Thanks Thanks:  0
Likes Likes:  0
Results 1 to 14 of 14

Thread: External RF noise

  1. #1

    Join Date
    Sep 2003
    Posts
    6,628
    Post Thanks / Like

    External RF noise

    In the 1960s all one had to do was report an emitter, and BAM - fixed.

    Not so much today - there are several emitters around our major airport that just overwhelm some of the better com radios. I report them and the authorities shrug. I even got the phone number of the local FAA office that deals with com and nav issues, and the reaction there was "who gave you this number?"

    Granted, the radios most affected seem to be Garmins, including the 300, SL-40, and especially the GTR-200 which is a spectacular radio and would be better with a wider range RF squelch circuit, but these emitters are getting more and more powerful.

    We have one pinpointed - it is either a VW dealer or a Mercedes dealer (or both) right off the end of 28 right, and it is deafening! Really loud!

    Anybody know of an effective way to get these things fixed?

  2. #2
    BC12D-4-85's Avatar
    Join Date
    Feb 2016
    Location
    Fairbanks, AK.
    Posts
    1,498
    Post Thanks / Like
    You could drive around with your handheld aircraft band receiver and source the harmful interference. It appears you may have done that. Walk up to the source and have a word with the owner. The FAA/FCC would need that location and source info prior to you contacting them. It's probably what they would call an "unintentional or incidental radiator" signal coming from an electronic device like signs, security devices, or lighting. There's more.

    The long and often bumpy road might then start with the Federal Aviation Administration Spectrum Management offices:

    https://www.faa.gov/about/office_org...ec_management/
    https://www.faa.gov/about/office_org...tions/fmos.cfm

    The problem you're experiencing is common and growing as manufacturers of power supplies and devices often fail to comply with FCC Part 15 requirements:

    https://www.ecfr.gov/cgi-bin/text-id....1.15&rgn=div5

    Gary

  3. #3
    wireweinie's Avatar
    Join Date
    Aug 2013
    Location
    Palmer, AK
    Posts
    2,398
    Post Thanks / Like
    FCC is the governing body for anything that transmits a signal.

    How did you pinpoint the source?

    Web
    Life's tough . . . wear a cup.

  4. #4
    BC12D-4-85's Avatar
    Join Date
    Feb 2016
    Location
    Fairbanks, AK.
    Posts
    1,498
    Post Thanks / Like
    The critical issue here is potential interference with coms used to manage aircraft flow and ensure safety within the National Airspace System. As noted above if the interference overwhelms the aircraft's ability to maintain a required 2-way communication then I believe both the FAA, FCC, and potentially the FBI may be interested.

    However finding and going to the source can be easier and quicker in my experience.

    Gary

  5. #5
    slowmover's Avatar
    Join Date
    Nov 2003
    Location
    Little Rock, AR
    Posts
    326
    Post Thanks / Like
    Back in the day when I was flying C-130s during the Iraq war, comm was very difficult around the major bases because the Army put jammers on their vehicles to disrupt radio-detonated IEDs. I imagine their technique worked to defeat IEDs, but it also made ATC comms within a couple miles of the airfield suuuuuper hard. It never got fixed as long as I was in Iraq.

    But as the story goes, an Army general happened to be on the flight deck of one of these Air Force C-130s one day and figured out what was going on. He put a stop to it, quick. Later, in Afghanistan, I sometimes saw "jammer off" signs around airfields to remind Army vehicle drivers to flip that switch or whatever.

    So, I sympathize with your problem! And I hope going to the source will fix the problem. It would be a shame if there was an accident or fatality due to preventable communication interference.

  6. #6
    BC12D-4-85's Avatar
    Join Date
    Feb 2016
    Location
    Fairbanks, AK.
    Posts
    1,498
    Post Thanks / Like
    Have a qualified radio technician confirm and maybe adjust the squelch consistent with normal operation at typical noise levels.

    For the SL-40 see Configuration Mode for alternative squelch threshold adjustments: https://fccid.io/EOJCOMM25-10/User-M...-Manual-422526

    For GTR-200 see for same: http://static.garmin.com/pumac/190-01553-00_H.pdf

    Gary

  7. #7
    wireweinie's Avatar
    Join Date
    Aug 2013
    Location
    Palmer, AK
    Posts
    2,398
    Post Thanks / Like
    Do other pilots report the same issues? How about other radios? Do they have the same problems? What about when you fly into other metro fields? Compare your issues to someone with something like a KY 97A or Becker AR6201.

    This may be interfering with aircraft radios, but as stated above , the FCC will be the final authority if it comes to a peeing match.

    Web
    Life's tough . . . wear a cup.

