Shortwave listening and everything radio including reviews, broadcasting, ham radio, field operation, DXing, maker kits, travel, emergency gear, events, and more
Today is Sunday July 4, 2021. Besides being Independence Day here in the States, it’s also Alexanderson Day in Sweden!
This morning, I discovered a video on the Grimeton Station YouTube channel: a recording of their live stream live stream starting around 08:30 UTC today.
In the video, you can watch the crew of the Grimeton station startup, tune, and transmit on their 1924 Alexanderson Alternator with the callsign SAQ. Their message is sent in CW on 17.2 kHz. The video is absolutely fascinating and I highly recommend watching it. The startup and tuning procedure are simply amazing. I can only imagine the dedication and resources it takes to keep this marvel of 1920s engineering fully functional today:
We’ve been continuing to write your QSL cards and we’re now sending them within 2 months of receipt of your emails!
Just like the last few months, we’ve split the broadcasts into 3 versions;
• WRMI & On-Demand Version: RNEI 19 + RNEIxtra (Mammas Mest Metal & Stephen’s feature) + HamDRM.
• Channel 292 & Radio Onda version: RNEI 19 + HamDRM + This is an Express Music Show.
• World FM version: RNEI 19 only.
RNEI #19 is packed full of great music including:
• The show starting with some Icelandic Rock
• Cindy Chiche
• A really pretty song from Døssi
• Spooky vibes in our traditional pick from Gyda
• Scandipop.co.uk‘s fantastic song of the month that has some Sámi Lyrics!
• Some MFSK64 embedded in two parts of our dance mix at the end of the dance mix!
The 4th show of Mamma’s Mest Metal will bring some amazing symphonic metal this month, it’s an amazing genre and some of Mamma’s picks this month are fantastic!
Stephen is bringing us a feature on the Scottish artist Julie Fowlis with some really beautiful songs and, lastly, YH brings us another fantastic episode of This is an Express Music Show.
Daz has coded some HamDRM data for you to have a go at decoding too!
You can use EasyDRF, Easypal & WinDRM on Windows (or Wine in Linux) and QSSTV & TRXAMADRM on Linux. We recommend against Easypal due to some security flaws we’ve noticed and WinDRM because it’s an older version of EasyDRF.
We have found that 158° has a good signal in South Eastern and Northern Europe, 80° has a signal in Brazil and surrounding areas as well as Portugal & Spain and 332° is good between Ukraine and Italy. These happen because there is some backbeam with these directional antennas so give them a go and see what happens!
Also keep an eye on our announcements for extra broadcasts!
If you miss the show you can always catch up on demand and, if you prefer to only hear our music, we have Spotify Playlists of each show usually published after the first broadcast!
Lab599 have informed me that Nevada Radio will be the exclusive distributor of the TX-500 in the UK.
In addition, Waters and Stanton will be a TX-500 dealer and distrubutor.
The price will be £899 and both retailers are taking deposits (Nevada a £83.33 deposit, Waters and Stanton a £100 deposit) for the first delivery due in September 2021.
Many thanks to SWLing Post contributor, Paul, who recently shared a link to this Craigslist listing and asked if anyone in the SWLing Post community might be familiar with this Beam Box Electronically Directable FM Antenna.
The Cragslist post actually included the following images of the owner’s manual:
I’ll admit that I’m not at all familiar with this antenna, but I see how it might have been ideal for a component system. I’m curious if it was FM DX-worthy!
Many thanks to SWLing Post contributor, TomL, who shares the following guest post:
Recording Music on Shortwave Part 2 – Weak signal recovery
by TomL
The QRM noise cloud surrounding my condominium motivated my first foray into noise reduction software to find a little relief (Please refer to Part 1 posted here) using SDR recordings. I was able to use the freeware software Audacity to reduce some of that type of noise to tolerable levels on strong broadcasts. But what about non-condo noise, like out in the field??
NHK Japan
I took my trusty Loop On Ground antenna to the usual county park Forest Preserve which is relatively low in RF noise. I did some usual recording on 25 meters and poked around for something being captured by SDR Console. On 11910 kHz is NHK broadcasting daily from Koga, Japan. It is hearable at this location but is always an S7 or weaker signal despite its 300 KW of power no doubt due to being beamed away from the Midwest USA.
I recorded it using the SDR Console 10kHz bandwidth filter and created a separate noise recording from a nearby empty frequency. Here is the 2 minute portion of a Japanese music teacher. No noise reduction was applied:
I opened the noise and broadcast recordings in Audacity to see what I could do. Part 1 of my previously mentioned post details how I apply the Noise file. A big downside of using any kind of noise reduction software is that it is ridiculously easy to destroy the desirable characteristics of the original recording. Applying too much noise reduction, especially in the presence of constant, spiky lightning noises, will create both digital artifacts as well as very dull sounding results. So I used the Effect – Noise Reduction (NR) feature very carefully.
In this example, I used the Effect – Amplify feature on the one minute noise file. I applied just +1dB of Amplify to the whole file. Then I highlighted a 10 second section I thought was representative of the general background noise and chose Edit – Copy. Then, I opened the broadcast file, Pasted the 10 seconds of noise to the END of the file and highlighted just the 10 seconds of noise. Then I chose Effect – Noise Reduction – Get Noise Profile button. Amplifying the noise file by +1db does not sound like much but it seems to help according to my tests. Anymore than this and the Noise Profile would not recognize the noise without destroying the music.
