Shortwave listening and everything radio including reviews, broadcasting, ham radio, field operation, DXing, maker kits, travel, emergency gear, events, and more
SigDigger is a graphical, digital signal analyzer I wrote in Qt5 for Unix systems like GNU/Linux or MacOS. Unlike existing alternatives, SigDigger is not based on GNU Radio. Instead, it uses its own DSP library (sigutils) and a realtime signal analysis library (Suscan) that exploits multicore CPUs to distribute load. Also, SigDigger supports most SDR devices in the market thanks to SoapySDR. Sigutils, Suscan and SigDigger are software libre, licensed under the terms of the General Public License version 3.
[…]SigDigger works in x86-64 CPUs running MacOS or GNU/Linux. In terms of performance, it can beat Gqrx by a factor of 20% (measured as saved CPU usage).
There are plans to port SigDigger to additional operating systems and architectures. Both Suscan and Sigutils have been successfully built and run in armhf Linuxes (i.e. Raspberry Pi) in the past, but official support is on its way.[…]
Current features
MacOS & GNU/Linux support.
Both realtime and replay analysis modes
Analog mono audio playback (AM, FM, LSB and USB)
Baseband recording (full spectrum and per-channel)
Per-device gain presents
Dynamic spectrum browsing
ASK, FSK and PSK inspection
Gradient-descent SNR calculation
Different spectrum sources (cyclostarionary analysis, signal power…)
Symbol recording and visualization
Doppler analysis
Filename-based raw file parameter guessing
Transition analysis
Interactive Panoramic Spectrum view
Waveform inspection window, including burst detection and limited off-line demodulation support
Signal source decimation
Bandplan information
Audio channel recorder
Blind parameter estimation
Network broadcast of demodulated channel
UDP broadcast of received samples and demodulated symbols
Spectrum integrator (for radioastronomy enthusiasts like me!)
Check out SigDigger’s Github page for full build instructions and pre-compiled binary release links.
Many thanks to SWLing Post contributor, Paul Evans, who shares this article from Hackaday that highlights a crystal radio built completely on a smart chip credit card by Billy Cheung.
This is possible because the smart chip on many credit cards contains a diode. It’s then a simple matter of hooking up the right pads on the credit card to the rest of a crystal radio circuit, and you’re all set. Of course, [Billy] goes the whole hog, building the entire radio on a single credit card. Other cards are cut up to create bobbins for winding coils to form a variable inductor, used to tune the radio. Doing this allows for a much cleaner, thinner design, rather than using a variable capacitor which is comparatively hard to find. Turning the dial allows stations to be tuned in, and with a high impedance earbud hooked up, you’re listening to AM radio. Oh, and don’t forget an antenna!
Cheung documented the whole process and even shares templates via links in the description of his YouTube video.
Many thanks to Paul and Hackaday for sharing this fun project!
From the Isle of Music, June 7-13:
This week, special guest Rodrigo García helps us present Ceda el Paso’s innovative new jazz fusion album Te estoy llamando. In the second half, we listen to part of a new tribute to Orquesta Aragon’s 80 years by Maraca, Orquesta Aragón and others.
The broadcasts take place:
1. For Eastern Europe but audible well beyond the target area in most of the Eastern Hemisphere (including parts of East Asia and Oceania) with 100Kw, Sunday 1500-1600 UTC on SpaceLine, 9400 KHz, from Sofia, Bulgaria (1800-1900 MSK)
If you don’t have a shortwave radio or are out of range, you can listen live to an uplink from a listening radio in the Netherlands during the broadcast at
http://websdr.ewi.utwente.nl:8901/?tune=9400am
2. For the Americas and parts of Europe, Tuesday 0000-0100 on WBCQ, 7490 KHz from Monticello, ME, USA (Monday 8-9PM EST in the US).
If you don’t have a shortwave or are out of range, you can listen to a live stream from the WBCQ website here (choose 7490): http://www.wbcq.com/?page_id=7
3 & 4. For Europe and sometimes beyond, Tuesday 1900-2000 UTC and Saturday 1200-1300 UTC on Channel 292, 6070 KHz from Rohrbach, Germany.
If you don’t have a shortwave radio or are out of range, you can listen live to uplinks from various websdrs in Europe.
Our Facebook page is https://www.facebook.com/fromtheisleofmusic/
Our Patreon page is https://www.patreon.com/tilford
Uncle Bill’s Melting Pot, June 7 and 9:
Episode 168 honors guitarist and cofounder of Malo, Jorge Santana, who passed away in May, with an hour of music from Malo’s early recordings.
