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[WARNING] EMI detected in 2010 Prius

Discussion in 'Fred's House of Pancakes' started by bwilson4web, Dec 25, 2016.

  1. bisco

    bisco cookie crumbler

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    driving deaths were up, hospital visits were up, minors using were up, a few other things. but there was a caveat with each one on fact check .org, so, while it looks bad on the face of it, more data will need to be collected.
     
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  2. Trollbait

    Trollbait It's a D&D thing

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    I think a spike in things is expected because of the novelty with few places to use it being legal, which raises the question of what is happening is because of increase in use or just an increase what gets reported since people aren't worried about getting caught now. Like increases in autism being from better diagnosing.
     
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  3. fuzzy1

    fuzzy1 Senior Member

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    Driving deaths are up throughout the country, not just in the couple of states that legalized it.
     
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Safety sells!

    Nobody lives forever but we can avoid some risks.

    Bob Wilson
     
  5. RCO

    RCO Senior Member

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    What! You're telling me I'm still in the line? :eek:
     
  6. bisco

    bisco cookie crumbler

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    driving death's due to marijuana and other drugs.
     
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  7. bwilson4web

    bwilson4web BMW i3 and Model 3

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    And sleep apneia and poorly managed diabetes.

    Bob Wilson
     
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  8. bisco

    bisco cookie crumbler

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    and talking and texting.
     
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  9. RCO

    RCO Senior Member

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    and laughing at CC's previous outbursts
     
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  10. Former Member 68813

    Former Member 68813 Senior Member

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    Pardon my ignorance, but what is your definition of EMI? Exposure Model for Individuals or Exact Monthly Installments?
    You probably don't mean Electromagnetic Interference because you wouldn't use magnetometer to measure it the same way you wouldn't use DC meter to study AC (very basic physics principles). Besides, Electromagnetic Interference deals with electronic noise and not health issues (duh!).

    It's my understanding that the biggest source of low frequency magnetic waves in cars are rotating tires with magnetized steel belts: https://web.ti.bfh.ch/fileadmin/home/mik1/Magnfields_HPJ_revision.pdf

    BTW, when I used my electromagnetic field meter in a stationary prius, the highest readings were in the driver footwell and right rear seat. Higher than my non-hybrid cars, but not by a huge amount. YMMV, and no, i don't have any health issues from EM field. My workplace has much stronger EM field.
     
  11. bwilson4web

    bwilson4web BMW i3 and Model 3

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    ElectroMagnetic Interference, the time changing electrostatic and magnetic field occasionally mentioned as have a health impact. Just as there are magnetic coil antenna, using a MEMs magnetic detector has as much utility as a dipole. Those of us to studied Faraday Laws know they are both quite capable of picking up a field. The only open question is sample interval.

    Now if you have a specific bandwidth limit or frequency requirement to measure, we can go back to the manufacturer chip-set and read out their specs. I know this particular instrument has a much higher sampling rate compared to the recording rates, up to 200 Hz. So we can get a sample set of the amplitude although the frequencies would likely defy analysis. This is not a spectrum analyzer.

    Now given our bodies are encased in a multi-layer, skin with significant attenuation within a millimeter or two of the surface, I suspect the biological effects are limited to frequencies within the range of this instrument. Of course, your mileage may vary.

    It wasn't clear that any particular area around the driver is important for measuring the EMI field strength. I suppose we could do:
    • top of head
    • forehead
    • left and right ears
    • rear of skull
    • left, right, front, and rear neck
    • chest center
    • back center
    • groin
    • upper thighs, top, bottom and sides
    • upper arms outside, front and rear
    Would that meet the requirements?

    Bob Wilson
     
    #51 bwilson4web, Jan 10, 2017
    Last edited: Jan 10, 2017
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  12. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The car body should act as a Faraday cage, so I suspect any tire EMI would stay outside.
     
  13. Former Member 68813

    Former Member 68813 Senior Member

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    since frequency is obviously important, especially for real EMI, what frequency did you measure, Bob (LOL)?

    looks like "should" is good enough for you. why don't you check for facts?
    hint: Faraday cage is for EM waves and not magnetic fields. we are not really talking about EMI here. Bob used that term in error.
     
  14. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    My understanding of what a Faraday cage does, includes electromagnetism, but not static magnets.

    Faraday cage - Wikipedia

    Bob is an engineer, I am much more theoretical. (Old , fat, and immobile. Although about a month ago I had a bone fragment removed from my right knee, so I may be much more mobile once Physical Therapy is done.)
     
  15. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I made no attempt at frequency measurement but just sampling the magnitude of field variations. In effect the changes of the magnetic field strength.

    In the meanwhile, I sent a note to the manufacturer asking for the full technical specs. This will give us an idea of the sample duration, not a frequency metric, but one whose inversion tells us the highest frequency it can detect:
    MPU-9250, 9-Axis Gyro+Accel+Magn, InvenSense Inc.



    There is another approach. The part has a fairly high sampling rate accelerometer and gyro. I can strap the unit to the non-powered, wheel hub, turn it on and roll down a hill to slowly increase the speed. The accelerometer/gyro can tell the rotation speed and I can compare it to the magnetic data. There will come a point when the magnetometer data will 'smear' and put an upper limit on the shortest sampling error.

