Tag Archives: Software Defined Radio

Meeting WavViewDX Developer Reinhard Weiß, and Visiting Akihabara With Him (A Totsuka DXers Circle Article by Kazu Gosui)

Meeting WavViewDX developer Reinhard Weiß, and Visting Akihabara With Him

by Kazu Gosui

I first learned about WavViewDX in January of this year on the mailing list of the American radio club IRCA. It was described as “analysis software compatible with I/Q WAV recordings created with almost all SDR software,” so I was intrigued. I quickly downloaded it and tried it out, and I was immediately impressed.

In early February, I emailed the developer, asking, “I’m amazed at how easy it is to use and how powerful it is. It works fine with PERSEUS and AirSpy HF+, but are there any plans to support WiNRADiO’s DDC format?” Reinhard Weiß (hereafter referred to as Reinhard) responded that same day, “I’m actually currently working on adding support for WiNRADiO’s G33DDC. I should be able to send you a test version tomorrow.” The email carefully explained the import procedure and important points to note.

The text, the web page description, and the tone of the expression conveyed a sincere and attentive personality. The next day, I tried out the sample version and reported some concerns. Reinhard quickly fixed them, and where he couldn’t immediately fix them, he supported me by sending files via the cloud or screen capture videos. As I continued to request things like adding a shortcut for switching receive modes, I gradually became fascinated with WavViewDX and, before I knew it, became a heavy user.

The first email also asked, “I’m planning to visit Japan in May or June. Are there any ham or BCL (Broadcast Listener; SWL) events in Japan around that time?” In response, I suggested that if Reinhard could come to Tokyo, we could hold an offline meeting with members of TDXC! Through our exchange, I realized that Reinhard is quite knowledgeable about Japanese affairs. He knows Akihabara very well, and even knows Hard Off as a good place to get BCL radios. He loves hot springs and enjoys talking about Japanese food. When I asked him, “Is your wife Japanese by any chance?” he replied, “Yes.” No wonder he’s so knowledgeable! He should have told me sooner! (lol) So, we made an appointment for an offline meeting in Akihabara, Tokyo, in late May.

On the day, we met at the Electric Town exit of JR Akihabara Station. Our four attendees were Hiroo Nakagawa, Satoshi Miyauchi, Fumiaki Minematsu and myself. When I arrived at the meeting point five minutes early, they were already there. When I asked him, “Excuse me, Reinhard-san?” he replied, “Yes, that’s right,” in Japanese. His Japanese was fluent! Up until now, emails had been in English, as I don’t speak German, so I had no choice but to communicate in English… I was completely surprised because I had been counting on the others and Google Translate on my smartphone to converse in English! You should have told me sooner, Reinhard! (lol) Needless to say, from then on, the entire conversation was in Japanese. The meeting venue was a pub near the station. He could read the Japanese menu, and thanks to his wife, who is apparently a good cook, Japanese food was also OK, so no problem.

We spoke about radio and BCL. Reinhard started medium wave DX about three years ago. He has been interested in radio since he was a child and actually worked as a BCL radio broadcaster. He has had a long career. His job is developing debuggers for testing and verifying the operation of in-vehicle electronic devices and measuring instruments. He says that both his work and his hobby are focused on developing easy-to-use hardware and software integration. He developed WavViewDX while studying the programming language Python, and runs it at home using two PERSEUS devices.

He said he would be happy if many people use it. Currently, WavViewDX has 200 users, 25 of whom are active worldwide. Incidentally, the mailing list has 102 subscribers (as of June 10, 2025).

Over lunch, we had the opportunity to use WavViewDX on the PC we brought with us, and it was extremely valuable to have the developer himself explain how to use it, provide an overview of its functions, and explain the development concept. We also received copies of the German BCL magazine “Radio-Kurier” (a radio delivery service?). This magazine apparently publishes an astounding 2,000 copies per month, demonstrating the depth of Germany’s BCL population. The most active BCLs are few, and 80% of the articles are written by one person. That’s impressive.

