Digital Interference 40 meters

Discussion in 'Ham Radio Discussions' started by K0UO, Jul 14, 2021.

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  1. W7DGP

    W7DGP Premium Subscriber QRZ Page

    Well, the jamming has been S7 to S9 here in the Pacific NW. I have a rotatable dipole on 40 (SteppIR "trombone") and I can drop it an S unit by point an end to the SE. Not very directive. My waterfall matches those that have been posted except for signal strength. I agree that it is coming from Cuba where their govt and their people are in major disagreement. The Cuban govt dropped the Internet already and I think they ran out of things to do to block their citizens from each other and the outside world. So, they fired up their old jammer and pointed it to a section of 40M popular among Spanish speaking hams in the Caribbean. I noted that the jamming did not affect the FT-8 freqs nor the CW end. They're not targeting message flow because there isn't a message flow. However there may be some Cuban hams wanting to deliver health and welfare messages to stateside relatives. They can still do that on 40 CW - no jamming there that I can detect.
    Jamming a station vs a band of frequencies seems easier and probably was effective years ago when they jammed some Florida broadcast stations. This broadband jamming seems seems aimed at S Florida where the Cuban govt knows most of stateside relatives live. From my perch in the NW USA its just annoying. If I was a W4 in S FL I would be more than annoyed - "40 over 9"!

    One last observation. Watching the waterfall centered on 7135 or so, I noticed a QSO pip up freq, then watched it move down freq past 7135 then back up. Then a QSO popped up at 7140 and this moving pip coasted down and stopped on the QSO. Tuning in it was a W6 talking to a W2 station. The pip sitting on top of their QSO added a warbly sounding signal. Last night it was moving from 7110 to 7150 (or so) back and forth for quite a while. I'm wondering if that's a jamming signal that seeks an active transmitting station?
     
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  2. KP4SX

    KP4SX Premium Subscriber QRZ Page

    For one or two days early last week.
     
    KG4RRH likes this.
  3. N1FM

    N1FM Ham Member QRZ Page

    "Interestingly, as the Cold War escalated later into the ’50s and ’60s, some Americans actually began to see ham radio as a threat to national security, and ham enthusiasts as potential “sympathizers” to Communist programming coming out of Cuba, China, or the USSR. Fidel Castro’s regular speeches on Radio Havana raised enough concerns that Hallicrafters seems to have addressed the issue in an early 1960s advertisement, depicting an unnamed but obvious Castro at a microphone, with the extremely blunt tagline: “Have you ever actually heard this son of a bitch? You can . . . on a Hallicrafters Short wave receiver.”

    We’ve yet to confirm if this advertisement, pictured above, ever ran in any mainstream publications, or of it may have been more of an underground flyer, considering the language. Either way, the message seemed to be that Americans could rest easy knowing Hallicrafters didn’t like Commies after all."

    [​IMG]

    https://www.madeinchicagomuseum.com/single-post/hallicrafters/
     
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  4. KG4RRH

    KG4RRH Premium Subscriber QRZ Page


    Maybe the Chinese found a place to get rid of all those cheap, noisy, inverters and charge controllers ;);););).
     
    K0UO likes this.
  5. NN4RH

    NN4RH Premium Subscriber QRZ Page

    Gigantic grow light ?
     
    KG4RRH and (deleted member) like this.
  6. N1FM

    N1FM Ham Member QRZ Page

    There are 8 distinct noise sources on the voice portion of 40m from approx. 7105 to 7215 but I cannot verify it's coming from Cuba, based on the TDoA runs I performed. Today the TDoA map indicated a location just north of George Town on Grand Cayman. Last night, it was centered at Sugar Lake in Mexico -- Sugar Lake - El Azúcar (Presa Marte R. Gómez ) is located in the western part of Tamaulipas. The fix is dependent on the reference stations used to locate the source. Ideally, to provide a good fix, you would need a minimum of 3 receivers located N, S, and E or W of the source. Unfortunately the available SDR receivers don't provide an ideal geographical solution.

    See ARRL NEWS today

    FCC Investigating Alleged “Jamming” on 40 Meters
    07/22/2021


    "Reports suggest that jamming stations have been deployed on the lower portion of 40 meters. The jamming appears to be coming from Cuba. The signals, spaced at regular intervals, exhibit a squishy, popping noise. The apparent jamming showed up after anti-government protesters took to the streets in Cuba, followed by a government crackdown. So far, there’s no proven connection between the jamming and the protests, as evidence has been circumstantial. DX spots suggest that Cuban hams are on the air on SSB but do appear rare on 40 meters. A lot of Cuban spots point to FT8 activity. The jamming issue has drawn the attention of the FCC, which is looking into the matter, according to one tech publication."


    K4KKC has a good video recording with waterfall visuals of the interference.

     
    W5EBB, N0TZU and KM4OZ like this.
  7. KM4OZ

    KM4OZ XML Subscriber QRZ Page

    Thanks N1FM for a succinct unbiased report. I would point out that we all know the US has a distinct presence on Cuba at "Gitmo". While it does not seem likely they are causing the interference, they are certainly in a "position" to more closely investigate RF in the area. So any accurate useful and necessary information is likely to come from a collaboration with Military, State Dept. and FCC. I hope they share what they find but they may have reasons not to, also.
     
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  8. N1FM

    N1FM Ham Member QRZ Page

    Thanks. I can't say it's not Cuba, but based on the Kiwisdr data, I can't say it is Cuba. It would be great if we could tie a ribbon on it and say 'it's definitely Cuba, jamming it's citizens who are trying to communicate,' but I've never known the Kiwisdr TDoA to be that accurate with noise sources or SSB signals. It's great with big signals on the AM Broadcast band, like any 50,000 watt blowtorch, constant carrier, Clear Station broadcaster, but not so great with weaker ham signals on SSB, or diffuse noise sources. It clearly seems to be coming from somewhere between Northeast Mexico to somewhere near Cuba and Grand Cayman, but we'd really need a few USCG vessels or the equivalent to pinpoint the source of interference. If it were Cuba, why not simultaneously and continuously jam 75 meters, and 20 meters too, and why only part of 40 meters? I think there are more pieces to the puzzle that are yet to be examined.
     
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  9. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    I’m pretty sure that unusual radio signals in the Caribbean get US government attention, especially if interfering with marine channels, and (seemingly) connected with political instability or adversarial nations. Consider also the surveillance of the region for drug trafficking.
     
  10. K8XG

    K8XG XML Subscriber QRZ Page

    If you read the beginning of this thread, you will see there is a contractor with Government proprietary equipment access that pin pointed the Cuba and Venz as locations of jamming the 40meters Cuba, and 4/8mhz marine freqs. He could not provide screen shots due to the proprietary nature of the software/hardware. The Kiwi SDR videos came later.

    Also that it is has moved around and dropped a worm to certain hams talking in an open spot of then band.
     
    KG4RRH likes this.

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