Category Archives: Guest Posts

TomL’s Guide to Audio Plugins For Radios: Part 2 – SDR Recording

Many thanks to SWLing Post contributor, TomL, who shares the following guest post. Click here to check out all of the posts in this Audio Plugin series:

Audio Plugins For Radios, Part 2 – SDR Recording

by TomL

I started investigating using the old Kenwood transceiver to send audio to my laptop and process the receive audio using VST Host for a number of functions: Noise reduction, Equalization, reduce Sibilances and fading distortion, increase presence of vocals without sounding boxy, etc. It was a qualified success depending on what VST apps I used, in what order they were used, and what settings each of them were set to. In this episode of ongoing discovery, I will attempt to show how easy it is to OVER-process the shortwave broadcast audio plus comparisons to my regular Audacity post-recording treatment.

Audio Examples

I noticed for the first time that the SDR creates a somewhat compressed file which can be seen when comparing the Waveforms of SDR vs. VST Host output files. This means that the unprocessed SDR file will always appear to sound louder because of this compression. This loss of Dynamic Range makes it harder to do the comparison. Therefore, the Audacity-only examples below are reduced 3dB or 5dB to maintain apparent loudness.

Example 1: KBS Weekend Playlist – S6-S9 signal, somewhat severe fading and moderate polar flutter.

SDR Console 3.2 using my usual NR4 set to 2dB Reduction, 30% Smoothing, and 3dB Rescale plus a Blackman-Harris-7, 5.3 kHz filter.

AUDACITY file is using my usual Audacity noise reduction:

VST version 2: Used my first set of VST apps. Sounds harsh with hash-noise and overdriven:

VST version 3: Used way too much bass, too much grunge, attenuated highs, still overdriven:

VST version 4: Using a different order to the Denoiser apps, added in Modern Exciter app, cut back on some bass but still too much, and overly forward sounding midrange:

VST version 5: My current Baseline setup. Adjusted the Denoiser apps, less extreme bass & treble, adjusted the De-Esser app, set the midrange to be less forward with just a single setting:

To my ears, Audacity processing is nice but as discovered before, sounds compressed and does not reduce some of the other problems inherent in shortwave signal fading and loss of musicality. It sounds utilitarian. Also, the noise is a bit more gnarly.

Versions 2-5 go through iterations of listening to the exact same segment over and over (and over) and trying different VST apps and settings. I think my comments are mostly accurate next to each version. However, you may think differently and perhaps prefer the sound of one of the other versions?

Example 2: Encore Classical Music, WRMI (fading S9 signal) – Audacity vs. Version 5 VST settings. VST is quieter and sounds less harsh than the Audacity version. A generally more smooth sound.

Example 3: RCI in Russian, S7-S9 with moderate polar flutter – 7kHz filter in SDR Console but VST Host is using BritPre, an analog preamp using a 6 kHz low pass filter to try to reduce DSP filter “ringing”. It shows some interesting possibilities.

Example 4: RCI in Russian – Music from the same broadcast and VST Host setup in Example 3. The screeching flute is under more control and strings more defined in the VST version.

Conclusions

I like the results of the audio processing that eventually ended up with “version 5” (plus the possibilities at 7kHz, too). It is not Earth-shattering but is an incremental improvement in my opinion (there is always room for improvement). I can use it in a simple Workflow anytime I want to record something off of the SDR. Also, I had already been using Voicemeeter Pro, a software audio mixer. It is setup with different profiles to do SDR, Ham, FM Broadcast, and now, VST Host audio routing. This process took a long time but seems satisfactory to use as a Baseline setup, which then can be tweaked slightly depending on various types of audio coming from the SDR. These changes in VST Host can be stored as their own unique profiles for audio processing.

However, a word of warning! Messing with Windows audio Sound settings and mixer software is potentially a confusing process and one can easily end up with a spaghetti-pile of conflicting connections, no audio output, doubled echo output, distortion, way too loud, way too soft, etc. If you start this experimentation, make sure to write down your current Windows Sound settings, both the Playback and the Recording settings for each item listed.

Having an SDR radio + Voicemeeter + VST Host is a very flexible setup. I can now safely say that the only thing I need Audacity for is to Normalize the peak audio to the -1 dB broadcast standard volume, which is a HUGE time saver. The SDR Console IQ files can be scheduled and processed from there at a later time. Also, the use of Voicemeeter Pro allows me to switch when to use VST Host anytime I feel like it, and Voicemeeter Pro comes with its own (manually engaged) Recorder.

Part 3 of this series will discuss Technical details for my setup. Your setup may need different settings or you may find a better way than I did. This will take some dedicated time.

Happy Listening and 73’s,

TomL

Click here to follow all of the articles in TomL’s audio plugin series.

