Can a HackRF One be used to measure safe/unsafe levels of EMF? - Page 1
Forum section: electronics / general

author: wildsquirrel
author_rank: Newbie
timestamp: October 05, 2018, 03:56:58 am
content: I am a total newbie at this, but I'm interested in getting a HackRF One. While I know there are a ton of more complex things I'm sure I'll use it for once I have it, my primary concern and reason I'm considering it right now is much simpler.I'd like to be able to detect and measure whether there is any potentially harmful EMF from any devices. For example to see whether my microwave is leaking radiation, see just how far away I should put a baby monitor from a baby, how far away I may want to put the cell phone on the night stand etc.I know it can capture data in a wide range of frequencies. However after hours of searching, I'm having a tough time figuring out whether it would be useful for measuring the power level or safety of those signals. All info I find on the web generally rates safe levels in milligauss, however I couldn't find any info if the HackRF can measure this. The software generally shows the signal magnitude in DB, so I am unsure if there is any relation.If the HackRF is not the best tool for this, than can anyone recommend a different tool that is still under about $300? I've seen some emf meters on amazon but they seem quite limited and don't even tell what frequency the radiation is on, which is why I'm hoping to use the HackRF to actually detect the specific frequency, visualize it, and have a useful tool for may other purposes.

author: rs20
author_rank: Super Contributor
timestamp: October 05, 2018, 04:18:57 am
content: Please link to one of these pages that gives safe levels in milligauss?

author: xaxaxa
author_rank: Regular Contributor
timestamp: October 05, 2018, 05:05:08 am
content: A simple diode detector and LED will give you a better rf power level reading.PS: I would recommend the limesdr instead if you are looking to get an SDR; it has better linearity, higher dynamic range, and less spurs.

author: Berni
author_rank: Super Contributor
timestamp: October 05, 2018, 05:53:33 am
content: Living things can tolerate a lot of RF power before it becomes directly harmful. So by the time you have those levels around you would most likely see electronic devices in your hand malfunctioning or even frying completely.But i guess you could use a SDR to look at things like this, but at the point where things could start getting potentially harmful the RF front end of it would probably get saturated and produce garbage, but you should not have RF fields that powerful in your house with normal conditions unless you are a ham with big antenna on your house and pushing some serious power into it.

author: MrW0lf
author_rank: Frequent Contributor
timestamp: October 05, 2018, 09:27:40 am
content: Now there are several separate aspects, one is actually measuring magnetic fields, especially low frequency. There is no good solution for that within ordinary testgear. I use this device:https://www.gigahertz-solutions.de/en/rf-and-emf-meters/low-frequency-emf/me-series/397/me3951aThis is very sensitive device and freq range is even somewhat excessive for most common problems. There are much cheaper ones from same company. Most common problem is AC wiring installed by morons which can turn whole apartments into air core solenoids not to mention danger to wild- and other life by direct electrocution in wetrooms. With such device it can be detected tens of meters away. Installation grid level problems can be detected in whole affected geographic area.Second aspect is static charge in the air or objects. This would also require specialized devices to measure properly.Third aspect is most easy one. Measuring RF fields. For that you could of course use SDR. I have RF Explorer, which is handheld SNA. Price for most "building biology" meters is not justified for non professional use for what they offer. But special ultra wideband antennas for them might pose interest.With SDR you would look for some software that supports full spectrum scan, faster the better. Normally you would see only some some "narrow" window (eg 600MHz for RFEx 6G). But there is software called Touchstone which can do full spectrum scan. However, RFEx has huge gap in full spectrum coverage so it not strictly optimal for "building biology" investigation, or building a shielded lab for example.Edit: Forgot, interesting option if to use differential scope probe to look for crap directly on AC lines:Edit2:https://www.rtl-sdr.com/scanning-spectrum-8ghz-per-second-new-hackrf-update/Quote

author: coppercone2
author_rank: Super Contributor
timestamp: October 05, 2018, 11:11:53 am
content: well some fish use frequency shifting radar but they have special cells for this. like 600hzalso sharks