  8. #8

    Join Date
    Apr 2018
    Location
    Knoxville, Tn.
    Posts
    153
    Post Thanks / Like
    I reported a QRM source playing loud bluegrass/country music on the Atlanta Center frequency, on a flight over the North Carolina side of the Smoky mountains. The ATC could not have been less interested. A week later on the return trip the interference was still there.

    I have also reported a loud, characteristic machine - like QRM sound over Nebraska on several occasions over the years. ATC always acts like they have never heard it reported before, but there are a lot of missile silos out there...
    Last edited by Tennessee; 11-15-2018 at 08:47 PM.

  9. #9

    Join Date
    Sep 2003
    Posts
    6,628
    Post Thanks / Like
    Those are just the installation manuals. As far as I can tell, the GTR-200 comes with RF squelch set at zero, and we re-set it at 10.

    It is not really dangerous - the tower overrides it. But it is seriously loud when the tower is not transmitting - it is uncomfortable. Today was particularly bad - there were islands of interference everywhere. It does block intercom use - fortunately it is not a problem in the flare, where I need to be able to communicate (POWER!).

    How do we locate the sources? Their location is painfully and indelibly imprinted, with exact boundaries that we can avoid.

  10. #10
    BC12D-4-85's Avatar
    Join Date
    Feb 2016
    Location
    Fairbanks, AK.
    Posts
    1,498
    Post Thanks / Like
    Quote Originally Posted by bob turner View Post
    Those are just the installation manuals. As far as I can tell, the GTR-200 comes with RF squelch set at zero, and we re-set it at 10.
    Yes that's correct and they describe how to adjust the squelch threshold.

    But seriously Bob just have a look at where you're operating. Surrounded by San Diego's finest RF generators. Go to the VW and Mercedes lots I seen on Google Earth and have a RF sniff with a handheld. That should tell you something about the sources especially if you can walk up to the peak spot. It it hits hard w/o the antenna attached you've found it. You may also as suggested compare the GARMIN units with others for basic interference rejection.

    Gary (who lived across the street from a former 50K watt AM broadcast tower)

  11. #11

    Join Date
    Sep 2003
    Posts
    6,628
    Post Thanks / Like
    I just double-checked. For the GTR-200, factory is zero, and increasing the value increases the power required to break the squelch. Ten is apparently max squelch. The Stearman antenna is on the belly, making that one worse. I will double-check the SL-40 tomorrow - its range is 25-100, but they don't say explicitly that increasing the # increases the squelch.

    I understand flying past a nest of broadcast antennae - we have them on famous Mt Soledad - they blast through no matter what. I think we are dealing with walkie talkies or something.

  12. #12
    BC12D-4-85's Avatar
    Join Date
    Feb 2016
    Location
    Fairbanks, AK.
    Posts
    1,498
    Post Thanks / Like
    This is radio fun for me but I understand the frustration. What's the interference sound like? Can you record the events? I bet you can drive around with the vehicle's AM radio playing or use a VHF aircraft handheld and find them. Maybe not in heavy traffic but in off hours. It's worth the effort to find the source(s). The FCC won't set down their coffee for that.

    Edit: Take a handheld radio in the plane next time and see if it reacts the same as the onboard rig?

    Gary
    Last edited by BC12D-4-85; 11-15-2018 at 10:14 PM.

  13. #13
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Bozeman,MT
    Posts
    10,345
    Post Thanks / Like
    I once did some flying out of Tucson International. Any time we were in the pattern on the west side of the field, Super loud C/W broadcast drowned out everything. I asked one of the guys who worked there, and he said the interference had been reported frequently, with no results.

    And it was LOUD.

    MTV

  14. #14

    Join Date
    Sep 2003
    Posts
    6,628
    Post Thanks / Like
    Yeah - painful. Ours is white noise. But there is no telling whether the source is white or maybe it is just driving the IF into oscillations. I agree - the FAA and FCC won't put their coffee cups down.

    Fortunately our controllers are now helping - we get crosswind turns inside the Cherokees that need two mile upwinds. Yippee!

Similar Threads

  1. External Loads
    By SJ in forum Tips and Tricks
    Replies: 27
    Last Post: 09-07-2012, 09:20 PM
  2. 12 VDC External Pwr.
    By Aviator in forum Modifications
    Replies: 20
    Last Post: 11-27-2010, 04:59 PM
  3. External Loads
    By mvivion in forum Take Action Jackson
    Replies: 14
    Last Post: 04-02-2006, 06:42 PM
  4. External Loads
    By floats in forum Cafe Supercub
    Replies: 1
    Last Post: 01-03-2006, 09:37 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •