is actually one I authored of the Tecsun PL-990 portable radio–it’s always an honor to be in the pages of the WRTH!

The final review is of the Valent F(x) KiwiSDR; a little web-connected SDR receiver that has certainly transformed the nature and accessibility of remote listening.

WRTH Features

The first feature article, written by none other than Dave Porter, focuses on the development of HF broadcast transmitters. This article adds to the one he authored last year which focused on broadcast antennas. Dave is amazing because he has such an extensive history in the world of HF broadcasting and his experience and expertise are obvious in all of his writing. This is a must-read for those who want to know more about the “business side” of an international broadcast signal!

Manfred Rippich’s feature, Radio in Bhutan, explores the story of broadcasting in one of the most mountainous countries in the world where communities–including the capitol–are not easily accessible. Radio broadcasting plays an important role in this amazing country.

The following feature, Coastwatchers & the AWA Teleradio 3BZ written by Dr Martin Hadlow, takes a look at the importance of portable radios in the Pacific War. An absolutely fascinating piece for those of us who love radio history.

The final feature was written by Alan Pennington and explores the dynamic Scandinavian Weekend Radio.  It’s hard to believe SWR has celebrated 20 years on the air as of 2020. Pennington’s article explores the grassroots energy of this unique broadcaster!

The final article–a tradition–is the WRTH  HF propagation report/forecast by Ulf-Peter Hoppe. Always an informative read especially as we continue to work our way out of a long-term solar slump.

The 75th is another fantastic edition of the World Radio TV Handbook. As I say every year, I’ve never been disappointed with WRTH. Their publishing standards are such that the quality of their reviews, their writing, and (most importantly) their broadcast listings are simply unparalleled.

For DXers who collect QSL cards, you’ll find that broadcaster contact information in WRTH is often more up-to-date than a broadcaster’s own website. When readers contact me asking for QSL information from an obscure broadcaster, the first place I search is the current WRTH. Remember: their information is based on volunteer contributors who specialize in specific regions of the world–the most knowledgeable regional DXers keep this publication accurate.

Purchase your copy of WRTH 2020 directly from WRTH’s publishers, or from a distributor like Universal Radio (US) , Amazon.com (US),  or the Book Depository (international).

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National Public Broadcasting Company of Ukraine resumes mediumwave broadcasting

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Many thanks to SWLing Post contributor,  Vlad (US7IGN), who writes:

Hello!

I hasten to inform you the good news that Ukrainian radio resumes broadcasting on medium waves.

At a time when the whole world is curtailing broadcasting, a new station has appeared on the air!

From February 1, the National Public Television and Radio Company of Ukraine will resume broadcasting UA: Ukrainian radio in the medium-wave band on the frequency 549 KHz.

The medium-wave transmitter of UA: Ukrainian radio in the village of Luch, Mykolaiv region, with a capacity of 500 kW, covers most of the territory of Ukraine (during the day – 60% of the territory including the occupied territories, from evening to morning – the whole territory of Ukraine).

http://uarl.info/news/ukrainskoe_radio_vosstanavlivaet_veschanie_na_srednih_volnah

Brilliant news–many thanks for the tip, Vlad!

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Loop-On-Ground Antenna Part 2: Tom upgrades his low profile, low noise, portable DXing antenna

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Many thanks to SWLing Post contributor, TomL, who shares the following guest post:

Loop on Ground Part 2

by TomL

My previous Loop on Ground (LoG) experiment was useful which entailed connecting my Wellbrook loop amplifier to a 100 foot loop of speaker wire in the field at my favorite local Forest Preserve. It really brought in stations I had never heard before or strong stations in a more powerful way that made the audio really pleasant to listen to.  This report will describe more experiments with smaller wire loops to see what the limitations are.  100 feet of wire is quite a lot of wire to mess around with especially in the cold weather or public places that do not have as much private space.

I don’t understand all the electrical interrelationships but a long posting at RadioReference.com had  a great discussion about creating a 160-20 meters LoG receive-only antenna. It is 11 pages long but is worth reading how “nanZor” experimented with various parameters for general use. Kudos to him for documenting the findings as the design changed over time. You can find it here:

https://forums.radioreference.com/threads/160-20m-log-loop-on-ground.370110/

nanZor basically boils it down to a few guidelines.

  1. Keep it on the ground. Lifting the wire more than an inch or two decreased the lower angle signal reception greatly.
  2. Calculate the optimal length for one full wavelength of wire at the highest target frequency, say for example, the top of the 20 meter band (14350 kHz). 936/14.350 MHz * 0.9 velocity factor of simple insulated wire = 58.7 feet.  You can round up to 60 feet, no big deal since this is broadband.  The antenna should have a predictable reception pattern from 1/10th wavelength up to 1 full wavelength. Outside that range, the pattern gets “squirrely”.
  3. Using a 9:1 balun seemed to be a little better than a 4:1 balun at the antenna feedpoint. This gets into things I cannot measure and has to do with rising impedance as a loop gets closer to ground level. I am not sure but I think my Wellbrook amp has a built in 4:1 balun and it seems to work just fine.
  4. Make sure to use an RF Choke at BOTH sides of the feedline coax cable. He was adamant that the loop can get easily unbalanced and allow noise into the antenna and/or feedline and so it must be isolated and the ground allowed to “float” in his words.

Personally, I also wanted to use less wire and happened to have a length of 42 feet of landscape wire which should work well below 5 MHz with the Wellbrook amp engaged.  Results were not bad even though on hard frozen ground. Signal levels were down a little compared to the 100 foot of wire.  Here are a couple of examples, first one in a fast food parking lot with a grass field next to it and second at the usual Forest Preserve parking lot on a grass field.  I made sure that my car blocked the view of the wire so people would not get nervous!

La Voz Missionaria, Brazil:

Voice of Welt from Issoudun France in Kurdish:

These are not necessarily “DX” but definitely good for SWLing. I like the signal strength with the amplifier inline at the antenna feedpoint and I did not have to use an RF Choke at the receiver side as was suggested.

I had a 75 foot long insulated wire and used that at the Forest Preserve parking lot on a couple of different days.  Lower frequency signal strength and signal/noise ratio improved a little bit to be noticeable.

US Air Force HFGCS “numbers” station. Remote controlled from Andrews or Grand Forks bases (https://en.wikipedia.org/wiki/High_Frequency_Global_Communications_System), there was no way for me to know which of the 6 transmitters it was coming from:

BBC from Tinang Philippines in Korean:

Then, as nanZor suggested in his postings, I purchased a 9:1 balun/RF choke (it has both a balun and an RF choke built-in) from Ham Radio Outlet and put that in place of the Wellbrook amplifier.

I have not worked with it, but it is reported that the Nooelec.com v2 model is cheaper and works just as well – https://swling.com/blog/2019/10/the-nooelec-balun-19-v2/

Examples below with the 42 foot loop and 9:1 balun/choke, no amplifier:

KSDA, Agat Guam in English

WB8U doing a POTA activation of Leavenworth State Fishing Lake

VOLMET weather, Shannon Ireland

HCJB Quito Ecuador, probably in Quechua

As a side note, there is a posting that mentions low-angle DX is better with regions that have better “ground conductivity”, salt water being the best. I have no way of verifying this.  See post# 126 by KK5JY Matt.

So, bottom line is that a Loop on Ground can be useful for pleasant SWLing and portable.  Best to use it on grass, not asphalt.  The loop amplifier is useful to get signal levels up if you have to use a smaller loop size but the signal/noise ratio will suffer due to its smaller aperture.  And, warning, the public will find a way to trip over the wire no matter where you set it up (I may try putting the wire around my car if I can park on a grass surface and/or use the gaudiest, brightest neon green or orange wire I can find – they can’t trip over THAT, can they?).

TomL

Thanks, Tom, for sharing your update. Obviously, the LoG is working brilliantly. It’s amazing that you got such clear reception from the parking lot of a fast food restaurant.  If you were using a vertical instead, I bet signals would have been buried in the noise. 

