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Many thanks to SWLing Post contributor Scott Gamble, who writes:
Hi Thomas –
An interesting article was published in the most recent issue of Inside GNSS magazine that suggests that the US Military has been using an obscure field in GPS broadcasts to deliver encoded messages, potentially for use by intelligence agencies.
The article “The Empty Field That Wasn’t: GPS, OTAD, and Two Decades of Encrypted Messages,” by Steven J. Murdoch of University College London, is available via the link below:
Many thanks to SWLing Post contributor Dennis Dura, who shares the following article from Radio World about the impending shutdown of Canada’s iconic CHU shortwave time station.
We’ve covered CHU’s imminent closure several times here on the SWLing Post, but this Radio World piece provides a particularly nice overview of the station’s history, purpose, and enduring significance to the radio community. It’s well worth a read, especially if CHU has ever been one of those familiar signals on your dial.
Hi to all SWLing Post community. Here’s news of what Imaginary Stations will be bringing to those shortwave bands this week.
We have the fourth programme in the Downbeat on Shortwave series via Shortwave Gold, where guest DJs Jesse Yuen and One Deck Pete bring you two 15-minute downtempo mixes each over the hour-long show. Expect some ambient, dub and downtempo vibes to wind down to at the weekend. The schedule for the show is on Saturday 13th June at 1100 hrs UTC on 6160 kHz and then again on Sunday 14th June at 1300 hrs UTC on 6160 kHz and 2000 hrs UTC on 3975 kHz/6160 kHz. Listening while horizontal is an option.
On Wednesday June 17th at 2000 hrs UTC on 3975 kHz/6160 kHz we bring you the repeat of last week’s Skybird Folk & Country Radio. If you’re into both those genres you are going to love this show if you didn’t catch it last week
Also on Wednesday 17th June 2026, at 0200 hrs UTC on 9395 kHz on WRMI we have WHFM – Herman’s Radio and Record Room. This is the third in a series of programmes recorded by DJ Frederick Moe in memory of his father Herman (1919-2001) and feature mid-century sounds including country, jazz, folk and easy listening.
For more information on all our shows, please write to us at [email protected] and check out our old shows at our Mixcloud page here.
Reading through the 1971 World Radio-TV Handbook only as a reference source was interesting, but as I started listening more I also realized I felt part of what was happening – I could hear many of the countries described, one way or another.
I’ve always liked directories. You can often learn more of what’s happening than you can in a textbook.
The 25th edition of the directory of international radio and television was published in 1971 in English in Hvidovre, Denmark, and printed in Great Britain.
Looking at the information, organized by continent and country, you discovered that most European countries had a domestic network of AM and FM stations, including some very high-powered AM stations, along with domestic shortwave services and a full complement of what were called foreign services, the international broadcasts.
In Africa, many listeners got their news from domestic shortwave broadcasters and some AM stations. In 1971, FM had not penetrated Africa except in a few places. Likewise, Asia had few FM broadcasters outside of Japan and a few other countries. All domestic broadcasts in Indonesia, for example, were on shortwave, there was no AM broadcasting at that time.
I counted almost 75 advertisers in the 1971 WRTH, including many shortwave stations and makers of professional recording and studio equipment.
Advertisers included Radio Moscow, Shure stereo cartridges, Voice of America, Radio RSA from South Africa, Radio Sweden, Continental Electronics, Hallicrafters, a Chicago area maker of shortwave radios, and Hammarlund Mfg. Co., a maker of top-line receivers.
WRTH also had the music signature and description of the interval signal for dozens of stations.
The United States listing in WRTH had only AM mediumwave stations with more than 10 kW, and no FM stations listed. Also included were Voice of America, and shortwave stations AFRTS, KGEI, WNYW, and WINB.
Central and South America still had a bounty of mediumwave and shortwave stations, including many smaller private stations
More than 23 countries were listed with DX programs. WRTH also listed time signal stations (almost every major country had one) and programs in Esperanto. TV had not achieved widespread coverage in many areas, although most countries had at least a few over-the-air channels.
I should mention two other publications from 1971, both well-written and informative. The first issue of Communications World in 1971, from Davis Publications, was written by Don Jensen and was a great introduction to the hobby. That same year, Communications Handbook, published by Popular Electronics, came out, with a mediumwave and shortwave DXing overview written by Richard Wood that also featured very good descriptive writing and information.
Karl D. Forth has been interested in radio and DXing for more than 50 years. This story was included in the book Radio Nights and Distant Signals.
Karl D. Forth has been interested in radio and DXing for more than 50 years. This story was included in the book Radio Nights and Distant Signals.
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Many thanks to SWLing Post contributor, Paul Jamet, who shares the following announcement:
24 Hours of Le Mans 2026
During the legendary 24 Hours of Le Mans Automobile race, the amateur radio operators of the Sarthe Radio Club F6KFI will be in the spotlight!
To celebrate the legendary 24 Hours of Le Mans, the amateur radio operators of the Sarthe Radio Club F6KFI will be in the spotlight!