    Bob Wilson
     
    #55 bwilson4web, Jan 10, 2017
    Last edited: Jan 11, 2017
  16. RobH

    RobH Senior Member

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    A little actual scientific data about a cancer cluster and measured EMF.

    Chapter 8 of Dirty Electricity covers a cancer cluster at a school in California. There were 18 cancers experienced by 16 teachers. The incidence at similar nearby schools was 1-2. Dr. Milham got involved after a whitewash job that claimed no excess cancers.

    The Graham/Stetzer EMF measuring device was invented by Professor Martin Graham and Dave Stetzer. It displays the average rate of change (dV/dT) of high frequency voltage transients. While most homes or businesses read under 100 G/S units, the school buildings averaged about 700 G/S units. Ideally, readings should be under 50. The meter gives an overload indication at 2,000 G/S units, and many of the outlets were overloaded.

    The following figure shows both the 60 cycle signal, and the noise imposed on it.

    [​IMG]


    Quoting the findings of the study:

    Sixteen schoolteachers in a cohort of 137 teachers who had ever been employed from <the school's> opening in 1988, through December 2005, had been diagnosed with eighteen cancers. (Two teachers each had two cancers). The observed-to-expected (O/E) risk ratio for all cancers was 2.78, while the O/E ratio for malignant melanoma was 9.8. Thyroid cancer had a risk ratio of 13.3, and uterine cancer had a risk ratio of 9.2. All of these numbers represent elevated risks. Most EMF-cancer studies measuring power-frequency magnetic fields almost never find risk above 4.

    What we discovered surprised us. Contrary to all of the recent research published on EMFs, the 60-Hz magnetic fields showed no association with cancer incidence. The new exposure metric, high-frequency voltage transients known as dirty electricity did show a positive correlation to cancer incidence. In addition, a cohort cancer incidence analysis of the teacher population showed a positive trend of increasing cancer risk with increasing cumulative exposure to high-frequency voltage transients on the classroom's electrical wiring as measured with a G/S meter. Cancer risk also increased with duration of employment.​

    The attributable risk of cancer associated with this exposure was 64 percent. Attributable risk simply answers the question of what percent of a disease is due to an exposure. This calculation subtracts the expected cancers from the observed cancers and divides that difference by the observed cancers. According to this calculation, a single year of employment at this school increased a teacher's cancer risk by 21 percent. A single year of employment in a room that had a G/S meter overload increased a teacher's cancer risk by 26 percent. These cancer risk estimates are probably low because twenty-three of the 137 members of the cohort were lost to follow-up. They were counted in the expected cancer risk calculations, but could not add cancer cases.

    ...

    A peer-reviewed paper reporting our findings was published in 2008 in the American Journal of Industrial Medicine (Milham & Morgan 2008)​

    Note that this study was about the cancer impact of high frequency transients on ordinary 60 cycle power. I'm not aware of any measures with the G/S meter of the Prius, let alone any other vehicle.
     
    #56 RobH, Jan 11, 2017
    Last edited: Jan 11, 2017
  17. bwilson4web

    bwilson4web BMW i3 and Model 3

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    It may be time to review Faraday's Law as applied to ferrite core antenna: RADIO-TIMETRAVELLER: An Unassuming Antenna - The Ferrite Loopstick

    Radio waves have both an electrical component (E) and a magnetic component (H). They are 90 degrees in relation to each other and also 90 degrees out of phase. Looking at a signal eminating from a typical vertical AM broadcast tower, the groundwave electrical component (E) is vertical, or perpendicular to the ground like the tower, and the magnetic component (H) is horizontal, or parallel to the ground. Receiving antennas respond mostly to one component or the other: small, closed loop (less than 0.1 wavelength in wire length) antennas to the magnetic component, open-ended wire antennas and large, closed loop antennas to the electrical component.
    [​IMG]

    What this means is an electronic wave can be measured either by looking at "dV/dt" but also "dB/dt". where B is the magnetic field.
    [​IMG]
    (from Wikipedia: Faraday's law of induction - Wikipedia)

    Detecting the magnetic component is just as valid and that is what this part does:
    MPU-9250, 9-Axis Gyro+Accel+Magn, InvenSense Inc.


    I know, this is hard stuff. You have to understand calculus to even interpret the formula and understand its implications. Yet it is how all radios and how ElectroMagnetic Interference (EMI) exists.

    Going back to the original question about measuring frequency, I'll mount the part on a wheel, enable it, and coast down a hill. As the car speed increases, the accelerometer, gyro, and magnetic sensor data will be recorded. We can then analyze the data to see if the magnetic strength changes as a function of rpm. This will tell us the upper limit of measuring a fixed frequency.

    Bob Wilson
     
  18. Former Member 68813

    Former Member 68813 Senior Member

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    Bob, you didn't have to answer, it was a rhetorical question. Your measured frequency was (much) less than 1 Hz, see my previous DC analogy.
     
  19. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Sorry, I sometimes miss the clues. It isn't intentional ... just the way I am:
    [​IMG]

    Bob Wilson
     
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  20. Former Member 68813

    Former Member 68813 Senior Member

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    To be fair one needs to put it in context. My son did a science fair project where he planted different seeds at various distances from wi-fi network antenna. Some plants struggled to germinate while some others grew faster (anyone can replicate it). My take is different species or tissues can react differently to different wavelength of RF EMF. As a matter of fact, low frequency EMF is FDA approved for bone fracture healing (see PEMF).