Category Archives: Digital Modes

Thank you, Carlos!

Carlos captures a number of Radiofax decodes with his XHDATA D-808

Many thanks to SWLing Post contributor, Carlos Latuff, who shares these recent Radiofax decodes on Twitter:

Hey Thomas my good man, have a look how good were the NOAA radiofax reception in Urca Beach, Rio de Janeiro, from USCG radio stations in Pt. Reyes, Boston and Honolulu:

Today, between 00h14 and 00h48 UTC, I received at Urca Beach, in Rio de Janeiro, #Brazil, radiofax from @NOAA broadcasted by @USCG in Honolulu, Hawaii, on the frequency of 16135 kHz USB. The only problem with this transmission is that the images were broken in some parts. pic.twitter.com/5geluA5eMv

— Carlos Latuff (@LatuffCartoons) December 5, 2023

Excellent propagation this afternoon at Praia da Urca, Rio de Janeiro, #Brazil, between 23h20 and 23h56 UTC, provided excellent reception of @NOAA radiofax transmitted from the @USCG radio station in Pt. Reyes, California, on the frequency of 22527 kHz. pic.twitter.com/w1zChefEmU

— Carlos Latuff (@LatuffCartoons) December 5, 2023

Gale warning issued today via radiofax by @NOAA for the Gulf of Tehuantepec, #Mexico.
Broadcasted by @USCG in Pt. Reyes, California, received at 22h14 UTC in Urca Beach, Rio de Janeiro, #Brazil, frequency of 22527 kHz USB. pic.twitter.com/ISmnMcMwM0

— Carlos Latuff (@LatuffCartoons) December 5, 2023

Excellent propagation this afternoon at Urca Beach, Rio de Janeiro, #Brazil, between 21h15 and 22h02 UTC, provided excellent reception of @NOAA radiofaz broadcasted from the @USCG radio station in Boston, on the frequency of 12750 kHz USB. pic.twitter.com/m5o54U1tod

— Carlos Latuff (@LatuffCartoons) December 5, 2023

Patrizio seeks information about mystery signals he’s discovering across the HF bands

30 Replies

Many thanks to SWLing Post contributor, Patrizio Cardelli, who has discovered some interesting signals on the HF bands and is seeking information about them.

A little background: Patrizio asked me about these signals a few weeks ago and based on a quick glance at the spectrum and waterfall images I assumed it was DRM (Digital Radio Mondiale). I was wrong, of course. Had I looked at the actual frequency and bandwidth, I would have immediately realized is was not DRM. My email load has been so heavy as of late, and my time to reply at such a premium, I rushed through the reply–my apologies, Patrizio!

Patrizio followed up with this message:

Hello Thomas,

I hope this message finds you well. I wanted to share my recent radio exploration based on your advice. I followed your suggestion and investigated a sample signal within the 60-meter band, specifically settling on the one at 4.962 kHz.

I attempted to decode it using the Dream software but encountered no success. It seems this isn’t a Digital Radio Mondiale (DRM) transmission. To rule out local QRM (interference), I tested various Kiwi SDR receivers across Europe, both to the south and north of my QTH. Interestingly, I managed to pick up this signal everywhere, with a stronger intensity noted in the northern locations.

I’m eager to publish this article to find out if other Shortwave Listeners (SWL) have been able to decode this transmission. Additionally, I’d like to mention that similar signals, either continuous or intermittent, are present on various HF frequencies.

I look forward to any insights or experiences others in the community might have regarding this intriguing signal.

Audio sample:

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While I recognize these signals now, and I’m sure most of you who cruise the bands have seen/heard these as well, Patrizio is a relatively new SWL, turns out, and I thought it might be fun exploring just what these signals are.

Readers: If you know what these signals are, please comment. Indeed, I’m sure there are a number of SWLing Post readers who have hands-on time with generating these signals as well in a past life or current career. Let’s explore!

John improves his Radiofax game!

5 Replies

Earlier this week we posted a note from John who only recently took a deep dive into the world of Radiofax transmissions, inspired by Carlos Latuff‘s recent posts.

I mentioned to John that he’ll hone his skills the more he captures these Radiofax transmissions. John just sent the following update:

Thanks, Thomas!

Indeed you are correct.

Having more luck decoding the Boston service… remembered I have a Sony AN-LP1 external antenna and so I unpacked and unraveled it and plugged in to the D-808 … drop that noise floor and…

12179kc USB Fine Tune +50

Above is the best example I have so far with HF FAX.

I guess it’s rather easy to decode these overall once you get the noise floor down, and fine tune the signal. These transmissions can take several minutes to complete which allows for a great deal of fade during that time.

Here is the original version [via the OPC Mobile Website – Atlantic]:

Radio has filled my off-hours for the best part of 50 years now. I should no longer be surprised to find something I had overlooked like this that just adds to the fun and challenge of it.

72s and 3s.

John Johnson
N8ELK

Thank you so much, John, for sharing this with us! That is a brilliant decode, indeed!

QSL: Australian Radiofax Received in Brazil

2 Replies

Many thanks to SWLing Post contributor, Carlos Latuff, who writes:

For the first time, I received in Porto Alegre a noisy radiofax from the Bureau of Meteorology of Australia: Mean Sea Level Pressure (MSLP) map.

Frequency of 20469 kHz USB, 08h45 UTC.

Radiofax (noisy)

Original

My request for a QSL card was kindly answered (attached along the radiofax and the original chart from BoM’s website). Notice that BoM’s transmitter is 1 KW only!

I realize that your Radiofax decode wa noisy, but I feel like that’s an impressive feat considering the distance involved, the fact that your radio was a portable, and their output power was only 1,000 watts. Proper Radiofax DX! Thanks for sharing!