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Thread: Electromagnetic radiation question

  1. #1
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    Electromagnetic radiation question

    Thereís 2 defined spots where my Harley wonít start. One is a parking area with no adjacent buildings but for some reason, if I push it 30 feet (12 meters) itíll fire right up.
    The other is also a parking lot, but within a cone of radiation from an electrical room where thereís breaker boxes galore, plus cell alarm panels and wireless electronic controls.
    It got me to thinking about, if my security on the bike was affected through a wall and 20 plus feet away, what is it doing to the people working in the kitchen adjacent to the room, or the people in the banquet halls.
    I know thereís more educated people here on this, so - as the house chair of the institution, should I be looking at a way to mitigate the rf radiation.
    Young enough to remember doing it;
    Old enough to wish I could do it again.

  2. #2
    How does the security on your bike work? If via simple radio transmission like bluetooth or whatever, all it would take to screw up your bike would be someone using a drone, or RC car, or ??? in the vicinity using a radio frequency close to whatever your bike is using. Otherwise, I haven't a clue...
    ========================================
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  3. #3
    Do you mean you can turn the engine over with the started button/key but the engine won't start? Or that the starter won't work to turn the engine over?

    Mike
    Go into the world and do well. But more importantly, go into the world and do good.

  4. #4
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    Harley security systems use a key fob and a receiving antenna module under the seat. Normally, the first indication the battery in the fob being weak, the bike won't start.
    But, the process is like this: Straddle the bike and pull it upright and sthe security system "polls" for the activating fob. If it can't find it the turn signals (in my case) begin flashing on/off, and the indicator lights on the dash light up. The bike is essentially "dead" at that point.
    There is a way of bypassing the security system by putting in a bypass code, but it's a pain.
    It's a well known sensitivity for many Harleys (mine's a 2009 Touring model), and they may have changed the problem in the newer models.
    When it happens once in normal riding, it's a reminder to replace your fob batteries, but I did so last week, and the fault occurred on Friday, with fresh batteries.
    Young enough to remember doing it;
    Old enough to wish I could do it again.

  5. #5
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    It sounds like the two locations have a transmitter on the same frequency which is jamming your fobs signal and when you move away the fobs signal can then overpower the local transmitter and it all works.

    Next time it happens try moving your fob very close to the bikes antenna to see if that overcomes the jamming.
    Last edited by Bohdan Drozdowskyj; 06-20-2021 at 2:20 AM.

  6. #6
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    It doesn't. My first action is to put the fob within 4" of the security module.
    Young enough to remember doing it;
    Old enough to wish I could do it again.

  7. #7
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    I had problems with the Liftmaster garage door opener remotes. The good old style ones just worked but when I put new openers on my garage about 10 years ago the range was terrible. At times they wouldn't even work standing right under the opener. I ended up swapping out the wired button inside the garage that now receives the signal from the remote. The range isn't great but it's good enough so the door will be open by the time I'm ready to back in. I tried several things, like a range extender, that just didn't work. I think around 2010 the remotes were inferior. My guess is that there was a push to go to a digital signal. They just didn't filter out external signals very well. The odd thing is I live a 1/4 mile from anyone else on top of a hill. There shouldn't be much of anything unusual around me. if possible I would see if Harley has an upgrade kit for it.

  8. #8
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    Quote Originally Posted by Aaron Rosenthal View Post
    .. - as the house chair of the institution, should I be looking at a way to mitigate the rf radiation.
    That sounds like potentially a much more important question than why the Harley won't start. Even if there is no actual potential health risk, the suggestion of one combined with someone's unfortunate circumstance can be a serious problem.

    You can buy a field strength meter for $100-200 or so and walk around with it (surreptitiously if you're smart) and see if readings there are different from other locations, even if you aren't qualified to interpret them. Then decide if you need to talk to someone who can do that.

    Years ago I remember concerns at the tech company I worked at when there was a high-traffic area sharing a wall with the room with the file servers. Don't know what they did about it - I left soon after.

    Once you have a field strength meter, you can alarm yourself by noticing how strong the EMF is right where you stand in front of your microwave, among other places.

