I can't scan documents when my daughter is asleep. When she is awake, all is fine, but the minute she goes to sleep, and I'd like to use my free time to scan documents and suchlikes, forget it. I could still print documents on the same device though. Here's what I found:
The printer-scanner was connected to wi-fi. The wi-fi router was in my daughter's room, as that is where the cable socket was, tucked just behind a bench in her room. It was also near that bench that her baby monitor camera was standing. It wasn't wi-fi connected, but for whatever reason it interfered with the wi-fi signal. Same with the receiver, if I put it near my laptop, the wi-fi connection would die.
The monitor was off most of the time, and on precisely when my daughter was asleep.
As for why I could still print, just not scan: presumably that's something to do with the bandwidth, I'm guessing it took more wi-fi bandwidth to send a scanned image than to print a document (I never printed pictures on this printer).
Yeah, baby monitors are THE worst behaving radio devices. They would be second after malfunctioning neon sign transformers, but transformers are not intended as radio devices.
As for why scanner and not printer losing connection - probably printer has small buffer and scanner doesn't pause when that send buffer is full due to trying retransmissions, but stops completely. Printer probably can wait for more data.
Still... my thinking is, I'd rather a crappy baby monitor than a badly-secured device connected to wifi, and by extension, the whole world.
We do actually have a spare camera we sometimes take away, that works on Wi-Fi. I accidentally left it once at my parent's place, then travelled back home overseas. I got a notification of my baby crying desolately as I got off the plane. Turns out it was my family arguing something in the room where my daughter was staying, and the camera somehow switched itself back on. It was freaky!
The main reason 2.4GHz band is unlicensed (anyone can broadcast on it without e.g. a ham license) is because it's garbage. Baby monitors and microwave ovens are two of the most common offenders for dumping large amounts of noise into that band. If you can move the printer to a 5GHz band, that could help a lot.
And in the near future, wifi 6E will add a ton of spectrum, allowing devices to just avoid noisy channels. But to use that you'll have to upgrade the printer or add a wifi 6E bridge.
Had a Customer who complained that the Wi-Fi in one of their conference rooms was "always" unreliable. I checked it multiple times and didn't find any problems-- low SNR, strong signal, low airtime utilization.
Eventually I learned out that "always" meant a particular recurring lunchtime meeting, scheduled right when a steady stream of workers were going into the break room across the hall and heating food in a microwave oven.
I had a Panasonic 2.4Ghz jamming device. Could take out channels 1-11 all at the same time. It wasn't supposed to be a jamming device, it was supposed to be a cordless phone. Setup wifi for a customer, and it worked fine when I was on site. Later the customer complained it was completely unusable, in what they thought was a random fashion.
Turned out whenever they used the cordless it pretty much made so much noise on the 2.4G frequence wifi wouldn't work. Phone itself worked fine. Had them get new phones and the problem went away.
Reminds me of a story from my colleague, who used to work at a tech help desk at a telecom some years ago. He told me about a curious case of a house which, despite being located next to the network node, appeared as if it was kilometers away from the signal loss POV. It turned out that for unknown reasons, instead of cutting the necessary length of cable to install, someone just connected both ends through a fresh cable spool and buried that spool underground.
You really want to think about moving the Wi-fi out of the baby's room. Get a GQ-390 meter and you will see the torrent of dangerous radiation flooding her room, above recommended levels.
I was able to get my Internet provider to relocate the device to my basement.
I used to work for an IPTV provider (who also happens to make a search engine). We received TV feeds from TV stations via satellite; we had an antenna farm, received their signals there, compressed/encoded the signal, and then sent them to customers over the network. Because we only had one antenna farm, we would have TV outages throughout the year -- sometimes the satellite happens to be directly in front of the sun, and the sun is a huge RF emitter that would overwhelm our receivers. (I asked if we can just move the satellites, but was told that we didn't have the delta-V budget. We eventually built another antenna farm. Another question I asked is why can't the TV stations just send us video files over the network. Apparently it simply isn't done; they have used satellites for decades, so why switch?)
My comment is an unresearched, not even cursorially google-searched, from-memory assertion, so take with 5 buckets of salt please, and if I'm wrong I'd like to correct my ignorance, so someone please correct me :)
My understanding is that Wi-Fi, cellular (no matter the 12345G) and radio signals are all harmless in 99.99999% circumstances as they are non-ionizing radiation. They are no more harmful to you than light photons.