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Imaginary shortwave stations this weekend

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Hi all, Fastradioburst23 here letting you know about a the Imaginary Stations schedule on the shortwaves this Sunday 30th July 2023. The first show will be beamed to Europe via the services of Shortwave Gold in Germany at 2000 utc on 6160 khz and will be the debut of Skybird Radio International. Expect tunes in a global style.

Then later at 2200 hrs UTC on 9395 kHz via WRMI is WSFR (Swiss Family Robinson/Lost Island Radio). Imagine you’re listening to the portable on a deserted island of your choice with all amenities provided. Tune in and let the imagination flow.

For more information on the shows email Imaginarystations (at) gmail (dot) com

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Everything is COOL on shortwave

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Hi all, Fastradioburst23 here letting you know about a couple of instances of the Imaginary Station COOL on the shortwaves this Sunday 23rd July 2023. The first show will be beamed to Europe via the services of Shortwave Gold in Germany at 2000 utc on 6160 khz.

Then later at 2200 hrs UTC on 9395 kHz the show returns in a remix form via WRMI. On both transmissions expect some cool tunes for surf, sun and summer breezes and for the shortwave spectrum of course. For more information on the shows email Imaginarystations (at) gmail (dot) com

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TomL’s Guide to Using Computer Audio PlugIns with Older Radios

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

Using Computer Audio PlugIns with Older Radios

by TomL

Older radios have a way to get audio out to speakers or another audio input device, usually just a headphone jack. Software for processing audio are plentiful and very useful tools, called VST’s. Furthermore, most Plugins were made for Musicians needing full frequency spectrum capability. I will use my Kenwood TS-590S amateur radio as a test case. I have used its speaker output to a cheap Behringer UCA-202 RCA to USB converter (it has its own volume control to keep it from overloading).

Amazon Link: Behringer UCA202

My Windows 10 Sounds Properties sees this audio as “3-USB Audio CODEC” which I have enabled on a physical USB hub with individual power switches for each port. Thanks to Steve (K1GMM) and his YouTube channel (K1GMM Green Mountain Maniac) for describing how to use Windows plugins for processing either Receive or Transmit audio. This article only focuses on Receive audio.

For my simpler needs, I have chosen to use VST Host. It will run the small “apps” that usually have a file extension of .VST or .DLL. I downloaded it right from Steve’s website:

https://kc1egu.wixsite.com/essb-ham-radio/copy-of-icom-ic7300-others

I then downloaded a number of plugins suggested by Steve on his web site (“More” Menu pulldown, DAW’s/VST DOWNLOADS). Each VST file can be copied to a central directory/folder on your computer and all read from the same place inside the VST Host. Most of these are Windows types but there are some for Linux if that is something you use. I found that VST Host does NOT like a write- protected directory, so it and the VST’s reside in my top-level Documents directory.

My resulting “chain” of VST’s process the audio from my 3-USB Audio CODEC in a sequential manner, which are:

ModernAmplifier (a Limiter to keep strong signals from overloading the processing)
ReaFir (an interesting “Subtract” feature where I cut down on the “roar” around 800-1200 Hz)
Bertom Denoiser Pro (EXCELLENT static & background noise reducer)
TDR Nova (a powerful, well-made Compessor & DynamicEQ combo)
Sennheiser-AMBEO-Orbit (a Binaural soundscape).

Once VST Host is installed, create a separate folder for the VST files. Now just copy the VST3 or DLL file for each of the apps downloaded like the ones I list above. If you have a 32-bit version of Windows, you will have to use the VST’s that are 32-bit, not 64-bit.

In VST Host, set the Wave Input and Output and sampling rate (Menu: Devices—Wave). In my case it is the aforementioned 3-USB Audio CODEC for (Microphone) Input Port and VoiceMeeter Aux-Input for the Output Port. The sampling rate is set to 48000 (You can choose Output to your “Default Speakers” which should be in the list if you do not use an extra mixer software like I do).

Now, go to Menu: File, Plugins and load each plugin that you want to use. The VST3 or DLL files should all be in the same directory that you made earlier. You may have to tell VST Host where to find them by setting the Plugin Path (Menu: File, Set Plugin Path…).

Now, once you have all the VST apps opened, you will notice that all of their individual outputs go directly to the VST Host Output. Not good, since your computer will not have enough cores to parallel-process all of these apps at the same time. So, Unchain them all by right-clicking on each app and choosing “Unchain”.