author: wildsquirrel
author_rank: Newbie
timestamp: October 05, 2018, 02:57:17 pm
content: Thanks for the replies. Just to clarify some info, when I mention unsafe levels of EMF, I'm don't mean levels which will instantly be harmful like what Berni mentioned, I'm referring to the levels which can cause damage over the long term. For example there are studies that suggest cell phone radiation can cause cancer after too much long term exposure, or studies which suggest too strong of signals from wireless devices can cause headaches or other health concerns. Some people may argue if this is true or not, but I'd like to be able to measure all devices I reasonably can, visualize the power myself and see how much it drops off at a greater distance, in order to make my own educated choices about the use and placement of these devices to mitigate those potential risks.I looked into the limesdr that was mentioned by xaxaxa, and it seems to have some advantages, but only goes up to 3.8GHz, so I don't think it will meet my needs since I want to measure 5.8Ghz as well.For the question about pages that give safe levels in milligauss. I won't put a direct link, but if you google safe "emf levels" all the first results as well as the little preview window use this same measurement.Thanks for the detailed reply from MrW0lf. You brought up an interesting point about looking for software to do a full spectrum scan. I'll check into that, since it would be good to see the full spectrum at once, although I think i will know the general frequency range of what I am measuring.I'm curious, you mentioned "Most common problem is AC wiring installed by morons which can turn whole apartments into air core solenoids not to mention danger to wild- and other life by direct electrocution in wetrooms.", do you have any good links or search keywords to suggest so I can read more about this phenomenon later?I noticed MrW0lf's equipment also measured in V and Vrms. One of my concerns with the HackRF is whether it can actually detect strength. Every photo I see measures the signal in DB, but I'm not sure if this is relevant to what I am trying to measure, since there might be some sort of gain or offset involved. For example, take a typical consumer microphone on a camera, it records sound which is also expressed in DB, but most have an automatic gain. If recording a near silent environment but then someone talks, their voice will show up as a high DB level and sound very loud. If recording a very loud environment like a factory, it adjusts the gain so the sounds seem quieter, then if something truly loud happened like an explosion, it will register a higher DB, however since the gain was set different in each environment, if you compared the videos side by side, the voice in the first video may show the same DB level as the explosion in the other video. So I don't know if I could assume a higher DB level measured by the HackRF translates to a more dangerous EMF level or not.

author: Berni
author_rank: Super Contributor
timestamp: October 05, 2018, 04:33:42 pm
content: Im not sure how well these SDRs are calibrated. It could be that they are actually showing dBm power (30dBm is 1W). This is easy to check if you have any RF signal generators to give you a known RF level so that you can check if what the SDR is saying agrees. But i would assume you don't have one since in that case you would likely also have a spectrum analyzer and those are designed to do exactly what you want.None the less you can still do comparative measurements since devices that transmit radio waves are regulated by law. For example WiFi is in most places limited to 100mW of transmit power, in America this is tested by a credited laboratory to make sure it conforms to FCC regulations. So as long as you don't try to somehow trick your router it will transmit very close to 100mW since that's as much as they allows them while the manufacturer doesn't want to go below that because it means less range. So you can use wifi routers under full network load as sort of a reference point.Next step up are mobile phones. They don't have a strict rule on the max RF power but they do have some things regarding human exposure so as long as they optimize there antennas to radiate away from you they can crank up the power. This is typically up to 2 or 3W peak, but depends heavily on what the phone is doing and how good of a signal to the tower it has since the closer it is to a tower the less transmit power it will use to save battery power (This is why its good living close to a tower)The only more powerful radio transmitter in a average American home is a microwave. A correctly working one will probably radiate as much as a wifi router, but a damaged microwave could potentially radiate a large amount of RF power.Its not the power that's the most important tho. Radio waves propagate in 3 dimensions and as a result spread out there power really quickly as the distance increases. Yes cell phone towers might have a pretty huge transmit power, but the fact that they are so high up on towers and use directional antennas to focus the power horizontally means there is actually not that much RF exposure even standing next to one.Also keep in mind that in order to make accurate RF field strength measurements you also need a calibrated broadband antenna and its accompanying antenna characteristic plot so you can compensate for its non flatness.

author: MrW0lf
author_rank: Frequent Contributor
timestamp: October 05, 2018, 05:03:21 pm
content: Quote from: wildsquirrel on October 05, 2018, 02:57:17 pmBTW there are some developments in EU. Some random summary:https://www.jrseco.com/council-of-europe-advice-on-health-risks-of-electromagnetic-radiation/?c=392e40eaa002SBM-2015 standard with various limit values for what can be considered sound living space.https://www.baubiologie.de/site/wp-content/uploads/richtwerte-2015-englisch.pdfQuote from: wildsquirrel on October 05, 2018, 02:57:17 pmWell in general they have done grounding wrong so earth leakage currents start to flow. Marry that with multiway switching and you've got a nice air core transformer. I found one when got noticeable continuous shocks from long LAN cable just lying on the floor during installation. Fault root was large leakage current in gas pipe (!) in apartment downstairs. But sometimes there are even large stray currents in ground related to how grid is built, especially near large industry.Also heres interesting lead:https://www.ncbi.nlm.nih.gov/pubmed/23416176Quote from: wildsquirrel on October 05, 2018, 02:57:17 pmdBm (not just dB!)isstrength. But you have to account for area also. Here you just have to do little homework. For example look units on cheap "electrosmog" meter. You should be able to convert all that back and forth to dBm that conventional gear measures.http://www.tes.com.tw/en/product_detail.asp?seq=300Volt per meterand Power density calculatorhttps://www.qsl.net/pa2ohh/jsvpm.htmhttps://www.everythingrf.com/rf-calculators/dbm-to-wattshttp://referencedesigner.com/rfcal/cal_02.phphttp://wera.cen.uni-hamburg.de/DBM.shtml...and so on. Overall is pointless to do exact science here unless offering pro services. For own consumption you'll find very quickly ballpark values for what is going on and how and if fixable. Main thing that matters isrelativestrength related to your space "natural background" which you mostly cannot change. As rule of thumb you keep all the stuff that can be wired wired. Make sure electrical switches switch phase, not neutral. Keep electronics far from sleeping area etc. Distinct between constant and intermittent sources (DECT for example transmits constantly and strong).

author: PointyOintment
author_rank: Frequent Contributor
timestamp: October 06, 2018, 09:29:06 am
content: Quote from: coppercone2 on October 05, 2018, 11:11:53 am[citation needed]I did a Google search for the phrasesome fish use frequency shifting radarand the only result that mentioned anything like radar being usedbyfish (also the first result) wasthis introductory radar article , which says:Quote from: François Le ChevalierIt doesn't mention frequency shifting of any kind.Quote from: wildsquirrel on October 05, 2018, 02:57:17 pmAlso[citation needed]Quote from: wildsquirrelLast I heard about this topic, there were at least as many studies saying it was harmless, IIRC. But that was several years ago. Also, raw number of studies saying something isn't a good basis for belief—I would prefer to read some good review/survey papers that synthesize the results of a bunch of high-quality studies.I'm currently considering radio waves "GRAS" apart from their heating effect (which obeys conservation of energy), but this is not a religious belief.Quote from: wildsquirrelA very astute prediction.Quote from: wildsquirrelYou mean superstitious choices? (In the absence of a scientific consensus on harmfulness, anyway.)Quote from: wildsquirrelSo you don't know what the unit means, just that "everybody uses it for this". Well, I don't think that's even true.Specific absorption rate(which is what legal limits are set on for cell phones) is measured in watts per kilogram, for example. (Also, look at the "Criticism" section of the SAR article.)Also, you seem to be confused about dB:Quote from: wildsquirrelYou need to understand two things about that unit: 1. It's logarithmic, not linear, so a small reduction in dB can be a halving or more of actual amount. 2. It's not a proper unit, but a ratio. In audio work, it's usually the ratio of the measured sound to either the human hearing threshold or the audio gear's distortion threshold. In radio work, it's often used as "dBm", which means the ratio of the measured signal to one milliwatt. That should resolve your confusion about AGC.

author: coppercone2
author_rank: Super Contributor
timestamp: October 06, 2018, 03:20:57 pm
content: http://nelson.beckman.illinois.edu/courses/neuroethol/models/jamming_avoidance/JAR.htmlI personally have a large cyst under the location where I kept my cell phone for years. Doctor said its not worth the operation unless I get psychologically bothered by it, which I am not really at this point in time.I don't know if its from the sitting pressure, repeated impacts (I like to wear basketball shorts and the phone kinds knocks around in there especially if I move fast), the temperature of the phone (conducted, i.e. when it was playing music), or from electromagnetic heating or from some kind of other electromagnetic effect or from chance, but its a big enough cyst that I kind of have an aversion to carrying a phone on me, just incase.But, I typically like being real loose so I will adjust my clothing to remove any pressure points as soon as I get an opportunity to do so (I do not wear any tight clothing at all), and i stay on the well ventilated side, shorts in cold weather and such, so i find the cyst some what suspicious. It's not a tumor though, at one point in time I almost cut it open with a knife but I got adverse psychological reaction from the blood. I also shower frequently.

