North Korea intensifies shortwave jamming

FlagNorthKorea

(Source: DailyNK via Andrea Borgnino)

North Korea has been from the beginning of March continually signal jamming radio broadcasts on the shortwave frequency used by the South Korean non-profit broadcaster Unification Media Group (UMG). Given the present situation, in which North Korean residents might be influenced by outside information condemning the regime and explaining the purpose of the sanctions imposed by the United Nations, the regime has showed the will to block sources of outside information that might cause unrest.

The shortwave frequency […] in question, 7515 [kHz], has been actively jammed starting on March 1st making it extremely difficult for North Korean listeners to tune in. On the 15, UMG organization began using three receivers to test out reception at that and adjacent frequencies on a daily basis and was able to confirm that the exact signal is being jammed.

The blocking effort is being concentrated on the time period from 10pm- midnight. Specifically, from 10-11pm the jamming is very strong. The signal jamming is undetectable from midnight to 1am. The signal blocking became weaker at midnight on March 15, from which point onward the entire three hour broadcast was audible. Starting on the 17, UMG moved the frequency, but the jamming operators seemed not to notice because the interference continued on the old wavelength.

Continue reading at the DailyNK online…

Bad Signals: Transmitters in need of care

China Radio International via Radio Havana Cuba

Click to enlarge

Click to enlarge

Each morning, I enjoy listening to Radio Australia on 9,580 kHz, but I’m forced to tune elsewhere due to interference when China Radio International starts broadcasting on 9,570 kHz, via Radio Havana Cuba’s relay.

Hypothetically I should be able to mitigate any adjacent interference from CRI by listening to Radio Australia’s upper sideband. But unfortunately, RHC’s transmitters spew spurious emissions a full 20 kHz on either side of their carrier. It’s most annoying.

Here’s what RHC/CRI’s 9570 kHz signal sounds like on 9560 kHz:

Here’s what my waterfall looked like when CRI signed off:

CRI-Spectrum-2Notice how clear the 35 kHz waterfall window became (that’s Radio Australia centered on 9850 kHz):CRI-SignOff

The reason for this is clear: obviously, some of RHC’s transmitters are in need of care–and they’re not the only ones.

Radio Cairo

I’ve received a number of requests from Radio Cairo to post notices about their English language broadcasts. Normally, I’m quite happy to post press releases, but in each case I’ve mentioned that their English broadcasts are almost impossible to understand. For years, RC has had a problem with AM modulation (I assume) and, to my knowledge, have never addressed it.

I’ve sent RC feedback on a number of occasions; in response, I’ve received only the inconclusive reply that they’re “looking into the situation.”

To underscore the point, on Sunday Andrea Borgnino shared the following video/audio of Radio Cairo via Twitter.

There are other broadcasters that emit messy signals, but Radio Havana Cuba and Radio Cairo are the most noticeable in my listening area. And, it seems, neither broadcaster is in any hurry to address their ongoing problems.

In Radio Cairo’s case, especially, the broadcaster is simply wasting money by attempting to broadcast a signal that can neither be received nor interpreted. It’s rather sad. Ultimately, one has to wonder why they bother to broadcast at all…

Radio Havana Cuba, China Radio International,  and Radio Cairo (among others) take note: a little care of your radio transmitters will go a long way toward increasing your listenership. 

What you can do:  Consider contacting broadcasters when when you become aware of transmitter problems. Despite RC’s notable exception, oftentimes a broadcaster may not be fully aware of the issue––thus your feedback is necessary to help correct the problem.

US Signal Corps: Horseback mobile

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Source: Time Magazine; BETTMANN / CORBIS

Yesterday, I stumbled upon this 1940 photograph of the US Army Signal Corps communicating via radio in the field.

I bet that radio kit weighs almost as much as or more than the typical soldier!

Does anyone know what model of Signal Corps radio that would be?

Update…

Richard comments:

Thomas,

The original photo is at the site below.

At the link, https://tinyurl.com/hxp5akx

It’s a Radio Set SCR-203 (Phillip pack saddle mounted). Consisted of:
BC-228 transmitter – Transmitter, 2.1-3.1 MHz, 2 ea VT-25 & VT-50, Part of SCR-203
BC-227 receiver – Receiver, 2.1-3.1 MHz, Part of SCR-203
BC-235 control box – Control box, Part of SCR-203

The unit was powered by various battery packs and a GN-35 hand cranked generator and used a 25 ft whip antenna (Image: W.J. Schweitzer collection)

Thanks so much for identifying the equipment, Richard!

