by / Thursday, 25 June 2015 / Published in Healthy Building Inspections & Testing
Magnetic Field Map Sausalito Golden Gate Bridge North SF

EMF and GPS Syncing Capabilities – Magnetic Field Example

Quite honestly, one of the aspects of my job that I love is to test new technologies or to further develop the capabilities of our company. One of the skill sets that we have better developed lately has been to sync our various EMF meters with GPS location tracking to allow for investigations of properties and large areas.

As it should happen, my schedule called for extensive driving that day and it occurred to me that it would allow an excellent example of syncing a Gaussmeter with GPS path tracking to be made.

The route made for that day is shown by the blue line on the map below. The route went from Walnut Creek, up to Sacramento, back down to San Rafael, down 101 South through San Francisco to San Mateo, back up 101 North to come across the Bay Bridge and up 24 to return to Walnut Creek area.


EMF & GPS Mapping – San Francisco to Sacramento

EMF and GPS – Magnetic Field Mapping

Dropping the Gaussmeter datalog into a GPS syncing program and establishing the magnetic field strength as an elevation, allows us to see that the power lines along the West Sacramento highway corridors are apparently pulling more current than the Central and East Sacramento sides. This was also due to the time of the day at which this track was made. Driving at very early in morning the lighting loads of the city were still at their high point before dropping with the morning light. The various electrical systems of the car caused some magnetic field in and of themselves, however they were cancelled out by focusing on the 60 Hertz magnetic field influence. The maps below show only the 60 Hertz magnetic field influence on the car as it was driving this route around the Bay.


EMF & GPS Magnetic Field Map Sacramento

Another area that showed relatively high levels of 60 Hertz magnetic fields was the area from Sausalito across the Golden Gate Bridge and into North San Francisco as shown below.


Magnetic Field Map Sausalito Golden Gate Bridge North SF

EMF and GPS – Magnetic Fields on Golden Gate Bridge?

Driving through San Francisco showed a few spikes, however on the return coming back over the Bay Bridge showed that very little 60 Hertz magnetic fields were present along the Bay Bridge.


Magnetic Field Map Golden Gate Bridge SF Bay Bridge

Most EMF Inspection clients do not ask us to map out huge routes like this. Using these and other meters we are capable of mapping out perimeters and cross-sections of large properties for low-frequency Electric Fields and Magnetic Fields, and Radio Frequency power densities from 27 MHz to 10 GHz.

Give a ring or send a note if you want your neighborhood or property surveyed for EMF or EMR.


10 Responses to “EMF and GPS”

  1. Alex Stadtner says :

    Hello Katy,
    Good question. It’s not a very controlled experiment and some 60Hz magnetic fields were probably coming from both the car and exterior sources – mainly power lines.
    The metal in tires and wheels spins quickly and apparently generates magnetic fields. Karl Riley wrote about that in his book about dirty electricity.
    The electronics in some vehicles can produce a lot of 60 Hz magnetic and electric fields. We’ve found some vehicles worse than others.
    Good luck in your quest for a low-EMF environment,

  2. Katy says :

    Hi Cameron,

    Is the 60Hz measurement coming from your vehicle, or coming from surrounding traffic?

    Reason I am asking, living within a certain distance of freeways makes a child more likely to have autism. I came across your page while trying to figure out whether all the vehicles moving at a certain pace on a freeway might create their own EMF. Is this possible?

    from Katy

  3. Alex Stadtner says :

    Most GPS units are just receivers of satellite transmissions. As receivers – like a standard clock radio – they do not emit radio frequency (RF) radiation. In terms of radio frequency emissions in a car, I’d pay more attention to all the bluetooth devices. Bluetooth is constantly “pinging” RF emissions trying to find a pair up with mobile devices. Best if you can disable or turn off any bluetooth in a vehicle.

  4. Welming Chen says :

    Does the GPS in cars emit EMF ‘on their own’? i.e. Am I exposed to less EMF if I choose a car without GPS? Or is the EMF mostly dependent on the EMF specific to the location?
    Thank you!

  5. Danny Lee says :

    I like Alex’s idea about Google using their mapping cars to create overlays for air quality and EMF. Could take the realms of feng shui and geopathic stress to a whole new level. Might even reveal some interesting snippets of information about ley lines, if you believe in that sort of thing. Just out of interest – how big is a gaussmeter with a built-in low-frequency spectrum analyzer?

