Many thanks to SWLing Post contributor, John, who shares a link to this recent tour of WRMI, by Ham Radio Concepts:
Video tour of WRMI
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Author Archives: Thomas
Carl Laufer of RTL-SDR.com on HamRadioNow
(Source: Southgate ARC)
Carl Laufer’s RTL-SDR on HamRadioNow
Carl Laufer isn’t a ham (yet), but he got caught up in the RTL-SDR craze in his home town, Auckland NZ, as he was completing his PHD
He began writing about them, and selling them, on his blog at www.RTL-SDR.com, and soon discovered that the little SDR receiver dongles could stand some improvement.
So he designed ways to make them work better, and contracted a Chinese manufacturer to build them with his mods. That just about doubled the price, from $10 to about $20. Yeah, big deal.
TAPR invited Carl to come to the 2017 Dayton Hamvention to talk about them at both their Friday Forum (part of HamRadioNow Episode 324) and as the main speaker at the TAPR/AMSAT Banquet.
And we got him for a conversation with HamRadioNow’s KN4AQ and PhasingLine’s Chicken With Fries in the SIB back in Tent City.
Watch HRN 328: Carl Laufer’s RTL-SDR on HamRadioNow:
Click here to watch on YouTube.
I got to meet Carl at the Hamvention this year–what a great guy and his website is certainly the best source of information about the RTL-SDR.
I should note that I also met with contributor, Mike Ladd, in person at the Hamvention. Mike now works for SDRplay.
This is one of the great things about gatherings like the Hamvention–it brings together so many people that you’d otherwise likely never meet in person!
NASA’s ionospheric experiment tonight and remembering The Woodpecker Project
The gas mixtures from NASA’s ionospheric experiment cause parts of the night sky to glow blue and green. (Photo: NASA)
Many thanks to SWLing Post contributor, Ed, who writes:
It might be interesting if you invited SWLing Post readers today see how NASA’s ionospheric experiment tonight (shortly after 9:00PM ET) affects RF propagation along the east coast:
I searched online to find any reference to this long series of NASA experiments affecting RF propagation, and found this 1980 paper:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810005401.pdf
…which contains this paragraph:
Ionospheric Modifications
The objectives motivating various experiments based on either decreasing or increasing the ambient plasma density by means of a chemical release include: (a) obtaining measurements of the rate of refilling after creation of a plasma depletion “hole” as a means of studying ambient ionization processes, (b) studying the magnetic field aligned propagation of VLF waves by creating a propagation duct, (c) simulating the formation and movement of the natural depletion “bubbles” which occur over the magnetic equator, (d) investigations of reaction rates, recombination coefficients, airglow production, etc., and (e) creating the conditions for inducing selected plasma instabilities to produce ionospheric irregularities and spread-F conditions. The science objectives in these experiments have a direct bearing on communication problems. Other forms of ionospheric modification are directed toward studying ionospheric/magnetospheric coupling and testing plasma theories.
So it might be fun to crowdsource from the SWL community to see if we can detect any propagation anomalies Tuesday night during this brief experiment. It’s unfortunate there’s not more time to coordinate different listeners monitoring different assigned frequencies. This reminds me of participating in ANARC’s “Woodpecker Project” in 1985 with 95 other SWL’s in 18 countries to determine the interference effects on HF broadcast from the Soviet Union’s use of Over-The-Horizon (OTH) radar in the HF bands.
I wonder how many SWL’ing Post readers participated in The Woodpecker Project and still have the nice “No Woodpeckers” tee shirt they earned for submitting their findings, which were combined into a final report that condemned the Soviets for causing interference on the HF bands.
Thanks for the tip, Ed! According to the linked article, the experiment will take place this evening, “soon after nine o’clock eastern time” (or 01:00 UTC).
This would be a great time to do an SDR wideband spectrum recording since you could possibly see any propagation effects on the waterfall display and play the event over multiple times. I’ve no clue if this experiment would yield any discernable results on HF, but it would be fun trying to detect it nonetheless.
Please comment if you plan to check out the experiment and/or if you were a participant in the Woodpecker Project!
2017 Hamvention photos: Saturday Flea Market
While looking through photos I had backed up on my laptop, I discovered a set I took at the Hamvention Flea Market on Saturday morning (May 20, 2017). I’ve gotten tremendous positive feedback from the photos I posted of Hamvention Setup, the Friday Flea Market and Inside Exhibits, so I thought I’d post these as well.