Now you will see all of the yellow connecting lines gone. Arrange (click/drag) each app in sequential order on the screen. Starting from the bottom up, right click on the app just above VST Output and choose Chain After…

Repeat up the chain, choosing the one above it to Chain After until you are left with a Daisy-Chain of apps, each output going to the Input of the next app in your desired order of processing:

Now turn on the radio to get audio going through the chain of apps. Tweaking each app is part of the tedious process of learning if an app will help or not. Just replace and Chain After in the order you want with other VST apps that you find more helpful. Tinkering with this should yield some satisfactory results if you do not overdo applying features in each app. To save the layout and VST settings, go to Menu: Performance, Save As and give it a name to store in the data file shown (just a name since it will put it into the default line 000 for you). You can choose this in future sessions from the main pulldown Menu below File. (Note: It is called “Performance” because this stuff was written for Musicians to save their home studio music along with the settings for shaping the music tracks; 99% of planet earth calls this a “Layout”, a la, Microsoft Office)

Here are two examples of sound from the radio without processing and then adding in each app over a few seconds.

LZ1AA from Bulgaria. Processing 10 secs., off 15 secs., on again 8 secs.

CHU Canada. Processing on, space, processing off. Notice a little “water” effect since AM Broadcast needs quite different settings compared to SSB Ham Radio.

You can check out Steve’s “Green Mountain Maniac” YouTube channel and see for yourself what can be done with sound processing for Radio. Some of his techniques can be used with old shortwave radio receivers as long as it has a working headphone jack or AUX Out jack:

K1GMM-RXDAP VST HOST YouTube video

Cheers and Happy Listening,

TomL

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Don Moore’s Photo Album: The Museums of Galicia

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

A Coruña coast

Don Moore’s Photo Album: The Museums of Galicia

by Don Moore

Some of my favorite sites to visit while traveling are historical, marine, and military museums. I’ve always been interested in those subjects and sometimes those kinds of museums have a few old radios on display. That makes a nice bonus to the visit. Last year, I spent May and June traveling all over Spain (with some short excursions into neighboring countries). One of my favorite regions was Galicia, where I stayed for five nights in the capital of A Coruña and six days in a rural village to the east. And the museums of Galicia had some of the most interesting radio-themed items I’ve ever seen.

Galicia is that small region of northwestern Spain directly north of Portugal. It was part of the Celtic world (along with Brittany in France and the British Isles) and the coastline was home to Phoenician and Greek settlements. It later came under Roman rule along with the rest of the Iberian Peninsula.

A Coruña Fishing Boats

A Coruña Fish Market

Spanish is spoken everywhere but the people are proud of their native language, Galician or Gallego. The language looks and sounds like Portuguese with a lot of Spanish influence but is actually older than either of those. Some linguists believe that Portuguese was derived from Galician.

The rugged Galician coast is one of the most beautiful I’ve ever seen with its numerous bays, estuaries, steep hillsides, and rocky shore. Most of Spain is arid but Galicia is one of the rainiest parts of Europe so the countryside is green and lush. And because of the neighboring cold Atlantic Ocean, temperatures remain comfortable even when the rest of Spain (and places further north) are baking in the summer heat.

A Coruña City Hall

MOON RADIO

One of the first places I visited in A Coruña was the Museo Nacional de Ciencia e Tecnología on the west side of the harbor. The very first display in the museum is a piece of radio history like no other. In the 1960s NASA set up a network of communication stations around the world to maintain constant contact with the Apollo moon missions. The primary stations were located in rural California, near Canberra in Australia, and in the little village of Fresnedillas outside Madrid. When Neil Armstrong and Buzz Aldrin landed on the moon in 1969 Madrid was facing towards them and received the first radio transmissions from the surface of the moon. This museum has one of several redundant radio racks that were used to receive that historic broadcast.

After visiting the museum I wandered uphill to Monte de San Pedro Park, the best place in A Coruña to view the city and harbor. Those heights were also once vital to the city’s defenses and the park contains several mothballed gun turrets built in the 1930s. Continue reading →

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From mountains and libraries, music connects us all

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Hi all, Fastradioburst23 here letting you know about a couple of transmissions on the shortwaves this Sunday 16th July 2023. The first show will be KNTS (Kearsarge North Transmission Service) from the Imaginary stations crew beamed to Europe via the services of Shortwave Gold in Germany at 2000 utc on 6160 khz. Expect lots of shortwave and ham related sounds and a couple of instrumentals containing CW.

Then later at 2200 hrs UTC on 9395 kHz the great Shortwave Music Library returns via WRMI. DJ Frederick digs through his across the board record collection taking a few requests, pulling out some tunes and giving them an airing over the shortwaves. Sit back and relax as it’s Shortwave Music Library time again! For more information on the shows email Imaginarystations (at) gmail (dot) com

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A review of the Radioddity RADDY RF320

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(Almost) All-in-One in a Box

By Robert Gulley K4PKM

The RADDY RF320 is a rather attractive, if not slightly curious-looking radio, which breaks from the more recent offerings from Raddy and other small portable radios. Compact, but not pocket-sized, the radio comes in at roughly 3-3/4” x 4-1/2” almost square (not counting the tuning dial on the side, the slightly raised antenna on top, or the light on the side).

