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  1. #21
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    Default Re: electromagnetic pollution caused by tablets

    thatcomicsguy, thanks. Now I understand your post much better, and appreciate your efforts which allowed you to give us such a well-grounded explanation.
    +1 rep

  2. #22
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    Default Re: electromagnetic pollution caused by tablets

    funny my old post lives again =)
    nice informations thatcomicsguy! thank you!

  3. #23
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    Default Re: electromagnetic pollution caused by tablets

    I was recently asked this question via private message, and I seeing as I had come up with new information, thought it would be worth posting in this (old) thread. I've scrubbed the original poster's ID from the quote.

    Have you tried measuring the EMF from Wacom tablets? [. . .] I tried holding a radio scanner to the screen of a tablet PC, tuning to 500-600 kHz, and using AM/FM/WFM, but didn't find anything yet. Assuming it operates on something like 531 or 600 kHz, most of the EMF meters I can find for under $300 don't seem to be sensitive at that frequency for measuring purposes.
    It's a tricky problem, since Wacom isn't forthcoming with any hard figures.

    I found some numbers when looking through the Wacom patent information. . . (The earliest patent was filed in 1989, and it is the only one which indicates actual frequencies broadcast by the digitizer.)

    That basic tablet design uses a 500 Khz carrier to transmit a modulated 15.625 Khz scanning signal which powers the stylus. (That is, the 500 Khz signal turns on and off 15.625 thousand times per second).

    So that's the frequency range. I don't know what 500 Khz or 15.625 Khz does to the human nervous system. And since I don't especially want to find out through direct experience. . , I'm interested in the power level at which those frequencies are being broadcast from the surface of my computer screen.

    The power level is really the important thing here.

    Unfortunately, I've not had the opportunity to play with a meter, but other people have. One of whom is a Cintiq and Intuos user.

    According to that poster who wrote on another forum the power level output was 60 to 70 milligauss on an Intuos 2. He didn't note the distance at which he measured, so I'm going to assume he took the reading at 1 inch from the surface of the tablet.

    And so. . , using inverse square law, (or this handy calculator) we see when taking the high-end reading of 70 milligauss, that at a distance of 12 inches, (which is the closest my eyes ever get to the tablet surface when I'm leaning close), the power level drops to .45 milligauss. For the center of my head, assuming that my skull and other biomass doesn't dampen the field at all, (which of course, it does), then at around 16 inches, the signal power drops to .273 milligauss.

    EDIT******* The above math is totally wrong, because it assumes that the radius of the emitter source is 1 inch, which it is not. Rather, the emitter is the flat surface of the Wacom tablet, and its area of emission is not spherical. The inverse-square law only works when you pull back from the source a significant distance.

    According to Doctor Mercola's website regarding EMR pollution, .5 milligauss is considered (on average) to be the safe limit. Nobody knows for certain, of course, but all in all, especially compared to other electronic devices, that exposure seems a pretty good bet to me, and I've decided that the risk is worth the gain.

    Of course, this is all just based on my best efforts using Google. I may be missing pertinent information. I would appreciate it if Wacom would give us some clear figures on their various devices. The fact that they do not is probably an executive decision; any information offered at all would invite controversy, which I'm sure they are happy to avoid.

    I have one thought to add, however. . , given that laptop makers are so eager to boost battery life, I suspect that some thought was given to making the digitizers in the Penabled line common to Tablet PCs as low-power as possible. It is *possible* that the Wacom hardware in Tablet PCs emit less energy than other models, like the Cintiq or Intuos, but that's pure speculation on my part. And as per usual, Wacom isn't saying a thing.
    Last edited by thatcomicsguy; 08-09-2011 at 03:23 PM.
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  4. #24
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    Default Re: electromagnetic pollution caused by tablets

    Thanks for the anonymity, I don't mind taking it public though.

    Wacom directed me to a page about EMR technology.

    On their forum is a question about radiation with this reply:

    The electromagnetic communication between tablet and pentip is a low power and low distance field. (The tablet typically uses less than 65 mA at 5V, which means about 0.325 Watt. Most of this energy is used to power the electronics in the tablet, as small percentage is used for the electromagnetic field of the sensor.) It has no negative effect on health.
    7Ray7777 seemed to use this meter:



    ... wacom Intous 2 ... full tilts the needle in the 0 to 3 milligauss range and comes close to pegging the high level of the meter reading (0-100 milligauss) it comes in at 60 to 70!
    As you can see that reading is in regard to the AC magnetic field, but doesn't seem to tell us anything about the radio waves. The specs for that band is:

    Frequency Range: 40 Hz 100 KHz (see frequency weighting)
    Accuracy @ 60 Hz (50 Hz): +/- 20% of reading
    Range/Resolution (@ 60 Hz or 50 Hz): 100 milligauss / 0.2 milligauss
    For radio waves, it is sensitive to 50 MHz 3000 MHz (3 GHz), which is far from the 500-700 kHz area Wacom is supposed to operate. There is another Trifield meter that has extended range, which can measure 0.1 MHz 2500 MHz, which is what we'd need. It seems to be the only meter I can find that's somewhat calibrated, and might possibly provide some useful data for under thousands of dollars.

    If no other meter can be found, I'll purchase this one. I have several tablet PCs, and intuos tablets, including the intuos4 Extra Large, which I can get measurements from. The specs on the Trifield Broadband Meter don't satisfy me though, so I'll keep looking for more.

    I'm mostly interested in the field strength, not frequency or power usage. I find it suspect that this data is not provided anywhere, even upon request. I have been in close contact with Wacom EMR in one form or another for up to 10 hours per day, for 10 years.

    As one of the first children to be exposed to excessive amounts of PC technology, many years of which were uncomfortable CRT monitors in close proximity, I fully expect to die early or suffer negative consequences. I already do, but not from EMF yet AFAIK.

    I'm curious now, so I'll do anything in my power to get us a solid answer with actual numbers. Maybe a local power company or university would have better equipment to measure the field strength more accurately. But the meter might tell something.

    Thank you for the info, that old post was pretty much the only thing I could find on the subject. Regardless of whether the numbers are high or low, or if it's harmless or not, we have a curiosity, and it should be responded to. Wacom is disappointing here.

  5. #25
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    Default Re: electromagnetic pollution caused by tablets

    The electromagnetic communication between tablet and pentip is a low power and low distance field. (The tablet typically uses less than 65 mA at 5V, which means about 0.325 Watt. Most of this energy is used to power the electronics in the tablet, as small percentage is used for the electromagnetic field of the sensor.) It has no negative effect on health.
    That must be a standard response. I also ran across a comment on their forum, where they evaded the question with similar language and wrapped up with, "It has no negative effect on health."

    Nobody, (certainly not a Wacom public relations agent), is in any position to make such a declaration with authority. It would be very easy to find that kind of response insulting. I'd rather just know the numbers so I can determine the risk for myself, thanks.

    Anyway. . , one of the things I find challenging about this kind of research is that the units of measurement are not standard across every study, and often complex conversions need to be made.

    For instance. . , an AC magnetic field, and radio waves are essentially the same thing. (Radio waves are high-frequency pulses of a magnetic field). I'd not familiarized myself with Gauss being used as a means of measuring signal strength until today, and I still don't know how to convert it to Watts. Fortunately, others have compiled comparisons of EMR emissions from various electronics devices based solely on Gauss readings, probably as a result of such hand-held meters becoming popular.

    I would certainly be eager to see any results you come up with once you pick up your own meter! Having to work on second-guesses is frustrating, to say the least.

    -Cheers!
    Last edited by thatcomicsguy; 08-09-2011 at 01:47 AM.
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  6. #26
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    Default Re: electromagnetic pollution caused by tablets

    It's surprising they don't have a legal department advising them not to make statements like that. Imagine if there were mass health problems, wouldn't something like that make them more liable since they're not saying it's unknown, but that there are no negative effects? That seems irresponsible and gives false confidence. I don't need to be coddled to keep using their product, but I'd like the numbers so I can be aware. If people start getting cancer, at least we might have some clue what contributed to it, and can take steps to prevent it from continuing needlessly.

    The radio and magnetic fields are together, but I think we need to measure both because:

    All near-field readings require special attention. In general, readings taken closer than one wavelength require measurement of both the E and H fields. A good general rule of thumb is "Measure the E field above 300 MHz and measure both-the E field and the H field below 300 MHz". For example, when surveying radio frequency heat sealer machinery at 27 MHz (λ = 11.1 meters, or 36.4 feet), both E and H must be measured, since the measurement is in the near-field. Two wavelengths at 27 MHz is 22.2 meters (72.8 feet) away.
    But the only meter I've found that can measure around 600 kHz is the Trifield Broadband, and I don't really trust it to be accurate. There's the Lutron EMF-829, but it's not in stock and costs $600. If I can't find anything soon I'll just order the Trifield.

  7. #27
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    Default Re: electromagnetic pollution caused by tablets

    Jeezuz. This is a lot more complex than I'd originally thought.

    I just brushed up on EM field theory by reading this simple manual which was written for field technicians. (It's well-written and gives clear explanations of the various forces and terms commonly discussed, in language which is accessible for the common plebes. I'm glad I found it.)

    Anyway. . .

    Damn. In the 'near field', it seems to me that taking direct measurements of the exact points in space where your hands, head and torso are going to be in relation to a tablet is the only meaningful way to know what kinds of EM you'll be experiencing. Taking a few measurements and trying to extrapolate general conditions seems almost impossibly complicated; the inverse-square law evidently falls apart when you're so close to the emitter.

    It seems to me that the Wacom engineers must have been doing some really complicated R&D, (and probably a lot of hit & miss experimenting) to come up with working digitizers at all in the first place.

    The one thing I do take some comfort in is that the power levels are so low when compared to other electronics. The tablet is not a phone which is trying to send a meaningful signal to a cell tower half a kilometer away. Having a handset broadcasting that kind of power directly against your head is in a different league altogether when compared to a tablet antenna which only needs to charge coils in a stylus two inches above its surface.

    But now I am very curious to know some hard figures. What kind of tablet are you working with?
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  8. #28
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    Default Re: electromagnetic pollution caused by tablets

    I was using an intuos4 medium, but both mini-USB ports broke off inside the unit. When I opened it up, I saw there was no support, just a couple solder points to hold the wing-arms onto the board.

    My soldering station had vanished, so I was without a tablet on my desktop for several months, and now my mouse-hand is upset again. I considered trying a small tablet, but with large monitors there's not much precision, and it seems like it'd be too cramped compared to medium. Instead I just received an XL intuos4 today, which I wanted to experiment with to see if larger shoulder and arm movements feel more or less ergonomic.

    Using amplitude modulation at 600 MHz, I can hear tones with the antenna in close proximity to the Fujitsu ST5111 Wacom digitizer. If I move the pen in range, where you can hover to move the cursor, the lower pitched tone steps up in pitch. If I move it out of range, it returns to the original pitch. Buttons and movements don't seem to make any difference in sound.

    With the intuos4 XL, I can hear something similar at 528 and 703.95 MHz. Also 3.33, 4.66, 5.995, and 11.33 MHz. At the lower end, 666 kHz has signal and tones, and also a purring sound when I move the pen around the antenna.

    The tablet PC and intuos4 seem to operate at different frequencies, and their pens are not compatible with each other.

    The pens also don't work with the original Intuos from around the year 2000, and with that one there might be some activity around 495 kHz and 1.39 MHz, but I didn't spend much time looking in the higher frequencies.

    I don't know the math, but I think there's something like electromagnetic shadows from the center frequency, like harmonics. So I didn't list all those to mean that it uses those frequencies intentionally, but that's where activity was, with varying levels and patterns, so some of those might be shadows, and maybe one is the actual channel. I don't know, but my radio can't tune below 500 kHz, and it's not very precise at the low end.

    I emailed the contact for the Trifield meter, because I saw another one on their site that says it measures "power density", and I don't understand the difference. I was looking at different types of meters, and liked the idea of a spectrum analyzer, but couldn't find much. The Lutron EMF-829 looked better than the Trifield Broadband, at $600, but I could not find it at any stores.

  9. #29
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    Default Re: electromagnetic pollution caused by tablets

    I'm looking at the internals of the intuos4 medium, because I was curious if it's shielded from behind (a lot of people use them on their laps directly above genitalia), and I also thought it was possible a frequency could be printed on something in there.

    But you know what? There's not much here. It's just a big empty green board, with vertical striped traces on the board, and a small number of components on the sides. It's amazingly empty. Unless one of the chips is expensive, it looks like the material costs might be very low.

    There's a whiteboard looking sheet on the back, but I can't tell if it's an EM shield.

  10. #30
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    Default Re: electromagnetic pollution caused by tablets

    I received a response from someone at AlphaLab. They suggested checking Spectran.com for RF meters.

    The NF-5030, NF-5010, and NF-XFR seem to be the only ones that cover ~600kHz, and they're over a thousand dollars. But those are spectrum analyzers. For RF power meters, they start at 100 MHz.

    I get the feeling either I don't understand, and am false in the assumption that the RF at ~600 kHz needs to be measured too for the results to be valid, or most devices are not in that range so there is little demand for tools to measure. There are lots of meters available, but only a very select few cover half a megahertz. Most everything is either below or above that.

    Maybe I should email Wacom again and ask the frequency they use. Maybe those numbers about 5-600 kHz are old, and they're now using something more common, that happens to be in the higher range. If that were the case, it'd be far easier to find a lower-priced meter that would work.

 

 

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