Paul seeks your input for upcoming broadcasts

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SWLing Post contributor, Paul Walker, is seeking your input for his next shortwave broadcast. Paul writes:

Thomas, I will be doing another shortwave broadcast in about 2 months and I need some input from your readers, particularly those in the US.

I will likely broadcast just on WRMI this time, but instead of an East Coast target area on 11580khz, I am going to aim for the Midwest & West Coast via 5850khz or 7570khz.

It appears the signals which are on 2300UTC to 1400UTC daily have the same beam at 315 degrees towards Vancouver, Canada. They both appear to cover the Midwest fairly well as hitting the west coast.

I would love to hear from readers if there is an actual difference in the two signals despite the same power and beam. Maybe one channel has adjacent channel interference or something.

If folks could check either frequency as close as possible to 0500UTC/12midnight eastern and note conditions on both signal and the differences between the two, I would appreciate it. (0500utc/12midnight eastern wlll likely be the time of my next broadcast.

One friend already reported slightly better audio processing and slightly better modulation. […]I want to know what my target audience in the Midwest & Western US thinks.

Thanks,
Paul

Please feel free to comment if you can assist Paul.

Kickstarter launch: The KiwiSDR for BeagleBone

Kiwi-SDR-1

Many thanks to SWLing Post reader and KiwiSDR developer, John Seamons (ZL/KF6VO), who notes:

The KiwiSDR for BeagleBone Kickstarter just launched:

https://www.kickstarter.com/projects/1575992013/kiwisdr-beaglebone-software-defined-radio-sdr-with

https://www.kickstarter.com/projects/1575992013/kiwisdr-beaglebone-software-defined-radio-sdr-with

Many thanks, John!

Those of you who had such a positive response to our previous post about John’s New Zealand-based web SDR, may consider supporting this Kickstarter and even installing a a KiwiSDR at your location! Check out the Kickstarter video for more information.

 

Paul Litwinovich on “The Life, Decline and Possible Rebirth of AM”

Zenith-Shuttle-DialMany thanks to the SWLing Post reader who noted this latest post by Paul Litwinovich at WSHU (Paul is frequently referenced here on the Post).

A short excerpt:

“AM occurs elsewhere in nature. A lightning strike or manmade electrical discharge will produce a burst of electrical noise that varies in amplitude. Since AM radios are designed to detect variations in amplitude, this is why they are prone to interference from such things. AM held sway as the primary method of modulating a radio wave up to WWII, not only for broadcasting, but for all types of radio communications.

Every vintage consumer radio, be it standard broadcast or shortwave, up to WWII, received amplitude modulated signals. Nowadays, AM broadcast stations are associated with lower quality audio, but such was not always the case. Receiver design really came of age in the 1930s with the superheterodyne circuit and advancements in loudspeaker design. The grand floor consoles of the late 1930s leading up to WWII were capable of producing audio that was very good, even by today’s standards, the only exception being that they were monaural, as stereo technology was still a ways off.”[…]

Litwinovich’s article is a must-read as he gives a concise overview of amplitude modulation, AM vs. FM, and even covers current proposed uses of the broadcast band (something we’ve also recently mentioned).

Click here to read The Life, Decline and Possible Rebirth of AM.

KIRO saves radio history by accident

Crosley-Dial-BlackAndWhiteMany thanks to SWLing Post reader, William Lee, who shared the following story from Mynorthwest.com about how radio station KIRO saved a bit of radio history through “accidental preservation.” Here’a an excerpt:

One of the most important events of the 20th century was World War II. The Cold War that followed and many of the national borders that exist to this day were largely created during that deadly, years-long conflict from the late 1930s to 1945.

An expert speaking at the Library of Congress at the first-ever Radio Preservation Task Force Conference described how one of the most important tools for understanding World War II is available to researchers only because of an “accident” at KIRO Radio more than 70 years ago.

During his keynote address last week in Washington, DC, longtime archivist and librarian Sam Brylawski spoke of KIRO Radio’s role in saving a priceless audio record of American history.

It was a case of “accidental preservation,” Brylawski told the audience of more than 200 radio history scholars from around the US and Canada, that resulted in the creation of a nearly complete archive of CBS news broadcasts during World War II.

“KIRO is the station in Seattle that cut lacquer discs to timeshift,” Byrlawski said, explaining how the scheduling of live broadcasts of CBS Radio’s news coverage was aimed at the Eastern time zone, which was not convenient for West Coast audiences. KIRO, as Brylawski described, violated network radio policies to make recordings of news programs on giant, 16-inch diameter discs, and then play them back a few hours later at times that were more convenient to Seattle-area listeners.

Continue reading the full article and listen to the audio report at Mynorthwest.com…