The second half of the meeting was a tour of Akihabara’s famous shops. We visited the Radio Center rental showcase, Uchida Radio, Radio Department Store, Rocket, Fuji Musen, and Akizuki Denshi. Reinhard has a keen interest in vintage Japanese BCL radios and boomboxes, and his eyes lit up as he looked at rare radios and boomboxes. At Uchida Radio, he even negotiated the price of a radio cassette player he was interested in. Unfortunately, the deal fell through, but he apparently toured Hard Off stores around Tokyo the next day, so he must be a die-hard enthusiast. He also seemed to love the Fuji Wireless and Akizuki Electronics stores on the second floor, saying, “Their unique products are what keeps them going, and I can see why they’ve survived.” He bought a large breadboard (brand new!) for 50 yen on the second floor of Akizuki and then we took a break for tea in the cafe.

We had a great time chatting there, too. Reinhard is, in a word, a nice guy. A German who speaks Japanese, loves radio and BCL, and develops software for BCL—an extremely rare and valuable person. He’s fluent enough in Japanese to even tell jokes, and he’d laugh along with us at our old-man jokes. He was friendly and fun to talk to, and we shared the same values as fellow enthusiasts. It felt like we were old friends.

He apparently returns to Japan every year with his wife, but he hasn’t done a DX expedition yet. Maybe the next one will be the Chigasaki expedition?! So we parted ways, hoping to see each other again next year.

(l-r: Kazu Gosui, Satoshi Miyauchi, Hiroo Nakagawa, Reinhard Weiß, Fumiaki Minematsu) —Hiroo Nakagawa photo

(l-r: Kazu Gosui, Hiroo Nakagawa, Reinhard Weiß, Satoshi Miyauchi) —Fumiaki Minematsu photo

These English translations were prepared for IRCA’s DX Monitor, and are used with the kind permission of IRCA as well as of the authors and the editor of the Totsuka DXers Circle publication, PROPAGATION.

Ultra Convenient, The Benefits of WavViewDX: Visualizing Reception Conditions (A Totsuka DXers Circle Article by Satoshi Miyauchi)

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Many thanks to SWLing Post contributor Nick Hall-Patch, who has kindly provided a translation of this article from the Japanese-language publication PROPAGATION by the Totsuka DXers Circle (TDXC). In this piece, Satoshi Miyauchi explores how WavViewDX can revolutionize SDR analysis by making propagation and reception conditions instantly visible–and shares some remarkable reception examples.

“Ultra” Convenient, The Benefits of WavViewDX: Visualizing Reception Conditions

by Satoshi Miyauchi

After recording bands using SDR’s such as Perseus or HF Discovery, I was informed by Kazu Gosui via email of a new program that’s “ultra” convenient for analyzing them. When monitoring in real time with Perseus, I have a general memory and notes of what was received at what time. However, when recording reception data without real-time monitoring, such as during nighttime hours, verifying and analyzing the data across all frequencies takes time. Knowledge and intuition about where to listen are also important elements. While all of this is a skill, I believe that previous tools have been unable to provide a comprehensive view of the day’s conditions. Since I started using WavViewDX, I’ve been using it every morning, efficiently analyzing the SDR recordings I’ve collected.

By the way, recently I’ve been using a timer (the “Scheduler” of SDR Console) to check if the TWR-Africa signal transmitted from Benin, West Africa, is reaching me in the middle of the night. My analysis showed a significant reduction in the time required for confirmation that TWR-Africa was being received before and after WavViewDX was installed, and I’d like to share this with you.

Just to be clear, this article is not intended to be a tedious rehash of the user manual. Rather, it is intended to provide useful, pinpointed tips for use.

I’ll introduce a method I think might be best based on my current setup.
I’ll share some reception reports from my recent morning routine.
I’ll touch on the mysteries of radio wave propagation, a realization I believe is unique to WavViewDX.

But first, a word about WavViewDX: seeing is believing. As shown in the sample image in Figure 5, it visually displays the status of stations received at each frequency, using green bars or white lines, in chronological order, from the lowest frequency band (left) to the highest (right). You can even customize it to analyze North and South America at 10 kHz intervals for TP reception.

The author is Reinhard Weiß from Germany (please see accompanying related articles). It is an incredibly easy-to-use and intuitive software. Once you start using it, you’ll definitely want to keep it.

Figure 5

First, let’s assume you’ll be importing and analyzing data into WavViewDX.

1.) Timer Reception Tips, Using SDR Console

This is a backward-thinking approach based on the fact that WavViewDX can import files in “folders.” The golden rule is simply to store all files from a single session in a single folder. I’ve been using SDR Console as my primary SDR program for a while now, so when I register a scheduler (for timer scheduling), I click “Add date (yyyy-mm-dd) subfolder” under “Folder”, in Figure 6. This allows me to import the entire folder of recording files from that day into WavViewDX, saving me a lot of time. WavViewDX has a “Select Whole Folder” button, which allows me to import files into WavViewDX with a single click (Figure 7). How amazing! Incidentally, I set up bandwidth recording files to be stored in separate 1GB files. The moment I wake up, the files are instantly imported into WavViewDX, allowing me to quickly check the conditions from midnight to dawn before work.

Figure 6

Figure 7

2) TWR-Africa Reception Recording

Even on shortwave, it’s rare to see signals from Africa, let alone on mediumwave. Until a few years ago, I thought this was impossible. However, I discovered that I could record pre-dawn signals from Africa on my home K9AY loop, including the VOA of the Sao Tome and Principe relay on 1530kHz, as well as the famous TWR Africa (Benin) on 1476kHz. Of course, it’s not easy to receive signals every day, so I was not motivated to record them regularly However, after installing WavViewDX, I was able to easily grasp the pre-dawn conditions, and I set up a scheduler to record as many times as possible every day.

Then, one morning, right around 3:30 AM, on the morning of the March vernal equinox, I noticed a very clear bar on the 1476kHz using WavViewDX (Figure 8). By working in conjunction with WavViewDX, it automatically checks offsets in exact carrier frequency being received against the MWList database, and the > mark quickly lights up in WavViewDX, indicating that it’s TWR Africa! I was surprised when I heard the audio. I was impressed by the exceptionally clear reception. There was a slight beat, and it seemed like at least one other carrier was also in the mix. How such clear audio managed to reach and be heard across nearly 13,300 km as the crow flies is a mystery, but it’s still a moving experience.

Figure 8

I asked @lft_kashima LFT Kashima Fishing Radio, who regularly posts information on X, and he said that the signal wasn’t as good on that day at his location. Since we’re both in the Kanto region and a little farther apart, perhaps that’s the problem, or perhaps it’s just the antenna. He uses a north-south loop antenna, while I use a vertical AOR SA-7000.

While I don’t know the full reason or answer, one possible guess: – Wasn’t the arrival direction north-south? – Did it arrive through a duct somewhere? However, there’s no way to know why the duct ended up at this receiving point. It’s a wonder that I was able to receive such a DX station at this point in the solar cycle, when the number of sunspots is almost at its maximum and the A/K Index was far from calm. This makes daily reception all the more meaningful. It’s a moment that makes me admire nature, the work of radio wave propagation. I was able to receive this station again in April, and the links to those two results from 1476kHz – TWR Africa are below:

Received Audio 1: March 19, 2025, 18:35 UTC https://youtu.be/gWORriKCJ7c
Received Audio 2: April 14, 2025, 18:31 UTC https://youtu.be/DfYn-gbp2SY

3) The Mysteries of Radio Wave Propagation Discovered Only with WavViewDX

WaveViewDX already clearly shows the reception status on the vertical time axis, but just before the vernal equinox, a phenomenon in which the propagation conditions deteriorated simultaneously across multiple frequencies occurred, albeit for a short period of time. (Audio Sample https://youtu.be/XhXSQFiGQeo) What is this? Figure 9 shows the actual situation at my location on March 17, 2025, after 18:00 UTC.

Figure 9

1278kHz JOFR Fukuoka RKB Mainichi Broadcasting System 50kw (about 900km distance, 245°)
1287kHz JOHR Sapporo HBC Hokkaido Broadcasting System 50kw (about 1000km distance, 340°)
1332kHz JOSF Nagoya Tokai Broadcasting System 50kw (about 270km distance, 270°)

(*Note: The leftmost bar (1242kHz in the Kanto region) is attenuated with a notch filter)

One of the benefits of WavViewDX is that it visually showed the simultaneous drop in signal strength from domestic and international stations, which had been arriving almost smoothly until 18:00 UTC.

I asked Perplexity AI and searched the literature. These possibilities were listed:

“Regarding the phenomenon of simultaneous attenuation of radio signals in all directions for several minutes during nighttime propagation in the medium frequency band (MF band),” it is believed to be primarily caused by the combined effects of the following factors: –

Ionospheric Variation Mechanism Sudden E-Layer (Es-Layer) Formation A localized increase in electron density in the upper E-layer of the ionosphere (at an altitude of 100-120 km) at night. This thin ionosphere strongly reflects signals, blocking the normal F-layer reflection path. One measurement data showed signal attenuation of up to 20 dB when the Es layer occurred.
F-layer altitude fluctuations: When the F layer (altitude 250-400 km), the main nighttime propagation path, rapidly rises due to thermal expansion, the reflection angle changes, creating a “propagation hole” that causes signals to deviate from the receiving point.
Earth’s magnetic field fluctuations disrupt the electron distribution in the ionosphere, causing a sudden increase in absorption.
Instantaneous changes in solar activity: The emission of X-rays and charged particles associated with solar flares suddenly changes the electron density in the ionosphere, destabilizing the reflection coefficient and resulting in short-term propagation loss.

Although it was able to provide various possible explanations, I was unable to perform any further verification of these answers myself.

An Introduction to WavViewDX SDR Playback Software (A Totsuka DXers Circle Article by Kazu Gosui)

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Many thanks to SWLing Post contributor Nick Hall-Patch, who has kindly provided a translation of this article from the Japanese-language publication PROPAGATION by the Totsuka DXers Circle (TDXC). In this piece, Kazu Gosui introduces WavViewDX, an impressive SDR file playback and analysis tool developed by Reinhard Weiß of Germany.

About WavViewDX, SDR File Playback Software

by Kazu Gosui

Introduction

“WavViewDX,” developed by Reinhard Weiß of Germany, is SDR file playback software. It maps the received signals from SDR-recorded files into bar graphs, with time on the vertical axis and frequency (channel) on the horizontal axis, for each of the following channel separations: medium wave (9/10 kHz), short wave (5 kHz), and FM (50/100 kHz). Clicking the cursor (blue crosshair) plays the received audio. By “visualizing the received signal” through mapping (see also the separate article by Satoshi Miyauchi), you can see at a glance the start and end times of broadcasts, fade in, fade out, channels you should listen to, and channels you don’t need to listen to.

Basic Usage and Screen Description

First, download and install WavViewDX from the WavViewDX webpage (https://rweiss.de/dxer/tools.html). The latest version is version was 1544 as of June 8, 2025, when this was written, but version 1662 is available in October 2025. When you launch WavViewDX, the Main Window (Figure 1) will appear, showing Analysis View, the Operation/Settings Panel, Logbook and Database.

Figure 1

To play back recorded files, you must import them. Click Import to display the Import SDR Recording settings screen. Source files can be selected as single or multiple files, or by folder. Set the reception location, time, channel separation, etc., and begin importing. A progress percentage will appear, and green and white bar graphs will appear on the Analysis View screen. Hovering the cursor over a bar graph and clicking will display a red circle, and the audio recorded for that channel and time will play. Scrolling the mouse will allow you to zoom in and out of the Analysis View.

When you import, a WVD format file is created. Once you’ve imported the files, you can simply load the corresponding WVD file at another time, and the files will be available to play immediately.

In addition to Import and Load, the following settings are available at the top of the Main Window.