  9. #9
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    Quote Originally Posted by Alex Zeller View Post
    I had problems with the Liftmaster garage door opener remotes. The good old style ones just worked but when I put new openers on my garage about 10 years ago the range was terrible. At times they wouldn't even work standing right under the opener. I ended up swapping out the wired button inside the garage that now receives the signal from the remote. The range isn't great but it's good enough so the door will be open by the time I'm ready to back in. I tried several things, like a range extender, that just didn't work. I think around 2010 the remotes were inferior. My guess is that there was a push to go to a digital signal. They just didn't filter out external signals very well. The odd thing is I live a 1/4 mile from anyone else on top of a hill. There shouldn't be much of anything unusual around me. if possible I would see if Harley has an upgrade kit for it.
    I installed a liftmaster opener and had the same problem. I ended up extending the antenna wire out the door and now I can open from almost 1/4 mile away

  10. #10
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    RF "stuff" can be interfered with in many different ways, but two of the most common are: 1) a low energy signal that is very near the operating frequency and mode of the device in question and 2) a high energy signal that isn't necessarily close in frequency but is strong enough to overload the circuitry in the device. In the first case, the interfering signal looks like a valid signal that just doesn't have the correct information content. In the second case, the devices circuity is overloaded and it just becomes unable to process any valid signal at all.

    Your two dead spots could be one example of each of these. The case where you are near a building with a lot of gear could be the first case. Electronic gear individually has to meet FCC limits for emitted energy, and usually, but not always, those limits are low enough to prevent interference. The limits are of course, statistical in nature because actually testing every device against every other device is just not possible. An when you have a bunch of devices in close proximity, the chance of them causing interference goes up quickly.

    In the case where there is no nearby building, my first suspicion would be any nearby cell tower or any other nearby broadcasting or transmitting equipment. These can emit signals of high enough energy to overload many simple RF devices if you happen to be in the wrong place.
    --Certainty is the refuge of a small mind--

  11. #11
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    Is there a hospital nearby? The lastest and greatest MRI machines have a magnetic field roughly 3x the strength of planet Earth. When I park at the hospital the remote for my truck only works when I am within about ten feet of the truck; when I am home I can lock/unlock from 60-75 feet easy. When I am a quarter mile away from the hospital my remote can reach 30 feet.

    Just an idea. Utility company substation with a bunch of transformers nearby?

  12. #12
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    Do you by chance have another key fob in your pocket? I hang my keys from a carabiner on a belt loop, and I have an ‘18 Indian Chieftain that uses a keyless ignition fob. I found that if that fob is on the carabiner next to the fob for our ‘17 Explorer (with keyless ignition), the bike sometimes loses track of the fob while riding (it just flashes a warning on the screen). If it’s in my pocket just a few inches away from the other fob, I don’t have issues.
    Jason

    "Don't get stuck on stupid." --Lt. Gen. Russel Honore


  13. #13
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    Here is what my research has uncovered.
    The item radiating RF wavelength works on 434 MHz (as a round number). Since it's a wireless remote control for switching on & off lights in this case, the radiation broadcasts 360 deg.
    The key fob also uses the same frequency but it only has a range of ~4 feet. Because in the best of circumstances the battery in the fob starts at 3 volts and is constantly running down, because it's always polling for the security antenna, the electrically powered light controller easily overpowers the signal generated by the fob.
    Solution; Shield the controller or park the bike elsewhere.
    Young enough to remember doing it;
    Old enough to wish I could do it again.

  14. #14
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    Quote Originally Posted by Scott Winners View Post
    Is there a hospital nearby? The lastest and greatest MRI machines have a magnetic field roughly 3x the strength of planet Earth. When I park at the hospital the remote for my truck only works when I am within about ten feet of the truck; when I am home I can lock/unlock from 60-75 feet easy. When I am a quarter mile away from the hospital my remote can reach 30 feet.

    Just an idea. Utility company substation with a bunch of transformers nearby?
    The most common MR scanner has a magnetic field strength of 15,000 gauss or 1.5T. The magnetic field strength of the earth though currently being reargued, was accepted to be approximately 0.6 gauss. Thus the most common MR scanner has a magnetic field strength that is approximately 25,000 times the earths magnetic field. The early MR scanners required specially built rooms with 3" of specially annealed steel to make it become "mu metal" in the walls to contain the majority of the magnetic field to the scan room. The newer MR scanners have special reverse wound magnetic coils within the magnet to make them "self shielding" and maintain the vast majority of the magnetic field within the scan room.

    3T and higher strength magnets were becoming more common before I retired 10 years ago.
    Last edited by Ken Fitzgerald; 06-21-2021 at 7:09 PM.
    Ken

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