The transmissions take place:
1.Sundays 2200-2300 (6:00PM -7:00PM Eastern US) on WBCQ The Planet 7490 KHz from the US to the Americas and parts of Europe
If you don’t have a shortwave or are out of range, you can listen to a live stream from the WBCQ website here (choose 7490): http://www.wbcq.com/?page_id=7
2. Tuesdays 2000-2100 UTC on Channel 292, 6070 KHz from Rohrbach, Germany for Europe.
If you don’t have a shortwave radio or are out of range, you can listen live to an uplink from different web SDRs in Europe
including a live uplink from a listening radio in the Netherlands at http://websdr.ewi.utwente.nl:8901/?tune=6070am
Our Facebook page is https://www.facebook.com/UncleBillsMeltingPot/
Our Patreon page is https://www.patreon.com/tilford
Radio Waves: Stories Making Waves in the World of Radio
Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers. To that end: Welcome to the SWLing Post’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!
Many thanks to SWLing Post contributors Tracy Wood, Michael Bird, and David Shannon for the following tips:
Over the last century, radio stations have been the subject and the setting for a number of TV shows and movies. This, for better or worse, is how the general public perceives how real-life radio works. I’ve rated this selection of radio-centric shows and scenes through the years.
1. WKRP in Cincinnati (1978-1982)
Authenticity Rating: 3/5
Every time people of a certain age hear that I work in radio, they inevitably ask “Is it anything like WKRP?” The answer is both yes and no.
The show’s creator, Hugh Wilson, did come from a radio background, serving time as a sales rep at WQXI, a top 40 station in Atlanta, so he was certainly well qualified. His characters were slight caricatures of the real thing: the general manager who was often clueless about what was happening with his station; the harried program director; the burnout morning man; the trippy nighttime DJ; the sleazy salesperson; the squirrely newsman; the naive copywriter; and the receptionist who secretly runs the place. I’ve worked with each of those people multiple times.
The show was groundbreaking in its use of music. Up until WKRP came along, no one used real music in the soundtrack. It was all stock stuff, soundalike material made up by studio players. But viewers of WKRP heard actual songs from bands they recognized — something that eventually created endless licensing headaches when it came to syndication and issuing the show on DVD. That remains the reason why the show isn’t streamed anywhere. (Hugh Wilson explains the music issues here.)[…]
According to a new survey, 76% of Australians oppose any further cuts to the ABC’s budget and 49% believe it should get more Federal Government funding
The findings of a Roy Morgan national opinion poll serve as a warning to the Government that voters have had enough of budget cuts to the national broadcaster. Successive Governments have reduced ABC funding by a total of $783 million since 2014.
The survey shows Australians overwhelmingly turn to the ABC in times of crisis, underlining the national broadcaster’s critical role in the bushfire crisis and the COVID-19 pandemic. ABC Friends commissioned the opinion poll, which was carried out by the independent research group, Roy Morgan.[…]
Fictional novels about number stations have been created in the minds of most people. Many people think of the number station as a ghostly, creepy, mysterious or supernatural symbolic message. But are the messages fictional novel about numbers stations at the number station really mysterious? In today’s discussion we will know what number station is and why somebody finds it fictional novel about number station?
We all listen to the radio more or less. There are basically two types of radio listeners, such as FM radio stations and radio stations broadcast from the Internet. There are also radio stations of other frequencies and their different names. Such as high frequency or shortwave, extra high frequency, ultra high frequency limit through which there is also satellite signal and police scanner report.
Amateur radio, pelagic and air stir are also included in these frequencies. Today we will learn about high frequency i.e. shortwave radio station which is also known as fictional about number station. This number is used to send symbolic messages to various intelligence agencies and the military. This number station has been in found since the First World War and has been the center of attraction for many years. For many years some of journalists have tried to decipher the mystery of this number station.[…]
A teenager who restores and repairs old radios says he loves the “unexplained charm” and history of the wireless.
Diogo Martins, from Oadby, Leicestershire, has been able to spend more time on his hobby during the coronavirus lockdown and has added to his collection of vintage radios.
“Without a doubt many of these radios have a family history where families have gathered around to listen to music and information, and it’s that history which I find so endearing,” he said.
The 19-year-old electrical engineering student said in restoring them he is “continuing their legacy”.
Today, we learned of the site’s closure. Here’s the message posted at SDR.hu:
The SDR.hu project has been finished
I’d like to say a big thanks to everyone who joined my journey with this project!
I hope you had a good time listening on the site, and learnt some things about SDR. The purpose of this site was to provide a technological demonstration for amateur radio operators about Software Defined Radio, and I hope this goal has been reached. As this website was a one-person hobby project, with my tasks and responsibilities growing, and my focus moving to other projects at which I hope to make a greater positive impact, I’m unable to further develop SDR.hu and protect it from abuse.
Furthermore, I think this site has some good alternatives now. Nevertheless, in my opinion amateur radio receivers should be shared with strict access control in the future.
If you have more questions, feel free to consult the FAQ.
73!
Andras, HA7ILM
SWLing Post contributor, Mark Fahey, shared the following message sent by Andras to all KiwiSDR owners in the database this morning:
Hello,
You are receiving this e-mail because you were listing a receiver on SDR.hu in the last 3 months.
I wanted to let you know that the SDR.hu project is discontinued.
This is because I have to focus on my PhD and unfortunately I don’t have enough time anymore to maintain the website and protect it from abuse.
