[xoa]

For a brief, beautiful moment from the headline I thought "oh good, more PoE sensors finally happening!" doho. But no not just about battery but any power at all, and an interesting approach for further research. Of course to actually get data from still requires powered devices but in a lot of cases it'd be much easier to have that be a single or small number of more easily placed central units vs every single sensor tag separately. Ultra low cost and simplicity are values all their own in terms of applications.

My biggest immediately question though and one I'm a little surprised not see addressed, even at the research stage, is any mention of other animals. There is a bunch there about the ultrasonic frequency being well above the human limit of ~20 kHz. But IIRC for example dogs can hear up to like 45-60 kHz, and cats all the way to 65-85 kHz. I assume lots and lots of other animals also can perceive sounds well beyond human senses. Noise pollution is already a somewhat unrecognized but big problem for all sorts of life around us (not that it's irrelevant to human health either), so if more use of ultrasonics made that worse that's a concern. And as a practical matter the product market is probably going to shrink pretty dramatically if it drives pets mad, a lot of people have pets nowadays they care about a great deal. For that matter even in public environments if it messed with service dogs that might have ADA or equivalent implications.

Still, good reminder of various side channels one doesn't always think about.

[dn3500]

Children too. My own hearing extended to about 23 kHz until I was in my early 20s, and I don't think I was exceptional. There was a jewelry store in my town that I couldn't go in to because the "ultrasonic" motion detector was so painfully loud. But I doubt these devices would be a problem for children or pets because the pulse is so short.

[pavel_lishin]

My hearing is still keen enough that when I'm biking around, I avoid certain streets because those houses have anti-rodent ultrasonic systems that hurt my ears.

[simpleintheory]

Are you sure it wasn’t one of these? https://en.wikipedia.org/wiki/The_Mosquito

[dn3500]

Yes. This was more than 50 years ago. The store owner let me examine the device. It was wired into his alarm system. It even had the frequency listed on the label.

[madaxe_again]

I mean, TV. Kids were definitely a market for it, throughout its history, but until the flat panel era nobody cared that the flyback transformer in most CRTs made a deafening whine in the 20khz range. I could walk into a house and hear a soundless TV three rooms away, and I know I wasn’t alone in that.

[Animats]

Not quite that high. Around 15KHz. (15,734 Hz for NTSC, 15,625 Hz for PAL.)

[invalidSyntax]

Yeah I could too(not know though...). Trying to sleep, and knowing your parents are watching TV in the living room few doors away isn't the best experience.

[drfloyd51]

That’s what that was? I had no idea. I just knew I could hear muted TVs whine. I asked my parents about it. They couldn’t hear it. So I wasn’t sure if it was real.

I feel so relieved.

[Ajoha]

Sorry, humans cannot hear up to 23kHz. Our hearing ends at 20kHz. Point. After a decade on earth your loss is already at 18kHz or less. (Loss means not: you hear nothing but you do not hear as good as when you where born).

[Neywiny]

Incorrect https://en.wikipedia.org/wiki/Hearing_range#Humans

If it's 28 in perfectly ideal conditions, 23 is well within range

[fleventynine]

PoE is lousy for sensors. The switch will cut the power if you draw less than 10mA (480 mW), so regardless of PHY efficiency (which is terrible compared to most RS-485, CAN, or even radio ICs), you are REQUIRED by the spec to generate heat that will mess up your sensor measurements.

[xoa]

>The switch will cut the power if you draw less than 10mA (480 mW), so regardless of PHY efficiency [...] you are REQUIRED by the spec to generate heat that will mess up your sensor measurements.

Out of genuine curiosity, could you elaborate on this further, or share some sources I could read more on? I knew that was once the case, but my understanding was that significant improvements were made for the Maintain Power Signature (MPS) requirements with dual signature and PD standards in the 802.3bt update. According to [0], in the section on 145.3.9 PD MPS:

>"To further reduce minimum standby power consumption for PoE systems, Type 3 and Type 4 dual-signature PDs can make use of optimized MPS timings when connected to a Type 3 or Type 4 PSE, as shown in Figure 19. PDs assigned to Class 1 through 5 must draw a current of 10 mA for at least 7 ms with no more than 310 ms between pulses. This translates to an average power consumption of 12 mW per pairset, or about 1/10th (12 mW/ 124.6 mW ) of the Type 1 / Type 2 minimum pulse average power consumption."

So my assumption was that the spec had significantly improved on this front starting around 7 years ago? I mean, I'm aware that there can be a very, very great deal of lag time between specs and sufficiently cheap and developed new chipsets taking advantage, but I don't think that's the spec's fault either. In principle if the market was there (and yes, it isn't) the tech could meet it right? My extremely limited experience too is that typical wireless battery powered setups can be sensitive to heat as well in the few applications I've dealt with where it's significant, which makes me wonder if in practice in some cases it might be better to use an IR sensor aimed at a semi-closed or closed but air separated material with known (presumably as close to 1.00 as feasible?) thermal emissivity.

Still, there's lots of sensor use cases where it just doesn't matter, but it'd be nice to be able to hard wire+network on the cheap stuff that's very isolated from wireless signal and physically awkward to get at. I'm fully cognizant though that it's a dream unlikely to be realized, just a personal wish there was more PoE IOT stuff (and while we're at it with magical dream lands that it all had open fully local APIs and everyone worked on first class Home Assistant support and...).

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0: https://ethernetalliance.org/wp-content/uploads/2019/08/EA_P...

[fleventynine]

Good luck finding reasonably priced switches and low power PD ICs that support type 3 or type 4 PoE.