In fact, Wi-Fi signals might be safer than light. Since you don't have eyes sensitive to the EM wavelength of Wi-Fi, you can't shine a 'wifi light' too brightly next to you.
Damaging radiation as we think of it is most often in the form of ionizing radiation such as too much sunlight, microwaves that excite water molecules, or high amounts of alpha / beta / gamma particles that can mess with DNA etc. and thus cause cancer as DNA damage accumulates.
> Since you don't have eyes sensitive to the EM wavelength of Wi-Fi, you can't shine a 'wifi light' too brightly next to you.
This is dangerously wrong. Vision damage is not prevented by the wavelength not being in the visible spectrum. Even if you can't see it, and even if it is non-ionizing, electromagnetic waves still impart energy.
Eyes cannot efficiently dissipate heat, so sufficiently strong EMF will damage the eye. This is a well-known risk when operating with strong microwave signals, for example.
"Effects of Microwave and Millimeter Wave Radiation on the Eye", J. A. D’AndreaS. Chalfin, NATO Science Series book series (ASHT, volume 82)
> Most of the early research was carried out in the lower portion of the microwave spectrum (at 2.45 GHz) and demonstrated a high dose response relationship between microwave exposure and cataract induction. For example, Carpenter and Van Ummersen irradiated anesthetized rabbits at 2.45 GHz and showed a decreasing threshold for cataractogenesis from 4 minute exposure at 400 mW/cm2 to 40 minutes at 80 mW/cm2• Guy et al. ... repeated some of the earlier research and found essentially the same threshold for cataract production in rabbits exposed with a near field applicator at 2.45 GHz. At minimum, they determined that 150 mW/cm2 was required for 100 min to produce a cataract.
Not saying your Wi-Fi router is going to cause cataracts, but don't think just because you can't see something it can't hurt your vision. In fact, it could be argued invisibly strong EMF is _more_ dangerous than visible light because it doesn't trigger the self-protective blink reflex.
So? EM induces other kind of cellular changes. Maybe not as immediately disruptive as ionizing radiation. Just look up the study linking neuroglioblastoma incidence correlates to the side of the head one uses their cellphone.
> Just look up the study linking neuroglioblastoma incidence correlates to the side of the head one uses their cellphone.
Yes, do. Then read the rest of it. Some choice comments from cancer.gov[0]:
> Most published analyses from this study have shown no statistically significant increases in brain or other central nervous system cancers related to higher amounts of cell phone use. One analysis showed a statistically significant, although modest, increase in the risk of glioma among the small proportion of study participants who spent the most total time on cell phone calls.
> However, the researchers considered this finding inconclusive because they felt that the amount of use reported by some respondents was unlikely and because the participants who reported lower levels of use appeared to have a slightly reduced risk of brain cancer compared with people who did not use cell phones regularly.
Oh look, actually cell phones prevent cancer. Totally. Because one-off results are reliable like that.
It's okay, most experts thought the earth was flat at some point. If you want to learn more about goverments' approach to many health issues I encourage you to read on the history of the concept of hormesis. While the first studies show ionizing radiation to be harmful at any level, of course they later founded researchers who came up with this theory so plenty of lawsuits could be avoided. I already live most aspects of my life as a top 1%, so if there is any risk that EMF can have harmful consequences and it is within my control, I'll mitigate it. 99% percent of the population don't care, don't believe, it's okay. Primary housing in a secluded area? Check. Wired Networking? Check. Non industrialized nutrition on point? Check.
Think there is no theory behind the impact of EMF on living organisms? Might want to read on how cells maintain ions in balance, through passive and active diffusion through the membrane. Easily altered with EMF, can our cells adapt? Sure. Could this adaptation bring other issues/degeneration? Sure
The printer-scanner was connected to wi-fi. The wi-fi router was in my daughter's room, as that is where the cable socket was, tucked just behind a bench in her room. It was also near that bench that her baby monitor camera was standing. It wasn't wi-fi connected, but for whatever reason it interfered with the wi-fi signal. Same with the receiver, if I put it near my laptop, the wi-fi connection would die.
The monitor was off most of the time, and on precisely when my daughter was asleep.
As for why I could still print, just not scan: presumably that's something to do with the bandwidth, I'm guessing it took more wi-fi bandwidth to send a scanned image than to print a document (I never printed pictures on this printer).