Analysis: Allows you to select the file/folder and frequency separation when importing.
Carrier Views: Displays offset frequencies to identify and estimate the received medium wave station.
Database: Links with the MWLIST webpage (https://www.mwlist.org/ul_login.php) to identify and estimate the received medium wave station.
Logbook: For documenting stations heard, along with creation of audio recordings during playback.
More: Allows you to set multiple options, such as manual tuning and contrast setting.
Setup: Allows you to set the sound device and select the file format for recording audio clips during playback.
About: Allows you to select the software version, Help, etc.

The Main Window also displays the frequency list linked to the aforementioned Database and the Logbook. The database frequency list can be selected by region, such as Europe or East Asia. The Logbook allows you to record reception records and associate recorded audio files.

The right side of the Main Window contains the operation and settings panel. At the top are the Frequency Display and Spectrum View. Hovering the cursor over Spectrum View allows you to select PBT (Pass Band Tuning) and NOTCH.

Below these are:

Spectrum Zoom (x1, x2, x4), which expands the spectrum;
Bandpass Bandwidth Presets ([2.5] etc.), which change the reception bandwidth;
Player Time Controls (Play/Pause; -30s etc.), which control the playback time;
Carrier View, which displays the offset frequency; (+/- 30Hz, and can be shifted above and below the nominal .000 frequency)
Demodulator Modes, which change the reception mode.

(Keyboard shortcuts are available for the above functions.)

The AF Highpass Filter adjusts the audio frequency passband to improve intelligibility.
The Spike Filter reduces popping during reception.
Phasing combines two synchronized recording files to reduce same-frequency interference and noise.
NCE (Neighbor Channel Eliminator) reduces interference from adjacent channels.
Binaural allows you to select the sideband of the AF output during playback.
The AF Audio Recorder allows you to record by clicking during playback. Recording formats include WAV, FLAC, and MP3.

As you can see, there are so many features it’s impossible to introduce them all. Detailed adjustments to each function make it even easier to use; it may seem tedious at first, but give the features a try. The user interface is intuitive, so you’ll quickly get used to it. If you’re unsure how to use something, just press the F1 key and refer to the Help.

Actual Usage

Let’s try it out. The import settings are set to MW 9+10kHz Channel Analysis Configuration. Configuration, and other settings are set to default. (editor’s note: “SDR Calibration” allows the use of reference carrier frequencies in the data, for those SDRs without a frequency standard, so that each carrier frequency in the passband will be displayed accurately.) Once the import is complete, a bar graph will appear. Figures 2 and 3 show the analysis view of the actual file import from early May 2025, during the Hachijojima DXpedition showing evening reception; time is UTC.

Figure 2

Figure 3

9kHz separation is used in Figure 2. You can hear the audio from 630kHz at the time indicated by a circle. Black areas of the bar graph indicate no signal, while white to green indicates good signal reception. If you miss an ID during reception, press the up arrow key to rewind the time by 5 seconds and listen again. Click Recording to record the ID.

As you can see, the bar graph color changes from black to white and then white to green over time. This indicates that as the day turns from daytime to evening and then nighttime, channels that previously had no reception begin to receive broadcasts. Sunset on this day was 9:29 UTC (18:29 JST), and the received signal fade in was between 8:30 UTC (17:30 JST) and 9:15 UTC (18:15 JST).

Next, click Analysis and switch to MW 10kHz channel analysis. The Analysis View after switching is shown in Figure 3. This shows the reception status with 10kHz separation. Most channels are black, with a few white spots. There is very little green. In this image, there are certainly no 10kHz channels with good audio, but by clicking on the white, we can see some with faint English talk and music. I checked the database and found that these channels appear to be Hawaiian stations (see orange circle marks in Figure 3) that have been active since around 8:30 UTC.

Also, Latin music was heard on 1230 kHz (Orange circle in Figure 3). This may be Radio Dos from Argentina. By visualizing reception status like this, I was able to determine where to listen and where not to listen. During the Hachijojima expedition in May, I was blessed with outstanding reception conditions from the evening through the early morning hours of the following day, and was able to track 187 overseas medium wave stations, including 165 in Australia, 5 in New Zealand, 2 in Papua New Guinea, Solomon Islands, Tonga, Marshall Islands, Kiribati, Palau, Fiji, Tuvalu, Indonesia, and the Philippines, achieving significant results. Playback and analysis took about a week, which was shorter than usual, thanks to WavViewDX.

Summary

As mentioned above, WavViewDX has proven to be an efficient tool for analysis, allowing users to discover previously unnoticed stations. Since it can play files recorded with various SDRs, we hope that many DXers will use it. WavViewDX is compatible with multiple PC operating systems, including Windows, Linux, and macOS, and is freeware. According to Reinhard Weiß, additional features and enhancements are planned for the future, so we look forward to seeing its future developments. Finally, we would like to express our gratitude and respect to Reinhard Weiß for developing such useful and excellent software.

Reference Materials

WavViewDX Homepage https://rweiss.de/dxer/tools.html
Radio-Kurier – weltweit hören https://www.radio-kurier.de/

Table 1. Supported IQ Formats

ELAD FDM-SW2	Generic RAW recordings
GQRX recordings	HDSDR
Jaguar	Linrad RAW, single and dual-channel
recordings	PERSEUS (*.wav)
PERSEUS P22 (*.P22)	SDR#
SDR Console	SDR Uno
SDRconnect	SpectraVue
WiNRADiO DDC	WiNRADiO RXW (only for G33)
Winrad

Trying WavViewDX on FM

WavViewDX is primarily geared toward medium wave DX, but it seems like it can be used for FM DX as well. The image in Figure 4 shows reception from 79-87MHz using an RSPdx-R2 and an indoor YouTwin antenna. It supports stereo and has good audio quality. With an outdoor antenna, it could also be used for FM DX, such as with sporadic E and other short-lived propagation enhancements.

Figure 4

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

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Finding Rare DX with the Data File Analyzer

By Don Moore

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 →

HF Signal Enhancer for SDR: A Hands-On Build by Steve Allen (KZ4TN)

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Many thanks to SWLing Post contributor Steve Allen (KZ4TN), who shares the following guest post:

SDR Signal Enhancer

by Steve Allen

I came across this HF Signal Enhancer for SDR on the RTL-SDR.com website. It was designed and built by Peter Parker, VK3YE from Melbourne, Australia. Below is the link to the video of the signal enhancer in action using an RTL-SDR V4 Software Designed Radio;

www.youtube.com/watch?v=W6OXc_wZTXU

It was very easy to see and listen to the improvement to the signal reception the signal enhancer made. Having been a life-long shortwave listener and current SDR user, I had to build one.

I did a screen capture of the schematic, re-drew it using MS Word, and built the bill of materials. In Peter’s original design he included a T-R relay so you could use the SDR along with a transmitter, which I opted to leave out. I had the passive components in my “junk box” but had to source the enclosure, controls, and antenna connectors. I have used these clam shell extruded enclosures with previous projects and love the build quality and the fact that they incorporate a slot in the sides which let me insert a sheet of PCB material on which I can do the assembly.

Referring to the schematic drawing in Peter’s video, you can see that the variable capacitor “floats” above ground, which is not the usual application for these devices. To do that I mounted the vari-cap on a piece of non-plated PCB material that I cut to the width of the enclosure and it fit nicely within the slot. The vari-cap had three pins on the side of the frame that allowed me to force fit it into three holes I drilled in the PCB material. I was very careful to drill the holes undersize and then slowly open them up until the vari-cap press fit on to the board. For good measure I ran UV curing adhesive down into each hole, letting it flow all the way through before I set it with a UV light source.

I then drilled an oversized hole in the front panel for the vari-cap shaft to pass through.

I then mounted the RF gain and band switch. The next step was the assembly of the AM broadcast filter. As SDRs can be overpowered by local AM radio stations Peter choose to include an internal band pass filter that is configured for around 3.5 MHz. The intent of this filter is to attenuate the signals below 3.5 MHz. Strong AM stations will still be heard but there is much less chance of them bleeding through on the higher frequencies.