The radio can receive AIR, FM, VHF, MW(AM), SW, and Weather Band signals. (For those interested in the U.S. Aircraft Band, this model does feature AM modulation, so civil aircraft can be monitored). While the radio does have AM SWL bands, there is no SSB reception. SW bands run from 90m thru 13m, with tuning in 5kHz single steps and scan mode.

This is the IOS version of the Bluetooth App. Clean layout, keyboard frequency entry and radio control

There are four tuning methods if the user includes the Apple or Android app which feature direct keyboard entry in addition to the three modes found on the radio. As a rather cool feature, the QR scan codes are imprinted on the back of the radio for both IOS and Android apps, so if you are out and about you can easily download the app to your phone or tablet. A nice touch! No having to type an esoteric web address or search for the app. (I tried both codes and they worked just fine.)

In addition to the usual tuning methods, the RF320 has what they refer to as “fine tuning knobs” on the side and front of the radio, with the knob on the side a continuous tuning within a band mode. The knob on the front is something, well, a bit unusual. While it is a fine-tuning knob, it is designed to manually tune in search mode. A little explanation is in order.

Most radios which feature a search mode, this one included, allows the user to long-press a directional button or rotate a tuning dial a given distance to activate a search mode. When the typical radio finds a station, it may stop momentarily or completely, depending on the design. The search modes in this radio all do the latter- they stop completely. However, unlike most radios, this radio features three different methods of searching. The up/down arrows can be pressed for a second or two to start a search, or the tuning knob on the side can be rotated some distance quickly, and a search will begin. The third method is the tuning knob on the front. By manually turning the knob the radio will attempt to find the next signal within the current band or sub-band without stepping through each 5kHz frequency (of course it is doing this internally, but it is not really obvious visually).

For example, when in FM mode, this tuning method will jump to the next usable station. In SW mode, in a given sub-band (13m, 90m etc.), this knob will jump to what it senses as the next usable signal, rather than scanning every 5 kHz as done in the other modes. This allows for a very quick check of a given band (or sub-band).

As with any search mode on a radio like this, there will be false positives. Life is not fair – static crashes and birdies and digital signals can all fool a radio’s search mode.

Changing lights, Bass Boost, and QR Codes for Downloading Android or IOS Apps

The radio features excellent sound for its size, with a rather large front-facing 5W speaker, and a bass port on the back. I can crank the volume louder than I would ever want in a room and the audio remains clear.

Reception on all the bands is quite acceptable, keeping up with typical portables its size, and even ones with longer antennas and larger ferrite bars for AM reception. This is not a Panasonic RF-2200 or a GE Superadio, but for what it is designed to do, it does quite well.

The radio also has an abundance of memories, allowing you to save up to 995 stations, including 199 each for AIR, FM, VHF, MW, and SW.

Like some of the other radios from RADDY, this one has Bluetooth connectivity to Android or IOS for the App functionality, and takes a TF memory card to allow for playing music, podcasts etc., as well as having a flashlight and S.O.S. capability. There is a headphone jack and Aux. jack, as well as a USB-C charging port for the replaceable 18650 2000mAh battery (whoo-hoo!). Sleep mode, timer, wake to music and six sound effects are added features.

Lights, lights, and more lights. ‘Nuff said! (See images)

Pros and Cons

Pros: Good audio, AM receive for aircraft band, good sensitivity, multiple ways to tune, excellent App connectivity on my iPhone with direct frequency entry, good form factor, unit seems solid, replaceable battery, 18-month warranty(!), carry strap, aux. input to allow the radio to act as a speaker, included wire antenna and charging cable.

Cons: Telescoping antenna a bit frail, side tuning knob feels a bit wobbly (but I experienced no problems), back colored lights seem unnecessary (nit-picking and just a personal opinion, YMMV), EQ effects seem weak as only a few seem to make much of a difference (and not needed in my opinion, since the standard audio is quite good), no SSB (not a problem for me but will be a deal-breaker for some), and typical for this type of radio soft muting while tuning.

Conclusion

This is a good, solid radio with lots of options in terms of modes and bands, as well as extras which make it an almost all-in-one radio. This is a radio one could take to the beach or a park, or use in an office or on the coffee table or night stand. It is small, portable, packed with features, and controllable from your phone or tablet. At a price well under $100 ($71.99 special price from Radioddity at the time of publication), this may well be the radio you have been looking for to fill that portable niche!

Note: Using this link to purchase the Raddy RF320 will include a $15 discount for you and a small commission to the SWLing Post.

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