Below, you’ll find 84 additional flea market photos. Click on the thumbnail to expand each photo. I’ve tried to include price tags when possible. I’m sure some of these items are also featured in my Friday flea market photo album. Enjoy:
Radio Erena “provides a voice for the voiceless”
(Source: Open Democracy)
Eritrean radio station Radio Erena provides a voice for the voiceless
Broadcasting from Paris, Fathi Osman’s Radio Erena challenges the government’s monopoly on truth and champions those who gave their lives for freedom of expression.
Last night turned out to mark a double-celebration for Eritrean journalist Fathi Osman. While the father-of-four nearly let his 51st birthday slip by unnoticed, he certainly couldn’t play down his radio station’s spectacular win at One World Media Awards in London’s BAFTA building.
Radio Erena (‘Our Eritrea’) broadcasts from Paris, where Fathi now lives with his wife and children, having fled the dictatorship five years ago. The station was founded in 2009 by the well-known exiled Eritrean journalist Biniam Simon, with support from Reporters Without Borders. The goal? To offer a lifeline of independent news, information and entertainment for Eritreans both in their homeland and worldwide.
As Fathi held out his hand to shake mine, he noticed his fingers were stained inky blue. “Ah, you can tell I’m a writer,” he observed with a smile. Currently Radio Erena’s Assistant Project Manager, in the past Fathi worked variously as a journalist and diplomat before he left the Eritrean embassy in Riyadh to seek safety in France. “I had developed ideas that the government did not accept,” he explained, “and you know, with these kinds of conflicts, in the end you will meet trouble.”
Fathi’s family was among more than 4,000 Eritreans who flee each month. And is it any wonder, given the UN June 2016 report that the regime has been responsible for crimes against humanity since 1991? Known globally as a predator of press freedom, President Isaias Afewerki has led Eritrea to be ranked consistently as the very lowest of 180 countries in Reporters Without Borders’ World Press Freedom Index, though in 2017 the regime came second-last as North Korea deteriorated even further.
Afewerki’s purges in September 2001 ended Eritrea’s free press – by now, seven of the 11 journalists arrested at that point have died in detention. This year at least 15 journalists are believed to be detained without charge or trial. Dawit Isaak, a Swedish-Eritrean citizen who had returned to Eritrea to open Setit – the first independent newspaper there, has not once talked to a lawyer in 16 years of imprisonment. His fate is unclear.
Far from having deterred the four journalists based in Radio Erena’s newsroom (as well as their 25 or so correspondents worldwide), these appalling abuses have driven them to pour every effort into remedying the crackdown. The station broadcasts in Tigrinya and Arabic by satellite and short wave – and is available online or via a mobile phone app.
“Within the whole of Eritrea there’s only one radio station, one newspaper,” Fathi explained. “That means the ‘truth’ is dominated by the government. Radio Erena is working to counter that. We do everything, from exposing news that the government doesn’t want people to know, to hosting shows for singers and writers – and raising awareness of human rights is very important to us.”[…]
Continue reading the full article on Open Democracy’s website.
Note: Radio Erena can be heard on 11,965 kHz between 1700-1800 UTC. They broadcast from Kostinbrod in Sofia, Bulgaria with 50 KW.
KiwiSDR network updates include native HF FAX
Many thanks to SWLing Post contributor, Mark Fahey, who writes:
Lots happening with KiwiSDR – there are now over 130 live 0-30MHz fully controllable SDRs scatted around the world some in really interesting locations. Using Kiwi’s around the world is like being able to go on a exotic DXpedition any time.
Here (attached graphic) is a map of the current locations, you can see the live status of online receivers here:
and as a list of receivers here:
KiwiSDRs now include HF Fax reception natively, just select Fax in the Extension menu, select the part of the world you are interested in and the Kiwi will tune the weather fax frequency and receive the weather fax all natively (no extra software needed) – too easy!
Lots more great things happening.
Here is the latest news…
http://www.kiwisdr.com/#id-31-may-17
Cheers,
Mark
Thank you for the update, Mark! I had no idea the KiwiSDR app had an HF Fax extension. After reading your message, I loaded a KiwiSDR session in Europe and used the Fax feature. It couldn’t have been easier. The screen grab (above) came from my first attempt.
The KiwiSDR network is truly amazing. I use it all the time–especially if there’s an important broadcast happening and I can’t easily receive it at home or while traveling. As an example, during the recent French elections, I listened to results roll in on France Inter mediumwave from a KiwiSDR in Italy. It felt like being there.