I assembled the filter on a piece of perf board and connected the component leads on the bottom. I passed leads back up through the perf board for the signal path and ground. I mounted it on the main board with a standoff.

The next step was the wiring of the inductors to the rotary switch. Simple, and I tied them to the vari-cap frame.

For the back panel I chose an SO-239 and a BNC for the antenna input, and for the radio connection an SMA and another BNC. I sanded off the coating on the enclosure at the antenna mounts as well as the four corners where the back panel screws into the top and bottom of the clam shell enclosure to provide good grounding of the enclosure. I wired the 1N4148 diodes on the antenna connectors, and attached the RG-174 coax. As Peter suggested, I grounded the long (relatively speaking) runs to and from the back panel with coax and grounded it at the back panel.

The last step was to apply a bit of epoxy adhesive to the fiberglass board and the slot it runs in to hold it in place. Once the epoxy set, I did the final wiring of the front and rear panel components. You can see how I sanded the corners of the back panel in the above photo.

I connected it to my inverted L antenna and an SDR Play RSP2 and gave it a test run. I like the fact that I can visually see the changes to the signal strength on the SDR software as well as audibly. It makes a noticeable improvement to the reception.

Thank you Peter. I enjoyed the build.

Steve Allen, KZ4TN

Announcing the new SDRplay RSPdx-R2 software defined radio!

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Many thanks to SWLing Post sponsor and supporter, SDRplay, who shares the following announcement:

SDRplay announces the RSPdx-R2

SDRplay Limited is announcing the launch of the RSPdx-R2 which is an enhanced version of its highly popular multi antenna port SDR, the RSPdx.

Jon Hudson, SDRplay Sales and Marketing Director said “Global supply chain support issues have prompted some redesign of existing products to ensure continued supply for our UK manufacturing partners. With each new member of the RSP family, SDRplay tries to include improvements. This has given us the opportunity to offer performance enhancements at the same time as assuring supply”.

The RSPdx-R2 provides up to 10MHz spectrum visibility anywhere from 1kHZ to 2GHz with no gaps. It features:

Improvements to the RSPdx for MF frequencies and below:
Improved noise performance below 1MHz
Improved dynamic range below 2MHz both in tuner mode and HDR mode
3 Software selectable inputs, including a BNC input for up to 200MHz
A 500kHz LPF for LF/VLF
HDR mode for enhanced performance under 2MHz
Notch filters on all inputs
A rugged steel case

More details on https://www.sdrplay.com/rspdxR2/

The suggested retail price is £188.00 GBP (excluding VAT), $235.00 USD (excluding tax) or €225.60 EUR (excluding tax).

SDRplay recently launched their free multiplatform SDRconnect software which as well as running on Windows, will also run on MacOS and Linux/Raspberry Pi. As with their SDRuno windows software, the emphasis is on “plug and play” making the SDRplay receivers an easy-to-use and low-cost way to discover (or rediscover) the radio hobby for anyone who already uses a computer.

The UK manufactured RSP family of SDR receivers are available directly from SDRplay Ltd. or from authorised resellers worldwide. More details on https://www.sdrplay.com/purchasehome/

For more information visit the SDRplay website on www.sdrplay.com

About SDRplay:

SDRplay limited is a registered UK company, with registered offices in the UK and Ireland. UK: SDRplay Limited, 21 Lenten Street, ALTON, Hampshire, GU34 1HG, UK, Registered Number: 09035244 Ireland: The Black Church, St Mary’s Place, Co. Dublin, D07 P4AX, Ireland, Registered Number: 3591295EH Correspondence Address: PO Box 1180, Princes Risborough, HP22 9TD, United Kingdom

Video

Click here to view on YouTube.