  6. Alex Stadtner says :


    Thanks for the reply. It helps clear things up for me.

    Note to self: never doubt Cameron’s EMF savvy!

    I believe the magnetized wheel phenomena can eventually be picked up by an AC gaussmeter, because the wheels are in motion while driving. The frequency (Hz) may vary with speed (revolutions per minute). Sam Milham wrote about this in his book about dirty electricity. Could be wrong. But I think you’re right in isolating the frequency to only 60 Hz. That should knock out the vast majority of other odd-ball variables that could throw off the measurement.

    And I was thinking about the high magnetic fields on the Golden Gate Bridge, too, and came to same conclusion. There must be some high-voltage power lines under the roadway. Too bad they didn’t locate them closer together, or drop them down a little further under the roadway and sidewalks. That’s what they get for not consulting us first. =+)

    Have a great weekend, and I look forward to a future RF map of the region! In fact, a blog about “EMF mapping” that included what you can do to overlay measurements over a bed, or in a chair, and syncing the meter to a GPS would be a very interesting read. Love the visuals.

    Thanks again,

  7. Cameron says :

    Ah, but Alex! Have you no faith in my mad EMF skilz? 😉

    As I described in the blog, I isolated the 60 Hertz low-frequency Magnetic Fields for measurement. Cars do give off magnetic fields but only very rarely at 60 Hertz exactly. You cannot do this with a standard AC gaussmeter, as they do not differentiate the frequencies of the magnetic fields. The gaussmeter I used has a built-in low-frequency spectrum analyzer which enables me to differentiate the various magnetic field frequencies. I can tell when the car was accelerating because upon acceleration a distinctive >2 kiloHertz magnetic field was noticeable. Many of the other components in the car operate at various frequencies as well, but almost none at 60 Hertz, except when a Inverter is installed (which this car didn’t have). A normal gaussmeter would certainly show magnetic fields in vehicles when parked because it cannot differentiate which frequencies should be isolated as pertinent. This high-quality gaussmeter allowed me to isolated the exterior influencing 60 Hertz magnetic fields for study.

    Magnetization of the metal in tires would be a DC phenomenon and would not be measured by AC gaussmeters.

    As you accelerate or decelerate through a magnetic field there is some distortion of the AC magnetic field strength. I am not driving a Lamborgini though (Note to self: Ask Alex for a Lamborgini test car… for ‘research purposes’) and I am, quite honestly, kind of a Sunday Driver. There may have been a +-10% change in the magnetic field strength with sudden acceleration or deceleration. Definitely not enough to account for the magnetic field experienced on the Golden Gate Bridge. Much more likely I was driving a lane on the bridge that has some sort of power line under the road deck.

  8. Alex Stadtner says :

    Just occurred to me how easy it would be for Google to outfit their mapping cars with other environmental monitoring equipment. They could create some amazing overlays for air quality and EMF.

  9. Alex Stadtner says :


    This is a really innovative way of combining two technologies to create accurate EMF maps. It really helps visualize what’s happening at a city/neighborhood scale. I can see how it would be helpful if a client was trying to find a low-EMF area, and in theory could be used to map both low-frequency magnetic fields and Radio Frequency (RF) radiation. Really cool stuff!

    My one question is about measuring AC magnetic fields in a moving vehicle. I’m just not 100% certain that using a standard AC gauss meter is the right approach. I’ve read some about the magnetization of the metal in tires over time, and I’ve seen my magnetic field meter go nuts in some vehicles even when parked. There’s no denying there was a lot of variation in magnetic field densities across the San Francisco Bay Area, but might some of the variation be explained by the different speed at which you were traveling when you took the measurements?

    I can certainly see how walking around with the GPS and EMF meters would be useful at a smaller scale, but in the car I wonder how accurate the magnetic field measurements are. Any thoughts appreciated.

    RF maps would also be very interesting. But, again, at a city/driving scale it would be tough because every car driving by with an active cell phone or bluetooth device would give a temporary spike. I’m sure that exterior stationary sources like cell towers and radar would be the highest spikes. Hope to see RF mapping in a future blog.

    Really fantastic EMF images.

    Thank you,

  10. A Stokes says :

    Fun to see this innovative approach combining EMF and GPS. Nice work Cameron!

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