From May 30th to June 14th, 2026, they will be activating the special callsign TM24H.
Operations will be available on numerous bands and modes:
SSB
CW
RTTY
PSK
FT8
VHF & QO-100
A great opportunity for all radio enthusiasts to connect with this special activation and celebrate one of the world’s greatest motorsport events together!
Following up on the article I recently wrote about the MLite-880, I still had a comparison with a reference radio on a proper antenna on my to-do list. I wasn’t in a hurry because I got pretty fascinated with exploring what I can get out of various magmounts on my car with this radio, which is quite a lot and it never gave me the feeling of missing out on something. I was also a bit hung up on the idea of comparing the MLite with the Belka because, you know, same price level and all, but that’s a bit iffy with my little passive splitter and 2 different input impedances.
Then a claim was made on the interwebz that the MLite-880 would be just a mediocre radio that would not stand scrutiny without its outstanding noise reduction, to summarize that in my own words. My experience is obviously very different and it made me curious how much truth could be in this claim. So I just took the ingenious Icom and the mediocre MLite to the dike to slip in a little shootout and then maybe give the loser a Viking funeral on a little raft I improvised out of flotsam and jetsam while making a lot of recordings to give my findings a whiff of evidence.
Both radios were connected to my lazy 10m/33′ monopole antenna via a Diamond SS-500 splitter and 15m double-shielded and common-mode choked coax. Both were recording to their own SD cards, but unfortunately, the recorded audio from the Icom does not represent the live audio off the radio on AM recordings because it records to an SD card with an 8 kHz sample rate, and that limits the audio bandwidth to at best 4 kHz. The deciding thing to listen to in these recordings is the noise and sometimes the pure existence of a signal, though, and lower bandwidth is almost an advantage in this context.
oznorWO
Sensitivity Test
Since the question is really the practical sensitivity and, therefore, how dependent this radio is on its noise reduction to get good results, I’ll start with the IBP beacons, which were recorded without NR, of course. To spot and quantify SNR/sensitivity differences you can use the four -10dB stepped (100W, 10W, 1W, 0.1W) dashes the IBP beacons transmit after their callsign.
The most grassrootsy first: OA4B in Peru (10,800km/6,700mi) on the 17m-band. MLite first, then the Icom. Both radios receive the second (10W) dash as faintly as the 100W dash, but with too little SNR left.
5Z4B beacon in Nairobi, Kenya (6,600km/4,100mi with a 3rd dash = 1W!) informing a silent 15m band about the opportunity around sunset. MLite starts again, then the Icom. The latter has the 3rd dash faintly but clearly and the former leaves some more ambiguity about that. Demonstrates again the minuscule difference.
5Z4B again, but on 20m with a 4th dash to count, whether or not the last one is really from 5Z4B or just interference doesn’t matter; what counts is that both radios heard it. The 1W dash was clearly received by both, starting with the MLite.
Here’s one where only the MLite heard an interference, and I’m not sure it imagined it (absolutely unavoidable pun) – VK6RBP in Australia for the 10,000 miles bragging rights.
I think the conclusion here is that we could probably agree on “same ballpark”, right? I don’t know about you, but imagine my surprised Pikachu face!
The AF SNR difference, which is probably all that counts in sensitivity tests, is within 3dB between the two, not to be confused with RF power decibels (but reflected on the RF side in comparably small amounts). For the interested:I did take day/night variations of the noise floor above 10MHz into consideration, with a decreased noise level around midnight on 21MHz, the MLite still matches the Icom, which is all that counts in this comparison (not absolute measurements) context.
The magic button
Another claim was made about the noise reduction, that it would only work with signals of a certain strength. While it is technically correct that it needs a minimum SNR to improve upon, my experience is that it is effective with almost any remaining SNR, provided the signal is fed into the NR with sufficient levels, and it exceeds all my expectations at that. Here are a few recordings of CHU demonstrating both points:
CHU 14670 kHz in Ottawa (5,800km/3,600mi) in bad enough conditions. The same announcement from the IC-705, then the MLite with NR at ? of its range. Note how difficult the French announcement at the end of the transmission is for both radios. I will miss that station. The noise, not so much.
This is just the announcement a minute earlier, when the signal dipped below the noise floor. Nothing gets really recovered, but nothing gets lost either, and what’s left stands out more:
However, if you only look at its inability to cheat physics, you could be missing the point of a good noise reduction in this particular “shortwave radio” context. Restoring fidelity, removing masking noises and generally increasing the SNR and thus ease of listening is having a massive impact on how at least I can enjoy programs or conversations and there’s more: After a few decades many of us (particularly 2-way) radioheads have gotten their auditory cortices hardwired to make a connection between noise and signal strength and then pushing this NR button might feel like witchcraft when it makes a bloke driving around on the other side of the globe sound like he’s just passing your local highway intersection.
In the following sound clips you will hear both radios taking turns in 5-second chunks as if I switch forth and back between them, in some of them I will play the same bit of transmission twice, first from the one, then the other radio so you can e.g. make out differences quite precisely. Continue reading →