My one feature request would be that the KiwiSDR app include some form of native broadcast recording like the WebSDR at U Twente.
Many thanks for the update, Mark!
Click here to read about Mark’s KiwiSDR installation.
Would you like to host your own KiwiSDR?
The whole system only costs $299 US. The KiwiSDR site has a list of distributors around the world.
Amazon has units in stock at $299 US shipped.
I would have purchased a KiwiSDR ages ago–during their Kickstarter campaign–if I only had the Internet bandwidth at home to support it. My Internet speeds are likely lower than anyone else here in the SWLing Post community. One of the compromises living in a relatively remote spot with no RFI. 🙂
How to build a Milk Crate AM Broadcast Loop Antenna
Many thanks to SWLing Post contributor, James Townley, who shares the following guest post originally posted on his Shortwave/Medium Wave blog:
540 kHz to 1700 kHz Loop Antenna (Click to enlarge)
AM Broadcast Loop Antenna
by James Townley
Several years ago, I became interested in medium wave DXing. One of my limitations was the size of my yard, so I developed an interest in tuned loop antennas to compensate, because setting up a beverage antenna was out of the question. I experimented with different sizes of loops, and found that the bigger the aperture, the more gain the loop would have. The tuned loop antenna is also very directional, which allows you to reject, or null out interference from either noise or other stations. Loops are considered bi-directional in that they receive to the front and back, but not to the sides. The tuned loop antenna quickly became my weapon of choice for medium wave DXing.
Recently when the weather began allowing me to enjoy the outdoors, I decided to make another smaller loop antenna from a plastic milk crate I had lying around. I saw the idea on the internet when I observed that someone had used a milk crate for their loop. Click here to see a variety of tuned loop antennas that others have made. Whichever material you decide to make your loop antenna from, just make sure that it is not a conductive material. Wood, plastic, and cardboard seem to be popular materials for loop making. In the photo above, I am using my Sony ICF-2010 to listen to WCCO on 830 kHz. This station is nearly 200 miles south of me, but I am able to receive it with 9 LEDs lit on my signal strength meter while using the loop. There is no direct connection of the loop to the radio, it is inductively coupling with the radio’s own ferrite rod antenna.
If you are interested in making a loop antenna like mine, here are the materials you will need:
120 ft of 18ga insulated wire (I bought a 100 ft spool of cheap speaker wire and pulled the 2 conductors apart):
1 – Plastic milk crate
1 – 15 to 365 pF air variable capacitor (found in many old radios, or a google search to buy one from an internet store)
1 – Tuning knob. Any knob will do as long as it fits the shaft on the variable capacitor.
1 – Tape or wire ties. I used tape to secure the wire while winding, then hot glue when finished.
When you begin to wind your coil, use tape or a wire tie to secure the wire, and leave about a foot of wire. This extra foot of wire will later be soldered to the frame on the capacitor. As you wind your coil, pull the wire snugly and with each turn leave about a quarter inch spacing between each turn. The spacing isn’t critical as long as the spacing is consistent. I wound 21 turns on my crate. This may differ for you, depending on the size of your crate, or the value of you capacitor. If you find that the bottom frequency isn’t low enough, you can add more wire to make a few more turns. This will lower the bottom frequency for you.
After winding the coil, you can solder each end of the coil to your capacitor. The beginning of the loop gets soldered to the frame of the capacitor, and the other end of the coil to the rotor solder lug on the side of the capacitor. If you do not have a soldering iron, you can use alligator clips to connect your loop coil to the capacitor as well. I secured my capacitor to the inside corner of the crate with hot glue. I put a generous amount of the hot glue onto the bottom of the capacitor frame, and held it to the crate until the glue cooled enough for the capacitor to stay on it’s own. I used enough to get the job done, but not so much that it interfered with the plates in my capacitor. The hot glue seemed to adhere very well. I then checked the spacing of my coil turns, and secured them with the hot glue as well.
I was very impressed with the results after spending some time with the loop. It’s small enough to maneuver around easily, but big enough to give it some gain, so I can listen to daytime DX. I may make another tuned loop using two crates to see how much more gain I get with the larger aperture.
Happy DXing,
James Townley
Many thanks, James, for sharing your project with us! This loop appears to be relatively simple and accessible even to those with little knowledge of soldering or homebrewing. I’m now wondering how a loop made of four milk crates might perform!