I used the NR feature three times in succession using the following (NoiseReduction/Sensitivity/FrequencySmoothing) settings: Pass1 (3dB/0.79/1), Pass2 (2dB/1.28/1), Pass3 (1dB/2.05/0). Part of what I listened for was choosing the Residue circle and Preview button for any music or dialog that was being filtered out. If I heard something that came from the desired part of the recording in Residue, I knew that I hit the limit concerning the combination of Noise reduction and Sensitivity settings to engage. I used those Residue & Preview buttons over and over again with different settings to make sure I wasn’t getting rid of anything wanted. I also used the higher Noise reduction with lower Sensitivity to try to get rid of any momentary spiky type noise that is often associated with SWLing.
I messed around with a lot of test outputs of differing dB and Sensitivities and a lot seemed to depend on the strength of the broadcast signal compared to the noise. If the broadcast was weak, I could push the dB and Sensitivities a little harder. I also noted that with strong signal broadcasts, I could NOT use more than 1 dB of Noise reduction beyond a Sensitivity of about 0.85 without causing damage to the musical fidelity. This was a pretty low level of nuanced manipulation. Because of these minor level Audacity software settings, it dawned on me that it is very helpful to already be using a low-noise antenna design.
If the Sensitivity numbers look familiar, that is because I tried basing the series of Sensitivity on Fibonacci numbers 0.618 and 0.786. Don’t ask me why these type of numbers, they just ended up sounding better to me. I also needed a structured approach compared to just using random numbers! Probably any other similarly spaced Sensitivity numbers would work just fine, too.
Now if you really want to go crazy with this, add Pseudo Stereo to your favorite version of this file (also detailed in Part 1) and playback the file using VLC Media Player. That software has a couple of interesting features such as an Equalizer and a Stereo Widener. You may or may not like using these features but sometimes it helps with intelligibility of the voice and/or music [VLC will also let you right-click a folder of music and choose to play all it finds there without having to import each MP3 file into a special “Library” of music tracks where they bombard you with advertisements].
You can also turn on Windows Sonic for Headphones if you are using the Windows operating system. However, this can sometimes be too much audio manipulation for my tastes!
Here is the resulting NHK noise-reduced file with 9ms of delay with High & Low Filters:
Radio Thailand
Five days later I was out in the field again. This time I found Radio Thailand on 11920 kHz finishing up a Thai broadcast. It was a weaker S5 signal than the NHK example, so it would be a good test.
When I got home, I recorded the broadcast file at a Bandwidth filter of 8 kHz and using Slow AGC and the extra Noise file at 12kHz using Fast AGC. In a previous test I had noticed a very slight improvement in sound quality in the way noise seems to get out of the way quicker compared to Slow AGC (which is usually how I listen to shortwave broadcasters). I now try to remember to record the Noise file with Fast AGC.
Here is the original without any noise reduction:
This time the Noise file using Amplify +1dB did not help and I used it as-is for the 10 second Noise Profile. I then tried multiple passes of NR at higher and higher Sensitivities and ended up with these settings the best: Pass1 (1dB/0.79/0), Pass2 (1dB/1.27/0), Pass3 (1dB/2.05/0), Pass4 (1dB/3.33/0).
As a comparison, I tried recording only with SDR Console’s noise reduction NR1 set to 3dB and got this. I hear more noise and less of the music coming through:
Now for more crazy Pseudo Stereo to finish up the Audacity 4Pass version (nice Interval Signal of Buddhist bells ringing and station ID at the very end):
Summary
I do not understand why applying 3 or 4 separate 1dB Sensitivities of noise reduction is superior to just one Pass at 3dB Sensitivity (in Audacity) or the one 3dB noise reduction (in SDR Console). My guess is that doing 1 dB at different Sensitivities shaves off some spiky noise a little at a time, somehow allowing for more of the musical notes to poke through the noise cloud. Who knows but I can hear a difference in subtle musical notes and sharpness of voice and instruments. Probably the Fast AGC helps too.
Music is a Universal Language that we can share even when we don’t understand a word they are saying. And there is more music on the air than I thought. Some of these recordings sound surprisingly pleasing after noise reduction. The fake stereo is pumped through a CCrane FM Transmitter to a few radios in the home, or I can use the Beyerdynamic DT990 Pro headphones.
While some SWLs and radio listeners dislike Web-based SDRs because they don’t feel like “real radio” there’s no denying that they do offer up listening opportunities you might not otherwise be able to enjoy from home.
Case in Point
Friend and SWLing Post contributor, Pete Madtone, has been enjoying dropping in on a local Slow Morse Morning Club via the G0XBU WebSDR. He’s shared a bit of recorded audio with me in the past, but this morning he sent me a link to the SDR with the frequency of the class in progress.
We both listened live with Pete and the repeater in the UK, and me in the States.
The class is wonderful and what I consider an ideal use of local repeaters. Linda serves up a sentence of slow code, then reads back what she sent. The others on the repeater then chime in with their copy–what they copied and what they missed. There really is no better way to build up your CW chops in the beginning than to do this–it’s interactive, supportive, and the audio very clear via FM on the repeater. It’s proper distance instruction using my favorite medium: radio!
Plus, well, the whole thing has some serious charm. I started an audio recording of the class this morning. Here’s it is for your enjoyment:
Many thanks to SWLing Post contributor, Pete Madtone, who shares the following announcement:
This Sunday4th July 2021Free Radio Skybird is being beamed out of the WRMI transmitter from Miami on 9395 kHz at 2300 utc (12 midnight UK time). Expect some free radio goodness from DJ Frederick and the Free Radio Skybird crew. Tune in here on Sunday if you’ve no shortwave radio.
Spread the radio love
Please support this website by adding us to your whitelist in your ad blocker. Ads are what helps us bring you premium content! Thank you!