Data Sheet

Click here to download the RSPdx-R2 Data Sheet. (PDF)

Radio Waves: The Discovery Dish Pre-Launch, China Radio International, Hackaday Prize, and Baseball Radio

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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 Ulis (K3LU) for the following tips:

Discovery Dish Pre-launch: A Lightweight Dish And Feed For L-band Weather Satellites And Hydrogen Line Reception (RTL-SDR Blog)

For the past few years we have been working on finding the best way to help beginners get started with L-band weather satellite reception and basic radio astronomy. We have now come up with a solution that we’re calling the ‘Discovery Dish’ – a lightweight 65 cm diameter dish and active filtered feed set.

The Discovery Dish will be crowd funded, and we currently have a pre-launch page set up on Crowd Supply. So if you are interested, please visit the pre-launch page and click on the Subscribe button for updates.

Discovery Dish is a 65-cm diameter aluminum satellite dish and active filtered feed designed for receiving GOES HRIT, GK-2A LRIT, FengYun LRIT, NOAA HRPT, Metop HRPT, Meteor M2 HRPT and other weather satellites that operate around 1.69 GHz. The dish is designed to weigh under one kilogram, and it splits into three petals, making it easier to ship worldwide. The 1.69 GHz feed contains a built-in LNA right at the feed point, as well as filtering, which means that there is almost no noise figure loss from cables or connectors.

Note that the prototype images show an early non-petalized prototype with rough laser cut wind holes. The production version will obviously be a lot neater looking! […]

Click here for more details about the Discovery Dish campaign.

How China’s Propaganda Infiltrated Radio Stations in Europe (The Diplomat)

State-owned China Radio International is airing its content without attribution on commercial radio stations in Europe.

China has consistently and systematically pursued the dissemination of its narratives on the global stage, with the primary aim of shaping the international landscape to align with its strategic interests and ideological perspectives. These endeavors encompass a diverse array of tactics, including the acquisition of media enterprises, active engagement by Chinese ambassadors in both mainstream and fringe media outlets, the utilization of paid supplements, collaboration with pro-Kremlin media, and the steadily expanding presence of China across various social media platforms.

Recently, China Radio International (CRI), an official Chinese state media outlet broadcasting in multiple languages, has garnered attention for its establishment of partnerships with and provision of content to radio stations worldwide. Remarkably, CRI has effectively outsourced the production of China-related programming to local partners, often without transparently disclosing the sponsorship of content creation to the listeners. This strategy, known in Chinese as “borrowing a boat to go out on the ocean,” plays a pivotal role in laundering Beijing’s propaganda and fostering the acceptance of its messaging among local audiences.

One illustrative case of this approach within Europe involves two Czech radio stations, namely Radio HEY, a nationwide commercial radio station airing rock music, and Radio Color, which positions itself as “one of the last independent radios.” From 2019 to May 2023, these radio stations broadcasted a program titled “Barevný sv?t” (Colorful World), a nearly 30-minute segment aired six times a week, with the objective of acquainting Czech listeners with Chinese culture, language, and history. [Continue reading…]

Hackaday Prize 2023: A Software-Defined Radio With Real Knobs And Switches (Hackaday)

When cheap digital TV dongles enabled radio enthusiasts to set up software defined radio (SDR) systems at almost zero cost, it caused a revolution in the amateur radio world: now anyone could tune in to any frequency, with any modulation type, by just pointing and clicking in a computer program. While this undoubtably made exploring the radio waves much more accessible, we can imagine that some people miss the feeling of manipulating physical buttons on a radio while hunting for that one faint signal in a sea of noise. If you’re one of those people, you’re in luck: [Kaushlesh C.] has built a portable, self-contained SDR system with real knobs and switches, called SDR Dock 1.0.

The heart of the system is a Raspberry Pi running GQRX, an open-source SDR program that supports many different RF modules. [Kaushlesh] used an Airspy HF+ Discovery, a compact receiver that can work the HF and VHF bands, but it’s easy to modify the SDR Dock to accept other types like those ubiquitous RTL dongles. A seven-inch LCD screen with integrated speakers forms the main output device, with everything powered by a 10,000 mAh lithium-polymer battery. [Continue reading…]