I can also relate to people tripping over antenna wires. I remember one POTA activation recently (the first activation in this three park run) where I intentionally laid my counterpoise on the ground, off a foot path, in the brush and where I couldn’t imagine anyone ever stepping. Ten minutes into the activation and for no reason, someone walked off the path, into the brush, and it snagged them. Maybe I’m just a Ninja level trapper and never realized it!?

Thanks again for sharing the results of your LoG, Tom. Inspiring! 

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Is AM synchronous detection a crucial portable radio feature?

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Many thanks to SWLing Post contributor, Mike, who writes with the following question:

How important is AM Sync for a portable radio? Is it essential or a deal breaker?

That’s a great question, Mike, and one I don’t think I’ve directly addressed it here on the SWLing Post oddly enough.

Synchronous detection is actually a fairly deep topic to explore–and everyone has their own opinion–but I get the impression that you’d like a simple answer, so I’ll try to keep this as brief as possible. You might follow the comments section of this post as I’m sure some SWLing Post readers will share their thoughts on synchronous detection and how important it is for them.

So what is Synchronous Detection?

I like this concise Wikipedia answer:

In electronics, a synchronous detector is a device that recovers information from a modulated signal by mixing the signal with a replica of the un-modulated carrier. This can be locally generated at the receiver using a phase-locked loop or other techniques. Synchronous detection preserves any phase information originally present in the modulating signal. Synchronous detection is a necessary component of any analog color television receiver, where it allows recovery of the phase information that conveys hue. Synchronous detectors are also found in some shortwave radio receivers used for audio signals, where they provide better performance on signals that may be affected by fading. To recover baseband signal the synchronous detection technique is used.

How does synchronous detection help shortwave, mediumwave, and longwave listeners?

As the Wikipedia article notes above, sync detection can help “provide better performance on signals that may be affected by fading.”

In short: a solid synchronous detector can help stabilize an AM signal which then can help with overall signal intelligibility.

In some modern portable radios, at least, this could come at the expense of audio fidelity (see caveat below).

I use sync detection when the bands are rough, noisy, and QSB (fading) is affecting signals.

A good sync detector will help clean-up and stabilize the signal so that you can hear voice information with less listener fatigue. Sync detectors are also great tools for grabbing station IDs when propagation is less stable. If you have a receiver with selectable sideband synchronous detection, it can also be used as a tool for eliminating adjacent signal interference.

Caveat? Sync detectors vary in terms of quality.

The PL-880 has a synchronous detection “hidden” function. I’m sure it’s hidden because it’s so ineffective. The PL-880 is a fantastic portable, but don’t bother using the sync detector.

Many modern DSP portables sport synchronous detection, but they’re not terribly stable and the audio fidelity can take a big hit as well. Poor sync detectors can make audio sound “tinny” and narrow.

If a sync detector isn’t effective a providing a stable lock on a signal, then it’s pretty much useless. Why? If it can’t maintain a stable lock, it’ll produce very unstable shifting audio, often with the occasional heterodyne sound popping in as well. In those cases, it’s better to turn off synchronous detection.

Benchmark legacy tabletop receivers and modern Software Defined Radios (SDRs) typically have solid, effective sync detectors. Indeed, I rarely have the AM synchronous detector disengaged on my WinRadio Excalibur–that particular SDR and application enhance audio fidelity through sync detection.

I find that I use sync detection less with my Airspy HF+ Discovery and SDRplay RSPdx, for example, because the OEM applications natively does a brilliant job managing unstable signals.

In terms of portables, I’ve always considered the sync detector of the Sony ICF-2010, Sony ICF-SW7600GR, and PL-660/PL-680 to be pretty solid. I’m sure readers can suggest even more models.

Is sync detection an essential feature on a portable radio?

Not for me. But I do admit that I value the radios I own that sport a good sync detector.

For some SWLs and DXers, however? It might very well be a deal-breaker if a radio doesn’t have a sync detector, or if its sync detector doesn’t function well.

What do you think?

Is the lack of sync detection a deal-breaker for you? When do you employ sync? Please comment!

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