Also, supporting those tiny pulses requires large capacitors to hold a charge in between pulses. That plus the required magnetics make PoE sensors way more bulky and expensive to manufacture than old fashioned RS-485 sensors.

[ZaoLahma]

From the article:

> And they don’t travel very far, so only nearby microphones would “hear” the tag. That makes the devices inherently private, Deng said, because other people wouldn’t detect any activity unless they were within a meter or so.

It would seem these things don't really produce loud noises, so probably not adding much to the noise pollution that already exists in our environments. At the same time it seems the statement kind of negates the "point" of this tech, that you don't need an active (energy consuming) device close to the source of the events that you want to detect. So not sure of how to interpret it.

[kaikai]

I’m interested in having an alarm for my door and the door to my workshop, which doesn’t have power. It would be great to have one “listening station” mounted on my home that can detect sounds from both devices. It’s not that I don’t have power available somewhere, it’s that I don’t have power available in EVERY place I’d want to use them, and don’t want to bother with a battery for every sensor.

[tomaskafka]

I think we already established "eff anyone sharing the planet with us that's not us" the moment we made acoustic underwater sonars that make life hell for any whale or dolphin in 100 km range, so this is keeping that approach ...

[Am4TIfIsER0ppos]

If they are anything like the ultrasonic pest devices people can hear them. I can hear those. I can hear the one a neighbor has near a chicken enclosure every time I walk past on the street.

[nick238]

Why would this be any different from dropping a coin or other small metal object? If you're worried about ultrasonic noise pollution, nearly every SMPS operates there, and they're constantly running.

[mmmlinux]

Out of curiosity what do you find missing from the PoE sensor market?

[xoa]

>Out of curiosity what do you find missing from the PoE sensor market?

I'd be unironically delighted if you could point me at some site helping me find what I've been missing like a goof, because it feels more like the question is "what isn't missing from the PoE sensor market?" It's pretty niche isn't it, with what little there is available also being at enormously increased prices? Take something as simple as "is there water where it shouldn't be", isn't there basically just the Aquo Proteus XE at $350 and, I think maybe one other I can't remember? Surely there are some "call us for a quote" industrial gear too but it's not exactly the common case vs z-wave/zigbee/wifi. Same with pretty much whatever else one might name. Like, what if you want a semi-permanent motion sensor (not a camera), are there any PoE options at all? I think I remember reading someone working on an mmWave one to get it work with HA but that's it. And yes 100% you can say that it's "overkill" or the like but looking at DigiKey's PoE controller pricing doesn't seem like it inherently has to be a huge premium, just isn't anything mass produced.

I mean, it is certainly very arguable that the entire IOT market is and always has been sort of a total mess more than not, and that PoE switches weren't the $50/8-port affairs you can get now either until pretty recently. I totally understand why it's not a thing, I want to be clear this is more of an idle wistful "that'd be a nicer world" along with all sorts of other areas of tech. And I know there are PoE splitters so sometimes you can get roughly the same effect if something has ethernet+power separately. Wireless is also certainly sometimes simply the most sensible option. Just would be nice to have more options when it counted is all. I've dealt with enough odd spaces where it's a pain to get any signal in and even if it's only once every few years it still sucks to have to have somebody work their way in there to replace a battery and sometimes things randomly fritz out, makes one long for good ol' hard wire with super easy ways to just power cycle the switch and eliminate lots of complicated stacks of networking. Ah well.

[haddonist]

https://shop.everythingsmart.io/products/everything-presence...

"Everything Presence Pro is our most advanced presence sensor ever, combining long-range static mmWave, tracking mmWave, PIR, PoE, Ethernet/WiFi connectivity, and optional CO₂ sensing (Sold separately) in a single, ultra-capable device"

USD$93.00

---

https://apolloautomation.com/products/r-pro-1?_pos=1&_sid=f8...

Apollo Automation "R PRO-1 PoE dual mmWave Multisensor (LD2450 | additional LD2412 optional)"

- Dual mmWave Compatibility: LD2412 and LD2450 - TR390 for ambient lux and UV sensing - Optional SCD40 for high-accuracy NDIR CO₂ sensing (extra $20)

USD$69.99

---

Also check out https://www.tindie.com/ - it's a site for small companies & individuals to sell tech-related stuff. A quick POE search turned up Radiation Dosimeters, Air quality meters, BLE gateways and more.

[ssl-3]

I like PoE, too -- ethernet in general is something that I think is pretty swell.

But most people are not like us. They're not interested in wires, and many have grown up in a very connected world where there aren't any wires.

Smart home sensors are already a pretty niche market. People who want smart home devices that use ethernet are a small subset of that niche. By the time we drill down to smarthome stuff that is powered with ethernet, we've lost almost everyone's attention.

...

That said, I've made dumber things than this work. A facility I've done work at has a physical access control system that is "wireless". It's not really wireless, of course; it's got a fuckton of wire, but the comms are at least wireless.

They wanted a pushbutton on their dispatch console's touch screen that could unlock the front door. Easy-enough, right? The console provides contact closures on the back end.

But the "wireless" access control system's only useful interface for this was a stupid key fob, like for a car. It uses a CR2032 battery. It was, again, stupid. I hated it, but I used it anyway.

I powered it with 12VDC that was stepped down with a fixed 3-volt linear regulator. I used some rather nice Japanese-made small-signal relays to "push" the buttons on the fob. Those little relays were, in-turn, controlled by the operation of the dispatch console's relays (which were located a couple of hundred hundred cable-feet away).

It took a couple of hours to put it together. They paid the bill. It's been working fine for years.