If you have questions, there’s a FAQ on the front page: https://sdr.hu/
For KiwiSDR users there is another listing service available on the KiwiSDR website: http://kiwisdr.com/public (I’m not involved with this one.)
Thank you very much for having participated in the project!
VY 73!
Andras, HA7ILM
Alternative KiwiSDR Portals
Fortunately, there are a number of other KiwiSDR portals that do not require registration or a call sign. Here’s a list:
Yesterday, my family watched the successful launch of the NASA Demo-2 SpaceX Dragon via YouTube.
As astronauts Robert Behnken and Douglas Hurley communicated with Mission Control, we heard PTT confirmation beeps after each transmission.
Those beeps, of course, reminded me of past NASA missions and those iconic confirmation tones we heard in audio from the Mercury, Gemini, and Apollo days all the way into Space Shuttle missions.
I couldn’t find any information about Quindar Tones at the US Space and Rocket Center–although, admittedly, the place is massive and I could have easily overlooked it–so I did a little research when I returned home.
“I’ve always wondered what purpose the ‘beeps’ served that one heard intermittently during the voice communications with the Command and Lunar Modules during the Apollo missions, as well as other space missions.”
Journal Contributor Mike Dinn provides an MP3 clip ( 123k ) from a network audio check that includes numerous quindar tones.
Journal Contributor Markus Mehring replies:
“‘Other space missions’ is quite an accurate observation, since the ‘beeps’, in fact, are still in use today on Shuttle flights, at least on the UHF frequencies.”
“These beeps are called ‘Quindar-Tones’. Their purpose is to trigger the ground station transmitters when there is an outgoing transmission from Earth. The CapCom in the Mission Control Center, who is taking care of communications with the crew, uses his communication gear in a PTT mode exclusively. ‘PTT’ is short for Push-To-Talk, which means that the CapCom presses a button every time and as long as he wants to talk. (The crews back during Apollo – and also today – usually communicate via PTT as well, but they also have the so-called ‘VOX mode’ at their disposal, in which their microphones are voice-triggered by a certain adjustable threshold volume levels. VOX is used when they don’t necessarily have their hands free.)
When the CapCom presses his PTT button to start a transmission, an intro tone (2.525KHz sine wave with a length of 250ms) is generated and triggers the ground station transmitters to send. And when he is finished talking and releases the button again, a slightly lower outro tone (2.475KHz, sine, 250ms) is generated to trigger the ground station transmitters to turn off. So in short, these are remote control trigger tones.
Steve Schindler, an engineer with voice systems engineering at NASA’s Kennedy Space Center, offers the following history of [Quindar Tones] origins.
“Quindar tones, named after the manufacturer of the tone generation and detection equipment, are actually used to turn on and off, or “key,” the remote transmitters at the various tracking stations (Merritt Island Launch Area–now Kennedy Space Center, Bermuda, Australia, etc.) that were used to communicate with the Mercury through Apollo spacecraft and, in some cases, are still used with the Space Shuttle.”
[…]”Although it usually worked well, there were a couple of peculiarities with this system. If the transmitter was keyed and the telephone line connection broken, the transmitter would never get the tone to turn off. To prevent this there was a “transmitter on” light at each remote site that would come on when the transmitter was keyed. Someone was supposed to monitor the circuit and if the audio dropped, but the “transmitter on” light was still on, they would have to manually unkey the transmitter. Also, just before communications was handed over to a new tracking station, the key-unkey tone pair was sent 10 times to ensure that everything was functioning correctly. This was done before the audio was patched to the tracking station’s line so it wasn’t heard in the control room or on NASA Select audio.
The Quindar system was actually built from a piece of equipment that was used to put multiple teletype circuits on a single phone line by means of frequency domain multiplexing. Because replacement parts are no longer available, an “out-of-band signaling” system was installed in 1998 for the transmitters located in the U.S. This system uses a continuous tone that is below the normal audio frequency range. When the tone is present, the transmitters are keyed. When the tone is not present, the transmitters are unkeyed. It worked fine, but the Astronaut Office complained about the lack of tones which everyone had become accustomed to as an alert that a transmission was about to start. So, the Quindar tone generator, which was still installed in case it was necessary to key the transmitters at an overseas site, was re-enabled.
Even though you won’t hear the same Quindar tones in present-day space missions, you can listen until your heart is content at the website Apollo In Real Time.
If you’re fascinated with the NASA audio soundscape in general, you might check out the electronic music duo Quindar featuring longtime Wilco member Mikael Jorgensen, and art historian-curator James Merle Thomas.
Quindar: Mikael Jorgensen & James Merle Thomas. Photo by Chad Ress, Spacesuits by Cassandra C. Jones
Science Friday featured an extended interview with the group in 2017. If you love electronic music–especially if you’re a fan of Wilco, it’s well worth a listen:
Many thanks to SWLing Post contributor, Ferrie, who recommends the SigDigger digital signal analyzer written by Gonzalo Carracedo (EA1IYR). According to the project’s Github page:
