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Author Topic: Data transmission 4.997 to 5.005 MHz  (Read 2208 times)

Offline Mixer

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Data transmission 4.997 to 5.005 MHz
« on: April 02, 2020, 0420 UTC »
Noted on the WOR mailing list by several individuals UTC 2 April 2020 since at least 0110 UTC. A data signal of some kind, about 6 KHz wide, causing a lot of interference to WWV on 5.000 MHz.

Lower edge about 4.997 MHz and upper edge about 5.005 MHz.

It was quite strong at my QTH in upstate NY when checking at 0210 UTC, but is weaker now. Being heard on multiple Kiwi SDRs, with midwestern and eastern receivers getting much stronger signals than in the western US. I could even here it weakly on the U Twente Web SDR   in the Netherlands.

Preliminary TDOA analysis seems to be pinpointing a ďhot zoneĒ on an axis from northern Indiana up towards Chicago, and indeed signal levels on individual Kiwis near Indianapolis and Chicago appear to be quite strong.
Location: Upstate New York (Southern Tier) Grid FN12
SDRs: RSP1A, ANAN 10E, Airspy R2, Airspy HF+
Analog Receiver: Drake R8B
Antennas: 80 meter dipole, Wellbrook AL1530LN Loop

Offline Token

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #1 on: April 02, 2020, 1319 UTC »
I did not get a chance to look at this signal closely, however, at first glance it was 850 Hz shift FSK.  It appeared to have only two tones of actual data, however 5 or 6 tones were seen, making it very wide.  Each of the tones appeared to be a duplicate of one or the other of the two tones with unique data.

Total guess here, but it looked like a distorted STANAG 4481 FSK signal.  I would guess a spur or broken transmitter.

Unfortunately, I did not make any recordings of the signal, literally every receiver and PC here at the desk was tied up making other recordings at the time.

T!
T!
Mojave Desert, California USA

Offline Mixer

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #2 on: April 02, 2020, 1429 UTC »
Still ongoing at 1425 UTC 02 APR. Weak but noticeable here in NY state, with WWV also being heard. Itís still quite strong on Kiwis in the midwest, but I canít hear it at the moment on your Kiwi in California.
Location: Upstate New York (Southern Tier) Grid FN12
SDRs: RSP1A, ANAN 10E, Airspy R2, Airspy HF+
Analog Receiver: Drake R8B
Antennas: 80 meter dipole, Wellbrook AL1530LN Loop

Offline ChrisSmolinski

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #3 on: April 02, 2020, 1714 UTC »
Audible here in MD at 1714 UTC.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
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Offline Traveling Wave

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #4 on: April 02, 2020, 1806 UTC »
1800 UTC - Steady S7 signal in WNY. Five to six tones are present.
Location: Western New York ( Niagara Frontier)
Radio :TS480 with RTL-SDR pan-adapter, HDSDR software, Omni-Rig Control, Zenith T/O R600,T600
Antenna: 40m dipole, 20-17-15 meter fan dipole. One of N. Tesla's own prototypes. A high-powered mutant of some kind never even considered for mass production.
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Offline Strange Beacons

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #5 on: April 02, 2020, 1847 UTC »
The signal was still present at 1830 UTC, same spread of 4997 to 5005 kHz. I tuned in very strong signals via KiwiSDRs located around the Northeast, with only a very weak signal in other areas of North America.

Offline JCMaxwell

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #6 on: April 02, 2020, 2148 UTC »
Still S9 here in NC
IC-R9000L, FDM-S2, Belka DX, HF+ Discovery, RSPdx, IC-R30, BC125AT, PL-880 <- W6LVP Loop

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Offline Josh

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #7 on: April 02, 2020, 2239 UTC »
Bet it's 4985 Davidsonville, MD S4481 fsk with spurs.
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Offline videogame57

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #8 on: April 03, 2020, 0010 UTC »
I have it here in Toronto, pretty strong, been going all day. Here's a snippet of waterfall.

Here's a short recording in original PCM, and a 90 minute recording encoded to Vorbis to save space.
https://cdn.discordapp.com/attachments/400099900840214529/695380332324585572/17-06-16_Unknown_4997.62_kHz.wav
https://cdn.discordapp.com/attachments/675850914732572697/695424474706739200/17-14-23_Unknown_4997.14_kHz.ogg

Offline Mixer

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #9 on: April 03, 2020, 0519 UTC »
At 0515 on 3 APR, there now appears to be just a standard 850 Hz FSK transmission, with the lower frequency at about 5001.6 and the upper at 5002.4
Location: Upstate New York (Southern Tier) Grid FN12
SDRs: RSP1A, ANAN 10E, Airspy R2, Airspy HF+
Analog Receiver: Drake R8B
Antennas: 80 meter dipole, Wellbrook AL1530LN Loop

Offline Mixer

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #10 on: April 03, 2020, 0609 UTC »
Bet it's 4985 Davidsonville, MD S4481 fsk with spurs.

I just ran the TDOA algorithm twice in a row using Kiwis in Virginia, Pennsylvania, Maryland and Ohio on 4985, and it did pinpoint it pretty close to its actual location (the center of the bullseye was about 75 miles southwest of Davidsonville). I then immediately ran the TDOA twice on the mystery signal using the same 4 Kiwis, and it showed a completely different result - multiple spokes with no clear source - indicating probable 1 or 2 hop propagation from a different location.

Iíll try it again later today during daytime if itís still on.

Right now, the transmission is back to standard FSK, about 1.5 KHz above WWV.
Location: Upstate New York (Southern Tier) Grid FN12
SDRs: RSP1A, ANAN 10E, Airspy R2, Airspy HF+
Analog Receiver: Drake R8B
Antennas: 80 meter dipole, Wellbrook AL1530LN Loop

Offline Token

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Re: Data transmission 4.997 to 5.005 MHz
« Reply #11 on: April 04, 2020, 0102 UTC »
Bet it's 4985 Davidsonville, MD S4481 fsk with spurs.

Unfortunately it probably is not, I compared the two signals and the 5000 USB signal was unique data to any S4481 FSK I could find for comparison.  I checked them all from 2000 kHz to 14000 kHz (propagation left nothing above that for me to check).

I agree, it looks like S4481 FSK, and my first thought was spurs, but I could not find a matching transmission anyplace.

T!
T!
Mojave Desert, California USA

 


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