author: james_s
author_rank: Super Contributor
timestamp: October 06, 2018, 05:50:59 pm
content: So far I've seen absolutely nothing conclusively linking EMF to any kind of health problems. Given the massive explosion in the use of mobile phones, microwave ovens, radar and other RF emitting devices in the last few decades, the last 10 years in particular I would expect an equally massive increase in health problems but we have seen no such increase. Most of the increases in cancer can be explained by a combination of longer average lifespans and improved diagnosis whereas previously a person may have died of "natural causes" or lived with discomfort caused by an unknown illness now they may determine it was a specific form of cancer or other disease that affected them.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 06, 2018, 06:22:53 pm
content: No, a HackRF cannot measure harmful levels of EMF, whether chronic or acute.Harmful levels will more than overload the detector. Consider a thermometer instead.Tim

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 06, 2018, 06:52:32 pm
content: We've had a huge debate here before on harmful levels of EMF (someone thread hunt) and the genaral consensus is that harmful levels RF would be high enough to likely fry low level meters.However, if you are worried about things like a severely leaking microwave oven (which can happan), you can get decent quality meters for that. (microwave leak meters)

author: GeoffreyF
author_rank: Regular Contributor
timestamp: October 06, 2018, 07:37:41 pm
content: There are all sorts of ways to measure safe/unsafe levels of EMF that are cheaper. Levels a tiny fraction of unsafe would ruin the HackRF.The purpose of the HackRF is to emulate receiver/transmitters across a wide spectrum.I am wondering what you think is "safe/unsafe" with regard to strength and frequency. Folks could advise you better if you were more specific. If you don't know, give us an example of something that might be unsafe in your mind and about which you wish to investigate. Keep in mind the "inverse square law". You don't have to be very far from something that is unsafe, even lethal, to be safe.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 06, 2018, 09:45:31 pm
content: Quote from: GeoffreyF on October 06, 2018, 07:37:41 pmThis is particularly true of well-known hazardous EMF, i.e. UV, x-rays and gamma rays. Well, not always UV, just because it bounces off shiny surfaces and is sometimes broadly illuminated -- e.g. sunlight. But the rest are absorbed by pretty much everything else, and go inverse-square (or better, where shielding material is involved) with distance. The consequences in nuclear accidents bear this out (with gruesome results for those most affected).Tim

author: 4hJXHsxFH
author_rank: Newbie
timestamp: February 13, 2021, 09:54:10 pm
content: this is what i call a super helpful comment.my two cents: i have the rf explorer and i think is a piece of garbage. the best instrument i've found for rf measurement is the acoustimeter or its "junior" version which is the acousticom which is the one i have.I also have the hackrf one, although have not found a great software to get most of it. I've used sdr sharp.any recommendations?

author: 4hJXHsxFH
author_rank: Newbie
timestamp: February 13, 2021, 09:56:11 pm
content: this is what i call a super helpful comment.my two cents: i have the rf explorer and i think is a piece of garbage. the best instrument i've found for rf measurement is the acoustimeter or its "junior" version which is the acousticom which is the one i have.I also have the hackrf one, although have not found a great software to get most of it. I've used sdr sharp.any recommendations?Quote from: T3sl4co1l on October 06, 2018, 06:22:53 pm

author: 4hJXHsxFH
author_rank: Newbie
timestamp: February 13, 2021, 10:05:26 pm
content: milligauss is used for low frequency electromagnetic radiation, like the one caused by home wiring, electric motor, ac systems, and electricity in general. I believe this is frequencies (ultra low emfs) go something like 40 hz to 100,000 hz (100 khz)... pleasr correct my if i'm wrong.on the other hand, rf radiation is the one cause by cellphones, wifi, cellphone towers etc. and the most common are from 2,400,000,000 hz (2.4 gz), 5,000,000,000 hz (5 ghz) and something around there.note that the standard channels for cellphone carriers are like 1800 mhz, 1900 mhz etc. which is in the same rd spectrum.to measure this, the best simple tool to buy is the acousticom (only measures rd) or the tf2, which measures the 3 (magnetic, electric and rf) but my gut (only anecdotal evidence), tells me that for RF the acousticom is beter.even though if you want an overall good general purpose cheap meter, i would go to the trifield tf2 (around 200$)

author: tom66
author_rank: Super Contributor
timestamp: February 14, 2021, 10:39:06 am
content: Any product that calls itself an 'electrosmog' detector needs to be laughed out of the room.

author: jonpaul
author_rank: Super Contributor
timestamp: February 14, 2021, 12:22:19 pm
content: Hello:Kindly suggest that you research and learn the technology before you buy anything.SDR: Hack One reviews, vs the Leo Bodnar SDR Playhttps://www.sdrplay.comAntennas and sensor: The spectrum analyzer or SDR is just a reciever and the transducer r antenna affects the sensitivity, bandwidth, directionality.EMC probes and EMC antennas are a huge topic. The analyzer or SDR without the selected antenna is useless."safe/unsafe levels of EMF"Huge topic, and somewhat controversial and politically affected.The field intensity and bands are in FCC, WHO, CE regulations, for every radio band.Are you interested in WiFi, GSM, 5G, 4G 3G mobile, microwave ovens, high voltage transmission lines?Each needs a different analyzer and antenna! Each has different intensity specs.In short this is a huge field even for the government regulators and equipment manufacturers.Dont expect reliable data from a cheap Chinese spectrum analyzer or SRD, without calibration and a calibrated antenna.Bon Chance,Jon

author: Frequint
author_rank: Newbie
timestamp: March 15, 2022, 06:17:28 pm
content: Hi, I know of these guidelines, perhaps not up-to-date but they give a good indication I think.https://europaem.eu/attachments/article/124/EUROPAEM_EMF_Guideline_2016_English_Original.pdfPg 17 & 18.Hope its help full

author: TimFox
author_rank: Super Contributor
timestamp: March 15, 2022, 08:30:52 pm
content: Note that there are two quite different parameters:When you hold the phone up to your head, you are in the "near field" region, where there is no radiation, but energy is stored in the local field. The effect of this is measured in "SAR", which is the rate at which you absorb energy from the oscillating RF field. Regulations give maximum allowable safe levels of this parameter, but muckraking articles in responsible media have found that some phones (measured in a qualified testing lab) did exceed the legal limit.When you are many wavelengths away from a cellular tower or high-power broadcast station, you are now in the "radiation field" region, and the RF power is radiating past you. This falls off as inverse-square of the distance.With 60 Hz AC, the wavelength at the low frequency is extremely long, and you will always be in the "near field" region, as in the example above of a mis-wired room where the wiring forms a loop around you. (I encountered such a loop once when my in-laws asked me to fix a light switch in an old house.)

author: El Rubio
author_rank: Regular Contributor
timestamp: March 16, 2022, 04:37:47 pm
content: Quote from: TimFox on March 15, 2022, 08:30:52 pmMaybe you mistyped, but there is absolutely RF radiation in the near field of a transmitting antenna. Also, farther away, the RF power is not necessarily radiating "past you". If you, or part of you, is resonant, that part will absorb the RF it is exposed to. I don't mean to critique your post, but I'm also confused by your description of the 60Hz loop from household electrical wiring. Can you explain that and what you experienced?

author: TimFox
author_rank: Super Contributor
timestamp: March 16, 2022, 05:04:43 pm
content: In the near field of a transmitting antenna, the predominant effect is the energy "stored" in the oscillating (not radiating) field. "Past you" was just a description of the direction. A conductive object (like the saline in the human body) will absorb energy from either of these fields. If the dimensions of the object are a resonant condition at that frequency, the absorption will be enhanced.The wiring error I mentioned was using two SPDT ("three-way") switches to control a ceiling light, where a wire went from the common contact of one switch to the ceiling fixture and then to the common contact of the other switch. At each end, the fixed contacts were connected to line and neutral. This formed a loop, but I was not worried about the AC field. The real problem was that the switches tended to "make" just before "break", giving a temporary short between line and neutral, eroding the switch contacts.