Category Archives: Mediumwave

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

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.

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.

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

Preserving Radio History in Your Community

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Many thanks to SWLing Post contributor Dan Greenall, who writes:

I have lived in southern Ontario, Canada my entire life, have been DXing since the late 1960’s and have held the amateur radio call sign VE3HLC for over 50 years. Most of this area’s AM broadcast stations had been considered “pests” over the years as I searched for more distant targets, until recently, when many of these began quietly slipping from the airwaves. While this opened up some new frequencies to DX, I soon began to feel that I had lost some old friends, many that I had known since childhood.

When I retired in 2018, I decided to spend a little time trying to preserve some radio history of stations in southern Ontario communities that have played a part in my life. This might include audio clips, QSLs, station booklets, and other types of ephemera, and I would try to place this information where it could be easily accessed by future historians or anyone else who is interested. In the end, I chose to use the Internet Archive (archive.org), where most uploaded information can be viewed (or heard) and downloaded for free.

CFPL, London, Ontario 980 kHz (still on the air)

“Communications in the Community” is a hardcover limited edition (2000 copies) souvenir book printed in 1966 by the Special Printing Unit of The London Free Press in London, Ontario, Canada. It includes historical information about the London Free Press (newspaper) and CFPL radio and television. I was lucky to find this item at a church rummage sale nearly 20 years ago.

CFPL began its life as CJGC in 1922. I acquired one of their QSL cards from 1925 through an eBay purchase a few years ago.

The above and more can be found by clicking on this link.

https://archive.org/details/page-16

CKOC, Hamilton, Ontario 1150 kHz (still on the air)

CKOC radio in Hamilton also started up in 1922. My parents met while working at the station in the late 1940’s. My brother and I (both radio amateurs), along with a few friends were given permission to operate on “Field Day” weekend in 1985 from their old abandoned transmitter site at Elfrida, Ontario.

This area has long since been developed to build homes and shopping areas.

“This is Hamilton, Ontario and the story of broadcasting station CKOC” is an undated booklet (I am guessing circa 1950) that I was able to purchase on eBay. Also found on eBay were two verifications, one from 1931 and the other from 1983.

You can find these scans and more by following this link.

https://archive.org/details/page-13_202209

CKNX, Wingham, Ontario 920 kHz (still on the air)

This station began in 1926 using the unusual call sign 10BP. It would remain that way until 1935. I managed to secure this QSL from 1932 through eBay, signed by its founder W.T. “Doc” Cruickshank.

Interesting stories of how the station began can be found at this link.

https://www.communitystories.ca/v1/pm_v2.php?id=story_line&lg=English&fl=0&ex=386&sl=2541&pos=1&pf=1

CKCR, Kitchener-Waterloo, Ontario 1510 kHz (no longer on the air)

In 1924, this station began briefly in nearby Brantford, Ontario. It quickly moved to Kitchener-Waterloo and existed until 1965 when it became CKGL. The CKCR call sign was picked up later in 1965 by a station in Revelstoke, BC.

Another eBay purchase, I found this QSL with a not-to-scale map of southern Ontario from 1934.

More Ontario QSL’s can be found in my broadcast band gallery at this link: https://archive.org/details/ckoc-hamilton-on-1983

I would encourage others to save parts of the local radio history in their city, state, province or country and give back to the hobby that we have enjoyed for so many years. I would also be happy to hear about any efforts you have made!

Dan Unearths Radio Memories: A 1990s Treasure Trove of Broadcast Ephemera

1 Reply

Many thanks to SWLing Post contributor Dan Greenall, who writes:

Hi Thomas

Before the days of the internet and e-mail, handwritten or typed reception reports mailed out to broadcast stations would often net the lucky DXer other goodies, including station brochures, program schedules, frequency guides, station stickers, blank reception report forms, pennants, booklets, and other items in addition to that coveted QSL verification.

The QSLs were stored carefully away in albums or shoe boxes, while much of the other paper ephemera eventually (over the years) made its way into a recycle bin. Recently, while cleaning out some storage boxes in the basement, I came across a number of envelopes containing some of the aforementioned items from the early to mid-1990s. To preserve these newly discovered pieces of radio history, I have scanned much of the material and included it here.

Here’s a sampling: