| T O P I C R E V I E W |
| 3amado3 |
Posted - 05/21/2019 : 08:25:05
Just got my new toy and am trying to learn what it’s telling me!
For the most part my main concern is testing the router (trying to limit wi-fi exposure). I’m testing it in the all-in-one mode and if I stand right next to the router the RF hits around 2000 mW/m^2. If I move 5 feet away it drops to the 15mW/m^2 range. If I go directly up a floor it’s all the way down under 1mW/m^2 for the most part. In the bedrooms another floor up it’s about .001.
Is this telling me there is basically no RF radiation reaching the bedrooms? But how come I still get a couple of bars on my phone for wi-fi reception? Or more specifically a wi-fi analyzer app lists the signal at about -60 dBm (it gets down to -15 dBm right next to the router). Is there some other type of wave other than the RF radiation that I should also be considering/measuring if I want to test the wi-fi safety of my house? Clearly it's reaching the bedrooms but the 390 doesn't say that.
Second question, which column in the below link translates to the mW/cm^2 and mW/m^2 that I have the option of displaying in the 390? Is it literally mW/cm^2 and W/m^2. I was looking elsewhere for safe levels and things were listed in V/m and uW/cm^2 and some of the numbers seemed strange when I converted to what the 390 was saying so I just wanted to be sure. (and the card that came with it switches between uW/cm/^2 and mW/cm^2 for listing it's levels which seem confusing)
h**p://www.hypercable.fr/images/stories/Conversion_Chart_dbm_v_m.pdf
Third question, if I’m just trying to sort out the RF (we live in the suburbs away from towers, just want to measure the wifi impact), which is the best view to use? They seem to give different results. Standing a couple feet from the router the All in one view says about 30 mW/m^2. Or .004 mW/cm^2 (that setting seems pointless, it barely registers even right next to the router). Then if I switch it to RF Browser there is a number in the upper right corner that is continually changing and in the 30mW/m^2 range, but also a number in the upper left corner that changes less often and in a higher mW/m^2 range typically (say 50+). Then if I switch it to the RF Spectrum, I have no idea what this is saying. I have it set to the 2.4-2.5 Ghz but it doesn’t list numbers in mW/m^2, it just has a Chn number in the upper right, dBm’s at the bottom and continually changing pW’s in the upper left.
Sorry for the long post, Thanks for any help!
(shocking how much RF baby monitors give off, those have been shut down….)
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| 14 L A T E S T R E P L I E S (Newest First) |
| 3amado3 |
Posted - 02/21/2020 : 11:40:45
Edge of the screen issue: My photos higher in the thread must've expanded it.
Oh yes, guess I should pay closer attention to feet vs inches!
Luckily it's a grade school and there isn't as much phone/computer usage. Plus I'll be going up there after-hours when it will hopefully be mostly wifi and the security cameras that I saw.
If I calculate correctly, you are saying 1 mW/m^2, yes my phone definitely spikes over that during use, but at least when it's just sitting there on my desk (which is obviously the bulk of the time), it is considerably below that. But agreed, this is all a big problem! |
| rfrazier |
Posted - 02/21/2020 : 10:22:55
I guess my question wasn't clear. Sorry. On my screen, the lines of text in this post are 3 times wider than the screen. I have to scroll left and right to read each line. I just thought it would word wrap. Maybe it's because of the width of the images that were posted. Ron |
| EmfDev |
Posted - 02/21/2020 : 09:46:37
Most people prefer standard reading. |
| rfrazier |
Posted - 02/21/2020 : 08:40:39
PS why are all these lines going off the edge of the screen?
Ron
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| rfrazier |
Posted - 02/21/2020 : 08:39:10
3amado3, Glad to help. Not trying to bury people in jargon but am trying to help them understand this stuff. Always learning new stuff myself as well.
I wanted to clarify something about the distance to measure RF stuff. To measure wifi, or bluetooth, or a microwave oven, which operate at 2.4 GHz, accurately, but given that every meter still reads differently, you have to be 15 INCHES away or more, not feet. (But, if you're going to measure a microwave oven, start on the other side of the room.) To accurately measure a cell phone at .6 GHz (or 600 MHz), you'd have to be 5 FEET away or more. And, just for fun, if you wanted to measure an AM radio station at 600 KHz (1,000 times lower), assuming your meter could even do that, you'd have to be 5,000 FEET away, or 1,000 times further away than the phone.
The problem with wifi in schools, etc. is this. It's not just the router. Every computer, every tablet, every phone (if using wifi), is a transmitter at 2.4 GHz. Phones also transmit to the cell tower multiple times per minute. Usually the router will be at least 6 feet away. But, all those computers, tablets, and phones are inches away, or right on the student's body. This is very bad. My observation with my pro meter, and even the GQ EMF-390, is that any time I'm within 4-6 feet of a wifi device, I'm exceeding the 1000 uW/m^2 that Building Biology people say is extreme exposure. Of course, you're way below the FCC's ridiculous 10,000,000 uW/m^2 limit, which is useless.
Ron
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| 3amado3 |
Posted - 02/20/2020 : 19:50:56
EmfDev, you are correct, it somehow was set to Sensitive, after going back to Standard I saw results similar to before.
But now which is the correct one to use? What is the difference? Standard obviously makes me feel better about my surroundings, but if Sensitive is the more accurate number I'd want to know! I'll skip the factory reset for now unless you feel otherwise then. Should I be upgrading my version though? Thanks!
Ron, yes I actually read your post a few times the last couple days (a lot to take in!) Thank you for the info! Good to know about distances - wifi is mainly what I've been testing (home and at school). The numbers are definitely much lower 15' away - so I guess I just have to take that into account if the students are sitting 10' from a router. |
| rfrazier |
Posted - 02/20/2020 : 16:36:29
Hi 3amado3, I recently posted a long post telling a great deal
about how to use the meter and how the controls work, how to point
it, how units work, and how to take RF readings, what readings mean,
standards, etc. You may find it interesting and I think it will
answer many of your questions.
https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=8856
Be aware of a couple of things. Every meter, every meter, will read
differently. There are a large number of reasons. Use the meter to
get a feel for what's going on. For what it's worth, this meter
usually reads lower than my professional grade meter for RF.
Also be aware that no meter will read RF accurately unless you're in
the "far field". This is discussed in my post. Essentially, if you're
reading something at 2.4 GHz, like wifi or bluetooth, you must be at
least 15" away from the source to get an accurate reading. If you're
reading a cell phone that's transmitting on 600 MHz, for example, you
must be at least 5' away. Putting the meter very close to a source
will not give accurate readings. This is true of all meters.
Finally, you have to know how to point the meter. This is also
discussed in my post. Pointing the meter wrong will also get wrong
readings.
Hope this helps.
Ron
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| EmfDev |
Posted - 02/20/2020 : 15:53:16
Hi 3amado3, I think you need to do a factory reset to your device. It could be that the RF Sensitivity is toggled, you can see it somewhere in the Main Menu->User Options. Toggle RF Sensitivity to "Standard". |
| 3amado3 |
Posted - 02/20/2020 : 14:17:51
Ok, I put my meter away for about 7 or 8 months and just turned it back on a couple nights ago to check some readings of the wi-fi at my kids school. I noticed the battery was down to about 15% so i plugged it into my PC to charge over night. Does this update anything else on the 390?
The reason I ask is because in All-in-one mode, the RF readings seem constantly high. From my posts above (last May), you can see that it was regularly close to 0 mW/m^2 throughout my house (unless I was close to a router/microwave etc). Now it doesn't go much below 20 mW/m^2 ever, and often shoots much higher! The same is the case anyplace else I go (school, home, car, outdoor etc). The lowest I've seen it get is about 12 mW/m^2.
I'm hoping the world hasn't gone RF-crazy on me and I just need to update something, but just wondering if you've seen this before, literally all I did was charge it? It says I'm on version 2.5.
Thanks! |
| EmfDev |
Posted - 05/22/2019 : 09:08:20
In the all in one mode, the range of detection is .24-10GHz but in the spectrum mode it's only 2.4-2.5GHz. Also each channel is only 812kHz bandwidth.
The spectrum lets you see in which frequencies some RF transmitter operates. And how tell you about how strong it transmits the data. the 0.04 is the density of the channel with the triangle. |
| 3amado3 |
Posted - 05/21/2019 : 19:19:22
Thank you for the quick responses! I tried to learn about power density and translate it into numbers I would understand, but that didn't work out :)
Instead lets focus on just one thing - it sounds like Spectrum RF is what I should focus on, so here is my issue. In the pics I will now attach I am standing about 3 feet from my router. The all-in-one view shows about 32 mW/m^2, that number makes sense to me. The Spectrum view shows .045 mW/m^2, that does not make sense to me. Is there some setting I need to adjust or am I just not understanding something?
(sorry - I don't know how to make those pics smaller!)
One thing that just dawned on me, putting it in math terms, does the Spectrum view basically represent the PDF of a distribution (just showing a tiny point in time) and the All-in-one view is like the CDF with it being more grouped up? If so, is there a way to look at the Spectrum view "grouped up" since .04 mW/m^2 doesn't really tell you much when you are reading what levels are safe or comparing to the bulk of the discussions on the topic.
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| EmfDev |
Posted - 05/21/2019 : 13:13:09
1. The upper right is the power density of the peak (from dbm to power density). And the powers are corresponding to the density, same values but different units. The sum is the total power of all the frequency range. The bottom number is the minimum power detected within the range.
In dBm mode, the Chn: in the upper right tells you the channel bandwidth and channel spacing of each channel.
2. sorry the second one 1mW/cm^2 = 1000mW/m^2.
3. Sorry I thought you also cared about cell phone signals. But for just WiFi, the 2.4-2.5GHz spectrum is the best to use. The RF Spectrum 2.4-2.5GHz is for measuring signals like bluetooth, wifi, microwave, etc. You can probably see the graph in the Spectrum jumping too fast and high when you're close to a router that's because WiFi signals are transmitted fast and in a very short period of time. So on the upper right where it says mW/m^2, it should at least go up or down depending on the signal strength.
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| 3amado3 |
Posted - 05/21/2019 : 12:13:03
1. ok i set RF Spectrum to measure in Watts instead of dBm, so at least now it is saying something. But the upper left corner is in pW (sum) and constantly changing (so it's hard to read), but always in the 400 range no matter what I point it at. The upper right is in mW/m^2 and also constantly changing, but seems to always be about about .2 mW/m^2 no matter what I point it at, and the bottom of the screen is also in pW and pretty much always says .3 or .5.
I don't know how to translate pW into any of our other metrics, but the mW/m^2 is nowhere close to the readings i see on the other screens, it is much lower. I also changed the RF sensitivity to Sensitive (I had it on Standard due to a response I saw elsewhere in the forum) - but changing that really didn't do anything for my results.
2. Sorry, i added the link above. Your conversions help. So the link doesn't list mW/m^2, and W/m^2 is different than I thought above as your formulas showed me (although I think your second formula needs adjusting).
3. ok, i had it set to 3 seconds, that makes sense. Although you say here that all in one mode should be best, but in #1 above you said RF spectrum so I'm still confused. If it's RF spectrum then I still have the issue of the numbers not making any sense to me as noted in #1. But knowing that cell phones are more sensitive than the 390 at least tells me why I get a signal in the bedrooms when the 390 says that nothing should be making it there.
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| EmfDev |
Posted - 05/21/2019 : 09:12:15
Hi 3amado3,
1. The WiFi strength gets much weaker with distance. Cellphone WiFi antennas are designed to be more sensitive to WiFi signals than the 390. If you specifically wan't to chech wifi signals, use the 2.4-2.5GHz band in RF spectrum.
2. I don't quite get what you were asking and there's no link.
1000mW/m^2 = 1W/m^2.
1mW/cm^2 = 1000mW/cm^2.
10,000 mW/m^2 = 1 mW/cm^2 = 1000uW/cm^2
3. In RF Browser, the upper left corner is the highest reading within the whole screen. The whole screen covers reading between 1-12 seconds depending on your settings. The upper right corner is the current reading that's why it changes a lot because RF is not constant. AllInOne Mode should be best, you can also try to set the RF Sensitivity under User Settings to Sensitive.
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