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Thread: Not being able to use equipment due to some type of signal jamming

  1. #1
    coopcity6 No Longer Registered

    Exclamation Not being able to use equipment due to some type of signal jamming

    I live in NYC, and for some time now, i would have to say for about the 5 months, my radio communications have dwindled due to a blockage of some type.
    I run all commercial gear, and i am antenna restricted, but this has not stopped me from getting into some of the larger repeater systems in the area. KQ2H for example is one of them.
    At times i have to run my uhf maratrac at rated power T81 model to get in full quieting. Compared to my maxtrac which i was able to use and be fine.
    I have noticed on a certain repeater system on 447.625, i can key the repeater ( on my portable) and as the repeaters hang time is going, you can hear a very distinct chirp of some kind.
    If i can post a audio clip i would do it, if someone tells me how to do it.
    Now behind me is the secret service, and xm satelitte service, and other federal agencies that are down in the lower 400's.
    NYPD has their transmitter up there but they dont bleed anywhere.
    you may be thinking well it may be your radio, but i can use my maxtrac at times when whatever it is not transmitting.
    Anybody have this experience, and what did you do to rectify the problem, other then obvious moving?


  2. #2
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    I don't think XM would have anything to do with your problem. SDARS operates within the S band of 2.3 GHz, even the terrestrial repeaters operate in this spectrum.

    Without hearing the interference, it is going to be hard to help you.

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    You definitely have a strange problem. It sounds like there may be something near you that is mixing with your signal or overpowering it somehow making you need extra power to get into local repeaters, is that right?

    Generally when you have problems like this, try to characterize the interference. Is it always at the same time of day? Does it come and go with any pattern? Is the problem present on just one frequency or across the band? Is the problem present on more than one band? There are lots of characteristics that may help you to categorize or narrow down the possible sources of interference.

    Maybe you're living next to the "Acme Spark Gap Generator Co." or something that might give you a clue if it starts at 8:30 and ends at 3:30 it may be a factory nearby causing the problem. Maybe it's a neighbor running a noisy fluorescent lamp. There are endless possibilities so you have to try to narrow it down. A spectrum analyzer would also be of invaluable assistance, giving you the ability to compare background noise levels, etc. when it's happening vs. when it's not. Maybe someone in a local Ham club has one they can help with, hams frequently love to do "Foxhunts" like that. Finding interference can be fun like looking for a hidden transmitter. And I can pretty much guarantee you'll be surprised and amused to find out what the source of the interference is!

  4. #4
    coopcity6 No Longer Registered

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    Well, its a high rise residential area. There are a total of about 35 buildings that either 24 floors or 32 floors high spread over an area of about 3.5 miles.
    The noise that I hear for sure on 1 frequency but I am unable to use equipment on ANY band .
    Most eefected is hf and uhf. Vhf seems to have a little more lee way of being able to get out.
    Its like the house is a RF hole, black hole of radios.
    There are no factories near by, shopping is available but stores and food no manufacturing, the only thing that may do it is, there is a place that makes electricity using a jet engine.
    But I work on planes and that would nit cause a malfunction of radios.
    I can try to post a file of the noise I hear.

  5. #5
    PRC148 No Longer Registered

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    Quote Originally Posted by coopcity6 View Post
    there is a place that makes electricity using a jet engine.
    WTF are you Mad Max from the future or something?

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    Those are extra-demand power stations. They supplement the regular coal and nuclear power stations during peak periods, and they are a bunch of stationary jet engines shaft-driving alternators. They kick in usually at peak load times i.e. afternoon to early evening, more so during summer months of course... They only use them when the normal plants can't keep up with the demand, because they are very expensive to operate.

  7. #7
    W2WP No Longer Registered

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    Sound like RF from a local source. Take a HT and start going away from your home. Does it go away?

    It's not the KQ2H repeater. I live in Bayonne and have no issues. I know 10 meters has been open but that's not it.

    Mark / W2WP

  8. #8
    coopcity6 No Longer Registered

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    What's up mark we know each other and no its not Alex's machine its something in the bldg.
    I called cable vision and they came on Sunday for a service call and I told them there was a rf leak in the bldg. So hopefully they find it but with the ht I can follow the noise for a limited area before it drops but louder towards the ceilings and less towards the floors

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    The right answer is a spectrum analyzer. Get an idea of what the noise floor is in a similar environment, but where your radios work properly. Then, check your home. You could be looking for anything - a failing switch-mode power supply, a glass-break detector, a TV antenna amplifier, a cell phone amp, who knows. I've been known to stick a small rubber duck on the end of a piece of RG58, connect that to my NetTek spectrum analyzer module, and use it as a sort of "contact probe". When you find the culprit, it will be very obvious on screen.

  10. #10
    W2WP No Longer Registered

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    Quote Originally Posted by coopcity6 View Post
    What's up mark we know each other and no its not Alex's machine its something in the bldg.
    I called cable vision and they came on Sunday for a service call and I told them there was a rf leak in the bldg. So hopefully they find it but with the ht I can follow the noise for a limited area before it drops but louder towards the ceilings and less towards the floors
    Any luck with Cablevision?

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    Maybe even try using one of the Realtek SDR dongles with HDsdr or SDR#... it's a cheap way to get a nice graphical representation of whats going on around you.

  12. #12
    standardmissile No Longer Registered

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    Coopcity6, PM me where in NYC you live, I have an inkling about what may be causing your RF interference if Cablevision doesn't find a signal leak.

  13. #13
    coopcity6 No Longer Registered

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    here is an update to my situation.
    I borrowed a frequency counter and i did a sweep of my hallway and the floor that i live on.
    So as i do the sweep, i get a pretty steady reading between 160 and 180 mhz.
    Here's the kicker: the moment i step foot in my door, at the threshold of the apartment i get a jump on the frequency.
    what kind of jump? from 180 to 245 mhz. thats a big jump.
    No matter where i go in the house, the counter bounces around up there, leave the house into the hall and then boom back down 40 megs.
    Any ideas???

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    Those frequencies would be typical for cable TV/broadband type interference. I used to have an old Radio Shack multiband radio that had open tuning of VHF from 118 or so through 230 MHz or so. I think it was called the "Patrolman 9" or somesuch. Something like that would be perfect to sweep around and see if you are getting regular burps of stuff every few MHz or so (indicating a channelized signal structure).

    Since you're pretty sure it's coming from your apt, try turning off your master breaker briefly and see if it goes away. It'll suck having to reset all your VCR's and clocks, but it will be worth it to see if it's one of your appliances or gadgets. If it doesn't go away it might be cable leakage or coming from a neighboring apt.

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    Are there any LED light bulbs installed anywhere near your apartment? I put some in my home and the noise that these damn things produce is nothing short of amazing.
    Quote Originally Posted by Bigfella237 View Post
    I've never really bothered 'playing' with ADP (it's like owning a Harley but still riding a tricycle)